Alveolar Recruitment Maneuver Research Articles

Effect of the alveolar recruitment maneuver during laparoscopic colorectal surgery on postoperative pulmonary complications: A randomized controlled trial

Intraoperative lung-protective ventilation, including low tidal volume and positive end-expiratory pressure, reduces postoperative pulmonary complications. However, the effect and specific alveolar recruitment maneuver method are controversial. We investigated whether the intraoperative intermittent recruitment maneuver further reduced postoperative pulmonary complications while using a lung-protective ventilation strategy. Adult patients undergoing elective laparoscopic colorectal surgery were randomly allocated to the recruitment or control groups. Intraoperative ventilation was adjusted to maintain a tidal volume of 6–8 mL kg−1 and positive end-expiratory pressure of 5 cmH2O in both groups. The alveolar recruitment maneuver was applied at three time points (at the start and end of the pneumoperitoneum, and immediately before extubation) by maintaining a continuous pressure of 30 cmH2O for 30 s in the recruitment group. Clinical and radiological evidence of postoperative pulmonary complications was investigated within 7 days postoperatively. A total of 125 patients were included in the analysis. The overall incidence of postoperative pulmonary complications was not significantly different between the recruitment and control groups (28.1% vs. 31.1%, P = 0.711), while the mean ± standard deviation intraoperative peak inspiratory pressure was significantly lower in the recruitment group (10.7 ± 3.2 vs. 13.5 ± 3.0 cmH2O at the time of CO2 gas-out, P < 0.001; 9.8 ± 2.3 vs. 12.5 ± 3.0 cmH2O at the time of recovery, P < 0.001). The alveolar recruitment maneuver with a pressure of 30 cmH2O for 30 s did not further reduce postoperative pulmonary complications when a low tidal volume and 5 cmH2O positive end-expiratory pressure were applied to patients undergoing laparoscopic colorectal surgery and was not associated with any significant adverse events. However, the alveolar recruitment maneuver significantly reduced intraoperative peak inspiratory pressure. Further study is needed to validate the beneficial effect of the alveolar recruitment maneuver in patients at increased risk of postoperative pulmonary complications. Trial registration: Clinicaltrials.gov (NCT03681236).

Ex Vivo Porcine Experimental Model for Studying and Teaching Lung Mechanics.

Mechanical ventilation is widely used and requires specific knowledge for understanding and management. Health professionals in this field may feel insecure and lack knowledge because of inadequate training and teaching methods. Therefore, the objective of this article is to outline the steps involved in generating an ex vivo porcine lung model to be used in the future, to study and teach lung mechanics. To generate the model, five porcine lungs were carefully removed from the thorax following the guidelines of the Animal Research Ethics Committee with adequate care and were connected to the mechanical ventilator through a tracheal cannula. These lungs were then subjected to the alveolar recruitment maneuver. Respiratory mechanics parameters were recorded, and video cameras were used to obtain videos of the lungs during this process. This process was repeated for five consecutive days. When not used, the lungs were kept refrigerated. The model showed different lung mechanics after the alveolar recruitment maneuver every day; not being influenced by the days, only by the maneuver. Therefore, we conclude that the ex vivo lung model can provide a better understanding of lung mechanics and its effects, and even of the alveolar recruitment maneuver through visual feedback during all stages of the process.

The Effect of Recruitment Maneuver on Static Lung Compliance in Patients Undergoing General Anesthesia for Laparoscopic Cholecystectomy: A Single-Centre Prospective Clinical Intervention Study.

Background and Objectives: The aim of this study was to examine whether the use of an alveolar recruitment maneuver (RM) leads to a significant increase in static lung compliance (Cstat) and an improvement in gas exchange in patients undergoing laparoscopic cholecystectomy. Material and Methods: A clinical prospective intervention study was conducted. Patients were divided into two groups according to their body mass index (BMI): normal-weight (group I) and pre-obese and obese grade I (group II). Lung mechanics were monitored (Cstat, dynamic compliance-Cdin, peak pressure-Ppeak, plateau pressure-Pplat, driving pressure-DP) alongside gas exchange, and hemodynamic changes (heart rate-HR, mean arterial pressure-MAP) at six time points: T1 (induction of anesthesia), T2 (formation of pneumoperitoneum), T3 (RM with a PEEP of 5 cm H2O), T4 (RM with a PEEP of 7 cm H2O), T5 (desufflation), and T6 (RM at the end). The RM was performed by increasing the peak pressure by +5 cm of H2O at an equal inspiration-to-expiration ratio (I/E = 1:1) and applying a PEEP of 5 and 7 cm of H2O. Results: Out of 96 patients, 33 belonged to group I and 63 to group II. An increase in Cstat values occurred after all three RMs. At each time point, the Cstat value was measured higher in group I than in group II. A higher increase in Cstat was observed in group II after the second and third RM. Cstat values were higher at the end of the surgical procedure compared to values after the induction of anesthesia. The RM led to a significant increase in PaO2 in both groups without changes in HR or MAP. Conclusions: During laparoscopic cholecystectomy, the application of RM leads to a significant increase in Cstat and an improvement in gas exchange. The prevention of atelectasis during anesthesia should be initiated immediately after the induction of anesthesia, using protective mechanical ventilation and RM.

Intraoperative effects of an alveolar recruitment manoeuvre in patients undergoing laparoscopic colon surgery

IntroductionPulmonary atelectasis is common in patients undergoing laparoscopic abdominal surgery under general anaesthesia, which increases the risk of perioperative respiratory complications. Alveolar recruitment manoeuvres (ARM) are used to open up the lung parenchyma with atelectasis, although the duration of their benefit has not been clearly established. The aim of this study was to determine the effectiveness of an ARM in laparoscopic colon surgery, the duration of response over time, and its haemodynamic impact. MethodsTwenty-five patients undergoing laparoscopic colon surgery were included. After anaesthetic induction and initiation of surgery with pneumoperitoneum, an ARM was performed, and then optimal PEEP determined. Respiratory mechanics and gas exchange variables, and haemodynamic parameters, were analysed before the manoeuvre and periodically over the following 90 min. ResultsThree patients were excluded for surgical reasons. The alveolar arterial oxygen gradient went from 94.3 (62.3−117.8) mmHg before to 60.7 (29.6−91.0) mmHg after the manoeuvre (P < .05). This difference was maintained during the 90 min of the study. Dynamic compliance of the respiratory system went from 31.3 ml/cmH2O (26.1–39.2) before the manoeuvre to 46.1 ml/cmH2O (37.5−53.5) after the manoeuvre (P < .05). This difference was maintained for 60 min. No significant changes were identified in any of the haemodynamic variables studied. ConclusionIn patients undergoing laparoscopic colon surgery, performing an intraoperative ARM improves the mechanics of the respiratory system and oxygenation, without associated haemodynamic compromise. The benefit of these manoeuvres lasts for at least one hour.

Effects of a stepwise alveolar recruitment maneuver on lung volume distribution in dogs assessed by computed tomography.

Pulmonary atelectasis is a commonly occurs during anesthesia. In these cases, mechanical ventilation (MV) associated with alveolar recruitment maneuvers (ARMs) and positive end-expiratory pressure (PEEP) is indicated to reverse the condition, ensure adequate gas exchange and improve oxygenation. ARMs can trigger volutrauma, barotrauma, and atelectrauma. Therefore, computed tomography (CT) is the gold-standard method for monitoring lung aeration after ARM. To evaluate lung volume distribution after stepwise ARMs using computed tomography (CT). Twelve dogs weighing 24.0 ± 6.0 kg, aged 3 ± 1 years, of both sexes and different breeds, underwent orchiectomy or ovariohysterectomy. The animals were anesthetized and ventilated in volume-controlled mode. ARMs were then initiated by positive end-expiratory pressure (PEEP) titration (5, 10, 15, and 20 cmH2O). CT scans, cardiovascular parameters, and ventilatory mechanics were evaluated at all time points. Data were assessed for normality using the Shapiro-Wilk test and a two-way analysis of variance, followed by a post-hoc Bonferroni test to identify differences between time points. Statistical significance was attributed to a value of p of <0.05. CT demonstrated that the ARMs increased ventilation throughout the lung, including the dependent regions, with volumes that increased and decreased proportionally with PEEP titration. When they reached PEEP 10 and 5 cmH2O descending (d), they remained significantly higher than those in PEEP 0 cmH2O (baseline). Static compliance improved about 40% at PEEP 10d and PEEP 5d compared to baseline. There was an increase in heart rate (HR) from PEEP 15 increasing (i) (74.5%) to PEEP 10d (54.8%) compared to baseline. Mean arterial blood pressure (MABP) decreased approximately 9% from PEEP 15i to PEEP 15d compared to baseline. Lung attenuation and regional and global volumes assessed by CT showed that maximum pulmonary aeration distribution followed by PEEP titration occurred at PEEP 20 cmH2O, maintaining the lungs normoaerated and without hyperaeration.

Individualised, perioperative open-lung ventilation strategy during one-lung ventilation (iPROVE-OLV): a multicentre, randomised, controlled clinical trial

It is uncertain whether individualisation of the perioperative open-lung approach (OLA) to ventilation reduces postoperative pulmonary complications in patients undergoing lung resection. We compared a perioperative individualised OLA (iOLA) ventilation strategy with standard lung-protective ventilation in patients undergoing thoracic surgery with one-lung ventilation. This multicentre, randomised controlled trial enrolled patients scheduled for open or video-assisted thoracic surgery using one-lung ventilation in 25 participating hospitals in Spain, Italy, Turkey, Egypt, and Ecuador. Eligible adult patients (age ≥18 years) were randomly assigned to receive iOLA or standard lung-protective ventilation. Eligible patients (stratified by centre) were randomly assigned online by local principal investigators, with an allocation ratio of 1:1. Treatment with iOLA included an alveolar recruitment manoeuvre to 40 cm H2O of end-inspiratory pressure followed by individualised positive end-expiratory pressure (PEEP) titrated to best respiratory system compliance, and individualised postoperative respiratory support with high-flow oxygen therapy. Participants allocated to standard lung-protective ventilation received combined intraoperative 4 cm H2O of PEEP and postoperative conventional oxygen therapy. The primary outcome was a composite of severe postoperative pulmonary complications within the first 7 postoperative days, including atelectasis requiring bronchoscopy, severe respiratory failure, contralateral pneumothorax, early extubation failure (rescue with continuous positive airway pressure, non-invasive ventilation, invasive mechanical ventilation, or reintubation), acute respiratory distress syndrome, pulmonary infection, bronchopleural fistula, and pleural empyema. Due to trial setting, data obtained in the operating and postoperative rooms for routine monitoring were not blinded. At 24 h, data were acquired by an investigator blinded to group allocation. All analyses were performed on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, NCT03182062, and is complete. Between Sept 11, 2018, and June 14, 2022, we enrolled 1380 patients, of whom 1308 eligible patients (670 [434 male, 233 female, and three with missing data] assigned to iOLA and 638 [395 male, 237 female, and six with missing data] to standard lung-protective ventilation) were included in the final analysis. The proportion of patients with the composite outcome of severe postoperative pulmonary complications within the first 7 postoperative days was lower in the iOLA group compared with the standard lung-protective ventilation group (40 [6%] vs 97 [15%], relative risk 0·39 [95% CI 0·28 to 0·56]), with an absolute risk difference of -9·23 (95% CI -12·55 to -5·92). Recruitment manoeuvre-related adverse events were reported in five patients. Among patients subjected to lung resection under one-lung ventilation, iOLA was associated with a reduced risk of severe postoperative pulmonary complications when compared with conventional lung-protective ventilation. Instituto de Salud Carlos III and the European Regional Development Funds.

Change in stroke volume during alveolar recruitment maneuvers through transient continuous positive airway pressure or stepwise increase in positive end expiratory pressure in anesthetized patients: a prospective randomized double-blind study.

Intraoperative alveolar recruitment maneuvers (ARM) used during protective ventilation strategy may have severe adverse hemodynamic effects, reported mainly during abrupt continuous positive airway pressure (CPAP). Stepwise increase and decrease in positive end expiratory pressure (PEEP) may be used. We compared the hemodynamic effects of these two maneuvers. We enrolled patients scheduled for intermediate to high-risk surgery with continuous arterial pressure and stroke volume (esophageal Doppler) monitoring in a prospective, single-centre, randomized, double-blind study. After induction of anesthesia, we ensured preload independence of stroke volume before an ARM was randomly performed: 30cm H2O CPAP for 30sec (CPAP group) or stepwise increase in PEEP from 8 to 20cm H2O with inspiratory pressure of 10cm H2O followed by a stepwise decrease in PEEP from 20 to 8cm H2O (STEP group). The primary outcome was the relative variation in stroke volume. Thirty-five patients were included in the CPAP and STEP groups. Mean (standard deviation) relative variation in stroke volume was -57 (24)% in the CPAP group and -32 (24)% in the STEP group (difference, -25; 95% confidence interval, -37 to -14; P < 0.001). Changes in systolic, mean, and diastolic arterial pressure over time were not different between groups. The ARM was stopped because of a systolic arterial pressure < 70mmHg in four patients in the CPAP group and in one patient in the STEP group. Alveolar recruitment maneuvers through stepwise increase and decrease in PEEP have a better hemodynamic tolerance than transient CPAP. ClinicalTrials.gov (NCT04802421); first submitted 15 March 2021.

Evaluation of the efficiency of highly realistic simulation during the selection of ALV parameters in ARDS

The objective wasto evaluate the efficiency of the highly realistic simulator “Test Chest” in training residents in the specialty “Anesthesiology and Resus-citation” in the alveolar recruitment maneuver and the de-escalation option for setting positive end-expiratory pressure in ARDS during a practical session.Materials and methods. The study included 28 residents of the first year of study in the specialty «Anesthesiology and Resuscitation», who were divided into two groups. The 1st group – residents who were given theoretical classes before the study: lectures and a seminar on the topic: «Respiratory support in ARDS» and the 2nd group (simulation) – in addition to the lectures, the trainees had preliminary practical classes in the simulation center with a demonstration of the method of selecting ALV parameters in ARDS and independent performance of the alveolar recruit[1]ment maneuver, setting the positive pressure at the end of exhalation. In the simulation center, students were offered a situational task, the solution of which involved determining the clinical picture and selecting the necessary ALV parameters. The evaluation was carried out by two teachers independently using a checklist modified for objective student evaluation.Results. In the 1st group, 4 (28%) trainees coped with the task, in the 2nd group, in 13 cases (95%), the task was successfully completed. In the course of the study, the trainees of both groups revealed difficulties in selecting ALV parameters in ARDS, which required a more detailed consideration of these issues, both in theoretical and practical classes. Conclusion. The use of the highly realistic simulator “Test Chest” in the selection of ALV parameters in ARDS during a practical session makes it possible to increase the effectiveness of training in the alveolar recruitment maneuver and the de-escalation option for setting positive end-expiratory pressure in ARDS for residents in the specialty “Anesthesiology and resuscitation”.

Incidence, characteristics and risk factors for alveolar recruitment maneuver-related hypotension in patients undergoing laparoscopic colorectal cancer resection.

Alveolar recruitment maneuvers (ARMs) may lead to transient hypotension, but the clinical characteristics of this induced hypotension are poorly understood. We investigated the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection. To investigate the characteristics of ARM-related hypotension in patients who underwent laparoscopic colorectal cancer resection. This was a secondary analysis of the PROtective Ventilation using Open Lung approach Or Not trial and included 140 subjects. An ARM was repeated every 30 min during intraoperative mechanical ventilation. The primary endpoint was ARM-related hypotension, defined as a mean arterial pressure (MAP) < 60 mmHg during an ARM or within 5 min after an ARM. The risk factors for hypotension were identified. The peri-ARM changes in blood pressure were analyzed for the first three ARMs (ARM1,2,3) and the last ARM (ARMlast). Thirty-four subjects (24.3%) developed ARM-related hypotension. Of all 1027 ARMs, 37 (3.61%) induced hypotension. More ARMs under nonpneumoperitoneum (33/349, 9.46%) than under pneumoperitoneum conditions (4/678, 0.59%) induced hypotension (P < 0.01). The incidence of hypotension was higher at ARM1 points than at non-ARM1 points (18/135, 13.3% vs 19/892, 2.1%; P < 0.01). The median percentage decrease in the MAP at ARM1 was 14%. Age ≥ 74 years, blood loss ≥ 150 mL and peak inspiratory pressure under pneumoperitoneum < 24 cm H2O were risk factors for ARM-related hypotension. When the ARM was repeated intraoperatively, a quarter of subjects developed ARM-related hypotension, but only 3.61% of ARMs induced hypotension. ARM-related hypotension most occurred in a hemodynamically unstable state or a hypovolemic state, and in elderly subjects. Fortunately, ARMs that were performed under pneumoperitoneum conditions had less impact on blood pressure.

Diagnostic accuracy of the peripheral venous pressure variation induced by an alveolar recruitment maneuver to predict fluid responsiveness during high-risk abdominal surgery

BackgroundIn patients undergoing high-risk surgery, it is recommended to titrate fluid administration using stroke volume or a dynamic variable of fluid responsiveness (FR). However, this strategy usually requires the use of a hemodynamic monitor and/or an arterial catheter. Recently, it has been shown that variations of central venous pressure (ΔCVP) during an alveolar recruitment maneuver (ARM) can predict FR and that there is a correlation between CVP and peripheral venous pressure (PVP). This prospective study tested the hypothesis that variations of PVP (ΔPVP) induced by an ARM could predict FR.MethodsWe studied 60 consecutive patients scheduled for high-risk abdominal surgery, excluding those with preoperative cardiac arrhythmias or right ventricular dysfunction. All patients had a peripheral venous catheter, a central venous catheter and a radial arterial catheter linked to a pulse contour monitoring device. PVP was always measured via an 18-gauge catheter inserted at the antecubital fossa. Then an ARM consisting of a standardized gas insufflation to reach a plateau of 30 cmH2O for 30 s was performed before skin incision. Invasive mean arterial pressure (MAP), pulse pressure, heart rate, CVP, PVP, pulse pressure variation (PPV), and stroke volume index (SVI) were recorded before ARM (T1), at the end of ARM (T2), before volume expansion (T3), and one minute after volume expansion (T4). Receiver-operating curves (ROC) analysis with the corresponding grey zone approach were performed to assess the ability of ∆PVP (index test) to predict FR, defined as an ≥ 10% increase in SVI following the administration of a 4 ml/kg balanced crystalloid solution over 5 min.Results∆PVP during ARM predicted FR with an area under the ROC curve of 0.76 (95%CI, 0.63 to 0.86). The optimal threshold determined by the Youden Index was a ∆PVP value of 5 mmHg (95%CI, 4 to 6) with a sensitivity of 66% (95%CI, 47 to 81) and a specificity of 82% (95%CI, 63 to 94). The AUC’s for predicting FR were not different between ΔPVP, ΔCVP, and PPV.ConclusionDuring high-risk abdominal surgery, ∆PVP induced by an ARM can moderately predict FR. Nevertheless, other hemodynamic variables did not perform better.

One-Lung Ventilation and Postoperative Pulmonary Complications After Major Lung Resection Surgery. A Multicenter Randomized Controlled Trial

The effect of one-lung ventilation (OLV) strategy based on low tidal volume (TV), application of positive end-expiratory pressure (PEEP), and alveolar recruitment maneuvers (ARM) to reduce postoperative acute respiratory distress syndrome (ARDS) and pulmonary complications (PPCs) compared with higher TV without PEEP and ARM strategy in adult patients undergoing lobectomy or pneumonectomy has not been well established. Multicenter, randomized, single-blind, controlled trial. Sixteen Italian hospitals. A total of 880 patients undergoing elective major lung resection. Patients were randomized to receive lower tidal volume (LTV group: 4 mL/kg predicted body weight, PEEP of 5 cmH2O, and ARMs) or higher tidal volume (HTL group: 6 mL/kg predicted body weight, no PEEP, and no ARMs). After OLV, until extubation, both groups were ventilated using a tidal volume of 8 mL/kg and a PEEP value of 5 cmH2O. The primary outcome was the incidence of in-hospital ARDS. Secondary outcomes were the in-hospital rate of PPCs, major cardiovascular events, unplanned intensive care unit (ICU) admission, in-hospital mortality, ICU length of stay, and in-hospital length of stay. ARDS occurred in 3 of 438 patients (0.7%, 95% CI 0.1-2.0) and in 1 of 442 patients (0.2%, 95% CI 0-1.4) in the LTV and HTV group, respectively (Risk ratio: 3.03 95% CI 0.32-29, p=0.372). Pulmonary complications occurred in 125 of 438 patients (28.5%, 95% CI 24.5-32.9) and in 136 of 442 patients (30.8%, 95% CI 26.6-35.2) in the LTV and HTV group, respectively (risk ratio: 0.93, 95% CI 0.76-1.14, p=0.507). The incidence of major complications, in-hospital mortality, and unplanned ICU admission, ICU and in-hospital length of stay were comparable in both groups. In conclusion, among adult patients undergoing elective lung resection, an OLV with lower tidal volume, PEEP 5 cmH2O, and ARMs and a higher tidal volume strategy resulted in low ARDS incidence and comparable postoperative complications, in-hospital length of stay, and mortality.

Flow-controlled expiration reduces positive end-expiratory pressure requirement in dorsally recumbent, anesthetized horses.

Equine peri-anesthetic mortality is higher than that for other commonly anesthetized veterinary species. Unique equine pulmonary pathophysiologic aspects are believed to contribute to this mortality due to impairment of gas exchange and subsequent hypoxemia. No consistently reliable solution for the treatment of peri-anesthetic gas exchange impairment is available. Flow-controlled expiration (FLEX) is a ventilatory mode that linearizes gas flow throughout the expiratory phase, reducing the rate of lung emptying and alveolar collapse. FLEX has been shown to improve gas exchange and pulmonary mechanics in anesthetized horses. This study further evaluated FLEX ventilation in anesthetized horses positioned in dorsal recumbency, hypothesizing that after alveolar recruitment, horses ventilated using FLEX would require a lower positive end-expiratory pressure (PEEP) to prevent alveolar closure than horses conventionally ventilated. Twelve adult horses were used in this prospective, randomized study. Horses were assigned either to conventional volume-controlled ventilation (VCV) or to FLEX. Following induction of general anesthesia, horses were placed in dorsal recumbency mechanically ventilated for a total of approximately 6.5 hours. Thirty-minutes after starting ventilation with VCV or FLEX, a PEEP-titration alveolar recruitment maneuver was performed at the end of which the PEEP was reduced in decrements of 3 cmH2O until the alveolar closure pressure was determined. The PEEP was then increased to the previous level and maintained for additional three hours. During this time, the mean arterial blood pressure, pulmonary arterial pressure, central venous blood pressure, cardiac output (CO), dynamic respiratory system compliance and arterial blood gas values were measured. The alveolar closure pressure was significantly lower (6.5 ± 1.2 vs 11.0 ± 1.5 cmH2O) and significantly less PEEP was required to prevent alveolar closure (9.5 ± 1.2 vs 14.0 ± 1.5 cmH2O) for horses ventilated using FLEX compared with VCV. The CO was significantly higher in the horses ventilated with FLEX (37.5 ± 4 vs 30 ± 6 l/min). We concluded that FLEX ventilation was associated with a lower PEEP requirement due to a more homogenous distribution of ventilation in the lungs during expiration. This lower PEEP requirement led to more stable and improved cardiovascular conditions in horses ventilated with FLEX.

Prediction of hypotension during the alveolar recruitment maneuver in spine surgery: a prospective observational study

BackgroundAtelectasis can occur in many clinical practices. One way to prevent this complication is through the alveolar recruitment maneuver (ARM). However, hemodynamic compromise can accompany ARM. This study aims to predict ARM-induced hypotension using a non-invasive method.Methods94 American Society of Anesthesiologists physical status I–II patients aged 19 to 75 with scheduled spinal surgery were enrolled. After anesthesia, we performed a stepwise ARM. Data on perfusion index, mean arterial pressure, heart rate, pleth variability index, cardiac index, and stroke volume variation was collected before induction of anesthesia (T0), just before ARM (T1), at the start of ARM (T2), 0.5 min (T3), 1 min (T4), 1.5 min (T5, end of ARM), and 2 min after the beginning of ARM (T6). Hypotension was defined as when the mean arterial pressure at T5 decreased by 20% or more compared to the baseline. The primary endpoint is that the perfusion index measuring before induction of anesthesia, which reflects the patients’ own vascular tone, was correlated with hypotension during ARM.ResultsSeventy-five patients (79.8%) patients developed hypotension during ARM. The pre-induction persufion index (Pi) (95% confidence interval) was 1.7(1.4–3.1) in the non-hypotension group and 3.4(2.4–3.9) in the hypotension group. (p < 0.004) The hypotension group showed considerably higher Pi than the non-hypotension group before induction. The decrease of Pi (%) [IQR] in the non-hypotensive group (52.8% [33.3–74.7]) was more significant than in the hypotensive group. (36% [17.6–53.7]) (p < 0.05) The area under the receiver operating characteristic curve of Pi for predicting hypotension during ARM was 0.718 (95% CI 0.615–0.806; p = 0.004), and the threshold value of the Pi was 2.4.ConclusionA higher perfusion index value measuring before induction of anesthesia can be used to predict the development of hypotension during ARM. Prophylactic management of the following hypotension during ARM could be considered in high baseline Pi patients.

The respiratory and hemodynamic effects of alveolar recruitment in cirrhotic patients undergoing liver resection surgery: A randomized controlled trial.

Extensive surgical retraction combined with general anesthesia increase alveolar collapse. The primary aim of our study was to investigate the effect of alveolar recruitment maneuver (ARM) on arterial oxygenation tension (PaO2). The secondary aim was to observe its effect on hemodynamics parameters in hepatic patients during liver resection, to investigate its impact on blood loss, postoperative pulmonary complications (PPC), remnant liver function tests, and on the outcome. Adult patients scheduled for liver resection were randomized into two groups: ARM (n = 21) and control (C) (n = 21). Stepwise ARM was initiated after intubation and was repeated post-retraction. Pressure-control ventilation mode was adjusted to deliver a tidal volume (Vt) of 6 mL/kg and an inspiratory-to-expiratory time (I:E) ratio of 1:2 with an optimal positive end-expiratory pressure (PEEP) for the ARM group. In the C group, a fixed PEEP (5 cmH2O) was applied. Invasive intra-arterial blood pressure (IBP), central venous pressure (CVP), electrical cardiometry (EC), alanine transaminase (ALT, U/L), and aspartate aminotransferase (AST, U/L) blood levels were monitored. ARM increased PEEP, dynamic compliances, and arterial oxygenation, but reduced ventilator driving pressure compared to group C (P < 0.01). IBP, cardiac output (CO), and stroke volume variation were not affected by the higher PEEP in the ARM group (P > 0.05) but the CVP increased significantly (P = 0.001). Blood loss was not different between the ARM and C groups (1700 (1150-2000) mL vs 1110 (900-2400) mL, respectively and P = 0.57). ARM reduced postoperative oxygen desaturation; however, it did not affect the increase in remnant liver enzymes and was comparable to group C (ALT, P = 0.54, AST, P = 0.41). ARM improved intraoperative lung mechanics and reduced oxygen desaturation episodes in recovery, but not PPC or ICU stay. ARM was tolerated with minimal cardiac and systemic hemodynamic effects.

Effect of the alveolar recruitment manoeuvre on pulmonary complications in the immediate postoperative period of cardiac surgery

Introdução: dada a grande variabilidade nos protocolos de ventilação, manejo pós-operatório, características da manobra de recrutamento alveolar (MRA) (frequência, duração e intensidade) e tolerabilidade em pacientes submetidos à cirurgia cardíaca (CC), este estudo investiga se a MRA é benéfica nesta área, a fim de padronizar seu uso. Objetivo: investigou-se a eficácia da MRA contra complicações pulmonares (CPs) imediatamente após a CC. Metodologia: este ensaio clínico randomizado incluiu 134 pacientes com idade &gt; 18 anos submetidos à cirurgia de revascularização do miocárdio ou cirurgia de substituição valvar em nossa instituição entre fevereiro e setembro de 2019. Os participantes foram alocados para receber fisioterapia padrão (grupo controle [GC], n=67) ou fisioterapia padrão com adição da MRA (grupo intervenção [GI], n=67). Resultados: não houve diferença estatisticamente significativa na incidência de CPs entre os grupos GC e GI (p=0,85). A MRA não melhorou as trocas gasosas ou reduziu o tempo total de ventilação mecânica, necessidade de reintubação na unidade de terapia intensiva e internação hospitalar. Conclusão: a MRA profilática não diminui a incidência de CPs no pós-operatório de CC, não melhora as trocas gasosas, nem reduziu o tempo de VM. A MRA foi associada a um risco aumentado de instabilidade hemodinâmica. Os pacientes devem ser avaliados antes de realizar MRA

The optimal PEEP after alveolar recruitment maneuver assessed by electrical impedance tomography in healthy horses.

Electrical impedance tomography (EIT) has been an essential tool for assessing pulmonary ventilation in several situations, such as the alveolar recruitment maneuver (ARM) in PEEP titration to maintain the lungs open after atelectasis reversion. In the same way as in humans and dogs, in horses, this tool has been widely used to assess pulmonary aeration undergoing anesthesia, mechanical ventilation, recruitment maneuver, standing horses, or specific procedures. The present study aimed to evaluate the distribution of regional ventilation during ARM based on lung monitoring assessment by EIT, with a focus on better recruitment associated with less or no overdistention. Fourteen horses of 306 ± 21 kg undergoing isoflurane anesthesia in dorsal recumbency were used. The animals were mechanically ventilated with a tidal volume of 14 ml kg-1 and a respiratory rate of 7-9. An alveolar recruitment maneuver was instituted, increasing the PEEP by five cmH2O every 5 min until 32 cmH2O and decreasing it by five cmH2O every 5 min to 7 cmH2O. At each step of PEEP, arterial blood samples were collected for blood gas analysis, EIT images, hemodynamic, and respiratory mechanics. Associated with the CoV-DV increase, there was a significant decrease in the DSS during the ARM and a significant increase in the NSS when PEEP was applied above 12 cmH2O compared to baseline. The ComplROI showed a significant increase in the dependent area and a significant decrease in the non-dependent area during ARM, and both were compared to their baseline values. The driving pressure decreased significantly during the ARM, and Cst, PaO2, and PaO2/FiO2 ratio increased significantly. The VD/VT decreased significantly at DEPEEP17 and DEPEEP12. There was an HR increase at INPEEP27, INPEEP 32, and DEPEEP17 (p < 0.0001; p < 0.0001; and p < 0.05, respectively), those values being above the normal reference range for the species. The SAP, MAP, DAP, CI, and DO2I significantly decreased INPEEP32 (p < 0.05). The ARM by PEEP titration applied in the present study showed better ventilation distribution associated with better aeration in the dependent lung areas, with minimal overdistention between PEEP 17 and 12 cmH2O decreasing step. Those changes were also followed by improvements in static and regional compliance associated with increased oxygenation and pulmonary ventilation. ARM promoted a transitory decrease in arterial blood pressure and depression in CI with a concomitant drop in oxygen delivery, which should be best investigated before its routine use in clinical cases.

Efficacy of recruitment manoeuvre with or without antiderecruitment strategy in ARDS patients: A prospective study

Introduction: Lung recruitment manoeuvre (RM) opens up collapsed segments of the ARDS lung but the collapse may reappear once the RM is complete and pre-RM positive end-expiratory pressure (PEEP) is applied. Aim: Evaluation of the outcome of setting PEEP using decrement PEEP titration (antiderecruitment manoeuvre - ADRM) after an alveolar recruitment manoeuvre (RM) in ARDS patients. Methods: Twenty four mechanically ventilated adult patients with ARDS were enrolled. This was a randomised, prospective study. After recording baseline parameters, on pressure control ventilation and stabilisation, RM was performed. The responders were randomly assigned to one of two groups: ‘Antiderecruitment RM’ (ADRM) group and ‘Only RM’ (RM) group. ADRM group received RM using volume control ventilation and optimal PEEP was set after RM using decremental PEEP titration method. The RM group patients were returned to baseline ventilator settings after manoeuvre. Results: Of the 24 patients, 13 were males and 11 female. The mean (± SD) age was 43 (± 13.43) years. Twelve patients responded to the initial recruitment manoeuvre of which six were assigned to RM group and six to ADRM group. There was no difference in survival rate between the groups. The ICU and hospital stay were shorter in patients in ADRM group as compared to only RM group. Conclusion: Only half of the patients with ARDS respond to recruitment manoeuvres with an improvement in oxygenation. In most responders, the improvement is sustained irrespective of whether RM only or ADRM was used. Mortality is high if the baseline P/F ratio is below 90.

Impact of positive end-expiratory pressure with alveolar recruitment maneuver on respiratory and oxygenation parameters of patients during laparoscopic bariatric surgery.

Laparoscopic bariatric surgery is frequently associated with disturbances in respiratory mechanics. An alveolar recruitment maneuver (ARM) with positive end-expiratory pressure (PEEP) is a strategy to overcome such respiratory conditions. This study aimed to evaluate the effect of ARM+PEEP on intraoperative and postoperative respiratory and hemodynamic parameters of patients with laparoscopic bariatric surgery. Patients who underwent laparoscopic bariatric surgery between 2009 and 2016 were retrospectively evaluated. The study sample was divided into four groups based on PEEP values and the presence of ARM: Group PEEP 5 (5 cm H2O PEEP only), Group PEEP 5/RM (5 cm H2O PEEP plus ARM), Group PEEP 10 (10 cm H2O PEEP only), Group PEEP 10/RM (10 cm H2O PEEP plus ARM). Patients' demographic characteristics, ventilatory, respiratory, and oxygenation parameters were recorded. Oxygenation index (PaO2/FiO2) was the study's primary outcome. There were 156, 158, 299, and 210 patients in Groups PEEP 5, PEEF 5/RM, PEEP 10, and PEEP 10/RM, respectively. Tidal volume, driving tidal volume/compliance, PaO2, PaO2/FiO2, and PaCO2 were significantly lower in Groups PEEP 5 and PEEP 5/RM, whereas SpO2 and FiO2 were significantly higher in Groups PEEP 5 and PEEP 5/RM (p<0.05). Patients in Group PEEP 5 had significantly higher end-tidal carbon dioxide (EtCO2) values than those of other groups (p<0.001). Patients in Group PEEP 5/RM had significantly higher SpO2 values than those in Group PEEP 5 (p<0.001). Rate of postoperative atelectasis was significantly higher in Group PEEP 5/RM compared to the other groups (p=0.011). A PEEP level of at least 10 cm H2O with ARM improved intraoperative respiratory parameters and caused a significant reduction in postoperative atelectasis.

Update on the use of ultrasound in the diagnosis and monitoring of the critical patient.

Hemodynamic and respiratory complications are the main causes of morbidity and mortality in in critical care units (CCU). Imaging techniques are a key tool in differential diagnosis and treatment. In the last decade, ultrasound has shown great potential for bedside diagnosis of respiratory disease, as well as for the hemodynamic assessment of critically ill patients. Ultrasound has proven to be a useful guide for identifying the type of shock, estimating cardiac output, guiding fluid therapy and vasoactive drugs, providing security in the performance of percutaneous techniques (thoracentesis, pericardiocentesis, evacuation of abscesses/hematomas), detecting dynamically in real time pulmonary atelectasis and its response to alveolar recruitment maneuvers, and predicting weaning failure from mechanical ventilation. Due to its dynamic nature, simple learning curve and absence of ionizing radiation, it has been incorporated as an essential tool in daily clinical practice in CCUs. The objective of this review is to offer a global vision of the role of ultrasound and its applications in the critically ill patient.

COVID-19 knowledge, attitudes, and practices among health care workers in Latin America.

To evaluate COVID-19 knowledge, attitudes, and practices among health care workers (HCWs) practicing in Latin American countries during the first surge of the COVID-19 pandemic. This was a multinational cross-sectional survey study, using an online self-administered questionnaire. The final version of the questionnaire comprised 40 questions, organized in five sections: demographic and professional characteristics; COVID-19 knowledge; attitudes toward COVID-19; COVID-19 practices; and institutional resources. The study involved 251 HCWs from 19 Latin American countries who agreed to participate. In our sample, 77% of HCWs participated in some sort of institutional training on COVID-19, and 43% had a low COVID-19 knowledge score. COVID-19 knowledge was associated with the type of health center (public/private), availability of institutional training, and sources of information about COVID-19. Concerns about not providing adequate care were reported by 60% of the participants. The most commonly used ventilatory strategies were protective mechanical ventilation, alveolar recruitment maneuvers, and prone positioning, and the use of drugs to treat COVID-19 was mainly based on institutional protocols. In this multinational study in Latin America, almost half of HCWs had a low COVID-19 knowledge score, and the level of knowledge was associated with the type of institution, participation in institutional training, and information sources. HCWs considered that COVID-19 was very relevant, and more than half were concerned about not providing adequate care to patients.