Features of Heart Rate Variability Capture Regulatory Changes During Kangaroo Care in Preterm Infants

Changes in autonomic regulation due to Kangaroo care remain unaffected by using a swaddling device

“…Consecutively, beat‐to‐beat intervals, also known as normal‐to‐normal (NN) intervals were determined . On the basis of previous research, we calculated four features of heart rate variability: the standard deviation of all NN‐intervals (SDNN), the root mean square of the successive difference between NN‐intervals (RMSSD), the percentage of NN‐intervals corresponding to transient decelerations (pDec) and the standard deviation of the NN‐intervals corresponding to transient decelerations (SDDec; ). The feature SDNN is believed to be reflective of overall variability, whereas the RMSSD reflects short‐term variability .…”

“…The feature SDNN is believed to be reflective of overall variability, whereas the RMSSD reflects short‐term variability . The features pDec and SDDec are reflective of regulatory instability and are specifically designed to capture heart rate decelerations, both transient decelerations as well as prolonged bradycardia . We calculated the mean value and the standard error of the mean (SEM) for these four features of heart rate variability every minute, using data from the previous five minutes to obtain a time series graph for each heart rate variability feature.…”

“…We calculated the mean value and the standard error of the mean (SEM) for these four features of heart rate variability every minute, using data from the previous five minutes to obtain a time series graph for each heart rate variability feature. Since for these time series we were interested in the effect of Kangaroo care and not absolute values per se , a normalisation procedure or baseline removal was carried out by subtracting the mean value of each feature in the first 30 minutes of the pre‐Kangaroo care period from the corresponding time series, as detailed in a prior publication .…”

“…For statistical analyses of heart rate variability and vital signs, representative or stable epochs were defined to enable reliable comparison of differences in absolute values on intervention days versus control days, similar to previous studies .…”

“…). A detailed discussion motivating this approach is provided in a previous publication . Briefly, the first 30 minutes of the pre‐Kangaroo care period is a stable period since it is free of routine nursing intervention.…”