Effect of inverse ratio ventilation on hemodynamics and respiratory mechanics in obese patients undergoing laparoscopic sleeve gastrectomy

Background
Obesity has become a global epidemic problem affecting every system and is associated with many consequences including coronary artery disease, hypertension, diabetes mellitus, dyslipidemia, obstructive sleep apnea, and socioeconomic and psychosocial impairment. Laparoscopic sleeve gastrectomy is one of the best and most commonly done operations for weight loss. Elevated peak airway pressure and hypoxemia are common problems that anesthesiologists face during laparoscopic surgeries with conventional volume-controlled ventilation. This study aimed at the use of the prolonged I:E ratio as an alternative strategy to improve gas exchange and the respiratory mechanics of obese patients undergoing laparoscopic sleeve gastrectomy.
Results
The study was a prospective randomized controlled trial and was performed between April 2019 and March 2020. After the approval of the departmental ethical committee and the informed written consent had been taken from the patients, fifty-two obese patients undergoing laparoscopic sleeve gastrectomy were enrolled in this study. After endotracheal intubation, the patients were randomly divided into the IRV group (=26) and the VCV group (=26). Respiratory parameters were adjusted as tidal volume (Vt) 8mL/kg ideal body weight, respiratory rate 12 breaths/min, positive-end expiratory pressure (PEEP) 0, fractional inspired oxygen (FiO) 0.6, and I:E ratio 1:2 for the VCV group and 2:1 for the IRV group; hemodynamics and respiratory mechanics were monitored and recorded after intubation (0 min), before pneumoperitoneum (10 mins), and after pneumoperitoneum (20 mins), 30, 40, 50, and 60 mins. IRV significantly improves the respiratory mechanics during pneumoperitoneum in the form of decreasing the peak pressure (Ppeak) and plateau pressure (Pplat) and improving the dynamic compliance, but the mean pressure (Pmean) was increased; it also increased the partial pressure of oxygen (arterial PO) significantly. No statistical significance was found regarding the demographic data or the hemodynamics.
Conclusion
IRV is superior to conventional VCV in morbidly obese patients undergoing laparoscopic sleeve gastrectomy as it improves respiratory mechanics and oxygenation.