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: Objective To examine whether postoperative mechanical ventilation with lower tidal volumes ( VT ) has protective effects on inflammatory responses induced by  cardiopulmonary bypass ( CPB )  surgery in smokers and nonsmokers . Design and setting Prospect i ve , r and omized , controlled clinical trial in the intensive care unit of a university hospital . Patients and participants We examined 44 patients ( 22 smokers , 22 nonsmokers ) immediately after uncomplicated CPB surgery . Interventions Ventilation was applied for 6 h with either VT of either 6 or 12 ml/kg ideal body weight . Measurements and results The time course of serum tumor necrosis factor ( TNF ) α , interleukin ( IL ) 6 , and IL-8 determined 0 , 2 , 4 , and 6 h after r and omization did not differ significantly between the ventilatory strategies . By contrast , in bronchoalveolar lavage fluids sample d after 6 h only TNF-α levels were significantly higher in the high VT group than the low VT group ( 50±111 pg/ml vs. 1±7 pg/ml ) . IL-6 and IL-8 concentrations did not differ between groups . Subgroup analysis of patients with serum TNF-α level higher than 0 pg/ml after surgery revealed lower TNF-α serum levels during lower VT ventilation . All observed effects were small , independent of patients ’ history of smoking , and were not correlated with duration of ventilation and ICU stay . Conclusions Ventilation with lower VT had no or only minor effect on systemic and pulmonary inflammatory responses in patients with healthy lungs after uncomplicated CPB surgery . Our data do not suggest a clinical benefit of using low VT ventilation in these selected patients Introduction In lung cancer surgery , large tidal volume and elevated inspiratory pressure are known risk factors of acute lung ( ALI ) . Mechanical ventilation with low tidal volume has been shown to attenuate lung injuries in critically ill patients . In the current study , we assessed the impact of a protective lung ventilation ( PLV ) protocol in patients undergoing lung cancer resection . Methods We performed a secondary analysis of an observational cohort . Demographic , surgical , clinical and outcome data were prospect ively collected over a 10-year period . The PLV protocol consisted of small tidal volume , limiting maximal pressure ventilation and adding end-expiratory positive pressure along with recruitment maneuvers . Multivariate analysis with logistic regression was performed and data were compared before and after implementation of the PLV protocol : from 1998 to 2003 ( historical group , n = 533 ) and from 2003 to 2008 ( protocol group , n = 558 ) . Results Baseline patient characteristics were similar in the two cohorts , except for a higher cardiovascular risk profile in the intervention group . During one-lung ventilation , protocol -managed patients had lower tidal volume ( 5.3 ± 1.1 vs. 7.1 ± 1.2 ml/kg in historical controls , P = 0.013 ) and higher dynamic compliance ( 45 ± 8 vs. 32 ± 7 ml/cmH2O , P = 0.011 ) . After implementing PLV , there was a decreased incidence of acute lung injury ( from 3.7 % to 0.9 % , P < 0.01 ) and atelectasis ( from 8.8 to 5.0 , P = 0.018 ) , fewer admissions to the intensive care unit ( from 9.4 % vs. 2.5 % , P < 0.001 ) and shorter hospital stay ( from 14.5 ± 3.3 vs. 11.8 ± 4.1 , P < 0.01 ) . When adjusted for baseline characteristics , implementation of the open-lung protocol was associated with a reduced risk of acute lung injury ( adjusted odds ratio of 0.34 with 95 % confidence interval of 0.23 to 0.75 ; P = 0.002 ) . Conclusions Implementing an intraoperative PLV protocol in patients undergoing lung cancer resection was associated with improved postoperative respiratory outcomes as evidence by significantly reduced incidences of acute lung injury and atelectasis along with reduced utilization of intensive care unit re sources STUDY OBJECTIVE To determine whether low tidal ventilation in patients without lung injury results in an increase in the amount of atelectasis and a further impairment of gas exchange during general anesthesia . DESIGN R and omized , single-blind study . SETTING University hospital . PATIENTS 16 adult , ASA physical status I and II patients , who were scheduled for elective excision of intracranial lesion . INTERVENTIONS Patients were r and omly allocated to one of two groups : traditional tidal volume ( V(T ) ) ventilation group ( V(T ) , 10 mL/kg ) and low V(T ) ventilation group ( V(T ) , 6 mL/kg ) after the first computed tomographic ( CT ) scan . MEASUREMENTS AND MAIN RESULTS Atelectasis , as determined by CT and arterial blood gas analysis , was measured before induction , after tracheal intubation , and at the end of operation . After tracheal intubation , CT scan showed atelectasis in both groups . The mean atelectasis area was 4.25 + /- 2.05 cm(2 ) ( 3.32 % + /- 1.94 % ) in the traditional V(T ) ventilation group and 5.56 + /- 3.21 cm(2 ) ( 4.19 % + /- 2.31 % ) in the low V(T ) ventilation group . At the end of operation , there was no significant increase in the amount of atelectasis within the two groups . Arterial blood gas analysis showed no differences after tracheal intubation or at the end of operation in either group . CONCLUSION Ventilation using low V(T)s does not cause more pulmonary collapse than mechanical ventilation using st and ard V(T)s Background : The impact of intraoperative ventilation on postoperative pulmonary complications is not defined . The authors aim ed at determining the effectiveness of protective mechanical ventilation during open abdominal surgery on a modified Clinical Pulmonary Infection Score as primary outcome and postoperative pulmonary function . Methods : Prospect i ve r and omized , open-label , clinical trial performed in 56 patients scheduled to undergo elective open abdominal surgery lasting more than 2 h. Patients were assigned by envelopes to mechanical ventilation with tidal volume of 9 ml/kg ideal body weight and zero-positive end-expiratory pressure ( st and ard ventilation strategy ) or tidal volumes of 7 ml/kg ideal body weight , 10 cm H2O positive end-expiratory pressure , and recruitment maneuvers ( protective ventilation strategy ) . Modified Clinical Pulmonary Infection Score , gas exchange , and pulmonary functional tests were measured preoperatively , as well as at days 1 , 3 , and 5 after surgery . Results : Patients ventilated protectively showed better pulmonary functional tests up to day 5 , fewer alterations on chest x-ray up to day 3 and higher arterial oxygenation in air at days 1 , 3 , and 5 ( mmHg ; mean ± SD ) : 77.1 ± 13.0 versus 64.9 ± 11.3 ( P = 0.0006 ) , 80.5 ± 10.1 versus 69.7 ± 9.3 ( P = 0.0002 ) , and 82.1 ± 10.7 versus 78.5 ± 21.7 ( P = 0.44 ) respectively . The modified Clinical Pulmonary Infection Score was lower in the protective ventilation strategy at days 1 and 3 . The percentage of patients in hospital at day 28 after surgery was not different between groups ( 7 vs. 15 % respectively , P = 0.42 ) . Conclusion : A protective ventilation strategy during abdominal surgery lasting more than 2 h improved respiratory function and reduced the modified Clinical Pulmonary Infection Score without affecting length of hospital stay BACKGROUND Minimally invasive esophagectomy ( MIE ) has been advantageous for lowering pulmonary complications compared with open approaches.(1 ) However , pulmonary complications remain the most common morbidity after surgical resection of esophageal cancer.(2,3 ) The aim of this prospect i ve , r and omized , controlled , clinical trial was design ed to see whether low tidal volume ( VT ) could further minimize pulmonary complications after MIE . METHODS Between June 2011 and July 2012 , a total of 101 patients who underwent MIE received left-lung ventilation during thoracoscopic esophagectomy .  All patients received left-lung ventilation during thoracoscopic esophagectomy . Patients were r and omly assigned to a low VT ( 5 mL/kg + 5 cm H2O positive end-expiratory pressure ) preserved ventilation ( PV ) group ( n = 53 ) and a conventional VT ( 8 mL/kg ) controlled ventilation ( CV ) group ( n = 48 ) in the thoracic stage . Alveolar lavage fluid was harvested from the ventilated lung at intubation and at 18 hours after surgery for analysis of interleukin (IL)-1ß , IL-6 , and IL-8 levels . Clinical characteristics , including patient demographics , operation features , and changes in oxygenation index , were recorded and analyzed . Pulmonary complications were identified and statistically compared between the 2 groups . RESULTS The clinical characteristics and operation features were comparable between the 2 groups . IL-1ß , IL-6 , and IL-8 expressions in preoperative alveolar lavage fluid were similar between the 2 groups . Significantly lower IL expressions were observed in the PV group than those in the CV group at 18 hours after MIE ( IL-1ß , 25.42 ± 31.01 vs 94.96 ± 118.24 pg/mL ; IL-6 , 30.86 ± 75.78 vs 92.99 ± 72.90 pg/mL ; IL-8 , 258.75 ± 188.24 vs 403.95 ± 151.44 pg/mL ; all P < .05 ) . The 18-hour postoperative oxygenation index was lower in the CV group than that in the PV group ( 292.85 ± 28.74 vs 326.35 ± 34.43 ; P = .046 ) . Pulmonary complications were observed in 18 cases of our series , occurring more frequently on the ventilation side ( right , 6 cases ; and left , 12 cases ) . All patients were cured by conservative therapy without severe sequelae . The occurrence of pulmonary complications in the PV group was lower than that in the CV group ( 9.43 % vs 27.08 % ; P = .021 ) . CONCLUSIONS Lung injury due to intraoperative single-lung ventilation may contribute to pulmonary complications after MIE . Low VT ventilation could decrease ventilation-associated lung inflammation , thus minimizing pulmonary complications after MIE . Further studies , based on a larger volume of population s , are required to confirm these findings 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 RATIONALE Baseline characteristics and management have changed over time in patients requiring mechanical ventilation ;  however , the impact of these changes on patient outcomes is unclear . OBJECTIVES To estimate whether mortality in mechanically ventilated patients has changed over time . METHODS Prospect i ve cohort studies conducted in 1998 , 2004 , and 2010 , 
    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: Objective To examine whether postoperative mechanical ventilation with lower tidal volumes ( VT ) has protective effects on inflammatory responses induced by  cardiopulmonary bypass ( CPB )  surgery in smokers and nonsmokers . Design and setting Prospect i ve , r and omized , controlled clinical trial in the intensive care unit of a university hospital . Patients and participants We examined 44 patients ( 22 smokers , 22 nonsmokers ) immediately after uncomplicated CPB surgery . Interventions Ventilation was applied for 6 h with either VT of either 6 or 12 ml/kg ideal body weight . Measurements and results The time course of serum tumor necrosis factor ( TNF ) α , interleukin ( IL ) 6 , and IL-8 determined 0 , 2 , 4 , and 6 h after r and omization did not differ significantly between the ventilatory strategies . By contrast , in bronchoalveolar lavage fluids sample d after 6 h only TNF-α levels were significantly higher in the high VT group than the low VT group ( 50±111 pg/ml vs. 1±7 pg/ml ) . IL-6 and IL-8 concentrations did not differ between groups . Subgroup analysis of patients with serum TNF-α level higher than 0 pg/ml after surgery revealed lower TNF-α serum levels during lower VT ventilation . All observed effects were small , independent of patients ’ history of smoking , and were not correlated with duration of ventilation and ICU stay . Conclusions Ventilation with lower VT had no or only minor effect on systemic and pulmonary inflammatory responses in patients with healthy lungs after uncomplicated CPB surgery . Our data do not suggest a clinical benefit of using low VT ventilation in these selected patients Introduction In lung cancer surgery , large tidal volume and elevated inspiratory pressure are known risk factors of acute lung ( ALI ) . Mechanical ventilation with low tidal volume has been shown to attenuate lung injuries in critically ill patients . In the current study , we assessed the impact of a protective lung ventilation ( PLV ) protocol in patients undergoing lung cancer resection . Methods We performed a secondary analysis of an observational cohort . Demographic , surgical , clinical and outcome data were prospect ively collected over a 10-year period . The PLV protocol consisted of small tidal volume , limiting maximal pressure ventilation and adding end-expiratory positive pressure along with recruitment maneuvers . Multivariate analysis with logistic regression was performed and data were compared before and after implementation of the PLV protocol : from 1998 to 2003 ( historical group , n = 533 ) and from 2003 to 2008 ( protocol group , n = 558 ) . Results Baseline patient characteristics were similar in the two cohorts , except for a higher cardiovascular risk profile in the intervention group . During one-lung ventilation , protocol -managed patients had lower tidal volume ( 5.3 ± 1.1 vs. 7.1 ± 1.2 ml/kg in historical controls , P = 0.013 ) and higher dynamic compliance ( 45 ± 8 vs. 32 ± 7 ml/cmH2O , P = 0.011 ) . After implementing PLV , there was a decreased incidence of acute lung injury ( from 3.7 % to 0.9 % , P < 0.01 ) and atelectasis ( from 8.8 to 5.0 , P = 0.018 ) , fewer admissions to the intensive care unit ( from 9.4 % vs. 2.5 % , P < 0.001 ) and shorter hospital stay ( from 14.5 ± 3.3 vs. 11.8 ± 4.1 , P < 0.01 ) . When adjusted for baseline characteristics , implementation of the open-lung protocol was associated with a reduced risk of acute lung injury ( adjusted odds ratio of 0.34 with 95 % confidence interval of 0.23 to 0.75 ; P = 0.002 ) . Conclusions Implementing an intraoperative PLV protocol in patients undergoing lung cancer resection was associated with improved postoperative respiratory outcomes as evidence by significantly reduced incidences of acute lung injury and atelectasis along with reduced utilization of intensive care unit re sources STUDY OBJECTIVE To determine whether low tidal ventilation in patients without lung injury results in an increase in the amount of atelectasis and a further impairment of gas exchange during general anesthesia . DESIGN R and omized , single-blind study . SETTING University hospital . PATIENTS 16 adult , ASA physical status I and II patients , who were scheduled for elective excision of intracranial lesion . INTERVENTIONS Patients were r and omly allocated to one of two groups : traditional tidal volume ( V(T ) ) ventilation group ( V(T ) , 10 mL/kg ) and low V(T ) ventilation group ( V(T ) , 6 mL/kg ) after the first computed tomographic ( CT ) scan . MEASUREMENTS AND MAIN RESULTS Atelectasis , as determined by CT and arterial blood gas analysis , was measured before induction , after tracheal intubation , and at the end of operation . After tracheal intubation , CT scan showed atelectasis in both groups . The mean atelectasis area was 4.25 + /- 2.05 cm(2 ) ( 3.32 % + /- 1.94 % ) in the traditional V(T ) ventilation group and 5.56 + /- 3.21 cm(2 ) ( 4.19 % + /- 2.31 % ) in the low V(T ) ventilation group . At the end of operation , there was no significant increase in the amount of atelectasis within the two groups . Arterial blood gas analysis showed no differences after tracheal intubation or at the end of operation in either group . CONCLUSION Ventilation using low V(T)s does not cause more pulmonary collapse than mechanical ventilation using st and ard V(T)s Background : The impact of intraoperative ventilation on postoperative pulmonary complications is not defined . The authors aim ed at determining the effectiveness of protective mechanical ventilation during open abdominal surgery on a modified Clinical Pulmonary Infection Score as primary outcome and postoperative pulmonary function . Methods : Prospect i ve r and omized , open-label , clinical trial performed in 56 patients scheduled to undergo elective open abdominal surgery lasting more than 2 h. Patients were assigned by envelopes to mechanical ventilation with tidal volume of 9 ml/kg ideal body weight and zero-positive end-expiratory pressure ( st and ard ventilation strategy ) or tidal volumes of 7 ml/kg ideal body weight , 10 cm H2O positive end-expiratory pressure , and recruitment maneuvers ( protective ventilation strategy ) . Modified Clinical Pulmonary Infection Score , gas exchange , and pulmonary functional tests were measured preoperatively , as well as at days 1 , 3 , and 5 after surgery . Results : Patients ventilated protectively showed better pulmonary functional tests up to day 5 , fewer alterations on chest x-ray up to day 3 and higher arterial oxygenation in air at days 1 , 3 , and 5 ( mmHg ; mean ± SD ) : 77.1 ± 13.0 versus 64.9 ± 11.3 ( P = 0.0006 ) , 80.5 ± 10.1 versus 69.7 ± 9.3 ( P = 0.0002 ) , and 82.1 ± 10.7 versus 78.5 ± 21.7 ( P = 0.44 ) respectively . The modified Clinical Pulmonary Infection Score was lower in the protective ventilation strategy at days 1 and 3 . The percentage of patients in hospital at day 28 after surgery was not different between groups ( 7 vs. 15 % respectively , P = 0.42 ) . Conclusion : A protective ventilation strategy during abdominal surgery lasting more than 2 h improved respiratory function and reduced the modified Clinical Pulmonary Infection Score without affecting length of hospital stay BACKGROUND Minimally invasive esophagectomy ( MIE ) has been advantageous for lowering pulmonary complications compared with open approaches.(1 ) However , pulmonary complications remain the most common morbidity after surgical resection of esophageal cancer.(2,3 ) The aim of this prospect i ve , r and omized , controlled , clinical trial was design ed to see whether low tidal volume ( VT ) could further minimize pulmonary complications after MIE . METHODS Between June 2011 and July 2012 , a total of 101 patients who underwent MIE received left-lung ventilation during thoracoscopic esophagectomy .  All patients received left-lung ventilation during thoracoscopic esophagectomy . Patients were r and omly assigned to a low VT ( 5 mL/kg + 5 cm H2O positive end-expiratory pressure ) preserved ventilation ( PV ) group ( n = 53 ) and a conventional VT ( 8 mL/kg ) controlled ventilation ( CV ) group ( n = 48 ) in the thoracic stage . Alveolar lavage fluid was harvested from the ventilated lung at intubation and at 18 hours after surgery for analysis of interleukin (IL)-1ß , IL-6 , and IL-8 levels . Clinical characteristics , including patient demographics , operation features , and changes in oxygenation index , were recorded and analyzed . Pulmonary complications were identified and statistically compared between the 2 groups . RESULTS The clinical characteristics and operation features were comparable between the 2 groups . IL-1ß , IL-6 , and IL-8 expressions in preoperative alveolar lavage fluid were similar between the 2 groups . Significantly lower IL expressions were observed in the PV group than those in the CV group at 18 hours after MIE ( IL-1ß , 25.42 ± 31.01 vs 94.96 ± 118.24 pg/mL ; IL-6 , 30.86 ± 75.78 vs 92.99 ± 72.90 pg/mL ; IL-8 , 258.75 ± 188.24 vs 403.95 ± 151.44 pg/mL ; all P < .05 ) . The 18-hour postoperative oxygenation index was lower in the CV group than that in the PV group ( 292.85 ± 28.74 vs 326.35 ± 34.43 ; P = .046 ) . Pulmonary complications were observed in 18 cases of our series , occurring more frequently on the ventilation side ( right , 6 cases ; and left , 12 cases ) . All patients were cured by conservative therapy without severe sequelae . The occurrence of pulmonary complications in the PV group was lower than that in the CV group ( 9.43 % vs 27.08 % ; P = .021 ) . CONCLUSIONS Lung injury due to intraoperative single-lung ventilation may contribute to pulmonary complications after MIE . Low VT ventilation could decrease ventilation-associated lung inflammation , thus minimizing pulmonary complications after MIE . Further studies , based on a larger volume of population s , are required to confirm these findings 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 RATIONALE Baseline characteristics and management have changed over time in patients requiring mechanical ventilation ;  however , the impact of these changes on patient outcomes is unclear . OBJECTIVES To estimate whether mortality in mechanically ventilated patients has changed over time . METHODS Prospect i ve cohort studies conducted in 1998 , 2004 , and 2010 , 
    Output:
    