Continuous and noninvasive recording of cardiovascular parameters with the Finapres finger cuff enhances undergraduate student understanding of physiology

International educators' attitudes, experiences, and recommendations after an abrupt transition to remote physiology laboratories

The COVID-19 pandemic triggered university lockdowns, forcing physiology educators to rapidly pivot laboratories into a remote delivery format. This study documents the experiences of an international group of 10 physiology educators surrounding this transition. They wrote reflective narratives, framed by guiding questions, to answer the research question: "What were the changes to physiology laboratories in response to the COVID-19 pandemic?" These narratives probed educators' attitudes toward virtual laboratories before, during, and after the transition to remote delivery. Thematic analysis of the reflections found that before COVID-19 only a few respondents had utilized virtual laboratories and most felt that virtual laboratories could not replace the in-person laboratory experience. In response to university lockdowns, most respondents transitioned from traditional labs to remote formats within a week or less. The most common remote delivery formats were commercially available online physiology laboratories, homemade videos, and sample experimental data. The main challenges associated with the rapid remote transition included workload and expertise constraints, disparities in online access and workspaces, issues with academic integrity, educator and student stress, changes in learning outcomes, and reduced engagement. However, the experience generated opportunities including exploration of unfamiliar technologies, new collaborations, and revisiting the physiology laboratory curriculum and structure. Most of the respondents reported planning on retaining some aspects of the remote laboratories postpandemic, particularly with a blended model of remote and on-campus laboratories. This study concludes with recommendations for physiology educators as to how they can successfully develop and deliver remote laboratories.

The impact of deep breathing and alternate nostril breathing on heart rate variability: a human physiology laboratory

An increase in the beat-to-beat variability of heart rate (HRV) is a robust marker of enhanced parasympathetic activity and of a calm and relaxed state. The purpose of this laboratory activity was to introduce the concept of HRV to our students, while having them address a novel question of whether two yogic breathing techniques, namely alternate nostril breathing (ANB) and standard deep breathing (DB), impact the SD of instantaneous heart rate (SDHR), a measure of HRV. Fifty-five undergraduates enrolled in a physiology course designed for nonscience majors were tasked with analyzing HR and SDHR from electrocardiograms recorded during normal breathing, DB, and ANB. A repeated-measures ANOVA showed that HR was significantly, albeit slightly, elevated from normal (74.5 ± 13.4 beats/min; means ± SD) during DB (76.5 ± 11.2 beats/min), but not during ANB (75.7 ± 10.1 beats/min). Analysis of SDHR showed significant differences between conditions (normal: 5.5 ± 2.1, DB: 8.6 ± 3.0, ANB: 7.8 ± 2.8 beats/min). The instructors further analyzed the same data set using more robust measures of HRV (SD of sequential N-N intervals, root mean square of successive differences, and high-frequency domain of HRV) to determine whether SDHR during a 2-min epoch is a sufficient measure for HRV in the undergraduate course setting. Statistical analysis for these measures showed a near identical pattern of magnitude and significance among the groups as SDHR. Our students developed a greater appreciation for the effects of breathing patterns on HRV and HR, using the simple measure of SDHR.

Muscle metaboreflex activation via postexercise ischemia as a tool for teaching cardiovascular physiology for undergraduate students

The cardiovascular responses to exercise are mediated by several interactive neural mechanisms, including central command, arterial baroreflex, and skeletal muscle mechano- and metaboreflex. In humans, muscle metaboreflex activation can be isolated via postexercise ischemia (PEI), which increases sympathetic nerve activity and partially maintains the exercise-induced increase in arterial blood pressure. Here, we describe a practical laboratory class using PEI as a simple and useful technique to teach cardiovascular physiology. In an undergraduate exercise physiology class ( n = 47), a traditional 4-h lecture was conducted discussing the neural control mechanisms of cardiovascular regulation during exercise. Thereafter, eight students (4 men and 4 women) were selected to participate as a volunteer of a practical laboratory class. Each participant performed 90 s of isometric handgrip exercise at 40% of maximal voluntary contraction, followed by 3 min of PEI. Arterial blood pressure and heart rate were measured by digital monitors at rest and during isometric handgrip, PEI, and recovery. In addition, blood samples were collected from the tip of the exercising finger for blood lactate analyses. After the laboratory class, a survey was given to determine the perceptions of the students. The findings demonstrate that this laboratory class has proved to be highly popular with students, who self-reported a significant improvement in their understanding of several aspects of cardiovascular regulation during exercise.

Students' motivation toward laboratory work in physiology teaching

The laboratory has been given a central role in physiology education, and teachers report that it is motivating for students to undertake experimental work on live animals or measuring physiological responses on the students themselves. Since motivation is a critical variable for academic learning and achievement, then we must concern ourselves with questions that examine how students engage in laboratory work and persist at such activities. The purpose of the present study was to investigate how laboratory work influences student motivation in physiology. We administered the Lab Motivation Scale to assess our students' levels of interest, willingness to engage (effort), and confidence in understanding (self-efficacy). We also asked students about the role of laboratory work for their own learning and their experience in the physiology laboratory. Our results documented high levels of interest, effort, and self-efficacy among the students. Correlation analyses were performed on the three motivation scales and exam results, yet a significant correlation was only found between self-efficacy in laboratory work and academic performance at the final exam. However, almost all students reported that laboratory work was very important for learning difficult concepts and physiological processes (e.g., action potential), as the hands-on experiences gave a more concrete idea of the learning content and made the content easier to remember. These results have implications for classroom practice as biology students find laboratory exercises highly motivating, despite their different personal interests and subject preferences. This highlights the importance of not replacing laboratory work by other nonpractical approaches, for example, video demonstrations or computer simulations.

A Pilot Study for Evaluation of Digital Systems as an Adjunct to Sphygmomanometry for Undergraduate Teaching

Objectives: Blood pressure estimation is a key skill for medical practitioners. It is routinely taught to undergraduate medical students using an aneroid sphygmomanometer. However, the conceptual understanding in the practical remains limited. We conducted the following study to evaluate the efficacy of digital data acquisition systems as an adjunct to the sphygmomanometer to teach blood pressure.

Methods: Fifty-seven first-year medical students participated in the study. An MCQ test of 15 questions, consisting of 10 conceptual and five factual questions, was administered twice – pre- and post-demonstration of blood pressure measurement using a digital data acquisition system. In addition, qualitative feedback was also obtained.

Results: Median scores were 7 (6 - 8) and 3 (1.5 - 4) in pre-test sessions for conceptual and factual questions, respectively. Post-test scores showed a significant improvement in both categories (10 (9 - 10) and 4 (4 - 4.5), respectively, Mann-Whitney U test, p < 0.0001). Student feedback also indicated that the digital system enhanced learning and student participation.

Conclusions: Student feedback regarding the demonstrations was uniformly positive, which was also reflected in significantly improved post-test scores. We conclude that parallel demonstration on digital systems and the sphygmomanometer will enhance student engagement and understanding of blood pressure measurement.

Using stimulation of the diving reflex in humans to teach integrative physiology

During underwater submersion, the body responds by conserving O2 and prioritizing blood flow to the brain and heart. These physiological adjustments, which involve the nervous, cardiovascular, and respiratory systems, are known as the diving response and provide an ideal example of integrative physiology. The diving reflex can be stimulated in the practical laboratory setting using breath holding and facial immersion in water. Our undergraduate physiology students complete a laboratory class in which they investigate the effects of stimulating the diving reflex on cardiovascular variables, which are recorded and calculated with a Finapres finger cuff. These variables include heart rate, cardiac output, stroke volume, total peripheral resistance, and arterial pressures (mean, diastolic, and systolic). Components of the diving reflex are stimulated by 1) facial immersion in cold water (15°C), 2) breathing with a snorkel in cold water (15°C), 3) facial immersion in warm water (30°C), and 4) breath holding in air. Statistical analysis of the data generated for each of these four maneuvers allows the students to consider the factors that contribute to the diving response, such as the temperature of the water and the location of the sensory receptors that initiate the response. In addition to providing specific details about the equipment, protocols, and learning outcomes, this report describes how we assess this practical exercise and summarizes some common student misunderstandings of the essential physiological concepts underlying the diving response.

Difference in Physiological Components of VO2 Max During Incremental and Constant Exercise Protocols for the Cardiopulmonary Exercise Test

[Purpose] VO₂ is expressed as the product of cardiac output and O₂ extraction by the Fick equation. During the incremental exercise test and constant high-intensity exercise test, VO₂ results in the attainment of maximal O₂ uptake at exhaustion. However, the differences in the physiological components, cardiac output and muscle O₂ extraction, have not been fully elucidated. We tested the hypothesis that constant exercise would result in higher O₂ extraction than incremental exercise at exhaustion. [Subjects] Twenty-five subjects performed incremental exercise and constant exercise at 80% of their peak work rate. [Methods] Ventilatory, cardiovascular, and muscle oxygenation responses were measured using a gas analyzer, Finapres, and near-infrared spectroscopy, respectively. [Results] VO₂ was not significantly different between the incremental exercise and constant exercise. However, cardiac output and muscle O₂ saturation were significantly lower for the constant exercise than the incremental exercise at the end of exercise. [Conclusion] These findings indicate that if both tests produce a similar VO₂ value, the VO₂ in incremental exercise would have a higher ratio of cardiac output than constant exercise, and VO₂ in constant exercise would have a higher ratio of O₂ extraction than incremental exercise at the end of exercise.

Multiscale cross-approximate entropy analysis as a measurement of complexity between ECG R-R interval and PPG pulse amplitude series among the normal and diabetic subjects

Physiological signals often show complex fluctuation (CF) under the dual influence of temporal and spatial scales, and CF can be used to assess the health of physiologic systems in the human body. This study applied multiscale cross-approximate entropy (MC-ApEn) to quantify the complex fluctuation between R-R intervals series and photoplethysmography amplitude series. All subjects were then divided into the following two groups: healthy upper middle-aged subjects (Group 1, age range: 41-80 years, n = 27) and upper middle-aged subjects with type 2 diabetes (Group 2, age range: 41-80 years, n = 24). There are significant differences of heart rate variability, LHR, between Groups 1 and 2 (1.94 ± 1.21 versus 1.32 ± 1.00, P = 0.031). Results demonstrated differences in sum of large scale MC-ApEn (MC-ApEn(LS)) (5.32 ± 0.50 versus 4.74 ± 0.78, P = 0.003). This parameter has a good agreement with pulse-pulse interval and pulse amplitude ratio (PAR), a simplified assessment for baroreflex activity. In conclusion, this study employed the MC-ApEn method, integrating multiple temporal and spatial scales, to quantify the complex interaction between the two physical signals. The MC-ApEn(LS) parameter could accurately reflect disease process in diabetics and might be another way for assessing the autonomic nerve function.

Cuffless blood pressure estimation using only photoplethysmography based on cardiovascular parameters

This study provides cuffless blood pressure estimation. In general, blood pressure changes when the subject's condition changes, and it is important to estimate it continuously and noninvasively. In many previous studies, they used PTT (Pulse Transmission Time) for estimating. However, PTT needs both electrocardiogram and photoplethysmography to be measured. Our method needs only a finger type photoplethysmographic sensor for estimating. We use the features obtained only from photoplethysmography for estimating, instead of PTT obtained from electrocardiogram. The features used are accelerated plethysmography's waveform, Heart Rate Variability and the rate of photoplethysmography's drift. Blood pressure is modeled as the product of CO (Cardiac Output) and TPR (Total Peripheral Resistance) in general. Then, we estimated blood pressure as the product of eCO and eTPR estimated by proposed photoplethysmography's features with Stepwise multiple regression analysis. Therefore, our proposed method provides not only blood pressure, but also CO and TPR. As of result, we estimated blood pressure based on eCO and eTPR, and we obtained r = 0.71. Therefore, we could obtain the result closer to Finometer in accuracy.