human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: RATIONALE The 1994 American European Consensus Committee definitions of acute lung injury ( ALI ) and the acute respiratory distress syndrome ( ARDS ) have not been applied systematic ally in the pediatric population . OBJECTIVES The purpose of this study was to evaluate prospect ively the epidemiology and clinical risk factors associated with death and prolonged mechanical ventilation in all pediatric patients admitted to two large , pediatric intensive care units with ALI/ARDS using Consensus criteria . METHODS All pediatric patients meeting Consensus Committee definitions for ALI were prospect ively identified and included in a relational data base . MEASUREMENTS AND MAIN RESULTS There were 328 admissions for ALI/ARDS with a mortality of 22 % . Multivariate logistic regression analyses revealed ( 1 ) the initial severity of oxygenation defect , as measured by the Pa(O2)/FI(O2 ) ratio ; ( 2 ) the presence of nonpulmonary and non- central nervous system ( CNS ) organ dysfunction ; and ( 3 ) the presence of CNS dysfunction were independently associated with mortality and prolonged mechanical ventilation . A substantial fraction of patients ( 28 % ) did not require mechanical ventilation at the onset of ALI ; 46 % of these patients eventually required intubation for worsening ALI . CONCLUSIONS Mortality in pediatric ALI/ARDS is high and several risk factors have major prognostic value . In contrast to ALI/ARDS in adults , the initial severity of arterial hypoxemia in children correlates well with mortality . A significant fraction of patients with pediatric ALI/ARDS can be identified before endotracheal intubation is required . These patients provide a valuable group in whom new therapies can be tested OBJECTIVE : This population -based , prospect i ve , cohort study was design ed to determine the population incidence and outcomes of pediatric acute lung injury . METHODS : Between 1999 and 2000 , 1 year of screening was performed at all hospitals admitting critically ill children in King County , Washington . County residents 0.5 to 15 years of age who required invasive ( through endotracheal tube or tracheostomy ) or noninvasive ( through full face mask ) mechanical ventilation , regardless of the duration of mechanical ventilation , were screened . From this population , children meeting North American-European Consensus Conference acute lung injury criteria were eligible for enrollment . Postoperative patients who received mechanical ventilation for < 24 hours were excluded . Data collected included the presence of predefined cardiac conditions , demographic and physiological data , duration of mechanical ventilation , and deaths . US Census population figures were used to estimate incidence . Associations between outcomes and subgroups identified a priori were assessed . RESULTS : Thirty-nine children met the criteria for acute lung injury , result ing in a calculated incidence of 12.8 cases per 100000 person-years . Severe sepsis ( with pneumonia as the infection focus ) was the most common risk factor . The median 24-hour Pediatric Risk of Mortality III score was 9.0 , and the mean ± SD was 11.7 ± 7.5 . The hospital mortality rate was 18 % , lower than that reported previously for pediatric acute lung injury . There were no statistically significant associations between age , gender , or risk factors and outcomes . CONCLUSIONS : We present the first population -based estimate of pediatric acute lung injury incidence in the United States . Population incidence and mortality rates are lower than those for adult acute lung injury . Low mortality rates in pediatric acute lung injury may necessitate clinical trial outcome measures other than death 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 Objective To describe the daily practice of mechanical ventilation ( MV ) , and secondarily , its outcome in pediatric intensive care units ( PICUs ) . Design Prospect i ve cohort of infants and children who received MV for at least 12 h. Setting Thirty-six medical surgical PICUs . Patients All consecutive patients admitted to the PICUs during 2-month period . Measurements and main results Of the 1893 patients admitted , 659 ( 35 % ) received MV for a median time of 4 days ( 25th percentile , 75 % : 2 , 6 ) . Median of age was 13 months ( 25th percentile , 75 % : 5 , 48 ) . Common indications for MV were acute respiratory failure ( ARF ) in 72 % of the patients , altered mental status in 14 % of the patients , and ARF on chronic pulmonary disease in 10 % of the patients . Median length of stay in the PICUs was 8 days ( 25th percentile , 75 % : 5 , 13 ) . Overall mortality rate in the PICUs was 15 % ( confidence interval 95 % : 13–18 ) for the entire population , 50 % ( 95 % CI : 25–74 ) in patients who received MV because of acute respiratory distress syndrome , 24 % ( 95 % CI : 16–35 ) in patients who received MV for altered mental status and 16 % ( 95 % CI : 9–29 ) in patients who received MV for ARF on chronic pulmonary disease . Conclusion One in every 3 patients admitted to the PICUs requires ventilatory support .. The ARF was the most common reason for MV , and survival of unselected infants and children receiving MV for more than 12 h was 85 % OBJECTIVE : to investigate the relationship between mechanical ventilation and mortality and the practice of mechanical ventilation applied in children admitted to a high-complexity pediatric intensive care unit in the city of São Paulo , Brazil . DESIGN : Prospect i ve cohort study of all consecutive patients admitted to a Brazilian high-complexity PICU who were placed on mechanical ventilation for 24 hours or more , between October 1st , 2005 and March 31st , 2006 . RESULTS : Of the 241 patients admitted , 86 ( 35.7 % ) received mechanical ventilation for 24  hours  or more . Of these , 49 met inclusion criteria and were thus eligible to participate in the study . Of the 49 patients studied , 45 had chronic functional status . The median age of participants was 32 months and the median length of mechanical ventilation use was 6.5 days . The major indication for mechanical ventilation was acute respiratory failure , usually associated with severe sepsis / septic shock . Pressure ventilation modes were the st and ard ones . An overall 10.37 % incidence of Acute Respiratory Distress Syndrome was found , in addition to tidal volumes > 8 ml/kg , as well as normo- or hypocapnia . A total of 17 children died . Risk factors for mortality within 28 days of admission were initial inspiratory pressure , pH , PaO2/FiO2 ratio , oxygenation index and also oxygenation index at 48 hours of mechanical ventilation . Initial inspiratory pressure was also a predictor of mechanical ventilation for periods longer than 7 days . CONCLUSION : Of the admitted children , 35.7 % received mechanical ventilation for 24 h or more . Pressure ventilation modes were st and ard . Of the children studied , 91 % had chronic functional status . There was a high incidence of Acute Respiratory Distress Syndrome , but a lung-protective strategy was not fully implemented . Inspiratory pressure at the beginning of mechanical ventilation was a predictor of mortality within 28 days and of a longer course of mechanical ventilation RATIONALE Ventilator-induced lung injury has been predominantly studied in adults . OBJECTIVES To explore the effects of age and lung development on susceptibility to such injury . METHODS Ex vivo isolated nonperfused rat lungs ( infant , juvenile , and adult ) were mechanically ventilated where VT was based on milliliters per kilogram of body weight or as a percentage of the measured total lung capacity ( TLC ) . In vivo anesthetized rats ( infant , adult ) were mechanically ventilated with pressure-limited VTs . Allocation to ventilation strategy was r and omized . MEASUREMENTS Ex vivo injury was assessed by pressure-volume analysis , reduction in TLC , and histology , and in vivo injury by lung compliance , cytokine production , and wet- to dry-weight ratio . MAIN RESULTS Ex vivo ventilation ( VT 30 ml.kg(-1 ) ) result ed in a significant reduction ( 36.0 + /- 10.1 % , p < 0.05 ) in TLC in adult but not in infant lungs . Ex vivo ventilation ( VT 50 % TLC ) result ed in a significant reduction in TLC in both adult ( 27.8 + /- 2.8 % ) and infant ( 10.6 + /- 7.0 % ) lungs , but more so in the adult lungs ( p < 0.05 ) ; these changes were paralleled by histology and pressure-volume characteristics . After high stretch in vivo ventilation , adult but not infant rats developed lung injury ( total lung compliance , wet/dry ratio , tumor necrosis factor alpha ) . Surface video microscopy demonstrated greater heterogeneity of alveolar distension in ex vivo adult versus infant lungs . CONCLUSION These data provide ex vivo and in vivo evidence that comparable ventilator setting s are significantly more injurious in the adult than infant rat lung , probably reflecting differences in intrinsic susceptibility or inflation pattern Because animal studies have demonstrated that mechanical ventilation at high volume and pressure can be deleterious to the lungs , limitation of airway pressure , allowing hypercapnia if necessary , is already used for ventilation of acute respiratory distress syndrome ( ARDS ) . Whether a systematic and more drastic reduction is necessary is debatable . A multicenter r and omized study was undertaken to compare a strategy aim ed at limiting the end-inspiratory plateau pressure to 25 cm H2O , using tidal volume ( VT ) below 10 ml/kg of body weight , versus a more conventional ventilatory approach ( with regard to current practice ) using VT at 10 ml/kg or above and close to normal PaCO2 . Both arms used a similar level of positive end-expiratory pressure . A total of 116 patients with ARDS and no organ failure other than the lung were enrolled over 32 mo in 25 centers . The two groups were similar at inclusion . Patients in the two arms were ventilated with different VT ( 7.1 + /- 1.3 versus 10.3 + /- 1.7 ml/kg at Day 1 , p < 0.001 ) and plateau pressures ( 25.7 + /- 5 . 0 versus 31.7 + /- 6.6 cm H2O at Day 1 , p < 0.001 ) , result ing in different PaCO2 ( 59.5 + /- 15.0 versus 41.3 + /- 7.6 mm Hg , p < 0.001 ) and pH ( 7.28 + /- 0.09 versus 7.4 + /- 0.09 , p < 0.001 ) , but a similar level of oxygenation . The new approach did not reduce mortality at Day 60 ( 46.6 % versus 37.9 % in control subjects , p = 0.38 ) , the duration of mechanical ventilation ( 23.1 + /- 20.2 versus 21.4 + /- 16 . 3 d , p = 0.85 ) , the incidence of pneumothorax ( 14 % versus 12 % , p = 0 . 78 ) , or the secondary occurrence of multiple organ failure ( 41 % versus 41 % , p = 1 ) . We conclude that no benefit could be observed with reduced VT titrated to reach plateau pressures around 25 cm H2O compared with 
    Output:
    
agent
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: RATIONALE The 1994 American European Consensus Committee definitions of acute lung injury ( ALI ) and the acute respiratory distress syndrome ( ARDS ) have not been applied systematic ally in the pediatric population . OBJECTIVES The purpose of this study was to evaluate prospect ively the epidemiology and clinical risk factors associated with death and prolonged mechanical ventilation in all pediatric patients admitted to two large , pediatric intensive care units with ALI/ARDS using Consensus criteria . METHODS All pediatric patients meeting Consensus Committee definitions for ALI were prospect ively identified and included in a relational data base . MEASUREMENTS AND MAIN RESULTS There were 328 admissions for ALI/ARDS with a mortality of 22 % . Multivariate logistic regression analyses revealed ( 1 ) the initial severity of oxygenation defect , as measured by the Pa(O2)/FI(O2 ) ratio ; ( 2 ) the presence of nonpulmonary and non- central nervous system ( CNS ) organ dysfunction ; and ( 3 ) the presence of CNS dysfunction were independently associated with mortality and prolonged mechanical ventilation . A substantial fraction of patients ( 28 % ) did not require mechanical ventilation at the onset of ALI ; 46 % of these patients eventually required intubation for worsening ALI . CONCLUSIONS Mortality in pediatric ALI/ARDS is high and several risk factors have major prognostic value . In contrast to ALI/ARDS in adults , the initial severity of arterial hypoxemia in children correlates well with mortality . A significant fraction of patients with pediatric ALI/ARDS can be identified before endotracheal intubation is required . These patients provide a valuable group in whom new therapies can be tested OBJECTIVE : This population -based , prospect i ve , cohort study was design ed to determine the population incidence and outcomes of pediatric acute lung injury . METHODS : Between 1999 and 2000 , 1 year of screening was performed at all hospitals admitting critically ill children in King County , Washington . County residents 0.5 to 15 years of age who required invasive ( through endotracheal tube or tracheostomy ) or noninvasive ( through full face mask ) mechanical ventilation , regardless of the duration of mechanical ventilation , were screened . From this population , children meeting North American-European Consensus Conference acute lung injury criteria were eligible for enrollment . Postoperative patients who received mechanical ventilation for < 24 hours were excluded . Data collected included the presence of predefined cardiac conditions , demographic and physiological data , duration of mechanical ventilation , and deaths . US Census population figures were used to estimate incidence . Associations between outcomes and subgroups identified a priori were assessed . RESULTS : Thirty-nine children met the criteria for acute lung injury , result ing in a calculated incidence of 12.8 cases per 100000 person-years . Severe sepsis ( with pneumonia as the infection focus ) was the most common risk factor . The median 24-hour Pediatric Risk of Mortality III score was 9.0 , and the mean ± SD was 11.7 ± 7.5 . The hospital mortality rate was 18 % , lower than that reported previously for pediatric acute lung injury . There were no statistically significant associations between age , gender , or risk factors and outcomes . CONCLUSIONS : We present the first population -based estimate of pediatric acute lung injury incidence in the United States . Population incidence and mortality rates are lower than those for adult acute lung injury . Low mortality rates in pediatric acute lung injury may necessitate clinical trial outcome measures other than death 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 Objective To describe the daily practice of mechanical ventilation ( MV ) , and secondarily , its outcome in pediatric intensive care units ( PICUs ) . Design Prospect i ve cohort of infants and children who received MV for at least 12 h. Setting Thirty-six medical surgical PICUs . Patients All consecutive patients admitted to the PICUs during 2-month period . Measurements and main results Of the 1893 patients admitted , 659 ( 35 % ) received MV for a median time of 4 days ( 25th percentile , 75 % : 2 , 6 ) . Median of age was 13 months ( 25th percentile , 75 % : 5 , 48 ) . Common indications for MV were acute respiratory failure ( ARF ) in 72 % of the patients , altered mental status in 14 % of the patients , and ARF on chronic pulmonary disease in 10 % of the patients . Median length of stay in the PICUs was 8 days ( 25th percentile , 75 % : 5 , 13 ) . Overall mortality rate in the PICUs was 15 % ( confidence interval 95 % : 13–18 ) for the entire population , 50 % ( 95 % CI : 25–74 ) in patients who received MV because of acute respiratory distress syndrome , 24 % ( 95 % CI : 16–35 ) in patients who received MV for altered mental status and 16 % ( 95 % CI : 9–29 ) in patients who received MV for ARF on chronic pulmonary disease . Conclusion One in every 3 patients admitted to the PICUs requires ventilatory support .. The ARF was the most common reason for MV , and survival of unselected infants and children receiving MV for more than 12 h was 85 % OBJECTIVE : to investigate the relationship between mechanical ventilation and mortality and the practice of mechanical ventilation applied in children admitted to a high-complexity pediatric intensive care unit in the city of São Paulo , Brazil . DESIGN : Prospect i ve cohort study of all consecutive patients admitted to a Brazilian high-complexity PICU who were placed on mechanical ventilation for 24 hours or more , between October 1st , 2005 and March 31st , 2006 . RESULTS : Of the 241 patients admitted , 86 ( 35.7 % ) received mechanical ventilation for 24  hours  or more . Of these , 49 met inclusion criteria and were thus eligible to participate in the study . Of the 49 patients studied , 45 had chronic functional status . The median age of participants was 32 months and the median length of mechanical ventilation use was 6.5 days . The major indication for mechanical ventilation was acute respiratory failure , usually associated with severe sepsis / septic shock . Pressure ventilation modes were the st and ard ones . An overall 10.37 % incidence of Acute Respiratory Distress Syndrome was found , in addition to tidal volumes > 8 ml/kg , as well as normo- or hypocapnia . A total of 17 children died . Risk factors for mortality within 28 days of admission were initial inspiratory pressure , pH , PaO2/FiO2 ratio , oxygenation index and also oxygenation index at 48 hours of mechanical ventilation . Initial inspiratory pressure was also a predictor of mechanical ventilation for periods longer than 7 days . CONCLUSION : Of the admitted children , 35.7 % received mechanical ventilation for 24 h or more . Pressure ventilation modes were st and ard . Of the children studied , 91 % had chronic functional status . There was a high incidence of Acute Respiratory Distress Syndrome , but a lung-protective strategy was not fully implemented . Inspiratory pressure at the beginning of mechanical ventilation was a predictor of mortality within 28 days and of a longer course of mechanical ventilation RATIONALE Ventilator-induced lung injury has been predominantly studied in adults . OBJECTIVES To explore the effects of age and lung development on susceptibility to such injury . METHODS Ex vivo isolated nonperfused rat lungs ( infant , juvenile , and adult ) were mechanically ventilated where VT was based on milliliters per kilogram of body weight or as a percentage of the measured total lung capacity ( TLC ) . In vivo anesthetized rats ( infant , adult ) were mechanically ventilated with pressure-limited VTs . Allocation to ventilation strategy was r and omized . MEASUREMENTS Ex vivo injury was assessed by pressure-volume analysis , reduction in TLC , and histology , and in vivo injury by lung compliance , cytokine production , and wet- to dry-weight ratio . MAIN RESULTS Ex vivo ventilation ( VT 30 ml.kg(-1 ) ) result ed in a significant reduction ( 36.0 + /- 10.1 % , p < 0.05 ) in TLC in adult but not in infant lungs . Ex vivo ventilation ( VT 50 % TLC ) result ed in a significant reduction in TLC in both adult ( 27.8 + /- 2.8 % ) and infant ( 10.6 + /- 7.0 % ) lungs , but more so in the adult lungs ( p < 0.05 ) ; these changes were paralleled by histology and pressure-volume characteristics . After high stretch in vivo ventilation , adult but not infant rats developed lung injury ( total lung compliance , wet/dry ratio , tumor necrosis factor alpha ) . Surface video microscopy demonstrated greater heterogeneity of alveolar distension in ex vivo adult versus infant lungs . CONCLUSION These data provide ex vivo and in vivo evidence that comparable ventilator setting s are significantly more injurious in the adult than infant rat lung , probably reflecting differences in intrinsic susceptibility or inflation pattern Because animal studies have demonstrated that mechanical ventilation at high volume and pressure can be deleterious to the lungs , limitation of airway pressure , allowing hypercapnia if necessary , is already used for ventilation of acute respiratory distress syndrome ( ARDS ) . Whether a systematic and more drastic reduction is necessary is debatable . A multicenter r and omized study was undertaken to compare a strategy aim ed at limiting the end-inspiratory plateau pressure to 25 cm H2O , using tidal volume ( VT ) below 10 ml/kg of body weight , versus a more conventional ventilatory approach ( with regard to current practice ) using VT at 10 ml/kg or above and close to normal PaCO2 . Both arms used a similar level of positive end-expiratory pressure . A total of 116 patients with ARDS and no organ failure other than the lung were enrolled over 32 mo in 25 centers . The two groups were similar at inclusion . Patients in the two arms were ventilated with different VT ( 7.1 + /- 1.3 versus 10.3 + /- 1.7 ml/kg at Day 1 , p < 0.001 ) and plateau pressures ( 25.7 + /- 5 . 0 versus 31.7 + /- 6.6 cm H2O at Day 1 , p < 0.001 ) , result ing in different PaCO2 ( 59.5 + /- 15.0 versus 41.3 + /- 7.6 mm Hg , p < 0.001 ) and pH ( 7.28 + /- 0.09 versus 7.4 + /- 0.09 , p < 0.001 ) , but a similar level of oxygenation . The new approach did not reduce mortality at Day 60 ( 46.6 % versus 37.9 % in control subjects , p = 0.38 ) , the duration of mechanical ventilation ( 23.1 + /- 20.2 versus 21.4 + /- 16 . 3 d , p = 0.85 ) , the incidence of pneumothorax ( 14 % versus 12 % , p = 0 . 78 ) , or the secondary occurrence of multiple organ failure ( 41 % versus 41 % , p = 1 ) . We conclude that no benefit could be observed with reduced VT titrated to reach plateau pressures around 25 cm H2O compared with 
    Output:
    