Motoi Kosuke, Yamakoshi Yasuhiro, Yamakoshi Takehiro, Sakai Hiroaki, Tanaka Naoto, Yamakoshi Ken-Ichi
Shizuoka Institute of Science and Technology, 2200-2 Toyosawa, Fukuroi, 437-8555, Japan.
Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo, 060-0814, Japan.
Biomed Eng Online. 2017 Jan 11;16(1):12. doi: 10.1186/s12938-016-0304-9.
Taking a bath sometimes poses a risk for subjects with chronic cardiopulmonary disorders, due to the thermal effect and water pressure on his/her body. The ECG measurement would be helpful for the early recognition of abnormal cardiac beats and respiratory conditions. This paper describes a new attempt to improve on previous bathtub ECG measurement techniques that had electrodes placed inside the bathtub that were intrusive to the subjects' bathing experience. This study is concerned with the initial development of a method to measure an electrocardiogram (ECG) through tap water without conscious awareness of the presence of electrodes that are placed outside the bathtub wall.
A configuration of capacitive coupling electrodes placed outside the bathtub was designed so that the electrodes could be hidden. The capacitive coupling was made from the electrodes to the water through the bathtub wall. Two electrodes with an active shielding amplifier covered further by an electromagnetic shield were fixed to the outside surface of the bathtub wall, near the bather's right scapula and left foot. The potential difference between these two electrodes, similar to the bipolar lead-II ECG, was amplified to obtain raw signals inclusive of ECG/QRS components. Respiration intervals were also derived from ECG/RR intervals. Comparison experiments between this bathtub method and conventional direct methods with spot-electrodes and a chest-band sensor were made using 10 healthy male volunteers (22.2 ± 0.98 years).
The ECG signal was detectable through tap water as well as water with differing conductivity resulting from mixing bathwater additives with the water. ECG signals and respiration curves derived from ECG/RR intervals were successfully obtained in all subjects. The intervals of the ECG/RR and respiration obtained by the bathtub system and by the direct method were respectively agreed well with each other.
The ECG signal, in particular ECG/QRS components, were successfully detected utilizing capacitive coupling electrodes placed outside the bathtub wall. Also, the ECG/RR and respiration intervals were determined with reasonable accuracy as compared with the conventional direct methods.
由于热水澡对身体的热效应和水压作用，洗澡有时会给患有慢性心肺疾病的患者带来风险。心电图测量有助于早期识别异常心跳和呼吸状况。本文介绍了一项新的尝试，旨在改进以往的浴缸心电图测量技术，以往技术是将电极置于浴缸内，会干扰受试者的沐浴体验。本研究关注一种通过自来水测量心电图（ECG）的方法的初步开发，该方法无需受试者有意识地感知置于浴缸壁外的电极的存在。
设计了一种置于浴缸外的电容耦合电极配置，以便隐藏电极。通过浴缸壁实现从电极到水的电容耦合。两个带有有源屏蔽放大器且进一步被电磁屏蔽覆盖的电极，固定在浴缸壁外表面，靠近沐浴者的右肩胛骨和左脚。这两个电极之间的电位差，类似于双极肢体导联II心电图，被放大以获得包含心电图/ QRS成分的原始信号。呼吸间隔也从心电图/ RR间隔中得出。使用10名健康男性志愿者（22.2 ± 0.98岁）对这种浴缸测量方法与采用点状电极和胸带传感器的传统直接方法进行了对比实验。
通过自来水以及混合了沐浴添加剂的具有不同电导率的水都能检测到心电图信号。在所有受试者中均成功获得了从心电图/ RR间隔得出的心电图信号和呼吸曲线。浴缸系统和直接方法所获得的心电图/ RR和呼吸间隔分别彼此吻合良好。
利用置于浴缸壁外的电容耦合电极成功检测到了心电图信号，特别是心电图/ QRS成分。此外，与传统直接方法相比，心电图/ RR和呼吸间隔的测定具有合理的准确性。
