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

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-alpha (TNF-alpha) in obese patients undergoing gynecological laparoscopic surgery. Sixty patients, body mass index (BMI) >= 30 kg/m(2), 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 (Delta P = V (T)/C (RS)), arterial blood oxygen partial pressure/fraction of inspiration oxygen (PaO2/FiO(2)) 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-alpha, were also measured. When compared to patients in the VCV group, patients in the PCIRV group had higher V (T), dynamic C-RS, and PaO2/FiO(2), and lower Delta P and PaCO2 at 20 and 60 min after the start of pneumoperitoneum (p < 0.05). Patients in the PCIRV group had lower SP-A and TNF-alpha levels at 24 and 48 h 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-alpha. These effects demonstrate improved lung protection provided by PCIRV in this patient population.