Effects of pneumoperitoneal pressure and position changes on respiratory mechanics during laparoscopic colectomy.

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

Methods: 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°.

Results: 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/cmH(2)O 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/cmH(2)O. 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/cmH(2)O. Also in the airway resistance, the patient in the 20° head-down position with the PP of 10 mmHg showed 15.8 cmH(2)O/L/sec, while the patient in the 10° head-down position with the PP of 15 mmHg showed 16.2 cmH(2)O/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.

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