The effect of pressure-controlled inverse ratio ventilation on lung protection in obese patients undergoing gynecological laparoscopic surgery.

Abstract

To examine the effects of pressure-controlled inverse ratio ventilation (PCIRV) and volume-control ventilation (VCV) on arterial oxygenation, pulmonary function, hemodynamics, levels of surfactant protein A (SP-A), and tumor necrosis factor-α (TNF-α) in obese patients undergoing gynecological laparoscopic surgery. Sixty patients, body mass index (BMI) ≥30kg/m2, scheduled for elective gynecological laparoscopic surgery were enrolled in the study. Patients were randomly allocated to receive either PCIRV with an inspiratory-expiratory (I:E) ratio of 1.5:1 (PCIRV group n=30) or VCV with an I:E ratio of 1:2 (VCV group n=30). Ventilation variables, viz. tidal volume (V T), dynamic respiratory-system compliance (C RS), driving pressure (ΔP=V T/C RS), arterial blood oxygen partial pressure/fraction of inspiration oxygen (PaO2/FiO2) and arterial blood carbon dioxide partial pressure (PaCO2), were measured. Hemodynamic variables, viz. mean arterial pressure (MAP), heart rate (HR), and serum levels of SP-A and TNF-α, were also measured. When compared to patients in the VCV group, patients in the PCIRV group had higher V T, dynamic CRS, and PaO2/FiO2, and lower ΔP and PaCO2 at 20 and 60min after the start of pneumoperitoneum (p<0.05). Patients in the PCIRV group had lower SP-A and TNF-α levels at 24 and 48h after surgery than those in the VCV group (p<0.05). In obese patients undergoing gynecological laparoscopic surgery, PCIRV can improve ventilation, promote gas exchange and oxygenation, and is associated with decreased levels of SP-A and TNF-α. These effects demonstrate improved lung protection provided by PCIRV in this patient population.