Respiratory effects of lung recruitment maneuvers depend on the recruitment-to-inflation ratio in patients with COVID-19-related acute respiratory distress syndrome

Background In the context of acute respiratory distress syndrome (ARDS), the response to lung recruitment maneuvers (LRMs) varies considerably from one patient to another and so is difficult to predict. The aim of the study was to determine whether or not the recruitment-to-inflation (R/I) ratio could differentiate between patients according to the change in lung mechanics during the LRM. Methods We evaluated the changes in gas exchange and respiratory mechanics induced by a stepwise LRM at a constant driving pressure of 15 cmH2O during pressure-controlled ventilation. We assessed lung recruitability by measuring the R/I ratio. Patients were dichotomized with regard to the median R/I ratio. Results We included 30 patients with moderate-to-severe ARDS and a median [interquartile range] R/I ratio of 0.62 [0.42–0.83]. After the LRM, patients with high recruitability (R/I ratio ≥ 0.62) presented an improvement in the PaO2/FiO2 ratio, due to significant increase in respiratory system compliance (33 [27–42] vs. 42 [35–60] mL/cmH2O; p < 0.001). In low recruitability patients (R/I < 0.62), the increase in PaO2/FiO2 ratio was associated with a significant decrease in pulse pressure as a surrogate of cardiac output (70 [55–85] vs. 50 [51–67] mmHg; p = 0.01) but not with a significant change in respiratory system compliance (33 [24–47] vs. 35 [25–47] mL/cmH2O; p = 0.74). Conclusion After the LRM, patients with high recruitability presented a significant increase in respiratory system compliance (indicating a gain in ventilated area), while those with low recruitability presented a decrease in pulse pressure suggesting a drop in cardiac output and therefore in intrapulmonary shunt.

Lung recruitment improves the efficacy of intubation-surfactant-extubation treatment for respiratory distress syndrome in preterm neonates, a randomized controlled trial

Background Lung recruitment is a maneuver used to decrease the length of intubation in preterm neonates. This study aimed to compare the therapeutic efficacy of lung recruitment plus intubation-surfactant-extubation (INSURE) procedure and INSURE alone for the preterm neonates with respiratory distress syndrome. Methods From 2017 to 2019, 184 preterm neonates (gestational age 24–32 weeks) with respiratory distress syndrome were enrolled and randomized into the lung recruitment group receiving lung recruitment (25 cm H2O, 15 s) plus INSURE and the control group receiving INSURE only. The primary outcome was the need for mechanical ventilation (MV) within 72 h after extubation. The secondary outcomes included duration of MV, noninvasive ventilation, total oxygen therapy, hospitalization time, and complications. Results Compared to the control group, the lung recruitment group had a significantly lower proportion of preterm neonates requiring MV within 72 h after extubation (23% vs. 38%, P = 0.025) and pulmonary surfactant administration, as well as a shorter MV duration. There was no significant difference in the incidences of complications (all P > 0.05) and in-hospital mortality (2% vs. 4%, P = 0.4) between the lung recruitment group and control group. Multivariate logistic regression analysis demonstrated that the control group had a 2.17-time higher risk of requiring MV than the lung recruitment group (AOR: 2.17, 95% CI: 1.13–4.18; P = 0.021). Compared with infants with a normotensive mother, infants with a hypertensive mother have a 2.41-time higher risk of requiring MV (AOR: 2.41, 95% CI: 1.15–5.05; P = 0.020). Conclusion Lung recruitment plus INSURE can reduce the need for MV within 72 h after extubation and did not increase the incidence of complications and mortality. Trial registration Chinese Clinical Trial Registry ChiCTR1800020125, retrospectively registered on December 15, 2018.

The Effect of Ultrasound-Guided Lung Recruitment Maneuvers On Atelectasis In Lung-Healthy Patients Undergoing Laparoscopic Gynecologic Surgery: a Randomized Controlled Trial

BackgroundAtelectasis is a major cause of hypoxemia during general anesthesia and postoperative pulmonary complications (PPCs).Some previous reported that the combined use of lung recruitment procedures (LRMs) and positive end-expiratory pressure (PEEP) in mechanical ventilation mode contributes to the avoidance of PPCs in patients after general anesthesia, while others suggest that the use of LRMs makes patients more susceptible to hemodynamic disturbances and lung injury, and is of limited potential to decrease the incidence of PPCs. From this perspective, controversy exists as to whether LRMs should be routinely applied to surgical patients. More importantly, corresponding clinical studies are also lacking. Therefore, this trial was conducted with the aim of solving the above problem.MethodsIn current clinical trial, patients undergoing laparoscopic gynecologic surgery with healthy lungs were randomized to the recruitment maneuvers group (RM group; 6 cm H2O PEEP and RMs) and the control group (C group; 6 cm H2O PEEP and no RMs). Lung ultrasound was performed on patients at five separate time points. During mechanical ventilation, patients in the RM group received ultrasound-guided pulmonary resuscitation when atelectasis was detected, while the C group did not intervene. Lung ultrasound scores were used to evaluate the incidence and severity of atelectasis.ResultsAfter LRMs, the incidence of atelectasis was significantly lower in the RM group (40%) than in the C group (80%) 15 minutes after arrival in the post-anesthesia care unit (PACU), and this difference did not persist for 24 hours after surgery. Meanwhile, postoperative pulmonary complications showed no difference between the two groups.ConclusionsThe combination of LRMs and PEEP decreased the incidence of atelectasis 15 minutes after admission to the PACU, but did not improve PPCs in adults with healthy lungs. Hence, for lung-healthy patients undergoing gynecological laparoscopic surgery, we do not recommend routine recruitment maneuvers. Trial registration: (prospectively registered): ChiCTR2000033529. Registered on 6/4/2020.

Changes in stroke volume induced by lung recruitment maneuver can predict fluid responsiveness during intraoperative lung-protective ventilation in prone position

Background The present study aimed to evaluate the reliability of hemodynamic changes induced by lung recruitment maneuver (LRM) in predicting stroke volume (SV) increase after fluid loading (FL) in prone position. Methods Thirty patients undergoing spine surgery in prone position were enrolled. Lung-protective ventilation (tidal volume, 6–7 mL/kg; positive end-expiratory pressure, 5 cmH2O) was provided to all patients. LRM (30 cmH2O for 30 s) was performed. Hemodynamic variables including mean arterial pressure (MAP), heart rate, SV, SV variation (SVV), and pulse pressure variation (PPV) were simultaneously recorded before, during, and at 5 min after LRM and after FL (250 mL in 10 min). Receiver operating characteristic curves were generated to evaluate the predictability of SVV, PPV, and SV decrease by LRM (ΔSVLRM) for SV responders (SV increase after FL > 10%). The gray zone approach was applied for ΔSVLRM. Results Areas under the curve (AUCs) for ΔSVLRM, SVV, and PPV to predict SV responders were 0.778 (95% confidence interval: 0.590–0.909), 0.563 (0.371–0.743), and 0.502 (0.315–0.689), respectively. The optimal threshold for ΔSVLRM was 30% (sensitivity, 92.3%; specificity, 70.6%). With the gray zone approach, the inconclusive values ranged 25 to 75% for ΔSVLRM (including 50% of enrolled patients). Conclusion In prone position, LRM-induced SV decrease predicted SV increase after FL with higher reliability than traditional dynamic indices. On the other hand, considering the relatively large gray zone in this study, future research is needed to further improve the clinical significance. Trial registration UMIN Clinical Trial Registry UMIN000027966. Registered 28th June 2017.

Effect of Ultrasound-guided Lung Recruitment Maneuvers on Atelectasis in Lung-healthy Patients Undergoing Laparoscopic Gynecologic Surgery: a Randomized Controlled Trial

BackgroundAtelectasis is a major cause of hypoxemia during general anesthesia and postoperative pulmonary complications (PPCs).Some previous reported that the combined use of lung recruitment procedures (LRMs) and positive end-expiratory pressure (PEEP) in mechanical ventilation mode contributes to the avoidance of PPCs in patients after general anesthesia, while others suggest that the use of LRMs makes patients more susceptible to hemodynamic disturbances and lung injury, and is of limited potential to decrease the incidence of PPCs. From this perspective, controversy exists as to whether LRMs should be routinely applied to surgical patients. More importantly, corresponding clinical studies are also lacking. Therefore, this trial was conducted with the aim of solving the above problem.MethodsIn current clinical trial, patients undergoing laparoscopic gynecologic surgery with healthy lungs were randomized to the recruitment maneuvers group (RM group; 6 cm H2O PEEP and RMs) and the control group (C group; 6 cm H2O PEEP and no RMs). Lung ultrasound was performed on patients at five separate time points. During mechanical ventilation, patients in the RM group received ultrasound-guided pulmonary resuscitation when atelectasis was detected, while the C group did not intervene. Lung ultrasound scores were used to evaluate the incidence and severity of atelectasis.ResultsAfter LRMs, the incidence of atelectasis was significantly lower in the RM group (40%) than in the C group (80%) 15 minutes after arrival in the post-anesthesia care unit (PACU), and this difference did not persist for 24 hours after surgery. Meanwhile, postoperative pulmonary complications showed no difference between the two groups.ConclusionsThe combination of LRMs and PEEP decreased the incidence of atelectasis 15 minutes after admission to the PACU, but did not improve PPCs in adults with healthy lungs. Hence, for lung-healthy patients undergoing gynecological laparoscopic surgery, we do not recommend routine recruitment maneuvers. Trial registration (prospectively registered)ChiCTR2000033529. Registered on June 4, 2020.

Lung Recruitment Using High-Frequency Oscillation Volume Guarantee in Preterm Infants with Evolving Bronchopulmonary Dysplasia

<b><i>Background:</i></b> Stepwise lung recruitment maneuvers (LRMs) may be used in ventilated preterm infants. However, its use in high-frequency oscillation with volume guarantee (HFO-VG) is not well studied. <b><i>Methods:</i></b> Preterm infants treated with HFO-VG who had LRMs were identified. Patient and respiratory parameters were recorded. <b><i>Results:</i></b> Ten infants, median GA 25⁺⁶ (IQR 24⁺²–27⁺⁰) weeks, and 21 LRMs were identified. LRMs were performed at a median age of 26 days, with a starting MAP of 16 (14–17) cm H₂O and the highest MAP of 23.5 (22.0–24.8) cm H₂O. Most (76%) resulted in immediate improved SpO₂/FiO_2. There were no sustained differences in median oxygen saturation index (8.4 vs. 9, <i>p</i> = 0.09), SpO₂/FiO₂ (1.8 vs. 1.8, <i>p</i> = 0.8), ∆P (21 vs. 23, <i>p</i> = 0.64), or transcutaneous CO₂ (58 vs. 60, <i>p</i> = 0.84) in 24 h before and after LRMs. <b><i>Conclusions:</i></b> In preterm infants with evolving bronchopulmonary dysplasia, LRMs on HFO-VG did not result in sustained improvement to oxygenation or ventilation.