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

SPECIFIC AIM: 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.

METHODS: Sixty patients, body mass index (BMI) ≥30 kg/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.

RESULTS: 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 60 min after the start of pneumoperitoneum (p < 0.05). Patients in the PCIRV group had lower SP-A and TNF-α levels at 24 and 48 h after surgery than those in the VCV group (p < 0.05).

CONCLUSION: 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.