Alterations in Cardiac Function During Hemodynamic Fluctuations in Major Neurosurgery: An Evaluation Using Transesophageal Echocardiography.

Introduction: Maintaining hemodynamic stability during the perioperative period of major neurosurgical procedures is of paramount importance. A major challenge for anesthesiologists during hemodynamic fluctuations is identifying the underlying cause to guide appropriate therapy. Limited literature is available on the utility of transesophageal echocardiography (TEE) during hemodynamic fluctuations in major neurosurgery. We prospectively investigated the role of TEE-derived measures of preload, myocardial contractility, and afterload to evaluate the causes of hemodynamic instability during neurosurgery.

Methods: Sixty-three adult patients (American Society of Anesthesiologists (ASA) risk grades 1 and 2) undergoing elective neurosurgical procedures in Sree Chitra Tirunal Institute for Medical Sciences & Technology (SCTIMST), Thiruvananthapuram, India, were included. An episode of significant hemodynamic instability was defined as a change of ±20% of either heart rate or blood pressure or both from the baseline. During each episode, TEE was used to identify changes in preload, myocardial contractility, and afterload, and these data were used to ascertain the cause of hemodynamic instability. For each of the variables, i.e., heart rate (HR), systolic blood pressure (SBP), and mean arterial pressure (MAP), a chi-square test was used to assess significant changes in the TEE variables measured between those with significant changes and those without. A p-value of <0.05 was taken as statistically significant.

Results: A total of 137 episodes of significant changes in heart rate and blood pressure were observed. Bradycardia was associated with improved preload variables. Tachycardia was associated with increased stroke volume variation (SVV), superior vena cava collapsibility index (SVC-CI), increased myocardial contractility, increased cardiac output (CO), reduced stroke volume (SV), and increased systemic vascular resistance (SVR). A decrease in SBP was associated with a decrease in preload indices. An increase in SBP showed a significant increase in SVR. A decrease in MAP was associated with preserved SVC-CI, but a significant reduction in CO. An increase in MAP was associated with a significant reduction in SV and an increase in SVR.

Conclusion: By integrating TEE measures of preload, afterload, and contractility, we gain better insight into the clinical context, which enables us to respond effectively and target therapy appropriately during the perioperative period.