Validity of heart rate variability measurement by Polar® v800 heart rate monitor in critically ill patients

Background: Heart rate variability (HRV) analysis is a relevant indicator of autonomic nervous system function over the cardiovascular system. The usual way to measure this variability is from the electrocardiogram (ECG). To assess the validity of HRV measurements obtained from a heart rate monitor (HRM) Polar® V800 in critically ill adult subjects. A prospective, repeated measures, observational study was conducted in two in the Chilean intensive care units. Twenty-one different HRV variables were simultaneously assessed using a Polar® V800 HRMs and an ECG Mortara® H3 Holter device. The data was collected from the clinical record and physical examinations. The evaluations were conducted for 10 minutes at a time and simultaneously, during which the subjects had to remain supine and at rest. The sampling frequency was 1000 Hz, providing a temporal resolution of 1 millisecond for each RR period. Thirty adult subjects were included with an average age of 33.63 ± 8.91 years. When comparing both HRV assessment methods, only 3 variables showed statistically significant differences (p ≤ 0.05). As well, the correlations showed 4 strong and 17 near-perfect associations, which were positive and statistically significant (p ≤ 0.001). In addition, intraclass correlation coefficients (between 0.744 and 1) and bias determined using the Bland-Altman method found both methods to be concordant. The Polar® V800 monitor is a valid tool for assessing HRV in critically ill adult subjects.