.jpg "Michael Spaeder, MD, MS, FCCM photo")
Michael Spaeder, MD, MS, FCCM
Associate Professor/Fellow Director
University of Virginia School of Medicine
Charlottesville, VA
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Title: Threshold Monitoring of Cerebral Regional Oxygen Saturation in Neonates Following Cardiac Surgery
Introduction: Near infrared spectroscopy is routinely used in the noninvasive monitoring of cerebral regional oxygen saturation (crSO2) in neonates following surgery for congenital heart disease. Monitoring of crSO2 can provide clinicians with insights into oxygen delivery and consumption in neonates following cardiac surgery though clear targets or thresholds of crSO2 have yet to be established. We sought to evaluate the association between crSO2 and ventilator free days (VFDs) at a variety of thresholds in a cohort of neonates following cardiac surgery.
Methods: We prospectively captured postoperative crSO2 values in consecutive neonates (< 30 d old) that underwent cardiac surgery with cardiopulmonary bypass over a 42-month period from October 2017 to March 2021. Values of crSO2were continuously captured using the INVOS oximeter (Medtronic, Minneapolis, MN) over the first 48 hours following surgery and averaged over 1-minute intervals. Desaturation indices were established at four crSO2 thresholds (65%, 60%, 55%, 50%) and defined as the duration of time over the first 48 hours following surgery where the crSO2 was below the threshold. The primary outcome of interest was VFDs to postoperative day 28, with patients who died before day 28 assigned zero. Delayed chest closure, extracorporeal membrane oxygenation (ECMO) and single ventricle (SV) repair were considered a priori confounders.
Results: There were 160 neonates included in the study. The median age at the time of surgery was 8 days (interquartile range, 5–11 d), and there were 6 case fatalities (4%). 55 neonates (34%) underwent SV repair, 44 neonates (28%) had delayed chest closure, and 7 (4%) underwent ECMO. The median VFDs was 24 days (interquartile range, 22–25 d). Adjusting for confounders, duration of crSO2 desaturation below both 55% and 50% was associated with decreased VFDs, though the 50% threshold model demonstrated a better adjusted R-squared and was deemed superior. Every 194 minutes with crSO2 values below 50% (or 125 minutes for patients with SV repair) during the first 48 hours following surgery equated to one less VFD.
Conclusions: In neonates following cardiac surgery with cardiopulmonary bypass, an increased duration of crSO2desaturation below 50% in the early postoperative period was associated with a decrease in VFDs.