Respiratory Failure
Sodium bicarbonate is indicated in a patient with metabolic acidosis associated with respiratory failure
Respiratory failure
- Especially in status asthmaticus . Air trapping → hypoventilation → hypoxia and hypercapnia (respiratory acidosis). The patient compensates with ↑ respiratory rate and accessory-muscle use.
- Exam pearl: a normal or rising PaCO₂ in an acute attack is ominous — the patient is tiring.
Read this in Bronchial Asthma: Pathophysiology, Diagnosis and GINA Stepwise Management
What our notes say
- Sodium bicarbonate is indicated in a patient with metabolic acidosis associated with respiratory failure (Paediatrics Year 6 MBChB end of semester CAT: clinical case MCQs, 29 of 30 quest)
- Ascending symmetric weakness, absent reflexes, autonomic instability and respiratory failure after an infection is Guillain-Barre syndrome. (Paediatrics end of fourth year main exam: 1 July 2019, Paper One, 99 of 100 MCQs)
- A PaCO₂ of 40 mmHg is abnormal in pregnancy and means respiratory failure is near. (Physiological changes in pregnancy)
- > SSP is more dangerous than PSP — poor lung reserve means even a small one may cause respiratory failure. (Pneumothorax: Classification, Clinical Features and Emergency Management)
- • To deliver oxygen to the lungs when a person is unable to breathe normally – the loss of normal lung function is called respiratory failure (see below) (Examination of Respiratory system — Past Paper Questions & Answers)
- Parapneumonic effusion and empyema, lung abscess, sepsis and septic shock, respiratory failure and ARDS, pleurisy, pericarditis, lobar collapse, metastatic infection (meningitis, endocarditis, arthritis), bronchiectasis (long term). (Pneumonia)
Study material on Respiratory Failure
Practice questions on Respiratory Failure
A 70-year-old man with severe COPD has increasing drowsiness. ABG shows pH 7.28, PaO2 55 mmHg, PaCO2 72 mmHg, and HCO3 32 mEq/L. What is the most likely type of respiratory failure?
- Type I (hypoxemic)
- Type II (hypercapnic)
- Type III (perfusion defect)
- Type IV (pump failure)
Answer: B. This ABG demonstrates respiratory acidosis (pH 7.28) with significant hypercapnia (PaCO2 72 mmHg) and hypoxemia (PaO2 55 mmHg). This is characteristic of Type II respiratory failure, often seen in severe COPD due to alveolar hypoventilation.
A 70-year-old man with severe COPD has increasing drowsiness. ABG shows pH 7.28, PaO2 55 mmHg, PaCO2 72 mmHg, and HCO3 32 mEq/L. Most likely type of respiratory failure?
- Type 2 respiratory failure (hypercapnic)
- Type 1 respiratory failure (hypoxemic)
- Combined type 1 and 2 respiratory failure
- Cardiogenic pulmonary edema
Answer: A. The ABG shows significant hypoxemia (PaO2 55 mmHg) and hypercapnia (PaCO2 72 mmHg), with a compensated metabolic alkalosis (HCO3 32 mEq/L, indicating chronic retention of CO2). This pattern, especially with drowsiness, signifies Type 2 (hypercapnic) respiratory failure, often superimposed on underlying hypoxemia in severe COPD.
A 70-year-old man with severe COPD has increasing drowsiness. ABG shows pH 7.28, PaO2 55 mmHg, PaCO2 72 mmHg, and HCO3 32 mEq/L. Most likely type of respiratory failure?
- Type 1 (hypoxemic)
- Type 2 (hypercapnic)
- Type 3 (peroperative)
- Type 4 (ischemic)
Answer: B. The ABG demonstrates significant hypoxemia (PaO2 55 mmHg) and hypercapnia (PaCO2 72 mmHg) with a resultant respiratory acidosis (pH 7.28). This combination, especially with the elevated PaCO2 and decreased pH, indicates Type 2 (hypercapnic) respiratory failure, common in severe COPD exacerbations.
A 70-year-old man with severe COPD has increasing drowsiness. ABG shows pH 7.28, PaO2 55 mmHg, PaCO2 72 mmHg, and HCO3 32 mEq/L. What is the most likely type of respiratory failure?
- Type I (Hypoxemic)
- Type II (Hypercapnic)
- Type III (Perfusion defect)
- Type IV (Pump failure)
Answer: B. This ABG shows both hypoxemia (PaO2 55 mmHg) and hypercapnia (PaCO2 72 mmHg) with a compensated metabolic alkalosis (HCO3 32 mEq/L). While hypercapnia is present, the severe hypoxemia is the most life-threatening abnormality driving the clinical picture and leading to drowsiness. This combination defines Type II respiratory failure, which can also have hypoxemic components in severe cases of COPD.
A 70-year-old man with severe COPD has increasing drowsiness. ABG shows pH 7.28, PaO2 55 mmHg, PaCO2 72 mmHg, and HCO3 32 mEq/L. Most likely type of respiratory failure?
- Type 2 (hypercapnic)
- Type 1 (hypoxemic)
- Mixed Type 1 and Type 2
- Cardiogenic shock
Answer: A. This ABG demonstrates severe hypercapnia (PaCO2 72 mmHg) with a corresponding respiratory acidosis (pH 7.28). While hypoxemia is also present (PaO2 55 mmHg), the primary driver of the patient's drowsiness and acidosis is the elevated CO2, indicative of Type 2 respiratory failure.
A 70-year-old man with severe COPD has increasing drowsiness. ABG shows pH 7.28, PaO2 55 mmHg, PaCO2 72 mmHg, and HCO3 32 mEq/L. Most likely type of respiratory failure?
- Type I (hypoxemic)
- Type II (hypercapnic)
- Type III (perfusion defect)
- Type IV (shock)
Answer: B. The ABG shows both hypoxemia (PaO2 55 mmHg) and hypercapnia (PaCO2 72 mmHg) with respiratory acidosis (pH 7.28). However, the defining feature for Type II respiratory failure is the elevated PaCO2 leading to respiratory acidosis. While hypoxemia is present, it is a consequence of the impaired ventilation. The presence of significant hypercapnia and acidosis indicates Type II (hypercapnic) respiratory failure. The ele