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: One hundred twenty patients undergoing coronary artery surgery completed a r and omized controlled study design ed to investigate whether prophylactic chest physiotherapy affected the incidence of postoperative pulmonary complications . Group 1 patients received no preoperative or postoperative chest physiotherapy . Group 2 patients received preoperative education and instruction in breathing and coughing exercises and postoperative supervision and assistance in performing the same . These exercises were supervised by a physiotherapist twice per day on the first 2 postoperative days and once per day on the 3rd and 4th postoperative days . Physiotherapy for group 3 patients was the same as for group 2 patients except that patients were seen by a physiotherapist 4 times per day on the first 2 postoperative days and twice per day on the 3rd and 4th postoperative days . Group 2 and 3 patients were instructed to practice breathing and coughing exercises every hour . Overall , an incidence of clinical ly significant postoperative pulmonary complications of 7.5 percent was demonstrated . In general , these patients demonstrated lower levels of preoperative pulmonary function and very low early postoperative oxygenation compared with those who did not develop pulmonary complications . There was no indication that the incidence or severity of fever , hypoxemia , chest roentgenologic abnormalities or clinical ly significant postoperative pulmonary complications was different between groups . These results suggest that the necessity for prophylactic chest physiotherapy after routine coronary artery surgery should be review ed Abstract  Variability  in patients ' response to interventions in pain and other clinical setting s is large . Many explanations such as trial methods , environment or culture have been proposed , but this paper sets out to show that the main cause of the variability may be r and om chance , and that if trials are small their estimate of magnitude of effect may be incorrect , simply because of the r and om play of chance . This is highly relevant to the questions of ‘ How large do trials have to be for statistical accuracy ? ’ and ‘ How large do trials have to be for their results to be clinical ly valid ? ’ The true underlying control event rate ( CER ) and experimental event rate ( EER ) were determined from single‐dose acute pain analgesic trials in over 5000 patients . Trial group size required to obtain statistically significant and clinical ly relevant ( 0.95 probability of number‐needed‐to‐treat within ±0.5 of its true value ) results were computed using these values . Ten thous and trials using these CER and EER values were simulated using varying group sizes to investigate the variation due to r and om chance alone . Most common analgesics have EERs in the range 0.4–0.6 and CER of about 0.19 . With such efficacy , to have a 90 % chance of obtaining a statistically significant result in the correct direction requires group sizes in the range 30–60 . For clinical relevance nearly 500 patients are required in each group . Only with an extremely effective drug ( EER>0.8 ) will we be reasonably sure of obtaining a clinical ly relevant NNT with commonly used group sizes of around 40 patients per treatment arm . The simulated trials showed substantial variation in CER and EER , with the probability of obtaining the correct values improving as group size increased . We contend that much of the variability in control and experimental event rates is due to r and om chance alone . Single small trials are unlikely to be correct . If we want to be sure of getting correct ( clinical ly relevant ) results in clinical trials we must study more patients . Credible estimates of clinical efficacy are only likely to come from large trials or from pooling multiple trials of conventional ( small ) size OBJECTIVE : Internists frequently evaluate preoperative cardiopulmonary risk and comanage cardiac and pulmonary complications , but the comparative incidence and clinical importance of these complications are not clearly delineated . This study evaluated incidence and length of stay for both cardiac and pulmonary complications after  elective laparotomy .  DESIGN : Nested case-control . SETTING : University-affiliated Department of Veterans Affairs Hospital . PATIENTS : Computerized registry of all 2,291 patients undergoing elective abdominal operations from 1982 to 1991.MEASUREMENT AND MAIN RESULTS : Strategy for ascertainment and verification of complications was systematic and explicit . The charts of all 116 patients identified by the registry as having complications and 412 ( 19 % ) r and omly selected from 2,175 remaining patients were review ed to verify presence or absence of cardiac or pulmonary complications , using explicit criteria and independent abstract ion of pre- and postoperative components of charts . From these 528 vali date d cases and controls ( 23 % of the cohort ) , 96 cases and 96 controls were matched by operation type and age within ten years . Hospital and intensive care unit stays were significantly longer ( p<0.0001 ) for the cases than for the controls ( 24.1 vs 10.3 and 5.8 vs 1.5 days , respectively ) . All 19 deaths occurred among the cases . Among the cases , pulmonary complications occurred significantly more often than cardiac complications ( p<0.00001 ) and were associated with significantly longer hospital stays ( 22.7 vs 10.4 days , p=0.001 ) . Combined cardiopulmonary complications occurred among 26 % of the cases . Misclassification-corrected incidence rates for the entire cohort were 9.6 % ( 95 % CI 7.2–12.0 ) for pulmonary and 5.7 % ( 95 % CI 3.8–7.7 ) for cardiac complications . CONCLUSIONS : For noncardiac surgery , previous research has focused on cardiac risk . In this study , pulmonary complications were more frequent , were associated with longer hospital stay , and occurred in combination with cardiac complications in a substantial proportion of cases . These results suggest that further research is needed to fully characterize the clinical epidemiology of postoperative cardiac and pulmonary complications and better guide preoperative risk assessment The object of the investigation was to compare the effect of three different physiotherapy masks on the incidence of postoperative complications after thoracic surgery . It was carried out as a prospect i ve , consecutive , r and omized comparison at a Department of Thoracic and Heart Surgery at a University Hospital . The therapy was performed by experienced and specially trained physiotherapists . One hundred and sixty patients were evaluated ; 60 patients undergoing heart surgery , 59 patients having pulmonary resection , and 41 patients with exploratory thoracotomy . In each operative category the patients were treated with one of three face mask systems used in addition to routine chest physiotherapy . These were either continuous positive airway pressure ( CPAP ) , positive expiratory pressure ( PEP ) , or inspiratory resistance -- positive expiratory pressure ( IR-PEP ) . Postoperative pulmonary complications were assessed by forced vital capacity ( FVC ) , arterial oxygen tension ( PaO2 ) , and chest X-ray examination , all parameters were measured preoperatively and on the fourth and ninth postoperative day . The patients filled in a question naire concerning their opinions about their mask treatment . IR-PEP showed a lesser decrease in PaO2 on day nine . Otherwise there was an equal decrease in FVC and PaO2 , and equal frequency of atelectasis in the three mask treatments . It is therefore concluded that any of the three therapies : continuous positive airway pressure ( CPAP ) , positive expiratory pressure ( PEP ) , and inspiratory resistance -- positive expiratory pressure ( IR-PEP ) may be used as supplement to st and ard chest physiotherapy BACKGROUND The purpose of this study was to assess the value of tracheal aspirate as a predictor of pneumonia after coronary artery bypass grafting and to evaluate the efficacy of prolonged perioperative antibiotic prophylaxis . METHODS Tracheal aspirates of 500 patients undergoing coronary artery bypass grafting were taken immediately after intubation and analyzed for microorganisms by Gram stain and semiquantitative microbiologic cultures . All patients received 2 g ceftriaxone as a single-dose perioperative antibiotic prophylaxis before operation . Results of Gram stains were available before the patients were transferred to the intensive care unit . After the results were known , both groups of patients ( positive Gram stain , group 1 ; negative Gram stain , group 2 ) were r and omly assigned to either conventional antibiotic prophylaxis ( A ) , consisting of ceftriaxone 2 g on postoperative day 1 , or prolonged antibiotic prophylaxis ( B ) , with ticarcillin + clavulanic acid 3 x 5.2 g during 72 hours . RESULTS From 500 patients , 91 had a positive Gram stain whereas 409 had a negative one . The incidence of pneumonia was significantly higher in patients with preoperative positive tracheal aspirates ( 15.3 % ) than in patients with a negative one ( 3.6 % ; p < 0.01 ) . However , prolonged prophylaxis did not reduce the rate of postoperative pneumonia , which was as high as 13 % in untreated positive patients versus 17 % in treated positive patients , and 2 % in untreated negative patients versus 4 % in treated patients . In patients who had pneumonia , there was a high correlation between the microorganisms found in preoperative aspirates and those observed when aspirates were repeated ( 100 % correlation in patients with conventional antibiotic prophylaxis and 87 % in those with prolonged prophylaxis ) . CONCLUSIONS Early postoperative pneumonia ( < 7 days ) is most likely caused by microorganisms that colonize the respiratory tract before operation . The risk of pulmonary infection after coronary artery bypass grafting can be predicted from the preoperative tracheal aspirates . Prolonged perioperative antibiotic prophylaxis has no efficacy in reducing the incidence of pulmonary infections Forty-nine adults who had undergone cardiopulmonary bypass surgery were r and omly assigned to one of three exercise programs to determine if either maximal inspiratory breathing exercises or incentive spirometry offered a therapeutic advantage over early mobilization alone . After extubation , the patients started their assigned exercise programs . A physical examination and pulmonary function tests were performed preoperatively , at the start of the exercise program , and 24 and 48 hours after the start of the program . The results showed a significant decrease ( approximately 50 % ) in lung volumes but no airflow obstruction in patients who had coronary artery bypass graft . In those patients who had valve replacement , lung volumes fell , and in addition , mild airflow obstruction occurred . A majority of patients had postoperative pulmonary complications . There were no significant differences among the exercise programs in improving lung volumes and airflow or in preventing postoperative complications . We conclude that maximal inspiratory breathing exercises or incentive spirometry , when used in addition to early mobilization , offers no therapeutic advantage over early mobilization alone after cardiopulmonary bypass surgery Objective An investigation into the incidence of post-operative complications after thoracic surgery with  3 different physiotherapy masks . Design A prospect i ve , consecutive , r and omized comparison . Setting Department of Thoracic and Heart Surgery at a University Hospital . The treatments were performed by experienced and specially trained physiotherapists . Patients 160 patients were evaluated . 60 patients undergoing heart surgery , 59 patients having pulmonary resection , and 41 patients with exploratory thoractomy . Interventions In each operative category the patients were treated with one of three face mask systems used in addition to routine chest physiotherapy . These were either continuous positive airway pressure ( CPAP ) , positive expiratory pressure ( PEP ) , or inspiratory resistance — positive expiratory pressure ( IR-PEP ) . Measurements and results Post-operative pulmonary complications were assessed by forced vital capacity ( FVC ) , arterial oxygen tension ( PaO2 ) , and chest X-ray examination , all measured pre-operatively and on the fourth and ninth post-operative day . The patients filled in a question naire expressing their opinion about their mask treatment . There was an equal decrease in FVC , FVC% , and PaO2 , and equal frequency of atelectasis in the 3 mask treatments . More patients with the PEP mask favoured their system than did those with the other 2 systems . Conclusion There was no statistically significant difference between the treatments : continuous positive airway pressure ( CPAP ) , positive expiratory pressure ( PEP ) , and inspiratory resistance — positive expiratory pressure ( IR-PEP ) on post-operative complications . Any of the three treatments may be used as supplement to st and ard chest physiotherapy One hundred and ten men undergoing coronary artery bypass grafting took part in a prospect i ve r and omised study comparing three physiotherapy protocol s. All patients were taught self supported huffing and coughing by a physiotherapist and encouraged to move about . This comprised the sole treatment for the 37 control patients ( group 3 ) . Additional physiotherapy included breathing exercises for the 35 patients in group 1 and use of an incentive spirometer for the 38 patients in group 2 . Functional residual capacity ( FRC ) was measured daily at the bedside until the fifth postoperative day and arterial blood gas tensions were measured on the second and fourth postoperative days . After surgery patients developed a severe restrictive ventilatory defect and profound arterial hypoxaemia . There were no differences between the three groups . Mean FRC on day 2 was 1.90 litres ( 61 % of the preoperative value ) , increasing to 2.32 1 by day 5 ( 76 % of the preoperative value ) . The mean arterial oxygen tension was 7.37 kPa on day 2 and 8.58 kPa on day 4 . Four patients in group 1 , two in group 2 , and five in group 3 developed a chest infection . It is concluded that the addition of breathing exercises or incentive spirometry to a regimen of early 
    Output:
    
agent
The usefulness of respiratory physiotherapy for the prevention of pulmonary complications after cardiac surgery remains unproved .
***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: One hundred twenty patients undergoing coronary artery surgery completed a r and omized controlled study design ed to investigate whether prophylactic chest physiotherapy affected the incidence of postoperative pulmonary complications . Group 1 patients received no preoperative or postoperative chest physiotherapy . Group 2 patients received preoperative education and instruction in breathing and coughing exercises and postoperative supervision and assistance in performing the same . These exercises were supervised by a physiotherapist twice per day on the first 2 postoperative days and once per day on the 3rd and 4th postoperative days . Physiotherapy for group 3 patients was the same as for group 2 patients except that patients were seen by a physiotherapist 4 times per day on the first 2 postoperative days and twice per day on the 3rd and 4th postoperative days . Group 2 and 3 patients were instructed to practice breathing and coughing exercises every hour . Overall , an incidence of clinical ly significant postoperative pulmonary complications of 7.5 percent was demonstrated . In general , these patients demonstrated lower levels of preoperative pulmonary function and very low early postoperative oxygenation compared with those who did not develop pulmonary complications . There was no indication that the incidence or severity of fever , hypoxemia , chest roentgenologic abnormalities or clinical ly significant postoperative pulmonary complications was different between groups . These results suggest that the necessity for prophylactic chest physiotherapy after routine coronary artery surgery should be review ed Abstract  Variability  in patients ' response to interventions in pain and other clinical setting s is large . Many explanations such as trial methods , environment or culture have been proposed , but this paper sets out to show that the main cause of the variability may be r and om chance , and that if trials are small their estimate of magnitude of effect may be incorrect , simply because of the r and om play of chance . This is highly relevant to the questions of ‘ How large do trials have to be for statistical accuracy ? ’ and ‘ How large do trials have to be for their results to be clinical ly valid ? ’ The true underlying control event rate ( CER ) and experimental event rate ( EER ) were determined from single‐dose acute pain analgesic trials in over 5000 patients . Trial group size required to obtain statistically significant and clinical ly relevant ( 0.95 probability of number‐needed‐to‐treat within ±0.5 of its true value ) results were computed using these values . Ten thous and trials using these CER and EER values were simulated using varying group sizes to investigate the variation due to r and om chance alone . Most common analgesics have EERs in the range 0.4–0.6 and CER of about 0.19 . With such efficacy , to have a 90 % chance of obtaining a statistically significant result in the correct direction requires group sizes in the range 30–60 . For clinical relevance nearly 500 patients are required in each group . Only with an extremely effective drug ( EER>0.8 ) will we be reasonably sure of obtaining a clinical ly relevant NNT with commonly used group sizes of around 40 patients per treatment arm . The simulated trials showed substantial variation in CER and EER , with the probability of obtaining the correct values improving as group size increased . We contend that much of the variability in control and experimental event rates is due to r and om chance alone . Single small trials are unlikely to be correct . If we want to be sure of getting correct ( clinical ly relevant ) results in clinical trials we must study more patients . Credible estimates of clinical efficacy are only likely to come from large trials or from pooling multiple trials of conventional ( small ) size OBJECTIVE : Internists frequently evaluate preoperative cardiopulmonary risk and comanage cardiac and pulmonary complications , but the comparative incidence and clinical importance of these complications are not clearly delineated . This study evaluated incidence and length of stay for both cardiac and pulmonary complications after  elective laparotomy .  DESIGN : Nested case-control . SETTING : University-affiliated Department of Veterans Affairs Hospital . PATIENTS : Computerized registry of all 2,291 patients undergoing elective abdominal operations from 1982 to 1991.MEASUREMENT AND MAIN RESULTS : Strategy for ascertainment and verification of complications was systematic and explicit . The charts of all 116 patients identified by the registry as having complications and 412 ( 19 % ) r and omly selected from 2,175 remaining patients were review ed to verify presence or absence of cardiac or pulmonary complications , using explicit criteria and independent abstract ion of pre- and postoperative components of charts . From these 528 vali date d cases and controls ( 23 % of the cohort ) , 96 cases and 96 controls were matched by operation type and age within ten years . Hospital and intensive care unit stays were significantly longer ( p<0.0001 ) for the cases than for the controls ( 24.1 vs 10.3 and 5.8 vs 1.5 days , respectively ) . All 19 deaths occurred among the cases . Among the cases , pulmonary complications occurred significantly more often than cardiac complications ( p<0.00001 ) and were associated with significantly longer hospital stays ( 22.7 vs 10.4 days , p=0.001 ) . Combined cardiopulmonary complications occurred among 26 % of the cases . Misclassification-corrected incidence rates for the entire cohort were 9.6 % ( 95 % CI 7.2–12.0 ) for pulmonary and 5.7 % ( 95 % CI 3.8–7.7 ) for cardiac complications . CONCLUSIONS : For noncardiac surgery , previous research has focused on cardiac risk . In this study , pulmonary complications were more frequent , were associated with longer hospital stay , and occurred in combination with cardiac complications in a substantial proportion of cases . These results suggest that further research is needed to fully characterize the clinical epidemiology of postoperative cardiac and pulmonary complications and better guide preoperative risk assessment The object of the investigation was to compare the effect of three different physiotherapy masks on the incidence of postoperative complications after thoracic surgery . It was carried out as a prospect i ve , consecutive , r and omized comparison at a Department of Thoracic and Heart Surgery at a University Hospital . The therapy was performed by experienced and specially trained physiotherapists . One hundred and sixty patients were evaluated ; 60 patients undergoing heart surgery , 59 patients having pulmonary resection , and 41 patients with exploratory thoracotomy . In each operative category the patients were treated with one of three face mask systems used in addition to routine chest physiotherapy . These were either continuous positive airway pressure ( CPAP ) , positive expiratory pressure ( PEP ) , or inspiratory resistance -- positive expiratory pressure ( IR-PEP ) . Postoperative pulmonary complications were assessed by forced vital capacity ( FVC ) , arterial oxygen tension ( PaO2 ) , and chest X-ray examination , all parameters were measured preoperatively and on the fourth and ninth postoperative day . The patients filled in a question naire concerning their opinions about their mask treatment . IR-PEP showed a lesser decrease in PaO2 on day nine . Otherwise there was an equal decrease in FVC and PaO2 , and equal frequency of atelectasis in the three mask treatments . It is therefore concluded that any of the three therapies : continuous positive airway pressure ( CPAP ) , positive expiratory pressure ( PEP ) , and inspiratory resistance -- positive expiratory pressure ( IR-PEP ) may be used as supplement to st and ard chest physiotherapy BACKGROUND The purpose of this study was to assess the value of tracheal aspirate as a predictor of pneumonia after coronary artery bypass grafting and to evaluate the efficacy of prolonged perioperative antibiotic prophylaxis . METHODS Tracheal aspirates of 500 patients undergoing coronary artery bypass grafting were taken immediately after intubation and analyzed for microorganisms by Gram stain and semiquantitative microbiologic cultures . All patients received 2 g ceftriaxone as a single-dose perioperative antibiotic prophylaxis before operation . Results of Gram stains were available before the patients were transferred to the intensive care unit . After the results were known , both groups of patients ( positive Gram stain , group 1 ; negative Gram stain , group 2 ) were r and omly assigned to either conventional antibiotic prophylaxis ( A ) , consisting of ceftriaxone 2 g on postoperative day 1 , or prolonged antibiotic prophylaxis ( B ) , with ticarcillin + clavulanic acid 3 x 5.2 g during 72 hours . RESULTS From 500 patients , 91 had a positive Gram stain whereas 409 had a negative one . The incidence of pneumonia was significantly higher in patients with preoperative positive tracheal aspirates ( 15.3 % ) than in patients with a negative one ( 3.6 % ; p < 0.01 ) . However , prolonged prophylaxis did not reduce the rate of postoperative pneumonia , which was as high as 13 % in untreated positive patients versus 17 % in treated positive patients , and 2 % in untreated negative patients versus 4 % in treated patients . In patients who had pneumonia , there was a high correlation between the microorganisms found in preoperative aspirates and those observed when aspirates were repeated ( 100 % correlation in patients with conventional antibiotic prophylaxis and 87 % in those with prolonged prophylaxis ) . CONCLUSIONS Early postoperative pneumonia ( < 7 days ) is most likely caused by microorganisms that colonize the respiratory tract before operation . The risk of pulmonary infection after coronary artery bypass grafting can be predicted from the preoperative tracheal aspirates . Prolonged perioperative antibiotic prophylaxis has no efficacy in reducing the incidence of pulmonary infections Forty-nine adults who had undergone cardiopulmonary bypass surgery were r and omly assigned to one of three exercise programs to determine if either maximal inspiratory breathing exercises or incentive spirometry offered a therapeutic advantage over early mobilization alone . After extubation , the patients started their assigned exercise programs . A physical examination and pulmonary function tests were performed preoperatively , at the start of the exercise program , and 24 and 48 hours after the start of the program . The results showed a significant decrease ( approximately 50 % ) in lung volumes but no airflow obstruction in patients who had coronary artery bypass graft . In those patients who had valve replacement , lung volumes fell , and in addition , mild airflow obstruction occurred . A majority of patients had postoperative pulmonary complications . There were no significant differences among the exercise programs in improving lung volumes and airflow or in preventing postoperative complications . We conclude that maximal inspiratory breathing exercises or incentive spirometry , when used in addition to early mobilization , offers no therapeutic advantage over early mobilization alone after cardiopulmonary bypass surgery Objective An investigation into the incidence of post-operative complications after thoracic surgery with  3 different physiotherapy masks . Design A prospect i ve , consecutive , r and omized comparison . Setting Department of Thoracic and Heart Surgery at a University Hospital . The treatments were performed by experienced and specially trained physiotherapists . Patients 160 patients were evaluated . 60 patients undergoing heart surgery , 59 patients having pulmonary resection , and 41 patients with exploratory thoractomy . Interventions In each operative category the patients were treated with one of three face mask systems used in addition to routine chest physiotherapy . These were either continuous positive airway pressure ( CPAP ) , positive expiratory pressure ( PEP ) , or inspiratory resistance — positive expiratory pressure ( IR-PEP ) . Measurements and results Post-operative pulmonary complications were assessed by forced vital capacity ( FVC ) , arterial oxygen tension ( PaO2 ) , and chest X-ray examination , all measured pre-operatively and on the fourth and ninth post-operative day . The patients filled in a question naire expressing their opinion about their mask treatment . There was an equal decrease in FVC , FVC% , and PaO2 , and equal frequency of atelectasis in the 3 mask treatments . More patients with the PEP mask favoured their system than did those with the other 2 systems . Conclusion There was no statistically significant difference between the treatments : continuous positive airway pressure ( CPAP ) , positive expiratory pressure ( PEP ) , and inspiratory resistance — positive expiratory pressure ( IR-PEP ) on post-operative complications . Any of the three treatments may be used as supplement to st and ard chest physiotherapy One hundred and ten men undergoing coronary artery bypass grafting took part in a prospect i ve r and omised study comparing three physiotherapy protocol s. All patients were taught self supported huffing and coughing by a physiotherapist and encouraged to move about . This comprised the sole treatment for the 37 control patients ( group 3 ) . Additional physiotherapy included breathing exercises for the 35 patients in group 1 and use of an incentive spirometer for the 38 patients in group 2 . Functional residual capacity ( FRC ) was measured daily at the bedside until the fifth postoperative day and arterial blood gas tensions were measured on the second and fourth postoperative days . After surgery patients developed a severe restrictive ventilatory defect and profound arterial hypoxaemia . There were no differences between the three groups . Mean FRC on day 2 was 1.90 litres ( 61 % of the preoperative value ) , increasing to 2.32 1 by day 5 ( 76 % of the preoperative value ) . The mean arterial oxygen tension was 7.37 kPa on day 2 and 8.58 kPa on day 4 . Four patients in group 1 , two in group 2 , and five in group 3 developed a chest infection . It is concluded that the addition of breathing exercises or incentive spirometry to a regimen of early 
    Output:
    