MEASUREMENT OF BASIC HEMODYNAMICS DURING MULTIPOST TRANSCUTANEOUS EXTERNAL EAR STIMULATION: A TWO-CASE STUDY

Abstract

The objectives of the investigation were to assess the short-term responses of the cardio-vascular system on the multipost transcutaneous stimulation (tANS) of the external ear (EE). The scope was to measure the forefinger photopleths (FPPG), toe photopleths (TPPG), aortic phonocardiogram (APCG), mitral phonocardiogram (MPCG) and brachial arterial blood pressure (BABP), assuming that they could be altered with the tANS. For the tANS, stimulator, two silicone ear plugs with four platinum electrodes each, and a large common electrode (CE), were used. Trials were carried out with two female volunteers, aged 25 years and 28 years. To capture the heart sounds, two customized electronic stethoscopes (transducers) were used. BABP was measured using a pressure transducer and blood-pressure appliance. To measure the FPPGs, a pulse oximeter and SpO2 finger clip were used. To measure the TPPGs, another pulse oximeter and customized SpO2 foot clip was used. Signals were gathered using a high-performance data-acquisition system. An offline analysis was made just before and just after the start of the tANS. To record the pulsations in the right brachial artery, the 2D ultrasound mode (B) of the ultrasound device was used before and during the tANS. Then, diagrams showing the vein cross-sectional area over time were constructed. The results show that vascular time intervals between heart sounds S1 and S2, captured as APCG and systolic peaks of the FPPG in the second volunteer, were slightly larger during the separate tANS of the left white (LW) and (RW) EE post than before the tANS. Furthermore, vascular time intervals between the heart sounds S1 and S2, captured as MPCG and systolic peaks of the TPPG in the second volunteer, were slightly smaller during the separate tANS of LW and RW EE post than before the tANS. Finally, tANS of the LW post elicited a slightly lower heart rate than the one measured when LW was not stimulated. In contrast, the tANS of the RW post elicited a slightly higher heart rate than the one measured when RW was not stimulated. It was also shown that the pattern of the vein cross-sectional area over time with tANS was different compared to both the FPPG and TPPG.