***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: A major cause of impaired gas exchange during general anaesthesia is atelectasis , causing pulmonary shunt . A ' vital capacity ' ( VC ) manoeuvre ( i.e. inflation of the lungs up to 40 cm H2O , maintained for 15 s ) may re-exp and atelectasis and improve oxygenation . However , such a manoeuvre may cause adverse cardiovascular effects . Reducing the time of maximal inflation may improve the margin of safety . The aim of this study was to analyse the change over time in the amount of atelectasis during a VC manoeuvre in 12 anaesthetized adults with healthy lungs .  I.v . anaesthesia with controlled mechanical ventilation ( VT 9 ( SD 1 ) ml kg-1 ) was used . For the VC manoeuvre , the lungs were inflated up to an airway pressure ( Paw ) of 40 cm H2O . This pressure was maintained for 26 s. Atelectasis was assessed by analysis of computed x-ray tomography . The amount of atelectasis , measured at the base of the lungs , was 4.0 ( SD 2.7 ) cm2 after induction of anaesthesia . The decrease in the amount of atelectasis over time during the VC manoeuvre was described by a negative exponential function with a time constant of 2.6 s. At an inspired oxygen concentration of 40 % , PaO2 increased from 17.2 ( 4.0 ) kPa before to 22.2 ( 6.0 ) kPa ( P = 0.013 ) after the VC manoeuvre . Thus in anaesthetized adults undergoing mechanical ventilation with healthy lungs , inflation of the lungs to a Paw of 40 cm H2O , maintained for 7 - 8 s only , may re-exp and all previously collapsed lung tissue , as detected by lung computed tomography , and improve oxygenation . We conclude that the previously proposed time for a VC manoeuvre may be halved in such subjects BACKGROUND This study was conducted to determine whether an alveolar recruitment strategy ( ARS ) applied during two-lung ventilation ( TLV ) just before starting one-lung ventilation ( OLV ) improves ventilatory efficiency . METHODS Subjects were r and omly allocated to two groups : ( i ) control group : ventilation with tidal volume ( VT ) of 8 or 6 ml kg(-1 ) for TLV and OLV , respectively , and ( ii )  ARS group : same ventilatory pattern with ARS consisting of 10 consecutive breaths at a plateau pressure of 40 and 20 cm H(2)O PEEP applied immediately before and after OLV . Volumetric capnography and arterial blood sample s  were recorded 5 min ( baseline ) and 20 min into TLV , at 20 and 40 min during OLV , and finally 10 min after re-establishing TLV . RESULTS Twenty subjects were included in each group . In all subjects , the airway component of dead space remained constant during the study . Compared with baseline , the alveolar dead space ratio ( VD(alv)/VT(alv ) ) increased throughout the protocol in the control but decreased in the ARS group . Differences in VD(alv)/VT(alv ) between groups were significant ( P<0.001 ) . Except for baseline , all values in kPa ( sd ) were higher in the ARS than in the control group ( P<0.001 ) , respectively [ 70 ( 7 ) and 55 ( 9 ) ; 33 ( 9 ) and 24 ( 10 ) ; 33 ( 8) and 22 ( 10 ) ; 70 ( 7 ) and 55 ( 10 ) ] . CONCLUSIONS Recruitment of both lungs before instituting OLV not only decreased alveolar dead space but also improved arterial oxygenation and the efficiency of ventilation BACKGROUND : We investigated whether reversal of intraoperative atelectasis with the lung recruitment maneuver ( RM ) affects desflurane arterial concentrations during bariatric surgery . METHODS : After anesthetic induction and maintenance with propofol , patients were r and omized to receive alveolar RM at intervals ( RM group ) or not ( controls ) . Desflurane 6 % was initiated , and rate of increase of alveolar desflurane concentration ( ratio of end-expiratory to inspiratory concentrations , FA/FI ) and desflurane blood concentrations were measured in both groups . Blood and end-tidal desflurane concentrations were also measured after the discontinuation of anesthesia . RESULTS : The RM group had higher intraoperative Pao2/Fio2 compared with the control group ( both , P < 0.001 ) . During induction , the rate of increase in blood desflurane concentrations was rapid in both groups . At comparable mechanical ventilation setting s , median times to achieve 0.5 mM ( approximately 3 % ) were 2.1 and 1.59 min ( P = 0.09 ) in the control and RM group , respectively . The times to achieve 0.7 mM ( approximately 4.2 % ) desflurane were 15.9 and 9.3 min in the control and RM group , respectively ( P = 0.08 ) . Desflurane blood concentrations tended to be higher during the first 30 min after induction in the RM group ( P = 0.066 ) . During maintenance or emergence , the blood desflurane concentrations were not different between control and RM groups . Consequently , the time to eye opening did not differ between groups . CONCLUSION : Although the RM during bariatric surgery represents an effective method for improving intraoperative oxygenation , it does not significantly affect the desflurane blood concentrations during anesthesia or its elimination during emergence Fourteen patients with COPD underwent elective procedures below the umbilicus  , all receiving a st and ard anesthetic . They were r and omized to one of four groups differentiated by the presence or absence of sighing during mechanical ventilation . Patients who were sighed experienced both statistically and clinical ly significant improvement in their oxygenation efficiency as measured by the alveolar to arterial oxygen gradient CONTEXT Hypoxemia complicates the recovery of 30 % to 50 % of patients after abdominal surgery ; endotracheal intubation and mechanical ventilation may be required in 8 % to 10 % of cases , increasing morbidity and mortality and prolonging intensive care unit and hospital stay . OBJECTIVE To determine the effectiveness of continuous positive airway pressure compared with st and ard treatment in preventing the need for intubation and mechanical ventilation in patients who develop acute hypoxemia after elective major abdominal surgery . DESIGN AND SETTING R and omized , controlled , unblinded study with concealed allocation conducted between June 2002 and November 2003 at 15 intensive care units of the Piedmont Intensive Care Units Network in Italy . PATIENTS Consecutive patients who developed severe hypoxemia after major elective abdominal surgery . The trial was stopped for efficacy after 209 patients had been enrolled . INTERVENTIONS Patients were r and omly assigned to receive oxygen ( n = 104 ) or oxygen plus continuous positive airway pressure ( n = 105 ) . MAIN OUTCOME MEASURES The primary end point was incidence of endotracheal intubation ; secondary end points were intensive care unit and hospital lengths of stay , incidence of pneumonia , infection and sepsis , and hospital mortality . RESULTS Patients who received oxygen plus continuous positive airway pressure had a lower intubation rate ( 1 % vs 10 % ; P = .005 ; relative risk [ RR ] , 0.099 ; 95 % confidence interval [ CI ] , 0.01 - 0.76 ) and had a lower occurrence rate of pneumonia ( 2 % vs 10 % , RR , 0.19 ; 95 % CI , 0.04 - 0.88 ; P = .02 ) , infection ( 3 % vs 10 % , RR , 0.27 ; 95 % CI , 0.07 - 0.94 ; P = .03 ) , and sepsis ( 2 % vs 9 % ; RR , 0.22 ; 95 % CI , 0.04 - 0.99 ; P = .03 ) than did patients treated with oxygen alone . Patients who received oxygen plus continuous positive airway pressure also spent fewer mean ( SD ) days in the intensive care unit ( 1.4 [ 1.6 ] vs 2.6 [ 4.2 ] , P = .09 ) than patients treated with oxygen alone . The treatments did not affect the mean ( SD ) days that patients spent in the hospital ( 15 [ 13 ] vs 17 [ 15 ] , respectively ; P = .10 ) . None of those treated with oxygen plus continuous positive airway pressure died in the hospital while 3 deaths occurred among those treated with oxygen alone ( P = .12 ) . CONCLUSION Continuous positive airway pressure may decrease the incidence of endotracheal intubation and other severe complications in patients who develop hypoxemia after elective major abdominal surgery BACKGROUND : The aim of our study was to evaluate the pulmonary and hemodynamic effects of two different recruitment maneuvers after open heart surgery . METHODS : Sixty patients undergoing coronary artery bypass surgery  were r and omized into three groups after operation : recruitment maneuver with continuous positive airway pressure ( CPAP ) ( CPAP-40 group , n = 20 ) , recruitment by positive end-expiratory pressure ( PEEP ) ( PEEP-20 group , n = 20 ) , and 5 cm H2O PEEP ( PEEP-5 group , n = 20 ) . In the CPAP-40 group , 40 cm H2O peak inspiratory pressure was applied for 30 s , then PEEP was reduced to 20 cm H2O and ventilation was continued with baseline variables with PEEP decreased until the best Pao2 was achieved . In the PEEP-20 group , 20 cm H2O PEEP was set for 2 min , tidal volume was adjusted to achieve a peak inspiratory airway pressure of 40 cm H2O during the maneuver , then PEEP was decreased until the best Pao2 had been achieved . In the PEEP-5 group , 5 cm H2O PEEP was applied postoperatively . RESULTS : The mean arterial blood pressure of the CPAP-40 group was lower than that of the PEEP-20 ( P < 0.01 ) and PEEP-5 groups ( P < 0.01 ) during the interventions . Oxygenation was higher in both recruitment groups than in the PEEP-5 group during the mechanical ventilation period . There was no significant difference among the groups beyond that period . The atelectasis score of the PEEP-5 group ( 1.3 ± 0.9 ) on postoperative day 1 was higher than that of the CPAP-40 ( 0.65 ± 0.6 ; P = 0.01 ) and PEEP-20 ( 0.65 ± 0.5 ; P = 0.01 ) groups . CONCLUSIONS : The recruitment techniques with postmaneuver PEEP increased oxygenation and decreased atelectasis equally , whereas PEEP-20 provided more stable hemodynamic conditions than the CPAP maneuver BACKGROUND Lung-protective ventilation with the use of low tidal volumes and positive end-expiratory pressure is considered best practice in the care of many critically ill patients . However , its role in anesthetized patients undergoing major surgery is not known . METHODS In this multicenter , double-blind , parallel-group trial , we r and omly assigned 400 adults at intermediate to high risk of pulmonary complications after major abdominal surgery to either nonprotective mechanical ventilation or a strategy of lung-protective ventilation . The primary outcome was a composite of major pulmonary and extrapulmonary complications occurring within the first 7 days after surgery . RESULTS The two intervention groups had similar characteristics at baseline . In the intention-to-treat analysis , the primary outcome occurred in 21 of 200 patients ( 10.5 % ) assigned to lung-protective ventilation , as compared with 55 of 200 ( 27.5 % ) assigned to nonprotective ventilation ( relative risk , 0.40 ; 95 % confidence interval [ CI ] , 0.24 to 0.68 ; P=0.001 ) . Over the 7-day postoperative period , 10 patients ( 5.0 % ) assigned to lung-protective ventilation required noninvasive ventilation or intubation for acute respiratory failure , as compared with 34 ( 17.0 % ) assigned to nonprotective ventilation ( relative risk , 0.29 ; 95 % CI , 0.14 to 0.61 ; P=0.001 ) . The length of the hospital stay was shorter among patients receiving lung-protective ventilation than among those receiving nonprotective ventilation ( mean difference , -2.45 days ; 95 % CI , -4.17 to -0.72 ; P=0.006 ) . CONCLUSIONS As compared with a practice of nonprotective mechanical ventilation , the use of a lung-protective ventilation strategy in intermediate-risk and high-risk patients undergoing major abdominal surgery was associated with improved clinical outcomes and reduced health care utilization . ( IMPROVE Clinical Trials.gov number , NCT01282996 . ) Objective To assess the safety and efficacy of sustained inflations ( SI ) as lung recruitment maneuvers ( RMs ) in ventilated pediatric intensive care unit ( PICU ) patients . Design Observational , prospect i ve data collection . Setting Tertiary- 
    Output:
    
Subjects in the alveolar recruitment maneuver groups experienced a higher intraoperative PaO2 with improved lung compliance .
Different alveolar recruitment maneuvers were equally effective .
There was a significant advantage when alveolar recruitment maneuvers were followed by PEEP application .
Utilization of alveolar recruitment maneuvers may reduce postoperative pulmonary complications and improve patient outcomes