Journal of Applied Physiology, Vol 64, Issue 5 1858-1863, Copyright © 1988 by American Physiological Society
Time-dependent variations of transcutaneous PCO2 level in normal subjects
D. Pilsbury and G. Hibbert
Oxford University, Department of Psychiatry, Warneford Hospital, United Kingdom.
Transcutaneous PCO2 (PtcCO2), which is linearly related to arterial PCO2,
was continuously recorded in healthy, adult, normal volunteers for 8-h
periods. Recording this variable with the apparatus employed permits
measurement of changes in the level of ventilation while subjects are
freely ambulant and unencumbered by invasive and flow-resistive respiratory
apparatus. The time series obtained exhibited marked periodicities. The
frequencies and amplitudes varied between subjects. Peak-to-peak variation
was 10-20% of mean values. There was no apparent association between
fluctuations in PCO2 and activity other than formal exercise. Visual
inspection of the time series and preliminary statistical analysis of
digitally converted data suggested that the time-dependent changes of
PtcCO2 were normally distributed. However, more rigorous statistical
examination revealed that in no case was PtcCO2 actually normally
distributed.
