Heart rate variability predicts severe hypotension after spinal anesthesia.

Area of Science:

• Anesthesiology
• Autonomic Nervous System Physiology
• Cardiovascular Monitoring

Background:

• Hypotension following spinal anesthesia (SA) is a significant clinical concern.
• Vasodilatation is a primary cause of SA-induced hypotension.
• Heart rate variability (HRV) offers an indirect assessment of autonomic nervous system control.

Purpose of the Study:

• To evaluate the predictive capability of HRV for hypotension post-SA.
• To determine if the low to high frequency ratio (LF/HF) of HRV can predict significant blood pressure decrease after SA.
• To compare the predictive accuracy of LF/HF with established methods.

Main Methods:

• Retrospective analysis of HRV in 30 patients based on post-SA systolic blood pressure (SBP).
• Prospective study of 70 patients stratified by baseline LF/HF ratio into two groups.
• Assessment of sensitivity and specificity of LF/HF for predicting >20% SBP decrease.

Main Results:

• Retrospective analysis revealed LF/HF differences correlated with hypotension severity.
• Prospective analysis showed significantly lower post-SA SBP in patients with high baseline LF/HF (66% of baseline) compared to low LF/HF (91% of baseline).
• Receiver operator characteristic analysis indicated an LF/HF threshold > 2.5 achieved 85% sensitivity and specificity for predicting >20% SBP decrease.

Conclusions:

• Pre-SA HRV analysis, specifically the LF/HF ratio, can predict post-SA hypotension with high accuracy.
• The LF/HF ratio serves as a valuable tool for identifying patients susceptible to SA-induced hypotension.
• The predictive performance of LF/HF surpasses that of conventional predictors.