The effects of neuromuscular block on peak airway pressure and abdominal elastance during pneumoperitoneum

Administration of muscle relaxants is considered as necessary to prevent high intraabdominal and peak inspiratory pressures induced by pneumoperitoneum during laparoscopy. In the present study, we hypothesized that neuromuscular block does not alter pulmonary or abdominal elastic properties in pigs receiving general anesthesia. To test this hypothesis, changes in peak airway pressure and abdominal elastance during intraabdominal CO(2), insufflation from 0 to 15 mm Hg were recorded in anesthetized pigs, with or without muscle relaxants. A 100% increase in peak inspiratory airway pressure was obtained. This was unaffected by neuromuscular block induced by atracurium (13.2 +/- 5.0 mm Hg vs 25.0 +/- 4.8 mm Hg for the control group and 12.6 +/- 5.0 mm Hg vs 23.5 +/- 6.2 mm Hg for the paralyzed group). Abdominal pressure/volume relationships were independent of muscle relaxant administration (calculated elastance was 3.98 +/- 1.56 mm Hg/L without muscle relaxant vs 3.86 +/- 1.37 mmHg/L in the atracurium group). We conclude that high peak inspiratory airway pressures and intraabdominal pressures during laparoscopy are not affected by neuromuscular block. These findings also question the necessity of muscle relaxants in clinical anesthetic practice during laparoscopic surgery.