Prone positioning in patients with moderate and severe acute respiratory distress syndrome: a randomized controlled trial. Comparison of prone positioning and high-frequency oscillatory ventilation in patients with acute respiratory distress syndrome* Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. Selecting and Appraising Studies for a Systematic Review Subgroup analysis and other (mis)uses of baseline data in clinical trials Lung recruitment in patients with the acute respiratory distress syndrome. Prone positioning in acute respiratory distress syndrome: a multicenter randomized clinical trial High‐frequency oscillatory ventilation following prone positioning prevents a further impairment in oxygenation* Effect of prone positioning on clinical outcomes in children with acute lung injury: a randomized controlled trial. Effects of systematic prone positioning in hypoxemic acute respiratory failure: a randomized controlled trial. Clinical trial design--effect of prone positioning on clinical outcomes in infants and children with acute respiratory distress syndrome. Prone positioning can be safely performed in critically ill infants and children* Influence of positioning on ventilation-perfusion relationships in severe adult respiratory distress syndrome. Prone position as prevention of lung injury in comatose patients: a prospective, randomized, controlled study Quality-adjusted survival in the first year after the acute respiratory distress syndrome. Does gas exchange response to prone position predict mortality in hypoxemic acute respiratory failure? Effects of prone position on inflammatory markers in patients with ARDS due to community-acquired pneumonia. Incidence and outcomes of acute lung injury. Effect of prone positioning on the survival of patients with acute respiratory failure. [Effect of bronchial drainage on the improvement in gas exchange observed in ventral decubitus in ARDS]. Two-year outcomes, health care use, and costs of survivors of acute respiratory distress syndrome. Decrease in Paco2 with prone position is predictive of improved outcome in acute respiratory distress syndrome* Developing optimal search strategies for detecting clinically sound treatment studies in EMBASE. Prone positioning improves oxygenation in post-traumatic lung injury--a prospective randomized trial. A multicenter trial of prolonged prone ventilation in severe acute respiratory distress syndrome. Language bias in randomised controlled trials published in English and German High-frequency oscillatory ventilation for acute respiratory distress syndrome in adults: a randomized, controlled trial. Beneficial effect of a prone position for patients with hypoxemia after transthoracic esophagectomy
CONTEXT Post hoc analysis of a previous trial has suggested that prone positioning may improve survival in patients with severe hypoxemia and with acute respiratory distress syndrome ( ARDS ) . OBJECTIVE To assess possible outcome benefits of prone positioning in patients with moderate and severe hypoxemia who are affected by ARDS . DESIGN , SETTING , AND PATIENTS The Prone-Supine II Study , a multicenter , unblinded , r and omized controlled trial conducted in 23 centers in Italy and 2 in Spain . Patients were 342 adults with ARDS receiving mechanical ventilation , enrolled from February 2004 through June 2008 and prospect ively stratified into subgroups with moderate ( n = 192 ) and severe ( n = 150 ) hypoxemia . INTERVENTIONS Patients were r and omized to undergo supine ( n = 174 ) or prone ( 20 hours per day ; n = 168 ) positioning during ventilation . MAIN OUTCOME MEASURES The primary outcome was 28-day all-cause mortality . Secondary outcomes were 6-month mortality and mortality at intensive care unit discharge , organ dysfunctions , and the complication rate related to prone positioning . RESULTS Prone and supine patients from the entire study population had similar 28-day ( 31.0 % vs 32.8 % ; relative risk [ RR ] , 0.97 ; 95 % confidence interval [ CI ] , 0.84 - 1.13 ; P = .72 ) and 6-month ( 47.0 % vs 52.3 % ; RR , 0.90 ; 95 % CI , 0.73 - 1.11 ; P = .33 ) mortality rates , despite significantly higher complication rates in the prone group . Outcomes were also similar for patients with moderate hypoxemia in the prone and supine groups at 28 days ( 25.5 % vs 22.5 % ; RR , 1.04 ; 95 % CI , 0.89 - 1.22 ; P = .62 ) and at 6 months ( 42.6 % vs 43.9 % ; RR , 0.98 ; 95 % CI , 0.76 - 1.25 ; P = .85 ) . The 28-day mortality of patients with severe hypoxemia was 37.8 % in the prone and 46.1 % in the supine group ( RR , 0.87 ; 95 % CI , 0.66 - 1.14 ; P = .31 ) , while their 6-month mortality was 52.7 % and 63.2 % , respectively ( RR , 0.78 ; 95 % CI , 0.53 - 1.14 ; P = .19 ) . CONCLUSION Data from this study indicate that prone positioning does not provide significant survival benefit in patients with ARDS or in subgroups of patients with moderate and severe hypoxemia . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00159939 Objective : Both prone position and high-frequency oscillatory ventilation ( HFOV ) have the potential to facilitate lung recruitment , and their combined use could thus be synergetic on gas exchange . Keeping the lung open could also potentially be lung protective . The aim of this study was to compare physiologic and proinflammatory effects of HFOV , prone positioning , or their combination in severe acute respiratory distress syndrome ( ARDS ) . Design : Prospect i ve , comparative r and omized study . Setting : A medical intensive care unit . Patients : Thirty-nine ARDS patients with a Pao2/Fio2 ratio < 150 mm Hg at positive end-expiratory pressure ≥5 cm H2O . Interventions : After 12 hrs on conventional lung-protective mechanical ventilation ( tidal volume 6 mL/kg of ideal body weight , plateau pressure not exceeding the upper inflection point , and a maximum of 35 cm H2O ; supine-CV ) , 39 patients were r and omized to receive one of the following 12-hr periods : conventional lung-protective mechanical ventilation in prone position ( prone-CV ) , HFOV in supine position ( supine-HFOV ) , or HFOV in prone position ( prone-HFOV ) . Measurements and Main Results : Prone-CV ( from 138 ± 58 mm Hg to 217 ± 110 mm Hg , p < .0001 ) and prone-HFOV ( from 126 ± 40 mm Hg to 227 ± 64 mm Hg , p < 0.0001 ) improved the Pao2/Fio2 ratio whereas supine-HFOV did not alter the Pao2/Fio2 ratio ( from 134 ± 57 mm Hg to 138 ± 48 mm Hg ) . The oxygenation index ( { mean airway pressure × Fio2 × 100}/Pao2 ) decreased in the prone-CV and prone-HFOV groups and was lower than in the supine-HFOV group . Interleukin-8 increased significantly in the bronchoalveolar lavage fluid ( BALF ) in supine-HFOV and prone-HFOV groups compared with prone-CV and supine-CV . Neutrophil counts were higher in the supine-HFOV group than in the prone-CV group . Conclusions : Although HFOV in the supine position does not improve oxygenation or lung inflammation , the prone position increases oxygenation and reduces lung inflammation  in ARDS patients .  Prone-HFOV produced similar improvement in oxygenation like prone-CV but was associated with higher BALF indexes of inflammation . In contrast , supine-HFOV did not improve gas exchange and was associated with enhanced lung inflammation BACKGROUND Traditional approaches to mechanical ventilation use tidal volumes of 10 to 15 ml per kilogram of body weight and may cause stretch-induced lung injury in patients with acute lung injury and the acute respiratory distress syndrome . We therefore conducted a trial to determine whether ventilation with lower tidal volumes would improve the clinical outcomes in these patients . METHODS Patients with acute lung injury and the acute respiratory distress syndrome were enrolled in a multicenter , r and omized trial . The trial compared traditional ventilation treatment , which involved an initial tidal volume of 12 ml per kilogram of predicted body weight and an airway pressure measured after a 0.5-second pause at the end of inspiration ( plateau pressure ) of 50 cm of water or less , with ventilation with a lower tidal volume , which involved an initial tidal volume of 6 ml per kilogram of predicted body weight and a plateau pressure of 30 cm of water or less . The primary outcomes were death before a patient was discharged home and was breathing without assistance and the number of days without ventilator use from day 1 to day 28 . RESULTS The trial was stopped after the enrollment of 861 patients because  mortality was lower in the group treated with lower tidal volumes than in the group treated with traditional tidal volumes ( 31.0 percent vs. 39.8 percent , P=0.007 ) , and the number of days without ventilator use during the first 28 days after r and omization was greater in this group ( mean [ + /-SD ] , 12+/-11 vs. 10+/-11 ; P=0.007 ) . The mean tidal volumes on days 1 to 3 were 6.2+/-0.8 and 11.8+/-0.8 ml per kilogram of predicted body weight ( P<0.001 ) , respectively , and the mean plateau pressures were 25+/-6 and 33+/-8 cm of water ( P<0.001 ) , respectively . CONCLUSIONS In patients with acute lung injury and the acute respiratory distress syndrome , mechanical ventilation with a lower tidal volume than is traditionally used results in decreased mortality and increases the number of days without ventilator use Systematic Review Series Series Editors : Cynthia Mulrow , MD , MSc Deborah Cook , MD , MSc The last article in this series outlined methods with which to search the literature for studies on the clinical question that generates a systematic review [ 1 ] . Herein , we discuss the subsequent steps of selecting and appraising  studies  for a review . Both of these steps involve important judgments that can influence the results of a review . In selecting studies , review ers judge the relevance of the studies to the review question . In appraising studies , review ers judge numerous features of design and analysis . Some of these judgments are easy to make ; others are more difficult and prone to error . To be confident in their decisions , review ers should use methods that are reliable ( the results do not change if the procedure is repeated ) , impartial ( not influenced by the study results ) , and explicit ( unambiguous ) [ 2 ] . These strategies for selection and appraisal are sensible , and they distinguish most systematic review s from most narrative review s. However , evidence to support the importance of some of the methods we suggest is either scant or conflicting ; readers are referred to the original research on these approaches for more details . Selecting Studies for Systematic Review s If review ers perform a comprehensive search of the literature using the methods described previously in this series [ 1 ] , they will probably have assembled a large sample of articles . This sample will include most ( ideally , all ) studies that are relevant to the review question ( that is , the sensitivity of the search will be high ) . Inevitably , because such a wide net is cast , articles not pertinent to the clinical question will be retrieved ( that is , the specificity of the search will be modest ) . Thus , the review ers ' next task is to sort through all of the potentially relevant articles and select those that will be included in the review . To do so , review ers adopt several of the tactics listed in Table 1 and Table 2 for planning and executing the selection process ( in effect , improving the specificity of the search ) ; these tactics are described below . Table 1 . Planning Study Selection Table 2 . Strategies for Selecting and Appraising Studies Begin with a Well-Built Clinical Question Review ers should ensure that the question for review includes the four elements of a well-built clinical question [ 3 , 4 ] : the patients of interest , the main interventions under investigation , the comparison interventions , and the clinical outcomes of interest . By including these four elements , review ers can better focus the selection process . Choose Selection Criteria That Fit the Clinical Question Consider a systematic review of the effectiveness of a drug treatment ( for example , a proton-pump inhibitor ) for patients with a particular disorder ( such as esophageal reflux ) . Review ers need to decide whether to include studies of patients with any symptoms of reflux , only those with classic symptoms , or only those in whom definitive diagnostic tests have confirmed the presence of reflux . In addition , review ers might choose to include studies of patients with different comorbid conditions ; patients from different demographic or geographic or cultural background s ; or patients from different health systems , such as inpatient or community population s. Similarly , review ers should use selection criteria that reflect the main and comparison interventions of interest . In our esophageal reflux example , review ers would need to decide whether to include studies of a particular drug or studies of all agents in that drug 's class and whether to include studies of any dose and regimen or only studies with a specific regimen . For the comparison interventions , the review ers would decide whether to include studies that compare the experimental drug with alternate treatments ( such as antacids or histamine-2-receptor antagonists ) , with placebo , or with both . For the clinical outcomes , review ers have analogous tasks of defining the outcomes and translating them into criteria . In our example , the review ers would start by listing each clinical outcome ( for example , whether the outcome was endoscopic or clinical and whether it focused on cure or persistence ) and then decide whether to include studies that reported any outcome or only those with certain clinical ly important outcomes ( such as improvement in symptoms at 1 year ) . After thoroughly considering each element of the review question , review ers compile a set of explicit selection criteria . When these criteria are not explicit , the results of the review are more prone to error [ 5 , 6 ] . Reporting the selection criteria used in a review is extremely important to readers because the criteria indicate the relevance of the review to the readers ' clinical practice . Specify the Types of Study Design To Be Included After creating selection criteria that appropriately reflect the review question , review ers should consider which study design s to include . Ideally , review ers choose study design s that are most likely to produce valid results . For example , to answer questions about therapy or harm , review ers may want to include r and omized trials [ 7 ] because they provide more accurate estimates of benefit or harm than do cohort studies , casecontrol studies , and case series [ 8 ] . In reality , however , r and omized trials may not be conducted to address questions of harm [ 9 ] . Therefore , review ers need to consider which study design s are likely to be available to answer their question ; this information may necessitate modification of originally conceptualized selection criteria to incorporate observational ( nonexperimental ) studies . Specify Criteria Related to Type and Form of Publication Review ers also need to consider issues related to type and form of publication . Ideally , all of the relevant studies would be published as peer- review ed journal articles . However , some completed studies may be published only as abstract s , in non-peer- review ed form , or not at all . Review ers decide whether to include these incompletely reported studies when planning their literature search . By including all articles in various stages of publication and subjecting them to rigorous critical appraisal , review ers minimize the threat of publication bias ( the preferential reporting of studies with positive results ) [ 10 - 12 ] , which could generate misleading review s. Other studies may be reported more than once . To avoid over-representing duplicate studies in the review , investigators should plan to look for and exclude duplicate publications [ 13 ] . Finally , because studies may be published in different language s and because excluding studies published in different language s may bias the results of review s [ 14 , 15 ] , articles should be included , as appropriate , regardless of the language of publication ( translating as necessary ) . Limited time and re sources , however , may preclude such an approach . Construct and Pretest Selection Forms After deciding on selection criteria , review ers can prepare customized forms that contain checklists of the selection criteria ( Figure 1 ) . Using these forms can simplify the selection process , increase reliability , and provide a record of the judgments made about each study . After drafting form prototypes , review ers pretest these forms for clarity , ease of application , and reliability . To pretest the forms , two or more independent review ers typically apply them to a r and om sample of studies identified by the literature search . Review ers compare their results to identify sources of ambiguity and then revise the forms accordingly . If the revisions are substantial , this process may need to be repeated before the forms can be used . Figure 1 . Example of a form that might be developed for the selection of studies for a systematic review evaluating the efficacy of -blockers for secondary prevention of variceal bleeding .  Write a Detailed Protocol Having a selection protocol as part of a larger protocol for the entire review helps review ers in two ways . First , it provides a document that explicitly states the review question and the selection criteria , making the process accountable . Review ers can later return to the protocol for guidance in resolving disagreements about article selection . Second , the selection protocol identifies what work will be done , by whom , in what manner , when , and for what reason ; thus , it provides a mode of communication within the review team . When review ers have a very large sample of studies from which to select , they can simplify this task by review ing all of the titles , then the abstract s , and then the full articles , excluding studies that do not meet one or more selection criteria at each step . In doing so , review ers should record ( on the selection forms ) the reasons for exclusion . After review ers have selected studies for the systematic review , they will move to the next task of critical appraisal . This procedure also requires careful planning . Appraising Studies for Systematic Review s Review ers appraise the studies selected for review with three objectives in mind : 1 ) to underst and the validity of the studies , 2 ) to uncover reasons for differences among study results other than chance , and 3 ) to provide readers with sufficient information with which to judge for themselves the applicability of the systematic review to their clinical practice . To achieve these goals , review ers use the strategies outlined in Table 2 and Table 3 to carefully reexamine many important features of the primary studies . Table 3 . Planning Study Appraisal Examine Important Clinical Features Although the selection criteria for a systematic review define the population , interventions , and outcomes of interest , the appraisal process involves a detailed assessment of the patients ( for example , high , medium , or low risk ) , the study interventions ( for example , frequency , degree , and duration ) , and the outcome measurements ( for example , definitions and degree of surveillance ) BACKGROUND Baseline data collected on each patient at r and omisation in controlled clinical trials can be used to describe the population of patients , to assess comparability of treatment groups , to achieve balanced r and omisation , to adjust treatment comparisons for prognostic factors , and to undertake subgroup analyses . We assessed the extent and quality of such practice s in major clinical trial reports . METHODS A sample of 50 consecutive clinical -trial reports was obtained from four major medical journals during July to September , 1997 . We tabulated the detailed information on uses of baseline data by use of a st and ard form . FINDINGS Most trials presented baseline comparability in a table . These tables were often unduly large , and about half the trials inappropriately used significance tests for baseline comparison . Methods of r and omisation , including possible stratification , were often poorly described . There was little consistency over whether to use covariate adjustment and the criteria for selecting baseline factors for which to adjust were often unclear . Most trials emphasised the simple unadjusted results and covariate adjustment usually made negligible difference . Two-thirds of the reports presented subgroup findings , but mostly without appropriate statistical tests for interaction . Many reports put too much emphasis on subgroup analyses that commonly lacked statistical power . INTERPRETATION Clinical trials need a predefined statistical analysis plan for uses of baseline data , especially covariate-adjusted analyses and subgroup analyses . Investigators and journals need to adopt improved st and ards of statistical reporting , and exercise caution when drawing conclusions from subgroup findings BACKGROUND In the acute respiratory distress syndrome ( ARDS ) , positive end-expiratory pressure ( PEEP ) may decrease ventilator-induced lung injury by keeping lung regions open that otherwise would be collapsed . Since the effects of PEEP probably depend on the recruitability of lung tissue , we conducted a study to examine the relationship between the percentage of potentially recruitable lung , as indicated by computed tomography ( CT ) , and the clinical and physiological effects of PEEP . METHODS Sixty-eight patients with acute lung injury or ARDS underwent whole-lung CT during breath-holding sessions at airway pressures of 5 , 15 , and 45 cm of water . The percentage of potentially recruitable lung was defined as the proportion of lung tissue in which aeration was restored at airway pressures between 5 and 45 cm of water . RESULTS The percentage of potentially recruitable lung varied widely in the population , accounting for a mean ( + /-SD ) of 13+/-11 percent of the lung weight , and was highly correlated with the percentage of lung tissue in which aeration was maintained after the application of PEEP ( r2=0.72 , P<0.001 ) . On average , 24 percent of the lung could not be recruited . Patients with a higher percentage of potentially recruitable lung ( greater than the median value of 9 percent ) had greater total lung weights ( P<0.001 ) , poorer oxygenation ( defined as a ratio of partial pressure of arterial oxygen to fraction of inspired oxygen ) ( P<0.001 ) and respiratory-system compliance ( P=0.002 ) , higher levels of dead space ( P=0.002 ) , and higher rates of death ( P=0.02 ) than patients with a lower percentage of potentially recruitable lung . The combined physiological variables predicted , with a sensitivity of 71 percent and a specificity of 59 percent , whether a patient 's proportion of potentially recruitable lung was higher or lower than the median . CONCLUSIONS In ARDS , the percentage of potentially recruitable lung is extremely variable and is strongly associated with the response to PEEP Objective We examined the effect on survival of prone positioning as an early and continuous treatment in ARDS patients already treated with protective ventilation . Design and setting Open r and omized controlled trial in 17 medical-surgical ICUs . Patients Forty mechanically ventilated patients with early and refractory ARDS despite protective ventilation in the supine position . Interventions Patients were r and omized to remain supine or be moved to early ( within 48 h ) and continuous ( ≥ 20 h/day ) prone position until recovery or death . The trial was prematurely stopped due to a low patient recruitment rate . Measurements and results Clinical characteristics , oxygenation , lung pressures , and hemodynamics were monitored . Need for sedation , complications , length of MV , ICU , and hospital stays , and outcome were recorded . PaO2/FIO2 tended to be higher in prone than in supine patients after 6 h ( 202 ± 78 vs. 165 ± 70 mmHg ) ; this difference reached statistical significance on day 3 ( 234 ± 85 vs. 159 ± 78 ) . Prone-related side effects were minimal and reversible . Sixty-day survival reached the targeted 15 % absolute increase in prone patients ( 62 % vs. 47 % ) but failed to reach significance due to the small sample . Conclusions Our study adds data that reinforce the suggestion of a beneficial effect of early continuous prone positioning on survival in ARDS patients Objective : The improvement in oxygenation with prone positioning is not persistent when patients with acute respiratory distress syndrome ( ARDS ) are turned supine . High‐frequency oscillatory ventilation ( HFOV ) aims to maintain an open lung volume by the application of a constant mean airway pressure . The aim of this study was to show that HFOV is able to prevent the impairment in oxygenation when ARDS patients are turned back from the prone to the supine position . Design : Prospect i ve , comparative r and omized study . Setting : A medical intensive care unit . Patients : Forty‐three ARDS patients with a Pao2/Fio2 ratio < 150 at positive end‐expiratory pressure ≥5 cm H2O . Interventions : After an optimization period , the patients were assigned to one of three groups : a ) conventional lung‐protective mechanical ventilation in the prone position ( 12 hrs ) followed by a 12‐hr period of conventional lung‐protective mechanical ventilation in the supine position ( CVprone‐CVsupine ) ; b ) conventional lung‐protective mechanical ventilation in the supine position ( 12 hrs ) followed by HFOV in the supine position ( 12 hrs ) ( CVsupine‐HFOVsupine ) ; or c ) conventional lung‐protective mechanical ventilation in the prone position ( 12 hrs ) followed by HFOV in the supine position ( CVprone‐HFOVsupine group ) . Measurements and Main Results : Pao2/Fio2 ratio was higher at the end of the study period in the CVprone‐HFOVsupine group than in the CVprone‐CVsupine group ( p < .02 ) . Venous admixture at the end of the study period was lower in the CVprone‐HFOVsupine group than in the two other groups . Conclusions : HFOV maintained the improvement in oxygenation related to prone positioning when ARDS patients were returned to the supine position CONTEXT In uncontrolled clinical studies , prone positioning appeared to be safe and to improve oxygenation in pediatric patients with acute lung injury . However , the effect of prone positioning on clinical outcomes in children is not known . OBJECTIVE To test the hypothesis that at the end of 28 days infants and children with acute lung injury treated with prone positioning would have more ventilator-free days than those treated with supine positioning . DESIGN , SETTING , AND PATIENTS Multicenter , r and omized , controlled clinical trial conducted from August 28 , 2001 , to April 23 , 2004 , of 102 pediatric patients from 7 US pediatric intensive care units aged 2 weeks to 18 years who were treated with supine vs prone positioning .  R and omization was concealed and group assignment was not blinded . INTERVENTION Patients were r and omized to either supine or prone positioning within 48 hours of meeting acute lung injury criteria , with those patients in the prone group being positioned within 4 hours of r and omization and remaining prone for 20 hours each day during the acute phase of their illness for a maximum of 7 days , after which they were positioned supine . Both groups were treated using lung protective ventilator and sedation protocol s , extubation readiness testing , and hemodynamic , nutrition , and skin care guidelines . MAIN OUTCOME MEASURE Ventilator-free days to day 28 . RESULTS The trial was stopped at the planned interim analysis on the basis of the prespecified futility stopping rule . There were no differences in the number of ventilator-free days between the 2 groups ( mean [ SD ] , 15.8 [ 8.5 ] supine vs 15.6 [ 8.6 ] prone ; mean difference , -0.2 days ; 95 % CI , -3.6 to 3.2 ; P = .91 ) . After controlling for age , Pediatric Risk of Mortality III score , direct vs indirect acute lung injury , and mode of mechanical ventilation at enrollment , the adjusted difference in ventilator-free days was 0.3 days ( 95 % CI , -3.0 to 3.5 ; P = .87 ) . There were no differences in the secondary end points , including proportion alive and ventilator-free on day 28 ( P = .45 ) , mortality from all causes ( P>.99 ) , the time to recovery of lung injury ( P = .78 ) , organ-failure-free days ( P = .88 ) , and cognitive impairment ( P = .16 ) or overall functional health ( P = .12 ) at hospital discharge or on day 28 . CONCLUSION Prone positioning does not significantly reduce ventilator-free days or improve  other  clinical outcomes in pediatric patients with acute lung injury CONTEXT A recent trial showed that placing patients with acute lung injury in the prone position did not increase survival ; however , whether those results hold true for patients with hypoxemic acute respiratory failure ( ARF ) is unclear . OBJECTIVE To determine whether prone positioning improves mortality in ARF patients . DESIGN , SETTING , AND PATIENTS Prospect i ve , unblinded , multicenter controlled trial of 791 ARF patients in 21 general intensive care units in France using concealed r and omization conducted from December 14 , 1998 , through December 31 , 2002 . To be included , patients had to be at least 18 years , hemodynamically stable , receiving mechanical ventilation , and intubated and had to have a partial pressure of arterial oxygen ( PaO2 ) to fraction of inspired oxygen ( FIO2 ) ratio of 300 or less and no contraindications to lying prone . INTERVENTIONS Patients were r and omly assigned to prone position placement ( n = 413 ) , applied as early as possible for at least 8 hours per day on st and ard beds , or to supine position placement ( n = 378 ) . MAIN OUTCOME MEASURES The primary end point was 28-day mortality ; secondary end points were 90-day mortality , duration of mechanical ventilation , incidence of ventilator-associated pneumonia ( VAP ) , and oxygenation . RESULTS The 2 groups were comparable at r and omization . The 28-day mortality rate was 32.4 % for the prone group and 31.5 % for the supine group ( relative risk [ RR ] , 0.97 ; 95 % confidence interval [ CI ] , 0.79 - 1.19 ; P = .77 ) . Ninety-day mortality for the prone group was 43.3 % vs 42.2 % for the supine group ( RR , 0.98 ; 95 % CI , 0.84 - 1.13 ; P = .74 ) . The mean ( SD ) duration of mechanical ventilation was 13.7 ( 7.8 ) days for the prone group vs 14.1 ( 8.6 ) days for the supine group ( P = .93 ) and the VAP incidence was 1.66 vs 2.14 episodes per 100- patients days of intubation , respectively ( P = .045 ) . The PaO2/FIO2 ratio was significantly higher in the prone group during the 28-day follow-up . However , pressure sores , selective intubation , and endotracheal tube obstruction incidences were higher in the prone group . CONCLUSIONS This trial demonstrated no beneficial outcomes and some safety concerns associated with prone positioning . For patients with hypoxemic ARF , prone position placement may lower the incidence of VAP PURPOSE This paper describes the methodology of a clinical trial of prone positioning in pediatric patients with acute lung injury ( ALI ) . Nonr and omized studies suggest that prone positioning improves oxygenation in patients with ALI/acute respiratory distress syndrome without the risk of serious iatrogenic injury . It is not known if these improvements in oxygenation result in improvements in clinical outcomes . A clinical trial was needed to answer this question . MATERIAL S AND METHODS The pediatric prone study is a multicenter , r and omized , noncrossover , controlled clinical trial . The trial is design ed to test the hypothesis that at the end of 28 days , children with ALI treated with prone positioning will have more ventilator-free days than children treated with supine positioning . Secondary end points include the time to recovery of lung injury , organ failure-free days , functional outcome , adverse events , and mortality from all causes .  Pediatric patients , 42 weeks postconceptual age to 18 years of age , are enrolled within 48 hours of meeting ALI criteria . Patients r and omized to the prone group are positioned prone within 4 hours of r and omization and remain prone for 20 hours each day during the acute phase of their illness for a maximum of 7 days . Both groups are managed according to ventilator protocol , extubation readiness testing , and sedation protocol s and hemodynamic , nutrition , and skin care guidelines . CONCLUSIONS This paper describes the process , multidisciplinary input , and procedures used to support the design of the clinical trial , as well as the challenges faced by the clinical scientists during the conduct of the clinical trial Objective : To describe the effects of prone positioning on airway management , mechanical ventilation , enteral nutrition , pain and sedation management , and staff utilization in infants and children with acute lung injury . Design : Secondary analysis of data collected in a multiple-center , r and omized , controlled clinical trial of supine vs. prone positioning . Setting : Seven pediatric intensive care units located in the United States . Patients : One hundred and two pediatric patients ( 51 prone and 51 supine ) with acute lung injury . Interventions : Patients r and omized to the supine group remained supine . Patients r and omized to the prone group were positioned prone per protocol during the acute phase of their illness for a maximum of 7 days . Both groups were managed using ventilator and sedation protocol s and nutrition and skin care guidelines . Measurements and Main Results : Airway management and mechanical ventilatory variables before and after repositioning , enteral nutrition management , pain and sedation management , staff utilization , and adverse event data were collected for up to 28 days after enrollment . There were a total of 202 supine-prone-supine cycles . There were no differences in the incidence of endotracheal tube leak between the two groups ( p = .30 ) . Per protocol , 95 % of patients remained connected to the ventilator during repositioning . The inadvertent extubation rate was 0.85 for the prone group and 1.03 for the supine group per 100 ventilator days ( p = 1.00 ) . There were no significant differences in the initiation of trophic ( p = .24 ) , advancing ( p = .82 ) , or full enteral feeds ( p = .80 ) between the prone and supine groups ; in the average pain ( p = .81 ) and sedation ( p = .18 ) scores during the acute phase ; and in the amount of comfort medications received between the two groups ( p = .91 ) . There were no critical events during a turn procedure . While prone , two patients experienced an obstructed endotracheal tube . One patient , supported on high-frequency oscillatory ventilation , experienced persistent hypercapnea when prone and was withdrawn from the study . The occurrence of pressure ulcers was similar between the two groups ( p = .71 ) . Compared with the supine group , more staff ( p ≤ .001 ) and more time were necessary to reposition patients in the prone group . Conclusions : Our data show that prone positioning can be safely performed in critically ill pediatric patients and that these patients can be safely managed while in the prone position for prolonged periods of time In 12 patients with severe adult respiratory distress syndrome ( ARDS ) ,  pulmonary gas exchange and hemodynamics were evaluated before , during , and after a 2-h period of pressure-controlled mechanical ventilation with the patient in the prone position .  Ventilation-perfusion relationships ( VA/Q ) were assessed by a multiple inert gas elimination technique . Pressure-controlled mechanical ventilation in the prone position result ed in an overall increase ( p < or = 0.05 ) of arterial oxygenation after 120 min ( 98.4 + /- 50.3 to 146.2 + /- 94.9 mm Hg ) . Whereas eight patients revealed an improvement of PaO2 of more than 10 mm Hg after 30 min in the prone position ( responders ) , four patients reacted to positional changes with a deterioration of  arterial oxygenation ( nonresponders ) . Data about the continuous distribution of ventilation-perfusion ratios revealed that in the responder group positioning caused a decrease of shunt perfusion of 11 + /- 5 % and a concomitant increase of normal VA/Q by 12 + /- 4 % after 30 min . There was no change demonstrable within low VA/Q areas . Returning the patient to the supine position reversed the improvement in gas exchange . The nonresponder group did not show any significant alteration in the distribution of VA/Q during the study . We concluded that improvement of oxygenation during pressure-controlled mechanical ventilation in the prone position is due to a shift of blood flow away from shunt regions , thus increasing areas with normal VA/Q. This redistribution of blood flow is most likely caused by a recruitment of previously ateletatic but nondiseased areas induced by altered gravitational forces Abstract . Objective : Comatose patients frequently exhibit pulmonary function worsening , especially in cases of pulmonary infection . It appears to have a deleterious effect on neurologic outcome . We therefore conducted a r and omized trial to determine whether daily prone positioning would prevent lung worsening in these patients . Design : Prospect i ve , r and omized , controlled study . Setting : Sixteen-bed intensive care unit . Patients : Fifty-one patients who required invasive mechanical ventilation because of coma with Glascow coma scores of 9 or less . Interventions : In the prone position ( PP ) group : prone positioning for 4 h once daily until the patients could get up to sit in an armchair ; in the supine position ( SP ) group : supine positioning . Measurements and results : The primary end point was the incidence of lung worsening defined by an increase in the Lung Injury Score of at least 1 point since the time of r and omization . The secondary end point was the incidence of ventilator-associated pneumonia ( VAP ) . A total of 25 patients were r and omly assigned to the PP group and 26 patients to the SP group . The characteristics of the patients from the two groups were similar at r and omization . The incidence of lung worsening was lower in the PP group ( 12 % ) than in the SP group ( 50 % ) ( p=0.003 ) . The incidence of VAP was 20 % in the PP group and 38.4 % in the SP group ( p=0.14 ) . There was no serious complication attributable to prone positioning , however , there was a significant increase of intracranial pressure in the PP . Conclusion : In a selected population of comatose ventilated patients , daily prone positioning reduced the incidence of lung worsening There is little information on long-term outcome after acute respiratory distress syndrome ( ARDS ) . We measured quality -adjusted survival in the first year after ARDS in a prospect i ve cohort ( n = 200 ) . All patients met traditional criteria for ARDS . Patients with sepsis and acute nonpulmonary organ dysfunction at presentation were excluded . The cohort was healthy before onset of ARDS as evidence d by high functional status ( mean Karnofsky Performance Status index : 82.2/100 where > /= 80 = able to perform normal activities independently ) and minimal comorbid illness ( mean Charlson-Deyo comorbidity score : 0.32/17 where 0 = absence of chronic illness ) . We determined quality -adjusted life-years ( QALYs ) using the Quality of Well-being ( QWB ) scale ( 0 to 1 scale where 1 = optimal well-being ) , measured at 6 and 12 mo . Survival was 69.5 + /- 5.0 % at 1 month , fell to 55.7 + /- 3.7 % at 6 mo , and did not change at 12 mo , yielding a survival of 59 life-years in the first year per 100 patients with ARDS . QWB was low at 6 and 12 mo ( 0.59 + /- 0.015 and 0.60 + /- 0.015 ) , yielding a quality -adjusted survival of 36 QALYs per 100 patients ( sensitivity range : 21 to 46 QALYs ) . We conclude that ARDS developing in previously healthy patients is associated with poor quality -adjusted survival . These data are important for cost-effectiveness analyses and long-term care Objective To determine whether gas exchange response to a first prone position session can predict patient outcome in hypoxemic acute respiratory failure . Methods Data from a previous multicenter r and omized controlled trial were retrospectively analyzed for relationship between PaO2/FIO2 ratio and PaCO2 changes during the first 8-h prone position session to day 28 mortality rate ; 370 prone position sessions were analyzed .  Arterial blood gas was measured in supine position before proning and in prone position at the end of the session . Gas exchange improvement was defined as increase in the PaO2/FIO2 ratio of more than 20 % ( PaO2R ) or decrease in PaCO2 of more than 1 mmHg (PaCO2R).Main results The 28-day mortality rate was 26.5 % in PaO2R – PaCO2R , 31.7 % in PaO2R – PaCO2NR , 38.9 % in PaO2NR – PaCO2R , and 43 % in PaO2NR – PaCO2NR ( log-rank 14.02 , p = 0.003 ) . In a Cox proportional hazards model the gas exchange response was a significant predictor to patient outcome with a 82.5 % increase in risk of death in the case of PaO2NR – PaCO2R or PaO2NR – PaCO2NR , relative to the gas exchange improvement response ( odds ratio 1.825 ) . However , after adjusting for the difference in oxygenation between day 2 and day 1 the gas exchange response does no longer reach significance . Conclusion In patients with hypoxemic acute respiratory failure initial improvement in gas exchange in the first PP session was associated with a better outcome , but this association disappeared when the change in oxygenation from day 1 to day 2 was taken into account , suggesting that underlying illness was the most important predictor of mortality in this patient population BACKGROUND / PURPOSE Acute respiratory distress syndrome ( ARDS ) is a serious disorder of intensive care unit patients . We evaluated the safety of continuous prone position ventilation ( PRONE ) and its effects on oxygenation and plasma cytokine concentrations in patients with ARDS caused by severe community-acquired pneumonia ( CAP ) . METHODS This was a prospect i ve observational clinical study conducted in a respiratory intensive care unit of a 1200-bed medical center in central Taiwan . Twenty-two patients with severe CAP and ARDS were included . They were treated by traditional supine ventilation ( SUPINE , n = 11 ) or PRONE ( n = 11 ) if they met the criteria for ARDS . Patients in the PRONE group were ventilated in prone position continuously for at least 72 hours . Plasma cytokines were collected and analyzed at baseline , 24 hours and 72 hours after enrolment . Serial PaO2/FiO2 and complications were evaluated . RESULTS Complications associated with PRONE were minor and self-limited . PRONE had higher PaO2/FiO2 ratio than SUPINE did at 48 hours after enrolment . The levels of plasma IL-6 concentration declined significantly with time in the PRONE group ( p = 0.011 ) . The levels of plasma IL-6 concentration at enrolment , 24 hours and 72 hours after enrolment also predicted the 14th day mortality of all patients . CONCLUSION PRONE was a safe and effective maneuver for improving oxygenation in patients with severe CAP and ARDS . PRONE also influenced IL-6 expression in patients with severe CAP BACKGROUND Acute lung injury is a critical illness syndrome consisting of acute hypoxemic respiratory failure with bilateral pulmonary infiltrates that are not attributed to left atrial hypertension . Despite recent advances in our underst and ing of the mechanism and treatment of acute lung injury , its incidence and outcomes in the United States have been unclear . METHODS We conducted a prospect i ve , population -based , cohort study in 21 hospitals in and around King County , Washington , from April 1999 through July 2000 , using a vali date d screening protocol to identify patients who met the consensus criteria for acute lung injury . RESULTS A total of 1113 King County residents undergoing mechanical ventilation met the criteria for acute lung injury and were 15 years of age or older . On the basis of this figure , the crude incidence of acute lung injury was 78.9 per 100,000 person-years and the age-adjusted incidence was 86.2 per 100,000 person-years . The in-hospital mortality rate was 38.5 percent . The incidence of acute lung injury increased with age from 16 per 100,000 person-years for those 15 through 19 years of age to 306 per 100,000 person-years for those 75 through 84 years of age . Mortality increased with age from 24 percent for patients 15 through 19 years of age to 60 percent for patients 85 years of age or older ( P<0.001 ) . We estimate that each year in the United States there are 190,600 cases of acute lung injury , which are associated with 74,500 deaths and 3.6 million hospital days . CONCLUSIONS Acute lung injury has a substantial impact on public health , with an incidence in the United States that is considerably higher than previous reports have suggested BACKGROUND Although placing patients with acute respiratory failure in a prone ( face down ) position improves their oxygenation 60 to 70 percent of the time , the effect on survival is not known . METHODS In a multicenter , r and omized trial , we compared conventional treatment ( in the supine position ) of patients with acute lung injury or the acute respiratory distress syndrome with a predefined strategy of placing patients in a prone position for six or more hours daily for 10 days . We enrolled 304 patients , 152 in each group . RESULTS The mortality rate was 23.0 percent during the 10-day study period , 49.3 percent at the time of discharge from the intensive care unit , and 60.5 percent at 6 months . The relative risk of death in the prone group as compared with the supine group was 0.84 at the end of the study period ( 95 percent confidence interval , 0.56 to 1.27 ) , 1.05 at the time of discharge from the intensive care unit ( 95 percent confidence interval , 0.84 to 1.32 ) , and 1.06 at six months ( 95 percent confidence interval , 0.88 to 1.28 ) . During the study period the mean ( + /-SD ) increase in the ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen , measured each morning while patients were supine , was greater in the prone than the supine group ( 63.0+/-66.8 vs. 44.6+/-68.2 , P=0.02 ) . The incidence of complications related to positioning ( such as pressure sores and accidental extubation ) was similar in the two groups . CONCLUSIONS Although placing patients with acute respiratory failure in a prone position improves their oxygenation , it does not improve survival OBJECTIVES A bronchial secretion draining effect is frequently suggested as a mechanism for oxygenation improvement during prone positioning ( PP ) in patients with acute respiratory distress syndrome ( ARDS ) . Nevertheless , it has never really been evaluated . The aim of this study was to search for an interrelationship between the volume of the bronchial secretion and the improvement of the PaO2/FIO2 ratio during prone positioning , with NO inhalation or not . STUDY DESIGN Open prospect i ve clinical study . PATIENTS The study included 15 consecutive patients with severe ARDS ( PaO2/FIO2 < 200 after alveolar recruitment , Murray score > 2.5 ) . METHODS They were returned to the prone position for 4 hours ( h0-h4 ) combined with an inhalation of 5 ppm NO during 1 hour ( h2-h3 ) . Tracheal suction were performed hourly between h-2 and h6 and weighed on a precision scale from h-1 to h6 . Haemodynamic , blood gas and respiratory compliance were recorded at h0 , h2 , h3 , h4 and h6 . RESULTS No significant haemodynamic changes were observed in the various phases . Compared with the baseline condition at h0 , PP and PP + NO respectively improved PaO2/FIO2 by 102 + /- 62 % at h2 ( P < 0.005 ) and 156 + /- 79 % at h3 ( P < 0.005/h0 and < 0.01/h2 ) . 14/15 patients responded to PP and 15/15 to PP + NO ( gain in PaO2/FIO2 > 10 % ) . Concerning secretions , we collected 3.0 + /- 7.5 g , 4.4 + /- 6.1 g , 1.7 + /- 1.4 g and 1.7 + /- 1.6 between h-2 and h0 , h0 and h2 , h2 and h4 , h4 and h6 . Individual assessment s showed no relationship between the PaO2/FIO2 evolution at any time and the quantity of secretions obtained during the first 2 hours in the prone position . Six patients presented secretions of less than 1 g between h0 and h2 , and for whom the improvement in oxygenation was higher than average ( 115 + /- 53 % at h2 ) . CONCLUSION In patients with little or moderate secretions , the improvement observed in oxygenation , with or without NO , does not depend on their volume RATIONALE Little is known about the long-term outcomes and costs of survivors of acute respiratory distress syndrome ( ARDS ) . OBJECTIVES To describe functional and quality of life outcomes , health care use , and costs of survivors of ARDS 2 yr after intensive care unit ( ICU ) discharge . METHODS We recruited a cohort of ARDS survivors from four academic tertiary care ICUs in Toronto , Canada , and prospect ively monitored them from ICU admission to 2 yr after ICU discharge .  MEASUREMENTS Clinical and functional outcomes , health care use , and direct medical costs . RESULTS Eighty-five percent of patients with ARDS discharged from the ICU survived to 2 yr ; overall 2-yr mortality was 49 % . At 2 yr , survivors continued to have exercise limitation although 65 % had returned to work . There was no statistically significant improvement in health-related quality of life as measured by Short-Form General Health Survey between 1 and 2 yr , although there was a trend toward better physical role at 2 yr ( p = 0.0586 ) . Apart from emotional role and mental health , all other domains remained below that of the normal population . From ICU admission to 2 yr after ICU discharge , the largest portion of health care costs for a survivor of ARDS was the initial hospital stay , with ICU costs accounting for 76 % of these costs . After the initial hospital stay , health care costs were related to hospital readmissions and inpatient rehabilitation . CONCLUSIONS Survivors of ARDS continued to have functional impairment and compromised health-related quality of life 2 yr after discharge from the ICU . Health care use and costs after the initial hospitalization were driven by hospital readmissions and inpatient rehabilitation Objective To determine whether gas exchange improvement in response to the prone position is associated with an improved outcome in acute lung injury (ALI)/acute respiratory distress syndrome ( ARDS ) . Design Retrospective analysis of patients in the pronation arm of a controlled r and omized trial on prone positioning and patients enrolled in a previous pilot study of the prone position . Setting Twenty-eight Italian and two Swiss intensive care units . Patients We studied 225 patients meeting the criteria for ALI or ARDS . Interventions Patients were in prone position for 10 days for 6 hrs/day if they met ALI/ARDS criteria when assessed each morning . Respiratory variables were recorded before and after 6 hrs of pronation with unchanged ventilatory setting s. Measurements and Main Results We measured arterial blood gas alterations to the first pronation and the 28-day mortality rate . The independent risk factors for death in the general population were the Pao2/Fio2 ratio ( odds ratio , 0.992 ; confidence interval , 0.986–0.998 ) , the minute ventilation/Paco2 ratio ( odds ratio , 1.003 ; confidence interval , 1.000–1.006 ) , and the concentration of plasma creatinine ( odds ratio , 1.385 ; confidence interval , 1.116–1.720 ) . Pao2 responders ( defined as the patients who increased their Pao2/Fio2 by ≥20 mm Hg , 150 patients , mean increase of 100.6 ± 61.6 mm Hg [ 13.4 ± 8.2 kPa ] ) had an outcome similar to the nonresponders ( 59 patients , mean decrease −6.3 ± 23.7 mm Hg [ −0.8 ± 3.2 kPa ] ; mortality rate 44 % and 46 % , respectively ; relative risk , 1.04 ; confidence interval , 0.74–1.45 , p = .65 ) . The Paco2 responders ( defined as patients whose Paco2 decreased by ≥1 mm Hg , 94 patients , mean decrease −6.0 ± 6 mm Hg [ −0.8 ± 0.8 kPa ] ) had an improved survival when compared with nonresponders ( 115 patients , mean increase 6 ± 6 mm Hg [ 0.8 ± 0.8 kPa ] ; mortality rate 35.1 % and 52.2 % , respectively ; relative risk , 1.48 ; confidence interval , 1.07–2.05 , p = .01 ) . Conclusion ALI/ARDS patients who respond to prone positioning with reduction of their Paco2 show an increased survival at 28 days . Improved efficiency of alveolar ventilation ( decreased physiologic deadspace ratio ) is an important marker of patients who will survive acute respiratory failure OBJECTIVE The ability to accurately identify articles about therapy in large bibliographic data bases such as EMBASE is important for research ers and clinicians . Our study aim ed to develop optimal search strategies for detecting sound treatment studies in EMBASE in the year 2000 . METHODS H and search es of journals were compared with retrievals from EMBASE for c and i date search strategies . Six trained research assistants review ed fifty-five journals indexed in EMBASE and rated articles using purpose and quality indicators . C and i date search strategies were developed for identifying treatment articles and then tested , and the retrievals were compared with the h and - search data . The operating characteristics of the strategies were calculated . RESULTS Three thous and eight hundred fifty articles were original studies on treatment , of which 1,256 ( 32.6 % ) were method ologically sound . Combining search terms revealed a top performing strategy ( r and om:.tw . OR clinical trial:.mp . OR exp health care quality ) with sensitivity of 98.9 % and specificity of 72.0 % . Maximizing specificity , a top performing strategy ( double-blind:.mp . OR placebo:.tw . OR blind : .tw . ) achieved a value over 96.0 % , but with compromised sensitivity at 51.7 % . A 3-term strategy achieved the best optimization of sensitivity and specificity ( r and om:.tw . OR placebo:.mp . OR double-blind:.tw . ) , with both these values over 92.0 % . CONCLUSION Search strategies can achieve high performance for retrieving sound treatment studies in EMBASE BACKGROUND In a prospect i ve r and omized trial the effect of prone positioning on the duration of mechanical ventilation was evaluated in multiple trauma patients and was compared with patients ventilated in supine position . METHOD Multiple trauma patients of the intensive care units of two university hospitals were considered eligible if they met the criteria for acute lung injury or the acute respiratory distress syndrome . Patients in the prone group ( N = 21 ) were kept prone for at least eight hours and a maximum of 23 hours per day . Prone positioning was continued until a PaO2:FiO2 ratio of more than 300 was present in prone as well as supine position over a period of 48 hours . Patients in the supine group ( N = 19 ) were positioned according to st and ard care guidelines . RESULTS The duration of ventilatory support did not differ significantly ( 30 + /- 17 days in the prone group and 33 + /- 23 days in the supine group ) . Worst case analysis ( death and deterioration of gas exchange ) displayed ventilatory support for 41 + /- 29 days in the prone group and 61 + /- 35 days in the supine group ( p = 0.06 ) . The PaO2:FiO2 ratio increased significantly more in the prone group in the first four days ( p = 0.03 ) . The prevalence of Acute Respiratory Distress Syndrome ( ARDS ) following acute lung injury ( p = 0.03 ) and the prevalence of pneumonia ( p = 0.048 ) were reduced also . One patient in the prone and three patients in the supine group died due to multi organ failure ( p = 0.27 ) . CONCLUSIONS Intermittent prone positioning was not able to reduce the duration of mechanical ventilation in this limited number of patients . However the oxygenation improved significantly over the first four days of treatment , and the prevalence of ARDS and pneumonia were reduced RATIONALE Ventilation in the prone position for about 7 h/d in patients with acute respiratory distress syndrome ( ARDS ) , acute lung injury , or acute respiratory failure does not decrease mortality . Whether it is beneficial to administer prone ventilation early , and for longer periods of time , is unknown . METHODS We enrolled 136 patients within 48 h of tracheal intubation for severe ARDS , 60 r and omized to supine and 76 to prone ventilation .  Guidelines were established for ventilator setting s and weaning . The prone group was targeted to receive continuous prone ventilation treatment for 20 h/d . RESULTS The intensive care unit mortality was 58 % ( 35/60 ) in the patients ventilated supine and 43 % ( 33/76 ) in the patients ventilated prone ( p = 0.12 ) . The latter had a higher simplified acute physiology score II at inclusion . Multivariate analysis showed that simplified acute physiology score II at inclusion ( odds ratio [ OR ] , 1.07 ; p < 0.001 ) , number of days elapsed between ARDS diagnosis and inclusion ( OR , 2.83 ; p < 0.001 ) , and r and omization to supine position ( OR , 2.53 ; p = 0.03 ) were independent risk factors for mortality . A total of 718 turning procedures were done , and prone position was applied for a mean of 17 h/d for a mean of 10 d. A total of 28 complications were reported , and most were rapidly reversible . CONCLUSION Prone ventilation is feasible and safe , and may reduce mortality in patients with severe ARDS when it is initiated early and applied for most of the day BACKGROUND Some r and omised controlled trials ( RCTs ) done in German-speaking Europe are published in international English- language journals and others in national German- language journals . We assessed whether authors are more likely to report trials with statistically significant results in English than in German . METHODS We studied pairs of RCT reports , matched for first author and time of publication , with one report published in German and the other in English . Pairs were identified from reports round in a manual search of five leading German- language journals and from reports published by the same authors in English found on Medline .  Quality of methods and reporting were assessed with two different scales by two investigators who were unaware of authors ' identities , affiliations , and other characteristics of trial reports . Main study endpoints were selected by two investigators who were unaware of trial results . Our main outcome was the number of pairs of studies in which the levels of significance ( shown by p values ) were discordant . FINDINGS 62 eligible pairs of reports were identified but 19 ( 31 % ) were excluded because they were duplicate publications . A further three pairs ( 5 % ) were excluded because no p values were given . The remaining 40 pairs were analysed . Design characteristics and quality features were similar for reports in both language s. Only 35 % of German- language articles , compared with 62 % of English- language articles , reported significant ( p < 0.05 ) differences in the main endpoint between study and control groups ( p = 0.002 by McNemar 's test ) . Logistic regression showed that the only characteristic that predicted publication in an English- language journal was a significant result . The odds ratio for publication of trials with significant results in English was 3.75 ( 95 % CI 1.25 - 11.3 ) . INTERPRETATION Authors were more likely to publish RCTs in an English- language journal if the results were statistically significant . English language bias may , therefore , be introduced in review s and meta-analyses if they include only trials reported in English . The effort of the Cochrane Collaboration to identify as many controlled trials as possible , through the manual search of many medical journals published in different language s will help to reduce such bias Observational studies of high-frequency oscillatory ventilation in adults with the acute respiratory distress syndrome have demonstrated improvements in oxygenation . We design ed a multicenter , r and omized , controlled trial comparing the safety and effectiveness of high-frequency oscillatory ventilation with conventional ventilation in adults with acute respiratory distress syndrome ; 148 adults with acute respiratory distress syndrome ( Pa(O2)/fraction of inspired oxygen < or= 200 mm Hg on 10 or more cm H2O positive end-expiratory pressure ) were r and omized to high-frequency oscillatory ventilation  ( n = 75 ) or conventional ventilation ( n = 73 ) . Applied mean airway pressure was significantly higher in the high-frequency oscillation group compared with the conventional ventilation group throughout the first 72 hours ( p = 0.0001 ) . The high-frequency oscillation group showed early ( less than 16 hours ) improvement in Pa(O2)/fraction of inspired oxygen compared with the conventional ventilation group ( p = 0.008 ) ; however , this difference did not persist beyond 24 hours . Oxygenation index decreased similarly over the first 72 hours in both groups . Thirty-day mortality was 37 % in the high-frequency oscillation group and was 52 % in the conventional ventilation group ( p = 0.102 ) . The percentage of patients alive without mechanical ventilation at Day 30 was 36 % and 31 % in the high-frequency oscillation and conventional ventilation groups , respectively ( p = 0.686 ) . There were no significant differences in hemodynamic variables , oxygenation failure , ventilation failure , barotraumas , or mucus plugging between treatment groups . We conclude that high-frequency oscillation is a safe and effective mode of ventilation for the treatment of acute respiratory distress syndrome in adults Objective Although the prone position has been reported to improve arterial oxygenation in patients with acute respiratory distress syndrome , there have been no reports on its efficacy in patients with hypoxemia after transthoracic esophagectomy with three-field lymphadenectomy . This study was undertaken to assess the efficacy of the prone position on hypoxemia after three-field lymphadenectomy for thoracic esophageal carcinoma . Design Prospect i ve r and omized clinical study . Setting General intensive care unit at a university hospital . Interventions and Measurements Sixteen patients who underwent three-field lymphadenectomy and showed hypoxemia ( Pao2/Fio2 ratios of < 200 under positive end-expiratory pressure of > 5 cm H2O ) on the fifth postoperative day were r and omly assigned to prone ( eight patients ) and nonprone ( eight patients ) groups . Prone position for 6 hrs was carried out for four consecutive days . The Pao2/Fio2 ratio , the duration of ventilatory support , and length of stay , were measured . Results Oxygenation : The Pao2/Fio2 ratio markedly increased by 32 % ± 22 % in seven of eight patients ( p < .05 ) when the patients were moved from the supine to the prone position . The Pao2/Fio2 ratio after the fourth prone position ( 238 ± 55 , p < .05 ) was significantly higher than that before the first trial of prone position ( 166 ± 25 ) in these seven patients . Duration of ventilatory support and intensive care unit length of stay : Both the ventilation period ( 11.6 ± 2.2 vs. 14.0 ± 1.6 days , p = .0029 ) and the length of stay in the intensive care unit ( 12.8 ± 4.4 vs. 17.2 ± 3.4 days , p = .0032 ) were significantly shorter in the prone group compared with the nonprone group . The Pao2/Fio2 ratio at the time of cessation of prone positioning was significantly higher than the corresponding value in the nonprone group . Conclusion In hypoxemic patients after three-field lymphadenectomy , the prone position improved arterial oxygenation without any deleterious effects . The beneficial effect of the prone position is possibly attributable to opening of the bronchi obstructed by secretions
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 (PaO2)/inspired fraction of oxygen ( FiO2 ) < 100 mmHg ] compared with moderate hypoxemia ( 100 mmHg ≤ PaO2/FiO2 ≤ 300 mmHg ) .