Respiratory patterns after cholecystectomy. Effects of posture and CO2 stimulation.

A marked reduction in the ratio of abdominal to rib cage motion has been observed after upper abdominal surgery. This study seeks to determine the effects on respiratory pattern of stimulation with CO2 and a change in posture from supine to semirecumbent posture (hips flexed, head of bed elevated at 30 degrees to the horizontal) in patients having undergone cholecystectomy. Canopy spirometry and respiratory inductive plethysmography were used to measure minute ventilation, tidal volume, and rib cage and abdominal motion in 14 otherwise healthy women, prior to elective cholecystectomy and on the first and third postoperative days. Preoperatively, the relative contribution of the chest wall compartment to tidal volume (Vc/VT) was increased both by moving from the supine to the semirecumbent posture and by stimulation with 4 percent inhaled CO2. On the first postoperative day, there was a reduction in abdominal motion. In contrast to what happened in the preoperative period, there was no change in the relative contribution of the rib cage and abdomen when the patients moved from the supine to semirecumbent position. With CO2 stimulation, there was a further increase in the already increased absolute tidal volume of the chest. On the third postoperative day, there was an increase in abdominal motion in the supine and sitting position and during 4 percent CO2 stimulation. These results demonstrate that the response to a change in posture and to 4 percent CO2 stimulation are markedly altered in the postoperative period by the reduction in abdominal motion.