All jokes aside, our respiratory health is something most people take for granted every day. Quite literally, there is a colloquial phrase that exists to motivate people to do a task so often, that it comes as naturally as breathing. However, we do not control our breathing as much as this phrase suggests. In fact, when we are not paying attention, we do not control our breathing at all. Our autonomic nervous system performs the vital functions of inspiration and expiration for us of breathing in and breathing out. Without such a system, I surely would not want to fall asleep at night! But what happens when our respiratory health declines? How do we support people’s respiration when their bodies are not able to? Our answer is ventilators.
Ventilators take advantage of studies performed to understand people’s minimum and maximum breathing capabilities as well as appropriate gas uptake percentages to perform respiration for people when they are not able to. Let’s explore the biomechanics behind your body’s breathing and the function of ventilators, so that you can feel more confident in this machine’s capabilities to take care of you or someone you know.
Studies performed to better understand people’s minimum and maximum breathing capabilities test for their expiratory reserve volume, inspiratory capacity, and tidal volume at varying vital capacity expectations. Vital capacity expectancies are important to anticipate because they test whether participants are able to exhale an expected amount of air without taking a full breath in. By measuring a person’s expiratory reserve volume, inspiratory capacity, and tidal volume, expected vital capacities can be verified. In addition, by varying the vital capacity expectations, researchers are able to verify maximum inhalation and exhalation pressures as well as calculate lung volumes based on the volume of air present in their lungs during these times. Results from these studies are important for the appropriate functioning of ventilators because based on a person’s height and weight, ventilators will either input air based on tidal volumes, the volume of air necessary for normal inhalation and exhalation (which directly impacts lung volume), or pressure levels in instances where patients are at risk of suffering from excessively high intake pressures. Click here for an example where ventilation produces lung damage when tidal volume is greater than it should be. By knowing these volumes and capacities, patients can be appropriately treated. Click here to learn more about different types of ventilators and how they treat patients.
In addition, pressure in the lungs can be better understood by studying its tissue elastance (restriction to stretching) to ensure that the lungs do not undergo excessive stress. One study found that as the lungs’ volume increases, pressure in the lungs decreases during inhalation and increases during exhalation. Based on common knowledge regarding volume and pressure trends, it is counterintuitive to think that as lung volumes increase, pressure also increases as seen in the case of exhalation because there is more space for air particles to move around, not less. However, this trend is expected in the lungs because exhalation and inhalation utilize different tissues that tighten when their specific function is not utilized. For instance, during exhalation, when a lung is expanded, the lung experiences resistance to this expansion from exhalation tissues, therefore increasing pressure at this volume and point in a respiration cycle. By understanding the tissues’ resistance to stretching and therefore increases in pressure, we can better anticipate the time it will take for the lungs to expel air in these high-pressure cases.
Also, by sifting through gaseous concentrations for inhalation and exhalation processes, we can make appropriate ventilator gas concentration changes based on the results. For instance, if low levels of CO2 are reported during exhalation, we know to slow the respiration rate to allow more time for the body to dispel CO2 before more oxygen is inputted and the process adds onto itself instead of repeating itself.
Because normal breathing studies have been performed, we better understand how respiration works and are able to mechanically replicate it both effectively and safely. Now, you have a better understanding of how ventilators mimic your breathing patterns and can rest assured that ventilators provide this same function to those who need it.