Money, resources and the opportunity cost of time spent in the laboratory have led to the revision of the value of laboratory training. The classic manipulation of the diving response in a teaching laboratory revolves around the relationship between heart rate, peripheral circulation and oxygen saturation. The brain, specifically the medulla of the brainstem, maintains the body's vital functions in functioning properly (Abrahams et al., 1991).
Peripheral vasoconstriction is one of the body's main reflexes used to conserve oxygen (Foster and Sheel, 2005). In order to conserve oxygen and preserve what is left for the brain, the exchange of oxygen must be slowed down in other parts of the body (Foster and Sheel, 2005). In an effort to address one of the core competencies established by the National Science Foundation (i.e., demonstrating a relationship between science and society; Wei, 2011), information about human uses for the immersion response was.
The dive response is an easy and relatively safe way to 'trick' the body into conserving more oxygen and blood flow for the heart and brain. In a laboratory setting by manipulating multiple independent variables and measuring dependent variables, students should be able to elicit a greater range of responses compared to typical recreations of the diving response experiment that manipulate only cold water immersion. After completing the diving response exercise and the post-laboratory examination, participants received a pizza as a thank you.
Post-laboratory surveys were distributed to laboratory participants after completion of the diving response exercise and student analysis (Table 2).
Results
For this experiment, air exhaled after a non-absorbed breath hold was assumed to contain a typical concentration of carbon dioxide. Exhalation after cold water immersion had the lowest concentration of carbon dioxide, while exhalation after apnea after exercise had the highest above-average concentration of carbon dioxide. Oxygen saturation in the subjects' peripheral systemic circulation was measured during each breath hold as well as during baseline testing (Fig. 4).
Pulse amplitude varied with each apnea, from a mean of 44.14 mV at baseline to a mean of 66.64 mV after exercise. R-wave amplitude changed during baseline testing from a peak of 0.768 mV to 0.558 mV during non-dive apnea and a trough of 0.401 mV during dive apnea. After completing the entire exercise, students were given a post-lab Likert survey with chi-square values indicating that all responses were significant at a set of α<0.05 thresholds (Table 2).
Another claim that the lab was successfully completed within a three-hour time frame was significant at p<0.001. The third statement stating that the methods for analyzing data and results were understood was significant at p<0.001, with zero students disagreeing and only one student somewhat disagreeing. The fourth statement stating that the learning objectives were met was significant at p<0.001, with all students strongly or partially agreeing.
The fifth explanation is that the information learned would help with other higher level assessments.
Discussion
Even with a small sample size, this result supports the successful didactic demonstration of the physiological phenomenon associated with the diving response. Of the 6 groups, only 4 were able to successfully collect exhaled air in the bags provided. As the pulse rate decreased in the apnea, QT intervals increased as would be expected (Sherwood, 2013).
Noise is normal to some extent because the purpose of the ECG is to maximize the signal-to-noise ratio. If the order of breath-holding had been reversed, with apnea after physical exertion coming first, it is likely that the data would have been different. The post-laboratory survey measured participants' opinions on the knowledge gained and enjoyment of the diving response exercise.
When asked how their pulse rate responded to breath-holding during cold water immersion, two of the groups reported in their discussion questions that they thought their pulse rate increased. I assume the students lost focus at the end of Saturday's lab session, which led to an avoidable mistake like this. I assume that the participants preferred this laboratory exercise because of the nature of the experiment, which helped to keep the students engaged by including physical activity in the protocol.
This could be used to show the effect of the cold water on the diving response. The student data show that the key physiological phenomena of the diving response were successful, with heart rate decreasing during cold water face immersion and peripheral oxygen saturation decreasing during cold water. My hypothesis was that this laboratory experiment would enhance .. physiology teaching through a laboratory exercise that allowed students to think critically with their peers to understand and explain the multiple, integrative outcomes of the diving response test.
The goal was to fulfill as many of the core competencies outlined by the National Science Foundation as possible. Another competency, using quantitative reasoning, was tested in the data analysis part of the lab. With some background information and data showing that the length of breath holding was longer when they were not submerged in water than when they were submerged in water, I also tried to expose the students to the sixth competency.
Changes in end-tidal carbon dioxide and volumetric carbon dioxide as predictors of volume responsiveness in hemodynamically unstable patients.
Oxygen Saturation and the Dive Response Student Handout
Introduction
Background
Oxygen saturation is a measure of the level of oxygen bound to the hemoglobin in the blood, and can be measured via a technique called pulse oximetry. When a person holds their breath, for whatever reason, one of the body's reactions is to conserve the oxygen that is still in the blood and direct it to the brain. Ultimately, less oxygen is used in the peripherals to keep saturation levels higher for brain and heart function.
This means that the oxygen left in the blood when the breath is held lasts even longer when the face is immersed in cold water compared to air. In the event of a drowning accident, a person drowning in ice cold water would take a few minutes longer to be rescued and revived before brain damage occurs than in warm water or a person suffocating on land. By constricting the blood vessels in the arms and legs, blood flow is diverted from the limbs to the trunk and head, where oxygen is needed more.
In full-body dives, as would be the case in a drowning event, the response would be even greater in a peripheral dive. Contrary to popular belief, the physiological response that forces a new breath is actually a high level of carbon dioxide in the blood, not a low level of oxygen. The basal pressure of carbon dioxide in the body is about 40-46 mmHg systemically and about 25 mmHg in the cerebrospinal fluid (CSF).
When carbon dioxide levels become too high in the CSF surrounding the brain, the pH becomes too low. While chemoreceptors for oxygen levels are found in the aorta and carotid artery, they are not stimulated until carbon dioxide chemoreceptors have already signaled for another breath. To analyze the effect of apnea on peripheral circulation and blood oxygen saturation.
To observe the effect of exercise on peripheral circulation and blood oxygen saturation. Squeeze the bag as needed to ensure the capnometer has access to all the carbon dioxide in the bag. The equipment operator will then replay the data collected in the first part of the experiment.
The equipment operator performs an ANOVA analysis of the data collected in the second table. Mean oxygen saturation of hemoglobin in the peripheral systemic circulation of human subjects during apnea under 3 different laboratory conditions and baseline tests.
