Lung Recruitment Maneuver Research Articles

Variations of pulse pressure and central venous pressure may predict fluid responsiveness in mechanically ventilated patients during lung recruitment manoeuvre: an ancillary study

BackgroundMaintaining a constant driving pressure during a prolonged sigh breath lung recruitment manoeuvre (LRM) from 20 to 45 cmH20 peak inspiratory pressure in mechanically ventilated patients has been shown to be a functional test to predict fluid responsiveness (FR) when using a linear regression model of hemodynamic parameters, such as central venous pressure (CVP) and pulse pressure (PP). However, two important limitations have been raised, the use of high ventilation pressures and a regression slope calculation that is difficult to apply at bedside. This ancillary study aimed to reanalyse absolute variations of CVP (ΔCVP) and PP (ΔPP) values at lower stages of the LRM, (40, 35, and 30 cm H20 of peak inspiratory pressure) for their ability to predict fluid responsiveness.MethodsRetrospective analysis of a prospective study data set in 18 mechanically ventilated patients, in an intensive care unit. CVP, systemic arterial pressure parameters and stroke volume (SV) were recorded during prolonged LRM followed by a 500 mL crystalloid volume expansion. Patients were considered as fluid responders if SV increased more than 10%. Receiver-operating curves (ROC) analysis with the corresponding grey zone approach were performed.ResultsAreas under the ROC to predict fluid responsiveness for ΔCVP and ΔPP were not different between the successive stepwise increase of inspiratory pressures [0.88 and 0.89 for ΔCVP at 45 and 30 cm H20 (P = 0.89), respectively, and 0.92 and 0.95 for ΔPP at 45 and 30 cm H20, respectively (P = 0.51)]. Using a maximum of 30 cmH2O inspiratory pressure during the LRM, ΔCVP and ΔPP had a threshold value to predict fluid responsiveness of 2 mmHg and 4 mmHg, with sensitivities of 89% and 89% and specificities of 67% and 89%, respectively. Combining ΔPP and ΔCVP decreased the proportion of the patients in the grey zone from 28 to 11% and showed a sensitivity of 88% and a specificity of 83%.ConclusionsA stepwise PEEP elevation recruitment manoeuvre of up to 30 cm H20 may predict fluid responsiveness as well as 45 cm H20. The combination of ΔPP and ΔCVP optimizes the categorization of responder and non-responder patients.

Effects of ultrasound-guided alveolar recruitment manoeuvres compared with sustained inflation or no recruitment manoeuvres on atelectasis in laparoscopic gynaecological surgery as assessed by ultrasonography: a randomized clinical trial

BackgroundThe majority of patients may experience atelectasis under general anesthesia, and the Trendelenburg position and pneumoperitoneum can aggravate atelectasis during laparoscopic surgery, which promotes postoperative pulmonary complications. Lung recruitment manoeuvres have been proven to reduce perioperative atelectasis, but it remains controversial which method is optimal. Ultrasonic imaging can be conducive to confirming the effect of lung recruitment manoeuvres. The purpose of our study was to assess the effects of ultrasound-guided alveolar recruitment manoeuvres by ultrasonography on reducing perioperative atelectasis and to check whether the effects of recruitment manoeuvres under ultrasound guidance (visual and semiquantitative) on atelectasis are superior to sustained inflation recruitment manoeuvres (classical and widely used) in laparoscopic gynaecological surgery.MethodsIn this randomized, controlled, double-blinded study, women undergoing laparoscopic gynecological surgery were enrolled. Patients were randomly assigned to receive either lung ultrasound-guided alveolar recruitment manoeuvres (UD group), sustained inflation alveolar recruitment manoeuvres (SI group), or no RMs (C group) using a computer-generated table of random numbers. Lung ultrasonography was performed at four predefined time points. The primary outcome was the difference in lung ultrasound score (LUS) among groups at the end of surgery.ResultsLung ultrasound scores in the UD group were significantly lower than those in both the SI group and the C group immediately after the end of surgery (7.67 ± 1.15 versus 9.70 ± 102, difference, -2.03 [95% confidence interval, -2.77 to -1.29], P < 0.001; 7.67 ± 1.15 versus 11.73 ± 1.96, difference, -4.07 [95% confidence interval, -4.81 to -3.33], P < 0.001;, respectively). The intergroup differences were sustained until 30 min after tracheal extubation (9.33 ± 0.96 versus 11.13 ± 0.97, difference, -1.80 [95% confidence interval, -2.42 to -1.18], P < 0.001; 9.33 ± 0.96 versus 10.77 ± 1.57, difference, -1.43 [95% confidence interval, -2.05 to -0.82], P < 0.001;, respectively). The SI group had a significantly lower LUS than the C group at the end of surgery (9.70 ± 1.02 versus 11.73 ± 1.96, difference, -2.03 [95% confidence interval, -2.77 to -1.29] P < 0.001), but the benefit did not persist 30 min after tracheal extubation.ConclusionsDuring general anesthesia, ultrasound-guided recruitment manoeuvres can reduce perioperative aeration loss and improve oxygenation. Furthermore, these effects of ultrasound-guided recruitment manoeuvres on atelectasis are superior to sustained inflation recruitment manoeuvres.Trial registrationChictr.org.cn, ChiCTR2100042731, Registered 27 January 2021, www.chictr.org.cn.

Evaluation of intra-cranial pressure changes by measuring the optic nerve sheath diameter during the lung recruitment maneuver in patients with acute respiratory distress syndrome: A prospective study.

The lung recruitment maneuver (LRM) applied in acute respiratory distress syndrome (ARDS) may increase the intra-cranial pressure (ICP). This study evaluated the effect of LRM on intra-cranial pressure changes in patients with ARDS by measuring the optic nerve sheath diameter (ONSD). LRM was applied to patients undergoing follow-up for ARDS, with a positive pressure of 30 cmH2O for 30 s. ONSD on ultra-sonography, dynamic lung compliance (Cdyn), oxygen saturation (SpO2), and hemodynamic parameters were measured before (T0), immediately after (T1), and 10 min after (T2) LRM. The primary endpoint was the effect of LRM on ONSD changes. The secondary endpoints included the effect of LRM on Cdyn, SpO2 change, and relationship between Cdyn and ONSD changes. The study included 60 patients. ONSD was higher at T1 than at T0 (median [interquartile range]: 5.13 [0.4] vs. 5.3 [0.3] mm, P < 0.001) but was similar at T0 and T2 (5.13 [0.4] vs. 5.09 [0.37] mm, P = 0.36). Cdyn and SpO2 were significantly higher at T1 and T2 than at T0 (Cdyn: 22.3 [5.8] vs. 23.7 [7.5] vs. 19.4 [6.6] mL/cmH2O, P < 0.001; SpO2: 90[2] vs. 92[4] vs. 88[4] %, P = 0.013). A significant correlation existed between Cdyn and ONSD changes, which increased at T2 compared to T0 (P < 0.001). LRM applied in ARDS causes a short-term increase in ONSD. However, Cdyn increases 10 min after LRM and causes ONSD, thereby leading to a decrease in ICP.

Safe Inspiratory Pressures Threshold in Lung Recruitment Maneuvers: An In Vivo Neonatal ARDS Model.

The aim of this study was to define the level of peak inspiratory pressure (PIP) and mean airway pressure ([Formula: see text]) at which a pneumothorax is produced in an in vivo ARDS neonate model. In addition, we analyzed the hemodynamic response and cerebral parameters during the progressive increase of intrathoracic pressure. We designed a prospective, experimental study with 11 Landrace × Large White pigs < 48 h from their birth. With the pigs under general anesthesia, tracheal intubation, invasive hemodynamic monitoring with a pediatric arterial thermodilution catheter, intracranial pressure, cerebral oximetry through near-infrared spectroscopy, and bilateral chest tube catheterization were performed. The ARDS model was developed with bronchoalveolar lavages. The rise in inspiratory pressure was performed achieved by increasing PEEP in stepwise increments at a constant driving pressure. PEEP was increased 5 cm H2O every 2 min until a pneumothorax was observed. A descriptive analysis, a Kaplan-Meier curve, and a regression analysis by using a generalized estimation equation were performed. A pneumothorax was observed in a median (interquartile range [IQR]) [Formula: see text] of 54 (46-56) cm H2O and median (IQR) PIP of 65 (58-73) cm H2O; asystole at median (IQR) [Formula: see text] of 49 (36-54) cm H2O and median (IQR) PIP of 60 (48-65) cm H2O. Hemodynamic changes in the median artery pressure, cardiac output, and myocardial contractility were observed above the range of [Formula: see text] of 14 cm H2O (PIP 25 and PEEP 10 cm H2O). Disturbances in intracranial pressure and cerebral oximetry through near-infrared spectroscopy appeared when deep hypotension and asystole occurred. A progressive increase of PEEP at a constant driving pressure did not increase severe adverse events at the range of pressures that we routinely use in neonates with ARDS. Asystole, pneumothorax, and cerebral compromise appeared at high intrathoracic ranges of pressure. Hemodynamics must be strictly monitored in all patients during the performance of lung recruitment maneuvers because hemodynamic deflections emerge early, at a range of pressures commonly used in ventilated neonates with ARDS.

Lung UltraSound Targeted Recruitment (LUSTR): A Novel Protocol to Optimize Open Lung Ventilation in Critically Ill Neonates.

This study investigated the effectiveness of an original Lung UltraSound Targeted Recruitment (LUSTR) protocol to improve the success of lung recruitment maneuvers (LRMs), which are performed as a rescue approach in critically ill neonates. All the LUSTR maneuvers, performed on infants with an oxygen saturation/fraction of inspired oxygen (S/F) ratio below 200, were included in this case−control study (LUSTR-group). The LUSTR-group was matched by the initial S/F ratio and underlying respiratory disease with a control group of lung recruitments performed following the standard oxygenation-guided procedure (Ox-group). The primary outcome was the improvement of the S/F ratio (Delta S/F) throughout the LRM. Secondary outcomes included the rate of air leaks. Each group was comprised of fourteen LRMs. As compared to the standard approach, the LUSTR protocol was associated with a higher success of the procedure in terms of Delta S/F (110 ± 47.3 vs. 64.1 ± 54.6, p = 0.02). This result remained significant after adjusting for confounding variables through multiple linear regressions. The incidence of pneumothorax was lower, although not reaching statistical significance, in the LUSTR-group (0 vs. 14.3%, p = 0.15). The LUSTR protocol may be a more effective and safer option than the oxygenation-based procedure to guide open lung ventilation in neonates, potentially improving ventilation and reducing the impact of ventilator-induced lung injury.

Validation of lung sonography in the implementation of open lung strategy as a recruitment maneuver versus traditional sustained inflation in acute respiratory distress syndrome patients

Introduction Acute respiratory distress syndrome (ARDS) is a serious problem in critically ill patients with high mortality rates. Lung recruitment maneuvers (RM) are important in the treatment of ARDS with an aim to improve oxygenation. There are many approved methods for lung recruitment like the traditional sustained inflation technique and the stepladder positive end-expiratory pressure (PEEP) titration technique. The traditional methods to evaluate RM like computed tomography and pressure–volume curves showed some limitation and disadvantages. Thus, bedside ultrasonography (US) could be a safe bedside tool to evaluate lung aeration and the effectiveness of RM defining the optimum PEEP needed and preventing lung overdistension. Aim To evaluate the usefulness of lung US as a guide to follow up RM by PEEP titration technique in comparison to sustained inflation technique. Patients and methods In all, 40 ARDS patients were segregated into two groups: group 1 included 20 patients who were subjected to traditional sustained inflation RM and group 2 included 20 patients were subjected to sonar-guided lung recruitment. US scoring, PO2, PO2/FiO2, and lung compliance were used to evaluate the pulmonary recruitment end point defining the best PEEP. Results Lung compliance, PO2, and PO2/FiO2 were significantly increased after RM in both groups (P&lt;0.05); however, there was no statistically significant difference between the two groups. The best PEEP in group 1 and group 2 were 20.60±3.485 and 15.90±5.340, respectively, with a significant difference between the two groups (P=0.002). There was no statically significant difference between the two groups regarding complication, vent days and ICU days. Conclusion Bedside US can be very useful in the evaluation and management of mechanically ventilated patients in ICUs and to guide the RM in ARDS patients. There is no significant difference between the sustained inflation RM and the sonar-guided stepwise PEEP titration RM regarding oxygenation and compliance except for the level of PEEP reached, which is lower in the stepwise PEEP titration group giving less potentiality for complications.

The effect of ultrasound-guided lung recruitment maneuvers on atelectasis in lung-healthy patients undergoing laparoscopic gynecologic surgery: a randomized controlled trial

BackgroundAtelectasis is the primary cause of hypoxemia during general anesthesia. This study aimed to evaluate the impact of the combination of recruitment maneuvers (RM) and positive end-expiratory pressure (PEEP) on the incidence of atelectasis in adult women undergoing gynecologic laparoscopic surgery using pulmonary ultrasound.MethodsIn this study, 42 patients with healthy lungs undergoing laparoscopic gynecologic surgery were randomly divided into the recruitment maneuver group (RM group; 6 cm H2O PEEP and RM) or the control group (C group; 6 cm H2O PEEP and no RM), 21 patients in each group. Volume-controlled ventilation was used in all selected patients, with a tidal volume of 6–8 mL·kg−1 of ideal body weight. When atelectasis was detected, patients in the RM group received ultrasound-guided RM, while those in the C group received no intervention. The incidence and severity of atelectasis were determined using lung ultrasound scores.ResultsA total of 41 patients were investigated. The incidence of atelectasis was lower in the RM group (40%) than in the C group (80%) 15 min after arrival in the post-anesthesia care unit (PACU). Meanwhile, lung ultrasound scores (LUSs) were lower in the RM group compared to the C group. In addition, the differences in the LUS between the two groups were mainly due to the differences in lung ultrasound scores in the posterior regions. However, this difference did not persist after 24 h of surgery.ConclusionsIn conclusion, the combination of RM and PEEP could reduce the incidence of atelectasis in patients with healthy lungs 15 min after arrival at the PACU; however, it disappeared within 24 h after surgery.Trial registration(Prospectively registered): ChiCTR2000033529. Registered on 4/6/2020.

Extracorporeal membrane oxygenation rescue for severe pneumocystis pneumonia with the Macklin effect: a case report

BackgroundPneumocystis jirovecii pneumonia (PJP) in an immunocompromised host is often associated with the Macklin effect, which can progress to spontaneous pneumomediastinum (SPM), subcutaneous emphysema (SCE), and pneumothorax (PNX). Diagnosing the causative organism of these conditions in non-HIV infected patients and treating hypoxemia while preventing further lung damage can be challenging. This study examines the case of a non-HIV infected male with SPM, SCE, and PNX secondary to severe Pneumocystis jirovecii (PJ) infection.Case presentationA 53-year-old male with pure red cell aplasia (PRCA) was admitted with fever, dry cough, and shortness of breath. His respiratory function progressively deteriorated due to the development of SPM, SCE, and PNX, eventually requiring endotracheal intubation and invasive ventilation. As a result of high pressure in his airways occasioned by lung recruitment maneuvers, his pulmonary parameters worsened, necessitating veno-venous (VV) extracorporeal membrane oxygenation (ECMO) therapy. The early initiation of VV-ECMO facilitated ultra-protective lung ventilation and prevented the progression of SPM, SCE, and PNX. Traditional diagnostic assays were unrevealing, whereupon the patient resorted to the metagenomic next-generation sequencing technology for uncovering potential pathogens. Consequently, we detected a significantly higher infection by PJ in the patient’s bronchoscopy lavage fluid. Finally, the patient was successfully treated with appropriate antimicrobials and was decannulated after nine days of ECMO support.ConclusionsSPM, SCE, and PNX are rare clinical manifestations of PJP. However, they can be considered as poor prognostic factors of the infection. Physicians should, therefore, be alert to the possibility of PJP in immunocompromised patients.

Prediction of Fluid Responsiveness by the Effect of the Lung Recruitment Maneuver on the Perfusion Index in Mechanically Ventilated Patients During Surgery.

IntroductionExcessive or inadequate fluid administration during perioperative period affects outcomes. Adjustment of volume expansion (VE) by performing fluid responsiveness (FR) test plays an important role in optimizing fluid infusion. Since changes in stroke volume (SV) during lung recruitment maneuver (LRM) can predict FR, and peripheral perfusion index (PI) is related to SV; therefore, we hypothesized that the changes in PI during LRM (ΔPILRM) could predict FR during perioperative period.MethodsPatients who were scheduled for elective non-laparoscopic surgery under general anesthesia with a mechanical ventilator and who required VE (250 mL of crystalloid solution infusion over 10 min) were included. Before VE, LRM was performed by a continuous positive airway pressure of 30 cm H2O for 30 sec; hemodynamic variables with their changes (PI, obtained by pulse oximetry; and ΔPILRM, calculated by using [(PI before LRM—PI after LRM)/PI before LRM]*100) were obtained before and after LRM. After SV (measured by esophageal doppler) and PI had returned to the baseline values, VE was infused, and the values of these variables were recorded again, before and after VE. Fluid responders (Fluid-Res) were defined by an increase in SV ≥10% after VE. Receiver operating characteristic curves of the baseline values and ΔPILRM were constructed and reported as areas under the curve (AUC) with 95% confidence intervals, to predict FR.ResultsOf 32 mechanically ventilated adult patients included, 13 (41%) were in the Fluid-Res group. Before VE and LRM, there were no differences in the mean arterial pressure (MAP), heart rate, SV, and PI between patients in the Fluid-Res and fluid non-responders (Fluid-NonRes) groups. After LRM, SV, MAP, and, PI decreased in both groups, ΔPILRM was greater in the Fluid-Res group than in Fluid-NonRes group (55.2 ± 17.8% vs. 35.3 ± 17.3%, p < 0.001, respectively). After VE, only SV and cardiac index increased in the Fluid-Res group. ΔPILRM had the highest AUC [0.81 (0.66–0.97)] to predict FR with a cut-off value of 40% (sensitivity 92.3%, specificity 73.7%).ConclusionsΔPILRM can be applied to predict FR in mechanical ventilated patients during the perioperative period.

Flexible Bronchoscopy in Pediatric Venovenous Extracorporeal Membrane Oxygenation.

Pediatric patients with ARDS will on occasion need venovenous extracorporeal membrane oxygenation (VV-ECMO) for organ support. As these patients recover, they may benefit from lung recruitment maneuvers including flexible bronchoscopy (FB). The objective of this study was to assess the clinical course of patients who underwent FB while on VV-ECMO for ARDS. This was a secondary analysis of a retrospective multi-center cohort at 10 United States pediatric academic quaternary care centers. Data were collected on 204 subjects age 14 d-18 y on VV-ECMO. 271 FBs were performed on 129 (63%) subjects. Pre-FB tidal volume was 1.8 mL/kg compared to 2.22 mL/kg following FB (P = .007). Dynamic compliance also improved from pre-FB to post-FB (2.23 vs 3.04 mL/cm H2O, P = .005). There was a low incidence of complications following FB (3.1%). Subjects in the FB group had fewer ECMO-free days (EFDs) (17.9 vs 22.1 d, P < .001), fewer ventilator-free days (VFDs) (40.0 vs 46.5 d, P = .001), and longer ICU length of stay (LOS) (18 vs 32 d, P < .001). Subjects in the early versus late FB group had more EFDs (19.4 vs 15.2 d, P = .003), more VFDs (43.0 vs 34.0 d, P = .004), and shorter ICU LOS (27.5 vs 35.5 d, P = .045). Mortality in the subjects who had at least one FB was 27.1% compared to 40% in the subjects who did not have a FB while on VV-ECMO (P = .057). FB can be performed on patients while anticoagulated on VV-ECMO with a low incidence of complications. FB may be beneficial especially when performed early in the course of VV-ECMO.

Physiological benefits of lung recruitment in the semi-lateral position after laparoscopic surgery: a randomized controlled study

We evaluated the physiological benefits of performing lung recruitment maneuver (LRM) in the semi-lateral position compared in the supine position. Seventy-nine patients undergoing laparoscopic prostatectomy were randomly assigned to either the supine or semi-lateral group according to body position during the LRM. At the end of surgery, LRM (35 cmH2O for 20 s) was performed twice in the assigned posture. The primary outcome was the maximal decrease in systolic arterial pressure during LRM. Secondary outcomes were changes in PaO2/FiO2 and the regional lung volume distribution after LRM. The decrease in systolic arterial pressure during the LRM was significantly higher in the supine group than in the semi-lateral group (mean ± standard deviation, [−] 27.6 ± 14.6% vs. [−] 18.6 ± 9.9%, P = 0.001). Improvement in PaO2/FiO2 ratio after the LRM was evident in both groups but was more prominent in the semi-lateral group than in the supine group (median [interquartile range], 39.3% [20.2, 63.6] vs. 18.2% [8.4, 29.2], P = 0.001). Among the horizontal lung divisions, regional lung volume in the most dependent portion (the dorsal division) was significantly increased after the LRM only in the semi-lateral group (P = 0.024). Performing lung recruitment in a semi-lateral position protected against hemodynamic deterioration during the LRM and increased regional lung ventilation in the dependent portion of the lung, leading to an improvement in arterial oxygenation after laparoscopic procedures.Trial registration Clinical Research Information Service (https://cris.nih.go.kr/). Identifier: KCT0003756.

Efficacy analysis of the lung recruitment maneuver in correcting pulmonary atelectasis in neurological intensive care unit-a retrospective study.

BackgroundAtelectasis after supratentorial craniotomy is common. It can lead to the decrease of arterial partial pressure of oxygen (PaO2) in patients with neurosurgical intensive care units (NICU), and the recovery of neurological function is more and more difficult. However, due to the particularity of maintaining the stability of intracranial pressure (ICP), there are few reports on effective ways to alleviate atelectasis and improve oxygenation in patients with NICU effectively.MethodsA retrospective analysis was conducted to analyze the clinical data of patients with atelectasis who received lung recruitment maneuver in the NICU. This study collected data on 33 patients. Of these, 17 patients had traumatic brain injury and 16 patients had spontaneous intracranial hemorrhage. PaO2, oxygenation index (OI), tidal volume, positive end-expiratory pressure (PEEP), respiratory system compliance, plateau pressure, respiratory rate, minute ventilation and chest computed tomography (CT) or portable chest X-ray images were compared before and after recruitment. As for safety evaluation indicators, we reviewed the invasive arterial blood pressure, heart rate, heart rhythm, and subcutaneous emphysema in all patients. Before and after lung recruitment, the data were compared using the paired t-test and the Wilcoxon test.ResultsCompared with tidal volume 8.1 [6.85–10.05] mL/kg, minute ventilation volume (9.3±1.3 L/min), respiratory system compliance 60 [39–80] mL/cmH2O, respiratory rate 17 [16–21.5] breaths/min, PEEP 4 [4–6] cmH2O, plateau pressure 19 [17–23] cmH2O, PaO2 (104.2±33.17 mmHg) and OI (250.6±87.65 mmHg) before lung recruitment, tidal volume 9 [8.05–10.65] mL/kg, minute ventilation (9.7±1.1 L/min), respiratory system compliance 69 [50–82.5] mL/cmH2O, respiratory rate 17 [14–18.5] breaths/min, PEEP 4 [4–5] cmH2O, plateau pressure 18 [16–19.5] cmH2O, PaO2 (127.3±34.95 mmHg) and OI (306.9±96.52 mmHg) of patients were significantly improved after recruitment after recruitment (all P<0.05). In all patients, chest CT showed a decrease in atelectasis area and bilateral pulmonary exudates in 25 patients after lung recruitment maneuver. X-ray after recruitment in 2 patients showed increased lung tissue transparency and decreased ground-glass shadowing, while improvements were not obvious in 6 patients.ConclusionsFor patients diagnosed with atelectasis in the NICU, lung recruitment maneuver can improve atelectasis, increase PaO2, and improve oxygenation.

Association of Positive End-Expiratory Pressure and Lung Recruitment Selection Strategies with Mortality in Acute Respiratory Distress Syndrome: A Systematic Review and Network Meta-analysis.

Rationale: The most beneficial positive end-expiratory pressure (PEEP) selection strategy in patients with acute respiratory distress syndrome (ARDS) is unknown, and current practice is variable. Objectives: To compare the relative effects of different PEEP selection strategies on mortality in adults with moderate to severe ARDS. Methods: We conducted a network meta-analysis using a Bayesian framework. Certainty of evidence was evaluated using grading of recommendations assessment, development and evaluation methodology. Measurements and Main Results: We included 18 randomized trials (4,646 participants). Compared with a lower PEEP strategy, the posterior probability of mortality benefit from a higher PEEP without lung recruitment maneuver (LRM) strategy was 99% (risk ratio [RR], 0.77; 95% credible interval [CrI], 0.60-0.96, high certainty), the posterior probability of benefit of the esophageal pressure-guided strategy was 87% (RR, 0.77; 95% CrI, 0.48-1.22, moderate certainty), the posterior probability of benefit of a higher PEEP with brief LRM strategy was 96% (RR, 0.83; 95% CrI, 0.67-1.02, moderate certainty), and the posterior probability of increased mortality from a higher PEEP with prolonged LRM strategy was 77% (RR, 1.06; 95% CrI, 0.89-1.22, low certainty). Compared with a higher PEEP without LRM strategy, the posterior probability of increased mortality from a higher PEEP with prolonged LRM strategy was 99% (RR, 1.37; 95% CrI, 1.04-1.81, moderate certainty). Conclusions: In patients with moderate to severe ARDS, higher PEEP without LRM is associated with a lower risk of death than lower PEEP. A higher PEEP with prolonged LRM strategy is associated with increased risk of death when compared with higher PEEP without LRM.

Tidal volume significantly affects oxygenation in healthy pigs during high-frequency oscillatory ventilation compared to conventional ventilation

BackgroundThe role of high-frequency oscillatory ventilation (HFOV) has long been debated. Numerous studies documented its benefits, whereas several more recent studies did not prove superiority of HFOV over protective conventional mechanical ventilation (CV). One of the accepted explanations is that CV and HFOV act differently, including gas exchange.MethodsTo investigate a different level of coupling or decoupling between oxygenation and carbon dioxide elimination during CV and HFOV, we conducted a prospective crossover animal study in 11 healthy pigs. In each animal, we found a normocapnic tidal volume (VT) after the lung recruitment maneuver. Then, VT was repeatedly changed over a wide range while keeping constant the levels of PEEP during CV and mean airway pressure during HFOV. Arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) were recorded. The same procedure was repeated for CV and HFOV in random order.ResultsChanges in PaCO2 intentionally induced by adjustment of VT affected oxygenation more significantly during HFOV than during CV. Increasing VT above its normocapnic value during HFOV caused a significant improvement in oxygenation, whereas improvement in oxygenation during CV hyperventilation was limited. Any decrease in VT during HFOV caused a rapid worsening of oxygenation compared to CV.ConclusionA change in PaCO2 induced by the manipulation of tidal volume inevitably brings with it a change in oxygenation, while this effect on oxygenation is significantly greater in HFOV compared to CV.

Sequential lateral positioning as a new lung recruitment maneuver: an exploratory study in early mechanically ventilated Covid-19 ARDS patients

BackgroundA sequential change in body position from supine-to-both lateral positions under constant ventilatory settings could be used as a postural recruitment maneuver in case of acute respiratory distress syndrome (ARDS), provided that sufficient positive end-expiratory pressure (PEEP) prevents derecruitment. This study aims to evaluate the feasibility and physiological effects of a sequential postural recruitment maneuver in early mechanically ventilated COVID-19 ARDS patients.MethodsA cohort of 15 patients receiving lung-protective mechanical ventilation in volume-controlled with PEEP based on recruitability were prospectively enrolled and evaluated in five sequentially applied positions for 30 min each: Supine-baseline; Lateral-1st side; 2nd Supine; Lateral-2nd side; Supine-final. PEEP level was selected using the recruitment-to-inflation ratio (R/I ratio) based on which patients received PEEP 12 cmH2O for R/I ratio ≤ 0.5 or PEEP 15 cmH2O for R/I ratio > 0.5. At the end of each period, we measured respiratory mechanics, arterial blood gases, lung ultrasound aeration, end-expiratory lung impedance (EELI), and regional distribution of ventilation and perfusion using electric impedance tomography (EIT).ResultsComparing supine baseline and final, respiratory compliance (29 ± 9 vs 32 ± 8 mL/cmH2O; p < 0.01) and PaO2/FIO2 ratio (138 ± 36 vs 164 ± 46 mmHg; p < 0.01) increased, while driving pressure (13 ± 2 vs 11 ± 2 cmH2O; p < 0.01) and lung ultrasound consolidation score decreased [5 (4–5) vs 2 (1–4); p < 0.01]. EELI decreased ventrally (218 ± 205 mL; p < 0.01) and increased dorsally (192 ± 475 mL; p = 0.02), while regional compliance increased in both ventral (11.5 ± 0.7 vs 12.9 ± 0.8 mL/cmH2O; p < 0.01) and dorsal regions (17.1 ± 1.8 vs 18.8 ± 1.8 mL/cmH2O; p < 0.01). Dorsal distribution of perfusion increased (64.8 ± 7.3% vs 66.3 ± 7.2%; p = 0.01).ConclusionsWithout increasing airway pressure, a sequential postural recruitment maneuver improves global and regional respiratory mechanics and gas exchange along with a redistribution of EELI from ventral to dorsal lung areas and less consolidation.Trial registration ClinicalTrials.gov, NCT04475068. Registered 17 July 2020, https://clinicaltrials.gov/ct2/show/NCT04475068

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

BackgroundIn 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.MethodsWe 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.ResultsWe 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).ConclusionAfter 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.

Slope analysis for the prediction of fluid responsiveness by a stepwise PEEP elevation recruitment maneuver in mechanically ventilated patients

ObjectiveAssessment of fluid responsiveness is problematic in intensive care unit patients. Lung recruitment maneuvers (LRM) can be used as a functional test to predict fluid responsiveness. We propose a new test to predict fluid responsiveness in mechanically ventilated patients by analyzing the variations in central venous pressure (CVP) and systemic arterial parameters during a prolonged sigh breath LRM without the use of a cardiac output measuring device.DesignProspective observational cohort study.SettingIntensive Care Unit, Saint-Etienne University Central Hospital.PatientsPatients under mechanical ventilation, equipped with invasive arterial blood pressure, CVP, pulse contour analysis (PICCO™), requiring volume expansion, with no right ventricular dysfunction.Interventions.None.Measurements and main resultsCVP, systemic arterial parameters and stroke volume (SV) were recorded during prolonged LRM followed by a 500 mL fluid expansion to asses fluid responsiveness. 25 patients were screened and 18 patients analyzed. 9 patients were responders to volume expansion and 9 were not. Evaluation of hemodynamic parameters suggested the use of a linear regression model. Slopes for systolic arterial pressure, pulse pressure (PP), CVP and SV were all significantly different between responders and non-responders during the pressure increase phase of LRM (STEP-UP) (p = 0.022, p = 0.014, p = 0.006 and p = 0.038, respectively). PP and CVP slopes during STEP-UP were strongly predictive of fluid responsiveness with an AUC of 0.926 (95% CI, 0.78 to 1.00), sensitivity = 100%, specificity = 89% and an AUC = 0.901 (95% CI, 0.76 to 1.00), sensibility = 78%, specificity = 100%, respectively. Combining sensitivity of PP and specificity of CVP, prediction of fluid responsiveness can be achieved with 100% sensitivity and 100% specificity (AUC = 0.96; 95% CI, 0.90 to 1.00). One patient showed inconclusive values using the grey zone approach (5.5%).ConclusionsIn patients under mechanical ventilation with no right heart dysfunction, the association of PP and CVP slope analysis during a prolonged sigh breath LRM seems to offer a very promising method for prediction of fluid responsiveness without the use and associated cost of a cardiac output measurement device.Trial registrationNCT04304521, IRBN902018/CHUSTE. Registered 11 March 2020, Fluid responsiveness predicted by a stepwise PEEP elevation recruitment maneuver in mechanically ventilated patients (STEP-PEEP)

Effect of Stepwise Lung Recruitment Maneuver on Oxygenation, Lung Mechanics and Lung Injury Biomarkers During Lung Resection Surgery: A Prospective Randomized Controlled Single Blinded Study

ABSTRACT Background One lung ventilation for lung resection surgery may affect oxygenation, impair lung mechanics and increase the incidence of acute lung injury. Lung recruitment maneuver may improve these conditions. Settings and Design This study was a prospective randomized controlled single blinded clinical trial. Methods Forty patients scheduled for elective lung resection surgeries using one lung ventilation under general anaesthesia were randomly allocated into two groups. Control (C) group was subjected to conventional mechanical ventilation of tidal volume of 8 ml/kg and 5 ml/kg for total lung ventilation (TLV) and one lung ventilation (OLV), respectively, and PEEP of 5 cmH2O and (LR) group which was subjected to stepwise lung recruitment twice: The first lung recruitment (LR1) was performed after (OLV) to the dependent lung, while the second lung recruitment (LR2) was performed after resuming (TLV). Arterial blood gases, lung mechanics and serum tumor necrosis factor alpha were recorded at multiple time points during the study. The proposal and raw data were registered on PACTR as PACTR202001518687696. Results There was a significant decrease in PaO2/FIO2 during OLV baseline in comparison to TLV baseline (P = < 0.001*) in both groups. While, in LR group, there was a significant increase in PaO2/FIO2 and dynamic compliance during OLV-20 min after recruitment (P = <0.001*), during TLV-20 min after recruitment (P = < 0.001*) and during TLV-end (P = <0.001*). TNF-⍺ level was significantly higher in control group 1 h after surgery and 24 h postoperative. Conclusion Stepwise lung recruitment maneuver improved oxygenation parameters and lung mechanics during lung resection surgery and decreased the expression of lung injury biomarkers. Abbreviations: OLV: one lung ventilation; TLV: total lung ventilation; RM: recruitment maneuver; LR: lung recruitment; TNF-⍺: tumor necrosis factor alpha; VCV: volume controlled ventilation; PCV: pressure controlled ventilation; VT: tidal volume; FIO2: fraction of inspired oxygen; ALI: acute lung injury; ppoFEV1%: predicted postoperative forced expiratory volume in 1 s; BAL: Bronchoalveolar lavage.

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

BackgroundThe 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.MethodsThirty 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.ResultsAreas 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).ConclusionIn 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 registrationUMIN Clinical Trial Registry UMIN000027966. Registered 28th June 2017.

Comparing the Benefits of Titrated PEEP vs Low PEEP in Terms of Mortality in Patients Suffering from Acute Respiratory Distress Syndrome

Objective: To compare the benefits of titrated PEEP vs low PEEP in terms of mortality in patients suffering from acute respiratory distress syndrome&#x0D; Study Design: Randomized clinical trial&#x0D; Place and Duration of Study: Intensive care unit (ICU) of Nishtar Hospital Multan over a period of January 2017 to January 2018.&#x0D; Methodology: Patients were randomly divided into two groups LP group and TP group. TP group received fluids and neuromuscular blockers. Lung recruitment maneuver was done with incremental PEEP level and in the second time by a decremental PEEP maneuver. If levels of PaO2 and FIO2 were same or increasing during one day we stared to decrease the PEEP of 2cm Hg for every 8 hours. .&#x0D; Results: Of the outcome variables, numbers of death within 28 days were significantly higher in the low PEEP group (p-value 0.045 and 0.022, respectively). Development of pneumothorax requiring drainage and incidence of barotrauma within the first 7 days was significantly less in the titrated PEEP group. During the first 28 days, more number of patients in the titrated PEEP group had ventilator free days.&#x0D; Conclusion: In our study we find that the deaths within 28 days, development of pneumothorax requiring drainage and incidence of barotrauma within the first 7 days were significantly higher in the low PEEP group.