Arterial Blood Gas (ABG) Interpretation Practice Exam

Arterial Blood Gas (ABG) Interpretation Practice Exam

 

Which of the following represents normal arterial blood gas (ABG) values?

pH 7.25, PaCO₂ 55 mmHg, HCO₃⁻ 30 mEq/L
B. pH 7.45, PaCO₂ 35 mmHg, HCO₃⁻ 22 mEq/L
C. pH 7.35, PaCO₂ 45 mmHg, HCO₃⁻ 28 mEq/L
D. pH 7.50, PaCO₂ 20 mmHg, HCO₃⁻ 15 mEq/L

 

A pH of 7.30, PaCO₂ of 50 mmHg, and HCO₃⁻ of 24 mEq/L indicates:

Metabolic acidosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis

 

The term “compensated respiratory acidosis” means:

pH < 7.35, PaCO₂ ↑, HCO₃⁻ ↑
B. pH normal, PaCO₂ ↑, HCO₃⁻ ↑
C. pH > 7.45, PaCO₂ ↑, HCO₃⁻ ↓
D. pH normal, PaCO₂ ↓, HCO₃⁻ ↓

 

Which of the following can cause metabolic acidosis?

Vomiting
B. Hypoventilation
C. Diarrhea
D. Hyperventilation

 

What compensatory mechanism occurs in metabolic alkalosis?

Hyperventilation
B. Hypoventilation
C. Increased bicarbonate excretion
D. Increased bicarbonate reabsorption

 

A patient has pH 7.50, PaCO₂ 30 mmHg, and HCO₃⁻ 24 mEq/L. This is indicative of:

Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Metabolic alkalosis

 

The anion gap is useful in diagnosing:

Respiratory alkalosis
B. Non-anion gap metabolic acidosis
C. High-anion gap metabolic acidosis
D. Compensated respiratory acidosis

 

A pH of 7.20, PaCO₂ 60 mmHg, and HCO₃⁻ 28 mEq/L indicates:

Uncompensated metabolic acidosis
B. Partially compensated respiratory acidosis
C. Fully compensated respiratory acidosis
D. Mixed acidosis

 

Which ABG abnormality is commonly seen in sepsis?

Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis

 

A patient with an opioid overdose is likely to present with:

Metabolic alkalosis
B. Respiratory alkalosis
C. Respiratory acidosis
D. Metabolic acidosis

 

PaO₂ levels below 60 mmHg are classified as:

Hypercapnia
B. Hypoxia
C. Hypoxemia
D. Hyperventilation

 

Which of the following represents uncompensated metabolic acidosis?

pH 7.25, PaCO₂ 35 mmHg, HCO₃⁻ 18 mEq/L
B. pH 7.36, PaCO₂ 40 mmHg, HCO₃⁻ 24 mEq/L
C. pH 7.45, PaCO₂ 25 mmHg, HCO₃⁻ 18 mEq/L
D. pH 7.30, PaCO₂ 50 mmHg, HCO₃⁻ 26 mEq/L

 

Respiratory alkalosis is commonly caused by:

Hypoventilation
B. Diabetic ketoacidosis
C. Hyperventilation
D. Kidney failure

 

A patient with chronic obstructive pulmonary disease (COPD) is most likely to have:

Respiratory alkalosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Metabolic acidosis

 

If PaCO₂ increases, what happens to the pH?

It increases
B. It decreases
C. It remains unchanged
D. It fluctuates

 

A patient with pH 7.38, PaCO₂ 48 mmHg, and HCO₃⁻ 29 mEq/L has:

Fully compensated metabolic alkalosis
B. Fully compensated respiratory acidosis
C. Mixed acidosis
D. Normal ABG

 

Hyperventilation during a panic attack results in:

Respiratory acidosis
B. Metabolic acidosis
C. Respiratory alkalosis
D. Metabolic alkalosis

 

Which electrolyte imbalance often accompanies metabolic alkalosis?

Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hyponatremia

 

An ABG shows pH 7.55, PaCO₂ 25 mmHg, HCO₃⁻ 24 mEq/L. The interpretation is:

Metabolic alkalosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Respiratory acidosis

 

What is the primary buffer system in the body?

Phosphate buffer system
B. Bicarbonate buffer system
C. Protein buffer system
D. Hemoglobin buffer system

 

Hypoxemia is defined as:

PaO₂ < 80 mmHg
B. PaO₂ < 60 mmHg
C. PaO₂ > 100 mmHg
D. PaO₂ < 50 mmHg

 

Diabetic ketoacidosis typically results in:

Metabolic acidosis with high anion gap
B. Metabolic alkalosis with normal anion gap
C. Respiratory acidosis
D. Respiratory alkalosis

 

Which ABG finding is most consistent with acute asthma exacerbation?

Respiratory alkalosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Mixed alkalosis

 

Prolonged vomiting results in:

Metabolic acidosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis

 

Which compensatory mechanism is expected in respiratory acidosis?

Increased bicarbonate retention
B. Increased CO₂ excretion
C. Decreased bicarbonate reabsorption
D. Increased hydrogen ion excretion

 

The kidneys regulate pH by:

Adjusting PaO₂ levels
B. Adjusting PaCO₂ levels
C. Retaining or excreting bicarbonate
D. Retaining or excreting CO₂

 

A pH of 7.28, PaCO₂ of 55 mmHg, and HCO₃⁻ of 26 mEq/L suggests:

Respiratory acidosis
B. Metabolic acidosis
C. Mixed acidosis
D. Compensated respiratory acidosis

 

In which condition is PaCO₂ likely to decrease?

Hypoventilation
B. Pneumonia
C. Hyperventilation
D. COPD

 

Mixed metabolic acidosis and respiratory alkalosis may occur in:

Sepsis
B. Chronic renal failure
C. Diabetic ketoacidosis
D. Pulmonary embolism

 

What is the normal range for HCO₃⁻ in ABG analysis?

20-25 mEq/L
B. 22-28 mEq/L
C. 24-30 mEq/L
D. 25-35 mEq/L

 

 

Which of the following conditions can cause respiratory alkalosis?

Anxiety or panic attack
B. Chronic obstructive pulmonary disease (COPD)
C. Hypoventilation from opioid overdose
D. Renal failure

 

What is the primary abnormality in metabolic alkalosis?

Excess CO₂ retention
B. Decreased bicarbonate concentration
C. Increased bicarbonate concentration
D. Increased hydrogen ion concentration

 

A patient with pH 7.50, PaCO₂ 50 mmHg, and HCO₃⁻ 34 mEq/L has:

Metabolic alkalosis with partial respiratory compensation
B. Respiratory alkalosis with metabolic compensation
C. Metabolic acidosis with respiratory compensation
D. Respiratory acidosis

 

What compensatory mechanism is activated in metabolic acidosis?

Hypoventilation to retain CO₂
B. Hyperventilation to excrete CO₂
C. Renal excretion of bicarbonate
D. Renal retention of CO₂

 

A normal anion gap metabolic acidosis is most commonly caused by:

Diarrhea
B. Diabetic ketoacidosis
C. Lactic acidosis
D. Salicylate poisoning

 

Which of the following ABG results indicates respiratory failure?

PaO₂ 75 mmHg and PaCO₂ 40 mmHg
B. PaO₂ 85 mmHg and PaCO₂ 30 mmHg
C. PaO₂ 50 mmHg and PaCO₂ 60 mmHg
D. PaO₂ 92 mmHg and PaCO₂ 38 mmHg

 

A patient with asthma exacerbation has pH 7.32, PaCO₂ 60 mmHg, and HCO₃⁻ 26 mEq/L. This indicates:

Respiratory alkalosis
B. Respiratory acidosis
C. Metabolic acidosis
D. Mixed respiratory and metabolic acidosis

 

What is the hallmark of fully compensated metabolic acidosis?

Normal pH with low HCO₃⁻ and low PaCO₂
B. Low pH with low HCO₃⁻ and normal PaCO₂
C. High pH with low HCO₃⁻ and low PaCO₂
D. Normal pH with normal HCO₃⁻ and normal PaCO₂

 

A pH of 7.48, PaCO₂ 30 mmHg, and HCO₃⁻ 18 mEq/L suggests:

Uncompensated respiratory alkalosis
B. Partially compensated respiratory alkalosis
C. Fully compensated respiratory alkalosis
D. Mixed alkalosis

 

Which of the following causes metabolic alkalosis?

Ketoacidosis
B. Loop diuretic use
C. Lactic acidosis
D. Diarrhea

 

What ABG value determines the adequacy of ventilation?

pH
B. PaO₂
C. HCO₃⁻
D. PaCO₂

 

A pH of 7.52, PaCO₂ 45 mmHg, and HCO₃⁻ 36 mEq/L indicates:

Metabolic alkalosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Respiratory acidosis

 

A pH of 7.18, PaCO₂ 38 mmHg, and HCO₃⁻ 15 mEq/L suggests:

Metabolic acidosis without compensation
B. Metabolic alkalosis with compensation
C. Metabolic acidosis with compensation
D. Respiratory acidosis

 

A patient with severe diarrhea is likely to have:

Respiratory alkalosis
B. Metabolic acidosis
C. Metabolic alkalosis
D. Respiratory acidosis

 

Which of the following ABG patterns is consistent with lactic acidosis?

Low pH, low HCO₃⁻, and normal anion gap
B. Low pH, low HCO₃⁻, and high anion gap
C. High pH, high HCO₃⁻, and low anion gap
D. Normal pH, high HCO₃⁻, and low PaCO₂

 

In which situation would a patient experience mixed respiratory and metabolic acidosis?

Diabetic ketoacidosis with sepsis
B. Acute hyperventilation during anxiety
C. COPD exacerbation with vomiting
D. Acute renal failure with hyperventilation

 

A low PaO₂ with normal PaCO₂ and normal pH is indicative of:

Respiratory acidosis
B. Hypoxemia without ventilatory failure
C. Compensated respiratory acidosis
D. Mixed acidosis

 

Which ABG finding is most consistent with a pulmonary embolism?

Respiratory alkalosis
B. Respiratory acidosis
C. Metabolic acidosis
D. Mixed alkalosis

 

A patient with renal failure is likely to have which ABG abnormality?

Metabolic alkalosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Mixed alkalosis

 

What is the expected PaO₂ for a healthy individual breathing room air at sea level?

50-60 mmHg
B. 70-80 mmHg
C. 80-100 mmHg
D. 100-120 mmHg

 

 

Which of the following is true about PaCO₂ in respiratory acidosis?

It is low, indicating hyperventilation.
B. It is elevated, indicating hypoventilation.
C. It remains within normal range.
D. It compensates by increasing bicarbonate levels.

 

A pH of 7.22, PaCO₂ 28 mmHg, and HCO₃⁻ 12 mEq/L suggests:

Respiratory alkalosis
B. Metabolic acidosis with partial respiratory compensation
C. Mixed metabolic and respiratory acidosis
D. Fully compensated metabolic acidosis

 

In chronic respiratory acidosis, the kidneys compensate by:

Excreting more bicarbonate
B. Retaining hydrogen ions
C. Retaining bicarbonate
D. Increasing PaCO₂ levels

 

What is the best way to distinguish between acute and chronic respiratory acidosis?

Measure the pH alone
B. Check the PaO₂ level
C. Assess the bicarbonate concentration
D. Use the anion gap calculation

 

A patient with diabetic ketoacidosis is likely to have:

Respiratory alkalosis
B. Metabolic alkalosis
C. High anion gap metabolic acidosis
D. Normal anion gap metabolic acidosis

 

What is the normal range for arterial bicarbonate (HCO₃⁻) levels?

10-20 mEq/L
B. 22-26 mEq/L
C. 28-32 mEq/L
D. 15-18 mEq/L

 

A patient presents with pH 7.56, PaCO₂ 22 mmHg, and HCO₃⁻ 20 mEq/L. What is the likely diagnosis?

Compensated metabolic alkalosis
B. Partially compensated respiratory alkalosis
C. Fully compensated metabolic acidosis
D. Mixed alkalosis

 

Which of the following is a primary cause of metabolic acidosis?

Prolonged vomiting
B. Excessive diarrhea
C. Panic attack
D. Pulmonary embolism

 

A patient with pH 7.28, PaCO₂ 50 mmHg, and HCO₃⁻ 24 mEq/L is diagnosed with:

Respiratory alkalosis
B. Respiratory acidosis without compensation
C. Respiratory acidosis with metabolic compensation
D. Metabolic acidosis

 

What value indicates the effectiveness of oxygenation?

PaCO₂
B. HCO₃⁻
C. PaO₂
D. Base excess

 

A patient with pH 7.60, PaCO₂ 40 mmHg, and HCO₃⁻ 36 mEq/L has:

Compensated metabolic alkalosis
B. Uncompensated metabolic alkalosis
C. Respiratory alkalosis with metabolic compensation
D. Mixed acidosis

 

What is the most likely ABG abnormality in a patient with an opioid overdose?

Respiratory alkalosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Metabolic acidosis

 

Which of the following causes a high anion gap metabolic acidosis?

Renal tubular acidosis
B. Lactic acidosis
C. Diarrhea
D. Hyperchloremia

 

A PaO₂ of 55 mmHg indicates:

Normal oxygenation
B. Mild hypoxemia
C. Moderate hypoxemia
D. Severe hypoxemia

 

A pH of 7.38, PaCO₂ 48 mmHg, and HCO₃⁻ 30 mEq/L suggests:

Fully compensated metabolic acidosis
B. Fully compensated respiratory acidosis
C. Mixed acidosis
D. Partially compensated metabolic alkalosis

 

Which electrolyte imbalance commonly accompanies metabolic alkalosis?

Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hyponatremia

 

A mixed metabolic and respiratory acidosis could result from:

Severe sepsis with respiratory failure
B. Vomiting and hypoventilation
C. Diarrhea and hyperventilation
D. Panic attack with ketoacidosis

 

How does the body initially compensate for metabolic alkalosis?

By increasing bicarbonate excretion through the kidneys
B. By hyperventilating to lower CO₂ levels
C. By hypoventilating to retain CO₂
D. By increasing hydrogen ion excretion

 

In which scenario is the PaO₂/FiO₂ ratio used?

To assess metabolic acidosis
B. To evaluate hypoxemia in ARDS
C. To diagnose respiratory alkalosis
D. To measure acid-base compensation

 

A patient with a history of chronic renal failure is most likely to have which ABG abnormality?

High anion gap metabolic acidosis
B. Normal anion gap metabolic acidosis
C. Metabolic alkalosis
D. Respiratory acidosis

 

 

Which condition commonly causes respiratory alkalosis?

Chronic obstructive pulmonary disease (COPD)
B. Diabetic ketoacidosis
C. Hyperventilation syndrome
D. Hypoventilation due to neuromuscular disease

 

A patient has a pH of 7.25, PaCO₂ 30 mmHg, and HCO₃⁻ 16 mEq/L. This indicates:

Respiratory acidosis
B. Metabolic acidosis with respiratory compensation
C. Mixed acidosis
D. Respiratory alkalosis

 

Which of the following represents a normal PaCO₂ range?

20-25 mmHg
B. 30-35 mmHg
C. 35-45 mmHg
D. 50-60 mmHg

 

What is the primary disturbance in metabolic alkalosis?

Decreased HCO₃⁻
B. Increased HCO₃⁻
C. Decreased PaCO₂
D. Increased PaCO₂

 

Which parameter is used to calculate the anion gap?

Na⁺ – (Cl⁻ + HCO₃⁻)
B. (Na⁺ + K⁺) – (Cl⁻ + HCO₃⁻)
C. (HCO₃⁻ – PaCO₂) + Cl⁻
D. (Na⁺ + HCO₃⁻) – Cl⁻

 

In chronic respiratory alkalosis, the kidneys compensate by:

Excreting bicarbonate
B. Retaining hydrogen ions
C. Retaining bicarbonate
D. Increasing the respiratory rate

 

A pH of 7.50, PaCO₂ 20 mmHg, and HCO₃⁻ 24 mEq/L indicates:

Uncompensated respiratory alkalosis
B. Uncompensated metabolic alkalosis
C. Compensated respiratory acidosis
D. Fully compensated respiratory alkalosis

 

A patient with sepsis develops lactic acidosis. Which ABG abnormality is expected?

Metabolic alkalosis
B. Normal anion gap metabolic acidosis
C. High anion gap metabolic acidosis
D. Respiratory alkalosis

 

A patient presents with pH 7.32, PaCO₂ 55 mmHg, and HCO₃⁻ 25 mEq/L. What is the primary problem?

Metabolic acidosis
B. Respiratory alkalosis
C. Respiratory acidosis
D. Compensated metabolic alkalosis

 

Which of the following is a hallmark of respiratory acidosis?

Increased pH with decreased PaCO₂
B. Decreased pH with increased PaCO₂
C. Decreased pH with decreased HCO₃⁻
D. Normal pH with increased PaCO₂

 

A 60-year-old smoker with chronic bronchitis is likely to present with:

Acute respiratory acidosis
B. Chronic respiratory acidosis with compensation
C. Uncompensated metabolic acidosis
D. Fully compensated respiratory alkalosis

 

What is the normal value for base excess/deficit in ABG interpretation?

+5 to +10 mEq/L
B. -2 to +2 mEq/L
C. -10 to 0 mEq/L
D. +10 to +15 mEq/L

 

A patient with prolonged vomiting and a pH of 7.52, PaCO₂ 46 mmHg, and HCO₃⁻ 32 mEq/L has:

Metabolic alkalosis with partial compensation
B. Respiratory alkalosis with partial compensation
C. Fully compensated metabolic alkalosis
D. Mixed alkalosis

 

Which condition can cause respiratory alkalosis?

Renal failure
B. Hyperventilation due to anxiety
C. Acute asthma exacerbation
D. Prolonged diarrhea

 

A PaCO₂ of 48 mmHg and pH of 7.38 suggest:

Compensated metabolic acidosis
B. Compensated respiratory acidosis
C. Acute respiratory acidosis
D. Metabolic alkalosis

 

A mixed metabolic alkalosis and respiratory acidosis is most likely caused by:

Severe vomiting with hypoventilation
B. Diarrhea and hyperventilation
C. Renal failure with panic attack
D. Aspirin overdose

 

What is the normal PaO₂ in arterial blood for a healthy individual at sea level?

50-70 mmHg
B. 75-100 mmHg
C. 100-125 mmHg
D. 130-150 mmHg

 

A 25-year-old patient presents with pH 7.45, PaCO₂ 50 mmHg, and HCO₃⁻ 35 mEq/L. This indicates:

Compensated respiratory alkalosis
B. Compensated metabolic alkalosis
C. Mixed acidosis
D. Fully compensated metabolic acidosis

 

Which ABG result is consistent with aspirin overdose?

pH 7.25, PaCO₂ 28 mmHg, HCO₃⁻ 15 mEq/L
B. pH 7.50, PaCO₂ 45 mmHg, HCO₃⁻ 30 mEq/L
C. pH 7.35, PaCO₂ 55 mmHg, HCO₃⁻ 24 mEq/L
D. pH 7.60, PaCO₂ 30 mmHg, HCO₃⁻ 24 mEq/L

 

A patient with ARDS (Acute Respiratory Distress Syndrome) is likely to have:

Respiratory acidosis with severe hypoxemia
B. Metabolic alkalosis with hyperoxemia
C. High anion gap metabolic acidosis
D. Normal ABG values

 

 

A 70-year-old patient has a pH of 7.28, PaCO₂ of 50 mmHg, and HCO₃⁻ of 24 mEq/L. What does this indicate?

Respiratory acidosis
B. Metabolic acidosis
C. Combined respiratory and metabolic acidosis
D. Compensated respiratory alkalosis

 

A high anion gap metabolic acidosis is most commonly associated with:

Acute diarrhea
B. Lactic acidosis
C. Hypoventilation
D. Vomiting

 

Which ABG finding is consistent with acute pulmonary embolism?

Respiratory alkalosis with hypoxemia
B. Metabolic acidosis with hyperoxemia
C. Respiratory acidosis with hypercapnia
D. Normal ABG values

 

The primary disturbance in metabolic acidosis is:

Increased PaCO₂
B. Decreased PaCO₂
C. Increased HCO₃⁻
D. Decreased HCO₃⁻

 

A patient presents with pH 7.48, PaCO₂ 30 mmHg, and HCO₃⁻ 22 mEq/L. What does this indicate?

Respiratory alkalosis
B. Metabolic alkalosis
C. Combined respiratory and metabolic alkalosis
D. Compensated metabolic acidosis

 

What is the expected compensation in chronic metabolic acidosis?

Increased HCO₃⁻ reabsorption by the kidneys
B. Increased respiratory rate to lower PaCO₂
C. Decreased respiratory rate to raise PaCO₂
D. No compensation occurs in metabolic acidosis

 

A patient with a history of COPD has pH 7.37, PaCO₂ 60 mmHg, and HCO₃⁻ 36 mEq/L. This represents:

Compensated respiratory acidosis
B. Compensated metabolic acidosis
C. Acute respiratory acidosis
D. Uncompensated metabolic alkalosis

 

A mixed respiratory and metabolic acidosis could be caused by:

Asthma exacerbation with renal failure
B. Hyperventilation due to anxiety
C. Vomiting and dehydration
D. Aspirin overdose

 

The arterial oxygen content (PaO₂) reflects:

Oxygen bound to hemoglobin and dissolved in plasma
B. Oxygen only bound to hemoglobin
C. Oxygen only dissolved in plasma
D. Carbon dioxide levels in arterial blood

 

A normal anion gap is most likely found in:

Lactic acidosis
B. Diabetic ketoacidosis
C. Renal tubular acidosis
D. Methanol poisoning

 

Which condition is most likely to result in metabolic alkalosis?

Severe diarrhea
B. Chronic kidney disease
C. Prolonged vomiting
D. Salicylate poisoning

 

An ABG result of pH 7.31, PaCO₂ 55 mmHg, and HCO₃⁻ 26 mEq/L indicates:

Metabolic acidosis
B. Respiratory acidosis
C. Mixed acidosis
D. Compensated respiratory alkalosis

 

A patient with septic shock develops a high anion gap acidosis. Likely causes include:

Increased lactate due to tissue hypoxia
B. Excessive bicarbonate loss through diarrhea
C. Hyperventilation
D. Excessive vomiting

 

Which of the following is the primary cause of metabolic acidosis with a normal anion gap?

Methanol ingestion
B. Renal tubular acidosis
C. Lactic acidosis
D. Diabetic ketoacidosis

 

A pH of 7.60, PaCO₂ 20 mmHg, and HCO₃⁻ 22 mEq/L would indicate:

Compensated metabolic alkalosis
B. Compensated respiratory alkalosis
C. Uncompensated respiratory alkalosis
D. Mixed respiratory and metabolic alkalosis

 

A patient is hypoxic with pH 7.50, PaCO₂ 30 mmHg, and HCO₃⁻ 24 mEq/L. What is the likely cause?

Anxiety-induced hyperventilation
B. COPD exacerbation
C. Acute renal failure
D. Aspirin toxicity

 

Which of the following ABG values suggests acute respiratory failure?

PaO₂ 90 mmHg, PaCO₂ 40 mmHg
B. PaO₂ 60 mmHg, PaCO₂ 60 mmHg
C. PaO₂ 80 mmHg, PaCO₂ 35 mmHg
D. PaO₂ 95 mmHg, PaCO₂ 45 mmHg

 

A patient presents with pH 7.20, PaCO₂ 60 mmHg, and HCO₃⁻ 28 mEq/L. This indicates:

Chronic respiratory acidosis with compensation
B. Acute respiratory acidosis without compensation
C. Metabolic acidosis
D. Mixed acidosis

 

Which ABG result is most consistent with hyperventilation syndrome?

pH 7.60, PaCO₂ 20 mmHg, HCO₃⁻ 22 mEq/L
B. pH 7.30, PaCO₂ 50 mmHg, HCO₃⁻ 26 mEq/L
C. pH 7.38, PaCO₂ 40 mmHg, HCO₃⁻ 24 mEq/L
D. pH 7.22, PaCO₂ 60 mmHg, HCO₃⁻ 28 mEq/L

 

What is the expected response in acute metabolic acidosis?

Hyperventilation to reduce PaCO₂
B. Hypoventilation to retain PaCO₂
C. Increased bicarbonate excretion
D. Decreased bicarbonate reabsorption

 

 

A patient with pH 7.46, PaCO₂ 32 mmHg, and HCO₃⁻ 20 mEq/L likely has which condition?

Compensated metabolic alkalosis
B. Compensated respiratory alkalosis
C. Partially compensated respiratory alkalosis
D. Uncompensated metabolic alkalosis

 

What is the expected PaCO₂ compensation for a metabolic acidosis with HCO₃⁻ of 16 mEq/L?

PaCO₂ = 40 mmHg
B. PaCO₂ = 32 mmHg
C. PaCO₂ = 28 mmHg
D. PaCO₂ = 24 mmHg

 

A patient has a pH of 7.25, PaCO₂ of 25 mmHg, and HCO₃⁻ of 15 mEq/L. What does this indicate?

Mixed acidosis
B. Metabolic acidosis with respiratory compensation
C. Respiratory acidosis with renal compensation
D. Compensated metabolic alkalosis

 

Which electrolyte imbalance is most often associated with metabolic alkalosis?

Hyperkalemia
B. Hypokalemia
C. Hypernatremia
D. Hyponatremia

 

Which of the following is a common cause of respiratory alkalosis?

Diabetic ketoacidosis
B. Hypoventilation due to opioid overdose
C. High-altitude exposure
D. Renal failure

 

The Winter’s formula helps predict compensatory PaCO₂ in:

Respiratory acidosis
B. Metabolic acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis

 

Which ABG value represents compensated metabolic alkalosis?

pH 7.48, PaCO₂ 48 mmHg, HCO₃⁻ 30 mEq/L
B. pH 7.42, PaCO₂ 47 mmHg, HCO₃⁻ 30 mEq/L
C. pH 7.32, PaCO₂ 50 mmHg, HCO₃⁻ 25 mEq/L
D. pH 7.36, PaCO₂ 30 mmHg, HCO₃⁻ 18 mEq/L

 

A patient has pH 7.50, PaCO₂ 52 mmHg, and HCO₃⁻ 40 mEq/L. This represents:

Metabolic alkalosis with respiratory compensation
B. Respiratory alkalosis with metabolic compensation
C. Uncompensated metabolic alkalosis
D. Mixed alkalosis

 

Which condition is most likely to cause a mixed metabolic and respiratory acidosis?

Sepsis with multi-organ failure
B. Hyperventilation due to anxiety
C. Chronic obstructive pulmonary disease (COPD)
D. Aspirin overdose

 

A 45-year-old patient has ABG values of pH 7.33, PaCO₂ 55 mmHg, and HCO₃⁻ 30 mEq/L. What is the most likely condition?

Chronic respiratory acidosis with compensation
B. Acute respiratory acidosis with no compensation
C. Metabolic alkalosis with compensation
D. Compensated metabolic acidosis

 

What ABG findings are consistent with acute salicylate poisoning?

Respiratory acidosis with hypoxemia
B. Metabolic acidosis and respiratory alkalosis
C. Metabolic alkalosis and respiratory acidosis
D. Normal ABG

 

In metabolic alkalosis due to vomiting, the expected ABG findings are:

High pH, low PaCO₂, high HCO₃⁻
B. Low pH, high PaCO₂, low HCO₃⁻
C. High pH, high PaCO₂, high HCO₃⁻
D. Normal pH, normal PaCO₂, high HCO₃⁻

 

An ABG showing pH 7.29, PaCO₂ 60 mmHg, and HCO₃⁻ 30 mEq/L indicates:

Acute respiratory acidosis
B. Compensated respiratory alkalosis
C. Chronic respiratory acidosis with compensation
D. Metabolic acidosis with respiratory compensation

 

Which is a hallmark of compensated respiratory alkalosis?

Decreased HCO₃⁻ with normal pH
B. Increased PaCO₂ with decreased HCO₃⁻
C. Increased HCO₃⁻ with decreased pH
D. Increased PaCO₂ with increased HCO₃⁻

 

What is the most likely cause of metabolic acidosis with an anion gap of 35 mEq/L?

Diarrhea
B. Acute renal failure
C. Aspirin overdose
D. Hyperaldosteronism

 

In diabetic ketoacidosis (DKA), the expected ABG pattern is:

Normal pH, high HCO₃⁻, and normal PaCO₂
B. Low pH, low HCO₃⁻, and low PaCO₂
C. Low pH, high HCO₃⁻, and low PaCO₂
D. High pH, high PaCO₂, and high HCO₃⁻

 

A mixed respiratory alkalosis and metabolic acidosis is often seen in:

Aspirin toxicity
B. Chronic obstructive pulmonary disease
C. Renal failure
D. Heart failure

 

A patient with Guillain-Barré syndrome is likely to develop which ABG pattern?

Respiratory alkalosis
B. Metabolic acidosis
C. Respiratory acidosis
D. Mixed acidosis

 

Which of the following ABG results indicates hyperventilation secondary to anxiety?

pH 7.50, PaCO₂ 28 mmHg, HCO₃⁻ 24 mEq/L
B. pH 7.32, PaCO₂ 50 mmHg, HCO₃⁻ 30 mEq/L
C. pH 7.28, PaCO₂ 60 mmHg, HCO₃⁻ 28 mEq/L
D. pH 7.44, PaCO₂ 40 mmHg, HCO₃⁻ 26 mEq/L

 

A patient with chronic kidney disease develops metabolic acidosis. The ABG would most likely show:

Decreased pH, decreased HCO₃⁻, and normal PaCO₂
B. Increased pH, decreased HCO₃⁻, and decreased PaCO₂
C. Normal pH, increased HCO₃⁻, and increased PaCO₂
D. Decreased pH, increased HCO₃⁻, and normal PaCO₂

 

 

What ABG pattern is expected in chronic obstructive pulmonary disease (COPD)?

Normal pH, low PaCO₂, low HCO₃⁻
B. Low pH, high PaCO₂, high HCO₃⁻
C. Normal pH, high PaCO₂, high HCO₃⁻
D. High pH, low PaCO₂, high HCO₃⁻

 

Which acid-base disorder is most likely in a patient with severe diarrhea?

Metabolic acidosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis

 

A patient has pH 7.60, PaCO₂ 20 mmHg, and HCO₃⁻ 22 mEq/L. The most likely cause is:

Acute anxiety attack
B. Diabetic ketoacidosis
C. Salicylate toxicity
D. Chronic kidney disease

 

What is the primary compensatory mechanism for metabolic alkalosis?

Hypoventilation to increase PaCO₂
B. Hyperventilation to decrease PaCO₂
C. Renal excretion of bicarbonate
D. Renal retention of hydrogen ions

 

A patient presents with pH 7.28, PaCO₂ 60 mmHg, and HCO₃⁻ 26 mEq/L. This indicates:

Uncompensated respiratory acidosis
B. Partially compensated metabolic acidosis
C. Mixed acidosis
D. Fully compensated respiratory acidosis

 

Which ABG finding suggests uncompensated metabolic acidosis?

pH 7.45, PaCO₂ 32 mmHg, HCO₃⁻ 19 mEq/L
B. pH 7.30, PaCO₂ 40 mmHg, HCO₃⁻ 18 mEq/L
C. pH 7.38, PaCO₂ 30 mmHg, HCO₃⁻ 17 mEq/L
D. pH 7.48, PaCO₂ 47 mmHg, HCO₃⁻ 34 mEq/L

 

In a patient with sepsis, ABG shows pH 7.20, PaCO₂ 25 mmHg, and HCO₃⁻ 10 mEq/L. What is the most likely diagnosis?

Lactic acidosis
B. Respiratory alkalosis
C. Metabolic alkalosis
D. Chronic respiratory acidosis

 

A patient with end-stage renal disease (ESRD) is likely to exhibit which ABG pattern?

High pH, low PaCO₂, low HCO₃⁻
B. Low pH, low PaCO₂, low HCO₃⁻
C. Normal pH, high PaCO₂, high HCO₃⁻
D. Low pH, normal PaCO₂, low HCO₃⁻

 

In metabolic acidosis with an anion gap, what is the primary unmeasured anion?

Albumin
B. Lactate
C. Chloride
D. Potassium

 

Which of the following ABG results is most consistent with acute respiratory alkalosis?

pH 7.48, PaCO₂ 30 mmHg, HCO₃⁻ 24 mEq/L
B. pH 7.31, PaCO₂ 50 mmHg, HCO₃⁻ 24 mEq/L
C. pH 7.38, PaCO₂ 38 mmHg, HCO₃⁻ 22 mEq/L
D. pH 7.50, PaCO₂ 55 mmHg, HCO₃⁻ 35 mEq/L

 

A patient with diabetic ketoacidosis has pH 7.15, PaCO₂ 20 mmHg, and HCO₃⁻ 8 mEq/L. What compensatory mechanism is occurring?

Renal excretion of hydrogen ions
B. Hyperventilation to lower PaCO₂
C. Retention of bicarbonate by kidneys
D. Respiratory compensation by hypoventilation

 

Which ABG pattern suggests mixed acidosis?

pH 7.28, PaCO₂ 55 mmHg, HCO₃⁻ 18 mEq/L
B. pH 7.36, PaCO₂ 45 mmHg, HCO₃⁻ 26 mEq/L
C. pH 7.45, PaCO₂ 30 mmHg, HCO₃⁻ 20 mEq/L
D. pH 7.32, PaCO₂ 40 mmHg, HCO₃⁻ 18 mEq/L

 

A 35-year-old patient has pH 7.41, PaCO₂ 26 mmHg, and HCO₃⁻ 16 mEq/L. What is the interpretation?

Uncompensated respiratory alkalosis
B. Fully compensated metabolic acidosis
C. Fully compensated respiratory alkalosis
D. Normal acid-base balance

 

In chronic respiratory alkalosis, what compensation is expected?

Decreased renal bicarbonate reabsorption
B. Increased renal bicarbonate reabsorption
C. Increased hydrogen ion secretion by the kidneys
D. Increased production of lactate

 

Which condition is most likely to cause metabolic alkalosis?

Loop diuretic therapy
B. Pulmonary embolism
C. Diabetic ketoacidosis
D. Sepsis

 

A patient presents with pH 7.54, PaCO₂ 28 mmHg, and HCO₃⁻ 24 mEq/L. The most likely cause is:

Acute respiratory alkalosis due to hyperventilation
B. Chronic metabolic alkalosis
C. Mixed alkalosis
D. Compensated respiratory alkalosis

 

Which compensatory response is expected in respiratory acidosis?

Renal retention of bicarbonate
B. Increased ventilation to reduce PaCO₂
C. Renal excretion of bicarbonate
D. Decreased production of hydrogen ions

 

A patient has a pH of 7.50, PaCO₂ 30 mmHg, and HCO₃⁻ 22 mEq/L. This ABG result suggests:

Acute respiratory alkalosis
B. Compensated metabolic alkalosis
C. Uncompensated metabolic acidosis
D. Fully compensated respiratory acidosis

 

The anion gap is calculated using which formula?

Na⁺ + K⁺ – (Cl⁻ + HCO₃⁻)
B. Na⁺ – (Cl⁻ + HCO₃⁻)
C. K⁺ – (Cl⁻ + HCO₃⁻)
D. Na⁺ – (Cl⁻ + HCO₃⁻ + K⁺)

 

A patient has the following ABG: pH 7.36, PaCO₂ 70 mmHg, and HCO₃⁻ 40 mEq/L. This pattern represents:

Fully compensated respiratory acidosis
B. Partially compensated metabolic acidosis
C. Mixed acidosis
D. Fully compensated metabolic acidosis

 

 

What ABG findings would you expect in a patient with aspirin overdose?

pH 7.50, PaCO₂ 20 mmHg, HCO₃⁻ 14 mEq/L
B. pH 7.30, PaCO₂ 50 mmHg, HCO₃⁻ 18 mEq/L
C. pH 7.60, PaCO₂ 40 mmHg, HCO₃⁻ 35 mEq/L
D. pH 7.40, PaCO₂ 30 mmHg, HCO₃⁻ 20 mEq/L

 

In metabolic acidosis, a normal anion gap suggests:

Renal tubular acidosis or diarrhea
B. Lactic acidosis or ketoacidosis
C. Aspirin overdose or methanol poisoning
D. Hypoventilation or chronic lung disease

 

A patient has pH 7.48, PaCO₂ 48 mmHg, and HCO₃⁻ 34 mEq/L. This ABG is consistent with:

Fully compensated respiratory alkalosis
B. Partially compensated metabolic alkalosis
C. Uncompensated respiratory acidosis
D. Mixed alkalosis

 

Which acid-base disorder is most commonly associated with vomiting?

Metabolic alkalosis
B. Metabolic acidosis
C. Respiratory acidosis
D. Respiratory alkalosis

 

A patient presents with pH 7.25, PaCO₂ 60 mmHg, and HCO₃⁻ 28 mEq/L. What is the interpretation?

Acute respiratory acidosis
B. Chronic respiratory acidosis with partial compensation
C. Mixed respiratory and metabolic acidosis
D. Metabolic alkalosis

 

Which ABG pattern indicates uncompensated metabolic alkalosis?

pH 7.55, PaCO₂ 40 mmHg, HCO₃⁻ 36 mEq/L
B. pH 7.30, PaCO₂ 50 mmHg, HCO₃⁻ 24 mEq/L
C. pH 7.44, PaCO₂ 32 mmHg, HCO₃⁻ 22 mEq/L
D. pH 7.60, PaCO₂ 60 mmHg, HCO₃⁻ 40 mEq/L

 

What is the expected pH range in a fully compensated acid-base disturbance?

7.00 to 7.20
B. 7.20 to 7.25
C. 7.35 to 7.45
D. 7.45 to 7.55

 

Which of the following conditions is most likely to cause respiratory alkalosis?

Chronic obstructive pulmonary disease (COPD)
B. Anxiety-induced hyperventilation
C. Pulmonary edema
D. Severe sepsis with lactic acidosis

 

A pH of 7.22, PaCO₂ of 65 mmHg, and HCO₃⁻ of 24 mEq/L suggests:

Acute respiratory acidosis without compensation
B. Acute respiratory acidosis with metabolic compensation
C. Chronic respiratory acidosis
D. Metabolic acidosis

 

A diabetic patient has pH 7.15, PaCO₂ 25 mmHg, and HCO₃⁻ 10 mEq/L. What acid-base abnormality is present?

Mixed metabolic acidosis and respiratory alkalosis
B. Metabolic acidosis with partial respiratory compensation
C. Respiratory alkalosis with metabolic compensation
D. Fully compensated metabolic acidosis

 

Which is the compensatory mechanism in respiratory alkalosis?

Increased renal hydrogen ion secretion
B. Decreased renal bicarbonate reabsorption
C. Increased respiratory rate
D. Increased bicarbonate buffer production

 

A patient has a PaO₂ of 50 mmHg, PaCO₂ of 60 mmHg, and pH of 7.30. What is the likely diagnosis?

Acute respiratory alkalosis
B. Chronic obstructive pulmonary disease (COPD) exacerbation
C. Pulmonary embolism
D. Metabolic acidosis

 

A normal anion gap metabolic acidosis is associated with which of the following?

Ketoacidosis
B. Diarrhea
C. Renal failure
D. Methanol poisoning

 

What does a widened anion gap in metabolic acidosis indicate?

Increased unmeasured anions like lactate or ketones
B. Decreased PaCO₂
C. Increased bicarbonate reabsorption
D. Chronic hypercapnia

 

A pH of 7.36, PaCO₂ of 28 mmHg, and HCO₃⁻ of 16 mEq/L is consistent with:

Uncompensated respiratory alkalosis
B. Compensated metabolic acidosis
C. Compensated metabolic alkalosis
D. Acute respiratory acidosis

 

Which of the following ABG results would suggest mixed acidosis?

pH 7.20, PaCO₂ 55 mmHg, HCO₃⁻ 18 mEq/L
B. pH 7.32, PaCO₂ 30 mmHg, HCO₃⁻ 16 mEq/L
C. pH 7.50, PaCO₂ 25 mmHg, HCO₃⁻ 20 mEq/L
D. pH 7.45, PaCO₂ 40 mmHg, HCO₃⁻ 26 mEq/L

 

Which ABG pattern is most consistent with aspirin toxicity in the early stages?

Respiratory acidosis
B. Respiratory alkalosis
C. Metabolic acidosis
D. Mixed metabolic acidosis and respiratory alkalosis

 

What is the normal range of the anion gap (without potassium)?

4 to 8 mEq/L
B. 8 to 12 mEq/L
C. 12 to 16 mEq/L
D. 16 to 20 mEq/L

 

In metabolic alkalosis, which electrolyte disturbance is most likely?

Hyperkalemia
B. Hypokalemia
C. Hypercalcemia
D. Hypernatremia

 

A patient’s ABG shows pH 7.33, PaCO₂ 30 mmHg, and HCO₃⁻ 15 mEq/L. What is the likely acid-base disorder?

Fully compensated respiratory alkalosis
B. Partially compensated metabolic acidosis
C. Uncompensated metabolic acidosis
D. Mixed acidosis

 

A patient with severe diarrhea presents with pH 7.25, PaCO₂ 38 mmHg, and HCO₃⁻ 18 mEq/L. What is the acid-base disorder?

Metabolic acidosis without compensation
B. Metabolic acidosis with respiratory compensation
C. Mixed acidosis
D. Respiratory acidosis with metabolic compensation

 

Which of the following ABG findings is consistent with acute respiratory acidosis?

pH 7.30, PaCO₂ 50 mmHg, HCO₃⁻ 24 mEq/L
B. pH 7.50, PaCO₂ 30 mmHg, HCO₃⁻ 24 mEq/L
C. pH 7.40, PaCO₂ 60 mmHg, HCO₃⁻ 36 mEq/L
D. pH 7.35, PaCO₂ 60 mmHg, HCO₃⁻ 30 mEq/L

 

What acid-base disturbance is typically seen in a patient with sepsis and elevated lactate levels?

Respiratory acidosis
B. Metabolic acidosis with a high anion gap
C. Metabolic alkalosis
D. Respiratory alkalosis

 

A mixed acid-base disorder with metabolic alkalosis and respiratory acidosis might occur in which condition?

Chronic obstructive pulmonary disease (COPD) with vomiting
B. Severe asthma with diarrhea
C. Diabetic ketoacidosis with renal failure
D. Aspirin overdose

 

Which ABG result is most consistent with hyperventilation syndrome?

pH 7.48, PaCO₂ 28 mmHg, HCO₃⁻ 22 mEq/L
B. pH 7.30, PaCO₂ 50 mmHg, HCO₃⁻ 28 mEq/L
C. pH 7.36, PaCO₂ 40 mmHg, HCO₃⁻ 24 mEq/L
D. pH 7.20, PaCO₂ 60 mmHg, HCO₃⁻ 24 mEq/L

 

Which condition can cause both respiratory alkalosis and metabolic acidosis simultaneously?

Pulmonary embolism
B. Salicylate toxicity
C. Renal tubular acidosis
D. Diabetic ketoacidosis

 

A pH of 7.55, PaCO₂ 50 mmHg, and HCO₃⁻ 40 mEq/L is indicative of:

Partially compensated metabolic alkalosis
B. Partially compensated respiratory alkalosis
C. Mixed alkalosis
D. Fully compensated metabolic alkalosis

 

What would you expect in ABG results for a patient with acute pulmonary edema?

pH 7.30, PaCO₂ 60 mmHg, HCO₃⁻ 24 mEq/L
B. pH 7.50, PaCO₂ 28 mmHg, HCO₃⁻ 22 mEq/L
C. pH 7.40, PaCO₂ 40 mmHg, HCO₃⁻ 24 mEq/L
D. pH 7.25, PaCO₂ 45 mmHg, HCO₃⁻ 20 mEq/L

 

In a patient with severe metabolic acidosis, which compensatory mechanism is expected?

Hyperventilation to decrease PaCO₂
B. Increased renal excretion of HCO₃⁻
C. Hypoventilation to increase PaCO₂
D. Increased renal reabsorption of PaCO₂

 

A patient with pH 7.32, PaCO₂ 50 mmHg, and HCO₃⁻ 28 mEq/L likely has:

Uncompensated respiratory acidosis
B. Partially compensated respiratory acidosis
C. Metabolic alkalosis with compensation
D. Mixed respiratory and metabolic alkalosis

 

A normal PaO₂ on room air is approximately:

50-70 mmHg
B. 75-100 mmHg
C. 100-150 mmHg
D. 150-200 mmHg

 

What acid-base abnormality is expected in a patient with diabetic ketoacidosis (DKA)?

Metabolic alkalosis
B. Metabolic acidosis with high anion gap
C. Respiratory acidosis
D. Metabolic acidosis with normal anion gap

 

A pH of 7.28, PaCO₂ of 55 mmHg, and HCO₃⁻ of 25 mEq/L suggests:

Acute respiratory acidosis without compensation
B. Acute respiratory acidosis with partial compensation
C. Chronic respiratory acidosis
D. Mixed metabolic and respiratory acidosis

 

Which condition is most likely to cause respiratory acidosis?

Panic attack
B. Chronic obstructive pulmonary disease (COPD)
C. Diarrhea
D. Vomiting

 

A high anion gap metabolic acidosis is commonly associated with:

Severe vomiting
B. Renal tubular acidosis
C. Methanol poisoning
D. Hyperventilation

 

The ABG results of pH 7.48, PaCO₂ 45 mmHg, and HCO₃⁻ 30 mEq/L suggest:

Uncompensated metabolic alkalosis
B. Fully compensated metabolic alkalosis
C. Uncompensated respiratory alkalosis
D. Mixed metabolic and respiratory alkalosis

 

What is the compensatory response to metabolic acidosis?

Increased respiratory rate to lower PaCO₂
B. Increased PaCO₂ to raise pH
C. Increased renal reabsorption of HCO₃⁻
D. Decreased respiratory rate to increase PaCO₂

 

A PaCO₂ level below 35 mmHg typically indicates:

Hypoventilation
B. Hyperventilation
C. Metabolic alkalosis
D. Mixed acidosis

 

A pH of 7.22, PaCO₂ of 22 mmHg, and HCO₃⁻ of 12 mEq/L suggests which primary acid-base abnormality?

Uncompensated metabolic acidosis
B. Partially compensated metabolic acidosis
C. Respiratory acidosis
D. Mixed respiratory and metabolic acidosis

 

A patient presents with an ABG of pH 7.50, PaCO₂ 25 mmHg, and HCO₃⁻ 22 mEq/L. What is the likely diagnosis?

Acute respiratory alkalosis
B. Compensated respiratory acidosis
C. Uncompensated metabolic alkalosis
D. Mixed alkalosis

 

 

A 35-year-old male presents with pH 7.28, PaCO₂ 65 mmHg, and HCO₃⁻ 25 mEq/L. What is the most likely cause of this imbalance?

Severe asthma exacerbation
B. Acute renal failure
C. Salicylate overdose
D. Gastrointestinal loss of bicarbonate

 

A patient with an opioid overdose has the following ABG results: pH 7.20, PaCO₂ 75 mmHg, and HCO₃⁻ 26 mEq/L. What is the primary acid-base disorder?

Metabolic acidosis
B. Respiratory acidosis
C. Mixed acidosis
D. Respiratory alkalosis

 

A 28-year-old female with acute anxiety is hyperventilating. Her ABG results are: pH 7.55, PaCO₂ 22 mmHg, and HCO₃⁻ 24 mEq/L. What is the acid-base diagnosis?

Acute respiratory alkalosis
B. Chronic respiratory alkalosis
C. Metabolic alkalosis
D. Mixed alkalosis

 

A patient with chronic kidney disease presents with pH 7.32, PaCO₂ 35 mmHg, and HCO₃⁻ 18 mEq/L. What compensatory mechanism is expected?

Decreased respiratory rate to retain CO₂
B. Increased respiratory rate to lower CO₂
C. Increased renal reabsorption of bicarbonate
D. Increased renal excretion of bicarbonate

 

A 65-year-old COPD patient on 2L/min oxygen has the following ABG: pH 7.36, PaCO₂ 55 mmHg, and HCO₃⁻ 30 mEq/L. What is the interpretation?

Acute respiratory acidosis
B. Chronic respiratory acidosis with compensation
C. Metabolic acidosis
D. Mixed respiratory and metabolic acidosis

 

A patient is found unconscious with ABG showing pH 7.15, PaCO₂ 30 mmHg, and HCO₃⁻ 10 mEq/L. What is the most likely underlying disorder?

Severe metabolic acidosis with respiratory compensation
B. Severe respiratory acidosis with metabolic compensation
C. Mixed respiratory and metabolic acidosis
D. Metabolic alkalosis

 

Which condition is most consistent with the following ABG: pH 7.60, PaCO₂ 40 mmHg, and HCO₃⁻ 38 mEq/L?

Metabolic alkalosis without compensation
B. Respiratory alkalosis
C. Fully compensated metabolic alkalosis
D. Mixed alkalosis

 

A 45-year-old patient with severe vomiting has ABG results: pH 7.50, PaCO₂ 48 mmHg, and HCO₃⁻ 34 mEq/L. What is the diagnosis?

Metabolic alkalosis with partial respiratory compensation
B. Respiratory alkalosis with compensation
C. Mixed respiratory and metabolic alkalosis
D. Uncompensated metabolic acidosis

 

A patient with diabetic ketoacidosis receives ABG results: pH 7.20, PaCO₂ 25 mmHg, and HCO₃⁻ 10 mEq/L. What compensation is present?

Respiratory alkalosis compensating for metabolic acidosis
B. Metabolic alkalosis compensating for respiratory acidosis
C. Fully compensated metabolic acidosis
D. No compensation present

 

A marathon runner collapses with severe dehydration. Her ABG shows: pH 7.30, PaCO₂ 40 mmHg, and HCO₃⁻ 18 mEq/L. What type of acidosis is this?

Respiratory acidosis
B. Metabolic acidosis without compensation
C. Metabolic acidosis with no respiratory compensation
D. Metabolic acidosis with respiratory compensation

 

ABG for a post-operative patient under shallow ventilation is: pH 7.28, PaCO₂ 48 mmHg, and HCO₃⁻ 24 mEq/L. What does this suggest?

Acute respiratory acidosis
B. Chronic respiratory acidosis
C. Metabolic acidosis
D. Mixed acidosis

 

A patient with sepsis has ABG results of pH 7.18, PaCO₂ 32 mmHg, and HCO₃⁻ 12 mEq/L. What is the expected anion gap?

Normal anion gap (8-12 mEq/L)
B. Elevated anion gap (>12 mEq/L)
C. Decreased anion gap (<8 mEq/L)
D. No correlation with anion gap

 

A patient with Guillain-Barré syndrome develops hypoventilation. What ABG abnormality would you expect?

Metabolic alkalosis
B. Respiratory acidosis
C. Metabolic acidosis
D. Respiratory alkalosis

 

What primary acid-base imbalance is expected in a patient with prolonged NG suction?

Metabolic alkalosis
B. Respiratory acidosis
C. Metabolic acidosis
D. Respiratory alkalosis

 

A 40-year-old female with aspirin overdose has ABG showing: pH 7.50, PaCO₂ 30 mmHg, and HCO₃⁻ 20 mEq/L. What type of imbalance is this?

Mixed respiratory alkalosis and metabolic acidosis
B. Respiratory acidosis with partial compensation
C. Uncompensated metabolic alkalosis
D. Compensated respiratory acidosis

 

What is the most likely diagnosis for a pH of 7.38, PaCO₂ of 55 mmHg, and HCO₃⁻ of 32 mEq/L in a COPD patient?

Acute respiratory acidosis
B. Fully compensated respiratory acidosis
C. Metabolic acidosis
D. Mixed respiratory and metabolic acidosis

 

In a patient with severe diarrhea, ABG results show pH 7.25, PaCO₂ 38 mmHg, and HCO₃⁻ 15 mEq/L. What is the likely acid-base disorder?

Non-anion gap metabolic acidosis
B. High anion gap metabolic acidosis
C. Respiratory acidosis
D. Mixed metabolic and respiratory acidosis

 

A patient with carbon monoxide poisoning has normal ABG values. Why might this occur?

CO affects hemoglobin saturation but not PaO₂
B. CO increases PaO₂ while lowering pH
C. CO raises bicarbonate without affecting PaCO₂
D. CO exclusively impacts ventilation rates

 

A 65-year-old male with a history of COPD presents to the ER with increasing shortness of breath. His ABG shows: pH 7.31, PaCO₂ 70 mmHg, and HCO₃⁻ 28 mEq/L. What is the most likely diagnosis?

Acute respiratory acidosis with partial compensation
B. Chronic respiratory acidosis with full compensation
C. Acute metabolic acidosis with respiratory compensation
D. Respiratory alkalosis

 

A 30-year-old female presents with hyperventilation following a panic attack. Her ABG results show: pH 7.49, PaCO₂ 25 mmHg, and HCO₃⁻ 24 mEq/L. What is the interpretation?

Acute respiratory alkalosis
B. Chronic respiratory alkalosis
C. Metabolic alkalosis
D. Acute respiratory acidosis

 

A patient with diabetic ketoacidosis (DKA) has the following ABG results: pH 7.25, PaCO₂ 30 mmHg, and HCO₃⁻ 12 mEq/L. What is the most likely acid-base disturbance?

Metabolic acidosis with respiratory compensation
B. Respiratory acidosis with metabolic compensation
C. Metabolic alkalosis
D. Respiratory alkalosis

 

A 75-year-old male is admitted with pneumonia. His ABG shows: pH 7.31, PaCO₂ 55 mmHg, and HCO₃⁻ 28 mEq/L. What is the interpretation?

Acute respiratory acidosis with compensation
B. Chronic respiratory acidosis
C. Metabolic acidosis
D. Respiratory alkalosis

 

A patient with severe vomiting has the following ABG results: pH 7.48, PaCO₂ 48 mmHg, and HCO₃⁻ 36 mEq/L. What is the diagnosis?

Metabolic alkalosis with respiratory compensation
B. Acute respiratory acidosis
C. Mixed respiratory and metabolic alkalosis
D. Chronic respiratory alkalosis

 

A 40-year-old female presents with dizziness and chest pain. ABG results show: pH 7.52, PaCO₂ 30 mmHg, and HCO₃⁻ 22 mEq/L. What is the interpretation?

Respiratory alkalosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Mixed acidosis

 

A patient presents with profound fatigue and confusion. Her ABG shows: pH 7.17, PaCO₂ 20 mmHg, and HCO₃⁻ 8 mEq/L. What is the most likely cause of this acid-base disturbance?

Severe metabolic acidosis with respiratory compensation
B. Respiratory alkalosis
C. Metabolic alkalosis
D. Respiratory acidosis

 

A 60-year-old male with chronic kidney disease presents with confusion and drowsiness. His ABG results show: pH 7.30, PaCO₂ 50 mmHg, and HCO₃⁻ 18 mEq/L. What is the diagnosis?

Chronic respiratory acidosis
B. Metabolic acidosis with respiratory compensation
C. Respiratory alkalosis
D. Mixed acidosis

 

A 50-year-old patient with severe diarrhea presents with the following ABG results: pH 7.34, PaCO₂ 40 mmHg, and HCO₃⁻ 16 mEq/L. What is the interpretation?

Non-anion gap metabolic acidosis
B. High anion gap metabolic acidosis
C. Respiratory alkalosis
D. Metabolic alkalosis

 

A patient with acute kidney failure has the following ABG: pH 7.25, PaCO₂ 38 mmHg, and HCO₃⁻ 14 mEq/L. What is the diagnosis?

Metabolic acidosis with respiratory compensation
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis

 

True & False

 

1. A normal pH range for arterial blood is between 7.35 and 7.45.

Answer:

2. A PaCO₂ value greater than 45 mmHg indicates respiratory alkalosis.

Answer:

3. In metabolic acidosis, bicarbonate (HCO₃⁻) levels are typically elevated.

Answer:

4. Respiratory compensation for metabolic acidosis leads to an increase in PaCO₂.

Answer:

5. In metabolic alkalosis, the pH is typically below 7.35.

Answer:

6. A PaCO₂ value below 35 mmHg is a characteristic sign of respiratory alkalosis.

Answer:

7. Lactic acidosis results from a buildup of lactate in the blood due to anaerobic metabolism.

Answer:

8. Diabetic ketoacidosis (DKA) typically results in metabolic alkalosis.

Answer:

9. The body compensates for respiratory acidosis by increasing ventilation and exhaling more CO₂.

Answer:

10. In respiratory alkalosis, the bicarbonate (HCO₃⁻) level is typically decreased.

Answer:

11. Chronic respiratory acidosis can lead to renal compensation, resulting in increased bicarbonate (HCO₃⁻) levels.

Answer:

12. Hyperventilation can result in respiratory acidosis.

Answer:

13. In metabolic acidosis, the primary disturbance is a decrease in bicarbonate (HCO₃⁻).

Answer:

14. In respiratory alkalosis, the body tries to compensate by retaining hydrogen ions (H⁺).

Answer:

15. The PaO₂ (partial pressure of oxygen) value is typically unrelated to pH balance.

Answer: True – PaO₂ measures oxygen levels and is not directly involved in acid-base balance, unlike PaCO₂ and bicarbonate.

16. An ABG with a low pH, elevated PaCO₂, and low bicarbonate (HCO₃⁻) would indicate mixed respiratory acidosis and metabolic acidosis.

Answer:

17. In metabolic acidosis, the body compensates by decreasing the respiratory rate to retain CO₂.

Answer:

18. ABG results in renal failure typically show respiratory alkalosis due to increased CO₂ elimination.

Answer:

19. The primary respiratory compensation mechanism in metabolic alkalosis is hypoventilation.

Answer:

20. Acute respiratory acidosis can be corrected through renal compensation, but this takes several hours to days.

Answer:

21. The presence of low bicarbonate (HCO₃⁻) and elevated PaCO₂ suggests a metabolic alkalosis disorder.

Answer:

22. A PaCO₂ value of 30 mmHg suggests respiratory alkalosis.

Answer:

23. Hypercapnia, or an elevated PaCO₂, is commonly seen in metabolic alkalosis.

Answer:

24. In diabetic ketoacidosis, an ABG would show metabolic acidosis with a compensatory respiratory alkalosis.

Answer:

25. A PaCO₂ value of 55 mmHg would indicate metabolic alkalosis.

Answer:

26. Hyperventilation causes a decrease in PaCO₂ and can lead to respiratory alkalosis.

Answer:

27. A decrease in pH and a decrease in PaCO₂ suggest respiratory acidosis.

Answer:

28. Mixed acid-base disorders are not possible in ABG interpretation.

Answer:

29. In chronic respiratory acidosis, the kidneys compensate by retaining bicarbonate to buffer the excess CO₂.

Answer:

30. In metabolic acidosis, hyperventilation is a compensatory mechanism to increase pH.

Answer:

 

Questions and Answers for Study Guide

 

Explain the process of compensatory mechanisms in acid-base balance. How do the respiratory and renal systems respond to metabolic and respiratory disturbances?

Answer:

Compensatory mechanisms in acid-base balance help restore the body’s normal pH (7.35–7.45) when disrupted by acid-base disturbances. The two primary systems involved in compensation are the respiratory system and the renal system.

• Respiratory Compensation: The lungs respond to changes in blood pH by adjusting the levels of carbon dioxide (CO₂). When the body is in respiratory acidosis (elevated CO₂), the kidneys compensate by retaining bicarbonate (HCO₃⁻) to buffer the excess acid. In respiratory alkalosis (low CO₂), the kidneys excrete bicarbonate to balance the pH.
• Renal Compensation: The kidneys play a slower but more long-term role. They compensate for metabolic acidosis (low HCO₃⁻) by increasing HCO₃⁻ retention and excreting excess hydrogen ions (H⁺). In metabolic alkalosis (high HCO₃⁻), the kidneys excrete bicarbonate and retain hydrogen ions to bring the pH back to normal.

The speed and effectiveness of compensation depend on the type of disturbance and the body’s ability to respond.

 

Discuss the clinical significance of interpreting the anion gap in diagnosing metabolic acidosis. How does an increased anion gap help in identifying the underlying cause?

Answer:

The anion gap is a calculation used to help identify the cause of metabolic acidosis. It is calculated by subtracting the sum of chloride (Cl⁻) and bicarbonate (HCO₃⁻) from the sodium (Na⁺) concentration in blood:

Anion Gap = Na⁺ – (Cl⁻ + HCO₃⁻)

• A normal anion gap is typically between 8-12 mEq/L, although this can vary slightly depending on the lab.
• An increased anion gap (greater than 12 mEq/L) indicates the presence of accumulation of unmeasured acids in the blood, such as in diabetic ketoacidosis (DKA), lactic acidosis, uremia, or ingestion of toxins (e.g., methanol, ethylene glycol).
• Normal anion gap metabolic acidosis occurs when the loss of bicarbonate is compensated by an increase in chloride levels, commonly seen in diarrhea or renal tubular acidosis.

An increased anion gap helps clinicians narrow down the potential causes of metabolic acidosis and guide treatment strategies.

 

Describe the role of Arterial Blood Gas (ABG) analysis in managing patients with respiratory diseases such as COPD. What are the typical ABG findings in a patient with acute exacerbation of COPD?

Answer:

Arterial Blood Gas (ABG) analysis plays a critical role in monitoring and managing patients with respiratory diseases, including chronic obstructive pulmonary disease (COPD). COPD, characterized by chronic airflow limitation, can lead to both respiratory acidosis and respiratory alkalosis, depending on the stage of the disease.

• Typical ABG Findings in Acute Exacerbation of COPD:
  • Respiratory acidosis is common in patients with acute exacerbation of COPD. The hallmark of this condition is elevated PaCO₂ (partial pressure of carbon dioxide), usually above 45 mmHg, which occurs due to hypoventilation and the inability of the lungs to effectively remove CO₂.
  • The pH will often be low (below 7.35), indicating acidosis.
  • HCO₃⁻ (bicarbonate) levels may be elevated as a compensatory response from the kidneys, though this compensation is often insufficient during acute exacerbations.
• In severe cases, respiratory failure can occur, necessitating mechanical ventilation to manage CO₂ levels and support the respiratory system.

ABG analysis helps guide therapy, including oxygen supplementation and ventilatory support, to correct the imbalance and improve gas exchange.

 

What is the pathophysiology of diabetic ketoacidosis (DKA) and how is it reflected in ABG results? Discuss the management strategies for correcting the acid-base disturbance in DKA.

Answer:

Diabetic ketoacidosis (DKA) is a life-threatening complication of diabetes mellitus (especially type 1 diabetes) that occurs due to insulin deficiency and increased counter-regulatory hormones (glucagon, cortisol, catecholamines). This leads to the breakdown of fat for energy, producing ketone bodies (acetoacetate, beta-hydroxybutyrate), which causes metabolic acidosis.

• ABG Findings in DKA:
  • Low pH (below 7.35), indicating acidosis.
  • Low bicarbonate (HCO₃⁻), often less than 15 mEq/L, due to the buffering of ketones in the blood.
  • The PaCO₂ may be low (often below 35 mmHg) due to respiratory compensation (Kussmaul respirations), a deep, labored breathing pattern aimed at exhaling CO₂ to raise pH.

Management of DKA:

• Fluids: To correct dehydration caused by osmotic diuresis and to improve circulation.
• Insulin therapy: To reduce blood glucose levels and stop ketone production.
• Electrolyte replacement: Especially potassium, as insulin therapy can shift potassium into cells, potentially leading to hypokalemia.
• Monitor ABG and blood glucose levels frequently to assess the correction of the acidosis and the overall clinical condition.

The goal is to correct the acidosis gradually, avoiding rapid changes in pH that could lead to complications such as cerebral edema.

 

How does hyperventilation cause respiratory alkalosis? Discuss the clinical scenarios in which hyperventilation may occur and how ABG results can guide management.

Answer:

Hyperventilation occurs when a patient breathes excessively, leading to excessive CO₂ removal from the body. This results in respiratory alkalosis due to the decreased PaCO₂ (partial pressure of carbon dioxide) in the blood.

• Pathophysiology of Respiratory Alkalosis:
  • The primary disturbance is a decrease in PaCO₂, typically below 35 mmHg.
  • The decrease in PaCO₂ raises the pH of the blood, leading to alkalosis (pH above 7.45).
  • The kidneys may attempt to compensate by excreting bicarbonate (HCO₃⁻), but this compensatory mechanism is usually slower, taking hours to days.
• Clinical Scenarios Leading to Hyperventilation:
  • Panic attacks or anxiety: Patients may hyperventilate due to acute stress, leading to respiratory alkalosis.
  • Hypoxemia: Conditions like pulmonary embolism or high-altitude exposure can lead to increased breathing rates to compensate for low oxygen levels.
  • Sepsis or fever: These conditions can increase the respiratory rate, leading to a drop in CO₂.

ABG findings:

• Low PaCO₂ and elevated pH.
• Compensation may be noted as a decrease in HCO₃⁻.

Management:

• In anxiety or panic attacks, reassurance and controlled breathing can help. In other cases, treating the underlying condition (e.g., oxygen for hypoxemia) is essential to correct the acid-base imbalance.

 

Discuss the role of the kidneys in compensating for respiratory acidosis. How do they help restore normal pH, and what changes can be observed in ABG values?

Answer:

In respiratory acidosis, the primary issue is elevated CO₂ levels, typically due to hypoventilation or impaired gas exchange, which leads to an accumulation of carbonic acid in the blood. The kidneys help compensate for this disturbance by adjusting the bicarbonate (HCO₃⁻) levels over a period of hours to days.

• Kidney Compensation Mechanism:
  • The kidneys compensate by retaining bicarbonate to neutralize the excess hydrogen ions (H⁺) produced by the high CO₂ levels. They do this by reabsorbing bicarbonate from the urine and generating new bicarbonate ions.
  • The kidneys also excrete hydrogen ions into the urine, further contributing to the compensation for acidosis.
• ABG Findings:
  • Low pH (below 7.35) due to respiratory acidosis.
  • Elevated PaCO₂ (greater than 45 mmHg) indicating hypoventilation.
  • Elevated bicarbonate (HCO₃⁻) after compensatory renal response, though this compensation may not be fully achieved in acute settings.

Management: The underlying cause of respiratory acidosis (such as obstructive lung disease or respiratory depression) must be treated. Mechanical ventilation may be required in severe cases to assist with CO₂ removal.

 

Describe the physiological changes that occur in metabolic acidosis and how respiratory compensation helps to mitigate these changes. What are some of the causes of metabolic acidosis that may be identified through ABG interpretation?

Answer:

Metabolic acidosis occurs when there is an excess of acid in the blood or a loss of bicarbonate, leading to a decrease in pH. This may be due to conditions such as diabetic ketoacidosis (DKA), lactic acidosis, chronic kidney disease, or ingestion of toxins.

• Pathophysiology of Metabolic Acidosis:
  • The body’s pH decreases due to excess hydrogen ions (H⁺) or loss of bicarbonate (HCO₃⁻).
  • The lungs compensate by hyperventilating to expel CO₂ (since CO₂ combines with water to form carbonic acid, which lowers pH). This results in decreased PaCO₂, which partially compensates for the acidosis.
  • The kidneys may also attempt to compensate by increasing bicarbonate reabsorption and excreting hydrogen ions.
• ABG Findings:
  • Low pH (below 7.35) due to acidosis.
  • Low bicarbonate (HCO₃⁻) (typically less than 22 mEq/L).
  • Low PaCO₂ (less than 35 mmHg) as a result of respiratory compensation (hyperventilation).
• Causes of Metabolic Acidosis:
  • Diabetic Ketoacidosis (DKA): High ketones in the blood cause a drop in bicarbonate.
  • Lactic Acidosis: Accumulation of lactic acid from conditions like sepsis or hypoxia.
  • Renal Failure: Inability to excrete acids properly.
  • Toxins: Ingestion of substances like methanol, ethylene glycol, or aspirin.

Management: Treatment focuses on addressing the underlying cause. For example, insulin therapy for DKA, sodium bicarbonate for severe acidosis, or oxygen therapy for lactic acidosis.

 

Explain how respiratory alkalosis can occur in a patient with severe anxiety. What physiological changes occur in the body, and how can ABG analysis aid in diagnosis and management?

Answer:

Respiratory alkalosis occurs when a person hyperventilates, leading to excessive exhalation of CO₂. This causes a decrease in PaCO₂, which raises the pH of the blood, resulting in alkalosis. Hyperventilation due to severe anxiety or panic attacks is a common cause of this condition.

• Pathophysiology of Respiratory Alkalosis:
  • Hyperventilation leads to excessive loss of CO₂, which in turn reduces the concentration of hydrogen ions (H⁺) in the blood, raising the pH.
  • Compensatory Mechanism: The kidneys respond by excreting bicarbonate (HCO₃⁻) to reduce the buffering capacity and lower the pH back toward normal levels. However, this compensatory response is slow and may take several hours to be effective.
• ABG Findings:
  • Elevated pH (above 7.45), indicating alkalosis.
  • Low PaCO₂ (less than 35 mmHg) due to hyperventilation.
  • Normal or low bicarbonate (HCO₃⁻), depending on the stage of compensation.
• Management:
  • In cases of severe anxiety or panic attacks, reassurance and controlled breathing (slow, deep breaths) are essential in reducing the rate of hyperventilation.
  • If anxiety is chronic, treatment of the underlying anxiety disorder with cognitive-behavioral therapy (CBT) or medications (e.g., anxiolytics) may be necessary.

Discuss the interpretation of ABG results in a patient with chronic kidney disease (CKD). How does CKD lead to metabolic acidosis, and what ABG findings would you expect to see in such patients?

Answer:

In chronic kidney disease (CKD), the kidneys lose their ability to effectively excrete hydrogen ions (H⁺) and reabsorb bicarbonate (HCO₃⁻), leading to metabolic acidosis.

• Pathophysiology of Metabolic Acidosis in CKD:
  • As kidney function declines, the kidneys become less able to filter acids and retain bicarbonate, resulting in the accumulation of acid in the blood and a drop in bicarbonate levels.
  • Additionally, CKD can impair the kidneys’ ability to excrete phosphate and urea, which can also contribute to acidosis.
• ABG Findings in CKD:
  • Low pH (below 7.35), indicating acidosis.
  • Low bicarbonate (HCO₃⁻) (typically below 22 mEq/L), due to impaired renal buffering.
  • Normal PaCO₂ or slightly low PaCO₂, as compensation is slower in CKD.
• Management:
  • Sodium bicarbonate may be administered to help increase bicarbonate levels and correct the acidosis.
  • Dialysis may be necessary in advanced stages of CKD to help manage acid-base disturbances.
  • Phosphate binders may also be used to address the accumulation of phosphate.

 

How does the interpretation of ABG results guide the treatment of a patient with a severe asthma attack? Discuss the expected ABG findings and how respiratory acidosis may develop in such a case.

Answer:

A severe asthma attack leads to airway obstruction, making it difficult for the patient to exhale CO₂, which can result in respiratory acidosis if left untreated. This condition is characterized by a decrease in the ability to eliminate CO₂, leading to its accumulation in the blood.

• Pathophysiology of Respiratory Acidosis in Asthma:
  • During an asthma attack, the bronchial constriction and inflammation impair airflow, leading to CO₂ retention.
  • As the PaCO₂ rises, the pH decreases, causing respiratory acidosis.
  • In the early stages, hyperventilation may occur as a compensatory mechanism, but as the condition worsens, the ability to compensate diminishes.
• ABG Findings:
  • Low pH (below 7.35) due to acidosis.
  • Elevated PaCO₂ (greater than 45 mmHg) reflecting CO₂ retention.
  • Normal or slightly low bicarbonate (HCO₃⁻), depending on the stage of compensation (kidneys may begin to retain bicarbonate to buffer the acid).
• Management:
  • Inhaled bronchodilators (e.g., albuterol) are given to relieve bronchospasm and improve airflow.
  • Systemic corticosteroids may be used to reduce inflammation and prevent further exacerbation.
  • Oxygen therapy is used to address hypoxemia, and mechanical ventilation may be required in severe cases.

 

How does an acute exacerbation of chronic obstructive pulmonary disease (COPD) lead to respiratory acidosis, and what role does ABG analysis play in guiding treatment?

Answer:

In patients with chronic obstructive pulmonary disease (COPD), the lungs’ ability to exchange gases is compromised, which makes it difficult to expel carbon dioxide (CO₂) effectively. During an acute exacerbation of COPD, the respiratory system becomes overwhelmed, leading to hypoventilation, air trapping, and increased CO₂ retention, which results in respiratory acidosis.

• Pathophysiology:
  • In COPD, the chronic airflow obstruction reduces the lung’s ability to clear CO₂. During an acute exacerbation, respiratory drive becomes insufficient, further impairing gas exchange and causing CO₂ retention.
  • The body’s compensatory mechanism involves the kidneys, which gradually attempt to compensate for acidosis by retaining bicarbonate (HCO₃⁻) and excreting hydrogen ions (H⁺).
• ABG Findings:
  • Low pH (below 7.35) due to the accumulation of CO₂, leading to acidosis.
  • Elevated PaCO₂ (greater than 45 mmHg) indicating hypoventilation and CO₂ retention.
  • Normal or slightly elevated bicarbonate (HCO₃⁻) as the kidneys try to compensate, but this response is slow.
• Treatment:
  • The goal is to improve ventilation and reduce CO₂ retention. Bronchodilators, steroids, and antibiotics (if an infection is present) are administered.
  • In severe cases, non-invasive positive pressure ventilation (NIPPV) or mechanical ventilation may be necessary to support the patient’s breathing and prevent further deterioration.

 

Discuss the implications of metabolic alkalosis in a patient with excessive vomiting. How does vomiting affect acid-base balance, and what ABG findings would you expect to see?

Answer:

Metabolic alkalosis often results from excessive vomiting, which leads to the loss of hydrogen ions (H⁺) and chloride from the stomach. This causes an imbalance in the acid-base equilibrium, raising the blood’s pH and causing alkalosis.

• Pathophysiology of Vomiting-Induced Alkalosis:
  • Vomiting leads to the loss of stomach acid (HCl), which contains hydrogen ions. As a result, the blood becomes less acidic (alkalotic).
  • The kidneys compensate by decreasing bicarbonate excretion and increasing hydrogen ion retention in the urine to help restore balance.
• ABG Findings:
  • Elevated pH (greater than 7.45) indicating alkalosis.
  • Elevated bicarbonate (HCO₃⁻) (greater than 28 mEq/L), a compensatory response by the kidneys to neutralize the loss of H⁺ ions.
  • Normal or low PaCO₂ (below 35 mmHg), as the respiratory system compensates by decreasing CO₂ through hyperventilation.
• Management:
  • Fluid and electrolyte replacement is crucial to restore the lost potassium and chloride, as well as to correct the alkalosis.
  • Anti-emetic drugs may be administered to reduce vomiting, and treating the underlying cause (e.g., gastric outlet obstruction or gastrointestinal disease) is essential.

 

Explain the ABG interpretation in a patient with diabetic ketoacidosis (DKA). What are the key physiological changes in DKA, and how does the body attempt to compensate for the resulting acidosis?

Answer:

Diabetic ketoacidosis (DKA) occurs when there is insufficient insulin to regulate glucose metabolism, causing the body to break down fats for energy, which produces ketones. These ketones are acidic, leading to metabolic acidosis.

• Pathophysiology of DKA:
  • When insulin is insufficient, fat breakdown releases free fatty acids, which are converted into ketone bodies (mainly acetoacetate and beta-hydroxybutyrate). These ketones lower the blood pH, resulting in metabolic acidosis.
  • To compensate for the acidosis, the body uses respiratory compensation through Kussmaul breathing (deep, rapid breathing) to expel CO₂ and increase blood pH.
  • The kidneys also try to compensate by excreting hydrogen ions and retaining bicarbonate, but this compensatory response is slow.
• ABG Findings:
  • Low pH (below 7.35) due to the accumulation of ketone bodies.
  • Low bicarbonate (HCO₃⁻) (typically less than 18 mEq/L), indicating metabolic acidosis.
  • Normal or low PaCO₂ (less than 35 mmHg) as a result of respiratory compensation (hyperventilation).
• Management:
  • Fluid resuscitation with saline and insulin therapy to reduce blood glucose and stop ketone production.
  • Electrolyte replacement (especially potassium) is necessary to correct imbalances.
  • Monitoring for complications such as cerebral edema, which can arise during treatment, especially in pediatric patients.

 

What is the significance of the anion gap in the interpretation of metabolic acidosis, and how can it help differentiate between different causes of acidosis?

Answer:

The anion gap (AG) is a calculated value that helps determine the underlying cause of metabolic acidosis. It is the difference between the major cations (Na⁺) and the major anions (Cl⁻ and HCO₃⁻) in the blood, typically calculated as:

Anion Gap=(Na+)−(Cl−+HCO₃−)\text{Anion Gap} = (\text{Na}^+) – (\text{Cl}^- + \text{HCO₃}^-)Anion Gap=(Na+)−(Cl−+HCO₃−)

• Normal Anion Gap: A normal AG is typically between 8-12 mEq/L. When metabolic acidosis occurs with a normal AG, it is often due to bicarbonate loss (e.g., diarrhea, renal tubular acidosis) or hyperchloremia (increased chloride).
• High Anion Gap: A high AG (greater than 12 mEq/L) indicates the presence of unmeasured anions, which are typically acidic. Common causes include:
  • Diabetic Ketoacidosis (DKA): Elevated levels of ketones.
  • Lactic Acidosis: Elevated levels of lactate.
  • Renal Failure: Accumulation of phosphate and sulfate.
  • Ingestion of toxins: Such as methanol, ethylene glycol, or salicylates.
• ABG Findings in High Anion Gap Metabolic Acidosis:
  • Low pH (below 7.35) indicating acidosis.
  • Low bicarbonate (HCO₃⁻).
  • Low PaCO₂, as a compensatory response to the acidosis.
• Management:
  • Identifying and treating the underlying cause is essential. For example, insulin therapy for DKA, lactate clearance for lactic acidosis, or dialysis for renal failure.

 

How does the body compensate for respiratory alkalosis, and what ABG findings would be expected in a patient with hyperventilation due to anxiety?

Answer:

Respiratory alkalosis occurs when hyperventilation leads to the excessive loss of carbon dioxide (CO₂). This results in an increase in blood pH, leading to alkalosis.

• Compensatory Mechanism:
  • The kidneys attempt to compensate for the alkalosis by excreting bicarbonate (HCO₃⁻) to lower the buffering capacity of the blood and return pH to normal. However, this compensation is slow and may take hours to days to fully respond.
• ABG Findings in Respiratory Alkalosis:
  • Elevated pH (above 7.45) due to CO₂ loss.
  • Low PaCO₂ (below 35 mmHg), indicating hyperventilation and the loss of CO₂.
  • Normal or low bicarbonate (HCO₃⁻), reflecting renal compensation that has not fully occurred in acute settings.
• Management:
  • Reassurance and techniques to control hyperventilation, such as slow, deep breathing exercises.
  • In chronic or severe cases, cognitive-behavioral therapy (CBT) for anxiety may be indicated.

 

How do renal compensatory mechanisms work in response to respiratory acidosis, and what ABG findings would you expect in a patient with chronic respiratory failure?

Answer:

In respiratory acidosis, the PaCO₂ is elevated due to hypoventilation, which leads to a decrease in pH, causing acidosis. The kidneys attempt to compensate for this respiratory imbalance by increasing the retention of bicarbonate (HCO₃⁻) and excreting hydrogen ions (H⁺).

• Pathophysiology:
  • In chronic respiratory failure, the body becomes accustomed to higher levels of CO₂, and the kidneys gradually compensate over time. This compensatory process can take hours to days.
  • The kidneys increase the production of new bicarbonate ions and release them into the bloodstream, increasing the buffering capacity to counteract the acidic environment.
  • Respiratory compensation for acute respiratory acidosis involves increased depth and rate of breathing (e.g., Kussmaul breathing), but in chronic conditions, this may not be sufficient without renal compensation.
• ABG Findings in Chronic Respiratory Acidosis:
  • Low pH (below 7.35), reflecting acidosis.
  • High PaCO₂ (greater than 45 mmHg), reflecting CO₂ retention.
  • Normal or elevated bicarbonate (HCO₃⁻) (greater than 28 mEq/L), indicating renal compensation.
• Management:
  • Long-term oxygen therapy may be needed for patients with chronic respiratory failure, and adjusting ventilatory support helps manage CO₂ retention.
  • In severe cases, mechanical ventilation may be necessary to assist with CO₂ elimination.

 

Discuss the causes, symptoms, and ABG findings of lactic acidosis. How does the body attempt to compensate for this condition?

Answer:

Lactic acidosis occurs when lactate accumulates in the bloodstream, often as a result of tissue hypoxia or conditions that impair normal metabolism (e.g., sepsis, shock, or certain toxins).

• Pathophysiology:
  • Anaerobic metabolism produces lactate as an alternative energy source when oxygen supply is insufficient. This leads to the accumulation of lactic acid, causing a decrease in blood pH (metabolic acidosis).
  • The body attempts to compensate by increasing ventilation to excrete more CO₂ and decrease the acid load. This compensatory mechanism is seen as hyperventilation (increased rate and depth of breathing).
• ABG Findings in Lactic Acidosis:
  • Low pH (below 7.35) due to the accumulation of lactic acid.
  • Low bicarbonate (HCO₃⁻) (typically less than 18 mEq/L), indicating metabolic acidosis.
  • Normal or low PaCO₂ (below 35 mmHg) due to respiratory compensation.
• Management:
  • Treating the underlying cause is crucial, such as improving tissue oxygenation (e.g., with fluids, oxygen therapy, or inotropic support for shock).
  • In severe cases, sodium bicarbonate may be administered to neutralize the acid, although this is controversial and should be used cautiously.
  • Dialysis may be considered in cases of severe or refractory lactic acidosis.

 

How does the presence of a mixed acid-base disorder affect ABG interpretation, and what ABG findings would you expect in a patient with both metabolic acidosis and respiratory alkalosis?

Answer:

A mixed acid-base disorder occurs when two or more primary acid-base disturbances are present simultaneously. In these cases, the compensatory mechanisms of the body may obscure or complicate the interpretation of ABG results.

• Example of Mixed Disorder – Metabolic Acidosis and Respiratory Alkalosis:
  • This can occur in conditions such as diabetic ketoacidosis (DKA) with concurrent hyperventilation due to metabolic acidosis or in patients with sepsis or shock (which can cause both metabolic acidosis and compensatory respiratory alkalosis).
• Pathophysiology:
  • Metabolic acidosis is characterized by an elevated H⁺ concentration and low bicarbonate (HCO₃⁻). The body compensates by hyperventilating, which leads to respiratory alkalosis (a decrease in PaCO₂).
  • In respiratory alkalosis, CO₂ is rapidly expelled through hyperventilation, leading to a rise in pH.
• ABG Findings in Mixed Metabolic Acidosis and Respiratory Alkalosis:
  • Low pH (below 7.35) due to metabolic acidosis.
  • Low bicarbonate (HCO₃⁻) (less than 18 mEq/L) due to metabolic acidosis.
  • Low PaCO₂ (less than 35 mmHg) due to respiratory compensation (hyperventilation).
• Management:
  • Addressing the underlying cause is essential. For example, treating DKA with insulin and fluid resuscitation, or managing sepsis with antibiotics and fluids.
  • Oxygen therapy and ventilatory support may also be necessary to help correct respiratory alkalosis.

 

How does compensation for metabolic alkalosis differ in patients with chronic kidney disease (CKD), and what ABG findings would you expect in such patients?

Answer:

In metabolic alkalosis, the body retains excess bicarbonate (HCO₃⁻), and the kidneys attempt to compensate by excreting bicarbonate and retaining hydrogen ions (H⁺). However, in patients with chronic kidney disease (CKD), the kidneys’ ability to excrete bicarbonate is impaired, which may hinder their ability to compensate effectively for metabolic alkalosis.

• Pathophysiology in CKD:
  • CKD impairs kidney function, reducing the ability to excrete excess bicarbonate and causing the kidneys to retain bicarbonate, which can worsen metabolic alkalosis.
  • Respiratory compensation for metabolic alkalosis in CKD may occur through hypoventilation, which helps retain CO₂, but the compensatory effect is often insufficient in severe alkalosis.
• ABG Findings in Metabolic Alkalosis in CKD:
  • Elevated pH (greater than 7.45), indicating alkalosis.
  • Elevated bicarbonate (HCO₃⁻) (greater than 28 mEq/L), as the kidneys are unable to excrete bicarbonate effectively.
  • Normal or slightly elevated PaCO₂ (greater than 45 mmHg), indicating compensatory hypoventilation.
• Management:
  • Treatment of the underlying cause of alkalosis is essential, such as managing diuretics, correcting electrolyte imbalances, and adjusting for renal function through dialysis if necessary.
  • Acetazolamide or potassium-sparing diuretics may be used to correct bicarbonate retention and help restore balance.

 

How would the ABG interpretation differ in a patient with mixed respiratory acidosis and metabolic acidosis, and what clinical scenarios might cause these conditions to occur together?

Answer:

A mixed respiratory acidosis and metabolic acidosis occurs when both respiratory failure (leading to CO₂ retention) and a metabolic disturbance (such as lactic acidosis or renal failure) occur simultaneously.

• Pathophysiology:
  • In respiratory acidosis, PaCO₂ increases due to inadequate ventilation, causing a drop in pH.
  • In metabolic acidosis, an underlying condition (such as renal failure, DKA, or lactic acidosis) leads to an accumulation of acid in the body, further lowering the pH.
• ABG Findings in Mixed Respiratory and Metabolic Acidosis:
  • Low pH (below 7.35), reflecting the acidosis.
  • High PaCO₂ (greater than 45 mmHg) due to respiratory failure.
  • Low bicarbonate (HCO₃⁻) (less than 18 mEq/L) due to metabolic acidosis.
• Clinical Scenarios:
  • Severe COPD with acute exacerbation leading to respiratory acidosis and lactic acidosis from shock.
  • Renal failure with metabolic acidosis and respiratory compromise leading to hypoventilation (e.g., in critical illness or severe respiratory muscle weakness).
• Management:
  • Treat the underlying causes: improving ventilation, managing CO₂ retention (e.g., through mechanical ventilation) and correcting metabolic acidosis (e.g., with fluids, electrolyte correction, or dialysis in renal failure).

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