Effect of posture on the ventilatory response to CO2.
The effect of sitting and supine posture on breathing patterns and gas exchange during room air breathing and administration of 2 and 4% CO2 was studied in nine normal subjects using a noninvasive canopy system. During air breathing minute ventilation (VE) was 21% (P less than 0.005) higher in the sitting position. Tidal volume (VT) and mean inspiratory flow (VT/TI) were also greater in the sitting position. With the administration of 4% CO2, VE was 13.9 and 20.0 1/min in the supine and seated position, respectively. The relationship between VE and VT was the same in both cases. For any given level of VE, VT/TI was higher in the seated position. No difference in response to CO2 as measured by delta VE/delta PaCO2 and (delta VT/TI)/delta PaCO2 was observed. However, arterial PCO2 was lower both in the resting and stimulated states when sitting.
D000293:Adolescent; D000328:Adult; D001158:Arteries; D002245:Carbon Dioxide / Q000097:blood / Q000494:pharmacology*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D010313:Partial Pressure; D011187:Posture; D012119:Respiration / Q000187:drug effects*; D013990:Tidal Volume
D002245:Carbon Dioxide