Vol. 17 •Issue 9 • Page 17
Home Pathways
We’re Home — Now What?
Home oxygen therapy for newborns presents more questions than answers
For more than half a century, clinicians have been treating neonates with oxygen therapy, but despite this history, controversy remains about its use for high-risk infants at home.
Supplemental home oxygen is prescribed for neonates with many different conditions, including hypoventilation due to neuromuscular disease, congenital heart disease, and chronic lung disease.1-2Proposed benefits include improved weight gain and prevention of sudden infant death syndrome.3In addition, chronic or repetitive intermittent hypoxia can result in pulmonary vasoconstriction and ultimately pulmonary hypertension, which can be reversed by supplemental oxygen.4Pivotal trials have examined target ranges for oxygen saturations in pre-term infants, allowing clinicians to apply some of these insights to home oxygen use.5-6However, no randomized trials address the specific questions of when to prescribe supplemental home oxygen, what saturations to target, when to wean, and how home oxygen therapy influences outcomes. Furthermore, with no agreement about when oxygen is required, studies that describe oxygen dependence as an outcome are difficult to interpret.
Which saturations trigger home oxygen therapy?
This review focuses on home oxygen therapy for bronchopulmonary dysplasia or chronic lung disease. We will follow the National Institute of Child Health and Human Development’s definition of oxygen dependence at 36 weeks post-menstrual age.7-8Various recommendations for threshold saturations for prescribing home oxygen for the infant with BPD have been published.1-3 literature review conducted in 1998 recommends supplemental oxygen for saturations less than 93 percent with a therapeutic goal of saturations greater than 95 percent, since supplemental oxygen can reduce pulmonary vascular and airway resistance.3More recently, researchers attempted to standardize the use of oxygen supplementation to maintain a saturation of at least 90 percent in infants over 36 weeks corrected age.1-2Among 181 physicians at Vermont Oxford Network hospitals in 2002, the saturation threshold triggering home therapy varied from less than 84 percent to less than 96 percent.9Similar ranges (85 percent to 94 percent) were found in a national survey in Germany.10What oxygen saturation levels should we target in awake states, sleeping states, and during feeds?
The range of “normal oxygen saturations” in infants is broad.11One study demonstrated that in healthy infants less than 19 weeks old, duration of time with saturations less than 90 percent varied from 1 to 183 seconds. Minimum saturations in these healthy infants were less than 81 percent during every week of the study. This extreme variation in normal saturations makes it challenging to select saturation ranges to actively target with oxygen therapy. However, extrapolations can be made from some related randomized trial data.
The STOP-ROP and BOOST trials provide some information about supplemental oxygen use in younger, hospitalized infants.7-8In STOP-ROP, infants with pre-threshold retinopathy of prematurity were randomized to two oxygen saturation ranges: 89 percent to 94 percent (low) or 96 percent to 99 percent (high). The latter group had no decrease in progression of ROP, but they had higher rates of pneumonia and CLD exacerbations.7
The BOOST trial randomized infants born at less than 30 weeks gestation to a targeted oxygen saturation range of 91 percent to 94 percent or 95 percent to 98 percent. While there was no difference in growth and development at corrected age of 1 year, the high saturation group received an increased number of days on oxygen and had a trend toward excess deaths from pulmonary causes.8Both trials suggest that higher saturations can lead to ongoing lung damage from oxygen toxicity. Therefore, it is reasonable to target ranges between 89 percent to 95 percent while on home oxygen.
Changes in breathing rate during sleep can lead to increased desaturations, especially in the prone position.12Also, pre-term infants with BPD have more severe hypoxemia after feeding than during feeds and have weaker suck strength than term infants.13-14Therefore, infants with CLD on home oxygen therapy may require increased flow to maintain target saturations when sleeping and during or after feeding.
Does supplemental home oxygen use affect neurodevelopmental outcome?
A few studies have examined the relationship between oxygen saturations and neurodevelopmental outcomes. The BOOST trial found there were no significant differences in the proportion of infants in either group with a major developmental disability.8
However, this study only followed infants to 1 year corrected age, which may not be sufficient time to accurately assess outcomes.
Currently, there are several trials enrolling in the U.S., Canada, United Kingdom, and Australia, which will examine oxygen targets in the first weeks of life, with primary endpoints of infants’ neurodevelopmental outcomes at 2 years corrected age.15A study published in 2007 examined developmental outcomes of extremely pre-term infants by separating them into three cohorts: BPD and home oxygen, BPD and room air, and infants without BPD.16At 1 year of age, the infants without BPD scored significantly higher on developmental testing than the other two groups; however, the difference in scores between the two BPD groups was not significant.
Several other studies have shown that BPD is associated with poor long-term neurodevelopmental outcome.17-18Thus, BPD is independently associated with adverse outcome, an effect which is likely not mitigated by the administration of supplemental home oxygen.
Does supplemental oxygen help infants with BPD gain weight?
Three small, observational studies suggested that oxygen supplementation promotes weight gain for infants with CLD.19-21A 1987 study described 22 infants with BPD, in whom weight gain was inversely related to parental compliance with prescribed oxygen therapy. Of course, noncompliant caregivers may be haphazard in other aspects of care, potentially confounding the results of this study.19A 1989 study of 30 extremely low-birth-weight infants reported, without comparison to controls, that supplemental home oxygen promoted weight gain in these infants.20The third study, published in 1996, demonstrated a significantly decreased rate of weight gain in a small number of infants with BPD after discontinuation of supplemental oxygen only if the infant had prolonged saturations of 88 percent to 91 percent in sleep. However, this study was done at high altitude and is likely not generalizable to infants living close to sea level.21BOOST is the only randomized, controlled trial that has addressed the relationship between oxygen saturations and growth.8In the BOOST trial, there was no difference between the 91 percent to 94 percent saturation group and the 95 percent to 98 percent oxygen saturation group in any growth parameter at 1 year corrected age. Considering the limited available literature, little evidence supports the theory that supplemental oxygen promotes growth.
Does home oxygen supplementation prevent SIDS?
Some authors suggest that supplemental oxygen therapy can decrease the risk of SIDS and apparent life-threatening events (ALTE).3The CHIME studies evaluated both term and preterm infants receiving home monitoring.22Significant cardiorespiratory events were common in preterm infants until 43 weeks corrected age. The authors defined significant events as apnea for 30 seconds, heart rate of 60 beats per minute for 10 seconds at postconceptional age of less than 44 weeks, or heart rate of 50 beats per minutes for 10 seconds if at least 44 weeks.
They found that events previously considered to be “pathologic” are actually quite common, even in healthy, term infants. Furthermore, these events were related to neither risk of ALTE nor risk of SIDS. This observational study was not randomized and infants with home oxygen therapy were excluded. However, based on these results, it seems unlikely that oxygen therapy could reduce the risk of SIDS.
Does home oxygen use reduce cost of care?
Many sources claim that use of home oxygen can facilitate early discharge from the intensive care unit for the infant with BPD. In the BOOST trial, even though 78 percent more infants in the high saturation group were sent home on oxygen, median time from randomization to discharge was 50 days in both groups.8Some report increased rehospitalization rates, longer rehospitalizations, more outpatient visits, and more outpatient medications for infants who require supplemental home oxygen.23-24However, these are all confounded by the fact that only the sickest infants are sent home with supplemental oxygen.
On the other hand, one study grouped infants by whether they were cared for at a hospital with frequent use of home oxygen, or one that uncommonly used home oxygen.25The authors compared in- and out-of-hospital costs of care for these infants and found that length of stay was longer and cost of neonatal care was higher for those infants who were in a hospital with restricted use of home oxygen. Furthermore, the restricted home oxygen group had more community health care contacts after discharge. Cost of care after discharge was equal in the two groups.
Based on the evidence, we can conclude use of home oxygen likely permits earlier discharge from the neonatal ICU, and it does not necessarily lead to increased cost of outpatient care.
For a list of references, look under the “Magazine” tab at www.advanceweb.com/respmanager.
Sara B. DeMauro, MD, and Moira Crowley, MD, are fellows in the department of pediatrics, division of neonatology at the Children’s Hospital of Philadelphia. Haresh Kirpalani, MD, MSc, is professor in the same division.
