Effect of spontaneous saliva swallowing on short‐term heart rate variability (HRV) and reliability of HRV analysis

Abstract

The effects of effortful swallowing and solid meal ingestions on heart rate variability (HRV) have been examined previously. The effects of spontaneous saliva swallowing on short-term HRV and reliability of HRV analysis have not been studied before. The effect of saliva swallowing on HRV analyses parameters [meanRRI, SDNN (standard deviation of normal-to-normal), LF (low frequency), HF (high frequency) powers, LH/HF] and the reliability of LF and HF powers were investigated by frequency, time-frequency and intraclass correlation coefficient (ICC) analyses. Electrocardiogram and swallowing signal that obtained from an electronic stethoscope placed on the necks of subjects were recorded simultaneously from 30 healthy and young volunteers in sitting position during 15 min. Spontaneous swallowing has been shown to significantly alter some HRV parameters (SDNN, LF power and LF/HF ratio). Time-frequency analysis results showed that the contribution of saliva swallowing to LF (1-58%) and HF (2-42%) powers could change significantly depending on the number of swallowing. The ICC of the LF and HF powers for the successive 5-min signal segments were found 0·89, 0·92, respectively. These values decreased to 0·73 and 0·90 in the subjects with more swallowing rate. When the analyses were made for 2-min signal periods, these values decreased to 0·63 and 0·67. We concluded that spontaneous saliva swallowing can change HRV parameters. We have also seen that changes in swallowing rate and use of short signal segments may reduce the reliability of HRV analyses.

Unstimulated Salivary Secretion and Heart Rate Variability in Healthy Subjects

“…13 In another study, it was reported that the action of swallowing saliva was capable of modifying the HRV. 14 On the other hand, it has been reported that people with Sjögren's syndrome present a parasympathetic/sympathetic dysfunction, which agrees with a decrease in parasympathetic activity. 15,16 On the other hand, the RMSSD and pNN50 timedomain indices of the HRV are directly related to the parasympathetic activity rate of the ANS.…”

Standard Heart Rate Variability Parameters—Their Within-Session Stability, Reliability, and Sample Size Required to Detect the Minimal Clinically Important Effect

“…We found only four studies of the within-session reliability of HRV in short-term recordings in healthy adults [13][14][15][16]. These studies showed substantial relative reliability of HRV parameters [13][14][15][16], and low absolute reliability of HRV parameters [13,15,16]. The time domain parameters of HRV demonstrated greater reliability than the frequency domain parameters of HRV [13,15,16].…”

“…The literature search revealed that reports of the stability and reliability of HRV parameters over days/weeks/months far outweigh reports of the stability and reliability of HRV parameters obtained within a single resting session. We found only four studies of the within-session reliability of HRV in short-term recordings in healthy adults [13][14][15][16]. These studies showed substantial relative reliability of HRV parameters [13][14][15][16], and low absolute reliability of HRV parameters [13,15,16].…”

“…The time domain parameters of HRV demonstrated greater reliability than the frequency domain parameters of HRV [13,15,16]. In these studies, HRV was analyzed from nonstandard 3 and 10 min segments of recordings [13,16], only one or two HRV parameters were evaluated [14,15], and notably, the sample size required to detect the minimal clinically important effect of an intervention on HRV was not estimated.…”

Effects of effortful swallowing on cardiac autonomic control in individuals with neurogenic dysphagia: a prospective observational analytical study

“…Of late, a study assessed cardiac autonomic regulation via heart rate (HR) variability (HRV) in healthy subjects throughout spontaneous swallowing 11 . The researchers revealed sudden distinct losses in the inter beat intervals (RR intervals) during the spontaneous swallowing stages.…”