Beneficial effect of a prone position for patients with hypoxemia after transthoracic esophagectomy

Effects of prone positioning on ARDS outcomes of trauma and surgical patients: a systematic review and meta-analysis

BACKGROUND

Prone position is an option for rescue therapy for acute respiratory distress syndrome. However, there are limited relevant data among trauma and surgical patients, who may be at increased risk for complications following position changes. This study aimed to identify the benefits and risks of proning in this patient subgroup.

METHODS

Follow the PRISMA 2020, MEDLINE and EMBASE database searches were conducted. Additional search of relevant primary literature and review articles was also performed. A random effects model was used to estimate the PF ratio, mortality rate, mechanical ventilator days, and intensive care unit length of stay using Review Manager 5.4.1 software.

RESULTS

Of 1,128 studies, 15 articles were included in this meta-analysis. The prone position significantly improved the PF ratio compared with the supine position (mean difference, 79.26; 95% CI, 53.38 to 105.13). The prone position group had a statistically significant mortality benefit (risk ratio [RR], 0.48; 95% CI, 0.35 to 0.67). Although there was no significant difference in the intensive care unit length of stay, the prone position significantly decreased mechanical ventilator days (-2.59; 95% CI, -4.21 to -0.97). On systematic review, minor complications were frequent, especially facial edema. There were no differences in local wound complications.

CONCLUSIONS

The prone position has comparable complications to the supine position. With its benefits of increased oxygenation and decreased mortality, the prone position can be considered for trauma and surgical patients. A prospective multicenter study is warranted.

Prone position for acute respiratory distress syndrome and the hazards of meta-analysis

BACKGROUND

Researchers have tried unsuccessfully for many years using randomized controlled trials to show the efficacy of prone ventilation in treating ARDS. These failed attempts were of use in designing the successful PROSEVA trial, published in 2013. However, the evidence provided by meta-analyses in support of prone ventilation for ARDS was too low to be conclusive. The present study shows that meta-analysis is indeed not the best approach for the assessment of evidence as to the efficacy of prone ventilation.

METHODS

We performed a cumulative meta-analysis to prove that only the PROSEVA trial, due to its strong protective effect, has substantially impacted on the outcome. We also replicated nine published meta-analyses including the PROSEVA trial. We performed leave-one-out analyses, removing one trial at a time from each meta-analysis, measuring p values for effect size, and also the Cochran's Q test for heterogeneity assessment. We represented these analyses in a scatter plot to identify outlier studies influencing heterogeneity or overall effect size. We used interaction tests to formally identify and evaluate differences with the PROSEVA trial.

RESULTS

The positive effect of the PROSEVA trial accounted for most of the heterogeneity and for the reduction of overall effect size in the meta-analyses. The interaction tests we conducted on the nine meta-analyses formally confirmed the difference in the effectiveness of prone ventilation between the PROSEVA trial the other studies.

CONCLUSIONS

The clinical lack of homogeneity between the PROSEVA trial design and the other studies should have discouraged the use of meta-analysis. Statistical considerations support this hypothesis, suggesting that the PROSEVA trial is an independent source of evidence.

Body position for preventing ventilator-associated pneumonia for critically ill patients: a systematic review and network meta-analysis

Background

The evidence about the best body position to prevent ventilator-associated pneumonia (VAP) is unclear. The aim of this study was to know what the best body position is to prevent VAP, shorten the length of intensive care unit (ICU) and hospital stay, and reduce mortality among patients undergoing mechanical ventilation (MV).

Methods

We performed a network meta-analysis of randomized controlled trials including intubated patients undergoing MV and admitted to an ICU. The assessed interventions were different body positions (i.e., lateral, prone, semi-recumbent) or alternative degrees of positioning in mechanically ventilated patients.

Results

Semi-recumbent and prone positions showed a risk reduction of VAP incidence (RR: 0.38, 95% CI: 0.25–0.52) and mortality (RR: 0.70, 95% CI: 0.50–0.91), respectively, compared to the supine position. The ranking probabilities and the surface under the cumulative ranking displayed as the first best option of treatment the semi-recumbent position to reduce the incidence of VAP (71.4%), the hospital length of stay (68.9%), and the duration of MV (67.6%); and the prone position to decrease the mortality (89.3%) and to reduce the ICU length of stay (59.3%).

Conclusions

Cautiously, semi-recumbent seems to be the best position to reduce VAP incidence, hospital length of stay and the duration of MV. Prone is the most effective position to reduce the risk of mortality and the ICU length of stay, but it showed no effect on the VAP incidence.

Registration PROSPERO CRD42021247547

Supplementary Information

The online version contains supplementary material available at 10.1186/s40560-022-00600-z.

Ocular Injury Associated With Prone Positioning in Adult Critical Care: A Systematic Review and Meta-Analysis

PURPOSE

Prone positioning during the COVID-19 pandemic has become increasingly used as an adjunct to increase oxygenation in critical care patients. It is associated with an adverse event profile. This study sought to investigate the occurrence of ocular injuries reported in prone versus supine groups in adult critical care.

DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review and meta-analysis were carried out in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed, SCOPUS, and the Cochrane Library were searched. The search period was January 1, 1990, to July 1, 2020.

RESULTS

Eleven randomized controlled trials were included, with 2,247 patients. Twenty-eight events were recorded in 3 trials (174 patients) and no events in the other 8 trials (2,073 patients). The rates of eye injury were 5 events in 1,158 patients (1.30%) and 13 events in 1,089 patients (1.19%) in the prone and supine groups, respectively, which were reduced to 2 of 1,158 patients (0.17%) and 2 of 1,089 patients (0.18%), respectively, when reports of eye or eyelid edema were removed. Meta-analysis demonstrated no significant differences between groups with (an OR of 1.40 (95% CI: 0.37-5.27) and without (OR: 0.78; 95% CI: 0.11-5.73) reported edema.

CONCLUSIONS

This meta-analysis showed no significant difference in the rate of reported ocular injury between prone and supine critical care groups. These rates remain higher than the incidence reported during general anesthesia. There is a need for studies in critical care settings in which ocular injury is an end-point and which include extended patient follow-up.

Efficiency of Prolonged Prone Positioning for Mechanically Ventilated Patients Infected with COVID-19

Hypoxemia of the acute respiratory distress syndrome can be reduced by turning patients prone. Prone positioning (PP) is labor intensive, risks unplanned tracheal extubation, and can result in facial tissue injury. We retrospectively examined prolonged, repeated, and early versus later PP for 20 patients with COVID-19 respiratory failure. Blood gases and ventilator settings were collected before PP, at 1, 7, 12, 24, 32, and 39 h after PP, and 7 h after completion of PP. Analysis of variance was used for comparisons with baseline values at supine positions before turning prone. PP for >39 h maintained PaO₂/FiO₂ (P/F) ratios when turned supine; the P/F decrease at 7 h was not significant from the initial values when turned supine. Patients turned prone a second time, when again turned supine at 7 h, had significant decreased P/F. When PP started for an initial P/F ≤ 150 versus P/F > 150, the P/F increased throughout the PP and upon return to supine. Our results show that a single turn prone for >39 h is efficacious and saves the burden of multiple prone turns, and there is no significant advantage to initiating PP when P/F > 150 compared to P/F ≤ 150.

Prognostic Factors to Predict ICU Mortality in Patients with Severe ARDS Who Received Early and Prolonged Prone Positioning Therapy

Early and prolonged prone positioning (PP) therapy improve survival in advanced ARDS; however, the predictors of mortality remain unclear. The study aims to identify predictive factors correlated with mortality and build-up the prognostic score in patients with severe ARDS who received early and prolonged PP therapy. A total of 116 patients were enrolled in this retrospective cohort study. Univariate and multivariate regression models were used to estimate the odds ratio (OR) of mortality. Factors associated with mortality were assessed by Cox regression analysis and presented as the hazard ratio (HR) and 95% CI. In the multivariate regression model, renal replacement therapy (RRT; OR: 4.05, 1.54–10.67), malignant comorbidity (OR: 8.86, 2.22–35.41), and non-influenza-related ARDS (OR: 5.17, 1.16–23.16) were significantly associated with ICU mortality. Age, RRT, non-influenza-related ARDS, malignant comorbidity, and APACHE II score were included in a composite prone score, which demonstrated an area under the curve of 0.816 for predicting mortality risk. In multivariable Cox proportional hazard model, prone score more than 3 points was significantly associated with ICU mortality (HR: 2.13, 1.12–4.07, p = 0.021). We suggest prone score ≥3 points could be a good predictor for mortality in severe ARDS received PP therapy.

Multivariate Meta-Analysis of the Mortality Effect of Prone Positioning in the Acute Respiratory Distress Syndrome

BACKGROUND

The efficacy of prone positioning (PP) as therapy of the acute respiratory distress syndrome (ARDS) has varied in recent meta-analyses. The efficacy question was reviewed using a cohesive multivariate meta-analysis model incorporating all available common time-point data.

METHODS

Data from a core group of 8 randomized controlled trials (2001-2013) utilized in 8 current meta-analyses (2014-2017) was extracted for common time points. Multivariate meta-analysis and meta-regression models for prone-hours per day, mechanical ventilation tidal-volume and baseline patient PaO₂/FiO₂, considered as continuous and categorical predictors, determined the pooled relative risk (RR) of mortality for prone versus supine positioning.

RESULTS

Mortality RR at 28-30 days, 2-3 months and 6-months was not significant overall (P > 0.05). Meta-regression of categorical predictors indicated significant mortality reduction (P ≤ 0.001) for ≥ 12 prone-hours (versus < 12), lung protective ventilation (versus none) and moderate-severe ARDS (versus all ARDS). Meta-regressions of continuous predictors were also significant (P ≤ 0.021) and yielded treatment inflection points of efficacious therapy for ≥ 12 prone-hours per day, ≤ 8.5 mL/kg tidal volume and ≤ PaO₂/FiO₂ ratio of 130.

CONCLUSIONS

The mortality treatment effect of PP in ARDS, was not demonstrated in the unadjusted meta-analysis model. Moderator effects indicated consistent significant benefit of prone positioning. In the absence of individual patient data, multivariate models provide more decisive conclusions than individual time point analyses.

Prone versus Supine Position Ventilation in Adult Patients with Acute Respiratory Distress Syndrome: A Meta-Analysis of Randomized Controlled Trials

The purpose of this meta-analysis was to compare the efficacy and safety of prone versus supine position ventilation for adult acute respiratory distress syndrome (ARDS) patients. The electronic databases of PubMed, Embase, and the Cochrane Library were systematically searched from their inception up to September 2020. The relative risks (RRs) and weighted mean differences (WMDs) with corresponding 95% confidence intervals (CIs) were employed to calculate pooled outcomes using the random-effects models. Twelve randomized controlled trials that had recruited a total of 2264 adults with ARDS were selected for the final meta-analysis. The risk of mortality in patients who received prone position ventilation was 13% lower than for those who received supine ventilation, but this effect was not statistically significant (RR: 0.87; 95% CI: 0.75–1.00; P = 0.055). There were no significant differences between prone and supine position ventilation on the duration of mechanical ventilation (WMD: −0.22; P = 0.883) or ICU stays (WMD: –0.39; P = 0.738). The pooled RRs indicate that patients who received prone position ventilation had increased incidence of pressure scores (RR: 1.23; P = 0.003), displacement of a thoracotomy tube (RR: 3.14; P = 0.047), and endotracheal tube obstruction (RR: 2.45; P = 0.001). The results indicated that prone positioning during ventilation might have a beneficial effect on mortality, though incidence of several adverse events was significantly increased for these patients.

Prone Position for Acute Respiratory Distress Syndrome. A Systematic Review and Meta-Analysis

RATIONALE

The application of prone positioning for acute respiratory distress syndrome (ARDS) has evolved, with recent trials focusing on patients with more severe ARDS, and applying prone ventilation for more prolonged periods.

OBJECTIVES

This review evaluates the effect of prone positioning on 28-day mortality (primary outcome) compared with conventional mechanical ventilation in the supine position for adults with ARDS.

METHODS

We updated the literature search from a systematic review published in 2010, searching MEDLINE, EMBASE, and CENTRAL (through to August 2016). We included randomized, controlled trials (RCTs) comparing prone to supine positioning in mechanically ventilated adults with ARDS, and conducted sensitivity analyses to explore the effects of duration of prone ventilation, concurrent lung-protective ventilation and ARDS severity. Secondary outcomes included Pa_O2/Fi_O2 ratio on Day 4 and an evaluation of adverse events. Meta-analyses used random effects models. Methodologic quality of the RCTs was evaluated using the Cochrane risk of bias instrument, and methodologic quality of the overall body of evidence was evaluated using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) guidelines.

RESULTS

Eight RCTs fulfilled entry criteria, and included 2,129 patients (1,093 [51%] proned). Meta-analysis revealed no difference in mortality (risk ratio [RR], 0.84; 95% confidence interval [CI], 0.68-1.04), but subgroup analyses found lower mortality with 12 hours or greater duration prone (five trials; RR, 0.74; 95% CI, 0.56-0.99) and for patients with moderate to severe ARDS (five trials; RR, 0.74; 95% CI, 0.56-0.99). Pa_O2/Fi_O2 ratio on Day 4 for all patients was significantly higher in the prone positioning group (mean difference, 23.5; 95% CI, 12.4-34.5). Prone positioning was associated with higher rates of endotracheal tube obstruction and pressure sores. Risk of bias was low across the trials.

CONCLUSIONS

Prone positioning is likely to reduce mortality among patients with severe ARDS when applied for at least 12 hours daily.

Prone position in patients with acute respiratory distress syndrome

Acute respiratory distress syndrome occupies a great deal of attention in intensive care units. Despite ample knowledge of the physiopathology of this syndrome, the focus in intensive care units consists mostly of life-supporting treatment and avoidance of the side effects of invasive treatments. Although great advances in mechanical ventilation have occurred in the past 20 years, with a significant impact on mortality, the incidence continues to be high. Patients with acute respiratory distress syndrome, especially the most severe cases, often present with refractory hypoxemia due to shunt, which can require additional treatments beyond mechanical ventilation, among which is mechanical ventilation in the prone position. This method, first recommended to improve oxygenation in 1974, can be easily implemented in any intensive care unit with trained personnel.

Prone position has extremely robust bibliographic support. Various randomized clinical studies have demonstrated the effect of prone decubitus on the oxygenation of patients with acute respiratory distress syndrome measured in terms of the PaO₂/FiO₂ ratio, including its effects on increasing patient survival.

The members of the Respiratory Therapists Committee of the Sociedad Argentina de Terapia Intensiva performed a narrative review with the objective of discovering the available evidence related to the implementation of prone position, changes produced in the respiratory system due to the application of this maneuver, and its impact on mortality. Finally, guidelines are suggested for decision-making.

Prone position in thoracoscopic esophagectomy improves postoperative oxygenation and reduces pulmonary complications

BACKGROUND

While thoracoscopic esophagectomy is a widely performed surgical procedure, only few studies regarding the influence of body position on changes in circulation and breathing, after the surgery, have been reported. This study aimed at evaluating the effect of body position, during surgery, on the postoperative breathing functions of the chest.

METHODS

A total of 266 patients who underwent right-sided transthoracic esophagectomy for esophageal cancer from 2004 to 2012 were included in this study. Fifty-four of them underwent open thoracotomies in the left lateral decubitus position (Group O), 108 underwent thoracoscopic esophagectomy in the left lateral decubitus position (Group L) and 104 patients were treated by thoracoscopic esophagectomy in the prone position (Group P). Two patients in Group P, who presented with intra-operative bleeding and underwent thoracotomy, were subsequently excluded from the pulmonary function analysis.

RESULTS

Two patients in Group P had to be changed from the prone position to the lateral decubitus position and underwent thoracotomy in order to control intra-operative bleeding. Despite the significantly longer chest operation period in Group P, total blood loss was significantly lower in this group when compared to Groups O and L. Furthermore, patients in Group P presented with significantly lower water balance during the perioperative period and markedly higher SpO₂/FiO₂ ratio after the surgery. The incidence of respiratory complications was significantly higher in Group O when compared to the other two groups; however, no significant differences were observed between the Groups L and P.

CONCLUSION

The findings of this study demonstrate that thoracoscopic esophagectomy in the prone position improves postoperative oxygenation and is therefore a potentially superior surgical approach.

S2e guideline: positioning and early mobilisation in prophylaxis or therapy of pulmonary disorders : Revision 2015: S2e guideline of the German Society of Anaesthesiology and Intensive Care Medicine (DGAI)

The German Society of Anesthesiology and Intensive Care Medicine (DGAI) commissioneda revision of the S2 guidelines on "positioning therapy for prophylaxis or therapy of pulmonary function disorders" from 2008. Because of the increasing clinical and scientificrelevance the guidelines were extended to include the issue of "early mobilization"and the following main topics are therefore included: use of positioning therapy and earlymobilization for prophylaxis and therapy of pulmonary function disorders, undesired effects and complications of positioning therapy and early mobilization as well as practical aspects of the use of positioning therapy and early mobilization. These guidelines are the result of a systematic literature search and the subsequent critical evaluation of the evidence with scientific methods. The methodological approach for the process of development of the guidelines followed the requirements of evidence-based medicine, as defined as the standard by the Association of the Scientific Medical Societies in Germany. Recently published articles after 2005 were examined with respect to positioning therapy and the recently accepted aspect of early mobilization incorporates all literature published up to June 2014.

Prone position for acute respiratory failure in adults

BACKGROUND

Acute hypoxaemia de novo or on a background of chronic hypoxaemia is a common reason for admission to intensive care and for provision of mechanical ventilation. Various refinements of mechanical ventilation or adjuncts are employed to improve patient outcomes. Mortality from acute respiratory distress syndrome, one of the main contributors to the need for mechanical ventilation for hypoxaemia, remains approximately 40%. Ventilation in the prone position may improve lung mechanics and gas exchange and could improve outcomes.

OBJECTIVES

The objectives of this review are (1) to ascertain whether prone ventilation offers a mortality advantage when compared with traditional supine or semi recumbent ventilation in patients with severe acute respiratory failure requiring conventional invasive artificial ventilation, and (2) to supplement previous systematic reviews on prone ventilation for hypoxaemic respiratory failure in an adult population.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 1), Ovid MEDLINE (1950 to 31 January 2014), EMBASE (1980 to 31 January 2014), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 31 January 2014) and Latin American Caribbean Health Sciences Literature (LILACS) (1992 to 31 January 2014) in Ovid MEDLINE for eligible randomized controlled trials. We also searched for studies by handsearching reference lists of relevant articles, by contacting colleagues and by handsearching published proceedings of relevant journals. We applied no language constraints, and we reran the searches in CENTRAL, MEDLINE, EMBASE, CINAHL and LILACS in June 2015. We added five new studies of potential interest to the list of "Studies awaiting classification" and will incorporate them into formal review findings during the review update.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that examined the effects of prone position versus supine/semi recumbent position during conventional mechanical ventilation in adult participants with acute hypoxaemia.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed all trials identified by the search and assessed them for suitability, methods and quality. Two review authors extracted data, and three review authors reviewed the data extracted. We analysed data using Review Manager software and pooled included studies to determine the risk ratio (RR) for mortality and the risk ratio or mean difference (MD) for secondary outcomes; we also performed subgroup analyses and sensitivity analyses.

MAIN RESULTS

We identified nine relevant RCTs, which enrolled a total of 2165 participants (10 publications). All recruited participants suffered from disorders of lung function causing moderate to severe hypoxaemia and requiring mechanical ventilation, so they were fairly comparable, given the heterogeneity of specific disease diagnoses in intensive care. Risk of bias, although acceptable in the view of the review authors, was inevitable: Blinding of participants and carers to treatment allocation was not possible (face-up vs face-down).Primary analyses of short- and longer-term mortality pooled from six trials demonstrated an RR of 0.84 to 0.86 in favour of the prone position (PP), but findings were not statistically significant: In the short term, mortality for those ventilated prone was 33.4% (363/1086) and supine 38.3% (395/1031). This resulted in an RR of 0.84 (95% confidence interval (CI) 0.69 to 1.02) marginally in favour of PP. For longer-term mortality, results showed 41.7% (462/1107) for prone and 47.1% (490/1041) for supine positions, with an RR of 0.86 (95% CI 0.72 to 1.03). The quality of the evidence for both outcomes was rated as low as a result of important potential bias and serious inconsistency.Subgroup analyses for mortality identified three groups consistently favouring PP: those recruited within 48 hours of meeting entry criteria (five trials; 1024 participants showed an RR of 0.75 (95% CI 0.59 to 94)); those treated in the PP for 16 or more hours per day (five trials; 1005 participants showed an RR of 0.77 (95% CI 0.61 to 0.99)); and participants with more severe hypoxaemia at trial entry (six trials; 1108 participants showed an RR of 0.77 (95% CI 0.65 to 0.92)). The quality of the evidence for these outcomes was rated as moderate as a result of potentially important bias.Prone positioning appeared to influence adverse effects: Pressure sores (three trials; 366 participants) with an RR of 1.37 (95% CI 1.05 to 1.79) and tracheal tube obstruction with an RR of 1.78 (95% CI 1.22 to 2.60) were increased with prone ventilation. Reporting of arrhythmias was reduced with PP, with an RR of 0.64 (95% CI 0.47 to 0.87).

AUTHORS' CONCLUSIONS

We found no convincing evidence of benefit nor harm from universal application of PP in adults with hypoxaemia mechanically ventilated in intensive care units (ICUs). Three subgroups (early implementation of PP, prolonged adoption of PP and severe hypoxaemia at study entry) suggested that prone positioning may confer a statistically significant mortality advantage. Additional adequately powered studies would be required to confirm or refute these possibilities of subgroup benefit but are unlikely, given results of the most recent study and recommendations derived from several published subgroup analyses. Meta-analysis of individual patient data could be useful for further data exploration in this regard. Complications such as tracheal obstruction are increased with use of prone ventilation. Long-term mortality data (12 months and beyond), as well as functional, neuro-psychological and quality of life data, are required if future studies are to better inform the role of PP in the management of hypoxaemic respiratory failure in the ICU.

Minimally invasive esophagectomy: Lateral decubitus vs. prone positioning; systematic review and pooled analysis

The uptake of minimally invasive esophagectomy (MIE) has increased vastly over the last decade, with proven short-term benefits over an open approach. The aim of this pooled analysis was to compare clinical outcomes of Minimally Invasive Esophagectomy (MIE) performed in the prone and lateral decubitus positions. A systematic literature search (2000-2015) was undertaken for publications that compared patients who underwent MIE in the lateral decubitus (LD) or prone (PR) positions. Weighted mean difference (WMD) was calculated for the effect size of LD positioning on continuous variables and Pooled odds ratios (POR) for discrete variables. Ten relevant publications comprising 723 patients who underwent minimally invasive esophagectomy were included; 387 in the LD group and 336 in the PR group. There was no significant difference between the groups in terms of in-hospital mortality, total morbidity, anastomotic leak, chylothorax, laryngeal nerve palsy, average operative time, and length hospital stay. LD MIE was associated with a non-significant increase in pulmonary complications (POR = 1.65; 95% C.I. 0.93 to 2.92; P = 0.09), and significant increases in estimated blood loss (WMD = 36.03; 95% 14.37 to 57.69; P = 0.001) and a reduced average mediastinal lymph node harvest (WMD = -2.17; 95% C.I. -3.82 to -0.52; P = 0.01) when compared to prone MIE. Pooled analysis suggests that prone MIE is superior to lateral decubitus MIE with reduced pulmonary complications, estimated blood loss and increased mediastinal lymph node harvest. Further studies are needed to explain performance-shaping factors and their influence on oncological clearance and short-term outcomes.

The efficacy and safety of prone positioning in adults patients with acute respiratory distress syndrome: a meta-analysis of randomized controlled trials

BACKGROUND

Prone positioning for acute respiratory distress syndrome (ARDS) has no impact on mortality despite significant improvements in oxygenation. However, a recent trial demonstrated reduced mortality rates in the prone position for severe ARDS. We evaluated effects of prone position duration and protective lung strategies on mortality rates in ARDS.

METHODS

We extensively searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials to identify randomized controlled trials (RCTs) reporting on prone positioning during acute respiratory failure in adults for inclusion in our meta-analysis.

RESULTS

Eight trials met our inclusion criteria, Totals of 1,099 and 1,042 patients were randomized to the prone and supine ventilation positions. The mortality rates associated with the prone and supine positions were 41% and 47% [risk ratio (RR), 0.90; 95% confidence interval (CI), 0.82-0.98, P=0.02], but the heterogeneity was moderate (P=0.01, I(2)=61%). In a subgroup analysis, the mortality rates for lung protective ventilation (RR 0.73, 95% CI, 0.62-0.86, P=0.0002) and duration of prone positioning >12 h (RR 0.75, 95% CI, 0.65-0.87, P<0.0001) were reduced in the prone position. Prone positioning was not associated with an increased incidence of cardiac events (RR 1.01, 95% CI, 0.87-1.17) or ventilator associated pneumonia (RR 0.88, 95% CI, 0.71-1.09), but it was associated with an increased incidence of pressure sores (RR 1.23, 95% CI, 1.07-1.41) and endotracheal dislocation (RR 1.33, 95% CI, 1.02-1.74).

CONCLUSIONS

Prone positioning tends to reduce the mortality rates in ARDS patients, especially when used in conjunction with a lung protective strategy and longer prone position durations. Prone positioning for ARDS patients should be prioritized over other invasive procedures because related life-threatening complications are rare. However, further additional randomized controlled design to study are required for confirm benefit of prone position in ARDS.

Effect of prone positioning during mechanical ventilation on mortality among patients with acute respiratory distress syndrome: a systematic review and meta-analysis

BACKGROUND

Mechanical ventilation in the prone position is used to improve oxygenation and to mitigate the harmful effects of mechanical ventilation in patients with acute respiratory distress syndrome (ARDS). We sought to determine the effect of prone positioning on mortality among patients with ARDS receiving protective lung ventilation.

METHODS

We searched electronic databases and conference proceedings to identify relevant randomized controlled trials (RCTs) published through August 2013. We included RCTs that compared prone and supine positioning during mechanical ventilation in patients with ARDS. We assessed risk of bias and obtained data on all-cause mortality (determined at hospital discharge or, if unavailable, after longest follow-up period). We used random-effects models for the pooled analyses.

RESULTS

We identified 11 RCTs (n=2341) that met our inclusion criteria. In the 6 trials (n=1016) that used a protective ventilation strategy with reduced tidal volumes, prone positioning significantly reduced mortality (risk ratio 0.74, 95% confidence interval 0.59-0.95; I2=29%) compared with supine positioning. The mortality benefit remained in several sensitivity analyses. The overall quality of evidence was high. The risk of bias was low in all of the trials except one, which was small. Statistical heterogeneity was low (I2<50%) for most of the clinical and physiologic outcomes.

INTERPRETATION

Our analysis of high-quality evidence showed that use of the prone position during mechanical ventilation improved survival among patients with ARDS who received protective lung ventilation.

Prone positioning reduces mortality from acute respiratory distress syndrome in the low tidal volume era: a meta-analysis

PURPOSE

Prone positioning for ARDS has been performed for decades without definitive evidence of clinical benefit. A recent multicenter trial demonstrated for the first time significantly reduced mortality with prone positioning. This meta-analysis was performed to integrate these findings with existing literature and test whether differences in tidal volume explain conflicting results among randomized trials.

METHODS

Studies were identified using MEDLINE, EMBASE, Cochrane Register of Controlled Trials, LILACS, and citation review. Included were randomized trials evaluating the effect on mortality of prone versus supine positioning during conventional ventilation for ARDS. The primary outcome was risk ratio of death at 60 days meta-analyzed using random effects models. Analysis stratified by high (>8 ml/kg predicted body weight) or low (≤ 8 ml/kg PBW) mean baseline tidal volume was planned a priori.

RESULTS

Seven trials were identified including 2,119 patients, of whom 1,088 received prone positioning. Overall, prone positioning was not significantly associated with the risk ratio of death (RR 0.83; 95% CI 0.68-1.02; p = 0.073; I (2) = 64%). When stratified by high or low tidal volume, prone positioning was associated with a significant decrease in RR of death only among studies with low baseline tidal volume (RR 0.66; 95% CI 0.50-0.86; p = 0.002; I (2) = 25%). Stratification by tidal volume explained over half the between-study heterogeneity observed in the unstratified analysis.

CONCLUSIONS

Prone positioning is associated with significantly reduced mortality from ARDS in the low tidal volume era. Substantial heterogeneity across studies can be explained by differences in tidal volume.

Feasibility and effectiveness of prone position in morbidly obese patients with ARDS: a case-control clinical study

BACKGROUND

Obese patients are at risk for developing atelectasis and ARDS. Prone position (PP) may reduce atelectasis, and it improves oxygenation and outcome in severe hypoxemic patients with ARDS, but little is known about its effect in obese patients with ARDS.

METHODS

Morbidly obese patients (BMI ≥ 35 kg/m²) with ARDS (Pao₂/FIo₂ ratio ≤ 200 mm Hg) were matched to nonobese (BMI < 30 kg/m²) patients with ARDS in a case-control clinical study. The primary end points were safety and complications of PP; the secondary end points were the effect on oxygenation (Pao₂/FIo₂ ratio at the end of PP), length of mechanical ventilation and ICU stay, nosocomial infections, and mortality.

RESULTS

Between January 2005 and December 2009, 149 patients were admitted for ARDS. Thirty-three obese patients were matched with 33 nonobese patients. Median (25th-75th percentile) PP duration was 9 h (6-11 h) in obese patients and 8 h (7-12 h) in nonobese patients (P = .28). We collected 51 complications: 25 in obese and 26 in nonobese patients. The number of patients with at least one complication was similar across groups (n = 10, 30%). Pao₂/FIo₂ ratio increased significantly more in obese patients (from 118 ± 43 mm Hg to 222 ± 84 mm Hg) than in nonobese patients (from 113 ± 43 mm Hg to 174 ± 80 mm Hg; P = .03). Length of mechanical ventilation, ICU stay, and nosocomial infections did not differ significantly, but mortality at 90 days was significantly lower in obese patients (27% vs 48%, P < .05).

CONCLUSIONS

PP seems safe in obese patients and may improve oxygenation more than in nonobese patients. Obese patients could be a subgroup of patients with ARDS who may benefit the most of PP.

Surgical quality of care in esophageal malignancies

Aim: Esophagectomy is the primary surgical treatment for localized malignant neoplasms of the esophagus, and while outcomes have shown that substantial improvement has been made, the ceiling for improvement is still high. Methods: A total of 2506 publications published from January 2002 to March 2012 were identified from PubMed, MEDLINE and the Cochrane Library using the keywords: ‘esophagectomy’, ‘esophagus’, ‘neoplasm’ and ‘cancer’ to identify quality key surgical articles in esophagectomy that were broken down into three groups: preoperative, intraoperative and postoperative care. Discussion: There have been limited preoperative surgical trials, mostly in preoperative antibiotic use, which have led to changes in surgical management. Key and substantial changes have occurred in the intraoperative management for esophageal malignancies around surgical anastomosis technique and anesthesia. Nutritional outcomes still remain a key challenge, and currently there is no established standard of care in the postoperative management of esophagectomy patients. Conclusion: We established quality parameters for leak rates, overall morbidity and mortality, and these form the foundation from which all esophageal surgeons should rank their results. We then utilized the techniques described above to maintain those rates or, better yet, to significantly improve those rates in each surgeons’ practice.

Thoracoscopic esophagectomy in the prone position

BACKGROUND

Minimally invasive esophageal surgery has arisen in an attempt to reduce the significant complications associated with esophagectomy. Despite proposed technical and physiological advantages, the prone position technique has not been widely adopted. This article reviews the current status of prone thoracoscopic esophagectomy.

METHODS

A systematic literature search was performed to identify all published clinical studies related to prone esophagectomy. Medline, EMBASE and Google Scholar were searched using the keywords "prone," "thoracoscopic," and "esophagectomy" to identify articles published between January 1994 and September 2010. A critical review of these studies is given, and where appropriate the technique is compared to the more traditional minimally invasive technique utilising the left lateral decubitus position.

RESULTS

Twelve articles reporting the outcomes following prone thoracoscopic oesophagectomy were tabulated. These studies were all non-randomised single-centre prospective or retrospective studies of which four compared the technique to traditional minimally invasive surgery. Although prone esophagectomy is demonstrated as being both feasible and safe, there is no convincing evidence that it is superior to other forms of esophageal surgery. Most authors comment that the prone position is associated with superior surgical ergonomics and theoretically offers a number of physiological benefits.

CONCLUSION

The ideal approach within minimally invasive esophageal surgery continues to be a subject of debate since no single method has produced outstanding results. Further clinical studies are required to see whether ergonomic advantages of the prone position can be translated into improved patient outcomes.

Ventilator-associated pneumonia: role of positioning

PURPOSE OF REVIEW

Ventilator-associated pneumonia (VAP) is a lung infection commonly acquired following tracheal intubation. This review assesses the role of the supine semirecumbent and the prone position as VAP preventive strategies and calls attention for further investigation on novel body positions that could potentially reduce risks of VAP.

RECENT FINDINGS

The most recent studies on the semirecumbent position failed to achieve an orientation of the head of the bed higher than 30° and did not corroborate any benefit of the semirecumbent position on VAP, as reported in earlier studies. To date, there is clear evidence that the supine horizontal body position increases risks of pulmonary aspiration and VAP, particularly when patients are enterally fed. Laboratory reports are emphasizing the importance of an endotracheal tube-oropharynx-trachea axis below horizontal to avoid VAP. The prone position potentially increases drainage of oropharyngeal and airways secretions and recent evidence is supporting its beneficial effects. However, several associated adverse effects preclude its regular use as a VAP preventive strategy for patients other than those with acute respiratory distress syndrome.

SUMMARY

Body position greatly affects several pathogenetic mechanisms of VAP. The current evidence recommends avoidance of supine horizontal position in order to prevent aspiration of colonized gastric contents. The semirecumbent position has proven benefits and should be routinely used but there is still limited evidence to recommend the lowest orientation of the bed at which the patient can be safely maintained. Results from pioneering laboratory investigation call attention to new possible positions, that is lateral Trendelenburg position, aimed to avoid pulmonary aspiration and to enhance mucus clearance in intubated patients.

Should thoracoscopic three-stage esophagectomy be performed in the prone or left lateral decubitus position?

A best evidence topic was written according to a structured protocol. The question addressed was whether the thoracoscopic phase of three-stage minimally-invasive esophagectomy is best performed in the prone or left lateral decubitus position. A total of 31 papers were found using the reported searches, of which seven represented the best evidence to answer the clinical question. The authors, date, journal, study type, population, main outcome measures and results are tabulated. We conclude that there is no convincing evidence that prone thoracoscopic esophagectomy is superior to left lateral decubitus positioning. Four papers retrospectively compared the prone and lateral techniques, and while the authors suggested that the prone position was associated with better surgical ergonomics due to the effects of gravity pooling blood outside the operative view and the reduced need for lung retraction, outcomes were not significantly different. All four studies had significant limitations, such as small patient populations and sequential operating with the possible effect of a learning curve. Two studies compared respiratory and haemodynamic changes associated with prone positioning and suggest that it is physiologically well tolerated and may offer better oxygenation, similar to that seen in the prone positioning of acute respiratory distress patients. The evidence for prone thoracoscopic esophagectomy is currently not mature enough to reach any significant conclusions, and randomized studies are required.

Prone ventilation reduces mortality in patients with acute respiratory failure and severe hypoxemia: systematic review and meta-analysis

BACKGROUND

Prone position ventilation for acute hypoxemic respiratory failure (AHRF) improves oxygenation but not survival, except possibly when AHRF is severe.

OBJECTIVE

To determine effects of prone versus supine ventilation in AHRF and severe hypoxemia [partial pressure of arterial oxygen (PaO(2))/inspired fraction of oxygen (FiO(2)) <100 mmHg] compared with moderate hypoxemia (100 mmHg < or = PaO(2)/FiO(2) < or = 300 mmHg).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Electronic databases (to November 2009) and conference proceedings.

METHODS

Two authors independently selected and extracted data from parallel-group randomized controlled trials comparing prone with supine ventilation in mechanically ventilated adults or children with AHRF. Trialists provided subgroup data. The primary outcome was hospital mortality in patients with AHRF and PaO(2)/FiO(2) <100 mmHg. Meta-analyses used study-level random-effects models.

RESULTS

Ten trials (N = 1,867 patients) met inclusion criteria; most patients had acute lung injury. Methodological quality was relatively high. Prone ventilation reduced mortality in patients with PaO(2)/FiO(2) <100 mmHg [risk ratio (RR) 0.84, 95% confidence interval (CI) 0.74-0.96; p = 0.01; seven trials, N = 555] but not in patients with PaO(2)/FiO(2) > or =100 mmHg (RR 1.07, 95% CI 0.93-1.22; p = 0.36; seven trials, N = 1,169). Risk ratios differed significantly between subgroups (interaction p = 0.012). Post hoc analysis demonstrated statistically significant improved mortality in the more hypoxemic subgroup and significant differences between subgroups using a range of PaO(2)/FiO(2) thresholds up to approximately 140 mmHg. Prone ventilation improved oxygenation by 27-39% over the first 3 days of therapy but increased the risks of pressure ulcers (RR 1.29, 95% CI 1.16-1.44), endotracheal tube obstruction (RR 1.58, 95% CI 1.24-2.01), and chest tube dislodgement (RR 3.14, 95% CI 1.02-9.69). There was no statistical between-trial heterogeneity for most clinical outcomes.

CONCLUSIONS

Prone ventilation reduces mortality in patients with severe hypoxemia. Given associated risks, this approach should not be routine in all patients with AHRF, but may be considered for severely hypoxemic patients.

Prone positioning in hypoxemic respiratory failure: meta-analysis of randomized controlled trials

PURPOSE

Prone positioning is used to improve oxygenation in patients with hypoxemic respiratory failure (HRF). However, its role in clinical practice is not yet clearly defined. The aim of this meta-analysis was to assess the effect of prone positioning on relevant clinical outcomes, such as intensive care unit (ICU) and hospital mortality, days of mechanical ventilation, length of stay, incidence of ventilator-associated pneumonia (VAP) and pneumothorax, and associated complications.

METHODS

We used literature search of MEDLINE, Current Contents, and Cochrane Central Register of Controlled Trials. We focused only on randomized controlled trials reporting clinical outcomes in adult patients with HRF. Four trials met our inclusion criteria, including 662 patients randomized to prone ventilation and 609 patients to supine ventilation.

RESULTS

The pooled odds ratio (OR) for the ICU mortality in the intention-to-treat analysis was 0.97 (95% confidence interval [CI], 0.77-1.22), for the comparison between prone and supine ventilated patients. Interestingly, the pooled OR for the ICU mortality in the selected group of the more severely ill patients favored prone positioning (OR, 0.34; 95% CI, 0.18-0.66). The duration of mechanical ventilation and the incidence of pneumothorax were not different between the 2 groups. The incidence of VAP was lower but not statistically significant in patients treated with prone positioning (OR, 0.81; 95% CI, 0.61-1.10). However, prone positioning was associated with a higher risk of pressure sores (OR, 1.49; 95% CI, 1.17-1.89) and a trend for more complications related to the endotracheal tube (OR, 1.30; 95% CI, 0.94-1.80).

CONCLUSIONS

Despite the inherent limitations of the meta-analytic approach, it seems that prone positioning has no discernible effect on mortality in patients with HRF. It may decrease the incidence of VAP at the expense of more pressure sores and complications related to the endotracheal tube. However, a subgroup of the most severely ill patients may benefit most from this intervention.

Effect of mechanical ventilation in the prone position on clinical outcomes in patients with acute hypoxemic respiratory failure: a systematic review and meta-analysis

BACKGROUND

Mechanical ventilation in the prone position is used to improve oxygenation in patients with acute hypoxemic respiratory failure. We sought to determine the effect of mechanical ventilation in the prone position on mortality, oxygenation, duration of ventilation and adverse events in patients with acute hypoxemic respiratory failure.

METHODS

In this systematic review we searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and Science Citation Index Expanded for articles published from database inception to February 2008. We also conducted extensive manual searches and contacted experts. We extracted physiologic data and clinically relevant outcomes.

RESULTS

Thirteen trials that enrolled a total of 1559 patients met our inclusion criteria. Overall methodologic quality was good. In 10 of the trials (n = 1486) reporting this outcome, we found that prone positioning did not reduce mortality among hypoxemic patients (risk ratio [RR] 0.96, 95% confidence interval [CI] 0.84-1.09; p = 0.52). The lack of effect of ventilation in the prone position on mortality was similar in trials of prolonged prone positioning and in patients with acute lung injury. In 8 of the trials (n = 633), the ratio of partial pressure of oxygen to inspired fraction of oxygen on day 1 was 34% higher among patients in the prone position than among those who remained supine (p < 0.001); these results were similar in 4 trials on day 2 and in 5 trials on day 3. In 9 trials (n = 1206), the ratio in patients assigned to the prone group remained 6% higher the morning after they returned to the supine position compared with patients assigned to the supine group (p = 0.07). Results were quantitatively similar but statistically significant in 7 trials on day 2 and in 6 trials on day 3 (p = 0.001). In 5 trials (n = 1004), prone positioning was associated with a reduced risk of ventilator-associated pneumonia (RR 0.81, 95% CI 0.66-0.99; p = 0.04) but not with a reduced duration of ventilation. In 6 trials (n = 504), prone positioning was associated with an increased risk of pressure ulcers (RR 1.36, 95% CI 1.07-1.71; p = 0.01). Most analyses found no to moderate between-trial heterogeneity.

INTERPRETATION

Mechanical ventilation in the prone position does not reduce mortality or duration of ventilation despite improved oxygenation and a decreased risk of pneumonia. Therefore, it should not be used routinely for acute hypoxemic respiratory failure. However, a sustained improvement in oxygenation may support the use of prone positioning in patients with very severe hypoxemia, who have not been well-studied to date.

Efficacy of prone ventilation in adult patients with acute respiratory failure: a meta-analysis

PURPOSE

The use of prone ventilation in acute respiratory failure has been investigated by several randomized controlled trials in the recent past. To date, there has been no systematic review or meta-analysis of these trials.

MATERIAL AND METHODS

Systematic literature search was performed between 1966 and July 2006 to identify randomized trials evaluating prone ventilation. Outcome measures included mortality, changes in oxygenation, incidence of pneumonia, duration of mechanical ventilation, intensive care unit (ICU) and hospital stay, cost-effectiveness, and adverse effects including pressure sores, endotracheal tube, or intravascular catheter complications.

RESULTS

Prone ventilation was not associated with reduction in mortality, but improvement in oxygenation was statistically significant (mean difference, 21.2 mm Hg; P < .001). There was no significant difference in incidence of pneumonia, ICU stay, and endotracheal tube complications. There was a trend toward an increased incidence of pressure sores in prone ventilated patients (odds ratio = 1.95; 95% confidence interval, 0.09-4.15; P = .08). The data on other outcomes were not suitable for meta-analysis.

CONCLUSIONS

The use of prone ventilation is associated with improved oxygenation. It is not associated with a reduction in mortality, pneumonia, or ICU stay and may be associated with an increased incidence of pressure sores.

Sequential use of midazolam and propofol for long-term sedation in postoperative mechanically ventilated patients

Acute withdrawal syndromes, including agitation and a long weaning time, are common adverse effects after long-term sedation with midazolam. We performed this study to determine whether the sequential use of midazolam and propofol could reduce adverse effects as compared with midazolam alone. We studied 26 patients receiving mechanical ventilation for three or more days after surgery. Patients were randomly assigned to two groups. In Group M, patients were sedated with midazolam alone. In Group M-P, midazolam was switched to propofol approximately 24 h before the expected stopping of sedation. The level of sedation was maintained at 4 or 5 on the Ramsay sedation scale. The sedation agitation scale was evaluated for 24 h after extubation. The recovery time from stopping of sedation to extubation was significantly shorter in Group M-P (1.3 +/- 0.4 h) compared with Group M (4.0 +/- 2.4 h). The incidence of agitation in Group M-P (8%) was significantly less frequent than that in Group M (54%). The results indicate that sequential use of midazolam and propofol for long-term sedation could reduce the incidence of agitation compared with midazolam alone.

IMPLICATIONS

Our study indicates that sequential use of midazolam and propofol could reduce the incidence of agitation compared with midazolam alone.