***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: In normal adults , both blood flow and ventilation are distributed preferentially to the dependent lung zones . In adults with unilateral lung disease , arterial oxygenation improves when they are positioned with their good lung down because of improved matching of ventilation and perfusion . When the closing volume is increased , dependent airways are closed during tidal breathing , so that reduced ventilation-perfusion ratio and hypoxia develops and ventilation is preferentially distributed to the upper lung zones . We undertook an observational study on the effects of lateral recumbency on arterial oxygenation in adult patients with unilateral lung disease and tested the hypothesis that oxygenation in lateral recumbency might be influenced by an increase in closing volume . Arterial blood gases were analyzed in the supine , right and left lateral decubitus positions and the AaPO(2 ) was calculated in 44 r and omly selected patients 49.9 + /- 18.7 yr of age with unilateral pneumonia ( 23 cases ) or pulmonary tuberculosis ( 21 cases ) . In 26 patients , individual Pa(O(2 ) ) with the normal lung in the dependent position was higher than that with the diseased lung ; the opposite was true for 18 patients . The difference in Pa(O(2 ) ) and AaPO(2 ) between the two positions was statistically significant in both groups . In 16 patients ( 10 men and six women 49.2 + /- 18.2 yr of age ) , we measured closing volume and determined the fractional ventilation to each lung by (133)Xe lung scan in the three positions . In these 16 patients , the difference in Pa(O(2 ) ) between the normal and the diseased lung in the dependent position was related significantly to the difference in the fractional ventilation going to the normal lung between the dependent and the supine position ( r = 0.642 , p = 0 . 007 ) . The latter was related significantly to the % predicted closing volume ( CV/VC ) ( r = -0.597 , p = 0.015 ) . This study has shown that closing volume , as well as posture , might be involved in determining oxygenation in lateral recumbency in patients with unilateral lung disease Objective The routine turning of immobilized critically ill patients at a minimum of every 2 hrs has become the accepted st and ard of care . There has never been an objective assessment of whether this st and ard is achieved routinely . To determine if immobilized patients in the intensive care unit ( ICU ) receive the prevailing st and ard of change in body position every 2 hrs . To determine prevailing attitudes about patient positioning among ICU physicians . Design Prospect i ve longitudinal observational study . E-mail survey of ICU physicians . Setting and Participants Convenience sample of mixed medical/surgical ICU patients at three tertiary care hospitals in two different cities in the United States . R and om sampling of ICU professionals from a directory . Main Outcome Measures Changes in body position recorded at 15-min intervals . Results Seventy-four patients were observed for a total of 566 total patient hours of observation , with a mean observation time per patient of 7.7 hrs ( range , 5–12 ) . On average , 49.3 % of the observed time , patients remained without a change in body position for > 2 hrs . Only two of 74 patients ( 2.7 % ) had a demonstrable change in body position every 2 hrs . A total of 80–90 % of respondents to the survey agreed that turning every 2 hrs was the accepted st and ard and that it prevented complications , but only 57 % believed it was being achieved in their ICUs . Conclusions The majority of critically ill patients may not be receiving the prevailing st and ard of changes in body position every 2 hrs . This warrants a re appraisal of our care of critically ill patients In the era of evidence -based practice ( EBP ) , R and omized Controlled Trials ( RCTs ) may provide the best evidence of the efficacy of nursing interventions and yet the quality of RCT reporting in nursing literature has not been evaluated . The purpose s of this study were to apply the Consoli date d St and ards of Reporting Trials ( CONSORT ) statement to published reports of nursing science , examine how adequately the published reports adhere to the statement , and examine the effect of the adoption of CONSORT on the quality of the RCT published reports . One hundred RCTs from 2002 - 2005 were identified from 4 nursing journals . Articles were r and omly assigned to 4 review ers and the quality of the published reports was evaluated using a modified CONSORT checklist . There was no difference between the 4 journals in the quality of the published reports of RCTs based on the modified CONSORT checklist employed ( F = 1.27 , P = .29 ) . The quality of reporting of RCTs improved significantly in the only journal , Nursing Research , to adopt the CONSORT statement during the study period ( t = -2.70 , P = .01 ) . Adoption of CONSORT is recommended as it may lead to an overall improvement in quality of reporting of RCTs in nursing journals . The profession may also wish to explore the use or development of st and ards similar to CONSORT but ones more appropriate for the types of research typical of that published by nurse scientists Background Routine turning of critically ill patients is a st and ard of care . In recent years , specialized beds that provide automated turning have been introduced . These beds have been reported to improve lung function , reduce hospital-acquired pneumonia , and facilitate secretion removal . This trial was design ed to measure the physiological effects of routine turning and respiratory therapy in comparison with continuous lateral rotation ( CLR ) . Methods The study was a prospect i ve , quasi-experimental , r and om assignment , trial with patients serving as their own controls . Paralyzed , se date d patients with acute respiratory distress syndrome were eligible for study . Patients were r and omized to receive four turning and secretion management regimens in r and om sequence for 6 h each over a period of 24 h : ( 1 ) routine turning every 2 h from the left to right lateral position ; ( 2 ) routine turning every 2 h from the left to right lateral position including a 15-min period of manual percussion and postural drainage ( P&PD ) ; ( 3 ) CLR with a specialized bed that turned patients from left to right lateral position , pausing at each position for 2 min ; and ( 4 ) CLR with a specialized bed that turned patients from left to right lateral position pausing at each position for 2 min , and a 15-min period of percussion provided by the pneumatic cushions of the bed every 2 h. Results Nineteen patients were entered into the study . There were no statistically significant differences in the measured cardiorespiratory variables . There was a tendency for the ratio of partial pressure of arterial oxygen to fractional inspired oxygen concentration ( PaO2/FIO2 ) to increase ( 174 ± 31 versus 188 ± 36 ; P = 0.068 ) and for the ratio of deadspace to tidal volume ( Vd/Vt ) to decrease ( 0.62 ± 0.18 versus 0.59 ± 0.18 ; P = 0.19 ) during periods of CLR , but these differences did not achieve statistical significance . There were statistically significant increases in sputum volume during the periods of CLR . The addition of P&PD did not increase sputum volume for the group as a whole . However , in the four patients producing more than 40 ml of sputum per day , P&PD increased sputum volume significantly . The number of patient turns increased from one every 2 h to one every 10 min during CLR . Conclusion The acute effects of CLR are undoubtedly different in other patient population s ( spinal cord injury and unilateral lung injury ) . The link between acute physiological changes and improved outcomes associated with CLR remain to be determined BACKGROUND Optimal turning of critically ill patients is not well established . Kinetic therapy ( systematic mechanical rotation of patients with 40 degree turns ) may improve pulmonary function more than the improvement in function achieved via the st and ard of care ( turning patients every 2 hours ) . OBJECTIVE To determine ( 1 ) if patients receiving mechanical ventilation who tolerate kinetic therapy  have better pulmonary function than do patients treated with st and ard turning  and ( 2 ) the cost-effectiveness of kinetic therapy . METHODS A prospect i ve , r and omized , multicenter study including 234 medical , surgical , and trauma patients ( 137 control patients , 97 patients receiving kinetic therapy ) . RESULTS Kinetic therapy significantly decreased the occurrence of ventilator-associated pneumonia and lobar atelectasis . The risk of pneumonia developing was lower ( P = .002 ) in patients receiving kinetic therapy than in the control patients . The risk of lobar atelectasis developing was decreased ( P = .02 ) for the patients receiving kinetic therapy .  Lengths of stay in the intensive care unit and in the hospital did not differ between the groups . Charges for intensive care were less in the kinetic therapy group ( 81,700 dollars ) than in the control group ( 84,958 dollars ) , but not significantly less . Twenty-one patients did not tolerate kinetic therapy and were not included in the analysis . CONCLUSION Kinetic therapy helps prevent ventilator-associated pneumonia and lobar atelectasis in critically ill patients . Costs to rent the bed may be offset by the potential cost reduction associated with kinetic therapy BACKGROUND Despite demonstrated benefits of lateral positioning , critically ill patients may require prolonged supine positioning to obtain reproducible hemodynamic measurements . OBJECTIVES TO determine the effect of 30 degree right and left lateral positions on pulmonary artery and pulmonary artery wedge pressures after cardiac surgery in critically ill adult patients . METHODS An experimental repeated- measures design was used to study 35 patients with stable hemodynamics after cardiac surgery . Subjects were r and omly assigned to 1 of 2 position sequences . Pulmonary artery and pulmonary artery wedge pressures were measured in each position . RESULTS Measurements obtained from patients in the 30 degree left lateral position differed significantly ( all Ps < .05 ) from measurements obtained from patients in the supine position for pulmonary artery systolic , end-diastolic , and mean pressures . Pulmonary artery wedge pressures did not differ significantly ; however , data were available from only 17 subjects . The largest mean difference in pressures between the 2 positions was 2.0 + /- 2.1 mm Hg for pulmonary artery systolic pressures , whereas maximum differences for end-diastolic and pulmonary artery wedge pressures were 1.4 + /- 2.7 mm Hg and 1.6 + /- 2.4 mm Hg , respectively . Clinical ly significant position-related changes in pressure occurred in 12 ( 2.1 % ) of 581 pressure pairs . Clinical ly significant changes occurred in end-diastolic pressure in 2 subjects and in pulmonary artery wedge pressure in 1 subject . CONCLUSIONS In patients with stable hemodynamics during the first 12 to 24 hours after cardiac surgery , measurements of pulmonary artery and pulmonary artery wedge pressures obtained in the 30 degree lateral and supine positions are clinical ly interchangeable BACKGROUND Critically ill patients with a low ejection fraction may be vulnerable to decreased mixed venous oxygen saturation ( SvO2 ) result ing from position change . OBJECTIVES The objectives of this study were to describe the effects of changes in positioning on SvO2 in critically ill patients with a low ejection fraction ( < or = 30 % ) and to describe the contribution of variables of oxygen delivery ( DO2 ) and oxygen consumption ( VO2 ) to the variance in SvO2 . METHOD An experimental two-group repeated- measures design was used to study 42 critically ill patients with an ejection fraction of less than or equal to 30 % ( M= 19.5 % ) . Patients were assigned r and omly to one of two position sequences : supine , right lateral , left lateral ; or supine , left lateral , right lateral . Data on SvO2 were collected at baseline , each minute after position change for 5 minutes , and at 15 and 25 minutes . RESULTS Repeated- measures multivariate analysis of variance showed a difference in SvO2 among the three positions across time ( p < .0001 ) , with the greatest differences occurring within the first 4 minutes and in the left lateral position . Stepwise multiple regression showed that VO2 accounted for a greater proportion of the variance in SvO2 with position change than did DO2 ( 54 % [ p = .001 ] vs. 31 % [ p= .001 ] ) . CONCLUSIONS Changes in SVO2 occur with positioning in critically ill patients with a low ejection fraction . These changes are transient and are the result of changes in VO2 rather than changes in DO2 BACKGROUND Investigators have suggested that lateral position may have clinical ly significant effects on oxygenation in cardiac surgery patients . Presence of lung disease and type of cardiac surgery may be important considerations . OBJECTIVES To determine the effect of position ( left , right , supine ) on blood gases in patients who have had coronary artery bypass or cardiac valvular surgery and to compare the effect of position on blood gases in cardiac surgery patients having preoperatively diagnosed lung disease with those having no lung disease . METHODS A repeated measures design was used to study 120 mechanically ventilated , postoperative cardiac surgery patients . Subjects were r and omly assigned a sequence of three positions ( supine , and 45 ; right and left lateral ) after cardiac surgery .  Heart rate , respiratory rate , and arterial blood gas values were collected in each position . Venous blood gas values were collected from a subset of 40 subjects . RESULTS A statistically significant effect of position on PaO2 was found in the group as a whole . The mean PaO2 in the left lateral position was lower than the value 
    Output:
    
Research gaps include the effectiveness of lateral positioning compared with semi recumbent positioning for mechanically ventilated patients , lateral positioning compared with prone positioning for acute respiratory distress syndrome ( ARDS ) and less frequent changes in body position .