Pressure-controlled inverse ratio ventilation improves gas exchange in obese children undergoing laparoscopic surgery: a randomized controlled study

Background: Obese children undergoing laparoscopic surgery frequently experience high end-tidal carbon dioxide partial pressure (PETCO2) and respiratory acidosis. This study aimed to investigate the effects of pressure controlled inverse ratio ventilation (IRV) with an inspiratory to expiratory ratio (I:E) of 1.5:1 on obese children undergoing laparoscopic surgery. Methods: Eighty children undergoing laparoscopic surgery were randomly assigned to either the IRV group (I:E=1.5:1) or the control group (I:E=1:1.5). The lungs were mechanically ventilated following tracheal intubation. The children underwent pressure-controlled ventilation with an I:E ratio of 1.5:1 or 1:1.5. Respiratory mechanics, hemodynamic values, and ventilation-related side effects were recorded. Results: Thirty minutes after establishing CO2 pneumoperitoneum, the IRV group exhibited significantly higher tidal volume (Vt) and arterial partial pressure of oxygen (PaO2) compared to the control group (97.6 +/- 6.6 vs. 93.2 +/- 8.0 ml, 283 +/- 54 vs. 247 +/- 40 mmHg, respectively) (P < 0.01). Furthermore, PaCO2 was significantly lower in the IRV group than in the control group (41.4 +/- 5.8 vs. 45.5 +/- 5.7 mmHg, P=0.002). The incidence of intra-operative hypercapnia was significantly decreased in the IRV group (25% vs. 42.5%, P=0.03). Conclusion: Pressure-controlled IRV can reduce the incidence of hypercapnia, increasing Vt, and thereby improving CO2 elimination in obese children undergoing laparoscopy. This ventilation technique significantly improves gas exchange in this patient population. (Registration number: ChiCTR2000035589).