A method for monitoring arterial blood gas and acid/base state during prolonged environmental studies

The use of ear lobe arterialized capillary blood for monitoring blood gas tension and acid-base state is described. The method was validated against simultaneously taken arterial blood samples and separately against nasal end-tidal (ET) PCO2 and found to be an effective alternative to arterial puncture. Incidental observations showed that breathing through a mouthpiece caused the subjects to hypoventilate, as did the act of blood sampling with most subjects. Nasal ET gas monitoring was found to have less effect on a subject's breathing pattern and was used as the standard against which the effects of the other techniques were judged.