Cardiopulmonary Effects of Laparoscopic Surgery, Revisited

Abstract

In a well-written article, Sharma et al (September 1996)1Sharma K.C. Brandstetter R.D. Brensilver J.M. et al.Cardiopulmonary physiology and pathophysiology as a consequence of laparoscop$$ surgery.Chest. 1996; 110: 810-815Abstract Full Text Full Text PDF PubMed Scopus (146) Google Scholar reviewed the cardiopulmonary effects of laparoscopy. However, there are two additional studies of respiratory mechanics of interest to your readers. One study measured airway flow and airway and esophageal pressures of anesthetized/paralyzed, tracheally intubated patients during mechanical ventilation.2Fahy B.G. Barnas G.M. Flowers J.L. et al.The effects of increased abdominal pressure on lung and chest wall mechanics during laparoscopic surgery.Anesth Analg. 1995; 81: 744-750PubMed Google Scholar Measurements were made in the appropriate supine positions for gastrointestinal laparoscopy, using 15° Trendelenburg and 10° reverse Trendelenburg positions at pneumoperitoneal pressures of 0, 15, and 25 mm Hg. From these measurements, discrete Fourier transformation was used to calculate lung and chest wall elastances and resistances. All measurements in the Trendelenburg position increased with 15 mm Hg pneumoperitoneum, and both lung and chest wall elastances increased further with pneumoperitoneum at 25 mm Hg (p<0.05). Although both lung and chest wall elastances and resistances increased in the reverse Trendelenburg position at 15 mm Hg pneumoperitoneal pressure, the increases in lung elastance and resistance were less compared to measurements in the Trendelenburg position (p<0.05). The increases in lung elastance and resistance at 15 mm Hg were positively correlated to body mass index or body weight; chest wall elastance and resistance increases were negatively correlated to the same factors (p<0.05). Intraoperatively, lung and chest wall mechanical impedances increase with increasing pneumoperitoneal pressures and are dependent on body configuration and position. These changes should be considered in patients with pulmonary disease or obesity because this increase in impedance may be critical. To evaluate whether these large increases in lung and chest wall elastances and lung resistance were reversed or remained following release of pneumoperitoneum and completion of laparoscopy, another study3Fahy B.G. Barnas G.M. Nagle S.E. et al.Changes in lung and chest wall properties with abdominal insufflation of carbon dioxide are immediately reversible.Anesth Analg. 1996; 82: 501-505PubMed Google Scholar compared respiratory mechanics immediately before the pneumoperitoneum and following deflation. Lung elastances and resistances after release of the pneumoperitoneum were not changed from baseline (p>0.05), although total respiratory elastance remained slightly increased compared with baseline (p<0.05). Thus, the reported compromise of respiratory function indicated by postoperative pulmonary function tests after laparoscopy does not appear to be due to changes in lung or chest wall passive mechanical properties. As more procedures are performed in patients with cardiopulmonary disease, the period of pneumoperitoneum with its concomitant respiratory mechanical changes will achieve greater importance.