[Application of bedside monitoring with arterized capillary blood, transcutaneous and end tidal carbon dioxide during mechanical ventilation].

Arterial blood, arterialized capillary blood, transcutaneous, end tidal carbon dioxide pressure (PaCO2, PcCO2, PtcCO2, PetCO2) and physiological respiratory deadspace to tidal volume ratio (VD/VT) were observed in 12 patients with chronic obstructive pulmonary disease (group A), 17 postoperative patients of cardiac surgery (group B), and 16 healthy subjects (group C) under three mechanical ventilatory patterns. PcCO2, PtcCO2 and PetCO2 were found to correlate well with PaCO2 (r = 0.99, 0.97 and 0.88 respectively); P(a-et) CO2 correlated with age (year) in group B and C (r = 0.77 and 0.76), and all P(a-et) CO2 measurements of each of three groups highly correlated with VD/VT (r = 0.96 0.91 and 0.87 for group A,B,C respectively). The results suggested that the trend of PaCO2 variation can be deduced from PcCO2, PtcCO2 and PetCO2 with fair accuracy under various ventilatory patterns in subjects with stable circulatory function, and P(a-et) CO2 is a simple quantitative index for evaluating physiological deadspace.