![]() Deoxygenated hemoglobin has a higher affinity for CO2 because it is a better proton acceptor than oxygenated hemoglobin. ![]() The Haldane Effect results from the fact that deoxygenated hemoglobin has a higher affinity (about 3.5 x) for CO2 than does oxyhemoglobin. Therefore, oxygen induces a rightward shift of the CO2 dissociation curve, which is known as the Haldane effect.ĭeoxygenated blood can carry increasing amounts of carbon dioxide, whereas oxygenated blood has a reduced carbon dioxide capacity. The Haldane effectĭeoxygenated hemoglobin (Hb) binds CO2 with greater affinity than oxygenated hemoglobin (HbO2). This increase in Va/Q mismatch occurs in both CO2 retainers and non-retainers, the difference is presumably one of degree. In COPD, patients optimize their gas exchange by hypoxic vasoconstriction leading to altered alveolar ventilation-perfusion (Va/Q) ratios.Įxcessive oxygen administration overcomes this, leading to increased blood flow to poorly ventilated alveoli, and thus increased Va/Q mismatch and increased physiological dead space. The real answer to the question involves two mechanisms:Ī V/Q mismatch occurs when part of the lung receives oxygen without blood flow or it receives blood flow without oxygen. ![]() Patients suffering from COPD exacerbation, regardless of whether they have CO2 retention, generally have a supra-normal respiratory drive (unless there is impending hypercapnic coma) This is not the case in patients with COPD. The traditional theory argues that oxygen administration to CO2 retainers causes loss of hypoxic drive, resulting in hypoventilation and type 2 respiratory failure. ![]() The answer to this isn't the traditional explanation. ![]()
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January 2023
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