***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 
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    Input: CONTEXT The need for lung protection is universally accepted , but the optimal level of positive end-expiratory pressure ( PEEP ) in patients with acute lung injury ( ALI ) or acute respiratory distress syndrome remains debated . OBJECTIVE To compare the effect on outcome of a strategy for setting PEEP aim ed at increasing alveolar recruitment while limiting hyperinflation to one aim ed at minimizing alveolar distension in patients with ALI . DESIGN , SETTING , AND PATIENTS A multicenter r and omized controlled trial of 767 adults ( mean [ SD ] age , 59.9 [ 15.4 ] years ) with ALI conducted in 37 intensive care units in France from September 2002 to December 2005 . INTERVENTION Tidal volume was set at 6 mL/kg of predicted body weight in both strategies . Patients were r and omly assigned to a moderate PEEP strategy ( 5 - 9 cm H(2)O ) ( minimal distension strategy ; n = 382 ) or to a level of PEEP set to reach a plateau pressure of 28 to 30 cm H(2)O ( increased recruitment strategy ; n = 385 ) . MAIN OUTCOME MEASURES The primary end point was mortality at 28 days . Secondary end points were hospital mortality at 60 days , ventilator-free days , and organ failure-free days at 28 days . RESULTS The 28-day mortality rate in the minimal distension group was 31.2 % ( n = 119 ) vs 27.8 % ( n = 107 ) in the increased recruitment group ( relative risk , 1.12 [ 95 % confidence interval , 0.90 - 1.40 ] ; P = .31 ) . The hospital mortality rate in the minimal distension group was 39.0 % ( n = 149 ) vs 35.4 % ( n = 136 ) in the increased recruitment group ( relative risk , 1.10 [ 95 % confidence interval , 0.92 - 1.32 ] ; P = .30 ) . The increased recruitment group compared with the minimal distension group had a higher median number of ventilator-free days ( 7 [ interquartile range { IQR } , 0 - 19 ] vs 3 [ IQR , 0 - 17 ] ; P = .04 ) and organ failure-free days ( 6 [ IQR , 0 - 18 ] vs 2 [ IQR , 0 - 16 ] ; P = .04 ) . This strategy also was associated with higher compliance values , better oxygenation , less use of adjunctive therapies , and larger fluid requirements . CONCLUSIONS A strategy for setting PEEP aim ed at increasing alveolar recruitment while limiting hyperinflation did not significantly reduce mortality . However , it did improve lung function and reduced the duration of mechanical ventilation and the duration of organ failure . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00188058 Twenty neonates requiring mechanical ventilation for respiratory failure , including 13 with hyaline membrane disease , were studied to assess the effects of alterations in ventilator setting s on mean airway pressure ( MAP ) , blood gases , and intracranial pressure ( ICP ) . The study involved r and om alterations in peak inspiratory pressure ( PIP ) , positive end-expiratory pressure ( PEEP ) , and inspiratory/expiratory ratio while MAP , PaO2 , ICP , and end-tibal PCO2 were continuously monitored . The results showed a significant relationship between MAP and PaO2 that was expressed as the change in PaO2 per millimeter of mercury change in MAP ( delta PaO2/delta MAP ) with a mean delta PaO2/delta MAP of 4.92 . The delta PaO2/delta MAP was highest for changes in PEEP ( 6.08 ) , followed by PIP ( 5.07 ) , and inspiratory/expiratory ratio ( 1.9 ) . There was a significant relationship between alterations in PEEP and PIP vs PaCO2 and pH. Increases in PEEP and decreases in PIP result ed in an elevated PaCO2 and a lowered pH , and decreases in PEEP and increases in PIP result ed in a decreased PaCO2 and an elevated pH. There was no significant relationship between MAP and ICP , but there was a significant association between delta ICP and delta PaCO2 during alterations in PIP ( r = .64 , P less than .001 ) . Increases in PEEP will lead to the greatest increase in PaO2 per change in MAP , followed by increase in PIP and inspiratory/expiratory ratio using a pressure-limited ventilator Abstract Positive end expiratory pressure is routinely used when ventilating preterm infants . Elevation of PEEP increases lung volume , as does surfactant treatment . The purpose of this study was to investigate the effect of various levels of PEEP within the range of 0.2 to 0.4 kPa on lung volume , compliance and gas exchange . We measured functional residual capacity , compliance of the respiratory system and arterial blood gases in 20 infants ( median birth weight 1240 g , range 660–1690 g ; median gestational age 28 weeks , range 24–32 weeks ; postnatal age 3–4 days ) . The infants were studied at 72 hours after their last dose of natural surfactant . At this time the patients were routinely nursed at 0.3 kPa of PEEP , the PEEP level was lowered to 0.2 kPa or raised to 0.4 kPa in r and om order . The PEEP level was then changed to the third level 0.4 kPa or 0.2 kPa . Each new setting was maintained for 20 min before FRC , compliance and blood gases were measured . FRC was assessed using SF6 washout technique . Increasing PEEP from 0.2 to 0.3 to 0.4 kPa result ed in increases in FRC ( p < 0.01 ) and oxygenation ( ns ) in all infants . In 16 infants compliance decreased and paCO2 increased with elevation of PEEP . Only in 4 infants compliance increased and CO2 fell . Conclusion : In the majority of our infants reduction of PEEP from 0.4 to 0.2 kPa result ed in increases in compliance and CO2 reduction . Our results might suggest that relatively low levels of PEEP < 0.3 kPa may be appropriate at 72 hours after surfactant replacement . Furthermore , these results underline the importance of PEEP test in clinical practice Sixteen rabbits were anaesthetized and subjected to saline lavage of the lungs to produce surfactant deficiency . This result ed in an arterial oxygen tension of less than 12 kPa on 100 % inspired oxygen and an inflection point on the pressure-volume curve at a pressure of 8–12 mmHg . After lavage the animals were r and omly assigned to receive either conventional mechanical ventilation ( CMV ) with a positive end-expiratory pressure ( PEEP ) of 1–2 mmHg ( group I —low PEEP ) or CMV with PEEP equal to the inflection point pressure ( group II — high PEEP ) . Mean airway pressures were kept at 14–16 mmHg in both groups by increasing the inspiratory : expiratory time ratios in the low PEEP group . The 5-h protocol was completed by 4 animals in group I and 6 animals in group II , early death usually being associated with a metabolic acidosis . On 100 % oxygen , the mean PaO2 at 2-h post-lavage was 15.2±8.3 kPa in group I and 39.6±21.8 kPa in group II . Group I had much lower end-expiratory lung volumes ( 3.0±1.5 ml above FRC ) than group II ( 34.9±12.2 ml above FRC ) . Histological examination of the lungs revealed significantly less hyaline membrane formation in group II ( p=0.001 ) . Thus , the prevention of alveolar collapse by the use of high PEEP levels appears to reduce lung damage in this preparation BACKGROUND There are limited data to inform the choice between early treatment with continuous positive airway pressure ( CPAP ) and early surfactant treatment as the initial support for extremely-low-birth-weight infants . METHODS We performed a r and omized , multicenter trial , with a 2-by-2 factorial design , involving infants who were born between 24 weeks 0 days and 27 weeks 6 days of gestation . Infants were r and omly assigned to intubation and surfactant treatment ( within 1 hour after birth ) or to CPAP treatment initiated in the delivery room , with subsequent use of a protocol -driven limited ventilation strategy . Infants were also r and omly assigned to one of two target ranges of oxygen saturation . The primary outcome was death or bronchopulmonary dysplasia as defined by the requirement for supplemental oxygen at 36 weeks ( with an attempt at withdrawal of supplemental oxygen in neonates who were receiving less than 30 % oxygen ) . RESULTS A total of 1316 infants were enrolled in the study . The rates of the primary outcome did not differ significantly between the CPAP group and the surfactant group ( 47.8 % and 51.0 % , respectively ; relative risk with CPAP , 0.95 ; 95 % confidence interval [ CI ] , 0.85 to 1.05 ) after adjustment for gestational age , center , and familial clustering . The results were similar when bronchopulmonary dysplasia was defined according to the need for any supplemental oxygen at 36 weeks ( rates of primary outcome , 48.7 % and 54.1 % , respectively ; relative risk with CPAP , 0.91 ; 95 % CI , 0.83 to 1.01 ) . Infants who received CPAP treatment , as compared with infants who received surfactant treatment , less frequently required intubation or postnatal corticosteroids for bronchopulmonary dysplasia ( P<0.001 ) , required fewer days of mechanical ventilation ( P=0.03 ) , and were more likely to be alive and free from the need for mechanical ventilation by day 7 ( P=0.01 ) . The rates of other adverse neonatal outcomes did not differ significantly between the two groups . CONCLUSIONS The results of this study support consideration of CPAP as an alternative to intubation and surfactant in preterm infants . ( Clinical Trials.gov number , NCT00233324 . A controlled trial of elective intervention with continuous inflating pressure ( CIP ) was performed in infants with severe hyaline membrane disease who weighed more than 1000 g at birth . Infants entered the trial if their arterial oxygen tension ( PaO2 ) fell below 60 mmHg while breathing a fractional inspired oxygen concentration ( F1O2 ) greater than 0 - 95 . 11 out of 12 infants in the CIP-treated group and 10 out of 12 in the control group survived . 7 treated and 6 control infants required  mechanical ventilation .  When CIP was started the Pao2 of the treated infants increased , and they breathed high concentrations of oxygen for a significantly shorter period than the control infants . During the 31-month duration of the trial 107 other infants with severe hyaline membrane disease were admitted who did not meet the criteria for entry to the trial . 37 survived after breathing high concentrations of oxygen ( F1O2 greater than 0 - 60 ) spontaneously without any ventilatory assistance , and the remaining 70 infants were already being ventilated on their arrival in the unit , usually because they had required mechanical ventilation during transfer from other hospitals . The neonatal survival rate for those infants born in this hospital during the study period was 88 % ( 50 out of 57 infants ) and for those referred from other hospitals it was 69 % ( 51 out of 74 infants ) . The maximum further increase in overall survival rate that might have been achieved in our population of infants if CIP had been initiated very early in the course of the illness was 5%--i.e . from 77 % ( 101/131 ) to 82 % ( 107/131 ) Objectives : To compare the effects of low vs. high tidal volume ( Vt ) with three positive end-expiratory pressure ( PEEP ) strategies on activated neutrophil influx into the lung . Design : Prospect i ve , r and omized controlled animal study . Setting : Animal laboratory in a university hospital . Subjects : Newborn piglets . Interventions : Surfactant-depleted piglets were r and omized in littermate pairs ; to PEEP of either 0 ( zero end-expiratory pressure [ ZEEP ] ; n = 6 ) , 8 cm H2O ( PEEP 8 ; n = 5 ) , or 1 cm H2O above the lower inflection point ( LIP ) ( PEEP > LIP ; n = 6 ) . Within each pair piglets were r and omized to a low Vt ( 5–7 mL/kg ) or high Vt strategy ( 17–19 mL/kg ) . After 4 hrs of mechanical ventilation , 18-fluorodeoxyglucose ( 18FDG ) was injected and positron emission tomography scanning was performed . Measurements and Main Results : Vt and PEEP changes on influx constants of 18FDG were assessed by analysis of variance . A within-litter comparison of Vt was nonsignificant ( p = .50 ) . A between-litter comparison , ordered in linear trend rank , from ZEEP , to PEEP 8 , to PEEP > LIP , showed a strong effect of PEEP on influx constant ( p = .019 ) . Conclusions : PEEP set above the LIP on the inspiratory limb of 
    Output:
    
There is insufficient evidence to guide selection of appropriate PEEP levels for RDS or CMV .