***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: Pulse oximetry was used to measure transcutaneous arterial oxygen saturation in infants aged 2 to 11 months prone and supine in quiet sleep . Groups of healthy infants ( n = 34 ) , infants with upper respiratory tract infections ( n = 13 ) , and infants with generalised moderately severe lower respiratory tract infections ( n = 17 ) were studied . No clinical ly important differences were demonstrated in any of these groups , although there was a small advantage in the prone position in the group with lower respiratory tract infection . The effect of posture on infants with more severe lower respiratory tract infection and during active sleep has yet to be determined OBJECTIVE To compare the effects of supine and prone positions on oxygen saturation ( SpO(2 ) ) , desaturation episodes ( SpO(2 ) < 90 % and > or= 20 seconds ) , and motor activity in ventilated preterm infants during their first postnatal week . DESIGN With use of a crossover design , we r and omly assigned infants to a supine/prone or prone/supine position sequence . Infants were placed in each position for 2 hours . A stabilization period of 10 minutes before observation of each position was allowed . During the protocol , care procedures were kept minimal and ventilator setting s remained unchanged . SETTING Neonatal intensive care units at 2 tertiary care centers in Taiwan . SAMPLE The sample consisted of 28 infants receiving mechanical ventilation who were 25 to 36 weeks ' gestation , without known congenital abnormalities , within 7 postnatal days of birth , and were not receiving sedation . RESULTS When prone , infants had higher SpO(2 ) , fewer episodes of oxygen desaturation , and less motor activity than when supine . No significant differences in duration of SpO(2 ) less than 90 % , 85 % , and 80 % were found between the 2 positions . Seventy-four percent of desaturation episodes were associated with vigorous motor activity and crying . CONCLUSION The prone position results in less motor activity and may stabilize oxygenation for ventilated preterm infants . This may conserve energy and decrease complications of hypoxia for sick preterm infants Respiration , as judged by gas exchange and pulmonary function , is improved in preterm infants kept in the prone rather than the supine position . The influence of position on the breathing pattern as documented by the pneumogram was studied in 14 stable preterm infants with recent clinical apnoea . Ten of the infants had  oximetry and  nasal flow studies  simultaneously with the impedance pneumogram . Each infant had consecutive nocturnal pneumograms , one in the prone , one in the supine position . The infants were kept for more than six hours in the assigned position . A significant increase in apnoea density and in periodic breathing was found in the supine v the prone position ( mean ( SE ) 4.5 (0.7)% v 2.5 (0.5)% , and 13.6 (3.2)% v 7.7 (2.2)% , respectively ) . There was no positional difference in the incidence of bradycardia and prolonged apnoea . The examination of obstructive apnoea , mixed apnoea , and cyanotic spells did not reveal a consistent disparity between the two positions . These findings indicate an increase in central apnoea in preterm infants kept predominantly in the supine position . Possible relations of positional changes to lung mechanics are discussed . When evaluating pneumograms , attention must be given to the position in which they were performed Fourteen intubated infants recovering from neonatal respiratory disease had arterial blood gases and lung mechanics measured in the supine position and in two variants of the prone position . Prone positioning result ed in significant increases in mean ( + /- SEM ) arterial oxygen tension ( Pa(o2 70.4 + /- 2.5 to 81.1 + /- 4.4 mm Hg ) , dynamic lung compliance ( 1.7 + /- 0.24 to 2.55 + /- 0.37 ml/cm H2O ) , and tidal volume ( 8.6 + /- 1.0 to 10.5 + /- 1.2 ml ) when all prone values were compared to supine values . Prone positioning with the abdomen protruding freely , when compared to all supine values , was associated with significantly increased dynamic lung compliance and tidal volume . Values for prone-abdomen free were not significantly different from values for prone-abdomen restricted . This suggests that there are clinical benefits from prone positioning in neonates recovering from respiratory disease The objective of this study was to determine the effects of body position ( supine vs prone ) on cardiorespiratory activity during quiet and active sleep in growing low birth weight ( LBW ) infants . The effect of postconceptional age on cardiorespiratory activity in the two positions was also evaluated . Fifty-one healthy , growing , appropriate for gestational age LBW infants ( 795 - 1600 g ) , ranging from 26 - 37 weeks in gestational age , were evaluated . All subjects were enrolled in an ongoing study of the effects of quality of dietary energy on the rate and composition of weight gain . Infants were r and omly assigned to the supine or prone position for the first 3 h of the 6-h studies ; the position was reversed for the second 3 h. Continuous recordings of cardiorespiratory activity were performed along with simultaneous minute by minute assignment of behavioral sleep state . Measurements of heart rate ( HR ) , heart period variability ( RR-SD ) , respiratory rate ( f ) , and respiratory variability ( fSD ) were made each minute . Low birth weight infants had higher HR and f and lower RR-SD and fSD in the prone position compared to the supine position , during both quiet and active sleep . With increasing postconceptional age , positional differences in HR increased during quiet sleep and differences in RR-SD increased during both sleep states . These data demonstrate systematic differences in cardiorespiratory control related to body position during sleep . We speculate that such positional differences are due to variations in autonomic control , and may , in turn , contribute to variations in susceptibility to sudden infant death syndrome OBJECTIVE : The purpose of this study was to determine the effects of prone and supine positioning on the cardiorespiratory stability of preterm infants with apnea and bradycardia . METHODS : A total of 22 preterm infants with symptomatic apnea and bradycardia ( gestational age of 26.9 ± 1.8 weeks and birth weight of 865 ± 235 gm ) were monitored for 24 hours ( in four sequential 6-hour blocks ) for apnea , bradycardia , and oxygen desaturation in alternating positions ( prone or supine ) following r and omization . Postconceptional age at the time of study was 31.9 ± 3.0 weeks . Respiratory rate , heart rate , and transcutaneous oxygen saturation were continuously monitored . All episodes of apnea ( ≥10 seconds ) , bradycardia ( < 100 beats per minute ) , and oxygen desaturation ( < 90 % ) were recorded on an event monitor . Episodes of apnea , bradycardia , and oxygen desaturation were defined as clinical ly significant if the following criteria were met : apnea , ≥15 seconds ; bradycardia , < 90 beats per minute ; and oxygen desaturation , < 80 % . All other recorded episodes were considered mild . The episodes were analyzed for statistical significance using the paired t-test . RESULTS : No significant differences ( p > 0.05 ) in the incidence of clinical ly significant apnea , bradycardia , or desaturation between supine and prone positions were seen in these preterm infants . CONCLUSION : Our results suggest that the cardiorespiratory stability of preterm infants is not significantly compromised by supine positioning To determine the influence of body position on chest wall and pulmonary function , we studied the ventilatory , pulmonary mechanics , and thoracoabdominal motion profiles in 20 preterm infants recovering from respiratory disease who were positioned in both the supine and prone position . Thoracoabdominal motion was assessed from measurements of relative rib cage and abdominal movement and the calculated phase angle ( an index of thoracoabdominal synchrony ) of the rib and abdomen Lissajous figures . The ventilatory and pulmonary function profiles were assessed from simultaneous measurements of transpulmonary pressure , airflow , and tidal volume . The infants were studied in quiet sleep , and the order of positioning was r and omized across patients . The results demonstrated no significant difference in ventilatory and pulmonary function measurements as a function of position . In contrast , there was a significant reduction ( -49 % ) in the phase angle of the Lissajous figures and an increase ( + 66 % ) in rib cage motion in prone compared with the supine position . In addition , the degree of improvement in phase angle in the prone position was correlated to the severity of asynchrony in the supine position . We speculate that the improvement in thoracoabdominal synchrony in the prone position is related to alterations of chest wall mechanics and respiratory muscle tone mediated by a posturally related shift in the area of apposition of the diaphragm to the anterior inner rib cage wall and increase in passive tension of the muscles of the rib cage . This study suggests that the mechanical advantage associated with prone positioning may confer a useful alternative breathing pattern to the preterm infant in whom elevated respiratory work loads and respiratory musculoskeletal immaturity may predispose to respiratory failure STUDY OBJECTIVE To compare the effect of the prone position ( PP ) vs supine position ( SP ) on oxygenation in children with acute respiratory failure ( ARF ) . DESIGN Prospect i ve , r and omized controlled trial . SETTING A 36-bed pediatric critical-care unit in a tertiary-care , university-based children 's hospital . PATIENTS Ten children ( mean [ SD ] age , 5 + /- 3.6 years ) with ARF with a baseline oxygenation index ( OI ) of 22 + /- 8.5 . INTERVENTIONS Following a period of stabilization in the SP , baseline data were collected and patients were r and omized to one of two groups in a two-crossover study design : group 1 , supine/prone sequence ; group 2 , prone/supine sequence . Each position was maintained for 12 h. Lung mechanics and acute response to inhaled nitric oxide  were examined in each position . MEASUREMENTS AND MAIN RESULTS OI was significantly better in the PP compared to the SP over the 12-h period ( analysis of variance , p = 0.0016 ) . When patients were prone , a significant improvement in OI was detected ( 7.9 + /- 5.3 ; p = 0.002 ) ; this improvement occurred early ( within 2 h in 9 of 10 patients ) and was sustained over the 12-h study period . Static respiratory system compliance and resistance were not significantly affected by the position change . Inhaled nitric oxide had no effect on oxygenation in either position . Urine output increased while prone , result ing in a significantly improved fluid balance ( + 6.6 + /- 15.2 mL/kg/12 h in PP vs + 18.9 + /- 13.6 mL/kg/12 h in SP ; p = 0.041 ) . No serious adverse effects were detected in the PP . CONCLUSION In children with ARF , oxygenation is significantly superior in the PP than in the SP . This improvement occurs early , remains sustained for a 12-h period , and is independent of changes in lung mechanics CONTEXT In uncontrolled clinical studies , prone positioning appeared to be safe and to improve oxygenation in pediatric patients with acute lung injury . However , the effect of prone positioning on clinical outcomes in children is not known . OBJECTIVE To test the hypothesis that at the end of 28 days infants and children with acute lung injury treated with prone positioning would have more ventilator-free days than those treated with supine positioning . DESIGN , SETTING , AND PATIENTS Multicenter , r and omized , controlled clinical trial conducted from August 28 , 2001 , to April 23 , 2004 , of 102 pediatric patients from 7 US pediatric intensive care units aged 2 weeks to 18 years who were treated with supine vs prone positioning .  R and omization was concealed and group assignment was not blinded . INTERVENTION Patients were r and omized to either supine or prone positioning within 48 hours of meeting acute lung injury criteria , with those patients in the prone group being positioned within 4 hours of r and omization and remaining prone for 20 hours each day during the acute phase of their illness for a maximum of 7 days , after which they were positioned supine . Both groups were treated using lung protective ventilator and sedation protocol s , extubation readiness testing , and hemodynamic , nutrition , and skin care guidelines . MAIN OUTCOME MEASURE Ventilator-free days to day 28 . RESULTS The trial was stopped at the planned interim analysis on the basis of the prespecified futility stopping rule . There were no differences in the number of ventilator-free days between the 2 groups ( mean [ SD ] , 15.8 [ 8.5 ] supine vs 15.6 [ 8.6 ] prone ; mean difference , -0.2 days ; 95 % CI , -3.6 to 3.2 ; P = .91 ) . After controlling for age , Pediatric Risk of Mortality III score , direct vs indirect acute lung injury , and mode of mechanical ventilation at enrollment , the adjusted difference in ventilator-free days was 0.3 days ( 95 % CI , -3.0 to 3.5 ; P = .87 ) . There were no differences in the secondary end points , including proportion alive and ventilator-free on day 
    Output:
    
Prone positioning was significantly more beneficial than supine positioning in terms of oxygen saturation , partial pressure of arterial oxygen , oxygenation index , thoraco-abdominal synchrony , and episodes of desaturation .
There were no statistically significant differences between any other positions .
The prone position was significantly superior to the supine position in terms of oxygenation .
However , as most patients included in the meta- analysis were ventilated , preterm infants the benefits of prone positioning may be most relevant to these infants .