PC1044: Rapid Bicarbonate Bolus Post Extensive Neonatal Resuscitation Leads to Increased Perfusion to the Heart and Brain

Background: Sodium bicarbonate (NaHCO3 ) is not routinely recommended in neonates with metabolic acidosis. However, post-resuscitation and in infants with perinatal metabolic acidosis and hypoxic-ischemic encephalopathy (HIE), NaHCO3 continues to be used to correct acidosis. Rapid infusion of NaHCO3 can lead to carbon dioxide (CO2 ) formation, myocardial injury, and fluctuations of cerebral blood flow. The acute effects of rapid infusion of NaHCO3 on cerebral and coronary perfusion especially post extensive neonatal resuscitation remains unknown.

Methods: Twelve near-term lambs (138-140d) at 1-hour post-resuscitation for severe asphyxia were given 2meq/kg bicarb followed by 2ml flush via a central line. Blood gas parameters (pH), arterial carbon dioxide (PaCO2 ), arterial oxygenation (PaO2 ), base excess (BE), coronary blood flow (ml/kg/min), carotid blood flow (ml/kg/min) were recorded 15 minutes before and after administration of NaHCO3. We further delineated the lambs who received NaHCO to pH < 7.1 and pH ≥ 7.1. The effect of NaHCO3 with arterial carbon dioxide of < 35mmHg and >35mmHg was also analyzed.

Results: Eight lambs had a pH < 7.1 and four had a pH ≥ 7.1 before administering NaHCO (Figure 1A). The gas exchange based on pH before and after NaHCO3 is represented in Figure 1B. There was a significant rise in exhaled CO levels (fig 1C) after NaHCO3 administration in all lambs and a significant change in PaCO3 in lambs with pH ≥7.1. Coronary and carotid blood flows after NaHCO3 (Figure 1C) administration were significantly higher. When comparing the impact of NaHCO3 in animals with PaCO2 < 35 or >35mmHg, we found that coronary, carotid, and pulmonary flows were significantly higher when the PaCO2 was >35mmHg.

Conclusion: Following extensive resuscitation, rapid NaHCO3 administration led to a significant rise in myocardial and cerebral perfusion along with higher levels of exhaled carbon dioxide. The effect of increased flow appears to be primarily due to changes in CO2 levels. These acute changes could be detrimental, especially during the reperfusion phase of ischemic injury post neonatal resuscitation.