Supplementary Material for: Association between Brain and Kidney Near-Infrared Spectroscopy and Early Postresuscitation Mortality in Asphyxiated Newborn Piglets

<p><b><i>Background:</i></b> Early outcome predictors after delivery room cardiopulmonary resuscitation (CPR) of asphyxiated newborns are needed. <b><i>Objectives:</i></b> To investigate if cerebral (rScO<sub>2</sub>) and renal (rSrO<sub>2</sub>) tissue oxygen saturation 30 min after return of spontaneous circulation (ROSC) are different between surviving versus nonsurviving piglets with asphyxia-induced cardiac arrest and CPR. Further, to investigate the relationship of rScO<sub>2</sub> and rSrO<sub>2</sub> to cardiac output (CO), blood pressure (BP), and biochemical variables 30 min and 4 h after ROSC. <b><i>Methods:</i></b> Anesthetized, mechanically ventilated piglets (1-3 days, 1.7-2.4 kg) were used. rScO<sub>2</sub>, rSrO<sub>2</sub>, SpO<sub>2</sub>, right common carotid artery flow, and arterial BP were measured continuously. CO was measured with echocardiography. The piglets were asphyxiated until cardiac arrest and resuscitated. Piglets that survived 4 h after ROSC (<i>n</i> = 12) were compared with piglets that died before planned euthanasia at 4 h (<i>n</i> = 13). Left ventricular, and kidney and brain tissue lactate were analyzed. Correlations between variables were assessed. <b><i>Results:</i></b> Thirty minutes after ROSC, median rSrO<sub>2</sub> (43% [<i>n</i> = 10] vs. 25% [<i>n</i> = 2], <i>p</i> = 0.003) but not rScO<sub>2</sub> (46% [41-55] [<i>n</i> = 10] vs. 40% [22-45] [<i>n</i> = 5], <i>p</i> = 0.08) was higher in survivors than in nonsurvivors. Arterial lactate was negatively correlated and pH positively correlated with rScO<sub>2</sub> and rSrO<sub>2</sub>. Left ventricular, but not kidney or brain lactate was negatively correlated with rScO<sub>2</sub> and rSrO<sub>2</sub>. There was no correlation between CO or BP and rScO<sub>2</sub> or rSrO<sub>2</sub>. <b><i>Conclusions:</i></b> Despite satisfactory CO and BP vital organ oxygenation can be poor. Tissue oxygen saturation, pH, and lactate, as measures of anaerobic metabolism, may reflect vital organ oxygenation and outcome.</p>