Changes in Blood Pressure with Different Postures While Swallowing
To investigate whether there are changes in blood pressure (BP) and pulse transit time (PTT), the swallowing experiment was conducted on six healthy young volunteers at different postures, with simultaneous recordings of BP by an automatic oscillometric device on the left arm. At the same time, the electrocardiogram (ECG) and photoplethysmgraphy (PPG) were collected to calculate PTT. The results showed that both the systolic BP (SBP) and diastolic BP (DBP) in sitting were significantly higher than those of supine at rest and after swallowing, especially the DBP. However, no obvious changes were observed on BP after swallowing at both postures. Whereas PTT decreased significantly after swallowing compared with that of rest state at supine and sitting, with no significant changes transiting from supine posture to sitting. This study confirmed that posture changes have influence on BP, with little changes caused by single swallowing, but PTT changes significantly after swallowing. This indicates that the external stress, such as swallowing, may be taken as a way for calibration for the unobtrusive BP measurement based on PTT.
KeywordsBlood pressure pulse transit time swallowing supine sitting
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