Long-Term Continuous Heart Rate Variability Monitoring Over 20 Days for Severe Tetanus: A Case Report

BACKGROUND Severe tetanus causes rapid fluctuations in blood pressure and pulse rate due to autonomic nervous system dysfunction. Heart rate variability (HRV), defined as subtle, periodic variation in the interval between heartbeats, is widely recognized as a noninvasive measure of autonomic nervous system function. We continuously monitored HRV in a patient with severe tetanus to better understand the underlying autonomic dysfunction. CASE REPORT A 75-year-old man with no documented history of tetanus vaccination presented to the emergency department with back and neck pain, muscle stiffness, and lockjaw after an outdoor injury to his right foot. He was intubated and placed on mechanical ventilation, then admitted to the intensive care unit for further management. Rapid fluctuations in blood pressure were observed from day 1 to day 33 of hospitalization, consistent with autonomic nervous system dysfunction. On day 37, the patient was successfully weaned off the ventilator and discharged from the intensive care unit. The frequency of consecutive HRV spikes was recorded and analyzed alongside systolic blood pressure spikes, based on electrocardiogram waveform monitoring. The analysis covered a 22-day period, from days 12 to 33 of hospitalization. HRV analysis showed that the frequency of systolic blood pressure spikes was strongly associated with changes in HRV spike frequency. CONCLUSIONS If a method for real-time HRV analysis is established, long-term continuous HRV monitoring may prove useful for diagnosing and understanding autonomic nervous system dysfunction in cases of severe tetanus.