Oct 29, 2019
Dr. Hilary DuBrock is an Assistant Professor of Medicine with joint appointments in Pulmonary and Critical Care Medicine and Cardiovascular Medicine from Mayo Clinic in Rochester, MN.
In this episode, she discusses the importance of pulmonary rehabilitation.
Dr. DuBrock’s clinical and research interests include pulmonary hypertension (PH) and pulmonary vascular complications of liver disease. The goal of Dr. DuBrock’s research is to improve the quality of life of patients with PH and to improve the management of critically ill patients with PH and right ventricular failure.
My name is Hilary DuBrock and I am a pulmonologist at Mayo Clinic in Rochester, Minnesota and I'm a pulmonary hypertension physician who sees patients in the PH clinic here at Mayo clinic. I am particularly interested in quality of life in pulmonary hypertension, as well as specific forms of pulmonary hypertension, such as portopulmonary hypertension and chronic thromboembolic pulmonary hypertension.
Today, I'd like to talk to you a little bit about the importance of pulmonary rehabilitation.
First, I think it's important to define pulmonary rehabilitation. It's a specialized form of supervised exercise training for patients with different forms of lung disease. Before we get into the details of what pulmonary rehabilitation involves, I think it's also important to review why patients with pulmonary hypertension actually experience shortness of breath.
Shortness of breath with activity is one of the most common symptoms that patients with pulmonary hypertension experience. Since this symptom can come on over several months, many patients actually attribute their shortness of breath to aging, weight gain, or just being out of shape. Alternatively, patients can be misdiagnosed with other more common conditions, like asthma or heart disease.
So, why do patients experience shortness of breath?
The answer actually relates to the complex interaction between the heart, the lungs, the blood vessels, and the muscles. First, let's discuss the heart. In pulmonary hypertension, the right side of the heart has to pump the blood to the lungs and overcome the increased resistance to blood flow that is characteristic of pulmonary hypertension.
Normally during exercise, the cardiac output, which is the amount of blood that the heart pumps to the body, increases to keep up with the increased demands of the body. But in patients with pulmonary hypertension, this ability to increase that cardiac output is impaired. If the heart can't pump enough blood and deliver enough oxygen to the muscles and the rest of the body, then a patient with pulmonary hypertension can't keep up with activity and exercise.
The second reason relates to the lungs and breathing. One of the major functions of the lungs is to get oxygen from the air, and to eliminate carbon dioxide. Pulmonary hypertension affects the blood vessels of the lung in a way that patients actually have to breathe more in order to get rid of the same amount of carbon dioxide. This phenomenon is called ventilatory inefficiency. The lungs basically have to do more work to get the same results and then this can lead to shortness of breath when increases in ventilation or breathing are needed with exercise. Some patients can also develop low oxygen levels, which further impairs exercise capacity.
Pulmonary hypertension is actually a systemic disease. It doesn't just affect the heart and the lungs, but it's also affects the muscles of the body. This includes both the muscles involved in breathing like the diaphragm and the peripheral muscles, like the quadriceps. In pulmonary hypertension, muscles have an impaired ability to use oxygen, which can then lead to fatigue of the muscles and also limit muscle strength and endurance. As pulmonary hypertension progresses, symptoms of shortness of breath can develop with less and less activity and having symptoms of shortness of breath at rest and decreased exercise capacity are actually associated with worse survival in patients with pulmonary hypertension.
To summarize this first part, shortness of breath and pulmonary hypertension is related to numerous factors involving the complex interaction between the heart, lungs, and muscles. Together, these factors limit exercise capacity, which can then lead to fatigue, a decrease in overall conditioning level, and reduced quality of life and this can also contribute to depression and anxiety, which are common in patients with pulmonary hypertension. Despite optimal medical therapy, many patients with pulmonary hypertension still experience these symptoms of shortness of breath with activity.
So what can we do for these patients to address the complex causes of shortness of breath and exercise intolerance?
The answer is pulmonary rehabilitation.
Pulmonary rehab is a special form of supervised exercise training for patients with lung disease, including pulmonary hypertension. The specifics of different programs can vary across the country and across the world, but it's typically a 12 to 15-week in-patient or out-patient exercise program, which meets two to three times a week. Programs are typically supervised by a pulmonologist, a lung doctor, or a cardiologist, a heart doctor, and patients work with a multidisciplinary team of different providers, which includes physical therapists, respiratory therapists, and nutritionists.
Exercise programs are typically low to moderate intensity and are ideally individualized based on the patient's diagnosis and their overall conditioning level. Exercise typically involves a combination of endurance aerobic training, such as walking on a treadmill or using a stationary bicycle or cross-trainer, low resistance weightlifting exercise, typically with lighter weights and a higher number of repetitions, and breathing exercises, which may include mindfulness training or yoga.
Some exercises such as high intensity exercise and heavy weight lifting above the head are typically avoided. Patients are also cautioned about when to stop exercise, such as with the activities that cause any distressing symptoms, such as chest pain, shortness of breath, or lightheadedness or dizziness. To ensure safety, heart rate, blood pressure and oxygen saturations are monitored closely by trained providers, and emergency medical equipment is also available if needed.
In the past, exercise in patients, the pulmonary hypertension was discouraged because experts were worried about the stress of exercise on the heart. But that approach has completely changed as we've learned more about the safety and benefits of exercise in patients with stable pulmonary hypertension. In fact, the current guidelines actually recommend pulmonary rehab or supervised exercise training as an addition to PH therapy, and we know now that pulmonary rehab is safe.
In one study that summarized the outcomes of 16 different studies about exercise training in pulmonary hypertension and included over 450 patients, the risk of adverse events associated with exercise training was less than 5% and the most worrisome side effects that occurred, passing out, or syncopy, occurred in less than then 1% of patients. The risk of these adverse effects can also be minimized by ensuring that pulmonary rehab is done in a supervised setting with appropriate monitoring and in the appropriate patients.
So who are the appropriate patients?
Well, PH providers can help determine this, but appropriate patients include those who on stable and optimal pulmonary hypertension therapy. Pulmonary rehab would not be appropriate, for example, for someone who has been passing out with exercise, or who hasn't yet been started on pulmonary hypertension medical therapy. Pulmonary rehab also does not replace pulmonary hypertension therapy and should be considered as an addition to medical therapy.
So what are the benefits of pulmonary rehab?
Well, there's actually numerous benefits which extend beyond the heart and the lungs. Exercise and physical activity can benefit the entire body. In pulmonary hypertension, exercise training can increase the six-minute walk distance by approximately 60 meters, which is more than twice what experts consider a clinically significant improvement in walk distance, and it's similar or even better to the improvement that is seen with some pulmonary hypertension drugs.
Pulmonary rehab also changes the structure and function of muscles, increasing the density of blood vessels in the muscles, thus making them better at extracting oxygen and less likely to fatigue. Pulmonary rehab also improves both physical and mental aspects of quality of life, including emotional and social functioning. Lastly, pulmonary rehab has also been shown to improve pulmonary artery pressures and pulmonary vascular resistance, the obstruction to blood flow as well as function of the right side of the heart.
In summary, pulmonary rehab is a supervised exercise training program that involves a combination of endurance aerobic training, resistance exercises, and breathing exercises. In patients with pulmonary hypertension, pulmonary rehabilitation improved exercise capacity, muscle function, and quality of life, and is recommended by experts as an important adjunct to medical therapy.
My name is Hilary DuBrock and I'm aware that I'm rare.
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