A Study Protocol on Assessment of Heart Rate Variability as a Prognostic Marker in Critically Ill Patients

Background: Calculation of heart rate variability (HRV) is the most popular approach of actual evaluation of autonomic nervous system (ANS) dysregulation, representing natural physiological changes. The natural changes take place in the interim among successive heart beats when sympathetic and parasympathetic expression is balanced on the heart's electrical conduction system. Numerous adult studies have shown that reductions in HRV predate clinical decline, indicate therapy response in correlation with results. Therefore, HRV can be functional as a measure of more accurate clinical perception. This study aims to determine role of heart rate variability and other risk factors as a prognostic marker for 90-day survival among patients admitted to critical care units.

Methods: This will be an Observational Cross-sectional Study with Control Group and will include hypertension, diabetes mellitus, Myocardial Infarction, Stroke, Sepsis cases and control cases. The patients admitted in Medicine critical care unit will be included in the study and they will be evaluated for HRV and APACHE IV scoring. Patients demographic profile, anthropometric measurements and history of other comorbid conditions will be documented. Patients’ outcome indicators like duration of hospital stay, 90-day survival and mortality will be obtained .Data will be analyzed by appropriate statistical tests.

Expected Results: Mixed effects models will demonstrate that the result of three HRV will be relatively lower from the start of day and night compared to the last day and night of MICU admission. The significant relationship between the variability of time from enrollment and log heart rate values is expected over the last day and night of MICU stay. Also, average HRV is expected to persist significantly higher as compared with that of the first day and night.