Detection of disturbances in pulmonary gas exchanges during exercise from arterialized earlobe Po2

• Published in: Respiratory physiology & neurobiology Vol. 177; no. 1; pp. 30 - 35
• Main Authors: AGUILANIU, Bernard, MAITRE, Jocelyne, DIAB, Samia, PERRAULT, Helene, PERONNET, François
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 30-06-2011
• Subjects: Biological and medical sciences; Blood Gas Analysis; Blood Specimen Collection - methods; Carbon Dioxide - blood; Ear - blood supply; Exercise - physiology; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Middle Aged; Oxygen - analysis; Oxygen - blood; Predictive Value of Tests; Pulmonary Gas Exchange - physiology; Vertebrates: respiratory system; Physical exercise; Blood gas; Oxygen; Lung; Alveolar-capillary oxygen gradient; Respiratory system; Vertebrata; Mammalia; Exercise testing; pH; Gas exchange; Detection; Arterialized blood gas; Bayes theorem
• ISSN: 1569-9048; 1878-1519
• DOI: 10.1016/j.resp.2011.03.005

Blood sampling from the arterialized earlobe is widely used in clinical exercise testing but Fajac et al. (1998) (Eur. Respir. J. 11, 712-715) have shown that arterialized P(O2) Pc(CO2) is not a valid surrogate for Pa(O2). In the present study, in order to detect disturbances in pulmonary gas exchanges during clinical exercise testing from the alveolar-arterial gradient of P(O2) (P[Ai-a](O2)), a correction factor for Pc(O2) was validated from data on a large cohort (107 patients at one or two levels of exercise: 172 pairs of samples). Pulmonary gas exchanges and pH, P(O2), P(CO2), PA(iO2) and P(Ai-a)(O2) from arterial and arterialized blood were measured or computed. Arterial and arterialized pH and P(CO2) (and thus PA(iO2)) were similar but P(CO2) was lower than arterial P(O2) (Pa(O2)). However, when corrected for the systematic bias between Pa(O2) and Pc(O2), which increased with Pc(O2), Pc(O2) adequately detected disturbances in pulmonary gas exchanges with a very high sensibility and specificity (predictive values of a negative or positive test ∼95%).