This study was designed to assess the effects of pneumoperitoneal pressure (PP) and positional changes on the respiratory mechanics during laparoscopy assisted colectomy.

Peak inspiratory pressure, plateau pressure, lung compliance, and airway resistance were recorded in PP of 10 mmHg and 15 mmHg, with the position change in 5 steps: head-down at 20°, head-down at 10°, neutral position, head-up at 10° and head-up at 20°.

When the patient was placed head-down, the position change accentuated the effects of pneumoperitoneum on respiratory mechanics. However, when the patient was placed in a head-up position during pneumoperitoneum the results showed no pattern. In the 20° head-up position with the PP being 10 mmHg, the compliance increased from 30.6 to 32.6 ml/cmH₂O compared with neutral position (P = 0.002). However with the PP being 15 mmHg, the compliance had not changed compared with neutral position (P = 0.989). In 20° head-down position with the PP of 10 mmHg, the compliance was measured as 24.2 ml/cmH₂O. This was higher than that for patients in the 10° head-down position with a PP of 15 mmHg, which was recorded as 21.2 ml/cmH₂O. Also in the airway resistance, the patient in the 20° head-down position with the PP of 10 mmHg showed 15.8 cmH₂O/L/sec, while the patient in the 10° head-down position with the PP of 15 mmHg showed 16.2 cmH₂O/L/sec of airway resistance. These results were not statistically significant but still suggested that the head-down position accentuated the effects of pneumoperitoneum on respiratory mechanics.

Our results suggest that respiratory mechanics are affected by the patient position and the level of PP - the latter having greater effect.