Maintaining oxygenation during neonatal open repair of esophageal atresia/tracheoesophageal fistula is difficult. Inverse ratio ventilation can be used during one lung ventilation to improve the oxygenation and lung mechanics.
The aim of this study was to describe the impact of two different ventilatory strategies (inverse ratio ventilation vs. conventional ratio ventilation) during one lung ventilation in neonatal open repair of esophageal atresia/tracheoesophageal fistula on the incidence of oxygen desaturation episodes.
We enrolled 40 term neonates undergoing open right thoracotomy for esophageal atresia/tracheoesophageal fistula repair and randomly assigned into two groups based on inspiratory to expiratory ratio of mechanical ventilation parameters (2:1 in inverse ratio ventilation \"IRV\" and 1:2 in conventional ratio ventilation \"CRV\"). The incidence of desaturation episodes that required stopping the procedure and reinflation of the lung were recorded as the primary outcome while hemodynamic parameters, incidence of complications, and length of surgical procedure were recorded as the secondary outcomes.
There was a trend toward a reduction in the incidence of severe desaturations (requiring stopping of surgery) with the use of inverse ratio ventilation (15% in IRV vs. 35% in CRV, RR [95% CI] 0.429 [0.129-1.426]). Incidence of all desaturations (including those requiring only an increase in ventilatory support or inspired oxygen saturation) was also reduced (40% in IRV vs. 75% in CRV, RR [95% CI] 0.533 [0.295-0.965]). This in turn affected the length of surgical procedure being significantly shorter in inverse ratio ventilation group (mean difference -16.3, 95% CI -31.64 to -0.958). The intraoperative fraction of inspired oxygen required to maintain adequate oxygen saturation was significantly lower in the inverse ratio ventilation group than in the conventional ratio ventilation group (mean difference -0.22, 95% CI -0.33 to -0.098), with no significant difference in hemodynamic stability or complications apart from higher blood loss in inverse ratio group.
There may be a role for inverse ratio ventilation with appropriate positive end-expiratory pressure to reduce the incidence of hypoxemia during open repair of esophageal atresia/tracheoesophageal fistula in neonates, further studies are required to establish the safety and efficacy of this technique.

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).

UNASSIGNED: Induction of general anaesthesia is associated with development of atelectasis in the lungs, which may further lead to postoperative pulmonary complications. Inverse ratio ventilation (IRV) has shown to improve oxygenation and minimise further lung injury in patients with acute respiratory distress syndrome. We evaluated the safety and effectiveness of IRV on intraoperative respiratory mechanics and postoperative pulmonary function tests (PFTs).
UNASSIGNED: In a prospective, controlled study, 128 consecutive patients with normal preoperative PFTs who underwent elective laparoscopic cholecystectomy were randomised into IRV and conventional ventilation groups. Initially, all patients were ventilated with settings of tidal volume 8 mL/kg, respiratory rate 12/min, inspiratory/expiratory ratio (I: E) = 1:2, positive end expiratory pressure = 0. Once the pneumoperitoneum was created, the conventional group patients were continued to be ventilated with same settings. However, in the IRV group, I: E ratio was changed to 2:1. Peak pressure (Ppeak), Plateau pressure (Pplat) and lung compliance were measured. Haemodynamic parameters and arterial blood gas values were also measured. PFTs were repeated in postoperative period. Statistical tool included Chi-square test.
UNASSIGNED: There was no significant difference in PFTs in patients who underwent IRV as compared to conventional ventilation [forced vital capacity (FVC) 2.52 ± 0.13 versus 2.63 ± 0.16, P = 0.28]. The Ppeak (cmH2O) and Pplat (cmH2O) were statistically lower in IRV patients [Ppeak 21.4 ± 3.4 versus 22.4 ± 4.2, P = 0.003] [Pplat 18.7 ± 2.4 versus 19.9.4 ± 3.2, P = 0.008]. There was no significant difference in lung compliance and oxygenation intraoperatively.
UNASSIGNED: Intraoperative IRV led to reduced airway pressures; however, it did not prevent deterioration of PFTs in postoperative period.

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.

暂无摘要。

OBJECTIVE: Low tidal volume ventilation improves the outcomes of acute respiratory distress syndrome (ARDS). However, no studies have investigated the use of a rescue therapy involving mechanical ventilation when low tidal volume ventilation cannot maintain homeostasis. Inverse ratio ventilation (IRV) is one candidate for such rescue therapy, but the roles and effects of IRV as a rescue therapy remain unknown.
METHODS: We undertook a retrospective review of the medical records of patients with ARDS who received IRV in our hospital from January 2007 to May 2014. Gas exchange, ventilation, and outcome data were collected and analyzed.
RESULTS: Pressure-controlled IRV was used for 13 patients during the study period. Volume-controlled IRV was not used. IRV was initiated on 4.4 ventilation days when gas exchange could not be maintained. IRV significantly improved the PaO2/FiO2 from 76 ± 27 to 208 ± 91 mmHg without circulatory impairment. The mean duration of IRV was 10.5 days, and all survivors were weaned from mechanical ventilation and discharged. The 90-day mortality rate was 38.5 %. Univariate analysis showed that the duration of IRV was associated with the 90-day mortality rate. No patients were diagnosed with pneumothorax.
CONCLUSIONS: Pressure-controlled IRV provided acceptable gas exchange without apparent complications and served as a successful bridge to conventional treatment when used as a rescue therapy for moderate to severe ARDS.

OBJECTIVE: To observe the 28 and 90 days mortality associated with prone position and assist control-pressure control (with inverse ratio) ventilation (ACPC-IRV).
METHODS: All patients who were admitted to our medical Intensive Care Unit (ICU) who are positive for H1N1 viral infection with severe acute respiratory distress syndrome (ARDS) and requiring invasive mechanical ventilation in prone position were included in our prospective observational study. Six patients who are positive for H1N1 required invasive ventilation in prone position. These patients were planned to ventilate in prone for 16 h and in supine for 8 h daily until P/F ratio >150 with FiO2 of 0.6 or less and positive end-expiratory pressure <10 cm of H2 O.
RESULTS: At admission, among these six patients the mean tidal volume generated was about 376.6 ml which was in the range of 6-8 ml/kg predicted body weight. The mean lung injury score was 3.79, mean PaO2 /FiO2 ratio was 52.66 and mean oxygenation index was 29.83. The mean duration of ventilation was 9.4 days (225.6 h). The ICU length of stay was 11.16 days. There was no mortality at 28 and 90 days.
CONCLUSIONS: Early prone combined with ACPC-IRV in H1N1 patients having severe ARDS can be used as a rescue therapy and it should be confirmed by large observational studies.

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.

BACKGROUND: It is well documented that pressure-controlled ventilation (PCV) improves oxygenation and ventilation compared to volume-controlled ventilation and reduces peak airway pressure in gynecological laparoscopy. PCV with moderately inversed inspiratory-expiratory (I: E) ratio can successfully recruit collapsed alveoli and has been proved to be beneficial in intensive care. We tested the hypothesis that altering the I: E ratio to 1.5:1 in PCV improves ventilation during gynecological laparoscopy using laryngeal mask airway (LMA).
OBJECTIVE: To study pressure-controlled inverse ratio ventilation (PCIRV) with I: E ratio 1.5:1 as against PCV with I: E ratio 1:2 in gynecological laparoscopy with LMA using noninvasive parameters.
METHODS: Intraoperative hemodynamics and side-stream spirometry recordings were noted in 20 consecutive patients undergoing major gynecological laparoscopy with LMA. Flexible LMA or LMA supreme were used depending on normal body mass index (BMI) or high BMI, respectively.
RESULTS: REVERSING THE I: E ratio to 1.5:1 increased the tidal volume, mean airway pressures, and dynamic lung compliance significantly, all indicating better oxygenation at comparable peak airway pressures as against PCV with I: E ratio 1:2. There was no change in the end-tidal carbon dioxide. There was no auto-positive end expiratory pressure (PEEP) or change in the hemodynamics.
CONCLUSIONS: REVERSAL OF I: E ratio with PCV can be beneficially used with LMA in laparoscopy.