OHRP and SUPPORT: lessons in balancing safety and improving the way we care for patients

Oxygen saturation target range for extremely preterm infants: a systematic review and meta-analysis

IMPORTANCE

The optimal oxygen saturation (SpO2) target for extremely preterm infants is unknown.

OBJECTIVE

To systematically review evidence evaluating the effect of restricted vs liberal oxygen exposure on morbidity and mortality in extremely preterm infants.

DATA SOURCES

MEDLINE, PubMed, CENTRAL, and CINAHL databases from their inception to March 31, 2014, and abstracts submitted to Pediatric Academic Societies from 2000 to 2014.

STUDY SELECTION

All published randomized trials evaluating the effect of restricted (SpO2, 85%-89%) vs liberal (SpO2, 91%-95%) oxygen exposure in preterm infants (<28 weeks' gestation at birth).

DATA EXTRACTION AND SYNTHESIS

All meta-analyses were performed using Review Manager 5.2. The Cochrane risk-of-bias tool was used to assess study quality. The summary of the findings and the level of confidence in the estimate of effect were assessed using GRADEpro. Treatment effect was analyzed using a random-effects model.

MAIN OUTCOMES AND MEASURES

Death before hospital discharge, death or severe disability before 24 months, death before 24 months, neurodevelopmental outcomes, hearing loss, bronchopulmonary dysplasia, necrotizing enterocolitis, and severe retinopathy of prematurity.

RESULTS

Five trials were included in the final synthesis. These studies had a similar design with a prespecified composite outcome of death/disability at 18 to 24 months corrected for prematurity; however, this outcome has not been reported for 2 of the 5 trials. There was no difference in the outcome of death/disability before 24 months (risk ratio [RR], 1.02 [95% CI, 0.92-1.14]). Mortality before 24 months was not different (RR, 1.13 [95% CI, 0.97-1.33]); however, a significant increase in mortality before hospital discharge was found in the restricted oxygen group (RR, 1.18 [95% CI, 1.03-1.36]). The rates of bronchopulmonary dysplasia, neurodevelopmental outcomes, hearing loss, and retinopathy of prematurity were similar between the 2 groups. Necrotizing enterocolitis occurred more frequently in infants on restricted oxygen (RR, 1.24 [95% CI, 1.05-1.47]). Using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria, we found that the quality of evidence for these outcomes was moderate to low.

CONCLUSIONS AND RELEVANCE

Although infants cared for with a liberal oxygen target had significantly lower mortality before hospital discharge than infants cared for with a restricted oxygen target, the quality of evidence for this estimate of effect is low. Necrotizing enterocolitis occurred less frequently in the liberal oxygen group. We found no significant differences in death or disability at 24 months, bronchopulmonary dysplasia, retinopathy of prematurity, neurodevelopmental outcomes, or hearing loss at 24 months.

Oxygen targeting in preterm infants: a physiological interpretation

Randomized controlled trials evaluating low-target oxygen saturation (SpO2:85% to 89%) vs high-target SpO2 (91% to 95%) have shown variable results regarding mortality and morbidity in extremely preterm infants. Because of the variation inherent to the accuracy of pulse oximeters, the unspecified location of probe placement, the intrinsic relationship between SpO2 and arterial oxygen saturation (SaO2) and between SaO2 and partial pressure of oxygen (PaO2) (differences in oxygen dissociation curves for fetal and adult hemoglobin), the two comparison groups could have been more similar than dissimilar. The SpO2 values were in the target range for a shorter period of time than intended due to practical and methodological constraints. So the studies did not truly compare 'target SpO2 ranges'. In spite of this overlap, some of the studies did find significant differences in mortality prior to discharge, necrotizing enterocolitis and severe retinopathy of prematurity. These differences could potentially be secondary to time spent beyond the target range (SpO2 <85 or >95%) and could be avoided with an intermediate but wider target SpO2 range (87% to 93%). In conclusion, significant uncertainty persists about the desired target range of SpO2 in extremely preterm infants. Further studies should focus on studying newer methods of assessing oxygenation and strategies to limit hypoxemia (<85% SpO2) and hyperoxemia (>95% SpO2).

Dilemmas in undertaking research in paediatric intensive care

Providing evidence-based interventions for infants and children is important in paediatric intensive care, where decision making impacts most acutely on morbidity and mortality. However, despite the major progress of medicine in the 21st century, we still lack this evidence for majority of the decisions we make. In this article, we explore and suggest possible solutions for several dilemmas faced by paediatric intensive care researchers. These include ethical dilemmas such as validity of informed consent, use of deferred consent, balancing risk versus benefit and methodological dilemmas such as how to generate high-quality evidence with low-patient volume, choice of valid outcome measures and how best to use research and researchers' networks.