Validity of arterialized earlobe blood gases at rest and exercise in normoxia and hypoxia

Abstract

The purpose of this study was to compare arterial and arterialized blood gases during normoxic and hypoxic exercise. In the same conditions, earlobe pulse oximetry O(2) saturation (Sp(O2)) was compared to arterial oxygen saturation (Sa(O2)). Ten men performed incremental cycle ergometer tests, in normoxia and hypoxia (FI(O2) = 0.127). Blood samples were drawn simultaneously from the radial artery and pre-warmed earlobe capillary blood of subjects at rest, submaximal and near maximal exercise. R(2) between the two samples were 0.99 for P(O2) and S(O2), 0.86 for P(CO2) and 0.97 between Sp(O2) and Sa(O2). Earlobe P(O2) mean was 4.4+/-3.6 mmHg lower than Pa(O2) in normoxia but in hypoxia only 1.1+/-2.2 mmHg low. The mean difference were low in normoxia between Sa(O2) and Sp(O2) and increased in hypoxia, were acceptable for P(CO2), S(O2), pH in all conditions. In conclusion, except for P(O2) in normoxia, pre-warmed earlobe capillary blood is a good substitute to arterial blood to allow measurement of blood gas values in normoxia and hypoxia at rest and exercise.