Type 1 respiratory failure is characterized by:
Ans: a (Low PaO2 and normal PCO2) Ref: Harrison, 16th ed, p. 1583,1584; 17th ed, p. 1675Type 1 respiratory failure is characterized by low PaO2 with normal or decreased PCO2Type 1 respiratory failureType II respiratory failureIt is due to the failure of oxygenation, characterized by low PaO2 with normal or decreased PCO2.PaO2 low- (< 60 mm Hg)Pa CO2 - normal or low (</= 49 mmHg)P(A-a)O, is increasedThe alveolar arterial oxygen gradient is increased because of the defective oxygenation in the alveoli.This results in decreased PaC02 even though the partial pressure of oxygen in the alveoli is normal.So the gradient P(A-a)O2 increases.It represents a defect in ventilation ie, hypoventilation characterized by decreased PaO2 with increased PaCO2.PaO2 < 60 mm HgPaCO2 >49 mmHgP(A-a)O2 is normalCauses of Type 1 respiratory failure:Causes of Type II respiratory failureConditions which affect oxygenation.Parenchymal diseases (V-Q mismatch).Diseases of vasculature/ shuntsEgPneumoniaARDSEmphysemaRight to left shuntsObstructive lung disease, e.g.: COPDDecreased central respiratory drive, e.g.: brain injury, meningitisRespiratory muscle weaknessEg;Peripheral nervous system disorders like:Myasthenia,Musculoskeletal disorders like polymyositisRib cage disorders, e.g.: kyphoscoliosis
Low PaO2 normal PCO2
|PaO2 and | PCO2
Normal PaO2, | PCO2
|PaO2, |PCO2
Respiratory