Piezoelectric Sensor for the Monitoring of Arterial Pulse Wave: Detection of Arrhythmia Occurring in PAC/PVC Patients.

Previous studies have found that the non-invasive blood pressure measurement method based on the oscillometric method is inaccurate when an arrhythmia occurs. Therefore, we propose a high-sensitivity pulse sensor that can measure the hemodynamic characteristics of the pulse wave and then estimate the blood pressure. When an arrhythmia occurs, the hemodynamics of the pulse wave are abnormal and change the morphology of the pulse wave. Our proposed sensor can measure the occurrence of ectopic beats from the radial artery, and the detection algorithm can reduce the error of blood pressure estimation caused by the distortion of ectopic beats that occurs when the pulse wave is measured. In this study, we tested patients with premature atrial contraction (PAC) or premature ventricular contraction (PVC) and analyzed the morphology of the pulse waves when the sensor detected the ectopic beats. We discuss the advantages of using the Moens-Korteweg equation to estimate the blood pressure of patients with arrhythmia, which is different from the oscillometric method. Our research provides a possible arrhythmia detection method for wearable devices and can accurately estimate blood pressure in a non-invasive way during an arrhythmia.

Assessment of a Calibration-Free Method of Cuffless Blood Pressure Measurement: A Pilot Study.

This study proposes a low-cost, high-sensitivity sensor of beat-to-beat local pulse wave velocity (PWV), to be used in a cuffless blood pressure monitor (BPM). OBJECTIVE: We design an adaptive algorithm to detect the feature of the pulse wave, making it possible for two sensors to measure the local PWV in the radial artery at a short distance. Unlike the cuffless BPM that needs to use a regression model for calibration. METHOD: We encapsulate the piezoelectric sensor material in a cavity and design an analog front-end circuit. This study used color ultrasound imaging equipment to measure radial arterial parameters, including the diameter and wall thickness, to aid the estimation of blood pressure (BP) using the Moens-Korteweg (MK) equation of hemodynamics. RESULTS: We compared the blood pressure estimated by the MK equation with the reference BP measured using an aneroid sphygmomanometer in a test group of 32 people, resulting in a mean difference of systolic BP of -0.63 mmHg, and a standard deviation of ±5.14 mmHg, a mean difference of mean arterial pressure (MAP) of 0.97 mmHg, with a standard deviation of ±3.54 mmHg, and a mean difference of diastolic BP of -1.14 mmHg, with a standard deviation of ±4.08 mmHg. This study has verified its compliance with ISO 81060-2. CONCLUSIONS: A new type of wearable continuous calibration-free BPM can replace the situation that requires the use of traditional ambulatory BPM and reduce patient discomfort. CLINICAL IMPACT: In this study can provide long-term continuous blood pressure monitoring in the hospital.

An Arterial Compliance Sensor for Cuffless Blood Pressure Estimation Based on Piezoelectric and Optical Signals.

OBJECTIVE: Blood pressure (BP) data can influence therapeutic decisions for some patients, while non-invasive devices that continuously monitor BP can provide patients with a more comprehensive BP assessment. Therefore, this study proposes a multi-sensor-based small cuffless BP monitoring device that integrates a piezoelectric sensor array and an optical sensor, which can monitor the patient's physiological signals from the radial artery. METHOD: Based on the Moens-Korteweg (MK) equation of the hemodynamic model, pulse wave velocity (PWV) can be correlated with arterial compliance and BP can be estimated. Therefore, the novel method proposed in this study involves using a piezoelectric sensor array to measure the PWV and an optical sensor to measure the photoplethysmography (PPG) intensity ratio (PIR) signal to estimate the participant's arterial parameters. The parameters measured by multiple sensors were combined to estimate BP based on the P-ß model derived from the MK equation. RESULT: We recruited 20 participants for the BP monitoring experiment to compare the performance of the BP estimation method with the regression model and the P-ß model method with arterial compliance. We then compared the estimated BP with a reference device for validation. The results are presented as the error mean ± standard deviation (SD). Based on the regression model method, systolic blood pressure (SBP) was 0.32 ± 5.94, diastolic blood pressure (DBP) was 2.17 ± 6.22, and mean arterial pressure (MAP) was 1.55 ± 5.83. The results of the P-ß model method were as follows: SBP was 0.75 ± 3.9, DBP was 1.1 ± 3.12, and MAP was 0.49 ± 2.82. CONCLUSION: According to the results of our proposed small cuffless BP monitoring device, both methods of estimating BP conform to ANSI/AAMI/ISO 81060-2:20181_5.2.4.1.2 criterion 1 and 2, and using arterial parameters to calibrate the MK equation model can improve BP estimate accuracy. In the future, our proposed device can provide patients with a convenient and comfortable BP monitoring solution. Since the device is small, it can be used in a public place without attracting other people's attention, thereby effectively improving the patient's right to privacy, and increasing their willingness to use it.

Ultrafast dynamics of quasiparticles and coherent acoustic phonons in slightly underdoped (BaK)Fe2As2.

We have utilized ultrafast optical spectroscopy to study carrier dynamics in slightly underdoped (BaK)Fe2As2 crystals without magnetic transition. The photoelastic signals due to coherent acoustic phonons have been quantitatively investigated. According to our temperature-dependent results, we found that the relaxation component of superconducting quasiparticles persisted from the superconducting state up to at least 70 K in the normal state. Our findings suggest that the pseudogaplike feature in the normal state is possibly the precursor of superconductivity. We also highlight that the pseudogap feature of K-doped BaFe2As2 is different from that of other iron-based superconductors, including Co-doped or P-doped BaFe2As2.

Improved satisfaction of preoperative patients after group video-teaching during interview at preanesthetic evaluation clinic: the experience of a medical center in Taiwan.

BACKGROUND: Anesthesiologist-directed anesthetic preoperative evaluation clinic (APEC) is used to prepare patients to receive anesthesia for surgery. Studies have shown that APEC can reduce preoperative tests, consultations, surgery delays and cancellations. APEC with video-teaching has been purposed as a medium to provide comprehensive information about the process of anesthesia but it has not been practiced in small groups of patients. It is rational to assume that video-teaching in a small group patients can provide better information to patients to understand the process of anesthesia and in turn improve their satisfaction in anesthesia practice. This study was designed to evaluate the difference of satisfaction between patients who joined in small group video-teaching at APEC and patients who paid a traditional preoperative visit in the waiting area, using questionnaire for evaluation. METHODS: Totally, 237 eligible patients were included in the study in a space of two months. Patients were divided in two groups; 145 patients joined the small group video-teaching designated as study group and 92 patients who were paid traditional preoperative visit at the waiting area served as control. All patients were requested to fill a special questionnaire after postoperative visit entrusted to two non-medical persons. RESULTS: There were significantly higher scores of satisfaction in anesthesia inclusive of waiting time for surgery in the operation room, attitude towards anesthetic staffs during postoperative visit and management of complications in patients who were offered small group video-teaching in comparison with patients of traditional preoperative visit. CONCLUSIONS: The results indicated that APEC with group video-teaching could not only make patients more satisfied with process of anesthesia in elective surgery but also reduce the expenditure of hospitalization and anesthetic manpower.

Serum S-100 beta protein during coronary artery bypass graft surgery with or without cardiopulmonary bypass.

BACKGROUND: Brain damage is a serious complication of cardiac anesthesia. The purpose of this study was to detect brain damage at different surgical stages during coronary artery bypass graft with or without cardiopulmonary bypass. METHODS: We conducted a prospective, longitudinal study to evaluate serum S-100 beta protein, an early marker of brain injury, in patients electively undergoing off-pump (n = 30) or traditional coronary artery bypass graft (n = 60). Blood was sampled immediately before anesthesia, before and after cardiopulmonary bypass, and on the day after surgery. RESULTS: Serum S-100 beta protein was lowest immediately before induction of anesthesia and significantly increased before and after cardiopulmonary bypass, then declined by the first postoperative day in both groups. Peak values were highest in the traditional group directly after coronary artery bypass graft. On the day after surgery, S-100 beta protein levels were similar between groups, but were higher than baseline within each group. Significant increase in serum S-100 beta protein was also observed even before cardiopulmonary bypass in cardiopulmonary bypass patients, or before manipulation of the heart and aorta in off-pump patients. These reflect the possibility that brain damage may occur before major manipulation (cardiopulmonary bypass or manipulating heart and aorta). Moreover, S-100 beta levels did not return to normal on the day after the operation. CONCLUSIONS: This prospective study has shown that serum S-100 beta protein was not only higher than baseline both after cardiopulmonary bypass and on the day after surgery in both groups of patients but it was also significantly increased before cardiopulmonary bypass or manipulation of the heart or aorta. These findings may have implications for anesthesiologic care during the total course of cardiac surgery.