***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Nosocomial pneumonia develops in 0.5 to 1 patient per 100 hospital admissions and is associated with high morbidity and mortality [ 1 , 2 ] . Mechanically ventilated patients have a high risk for developing nosocomial pneumonia ; indeed , ventilator-associated pneumonia has a cumulative incidence ranging from 18 % to 60 % , and it was found in more than 70 % of patients who died of acute lung injury [ 3 - 6 ] . Nosocomial pneumonia is frequently caused by gram-negative bacilli and usually results from aspiration of bacteria from the colonized oropharynx [ 7 - 9 ] . Colonization of the pharynx by gram-negative bacilli [ 9 - 12 ] is associated with chronic illness and previous use of antibiotic agents and endotracheal intubation ; in the pathogenesis of ventilator-associated pneumonia , the relation between chronic aspiration of colonized secretions through a tracheal cuff and the development of pneumonia is well established [ 13 , 14 ] . Several strategies , such as infection-control measures ( for example , h and -washing ) [ 15 , 16 ] , preservation of a normal gastric pH , or topical administration of a nonabsorbable antibiotic combination ( selective digestive decontamination ) have been recommended to decrease the incidence of ventilator-associated pneumonia [ 17 - 19 ] . However , further investigation is required to define the role of selective digestive decontamination in selected patients in intensive care units ; in addition , there is considerable concern about the risk for selection of resistant strains . Recently , two studies suggested the possibility of preventing the chronic aspiration of subglottic secretions either by changes in body position [ 20 ] or by manual intermittent aspiration of subglottic secretions [ 21 ] , two alternative approaches for preventing ventilator-associated pneumonia . We evaluated the usefulness of continuous aspiration of subglottic secretions in the prevention of ventilator-associated pneumonia in a medicalsurgical intensive care unit . Methods Patients All patients admitted to the intensive care unit of the Sabadell Hospital from June 1990 to March 1993 who required intubation and were expected to receive mechanical ventilation for at least 72 hours were eligible for study . The intubation could be done either in the intensive care unit or in the emergency department . Patients were excluded if they were intubated in other areas of the hospital , if they carried a tracheostomy tube , or if they developed a pneumonia  or died during the first 72 hours of mechanical ventilation . Study was considered complete when a patient was extubated , when a tracheostomy was done , when a patient died , or when ventilator-associated pneumonia was diagnosed . The follow-up period consisted of the patient 's remaining stay in the intensive care unit . All patients were intubated with the same type of endotracheal tube ( Hi-Lo Evac ; Mallinckrodt Laboratories , Athlone , Irel and ) , which incorporates a dorsal separate lumen ending into the subglottic area by creating a large elliptical dorsal opening above the cuff for aspiration of subglottic secretions ( Figure 1 ) . The size of each endotracheal tube was selected by the attending physician ; after intubation , the correct position of endotracheal tube was verified by a roentgenogram of the chest . Figure 1 . Diagram of continuous aspiration of subglottic secretions . Patients were r and omly assigned to receive continuous aspiration through the additional lumen from the endotracheal tube ( case- patients ) or to receive st and ard treatment in which the additional lumen remained closed ( control patients ) . Intra-cuff pressure was monitored every 4 hours ( Mallinckrodt GmbH , Mallinckrodt Laboratories , Neunkirchen-Seelscheid , Germany ) and was kept above 20 mm Hg . Subglottic drainage was continuous , and secretions were collected in a mucous collector ( Mocstrap ; Proclinics , Barcelona , Spain ) . The amount of secretions obtained daily was also recorded . If subglottic drainage was negative , the permeability was checked every 4 hours by injecting sterile saline serum into the evacuation lumen . All patients received stress ulcer prophylaxis with sucralfate . We did not use a selective decontamination regimen or antibiotic prophylaxis . The study protocol was review ed and approved by the hospital 's institutional review board for human studies . Data Collection and Definitions We prospect ively recorded each patient 's demographic characteristics , diagnosis at admission , and underlying diseases . The Acute Physiology and Chronic Health Evaluation ( APACHE ) II scoring system of Knaus and colleagues [ 22 ] was used to assess the severity of an acute illness . Several risk factors for ventilator-associated pneumonia were recorded , such as continuous sedation , previous surgery , multiple trauma , structural or pharmacologic coma ( score of 8 according to the Glasgow coma scale [ 23 ] ) , and use of muscle relaxants and antibiotic treatment during the intensive care unit stay . Ventilator-associated pneumonia was suspected in patients who met the following criteria after 72 hours of mechanical ventilation : fever ( body temperature 38.3 C ) , leukocytosis ( > 12 000 leukocytes/mm3 ) or leukopenia ( < 4000 leukocytes/mm3 ) , purulent secretions , and the presence of new and persistent pulmonary infiltrates . The diagnosis of pneumonia was confirmed by a positive protected specimen brush culture containing 103 colony-forming units (CFU)/mL or more , a positive bronchoalveolar lavage culture with 104 CFU/mL or more , or by a good clinical response to antibiotic agents . Additional criteria were the absence of a diagnosis other than pneumonia and pathologic findings consistent with pneumonia in patients who died and in whom autopsy was authorized . Ventilator-associated pneumonia was histologically diagnosed when foci of consolidation with intense polymorphonuclear leukocyte accumulation in the bronchioles and alveolar spaces were observed . Roentgenograms of the chest were interpreted by a radiologist who had no knowledge of patients ' treatment groups . Crude mortality rates included all deaths that occurred in the intensive care unit in patients with ventilator-associated pneumonia . Death was considered attributable to the pulmonary infection if the patient died before having any objective response to antimicrobial therapy or if the pulmonary infection was considered a contributing factor to death in patients with additional conditions . We used the definitions described by Knaus and colleagues [ 22 ] to define the underlying diseases . We considered previous surgery when a surgical procedure had been done within the present admission to the hospital and considered previous antibiotic treatment when a patient was receiving antibiotic agents at r and omization . Bacteriologic Examination In patients in whom ventilator-associated pneumonia was suspected , bronchoscopy was done while they were being ventilated with an Fio 2 of 1.0 and without positive end-expiratory pressure . All patients received midazolam as a sedative and atracurium as a relaxant while the bronchoscopy was done . The fiberoptic bronchoscope ( Olympus BF 20 ; Olympus Corp. , Tokyo , Japan ) was passed into the trachea through the endotracheal tube by a special connector ( Unimed Ltd. , Shaftesbury , United Kingdom ) and was advanced under visual control to the bronchial orifice of the abnormal lobe . The telescoping plugged catheter ( TAG Medical , Bobigny Cedex , France ) was inserted through the inner suction channel and was advanced to a wedged peripheral position . Airway secretions were obtained using a previously described technique [ 24 ] . For a bronchoalveolar lavage , the bronchoscope was sustained in a wedged position , and lavage was done with three 50-mL aliquots of sterile isotonic saline . The bronchoscope was then removed , and ventilation with an Fio 2 of 1.0 was continued for 15 minutes . After the protected specimen brush was transected into a sterile vial containing 1 mL of sterile lactate Ringer 's solution , the vial was vigorously agitated for at least 60 seconds to suspend all the material from the brush . Specimens were immediately sent to the laboratory for quantitative cultures . Aliquots of 0.01 mL were then taken from the original suspension and inoculated into blood agar , chocolate agar , anaerobic kanamicin blood agar , anaerobic blood agar , MacConkey agar , buffered charcoal yeast extract agar , and Sabouraud media . One 0.001-mL aliquot was also inoculated into chocolate agar media . Culture plates were incubated at 37 C under adequate aerobic and anaerobic conditions ; all plates except for the Sabouraud plates were evaluated for growth at 24 and 48 hours . For the protected specimen brush , bacterial counts of 103 CFU/mL or greater were used as the cutoff point to diagnose pneumonia . Two serial 10-fold dilutions were then done on the recovered bronchoalveolar lavage fluid , and 0.01-mL aliquots of the original suspension and each dilution were placed onto plates in the same way as for the protected specimen brush sample . All protected specimen brush and bronchoalveolar lavage fluid isolates were identified by st and ard laboratory techniques [ 25 ] . Two blood cultures were done simultaneously in all patients , as were pleural fluid cultures if present . Surveillance cultures for aerobic microorganisms in the subglottic secretions were obtained from patients in the continuous aspiration group and were repeated every 5 days until ventilator-associated pneumonia developed or until patients were extubated or died . Statistical Analysis We compared the characteristics of the two groups using the Student t-test or Mann-Whitney test for continuous variables and the chi-square test or Fisher exact test for categorical variables . We defined the cumulative incidence as the number of events divided by the number of patients and estimated risk ratios and 95 % CIs [ 26 ] . The incidence rate was defined as the number of events divided by the number of days the patient was at risk because of the presence of an endotracheal tube . We compared Objective To evaluate the impact of continuous subglottic suctioning and semi-recumbent body position on bacterial colonisation of the lower respiratory tract . Design A r and omised controlled trial . Setting The ten-bed medical ICU of a French university hospital . Patients Critically ill patients expected to require mechanical ventilation for more than 5 days . Interventions Patients were r and omly assigned to receive either continuous suctioning of subglottic secretions and semi-recumbent body position or to receive st and ard care and supine position . Measurements and results Oropharyngeal and tracheal secretions were sample d daily and quantitatively cultured . All included patients were followed up from day 1 ( intubation ) to day 10 , extubation or death . Ninety-seven sample s of oropharynx and trachea were analysed ( 40 for the suctioning group and 57 for the control group ) . The median bacterial counts in trachea were 6.6 Log10 CFU/ml ( interquartile range , IQR , 4.4–8.3 ) in patients who received continuous suctioning and 5.1 Log10 CFU/ml ( IQR 3.6–5.5 ) in control patients . Most of the patients were colonised in the trachea after 1 day of mechanical ventilation ( 75 % in the suctioning group , 80 % in the control group ) . No significant difference was found in the daily bacterial counts in the oropharynx and in the trachea between the two groups of patients . Conclusion Tracheal colonisation in long-term mechanically ventilated ICU patients was not modified by the use of continuous subglottic suctioning and semi-recumbent body position OBJECTIVE To evaluate the effect of continuous aspiration of subglottic secretions ( CASS ) on the prevention of ventilator-associated pneumonia ( VAP )  in mechanically ventilated patients . METHODS Patients ventilated mechanically at the ICU from October , 2004 to April , 2006 were r and omly divided into 2 groups : one group received CASS and the other did not ( NASS group ) . CASS was performed immediately after admission for patients in the CASS group . The diagnosis of VAP was made based on clinical presentations , and the evaluation of VAP was done using simplified version of the clinical pulmonary infection score ( CPIS ) . The general status of the patients , days of ventilated treatment , the volume of daily aspirated subglottic secretions , the morbidity and timing of VAP , days of stay in ICU and mortality within 28 days of hospitalization were recorded . RESULTS One hundred and one patients were included in the study . There were 48 patients in the CASS group who were treated with mechanical ventilation more than 48 hours , and 43 patients in the NASS group . There was no significant difference in the general status of the patients and days of ventilation between 2 groups with the averaged score of APACHE II being 20.8 + /- 6.1 . The average of CPIS was of 5.6 + /- 1.0 when VAP was diagnosed . The mean volume of aspirated subglottic secretions within the first 24 hours in the CASS group ( n = 48 ) was ( 27.2 + /- 21.2 ) ml . The morbidity of VAP in the CASS and the NASS groups was 25.0 % and 46.5 % respectively ( P = 0.032 ) , and the length of time before the onset of VAP in these 2 groups was ( 7.3 + /- 4.2 ) days and ( 5.1 + /- 3.0 
    Output:
    
There were no significant differences between groups in stridor or reintubations .
CONCLUSIONS Subglottic secretion drainage is associated with lower ventilator-associated pneumonia rates but does not clearly decrease duration of mechanical ventilation , length of stay , ventilator-associated events , mortality , or antibiotic usage .