It is common medical knowledge that there are two types of respiratory failure:
However, there are more types of respiratory failure. here are the details:
Classification:
Type 1 (Hypoxemic) - PO2< 50 mmHg on room air.
Usually seen in patients with acute pulmonary edema or acute lung injury. One of the classical examples is acute exacerbation of bronchial asthma. These disorders interfere with the lung's capacity to oxygenate blood as it flows through the pulmonary vasculature. CO2 level is normal in this type.
Type 2 (Hypercapnic/ Ventilatory) - PO2<50 mmHg and PCO2 > 50 mmHg.
This is usually seen in patients with an increased work of breathing due to airflow obstruction or decreased respiratory system compliance, with decreased respiratory muscle power due to neuromuscular disease, or with central respiratory failure and decreased respiratory drive.
Type 3 (Peri-operative). This is generally a subset of type 1 respiratory failure but is sometimes considered separately because it is common. Combined hypoxaemic and ventilatory failure in which features of type 1 and 2 are mixed, the defect including both alveolar hypoventilation and a disturbance of ventilation perfusion relationships within the lung. This produces a raised PCO2 and low PO2.
Type 4 (Shock) - secondary to cardiovascular instability.
Generally undergraduates are taught only the first two types for ease of understanding of the concept. But type 3 respiratory failure is quite common in clinical practice.
CLINICAL SUBJECTS 
CLINICAL SUBJECTS
