Open Lung Approach for the Acute Respiratory Distress Syndrome: A Pilot, Randomized Controlled Trial* Effect of Lung Recruitment and Titrated Positive End-Expiratory Pressure (PEEP) vs Low PEEP on Mortality in Patients With Acute Respiratory Distress Syndrome: A Randomized Clinical Trial Regional distribution of gas and tissue in acute respiratory distress syndrome. III. Consequences for the effects of positive end-expiratory pressure Acute Respiratory Distress Syndrome: Pathophysiology and Therapeutic Options A randomised controlled trial of an open lung strategy with staircase recruitment, titrated PEEP and targeted low airway pressures in patients with acute respiratory distress syndrome Respiratory and haemodynamic changes during decremental open lung positive end-expiratory pressure titration in patients with acute respiratory distress syndrome Ventilation strategy using low tidal volumes, recruitment maneuvers, and high positive end-expiratory pressure for acute lung injury and acute respiratory distress syndrome: a randomized controlled trial. [A study on the effect of recruitment maneuver imposed on extravascular lung water in patients with acute respiratory distress syndrome]. Reversibility of lung collapse and hypoxemia in early acute respiratory distress syndrome. Clinical efficacy and safety of recruitment maneuver in patients with acute respiratory distress syndrome using low tidal volume ventilation: a multicenter randomized controlled clinical trial. Recruitment Maneuvers after a Positive End-expiratory Pressure Trial Do Not Induce Sustained Effects in Early Adult Respiratory Distress Syndrome Effect of a protective-ventilation strategy on mortality in the acute respiratory distress syndrome. Hemodynamic and respiratory changes during lung recruitment and descending optimal positive end-expiratory pressure titration in patients with acute respiratory distress syndrome. [Effects of high positive end-expiratory pressure combined with recruitment maneuvers in patients with acute respiratory distress syndrome]. Epidemiology, Patterns of Care, and Mortality for Patients With Acute Respiratory Distress Syndrome in Intensive Care Units in 50 Countries.
Objective : The open lung approach is a mechanical ventilation strategy involving lung recruitment and a decremental positive end-expiratory pressure trial . We compared the Acute Respiratory Distress Syndrome network protocol using low levels of positive end-expiratory pressure with open lung approach result ing in moderate to high levels of positive end-expiratory pressure for the management of established moderate/severe acute respiratory distress syndrome . Design : A prospect i ve , multicenter , pilot , r and omized controlled trial . Setting : A network of 20 multidisciplinary ICUs . Patients : Patients meeting the American-European Consensus Conference definition for acute respiratory distress syndrome were considered for the study . Interventions : At 12 - 36 hours after acute respiratory distress syndrome onset , patients were  assessed under st and ardized ventilator setting s ( FIO2≥0.5 , positive end-expiratory pressure ≥10 cm H2O ) . If Pao2/FIO2 ratio remained less than or equal to 200 mm Hg , patients were r and omized to open lung approach or Acute Respiratory Distress Syndrome network protocol . All patients were ventilated with a tidal volume of 4 to 8 ml/kg predicted body weight . Measurements and Main Results : From 1,874 screened patients with acute respiratory distress syndrome , 200 were r and omized : 99 to open lung approach and 101 to Acute Respiratory Distress Syndrome network protocol . Main outcome measures were 60-day and ICU mortalities , and ventilator-free days . Mortality at day-60 ( 29 % open lung approach vs. 33 % Acute Respiratory Distress Syndrome Network protocol , p = 0.18 , log rank test ) , ICU mortality ( 25 % open lung approach vs. 30 % Acute Respiratory Distress Syndrome network protocol , p = 0.53 Fisher ’s exact test ) , and ventilator-free days ( 8 [ 0 - 20 ] open lung approach vs. 7 [ 0 - 20 ] d Acute Respiratory Distress Syndrome network protocol , p = 0.53 Wilcoxon rank test ) were not significantly different . Airway driving pressure ( plateau pressure - positive end-expiratory pressure ) and PaO2/FIO2 improved significantly at 24 , 48 and 72 hours in patients in open lung approach compared with patients in Acute Respiratory Distress Syndrome network protocol . Barotrauma rate was similar in both groups . Conclusions : In patients with established acute respiratory distress syndrome , open lung approach improved oxygenation and driving pressure , without detrimental effects on mortality , ventilator-free days , or barotrauma . This pilot study supports the need for a large , multicenter trial using recruitment maneuvers and a decremental positive end-expiratory pressure trial in persistent acute respiratory distress syndrome Importance The effects of recruitment maneuvers and positive end-expiratory pressure ( PEEP ) titration on clinical outcomes in patients with acute respiratory distress syndrome ( ARDS ) remain uncertain . Objective To determine if lung recruitment associated with PEEP titration according to the best respiratory-system compliance decreases 28-day mortality of patients with moderate to severe ARDS compared with a conventional low-PEEP strategy . Design , Setting , and Participants Multicenter , r and omized trial conducted at 120 intensive care units ( ICUs ) from 9 countries from November 17 , 2011 , through April 25 , 2017 , enrolling adults with moderate to severe ARDS . Interventions An experimental strategy with a lung recruitment maneuver and PEEP titration according to the best respiratory – system compliance ( n = 501 ; experimental group ) or a control strategy of low PEEP ( n = 509 ) . All patients received volume-assist control mode until weaning . Main Outcomes and Measures The primary outcome was all-cause mortality until 28 days . Secondary outcomes were length of ICU and hospital stay ; ventilator-free days through day 28 ; pneumothorax requiring drainage within 7 days ; barotrauma within 7 days ; and ICU , in-hospital , and 6-month mortality . Results A total of 1010 patients ( 37.5 % female ; mean [ SD ] age , 50.9 [ 17.4 ] years ) were enrolled and followed up . At 28 days , 277 of 501 patients ( 55.3 % ) in the experimental group and 251 of 509 patients ( 49.3 % ) in the control group had died ( hazard ratio [ HR ] , 1.20 ; 95 % CI , 1.01 to 1.42 ; P = .041 ) . Compared with the control group , the experimental group strategy increased 6-month mortality ( 65.3 % vs 59.9 % ; HR , 1.18 ; 95 % CI , 1.01 to 1.38 ; P = .04 ) , decreased the number of mean ventilator-free days ( 5.3 vs 6.4 ; difference , −1.1 ; 95 % CI , −2.1 to −0.1 ; P = .03 ) , increased the risk of pneumothorax requiring drainage ( 3.2 % vs 1.2 % ; difference , 2.0 % ; 95 % CI , 0.0 % to 4.0 % ; P = .03 ) , and the risk of barotrauma ( 5.6 % vs 1.6 % ; difference , 4.0 % ; 95 % CI , 1.5 % to 6.5 % ; P = .001 ) . There were no significant differences in the length of ICU stay , length of hospital stay , ICU mortality , and in-hospital mortality . Conclusions and Relevance In patients with moderate to severe ARDS , a strategy with lung recruitment and titrated PEEP compared with low PEEP increased 28-day all-cause mortality . These findings do not support the routine use of lung recruitment maneuver and PEEP titration in these patients . Trial Registration clinical trials.gov Identifier : Objective : To determine whether differences in lung morphology assessed by computed tomography ( CT ) affect the response to positive end-expiratory pressure (PEEP).¶ Design : Prospect i ve study over a 53-month period.¶ Setting : Fourteen-bed surgical intensive care unit of a university hospital.¶ Patients and participants : Seventy-one consecutive patients with early adult respiratory distress syndrome (ARDS).¶ Measurements and results : Fast spiral thoracic CT was performed at zero end-expiratory pressure ( ZEEP ) and after implementation of PEEP 10 cmH2O . Hemodynamic and respiratory parameters were measured in both conditions . PEEP-induced overdistension and alveolar recruitment were quantified by specifically design ed software ( Lungview ) . Overdistension occurred only in the upper lobes and was significantly correlated with the volume of lung , characterized by a CT attenuation ranging between –900 and –800 HU in ZEEP conditions . Cardiorespiratory effects of PEEP were similar in patients with primary and secondary ARDS . PEEP-induced alveolar recruitment of the lower lobes was significantly correlated with their lung volume ( gas + tissue ) at functional residual capacity . PEEP-induced alveolar recruitment was greater in the lower lobes with “ inflammatory atelectasis ” than in the lower lobes with “ mechanical atelectasis . ” Lung morphology as assessed by CT markedly influenced the effects of PEEP : in patients with diffuse CT attenuations PEEP induced a marked alveolar recruitment without overdistension , whereas in patients with lobar CT attenuations PEEP induced a mild alveolar recruitment associated with overdistension of previously aerated lung areas . These results can be explained by the uneven distribution of regional compliance characterizing patients with lobar CT attenuations ( compliant upper lobes and stiff lower lobes ) contrasting with a more even distribution of regional compliances observed in patients with diffuse CT attenuations.¶ Conclusions : In patients with ARDS , the cardiorespiratory effects of PEEP are affected by lung morphology rather than by the cause of the lung injury ( primary versus secondary ARDS ) . The regional distribution of the loss of aeration and the type of atelectasis –“mechanical ” with a massive loss of lung volume , or “ inflammatory ” with a preservation of lung volume – characterizing the lower lobes are the main determinants of the cardiorespiratory effects of PEEP Acute Respiratory Distress Syndrome ( ARDS ) is a common entity in critical care . ARDS is associated with many diagnoses , including trauma and sepsis , can lead to multiple organ failure and has high mortality . The present article is a narrative review of the literature on ARDS , including ARDS pathophysiology and therapeutic options currently being evaluated or in use in clinical practice . The literature review covers relevant publications until January 2011 . Recent developments in the therapeutic approach to ARDS include refinements of mechanical ventilatory support with emphasis on protective lung ventilation using low tidal volumes , increased PEEP with use of recruitment maneuvers to promote reopening of collapsed lung alveoli , prone position as rescue therapy for severe hypoxemia , and high frequency ventilation . Supportive measures in the management of ARDS include attention to fluid balance , restrictive transfusion strategies , and minimization of sedatives and neuromuscular blocking agents . Inhaled bronchodilators such as inhaled nitric oxide and prostagl and ins confer short term improvement without proven effect on survival , but are currently used in many centers . Use of corticosteroids is also important , and appropriate timely use may reduce mortality . Finally , extra corporeal oxygenation methods are very useful as rescue therapy in patients with intractable hypoxemia , even though a survival benefit has not , to this date been demonstrated . Despite intense ongoing research on the pathophysiology and treatment of ARDS , mortality remains high . Many pharmacologic and supportive strategies have shown promising results , but data from large r and omized clinical trials are needed to fully evaluate the true effectiveness of these therapies . Keywords ARDS ; Pathophysiology ; Introduction Tidal volume and plateau pressure minimisation are the st and ard components of a protective lung ventilation strategy for patients with acute respiratory distress syndrome ( ARDS ) . Open lung strategies , including higher positive end-expiratory pressure ( PEEP ) and recruitment manoeuvres to date have not proven efficacious . This study examines the effectiveness and safety of a novel open lung strategy , which includes permissive hypercapnia , staircase recruitment manoeuvres ( SRM ) and low airway pressure with PEEP titration . Method Twenty ARDS patients were r and omised to treatment or ARDSnet control ventilation strategies . The treatment group received SRM with decremental PEEP titration and targeted plateau pressure < 30 cm H2O . Gas exchange and lung compliance were measured daily for 7 days and plasma cytokines in the first 24 hours and on days 1 , 3 , 5 and 7 ( mean ± SE ) . Duration of ventilation , ICU stay and hospital stay ( median and interquartile range ) and hospital survival were determined . Results There were significant overall differences between groups when considering plasma IL-8 and TNF-α . For plasma IL-8 , the control group was 41 % higher than the treatment group over the seven-day period ( ratio 1.41 ( 1.11 to 1.79 ) , P = 0.01 ) , while for TNF-α the control group was 20 % higher over the seven-day period ( ratio 1.20 ( 1.01 to 1.42 ) P = 0.05 ) . PaO2/FIO2 ( 204 ± 9 versus 165 ± 9 mmHg , P = 0.005 ) and static lung compliance ( 49.1 ± 2.9 versus 33.7 ± 2.7 mls/cm H2O , P < 0.001 ) were higher in the treatment group than the control group over seven days . There was no difference in duration of ventilation ( 180 ( 87 to 298 ) versus 341 ( 131 to 351 ) hrs , P = 0.13 ) , duration of ICU stay ( 9.9 ( 5.6 to 14.8 ) versus 16.0 ( 8.1 to 19.3 ) days , P = 0.19 ) and duration of hospital stay ( 17.9 ( 13.7 to 34.5 ) versus 24.7 ( 20.5 to 39.8 ) days , P = 0.16 ) between the treatment and control groups . Conclusions This open lung strategy was associated with greater amelioration in some systemic cytokines , improved oxygenation and lung compliance over seven days . A larger trial powered to examine clinical ly-meaningful outcomes is warranted . Trial registration Introduction To investigate haemodynamic and respiratory changes during lung recruitment and decremental positive end-expiratory pressure ( PEEP ) titration for open lung ventilation in patients with acute respiratory distress syndrome ( ARDS ) a prospect i ve , clinical trial was performed involving 12 adult patients with ARDS treated in the surgical intensive care unit in a university hospital . Methods A software programme ( Open Lung Tool ™ ) incorporated into a st and ard ventilator controlled the recruitment ( pressure-controlled ventilation with fixed PEEP at 20 cmH2O and increased driving pressures at 20 , 25 and 30 cmH2O for two minutes each ) and PEEP titration ( PEEP lowered by 2 cmH2O every two minutes , with tidal volume set at 6 ml/kg ) . The open lung PEEP ( OL-PEEP ) was defined as the PEEP level yielding maximum dynamic respiratory compliance plus 2 cmH2O . Gas exchange , respiratory mechanics and central haemodynamics using the Pulse Contour Cardiac Output Monitor ( PiCCO ™ ) , as well as transoesophageal echocardiography were measured at the following steps : at baseline ( T0 ) ; during the final recruitment step with PEEP at 20 cmH2O and driving pressure at 30 cmH2O , ( T20/30 ) ; at OL-PEEP , following another recruitment manoeuvre ( TOLP ) . Results The ratio of partial pressure of arterial oxygen ( PaO2 ) to fraction of inspired oxygen ( FiO2 ) increased from T0 to TOLP ( 120 ± 59 versus 146 ± 64 mmHg , P < 0.005 ) , as did dynamic respiratory compliance ( 23 ± 5 versus 27 ± 6 ml/cmH2O , P < 0.005 ) . At constant PEEP ( 14 ± 3 cmH2O ) and tidal volumes , peak inspiratory pressure decreased ( 32 ± 3 versus 29 ± 3 cmH2O , P < 0.005 ) , although partial pressure of arterial carbon dioxide ( PaCO2 ) was unchanged ( 58 ± 22 versus 53 ± 18 mmHg ) . No significant decrease in mean arterial pressure , stroke volume or cardiac output occurred during the recruitment ( T20/30 ) . However , left ventricular end-diastolic area decreased at T20/30 due to a decrease in the left ventricular end-diastolic septal-lateral diameter , while right ventricular end-diastolic area increased . Right ventricular function , estimated by the right ventricular Tei-index , deteriorated during the recruitment manoeuvre , but improved at TOLP . Conclusions A st and ardised open lung strategy increased oxygenation and improved respiratory system compliance . No major haemodynamic compromise was observed , although the increase in right ventricular Tei-index and right ventricular end-diastolic area and the decrease in left ventricular end-diastolic septal-lateral diameter during the recruitment suggested an increased right ventricular stress and strain . Right ventricular function was significantly improved at TOLP compared with T0 , although left ventricular function was unchanged , indicating effective lung volume optimisation CONTEXT Low-tidal-volume ventilation reduces mortality in critically ill patients with acute lung injury and acute respiratory distress syndrome . Instituting additional strategies to open collapsed lung tissue may further reduce mortality . OBJECTIVE To compare an established low-tidal-volume ventilation strategy with an experimental strategy based on the original " open-lung approach , " combining low tidal volume , lung recruitment maneuvers , and high positive-end-expiratory pressure . DESIGN AND SETTING R and omized controlled trial with concealed allocation and blinded data analysis conducted between August 2000 and March 2006 in 30 intensive care units in Canada , Australia , and Saudi Arabia . PATIENTS Nine hundred eighty-three consecutive patients with acute lung injury and a ratio of arterial oxygen tension to inspired oxygen fraction not exceeding 250 . INTERVENTIONS The control strategy included target tidal volumes of 6 mL/kg of predicted body weight , plateau airway pressures not exceeding 30 cm H2O , and conventional levels of positive end-expiratory pressure ( n = 508 ) . The experimental strategy included target tidal volumes of 6 mL/kg of predicted body weight , plateau pressures not exceeding 40 cm H2O , recruitment maneuvers , and higher positive end-expiratory pressures ( n = 475 ) . MAIN OUTCOME MEASURE All-cause hospital mortality . RESULTS Eighty-five percent of the 983 study patients met criteria for acute respiratory distress syndrome at enrollment . Tidal volumes remained similar in the 2 groups , and mean positive end-expiratory pressures were 14.6 ( SD , 3.4 ) cm H2O in the experimental group vs 9.8 ( SD , 2.7 ) cm H2O among controls during the first 72 hours ( P < .001 ) . All-cause hospital mortality rates were 36.4 % and 40.4 % , respectively ( relative risk [ RR ] , 0.90 ; 95 % confidence interval [ CI ] , 0.77 - 1.05 ; P = .19 ) . Barotrauma rates were 11.2 % and 9.1 % ( RR , 1.21 ; 95 % CI , 0.83 - 1.75 ; P = .33 ) . The experimental group had lower rates of refractory hypoxemia ( 4.6 % vs 10.2 % ; RR , 0.54 ; 95 % CI , 0.34 - 0.86 ; P = .01 ) , death with refractory hypoxemia ( 4.2 % vs 8.9 % ; RR , 0.56 ; 95 % CI , 0.34 - 0.93 ; P = .03 ) , and previously defined eligible use of rescue therapies ( 5.1 % vs 9.3 % ; RR , 0.61 ; 95 % CI , 0.38 - 0.99 ; P = .045 ) . CONCLUSIONS For patients with acute lung injury and acute respiratory distress syndrome , a multifaceted protocol ized ventilation strategy design ed to recruit and open the lung result ed in no significant difference in all-cause hospital mortality or barotrauma compared with an established low-tidal-volume protocol ized ventilation strategy . This " open-lung " strategy did appear to improve secondary end points related to hypoxemia and use of rescue therapies . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00182195 OBJECTIVE To investigate the possible effects of recruitment maneuver ( RM ) imposing on extravascular lung water ( EVLW ) in patients with acute respiratory distress syndrome ( ARDS ) . METHODS Twenty patients with ARDS who were eligible for the study were r and omized to two groups , one group of which received regular therapy+RM ( RM group ) , and to the other group only regular therapy was given ( control group ) . Mechanical ventilation of all the patients was performed on the principles of lung protective ventilation . RM was carried out in bi-level positive airway passage ( BIPAP ) mode , and repeated every 8 hours per day until on the 7th day or before weaning of mechanical ventilation . The treatment was same between the two groups except RM . Baseline data and the influencing factors of EVLW were all recorded , which included everyday EVLW , extravascular lung water index ( EVLWI ) after RM , respiratory mechanics , oxygenation parameters , central venous pressure ( CVP ) , plasma colloid osmotic pressure ( COP ) , dosage of corticosteroid and adrenergic drugs , 24-hour net fluid balance . RESULTS EVLW and EVLWI in RM and control group showed a tendency of decrease with passage of time , but the difference between both groups had no statistical significance ( all P>0.05 ) . The comparisons between the influencing factors of the groups , consisting of CVP , COP , noradrenaline and hydrocortisone , had no significant difference either ( all P>0.05 ) . Dopamine dosage in RM group on the 4th day was smaller than that of control group ( P<0.05 ) . Net fluid balance in RM group on the 7th day was negative , whereas it was positive in control group ( P<0.05 ) . Mean airway pressure [ Pmean , RM group ( 18.8+/-3.2 ) cm H(2)O ( 1 cm H(2)O=0.098 kPa ) vs. control group ( 16.6+/-3.9 ) cm H(2)O ] and lung quasi-static compliance [ Cstat , RM group ( 36.5+/-14.5 ) ml/cm H(2)O vs. control group ( 29.3+/-12.0 ) ml/cm H(2)O ] in RM group were higher than those in control group ( both P<0.05 ) . Cstat on the 5th day was higher than that on the 2nd and 3rd day in RM group ( both P<0.05 ) . But oxygenation index ( PaO(2)/FiO(2 ) ) showed no distinct difference between the groups ( all P>0.05 ) . CONCLUSION RM for the patients with ARDS can merely improve lung mechanics without obvious effect on EVLW . Neither of the influencing factors involved in the study has impact on emergence and clearance of EVLW RATIONALE The hypothesis that lung collapse is detrimental during the acute respiratory distress syndrome is still debatable . One of the difficulties is the lack of an efficient maneuver to minimize it . OBJECTIVES To test if a bedside recruitment strategy , capable of reversing hypoxemia and collapse in > 95 % of lung units , is clinical ly applicable in early acute respiratory distress syndrome . METHODS Prospect i ve assessment of a stepwise maximum-recruitment strategy using multislice computed tomography and continuous blood-gas hemodynamic monitoring . MEASUREMENTS AND MAIN RESULTS Twenty-six patients received sequential increments in inspiratory airway pressures , in 5 cm H(2)O steps , until the detection of Pa(O(2 ) ) + Pa(CO(2 ) ) > or= 400 mm Hg . Whenever this primary target was not met , despite inspiratory pressures reaching 60 cm H(2)O , the maneuver was considered incomplete . If there was hemodynamic deterioration or barotrauma , the maneuver was to be interrupted . Late assessment of recruitment efficacy was performed by computed tomography ( 9 patients ) or by online continuous monitoring in the intensive care unit ( 15 patients ) up to 6 h. It was possible to open the lung and to keep the lung open in the majority ( 24/26 ) of patients , at the expense of transient hemodynamic effects and hypercapnia but without major clinical consequences . No barotrauma directly associated with the maneuver was detected . There was a strong and inverse relationship between arterial oxygenation and percentage of collapsed lung mass ( R = - 0.91 ; p < 0.0001 ) . CONCLUSIONS It is often possible to reverse hypoxemia and fully recruit the lung in early acute respiratory distress syndrome . Due to transient side effects , the required maneuver still awaits further evaluation before routine clinical application BACKGROUND The recruitment maneuver ( RM ) has been shown to improve oxygenation in some patients with acute respiratory distress syndrome . But there is a lack of st and ardization and lack of clinical studies to prove the improvement on clinical outcome . We conducted this study to evaluate the clinical efficacy and safety of the RM in patients with acute respiratory distress syndrome ( ARDS ) using low tidal volume ventilation . METHODS We r and omly assigned 110 patients with ARDS from 14 Chinese intensive care units ( ICUs ) at the tertiary teaching hospitals . Patients with PaO2 ≤ 200 mmHg at FiO2 1.0 and PEEP ≥ 10 cmH2O were included in the study . Patients were r and omized into two groups : control group and RM group . The tidal volume was set to 6 - 8 ml per kilogram of predicted body weight ( PBW ) in both groups . RM was performed by continuous positive airway pressure ( CPAP ) of 40 cmH2O maintained for 40 seconds . RMs was conducted every eight hours for the first five days , or stopped within five days if the patient reached the weaning st and ard . RESULTS One hundred and ten patients had completed the requirements for the primary study goals , 55 from the RM group and 55 control patients . Baseline characteristics remained similar in the two groups . In the RM group the PaO2/FiO2 was significantly increased compared to baseline at 120 minutes after RM on day one and day two ( P = 0.007 and P = 0.001 ) . There were no significant differences between the RM and control group in hospital mortality ( 41.8 % vs. 56.4 % , P = 0.13 ) , 28-day mortality ( 29.1 % vs. 43.6 % , P = 0.11 ) and ventilator-free days at day 28 ( 10.8 ± 10.1 vs. 7.4 ± 10.0 , P = 0.08 ) . ICU mortality ( 32.7 % vs. 52.7 % , P = 0.03 ) , the rate of survival with unassisted breathing for at least 48 consecutive hours at day 28 ( 58.2 % vs. 36.2 % , P = 0.02 ) , and nonpulmonary organ failure-free days at day 28 ( 17.4 ± 11.1 vs. 13.0 ± 12.0 , P = 0.03 ) favored the RM group . There was no significant difference in mean blood pressure and heart rate before RM and at 30 , 60 , 120 minutes after RM . There was no incidence of barotraumas . CONCLUSIONS RM was safe and useful for improving oxygenation in patients with ARDS who were ventilated with a low tidal volume , with a beneficial impact on their clinical outcome Background : Recruitment maneuvers performed in early adult respiratory distress syndrome remain a matter of dispute in patients ventilated with low tidal volumes and high levels of positive end-expiratory pressure ( PEEP ) . In this prospect i ve , r and omized controlled study the authors evaluated the impact of recruitment maneuvers after a PEEP trial on oxygenation and venous admixture ( Qs/Qt ) in patients with early extrapulmonary adult respiratory distress syndrome . Methods : After a PEEP trial 30 consecutive patients ventilated with low tidal volumes and high levels of PEEP were r and omly assigned to either undergo a recruitment maneuver or not . Data were recorded at baseline , 3 min after the recruitment maneuver , and 30 min after baseline . Recruitment maneuvers were performed with a sustained inflation of 50 cm H2O maintained for 30 s. Results : Compared with baseline the ratio of the arterial oxygen partial pressure to the fraction of inspired oxygen ( Pao2/Fio2 ) and Qs/Qt improved significantly at 3 min after the recruitment maneuver ( Pao2/Fio2 , 139 ± 46 mm Hg versus 246 ± 111 mm Hg , P < 0.001 ; Qs/Qt , 30.8 ± 5.8 % versus 21.5 ± 9.7 % , P < 0.005 ) , but baseline values were reached again within 30 min . No significant differences in Pao2/Fio2 and Qs/Qt were detected between the recruitment maneuver group and the control group at baseline and after 30 min ( recruitment maneuver group [ n = 15 ] : Pao2/Fio2 , 139 ± 46 mm Hg versus 138 ± 39 mm Hg ; Qs/Qt , 30.8 ± 5.8 % versus 29.2 ± 7.4 % ; control group : [ n = 15 ] : Pao2/Fio2 , 145 ± 33 mm Hg versus 155 ± 52 mm Hg ; Qs/Qt , 30.2 ± 8.5 % versus 28.1 ± 5.4 % ) . Conclusion : In patients with early extrapulmonary adult respiratory distress syndrome who underwent a PEEP trial , recruitment maneuvers failed to induce a sustained improvement of oxygenation and venous admixture BACKGROUND In patients with the acute respiratory distress syndrome , massive alveolar collapse and cyclic lung reopening and overdistention during mechanical ventilation may perpetuate alveolar injury . We determined whether a ventilatory strategy design ed to minimize such lung injuries could reduce not only pulmonary complications but also mortality at 28 days in patients with the acute respiratory distress syndrome . METHODS We r and omly assigned 53 patients with early acute respiratory distress syndrome ( including 28 described previously ) , all of whom were receiving identical hemodynamic and general support , to conventional or protective mechanical ventilation . Conventional ventilation was based on the strategy of maintaining the lowest positive end-expiratory pressure ( PEEP ) for acceptable oxygenation , with a tidal volume of 12 ml per kilogram of body weight and normal arterial carbon dioxide levels ( 35 to 38 mm Hg ) . Protective ventilation involved end-expiratory pressures above the lower inflection point on the static pressure-volume curve , a tidal volume of less than 6 ml per kilogram , driving pressures of less than 20 cm of water above the PEEP value , permissive hypercapnia , and preferential use of pressure-limited ventilatory modes . RESULTS After 28 days , 11 of 29 patients ( 38 percent ) in the protective-ventilation group had died , as compared with 17 of 24 ( 71 percent ) in the conventional-ventilation group ( P<0.001 ) . The rates of weaning from mechanical ventilation were 66 percent in the protective-ventilation group and 29 percent in the conventional-ventilation group ( P=0.005 ) : the rates of clinical barotrauma were 7 percent and 42 percent , respectively ( P=0.02 ) , despite the use of higher PEEP and mean airway pressures in the protective-ventilation group . The difference in survival to hospital discharge was not significant ; 13 of 29 patients ( 45 percent ) in the protective-ventilation group died in the hospital , as compared with 17 of 24 in the conventional-ventilation group ( 71 percent , P=0.37 ) . CONCLUSIONS As compared with conventional ventilation , the protective strategy was associated with improved survival at 28 days , a higher rate of weaning from mechanical ventilation , and a lower rate of barotrauma in patients with the acute respiratory distress syndrome .  Protective ventilation was not associated with a higher rate of survival to hospital discharge OBJECTIVES To investigate respiratory and hemodynamic changes during lung recruitment and descending optimal positive end-expiratory pressure ( PEEP ) titration . DESIGN Prospect i ve auto-control clinical trial . SETTING Adult general intensive care unit in a university hospital . PATIENTS Eighteen patients with acute respiratory distress syndrome . INTERVENTIONS Following baseline measurements ( T0 ) , PEEP was set at 26 cm H2O and lung recruitment was performed ( 40/40-maneuver ) . Then tidal volume was set at 4 mL/kg ( T26R ) and PEEP was lowered by 2 cm H2O in every 4 mins . Optimal PEEP was defined at 2 cm H2O above the PEEP where Pao2 dropped by > 10 % . After setting the optimal PEEP , the 40/40-maneuver was repeated and tidal volume set at 6 mL/kg ( T(end ) ) . MEASUREMENTS AND MAIN RESULTS Arterial blood gas analysis was done every 4 mins and hemodynamic measurements every 8 mins until T(end ) , then in 30 ( T30 ) and 60 ( T60 ) mins . The Pao2 increased from T0 to T(end ) ( 203 + /- 108 vs. 322 + /- 101 mm Hg , p < .001 ) , but the extravascular lung water ( EVLW ) did not change significantly . Cardiac index ( CI ) and the intrathoracic blood volume ( ITBV ) decreased from T0 to T26R ( CI , 3.90 + /- 1.04 vs. 3.62 + /- 0.91 L/min/m2 , p < .05 ; ITBVI , 832 + /- 205 vs. 795 + /- 188 m/m2 , p < .05 ) . There was a positive correlation between CI and ITBVI ( r = .699 , p < .01 ) , a negative correlation between CI and central venous pressure ( r = -.294 , p < .01 ) , and no correlation between CI and mean arterial pressure ( MAP ) . CONCLUSIONS Following lung recruitment and descending optimal PEEP titration , the Pao2 improves significantly , without any change in the EVLW up to 1 hr . This suggests a decrease in atelectasis as a result of recruitment rather than a reduction of EVLW . There is a significant change in CI during the maneuver , but neither central venous pressure , heart rate , nor MAP can reflect these changes OBJECTIVE To investigate the clinical effects and safety degree of high positive end-expiratory pressure ( PEEP ) combined with lung recruitment maneuver ( RM ) in patients with acute respiratory distress syndrome ( ARDS ) . METHODS Thirty-eight patients in medical intensive care unit ( MICU ) of Affiliated Hospital of Guiyang Medical College suffering from ARDS admitted from June 2008 to May 2010 were enrolled in the study . With the envelope method they were r and omized into RM group and non-RM group , with n=19 in each group . All patients received protective ventilation : pressure support ventilation ( PSV ) with plateau pressure limited at 30 cm H(2)O ( 1 cm H(2)O=0.098 kPa ) or lower . PEEP was set at the minimum level with fraction of inspired oxygen ( FiO(2 ) ) < 0.60 and partial pressure of arterial oxygen ( PaO(2 ) ) kept between 60 and 80 mm Hg ( 1 mm Hg=0.133 kPa ) . RM was conducted by regulating FiO(2 ) to 1.00 , support pressure to 0 , PEEP increased to 40 cm H(2)O and maintained for 30 seconds before lowering , and this maneuver was repeated every 8 hours for a total of 5 days . Base status , ventilation parameters , blood gas analysis and vital signs were obtained at baseline and for the next 5 days . Oxygenation status and lung injury indexes were compared between RM group and non-RM group , the adverse effects of RM and incidence of barotrauma were recorded . RESULTS ¹ There were no significant differences of base status and ventilation parameters between RM group and non-RM group . ²PaO(2 ) and oxygenation index ( PaO(2)/FiO(2 ) ) were both increased in RM group and non-RM group , but the values were higher in RM group [ PaO(2)(mm Hg ) 2 days : 85.8±21.3 vs. 73.5±18.7 , 3 days : 88.6±22.8 vs. 74.3±19.8 , 4 days : 98.8±30.7 vs. 79.3±19.3 , 5 days : 105.5±29.4 vs. 84.4±13.8 ; PaO(2)/FiO(2 ) ( mm Hg ) 4 days : 221.8±103.5 vs. 160.3±51.4 , 5 days : 239.6±69.0 vs. 176.8±45.5 , all P<0.05 ] . ³ Hydrogen peroxide ( H(2)O(2 ) ) and interleukin-6 ( IL-6 ) concentration in exhaled breath condensate ( EBC ) decreased in both groups but lower in RM group with significant difference [ 5 days H(2)O(2 ) ( μmol/L ) : 0.04±0.02 vs. 0.10±0.03 ; IL-6 ( ng/L ) : 4.12±2.09 vs. 9.26±3.47 , both P<0.05 ] . ( 4 ) Barotrauma and arrhythmia did not occur in both groups . No significant changes in heart rate were found during RM . Central venous pressure and mean arterial pressure remained unchanged after RM . CONCLUSION High level PEEP combined with RM can improve gas exchange and oxygenation , decrease ventilator associated lung injury ( VALI ) . RM was safe and had good tolerance , no hypoxemia , barotrauma and hemodynamic instability were observed IMPORTANCE Limited information exists about the epidemiology , recognition , management , and outcomes of patients with the acute respiratory distress syndrome ( ARDS ) . OBJECTIVES To evaluate intensive care unit ( ICU ) incidence and outcome of ARDS and to assess clinician recognition , ventilation management , and use of adjuncts-for example prone positioning-in routine clinical practice for patients fulfilling the ARDS Berlin Definition . DESIGN , SETTING , AND PARTICIPANTS The Large Observational Study to Underst and the Global Impact of Severe Acute Respiratory Failure ( LUNG SAFE ) was an international , multicenter , prospect i ve cohort study of patients undergoing invasive or noninvasive ventilation  , conducted during 4 consecutive weeks in the winter of 2014 in a convenience sample of 459 ICUs from 50 countries across 5 continents . EXPOSURES Acute respiratory distress syndrome . MAIN OUTCOMES AND MEASURES The primary outcome was ICU incidence of ARDS . Secondary outcomes included assessment of clinician recognition of ARDS , the application of ventilatory management , the use of adjunctive interventions in routine clinical practice , and clinical outcomes from ARDS . RESULTS Of 29,144 patients admitted to participating ICUs , 3022 ( 10.4 % ) fulfilled ARDS criteria . Of these , 2377 patients developed ARDS in the first 48 hours and whose respiratory failure was managed with  invasive mechanical ventilation . The period prevalence of mild ARDS was 30.0 % ( 95 % CI , 28.2%-31.9 % ) ; of moderate ARDS , 46.6 % ( 95 % CI , 44.5%-48.6 % ) ; and of severe ARDS , 23.4 % ( 95 % CI , 21.7%-25.2 % ) . ARDS represented 0.42 cases per ICU bed over 4 weeks and represented 10.4 % ( 95 % CI , 10.0%-10.7 % ) of ICU admissions and 23.4 % of patients requiring mechanical ventilation . Clinical recognition of ARDS ranged from 51.3 % ( 95 % CI , 47.5%-55.0 % ) in mild to 78.5 % ( 95 % CI , 74.8%-81.8 % ) in severe ARDS . Less than two-thirds of patients with ARDS received a tidal volume 8 of mL/kg or less of predicted body weight . Plateau pressure was measured in 40.1 % ( 95 % CI , 38.2 - 42.1 ) , whereas 82.6 % ( 95 % CI , 81.0%-84.1 % ) received a positive end-expository pressure ( PEEP ) of less than 12 cm H2O . Prone positioning was used in 16.3 % ( 95 % CI , 13.7%-19.2 % ) of patients with severe ARDS . Clinician recognition of ARDS was associated with higher PEEP , greater use of neuromuscular blockade , and prone positioning . Hospital mortality was 34.9 % ( 95 % CI , 31.4%-38.5 % ) for those with mild , 40.3 % ( 95 % CI , 37.4%-43.3 % ) for those with moderate , and 46.1 % ( 95 % CI , 41.9%-50.4 % ) for those with severe ARDS . CONCLUSIONS AND RELEVANCE Among ICUs in 50 countries , the period prevalence of ARDS was 10.4 % of ICU admissions . This syndrome appeared to be underrecognized and undertreated and associated with a high mortality rate . These findings indicate the potential for improvement in the management of patients with ARDS . TRIAL REGISTRATION clinical trials.gov Identifier : NCT02010073
Background Clinical benefits of recruitment maneuver in ARDS patients are controversial .
A number of previous studies showed possible benefits ; a large recent study reported that recruitment maneuver and PEEP titration may even be harmful .
This meta- analysis was design ed to compare the clinical utility of recruitment maneuver with low tidal volume ventilation in adult patients with ARDS .