***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 .The aim of this study was to compare the ability of NIRS and pulse oximetry to detect changes in cerebral oxygenation occurring inresponse to a pause in nasal airflow ( PNA ) . Methods .Twenty-onerecordings of cerebral oxygenation index by NIRS together with oxyhemoglobinsaturation by pulse oximetry were measured on 17 preterm infants with ahistory of apnoea .  Photoplethysmography was used to confirm the accuracy ofthe pulse oximetry data . PNA events were defined as pauses of greater than 4seconds in a thermistor trace measuring nasal air flow . Results .Baseline variability in oxygenation index ( Hbdiff ) was found to be from−0.12 to + 0.13 µmol 100 g brain−1 . A fall in Hbdiff orSpO2 was defined as a decrease of greater magnitude than 2 st and arddeviations from the baseline , i.e. , −0.12 µmol 100 gbrain−1 and 3 % respectively . In 68 % of 468 PNA events a fall inoxyhemoglobin saturation ( SpO2 ) was detected and in 56 % a fall inHbdiff was detected . In 20 % of events there was no fall in cerebraloxygenation despite a fall in SpO2 . In 8 % of PNA episodes werecorded a fall in cerebral oxygenation but no fall in SpO2 . Whena fall in cerebral oxygenation was recorded , the fall was greater when theevent was also associated with a fall in SpO2 ( median(interquartile range ( IQR ) ) 0.32 ( 0.21–0.69 ) vs. 0.25 (0.16–0.43)µmol 100 g brain−1 , p < 0.05 ) . When all the PNAepisodes were review ed no close correlation was shown between the magnitudeof change in cerebral oxygenation and the change in SpO2 for smallchanges in both indices . However , large falls ( > 1.5 µmol 100 gbrain−1 ) in cerebral oxygenation were closely associated with largechanges in SpO2 . Conclusions .We conclude that bothtechniques are sensitive to changes in oxygenation during PNA . Small changesin cerebral Hbdiff and arterial SpO2 do not always correlate forphysiological reasons . A change in Hbdiff of > 0.3 µmol 100 gbrain−1 is likely to be physiologically significant and isassociated with a change in SpO2 of 12 % This study was performed to determine whether the use of continuous tcPO2 monitoring could reduce the incidence of ROP in preterm infants receiving oxygen therapy . Two hundred and ninety-six infants with birth weights less than or equal to 1300 grams were r and omly assigned to a continuous monitoring ( CM ) or a st and ard care ( SC ) group . CM infants had tcPO2 monitored continuously as long as they required supplemental oxygen while SC infants had tcPO2 monitored only during the more acute state of their illness . Management of both groups was otherwise identical . One hundred and one of 148 infants in the CM and 113 of 148 patients in the SC groups survived . Mean birth weights and gestational age were similar in both groups . Duration of mechanical ventilation and oxygen therapy was also similar . The overall incidence of ROP was 51 % in the CM and 59 % in the SC group . As birth weight for infants greater than or equal to 1000 grams increased a higher risk for developing ROP was noted in the SC group . Four infants in the CM and 5 in the SC group developed cicatricial ROP . These results suggest that continuous tcPO2 monitoring may reduce the incidence of ROP in infants with birth weights greater than 1000 grams , but not in the smaller infants in whom this complication occurs more frequently and is more severe A previous report has shown no difference between the clinical outcome of infants exposed to a high oxygen ( O2 ) regimen and those exposed to a low O2 regimen for the treatment of respiratory distress syndrome ( RDS ) .  Mechanical ventilation was not used in either group . In the present study , pulmonary function tests were performed on 14 survivors receiving the low O2 regimen ( low O2 group ) and on nine receiving the high O2 regimen ( high O2 group ) ten years after their initial illness . Similar evidence of abnormalities of large airways was found in both groups of prematurely born children that was comparable with that previously reported for normal prematurely born children . There was evidence in the high O2 group similar to that reported for ventilated survivors with RDS exposed to a high concentration of O2 . From these data , it was concluded that neonatal exposure to high O2 concentrations in the absence of mechanical ventilation is capable of causing long-term change in small airways Oxygen saturation determined by pulse oximetry was monitored in 152 pediatric surgical patients divided into two groups . In one group , the oximeter data and alarms were available ( N = 76 ) to the anesthesia team , and , in the other group , these data were unavailable ( N = 76 ) . A trained observer recorded all intraoperative hypoxic episodes and informed the anesthesia team of all major events ( i.e. , oxygen saturation less than or equal to 85 % for greater than or equal to 30 s ) ( PaO2 approximately 52 mmHg ) . Thirty-five major events occurred : 24 in the unavailable group , and 11 in the available group ( P = 0.021 ) . A greater number of major events occurred in children less than or equal to 2 yr of age ( P = 0.013 ) . Hypoxic events diagnosed by the oximeter , but not by the anesthesiologist , were more frequent in the unavailable group ( 13 ) than in the available group ( 5 ) ( P = 0.0495 ) . ASA Physical Status 3 and 4 patients were more likely to suffer a major event ( P = 0.009 available , 0.006 unavailable ) . The pulse oximeter diagnosed hypoxemia before the signs and symptoms of hypoxemia were apparent ( i.e. , prior to observed cyanosis or bradycardia ) . Major hypoxic events were unrelated to duration of anesthesia . Major events were evenly distributed among induction , maintenance , and awakening from anesthesia ; a greater number of hypoxic events occurred during induction in the unavailable group ( P = 0.031 ) . No morbidity was documented in any patient who suffered an hypoxic event . ( ABSTRACT TRUNCATED AT 250 WORDS The relation between PaO2 and retrolental fibroplasia ( RLF ) was studied prospect ively in 719 premature infants born in or treated in the intensive care units of a group of university hospitals .  Blood gas studies  were performed on 589 of these infants , 66 of whom had a diagnosis of RLF ; in 27 of these 66 , some grade of mostly nonblinding cicatricial disease developed . The frequency of RLF was highest among infants of lowest birth weight . A multivariate statistical method was used to analyze simultaneously the effect of possible etiologic factors associated with RLF . The occurrence of RLF was found to be unrelated to PaO2 , as determined by the limited information available from intermittent sampling . RLF is associated with concentration of oxygen administered in the lightest birth weight group , but the strongest association , aside from birth weight , was with time in oxygen . None of the other variables involving blood chemical values appeared to be associated with RLF . The severity of cicatricial RLF is clearly greater in infants weighing less than 1,200 g at birth . Conservative administration of oxygen may have been responsible for failure to demonstrate quantitative association between PaO2 levels and disease . Agreement between the observed and predicted numbers of infants with RLF demonstrate the strength of the multivariate technique employed in making the statistical analyses To determine whether the use of continuous transcutaneous oxygen monitoring ( tcPO2 ) could reduce the incidence of retinopathy of prematurity ( ROP ) in pre-term infants receiving oxygen therapy , a r and omized , prospect i ve trial of constant monitoring using the transcutaneous oxygen monitor versus intermittent monitoring of oxygen was performed on a population of premature infants at very high risk for the development of ROP . Two hundred ninety-six infants were r and omly assigned to either a constantly monitored ( CM ) or st and ard care ( SC ) group . CM infants had  tcPO2  monitored continuously as long as they required supplemental oxygen , whereas SC infants had  tcPO2  monitored only during the more acute state of their illness . Management of both groups was otherwise identical . One hundred one of 148 infants in the CM group and 113 of 148 in the SC group survived . The overall incidence of ROP was 51 % in the CM group and 59 % in the SC group ( no significant difference ) . In infants over 1000 g birthweight , as the weight increased there was increasing risk of developing ROP in the SC group . The odds ratio for the ROPsc : ROPcm reached 7.6 in infants between 1200 and 1300 g in infants with Apgar scores greater than or equal to 8 at 5 minutes . The incidence of cicatricial ROP was similar in both groups : four in the CM and five in the SC group 
    Output:
    
However , this study did show increased rates of chronic lung disease and home oxygen use .
AUTHORS ' CONCLUSIONS The results of this systematic review confirm that ( the now historical ) policy of unrestricted , unmonitored oxygen therapy has potential harms without clear benefits .