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).
CONCLUSIONS: 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).

OBJECTIVE: To investigate the effect of inverse ratio ventilation (IRV) combined with positive end-expiratory pressure (PEEP) in infants undergoing thoracoscopic surgery with single lung ventilation (OLV) for lung cystadenomas.
METHODS: A total of 66 infants undergoing thoracoscopic surgery with OLV for lung cystadenomas in our hospital from February, 2018 to February, 2019 were randomized into conventional ventilation groups (group N, n=33) and inverse ventilation group (group R, n=33). Hemodynamics and respiratory parameters of the infants were recorded and arterial blood gas analysis was performed at 15 min after two lung ventilation (TLV) (T1), OLV30 min (T2), OLV60 min (T3), and 15 min after recovery of TLV (T4). Bronchoalveolar lavage fluid was collected before and after surgery to detect the expression level of advanced glycation end product receptor (RAGE).
RESULTS: Sixty-three infants were finally included in this study. At T2 and T3, Cdyn, PaO2 and OI in group R were significantly higher (P < 0.05) and Ppeak, PaCO2 and PA-aO2 were significantly lower than those in group N (P < 0.05). There was no significant difference in HR or MAP between the two groups at T2 and T3 (P > 0.05). The level of RAGE significantly increased after the surgery in both groups (P < 0.05), and was significantly lower in R group than in N group (P < 0.05).
CONCLUSIONS: In infants undergoing thoracoscopic surgery with OLV for pulmonary cystadenoma, appropriate IRV combined with PEEP does not affect hemodynamic stability and can increases pulmonary compliance, reduce the peak pressure, and improve oxygenation to provide pulmonary protection.

UNASSIGNED: 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).
CONCLUSIONS: 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.

BACKGROUND: High peak airway pressure (Ppeak) and high end-tidal carbon dioxide tension (PETCO2) are the common problems encountered in the obese patients undergoing gynecological laparoscopy with conventional volume-controlled ventilation. This study was designed to investigate whether volume-controlled inverse ratio ventilation (IRV) with inspiratory to expiratory (I:E) ratio of 2:1 could reduce Ppeak or the plateau pressure (Pplat), improve oxygenation, and alleviate lung injury in patients with normal lungs.
METHODS: Sixty obese patients undergoing gynecological laparoscopy were enrolled in this study. After tracheal intubation, the patients were randomly divided into the IRV group (n = 30) and control group (n = 30). They were ventilated with an actual tidal volume of 8 mL/kg, respiratory rate of 12 breaths/min, zero positive end-expiratory pressure and I:E of 1:2 or 2:1. Arterial blood samples, hemodynamic parameters, and respiratory mechanics were recorded before and during pneumoperitoneum. The concentrations of tumor necrosis factor-α, and interleukins 6 and 8 in bronchoalveolar lavage fluid were measured immediately before and 60 minutes after onset of CO2 pneumoperitoneum.
RESULTS: IRV significantly increased arterial partial pressure of oxygen, mean airway pressure, and dynamic compliance of respiratory system with concomitant significant decreases in Ppeak and Pplat compared to conventional ventilation with I:E of 1:2 (p < 0.05). Additionally, the levels of tumor necrosis factor-α, and interleukins 6 and 8 were significantly lower than those in control group (p < 0.05).
CONCLUSIONS: Volume-controlled IRV not only reduces Ppeak, Pplat, and the release of inflammatory cytokines, but also increases mean airway pressure, and improves oxygenation and dynamic compliance of respiratory system in obese patients undergoing gynecologic laparoscopy without adverse respiratory and hemodynamic effects. It is superior to conventional ratio ventilation in terms of oxygenation, respiratory mechanics and inflammatory cytokine in obese patients undergoing gynecologic laparoscopy.