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INTRODUCTION: Bronchopulmonary dysplasia (BPD) is one of the most common morbidities related to preterm birth. Infants with moderate BPD are discharged on supplemental oxygen to maintain oxygen saturation between 90-96%, avoiding both hypoxia and hyperoxia, each with its own morbidity. Pulse oximetry (POX) is used to measure oxygenation in the blood. Near-infrared spectroscopy (NIRS) is a potential method to measure cerebral oxygenation and brain perfusion. To the best of our knowledge, there is a lack of normalized data for NIRS values in neonate infants going home with or without oxygen. We proposed that with combination of NIRS and pulse oximetry we could better identify a safe oxygen flow rate/concentration for babies with BPD. In doing so, we also sought to determine what the normative values of NIRS are in premature infants. METHODS: This was a prospective cohort study approved by the Bioethics Board, University of Saskatchewan. Infants were recruited from the NICU, Jim Pattison Children’s Hospital after obtaining written informed consent. One group (Control group, n=22) of relatively healthy preterm infants were recruited for NIRS measurements in relation to standard POX. We then compared NIRS and POX values on varying flow rates (0.03, 0.06, 0.12 L/Min) for moderate BPD infants going on home oxygen (n=10). RESULTS: Of the control infants in room air, the average POX value was 97.8% with SD ± 1.661 and SEM ± 0.006. The average time of hypoxia with POX below 90% was 3.5%, while time above 96% was 96.5%. The average NIRS value was 78.24% with SD ± 7.705 and SEM ± 0.027. The NIRS values for this group showed time at <60% was 1.4% of the time, 60%-80% was 50.75% and >80% was 47.9%. As expected, the difference of means between POX and NIRS (POX – NIRS) was 19.56% with the 95% confidence interval of 19.503 to 19.61. Cohen's correlation coefficient was 0.02 between the two variables Pulse Oximetry and Near-Infrared Spectroscopy. One-sided and two-sided p-tests values were 0.00. For the group on oxygen, at the flow rate of 0.03 lpm the average time with POX <90% was 2.35%, with 90-96% was 15.52% and with > 96% was 82.13 %. Time for this group with NIRS values <60% were 0.01%, 60%-80% were 58.5% and > 80% were 41.5%. At oxygen flow rate of 0.06 lpm, the average time with POX <90% was 1.43%, 90-96% was 6.08% and > 96% was 92.49%. Time for this group with NIRS values <60% was 0.6%, 60%-80% was 65% and > 80% was 34.4%. At oxygen flow rate of 0.12 lpm, the average time with POX <90% was 1.46%, 90-96% was 11.54% and > 96% was 87.00%. Time for this flow rate with NIRS values <60% was 0.2%, 60%-80% was 64% and > 80% was 34.8%. Individually, we did not see POX desaturation events associate with NIRS desaturations. CONCLUSION: As expected, there is an approximate difference of 19.5% between the POX and NIRS values with POX being higher that NIRS in healthy infants. Individually, we could not find any correlation between POX and NIRS values for hypoxia events. On average, we did not see a dose response correlation between oxygen flow rate and time spent in the hyperoxemic range across different flow rates by POX or cerebral NIRS. While NIRS could play an important adjunct role in the NICU for brain oxygen saturation, NIRS data cannot serve as a stand-alone monitoring tool.



OPTIMAL HOME OXYGEN FLOW RATE, Preterm Infants, Near infrared spectroscopy, Pulse oximetry



Master of Science (M.Sc.)




Health Sciences


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