297 Oxygen Variability, Adherence to Oxygen Saturation Targets and Chronic Lung Disease

Abstract

Background: High blood oxygen tensions and oxygen tension variability have been linked to morbidity in preterm infants. Oxygen saturation (SpO2) monitoring is commonly used to guide oxygen therapy but appropriate target levels remain uncertain.Aim: To determine whether SpO2 variability and/or time saturated above 94% while in supplemental oxygen are risk factors for the development of chronic lung disease (CLD) defined as the requirement for supplemental oxygen at 36 weeks.Method: 94 infants who were born at less than 29 weeks gestation and survived to 36 weeks during the period October 2002 to January 2005 at the Simpson in Edinburgh, were studied. SpO2 values were downloaded every second to a computer from the time of admission until monitoring was discontinued. For the first 2 weeks of life, SpO2 variability (Standard Deviation of SpO2), fraction of time saturated above 94% (our units upper SpO2 target) while in supplemental oxygen, mean SpO2, mean fraction of inspired oxygen, and mean time spent in oxygen were calculated for each infant. Multiple logistic regression (MLR) was used to examine the relationship between these indices (plus gestation and weight) and the requirement for supplemental oxygen at 36 weeks.Results: Seven infants were excluded because of early transfer out of the intensive care unit. Data from 87 infants was analysed. After artefact removal, saturation data was available for 84% of the total time. 49 infants were still in oxygen at 36 weeks CGA. SpO2 variability in the first week of life and fraction of time saturated above 94% while in supplemental oxygen in the first two weeks of life were independent risk factors for CLD after controlling for other factors (p= 0.028, and 0.040 respectively).Conclusions: Strategies aimed at limiting the morbidity associated with oxygen administration should consider SpO2 variability, and adherence to SpO2 targets as well as the absolute SpO2 target.