Changes in pulmonary mechanics during laparoscopic gastroplasty in morbidly obese patients

TLDR

Obesity increases respiratory risk after abdominal surgery, but laparoscopic techniques appear to reduce respiratory morbidity and accelerate recovery of normal function. The study aimed to characterize intraoperative respiratory mechanics and tolerance to abdominal insufflation in morbidly obese patients. Respiratory mechanics and arterial blood gases were measured in 15 morbidly obese patients (BMI ≈ 45) undergoing laparoscopic gastroplasty under general anesthesia with controlled ventilation, using side‑stream spirometry. Insufflation to 2.26 kPa lowered compliance by 31 %, raised peak and plateau pressures by 17 % and 32 % respectively, induced hypercapnia without affecting O₂ saturation, and all parameters returned to baseline after deflation, indicating that laparoscopic surgery is safe and better tolerated than in non‑obese patients.

Abstract

Background: Obesity is an important respiratory risk factor after abdominal surgery. Laparoscopic surgical techniques seem beneficial in obese patients in terms of respiratory morbidity, with a faster return to normal respiratory function. However, there is little information about intraoperative respiratory mechanics and about patient tolerance to abdominal insufflation in the morbidly obese. Methods: We studied respiratory mechanics and arterial blood gases in 15 morbidly obese patients (mean BMI=45) undergoing laparoscopic gastroplasty under general anaesthesia and controlled ventilation. Respiratory mechanics were analysed using side‐stream spirometry. Results: When compared to preinsufflation values, servocon‐trolled abdominal insufflation to 2.26 kPa caused a significant decrease in respiratory system compliance (31%), a significant increase in peak (17%) and plateau (32%) airway pressures at constant tidal volume with a significant hypercapnia but no change in arterial O 2 saturation. Respiratory system compliance and pulmonary insufflation pressures returned to baseline values after abdominal deflation. Conclusion: These alterations in pulmonary mechanics are less than those observed with comparable degrees of abdominal inflation in non‐obese patients, and were well tolerated. From the point of view of intraoperative respiratory mechanics, laparoscopic surgery is safe in morbidly obese patients.