Hypoxaemia and the effect of aspirin in thalassaemia.

Blood gas analysis of arterial blood was performed in 34 patients with beta o-thalassaemia/haemoglobin E disease and homozygous beta o-thalassaemia. Among the 22 splenectomised patients 19 had PaO2 lower than the normal expected value, and 18 of these had PaO2 lower than 80 mmHg. Of the 12 non-splenectomised patients 5 had PaO2 lower than the expected normal value but only in one case it was lower than 80 mmHg. After aspirin or Persantin administration there was a definite rise in the PaO2 in 10 out of 12 patients. The hypoxaemia is believed to occur from increased platelet aggregation leading to pulmonary artery occlusion. The rise of the arterial PaO2 after aspirin administration indicates that the observed hypoxaemia is due to reversible platelet aggregation in the majority of cases.