Pressure-controlled inverse ratio ventilation using laryngeal mask airway in gynecological laparoscopy

Inverse ratio ventilation versus conventional ratio ventilation during one lung ventilation in neonatal open repair of esophageal atresia/tracheoesophageal fistula: A randomized clinical trial

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Effect of inverse ratio ventilation on hemodynamics and respiratory mechanics in obese patients undergoing laparoscopic sleeve gastrectomy

Background

Obesity has become a global epidemic problem affecting every system and is associated with many consequences including coronary artery disease, hypertension, diabetes mellitus, dyslipidemia, obstructive sleep apnea, and socioeconomic and psychosocial impairment. Laparoscopic sleeve gastrectomy is one of the best and most commonly done operations for weight loss. Elevated peak airway pressure and hypoxemia are common problems that anesthesiologists face during laparoscopic surgeries with conventional volume-controlled ventilation. This study aimed at the use of the prolonged I:E ratio as an alternative strategy to improve gas exchange and the respiratory mechanics of obese patients undergoing laparoscopic sleeve gastrectomy.

Results

The study was a prospective randomized controlled trial and was performed between April 2019 and March 2020. After the approval of the departmental ethical committee and the informed written consent had been taken from the patients, fifty-two obese patients undergoing laparoscopic sleeve gastrectomy were enrolled in this study. After endotracheal intubation, the patients were randomly divided into the IRV group (n=26) and the VCV group (n=26). Respiratory parameters were adjusted as tidal volume (Vt) 8mL/kg ideal body weight, respiratory rate 12 breaths/min, positive-end expiratory pressure (PEEP) 0, fractional inspired oxygen (FiO₂) 0.6, and I:E ratio 1:2 for the VCV group and 2:1 for the IRV group; hemodynamics and respiratory mechanics were monitored and recorded after intubation (0 min), before pneumoperitoneum (10 mins), and after pneumoperitoneum (20 mins), 30, 40, 50, and 60 mins. IRV significantly improves the respiratory mechanics during pneumoperitoneum in the form of decreasing the peak pressure (Ppeak) and plateau pressure (Pplat) and improving the dynamic compliance, but the mean pressure (Pmean) was increased; it also increased the partial pressure of oxygen (arterial PO₂) significantly. No statistical significance was found regarding the demographic data or the hemodynamics.

Conclusion

IRV is superior to conventional VCV in morbidly obese patients undergoing laparoscopic sleeve gastrectomy as it improves respiratory mechanics and oxygenation.

Effects of intraoperative inverse ratio ventilation on postoperative pulmonary function tests in the patients undergoing laparoscopic cholecystectomy: A prospective single blind study

Background and Aims:

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).

Methods:

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.

Results:

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.

Conclusion:

Intraoperative IRV led to reduced airway pressures; however, it did not prevent deterioration of PFTs in postoperative period.

[Inverse ratio ventilation combined with PEEP in infants undergoing thoracoscopic surgery with one lung ventilation for lung cystadenomas: a randomized control trial of 63 cases]

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.

Role of laryngeal mask airway in laparoscopic cholecystectomy

Laparoscopic cholecystectomy is one of the most commonly performed surgical procedures and the laryngeal mask airway (LMA) is the most common supraglottic airway device used by the anesthesiologists to manage airway during general anesthesia. Use of LMA has some advantages when compared to endotracheal intubation, such as quick and ease of placement, a lesser requirement for neuromuscular blockade and a lower incidence of postoperative morbididy. However, the use of the LMA in laparoscopy is controversial, based on a concern about increased risk of regurgitation and pulmonary aspiration. The ability of these devices to provide optimal ventilation during laparoscopic procedures has been also questioned. The most important parameter to secure an adequate ventilation and oxygenation for the LMA under pneumoperitoneum condition is its seal pressure of airway. A good sealing pressure, not only state correct patient ventilation, but it reduces the potential risk of aspiration due to the better seal of airway. In addition, the LMAs incorporating a gastric access, permitting a safe anesthesia based on these commented points. We did a literature search to clarify if the use of LMA in preference to intubation provides inadequate ventilation or increase the risk of aspiration in patients undergoing laparoscopic cholecystectomy. We found evidence stating that LMA with drain channel achieves adequate ventilation for these procedures. Limited evidence was found to consider these devices completely safe against aspiration. However, we observed that the incidence of regurgitation and aspiration associated with the use of the LMA in laparoscopic surgery is very low.

Effects of a 1:1 inspiratory to expiratory ratio on respiratory mechanics and oxygenation during one-lung ventilation in patients with low diffusion capacity of lung for carbon monoxide: a crossover study

STUDY OBJECTIVE

To investigate the effects of a 1:1 inspiratory-to-expiratory (I:E) ventilation ratio on oxygenation and respiratory mechanics during one-lung ventilation (OLV) in patients with low diffusion capacity of lung for carbon monoxide (DLCO).

DESIGN

Prospective, randomized, crossover study.

SETTING

Operating room, university hospital.

PATIENTS

Twenty-six patients with a preoperative DLCO less than 80% who were scheduled for lung lobectomy requiring OLV under general anesthesia.

INTERVENTIONS

In the first group (n = 13), OLV was begun with a 1:1 I:E ratio, which was switched to a 1:2 I:E ratio after 30 minutes. In the second group (n = 13), the modes of ventilation were performed in the opposite order. Pressure-controlled ventilation with 5 cm H2O of positive end-expiratory pressure and a tidal volume of 5 to 8 mL/kg was applied during OLV.

MEASUREMENTS

Arterial and central venous blood gas analyses were recorded and used to calculate intrapulmonary shunt fraction and physiologic dead space. These measurements were taken at 4 time points: 10 minutes after two-lung ventilation in the lateral decubitus position, 30 minutes after initiation of OLV, 30 minutes after switching the I:E ratio, and 10 minutes after two-lung ventilation was resumed.

MAIN RESULTS

There was no difference in arterial oxygen tension during OLV between the 2 groups (P = .429). Arterial carbon dioxide tension and peak airway pressure were lower in the 1:1 group than in the 1:2 group (P = .003; P = .008). Physiologic dead space was also decreased in the 1:1 I:E ratio group (P = .003). Mean airway pressure and dynamic compliance were higher in the 1:1 group (P = .003; P = .007).

CONCLUSIONS

Pressure-controlled ventilation with a 1:1 I:E ventilation ratio did not improve oxygenation in patients with low DLCO during OLV compared with a 1:2 I:E ventilation ratio. However, it did provide benefits in terms of respiratory mechanics and increased the efficiency of alveolar ventilation during OLV.

Equal ratio ventilation (1:1) improves arterial oxygenation during laparoscopic bariatric surgery: A crossover study

Background:

Hypoxaemia and high peak airway pressure (Ppeak) are common anesthetic problems during laparoscopic bariatric surgery. Several publications have reported the successful improvement in arterial oxygenation using positive end expiratory pressure and alveolar recruitment maneuver, however, high peak airway pressure during laparoscopic bariatric surgery may limit the use of both techniques. This study was designed to determine whether equal I:E (inspiratory-to-expiratory) ratio ventilation (1:1) improves arterial oxygenation with parallel decrease in the Ppeak values.

Methods:

Thirty patients with a body mass index ≥40 kg/m² scheduled for laparoscopic bariatric surgery were randomized, after creation of pneumoperitoneum, to receive I:E ratio either 1:1 (group 1, 15 patients) or 1:2 (group 2, 15 patients). After a stabilization period of 30 min, patients were crossed over to the other studied I:E ratio. Ppeak, mean airway pressure (Pmean), dynamic compliance (Cdyn), arterial blood gases and hemodynamic data were collected at the end of each stabilization period.

Results:

Ventilation with I: E ratio of 1:1 significantly increased partial pressure of O₂ in the arterial blood (PaO₂), Pmean and Cdyn with concomitant significant decrease in Ppeak compared to ventilation with I: E ratio of 1:2. There were no statistical differences between the two groups regarding the mean arterial pressure, heart rate, respiratory rate, end tidal CO₂ or partial pressure of CO₂ in the arterial blood.

Conclusion:

Equal ratio ventilation (1:1) is an effective technique in increase PaO₂ during laparoscopic bariatric surgery. It increases Pmean and Cdyn while decreasing Ppeak without adverse respiratory or hemodynamic effects.