174. Correlating Intraoperative Lactate with Resuscitation Markers in Open Cranial Vault Reconstruction

PURPOSE: Open cranial vault reconstructions often involve significant blood loss and adequate resuscitation is crucial. Metrics such as heart rate (HR), mean arterial pressure (MAP), and urine output (UO) are ubiquitously used but are not as sensitive as lactic acid levels in detecting cellular and tissue hypoxia. Our study evaluates how well physiologic markers of resuscitation correlate with intraoperative lactate levels-an indicator of anaerobic cellular metabolism. METHODS: A retrospective chart review was conducted of patients who underwent open cranial vault reconstruction at our institution from 2013 to 2021. Intraoperative data such as lactate levels, HR, MAP, and UO were collected. The correlation between lactate levels and other physiological markers were analyzed within 5-, 10-, and 15-minute timeframes to assess their potential as real-time indicators of cellular resuscitation. Pearson correlation, Mann-Whitney-U, Chi-square/Fisher’s exact, and multivariable logistic regression were used to assess the relationship between lactate levels and other parameters. RESULTS: 148 patients with craniosynostosis were analyzed. Median age at surgery was 1.3 years (IQR 0.8, 3.2). Majority of patients (86.5%) were non-syndromic, and 65.5% had no chronic health conditions. 17.6% experienced at least one instance of elevated intraoperative lactate. No significant correlation was found between intraoperative lactate levels and HR or MAP. However, patients with hyperlactatemia had higher weight, lower hematocrit, and decreased UO compared to those without. For each 1 kg increase in weight, the odds of hyperlactatemia increased by 38% (p=0.004). Conversely, for each 1% increase in preoperative hematocrit, the odds of hyperlactatemia decreased by 20% (p=0.016). Additionally, for each 100cc increase in urine output, the odds of hyperlactatemia decreased by 37% (p=0.008). No correlation was identified between hyperlactatemia and postoperative complications. CONCLUSION: These findings suggest that intraoperative lactate levels do not direly correlate with conventional vitals measuring hemodynamic stability, specifically HR and MAP. However, hyperlactatemia was found to have a direct inverse relationship with UO and hematocrit, two key indicators of perfusion. This relationship suggests that adequate hydration may be protective and elevating preoperative hematocrit with Epogen may avoid intraoperative hypoperfusion and transfusion. Based on these findings, we caution against strict reliance on vitals for assessment of resuscitation during open cranial vault reconstruction and recommend incorporating intraoperative lactic acid levels for a more accurate assessment of cellular and tissue perfusion