Ha Thi Hai DuongOxford University Clinical Research Unit, Ho Chi Minh City, Vietnam; Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam; Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom;
Tetanus is a disease associated with significant morbidity and mortality. Heart rate variability (HRV) is an objective clinical marker with potential value in tetanus. This study aimed to investigate the use of wearable devices to collect HRV data and the relationship between HRV and tetanus severity. Data were collected from 110 patients admitted to the intensive care unit in a tertiary hospital in Vietnam. HRV indices were calculated from 5-minute segments of 24-hour electrocardiogram recordings collected using wearable devices. HRV was found to be inversely related to disease severity. The standard deviation of NN intervals and interquartile range of RR intervals (IRRR) were significantly associated with the presence of muscle spasms; low frequency (LF) and high frequency (HF) indices were significantly associated with severe respiratory compromise; and the standard deviation of differences between adjacent NN intervals, root mean square of successive differences between normal heartbeats, LF to HF ratio, total frequency power, and IRRR, were significantly associated with autonomic nervous system dysfunction. The findings support the potential value of HRV as a marker for tetanus severity, identifying specific indices associated with clinical severity thresholds. Data were recorded using wearable devices, demonstrating this approach in resource-limited settings where most tetanus occurs.
Financial support: This work was supported by the Wellcome Trust (grant no. 107367/Z/15/Z CLT) and VITAL (215010/Z/18/Z). J. C. was supported by travel funding from Brasenose College, University of Oxford, and the MSc in Clinical and Therapeutic Neuroscience, University of Oxford, United Kingdom. J. C. was also supported by the Rosemary Maguire Educational Bursary from Parkinson’s UK. The funding sources had no involvement in the design of the study. D. A. C. is funded by a Royal Academy of Engineering Research Chair, a National Institute of Health Research (NIHR) Research Professorship, the NIHR Oxford Biomedical Research Centre, the InnoHK Centre for Cerebro-cardiovascular Engineering, and the Pandemic Sciences Institute at Oxford University.