From our anonymous insider…
Our block coordinator, a PhD in physiology, is attempting to execute a flipped classroom for the six-week cardiopulmonary and hematology block. We have about 3 hours of online lectures recorded by various physicians to watch at home every week before synthesis sessions with physicians going over cases. The coordinator assured the class that she has set it up to be the same amount of total class and lecture hours, consistent with LCME guidelines.
The main textbook resource for this year is Robbins and Cotran’s Pathological Basis of Disease. Upperclassmen recommended that we purchase a $95 subscription to Pathoma, an online organ-based video atlas covering high-yield pathologies. Many of us are watching the lectures at 1.5x speed, pausing to replay sections that are confusing or to check Wikipedia. Lanky Luke surmised, “This is the future of medical education. There are so many educational resources now. Most of our class would give up lectures if it saved $10,000 of tuition.” The five classmates at lunch immediately agreed. Gigolo Giorgio: “Half the class does not even attend lectures.” Straight-Shooter Sally: “I think it would allow medical schools to focus on emerging technologies and practical challenges in medicine. We could use that money to invest in ultrasound, EMR training, and memorable patient interactions.”
An internist specializing in viruses lectures on upper and lower respiratory infections. “I know it may not be politically correct, but the most common cause of immunodeficiency is pregnancy. Every month we have a couple 20-something-year-old pregnant women admitted requiring mechanical ventilation. They have another child in daycare that brings home RSV [respiratory syncytial virus] or the flu.” He explained how the emergence of new influenza strains commonly originate in regions of the world where there are close living situations between humans and animals hosts such as birds in Southeast Asia. Flu strains in birds produce new viral proteins that can infect human respiratory cells (genetic shift) and cause a pandemic.
A PhD respiratory physiologist from the hospital, in his late 30s, leads a workshop on mechanical ventilation with example patient cases for COPD (Chronic Obstructive Pulmonary Disease) exacerbation, pulmonary fibrosis, and asthma. Three respiratory therapists, the oldest in his mid-twenties, joined for the workshop. They were helpful in offering patient examples for our questions. A student commented, “How did they know about this career growing up in high school?” (BLS shows that respiratory therapists need an Associate’s degree and, in 2016, earned median pay of $58,670 per year.)
During a break, a classmate asks why the asthma case had normal oxygen saturation despite poor ventilation. “Hold your breath… Please don’t pass out though. [student holds breath for a few seconds.] What is making your drive to breath is not your drop in PO2 [partial pressure of oxygen]. You have enough oxygen and a high enough pressure gradient in your alveoli to maintain your blood oxygen saturation for several minutes. It is the buildup of CO2. A patient even with status asthmaticus [severe exacerbation of asthma that no longer responds to brochodilators] should have normal oxygen saturation levels. If O2 levels drop, that patient is in really bad shape.”
The respiratory physiologist explains why he got interested in physiology. “When I was a kid I had terrible uncontrolled asthma. I grew up on a farm in rural Iowa. My parents just took my occasional gasping for panic attacks. One time I had a really bad episode. Fortunately, we had come into town, and so they took me to the nearby family physician’s office where I got an inhaler.”
Before we arrived, he had connected mechanical ventilators to a dummy lung bag. In groups of three we learned about the different ventilator modes and settings. “When you place an order for mechanical ventilation, there are several things you need to include. The first step is specifying volume control or pressure control. For pressure control, you specify the peak inspiratory pressure, the rate, the fraction of inspired oxygen and the PEEP [positive end-expiratory pressure].” During inspiration from full exhalation, significant energy must be used to open compressed alveoli. Alveolar recruitment is maintained by holding the lungs at or above PEEP. “PEEP is your friend. Use it.” He demonstrated PEEP by attaching a respiratory bag to the cut trachea of a fresh pig lung. “See how difficult it is to inflate the lung when it is collapsed. [5 cmH20 PEEP added.] Now try, much easier to inflate, right?”
We also learned about plateau pressure to ensure we don’t “pop the lungs”. Lung inflation requires overcoming the resistance of the airways and stretching the lung tissue (compliance of the lung comprised of the surface tension and lung tissue matrix). “It is okay to use high pressures to overcome obstructed airways. It is not okay to use high pressures to open alveoli. That will cause barotrauma of the lung.” We learned how to measure the static lung compliance versus the airway resistance by measuring the pressure required to hold the lung at tidal volume at the end of inspiration. “If this pressure is close to the peak inspiratory pressure used to inflate the lung, most of the energy is being used to deform the lung tissue; whereas, if the plateau pressure is close to PEEP, most of the energy is consumed to drive flow through the airways.”
The next day, the same respiratory physiologist gave a lecture on obstructive and restrictive lung disease. Obstructive diseases such as asthma and smoking-related chronic bronchitis and emphysema involve an increased resistance of the airways. Patients feel that air is trapped in their lungs. Obstructive disease can be treated with inhaled steroids and Beta-2 receptor agonists, e.g., albuterol, that cause bronchiole smooth muscle relaxation. Restrictive lung diseases are commonly caused by an occupational exposure such as to asbestos, silica, beryllium, or coal dust. These particles are inhaled into the lower airways where macrophages phagocytose the microscopic particles, but the macrophages are not equipped with enzymes to degrade these particles. Over decades, the inflammation leads to the deposition of extracellular matrix proteins that stiffen the lungs and make it harder to breathe in. The only effective treatment is lung transplant.
Our patient case: Nathaniel, a 68-year-old Air Force veteran, presents to his internist for an annual check up. He was diagnosed with emphysema following a 30-year history of smoking, and pulmonary fibrosis due to asbestos exposure working as a construction foreman after the Air Force. “My wife made me quit cigarettes 20 years ago, well before any of my lung issues. Beginning in my early 60s I started to develop difficulty breathing.”
The pulmonologist explained, “Nate unfortunately has an obstructive and restrictive lung disease that combine to make his pulmonary function even worse.” A normal individual is able to exhale at least 80 percent of his or her maximum inspired volume in the first second of expiration (typically 4 out of 5 liters of lung capacity). Nate is able to expire only 30 percent within the first second. Nate is treated with inhaled steroids, a long-acting Beta-2 agonist inhaler, and a rescue albuterol inhaler as needed. These medications alleviate symptoms. (The traditional age limit for a lung transplant is 65.)
“I get out of breath if I walk up half a flight of stairs. There are a lot of activities I am just no longer able to do,” explained Nathaniel. “It makes me sad. I used to love to hunt and fish. I simply cannot do these any more. It is even difficult to take a walk with my wife.”
This block we have weekly two-hour ethics lecture led by a psychologist, ethicist, or physician (frequently a geriatrician), followed by small group discussions led by a facilitator. This week: “Ethics in the Workplace,” led by a female psychologist. When should a medical student speak up after noticing an error or unethical procedure? Should there be anonymous feedback in the medical field? The psychologist presented a peer-reviewed article that proposes a 5-step method by which a healthcare worker can determine whether to speak up:
- The nature and certainty of their judgment
- Their specific role in the situation
- The potential harm to patient
- The probable effectiveness of speaking up
- The likely cost to themselves if they speak up
The psychologist introduced the theory of “burdened courage” defined as a “system where there are rigid hierarchies, risky communications, and dysfunctional teams; and where unethical or unprofessional behaviors are ignored.” The psychologist concluded: “We should design an ethical system such that individuals who speak up are not considered heroes. Courage should not be necessary for any health care professional to ask a question or make a suggestion regarding a patient’s care. It should be the norm.”
Lanky Luke’s summary: “Who gets paid for this? I want that job.” Another student responded, “This field exists only because student loans subsidize these academics.”
Statistics for the week… Study: 10 hours. Sleep: 7 hours/night; Fun: 2 nights. Example fun: Our class held a Floyd Mayweather and Conor McGregor Fight watch party. At least 25 students attended, including several M1s. “Much better fight than the Pacquiao fight. I think McGregor did really well. He got so tired at the end.”