Heart rate variability as a predictor of infection and organ dysfunction in neurological patients

Background: Bacterial infection is a major cause of morbidity and mortality in patients admitted to Intensive Care Unit (ICU). Early diagnosis and timely, appropriate treatment can save the lives of many patients with severe infection. Analysis of activity of the autonomic nervous system (ANS) may provide a novel approach in early detection of developing infections. Heart rate variability (HRV) analysis has shown that the degree of alteration of frequency profiles correlates with illness severity. We intended to use HRV and measurement of autonomic function changes as a tool to observe and predict the incidence of infection and organ dysfunction in neurologically ill patients admitted to the ICU. Methodology: Adult patients admitted to the ICU in our hospital were included in this prospective observational study. They were monitored for HRV changes using the portable ANSiscope device. For analysis, the patients were divided into two groups depending on the severity of autonomic dysfunction – ≤40% and >40%. Infection was defined using the ‘CDC/NHSN Surveillance Definitions for Specific Types of Infections’. Results: 47 (72%) of the 65 patients studied developed infection in the ICU. Most of them developed single system infection (53%), lower respiratory infection the most common. The two groups did not differ with respect to Glasgow coma scale, mean percentage of autonomic dysfunction, median level of sympathetic dysfunction and percentage of individuals with mean autonomic dysfunction >40%. There was a significant association between sympathetic dysfunction and the percentage of autonomic dysfunction. A high number of patients were found to have higher percentage of sympathetic dysfunction with reduced HRV. Conclusion: Patients with neurological diseases have autonomic dysfunction secondary to their disease process itself. There is no conclusive evidence that changes in HRV characteristics can precisely predict infection or organ dysfunction. The use of changes in HRV alone may not help in early prediction of infection and organ dysfunction.

No conflict of interest has been declared by the author(s).