Recruitment Maneuvers Research Articles

Utility of lung ultrasound in adjustment of the initial mechanical ventilation settings in patients with acute respiratory distress syndrome

Background Bedside lung ultrasound (US) is an essential tool in assessing lung aeration in severely ill patients. Aim The goal of this study was to determine the use of lung US in evaluating changes in lung aeration in dependent lung areas during positive end expiratory pressure (PEEP) titration in patients with acute respiratory distress syndrome (ARDS). Patients and methods A total of 52 mechanically ventilated patients with ARDS admitted in the ICU of Abbassia Chest Hospital were enrolled in this study. Transthoracic sonography was performed at the posterior axillary line on either side after 30 min of initial ventilator settings; recruitment at the end of expiration was sonographically assessed while changing PEEP. Arterial blood gases were performed before and after recruitment maneuver along with continuous monitoring of hemodynamics and oxygen saturation throughout the procedure. The procedure was terminated if the plateau pressure exceeded 30 cmH2O or if there was hemodynamic compromise. Results A total of 52 mechanically ventilated patients with ARDS were enrolled in the study. Overall, 80% had severe ARDS. Initial US assessments were done, and subpleural consolidation (C) was found in 18 patients, whereas exaggerated B lines (B) were found in 33 patients. After PEEP titration, under US guidance, 13 patients changed the US pattern from C to B and 22 patients changed from B to A (A-line pattern). These results correlated with improvement of PaO2/FiO2 ratio from 69.98 ± 27.93 to 86.21 ± 31.64 and increased compliance from 26.49 ± 8.63 to 28.73 ± 8.74. However, there was an increase in plateau pressure from 25.12 ± 3.88 to 27.98 ± 3.18, and also PaCO2 increased from 51.00 ± 16.05 to 58.52 ± 15.93. The mean arterial blood pressure decreased from 84.87 ± 7.91 to 81.60 ± 8.72. Conclusion US is an effective tool in achieving PEEP titration in mechanically ventilated patients with ARDS. US finding of aeration correlates well with improvement in oxygenation and compliance. However, the patients should be monitored for safe limits of pressures, hemodynamics, and PaCO2 level that may rise.

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 > 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

Lung Injury Is Induced by Abrupt Increase in Respiratory Rate but Prevented by Recruitment Maneuver in Mild Acute Respiratory Distress Syndrome in Rats.

Gradually changing respiratory rate (RR) during time to reduce ventilation-induced lung injury has not been investigated. The authors hypothesized that gradual, compared with abrupt, increments in RR would mitigate ventilation-induced lung injury and that recruitment maneuver before abruptly increasing RR may prevent injurious biologic impact. Twenty-four hours after intratracheal administration of Escherichia coli lipopolysaccharide, 49 male Wistar rats were anesthetized and mechanically ventilated (tidal volume, 6 ml/kg; positive end-expiratory pressure, 3 cm H2O) with RR increase patterns as follows (n = 7 per group): (1) control 1, RR = 70 breaths/min for 2 h; (2) and (3) abrupt increases of RR for 1 and 2 h, respectively, both for 2 h; (4) shorter RR adaptation, gradually increasing RR (from 70 to 130 breaths/min during 30 min); (5) longer RR adaptation, more gradual increase in RR (from 70 to 130 breaths/min during 60 min), both for 2 h; (6) control 2, abrupt increase of RR maintained for 1 h; and (7) control 3, recruitment maneuver (continuous positive airway pressure, 30 cm H2O for 30 s) followed by control-2 protocol. At the end of 1 h of mechanical ventilation, cumulative diffuse alveolar damage scores were lower in shorter (11.0 [8.0 to 12.0]) and longer (13.0 [11.0 to 14.0]) RR adaptation groups than in animals with abrupt increase of RR for 1 h (25.0 [22.0 to 26.0], P = 0.035 and P = 0.048, respectively) and 2 h (35.0 [32.0 to 39.0], P = 0.003 and P = 0.040, respectively); mechanical power and lung heterogeneity were lower, and alveolar integrity was higher, in the longer RR adaptation group compared with abruptly adjusted groups; markers of lung inflammation (interleukin-6), epithelial (club cell secretory protein [CC-16]) and endothelial cell damage (vascular cell adhesion molecule 1 [VCAM-1]) were higher in both abrupt groups, but not in either RR adaptation group, compared with controls. Recruitment maneuver prevented the increase in VCAM-1 and CC-16 gene expressions in the abruptly increased RR groups. In mild experimental acute respiratory distress syndrome in rats, gradually increasing RR, compared with abruptly doing so, can mitigate the development of ventilation-induced lung injury. In addition, recruitment maneuver prevented the injurious biologic impact of abrupt increases in RR.

The importance of lung recruitability: A novel ultrasound pattern to guide lung recruitment in neonates.

Lung Ultrasound (LUS)-guided Lung Recruitment Maneuver (LRM) has been shown to possibly reduce ventilator-induced lung injury in preterm infants. However, to avoid potential hemodynamic and pulmonary side effects, the indication to perform the maneuver needs to be supported by early signs of lung recruitability. Recently, a new LUS pattern (S-pattern), obtained during the reopening of collapsed parenchyma, has been described. This study aims to evaluate if this novel LUS pattern is associated with a higher clinical impact of the LUS-guided LRMs. All the LUS-guided rescue LRMs performed on infants with oxygen saturation/fraction of inspired oxygen (S/F) ratio below 200, were included in this cohort study. The primary outcome was to determine if the presence of the S-pattern is associated with the success of LUS-guided recruitment, in terms of the difference between the final and initial S/F ratio (Delta S/F). We reported twenty-two LUS-guided recruitments, performed in nine patients with a median gestational age of 34 weeks, interquartile range (IQR) 28-35 weeks. The S-pattern could be obtained in 14 recruitments (64%) and appeared early during the procedure, after a median of 2 cmH2O (IQR 1-3) pressure increase. The presence of the S-pattern was significantly associated with the effectiveness of the maneuver as opposed to the cases in which the S-pattern could not be obtained (Delta S/F 110 +/- 47 vs 44 +/- 39, p = 0.01). Our results suggest that the presence of the S-pattern may be an early sign of lung recruitability, predicting LUS-guided recruitment appropriateness and efficacy.

Regular lung recruitment maneuvers during high-frequency oscillatory ventilation in extremely preterm infants: a randomized controlled trial

BackgroundLung recruitment maneuvers (LRMs) improve lung volume at initiation of high-frequency oscillatory ventilation (HFOV), but it is unclear when to repeat LRMs. We evaluated the efficiency of scheduled LRMs.MethodsIn a randomized controlled trial, extremely preterm infants on HFOV received either LRMs at 12-hour intervals and when clinically indicated (intervention) or only when clinically indicated (control). The primary outcome was the cumulative oxygen saturation index (OSI) over HFOV time, limited to 7 days. Additionally, LRMs were analyzed with respect to OSI improvement.ResultsFifteen infants were included in each group. The mean (SD) postmenstrual age and weight at HFOV start were 23 + 6 (0 + 5) weeks and 650 (115) g in the intervention group and 24 + 4 (0 + 6) weeks (p = 0.03) and 615 (95) g (p = 0.38) in the control group. The mean (SD) cumulative OSI amounted to 4.95 (1.72) in the intervention versus 5.30 (2.08) in the control group (p = 0.61). The mean (SD) number of LRMs in 12 h was 1.3 (0.2) in the intervention versus 1.1 (0.5) in the control group (p = 0.13). Performing LRM when FiO2 > 0.6 resulted in a mean OSI reduction of 3.6.ConclusionRegular versus clinically indicated LRMs were performed with equal frequency in preterm infants during HFOV, and consequently, no difference in lung volume was observed. LRMs seem to be most efficient at high FiO2.Trial registrationClinicalTrials.gov ID: NCT04289324 (28/02/2020).

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.

Lung-protective ventilation during Trendelenburg pneumoperitoneum surgery: A randomized clinical trial

Study objectiveTo assess the effects of a protective ventilation strategy during Trendelenburg pneumoperitoneum surgery on postoperative oxygenation. DesignsParallel-group, randomized trial. SettingOperating room of a university hospital, Italy. PatientsMorbidly obese patients undergoing Trendelenburg pneumoperitoneum gynaecological surgery. InterventionsParticipants were randomized to standard (SV: tidal volume = 10 ml/kg of predicted body weight, PEEP = 5 cmH2O) or protective (PV: tidal volume = 6 ml/kg of predicted body weight, PEEP = 10 cmH2O, recruitment maneuvers) ventilation during anesthesia. MeasurementsPrimary outcome was PaO2/FiO2 one hour after extubation. Secondary outcomes included day-1 PaO2/FiO2, day-2 respiratory function and intraoperative respiratory/lung mechanics, assessed through esophageal manometry, end-expiratory lung volume (EELV) measurement and pressure-volume curves. Main resultsSixty patients were analyzed (31 in SV group, 29 in PV group). Median [IqR] tidal volume was 350 ml [300–360] in PV group and 525 [500–575] in SV group. Median PaO2/FiO2 one hour after extubation was 280 mmHg [246–364] in PV group vs. 298 [250–343] in SV group (p = 0.64). Day-1 PaO2/FiO2, day-2 forced vital capacity, FEV-1 and Tiffenau Index were not different between groups (all p > 0.10). Intraoperatively, 59% of patients showed complete airway closure during pneumoperitoneum, without difference between groups: median airway opening pressure was 17 cmH2O. In PV group, airway and transpulmonary driving pressure were lower (12 ± 5 cmH2O vs. 17 ± 7, p < 0.001; 9 ± 4 vs. 13 ± 7, p < 0.001), PaCO2 and respiratory rate were higher (48 ± 8 mmHg vs. 42 ± 12, p < 0.001; 23 ± 5 breaths/min vs. 16 ± 4, p < 0.001). Intraoperative EELV was similar between PV and SV group (1193 ± 258 ml vs. 1207 ± 368, p = 0.80); ratio of tidal volume to EELV was lower in PV group (0.45 ± 0.12 vs. 0.32 ± 0.09, p < 0.001). ConclusionsIn obese patients undergoing Trendelenburg pneumoperitoneum surgery, PV did not improve postoperative oxygenation nor day-2 respiratory function. PV was associated with intraoperative respiratory mechanics indicating less injurious ventilation. The high prevalence of complete airway closure may have affected study results. Trial registrationProspectively registered on http://clinicaltrials.govNCT03157479 on May 17th, 2017.

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.

Year in Review 2015: Recruitment manoeuvres in ARDS

Refractory hypoxaemia is a problem in patients with acute respiratory distress syndrome (ARDS). Although mechanical ventilation is the mainstay of management of ARDS, this therapy itself can cause damage to the lungs due to high tidal volume and high airway pressures. Lung protective strategies are used to reduce damage to the lungs due to mechanical ventilation. Use of small tidal volumes can cause alveolar derecruitment and arterial hypoxaemia. Lung recruitment manoeuvre (RM) opens up collapsed segments of the ARDS lung but the collapse may reappear once the RM is complete. Although RM has been shown to improve oxygenation there is still no clear data showing improvement in clinical outcome. This review summarises the different techniques used for RM, physiological effects of RM on lung mechanics along with monitoring RM at the bedside.

Respiratory function under anaesthesia

General anaesthesia can affect every aspect of ventilation. It produces dose dependent depression of control of respiration. Carbon dioxide response curve is shifted to the right. Muscle tone is reduced and the airway can get obstructed. One of the most prominent changes is reduction in functional residual capacity (FRC) with the adoption of supine function and induction of anaesthesia. The closing capacity increases with age. The atelectasis that occurs consequent to the fall in FRC and increasing age is compounded by the use of high concentrations of oxygen, cephalad movement of the diaphragm, residual effect of muscle relaxants and inadequate analgesia after thoracic or abdominal surgery. One of the important causes of ventilation perfusion mismatch during anaesthesia is atelectasis. This has been shown to contribute to hypoxia as well as increased postoperative pulmonary complications. A lot of research is being conducted as to reduce the effects of atelectasis during anaesthesia, including the best ventilator strategy during anaesthesia. Most inhalation anaesthetics are good bronchodilators. Inhalation anaesthetics depress hypoxic pulmonary vasoconstriction (HPV) beyond 1 MAC. The movement of ciliary movements is reduced with the use of dry gases. All these can increase postoperative pulmonary complications which are important causes of postoperative morbidity. Appropriate preoperative preparation has to be combined with optimal management of ventilation intraoperatively to minimise postoperative pulmonary complications. The role of lower tidal volume, use of positive end-expiratory pressure, limiting oxygen concentrations and the utility of recruitment manoeuvres are increasingly being recognised and have been the topics of recent research.

Inspiratory and end-expiratory effects of lung recruitment in the prone position on dorsal lung aeration - new physiological insights in a secondary analysis of a randomised controlled study in post-cardiac surgery patients.

Cardiac surgery produces dorso-basal atelectasis and ventilation/perfusion mismatch, associated with infection and prolonged intensive care. A postoperative lung volume recruitment manoeuvre to decrease the degree of atelectasis is routine. In patients with severe respiratory failure, prone positioning and recruitment manoeuvres may increase survival, oxygenation, or both. We compared the effects of lung recruitment in prone vs supine positions on dorsal inspiratory and end-expiratory lung aeration. In a prospective RCT, 30 post-cardiac surgery patients were randomly allocated to recruitment manoeuvres in the prone (n=15) or supine position (n=15). The primary endpoints were late dorsal inspiratory volume (arbitrary units [a.u.]) and left/right dorsal end-expiratory lung volume change (a.u.), prone vs supine after extubation, measured using electrical impedance tomography. Secondary outcomes included left/right dorsal inspiratory volumes (a.u.) and left/right dorsal end-expiratory lung volume change (a.u.) after prone recruitment and extubation. The last part of dorsal end-inspiratory volume after extubation was higher after prone (49.1 a.u.; 95% confidence interval [CI], 37.4-60.6) vs supine recruitment (24.2 a.u.; 95% CI, 18.4-29.6; P=0.024). Improvement in left dorsal end-expiratory lung volume after extubation was higher after prone (382 a.u.; 95% CI, 261-502) vs supine recruitment (-71 a.u., 95% CI, -140 to -2; n=15; P<0.001). After prone recruitment, left vs right predominant end-expiratory dorsal lung volume change disappeared after extubation. However, both left and right end-expiratory volumes were higher in the prone group, after extubation. Recruitment in the prone position improves dorsal inspiratory and end-expiratory lung volumes after cardiac surgery. NCT03009331.

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.

Latent class analysis of imaging and clinical respiratory parameters from patients with COVID-19-related ARDS identifies recruitment subphenotypes

BackgroundPatients with COVID-19-related acute respiratory distress syndrome (ARDS) require respiratory support with invasive mechanical ventilation and show varying responses to recruitment manoeuvres. In patients with ARDS not related to COVID-19, two pulmonary subphenotypes that differed in recruitability were identified using latent class analysis (LCA) of imaging and clinical respiratory parameters. We aimed to evaluate if similar subphenotypes are present in patients with COVID-19-related ARDS.MethodsThis is the retrospective analysis of mechanically ventilated patients with COVID-19-related ARDS who underwent CT scans at positive end-expiratory pressure of 10 cmH2O and after a recruitment manoeuvre at 20 cmH2O. LCA was applied to quantitative CT-derived parameters, clinical respiratory parameters, blood gas analysis and routine laboratory values before recruitment to identify subphenotypes.Results99 patients were included. Using 12 variables, a two-class LCA model was identified as best fitting. Subphenotype 2 (recruitable) was characterized by a lower PaO2/FiO2, lower normally aerated lung volume and lower compliance as opposed to a higher non-aerated lung mass and higher mechanical power when compared to subphenotype 1 (non-recruitable). Patients with subphenotype 2 had more decrease in non-aerated lung mass in response to a standardized recruitment manoeuvre (p = 0.024) and were mechanically ventilated longer until successful extubation (adjusted SHR 0.46, 95% CI 0.23–0.91, p = 0.026), while no difference in survival was found (p = 0.814).ConclusionsA recruitable and non-recruitable subphenotype were identified in patients with COVID-19-related ARDS. These findings are in line with previous studies in non-COVID-19-related ARDS and suggest that a combination of imaging and clinical respiratory parameters could facilitate the identification of recruitable lungs before the manoeuvre.

Shortened Automatic Lung Recruitment Maneuvers in an In Vivo Model of Neonatal ARDS.

The aim of this study was to assess the safety and efficacy of 2 protocols for automatic lung recruitment maneuvers (LRMs) using stepwise increases in PEEP in a neonatal ARDS model. These protocols were designed with lower maximum opening pressures than traditional methods and differ each one in the duration of the opening phases (short vs prolonged). We described hemodynamic changes through invasive monitoring, and we analyzed if the behavior of the variables depends on the duration of the opening phase of the LRM. We designed a prospective, experimental study with 10 Landrace x Large White pigs < 48 h old. Under general anesthesia, tracheal intubation, invasive hemodynamic monitoring with a pediatric arterial thermodilution catheter was performed. An ARDS model was developed with bronchoalveolar lavages. Two types of LRMs were performed in each piglet, with a maximum peak inspiratory pressure (PIP) of 30 cm H2O and a PEEP 15 cm H2O applied during 8.5 s in the short LRM and 17 s in the prolonged LRM. A comparative analysis by virtue of the Wilcoxon signed-rank test and a regression analysis using generalized estimation equation were performed. We found that both LRMs were effective regarding oxygenation and respiratory mechanics. Shortening the duration of the opening phase and lowering the maximum opening pressures to PIP 30 and PEEP 15 cm H2O were above the critical opening pressure to reverse alveolar collapse in our neonatal ARDS model. Although we observed hemodynamic variations during both types of LRMs, these were well tolerated. Our LRM protocols exceeded critical opening pressures to reverse alveolar collapse in our neonatal ARDS model. This range of pressures might involve less hemodynamic disturbance. Duration of the maximum opening pressure step is a determining factor for hemodynamic alterations.

Correlation between the hysteresis of the pressure–volume curve and the recruitment-to-inflation ratio in patients with coronavirus disease 2019

BackgroundSince the response to lung recruitment varies greatly among patients receiving mechanical ventilation, lung recruitability should be assessed before recruitment maneuvers. The pressure–volume curve (PV curve) and recruitment-to-inflation ratio (R/I ratio) can be used bedside for evaluating lung recruitability and individualing positive end-expiratory pressure (PEEP). Lung tissue recruitment on computed tomography has been correlated with normalized maximal distance (NMD) of the quasi-static PV curve. NMD is the maximal distance between the inspiratory and expiratory limb of the PV curve normalized to the maximal volume. However, the relationship between the different parameters of hysteresis of the quasi-static PV curve and R/I ratio for recruitability is unknown.MethodsWe analyzed the data of 33 patients with severe coronavirus disease 2019 (COVID-19) who received invasive mechanical ventilation. Respiratory waveform data were collected from the ventilator using proprietary acquisition software. We examined the relationship of the R/I ratio, quasi-static PV curve items such as NMD, and respiratory system compliance (Crs).ResultsThe median R/I ratio was 0.90 [interquartile range (IQR), 0.70–1.15] and median NMD was 41.0 [IQR, 37.1–44.1]. The NMD correlated significantly with the R/I ratio (rho = 0.74, P < 0.001). Sub-analysis showed that the NMD and R/I ratio did not correlate with Crs at lower PEEP (− 0.057, P = 0.75; and rho = 0.15, P = 0.41, respectively). On the contrary, the ratio of Crs at higher PEEP to Crs at lower PEEP (Crs ratio (higher/lower)) moderately correlated with NMD and R/I ratio (rho = 0.64, P < 0.001; and rho = 0.67, P < 0.001, respectively).ConclusionsNMD of the quasi-static PV curve and R/I ratio for recruitability assessment are highly correlated. In addition, NMD and R/I ratio correlated with the Crs ratio (higher/lower). Therefore, NMD and R/I ratio could be potential indicators of recruitability that can be performed at the bedside.

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.

Effects of Recruitment Maneuvers on Oxygenation and Intracranial Pressure in the Experimental ARDS Model.

The most efficient recruitment maneuver (RM) for oxygenation in patients under mechanical circulatory support with acute respiratory distress syndrome (ARDS) has not been described yet. In this study, we have evaluated the effects of three recruitment maneuvers on oxygenation and intracranial pressure. 20 sheep have been randomly grouped as follows: ARDS control, ARDS+TV(Tidal Volume), ARDS+CPAP(Continuous Positive Airway Pressure), ARDS+PEEP(Positive End Expiratory Pressure). Arterial blood gas tests have been done before ARDS, after ARDS, and 5,10, and 30 minutes after the maneuver. Intracranial pressures had been followed up. There was a statistically significant increase in Pa02 (Partial arterial oxygen pressure) values in all groups 5 minutes after RM (P > 0,01). There was a statistically increase in Pa02 values in all groups 10 and 30 minutes after the RM (P > 0,01). TV group had significantly more increase in PaO2 increase at the 30th the other groups (P > 0,01). CPAP group had more increase in intracranial pressures just after the RM and at 5 and 10 minutes after the RM. This increase was statistically significant (P > 0,01). All groups had similar intracranial pressure values 30 minutes after the RM. There was no statiscally signifciant difference between the groups (P > 0,05). ICP monitorisation should be carried out in patients with ARDS while performing recruitment maneuvers.

Ventilation Strategies During General Anesthesia for Noncardiac Surgery: A Systematic Review and Meta-Analysis.

The optimal ventilation strategy during general anesthesia is unclear. This systematic review investigated the relationship between ventilation targets or strategies (eg, positive end-expiratory pressure [PEEP], tidal volume, and recruitment maneuvers) and postoperative outcomes. PubMed and Embase were searched on March 8, 2021, for randomized trials investigating the effect of different respiratory targets or strategies on adults undergoing noncardiac surgery. Two investigators reviewed trials for relevance, extracted data, and assessed risk of bias. Meta-analyses were performed for relevant outcomes, and several subgroup analyses were conducted. The certainty of evidence was evaluated using Grading of Recommendations Assessment, Development and Evaluation (GRADE). This review included 63 trials with 65 comparisons. Risk of bias was intermediate for all trials. In the meta-analyses, lung-protective ventilation (ie, low tidal volume with PEEP) reduced the risk of combined pulmonary complications (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.28-0.49; 9 trials; 1106 patients), atelectasis (OR, 0.39; 95% CI, 0.25-0.60; 8 trials; 895 patients), and need for postoperative mechanical ventilation (OR, 0.36; 95% CI, 0.13-1.00; 5 trials; 636 patients). Recruitment maneuvers reduced the risk of atelectasis (OR, 0.44; 95% CI, 0.21-0.92; 5 trials; 328 patients). We found no clear effect of tidal volume, higher versus lower PEEP, or recruitment maneuvers on postoperative pulmonary complications when evaluated individually. For all comparisons across targets, no effect was found on mortality or hospital length of stay. No effect measure modifiers were found in subgroup analyses. The certainty of evidence was rated as very low, low, or moderate depending on the intervention and outcome. Although lung-protective ventilation results in a decrease in pulmonary complications, randomized clinical trials provide only limited evidence to guide specific ventilation strategies during general anesthesia for adults undergoing noncardiac surgery.

Optimized ventilation strategy for surgery on patients with obesity from the perspective of lung protection: A network meta-analysis.

New ventilation modes have been proposed to support the perioperative treatment of patients with obesity, but there is a lack of consensus regarding the optimal strategy. Therefore, a network meta-analysis update of 13 ventilation strategies was conducted to determine the optimal mode of mechanical ventilation as a protective ventilation strategy decreases pulmonary atelectasis caused by inflammation. The following databases were searched: MEDLINE; Cochrane Library; Embase; CINAHL; Google Scholar; and Web of Science for randomized controlled trials of mechanical ventilation in patients with obesity published up to May 1, 2022. Volume-controlled ventilation with individualized positive end-expiratory pressure and a recruitment maneuver (VCV+PEEPind+RM) was found to be the most effective strategy for improving ratio of the arterial O2 partial pressure to the inspiratory O2 concentration (PaO2/FiO2), and superior to pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), volume-controlled ventilation with recruitment maneuver (VCV+RM), volume-controlled ventilation with low positive end-expiratory pressure (VCV+lowPEEP), volume-controlled ventilation with lower positive expiratory end pressure (PEEP) and recruitment maneuver (VCV+lowPEEP+RM), and the mean difference [MD], the 95% confidence intervals [CIs] and [quality of evidence] were: 162.19 [32.94, 291.45] [very low]; 180.74 [59.22, 302.27] [low]; 171.07 [40.60, 301.54] [very low]; 135.14 [36.10, 234.18] [low]; and 139.21 [27.08, 251.34] [very low]. Surface under the cumulative ranking curve (SUCRA) value showed VCV+PEEPind+RM was the best strategy for improving PaO2/FiO2 (SUCRA: 0.963). VCV with high positive PEEP and recruitment maneuver (VCV+highPEEP+RM) was more effective in decreasing postoperative pulmonary atelectasis than the VCV+lowPEEP+RM strategy. It was found that volume-controlled ventilation with high positive expiratory end pressure (VCV+highPEEP), risk ratio [RR] [95% CIs] and [quality of evidence], 0.56 [0.38, 0.81] [moderate], 0.56 [0.34, 0.92] [moderate]. SUCRA value ranked VCV+highPEEP+RM the best strategy for improving postoperative pulmonary atelectasis intervention (SUCRA: 0.933). It should be noted that the quality of evidence was in all cases very low or only moderate. This research suggests that VCV+PEEPind+RM is the optimal ventilation strategy for patients with obesity and is more effective in increasing PaO2/FiO2, improving lung compliance, and among the five ventilation strategies for postoperative atelectasis, VCV+highPEEP+RM had the greatest potential to reduce atelectasis caused by inflammation. https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42021288941.

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.