The aim of this study is to clarify physical therapys role in rehabilitating pulmonary hypertension (PH) patients, by explaining PH with regard to its history, etiology, prevalence, anatomy of pulmonary arteries, definition, subgroups, patophysiology, its causes, how it is diagnosed, and its signs and symptoms.
Pulmonary Hypertension was first discovered in 1981 by Dr. Ernst Von (4), but it was already getting attention in 1970s in Europe (3), and in the 1990s PH arise again in the United States along with the release of weight loss drugs (3).
The natural history of primary pulmonary hypertension was evaluated in the National Institutes of Health (NIH) registry from 1981-1987. Of the 194 patients included in the study, 63% were female and 37% were male. The mean age was 36 years, with no ethnic differences. The median survival after diagnosis was 2.5 years (2).
Pulmonary hypertension can be a result of many conditions and drugs. These include: left heart failure (diastolic dysfunction), parenchymal lung disease with hypoxia, sleep apnea, connective tissue disorders, and pulmonary embolism (1). In addition using appetite suppressants such as fenfluramine and dexfenfluramine may be associated with an increased risk of P.H.; also cocaine or amphetamine ingestion may be another contributing factor (2).
One study has shown that the frequency of PH in adults is predicted to increase, based on the high proportion of pulmonary hypertension–related deaths and hospitalizations has occurred among adults aged >65 years, especially if the patient was diagnosed with chronic heart failure (6). Another study has indicated that PH is still rare, with a prevalence of 30-50 cases per million (7); the rate of primary pulmonary hypertension is approximately 2 cases per million individuals in the general population; while secondary pulmonary arterial hypertension is dependent on its etiology (2). Most of cases of primary PH are sporadic, but 10% of them are familial (2). According to the World Health Organization, idiopathic PAH is rare and has a prevalence of 6 per million in France. PAH that is associated with other conditions has prevalence of 15 per million (15); idiopathic PAH accounts for at least of 40% of cases, and associated PAH for most of the remaining cases. IPAH is twice as common in women as in men, with a mean age of diagnosis of 36 years (7). This prevalence is higher in specific risk groups: 0.5%, in HIV infected-patient, 0.5%, in patients with sickle cell disease, and up to 16% in patients with systemic sclerosis (7).
It is critical to know the anatomy of the pulmonary arteries (PA), so the patho-physiology can be understood; the pulmonary artery’s function is to carry venous blood from the right ventricle of the heart to the lungs (9). It is one of the terminal branches of pulmonary trunk, and it is divided into the right PA and left PA (8). The RPA is longer than the LPA. The LPA pierces the pericardium and enters the hilum of the left lung, but the RPA passes transversely across the midline in the upper chest and passes below the aortic arch to enter the hilum of the right lung(8).
PH is defined as high blood pressure in the lung’s arteries and the right side of the heart (10), which can damage the lungs irreversibly, and cause failure of right ventricle(8). In normal individuals, the pressure in the pulmonary arteries is lower than the pressure in the systemic circulation, and if it has increased abnormally, it is considered as PH, which is due to constricted or stiffening of the pulmonary arteries (11).
A patient, who has pulmonary artery pressure which is higher than 25 mm Hg at rest, and more than 30 mm Hg during activity, is considered to have PH (12). The world health organization has divided PH in to five groups (12). The five group classification is a new system, because PH used to be classified into primary PH and secondary PH (12). This new system is based on the underlying cause of PH (12).
The first group of PH is pulmonary arterial hypertension (PAH); it is divided into three subtypes: familial PH, idiopathic PH, and associated PH (1). Familial PAH is inherited and a person has it in his/her genes from parents (12). Idiopathic PAH has no known cause (12). The last subtype is the associated PAH, which is caused by different conditions, such as congenital heart disease, HIV infection, diet medications, drugs, toxins, portal hypertension, thyroid disorders, and connective tissue disorders (21, 12).
The second group is PH with left heart disease (21, 11, 12). The problems that affect the left side of the heart are valvular heart disorders (mitral valve disease), and atrial or ventricular heart disorders (chronic high blood pressure) (11, 12).
The third group is PH associated with lung disorders, hypoxemia, or both. These lung conditions can be alveolar hypoventilation disorders, COPD, chronic exposure to high altitude, developmental abnormalities, interstitial lung disease, or sleep-disordered breathing.
The fourth group is pulmonary hypertension which is due to chronic thrombotic or embolic disorders, and it includes nonthrombotic pulmonary embolism (tumors, parasites, and foreign materials), thromboembolic obstruction of distal or proximal pulmonary arteries, and sickle cell anemia (21, 12).
The fifth and last group of PH is the miscellaneous type (due to vario
us other diseases or conditions), such as compression of pulmonary vessels by adenopathy, fibrosing mediastinitis, lymphangiomatosis, pulmonary langerhans’ cell granulomatosis (histiocytosis), sarcoidosis, or tumors (21, 12).
Pathophysiology of PH
As mentioned previously, PH occurs when the systolic and mean pressures in the pulmonary arteries exceed 30- 20 mm Hg, respectively (2). At some point, it hypertrophizes smooth muscles, remodels vascular walls and vasoconstricts vessels (1); this vasoconstriction is a result of increased activity of thromboxane and endothlin-1, which are considered as vasoconstrictors, and decreased activity of prostacycylin and nitric oxide as vasodilators (1). These changes and the imbalance in the production of endothelial-derived vasoactive-mediators are both vital for the causation of PH (13). The PH physiologic mechanism is either an increased pulmonary vascular resistance (PVR) or increased pulmonary venous pressure (PVP) (1). The damage of the pulmonary vascular bed or vasocnstriction due to hypoxia can lead to increased PVR, but vascular obstruction can cause PVP to increase, and increased PVP will further injure the endothelium (1), and that will develop dysfunction of the pulmonary vascular endothelium, which may worsen PH (13), because injury on the endothelium will activate coagulation at its intimal surface (1).
PH is the result of variety of factors and conditions, although in the case of idiopathic PH, the causes are not known (21, 12). Lung and heart disorders are the most common cause of PH(1). Examples are emphysema, failure of left heart ventricle, recurrent pulmonary embolism (2,12), scleredoma,(12), mitral valve disease, (13), pulmonary fibrosis, cystic fibrosis, sarcoidosis, Langerhans’ cell granulomatosis (histiocytosis), neurologic diseases involving the respiratory muscles (1), chronic low blood oxygen levels with sleep apnea. Left-sided heart failure as a cause of PH will not happen unless one of the heart valves does not work properly, the left ventricle is stressed by high blood pressure, or a heart attack or some other disorder involving the heart diminishes the ability of heart muscle to pump (1). Pulmonary and lung arteries linings undergo change at cellular level, and these changes affect artery functions, leading to lung diseases and pulmonary artery changes which include tightening of arteries walls, or these walls get stiffened at birth or from outgrowth of cells, or blood clots in the arteries; all these will make it harder for the heart to pump blood through the arteries in to the lungs (13). Other causes of PH include dermatomyositis, systemiclupuserythematosus, sarcoidosis, human immuno-deficiency virus (HIV), advanced liver disease, Sickle cell anemia (12, 13), use of anti-obesity drugs; cocaine and methamphetaminescan (2,12, 13), obesity with reduced ability to breathe (pickwickian syndrome) , extensive loss of lung tissue from surgery or trauma(1). Also PH can be genically inherited through parents (12, 13).
In a patient suspected of having PH, diagnosis is confirmed with a family history, a physical examination, and diagnostic tests, and procedures (11). The physical examination is done by auscultation, inspection of swelling in the legs and ankles (11), examination of the jugular vein in the neck for engorgement, examination of the abdomen, legs, and ankles for fluid retention, and nail beds for cyanosis (13). Diagnostic tests include electrocardiogram (ECG), chest radiography, echocardiography, testing for connective tissue disorders and other conditions, ventilation perfusion scan, pulmonary function testing, and assessment of functional status, right heart catheterization (13), pulmonary angiogram, blood test, and over night oximetry (13, 11). If the ECG indicates abnormality, it suggests right heart failure (12), and may indicate right ventricular hypertrophy and strain (13), or presence of PAH. Abnormalities include right axis deviation, right ventricular hypertrophy and strain patterns, and right atrial enlargement (13). Chest radiography indicates any enlargement in the right heart ventricle or pulmonary arteries (11, 13), and it is mostly found with idiopathic PAH patients; however asymptomatic PAH has normal radiographic findings (13). The testing of connective tissue disorders is by serologic testing, and to test the presence of conditions such as scleroderma, CREST syndrome mixed connective tissue disorder, and systemic lupus erythematosus (13). Ventilation perfusion scan is another diagnostic tool to detect blood clots in pulmonary arteries (11, 12) and it is used to diagnose and differentiate between thrombo-embolic PH and idiopathic PH (11, 13), with sensitivity of 90% to 100%, and specificity of 94% to 100% (13). Pulmonary function testing is used to diagnose chronic obstructive disease (COPD), which can be a cause of PH (11, 12); it is also used exclude airway and parenchymal lung diseases, which can contribute to the development of pulmonary hypertension, but these findings are not specific (13). The functional status of PH patient should be assessed with a 6-minute walk test and cardiopulmonary exercise test (12, 13); the 6-minute walk test determines exercise tolerance level and blood oxygen saturation level during exercise (16). A cardiopulmonary exercise test measures heart and lung functions during exercise on a bicycle or treadmill (12). The gold standard to confirm the diagnosis of P.H. is right heart catheterization (11); it is useful in assessing the severity of pulmonary hypertension (13). It is done by inserting a catheter into the femoral nerve or into the subclavian nerve. The catheter is connected to a device that can monitor and measure blood pressure in the right side of the heart and pulmonary arteries (11). Right-heart catheterization can also determine mean pulmonary artery pressure, mean right atrial pressure, and cardiac index; another use of it is excluding other etiologies of pulmonary hypertension, such asintracardiac shunting and left-sided heart disease (13). The response of certain medications, such as acute vasodilators, can be assessed during right heart catheterization (11, 13). Other additional tests used in diagnosing PH are various types of blood testing. These are complete metabolic panel (CMP) to examine liver and kidney function, autoantibody blood tests, such as ANA, ESR, and others to screens for collagen vascular diseases, thyroid stimulating hormone (TSH) screening, HIV test, arterial blood gases (ABG), complete blood count (CBC) to test for infection, elevated hemoglobin, and anemia, and B-type natriuretic peptide (BNP) (16). To detect sleep apnea nocturnal oximetry or overnight oximetry may be used; it is common to have low oxygen level during sleep with P.H. patient (12, 13, 16).
Signs and symptoms
In the early stage, PH is asymptomatic or have no specific signs or symptoms (11, 14). These symptoms and signs include cough, fatigue (11) dizziness, fainting and a bluish cast on lips and skin (14), shortness of breath, tiredness, chest pain, a racing heartbeat, feeling lightheaded, swelling in legs and ankles (12). These can be indications for any other disease. As a consequence of non-specificity, diagnosis will be delayed; and the mean time from symptom onset to diagnosis is about two years (13). The symptoms of PH are manifestations of impaired oxygen transport and reduced cardiac output, and the most frequent symptom is dyspnea, which occurs in 60% of patients (13). As symptoms advance, patients complain of dyspnea, exercise intolerance, fatigue, chest pain, and angina (13, 11). Most PH patients get right ventricular hypertrophy, followed by dilation and right ventricular heart failure (1). The symptoms of right heart failure include peripheral edema, abdominal distension, decreased appetite, early satiety, profound dyspnea, exercises intolerance (13). Other signs include systolic ejection murmur across the pulmonary valve, increased jugular venous pressure, tricuspid regurgitation, hepatomegaly and ascites, and peripheral edema (13). Other physical signs are cyanosis (point of presence of right to left shunting), decreased cardiac output, impairment in intrapulmonary gas transfer, and pulmonary congestion and left sided heart disease, while decreased breath sounds and wheezing are suggestive of fibrosis and pulmonary parenchymal disease (13).
The medical treatment program starts with the avoidance of activities that may exacerbate condition (1), and it is generally includes taking medications, making lifestyle and dietary changes, and maybe having surgery (16). Medications are also used, depending on the type and severity of PH (16).
PAH is treated by oral Ca channel blockers (verapamil), endothelin-receptor antagonist (bosentan-ambrisentan- sildenafil ), , digoxin, diuretics, and oral anticoagulants (21, 4).
The other PH types involve management of the underlying disorder. Patients with pulmonary hypertension from left-sided heart disease may need surgery for valvular disease. Patients with lung disorders and hypoxia benefit from supplemental O2 as well as treatment of the primary disorder.Patients with severe pulmonary hypertension secondary to chronic thromboembolic disease should be considered for pulmonary thromboendarterectomy. Under cardiopulmonary bypass, organized endothelialized thrombus is dissected along the pulmonary trunk in a procedure more complex than acute surgical embolectomy (1).
Vasoactive substances in general are used in treating different groups of PH. This category of medications includes prostaglandins, endothelin receptor antagonists, phosphodiesterase type 5 inhibitors, and activators of soluble guanylate cyclase (4).
The surgical solution can be one of these options, either atrial septostomy, lung transplantation, or pulmonary thromboendarterectomy (4, 16).
The PT role in PH is more rehabilitative in nature more than therapeutic, and it has different programs customized to each patient, and depends on the clinic or hospital approach. Pulmonary rehabilitation, according to “Salt lake regional medical centre”, is an outpatient program which will help the patients to learn lung self care, and easier breathing (19). In this centre, complete diagnostic testing is provided, and it includes ECG, chest x-ray, echocardiogram, pulmonary function tests, 6-minute walk tests, nuclear lung scan, CT scanning of the chest, right heart catheterization (19). In the North West therapy centre, assessment is done at the beginning by a team, including respiratory therapist, physical therapist, and social worker. The respiratory therapist focuses on breathing mechanics, education, aerobic conditioning and endurance for improved efficiency, pacing, and medication mechanics. The physical therapist helps in strengthening exercise, balance training, walking mechanics, postural education, energy conservation, assigning a home exercise program to maintain strength and coordination gains, looking for orthopedic complications to therapy, and makes appropriate adjustment to plans of treatment. The last member of the team is the social worker who is considered as a resource center for services in community. These services include helping in smoking cessation, supporting for adjustment, grief, depression, and socialization disorders, weight management, nutrition support, and cognitive behavioral therapy (20).
Pulmonary rehabilitation (21)
Since physical therapy provides rehabilitation role, the PH patient should go through a pulmonary rehabilitation program, which is an individually designed intervention program, including exercise and education that helps patients manage the symptoms of their condition and improve their level of daily functioning and well-being (3). This program will be discussed from different aspects its purpose, basic components, precaution, process, patient preparation, and expected results.
The purpose of this program is to help increase the fitness level of the patient and independent functioning, reduce dyspnea, slow down or prevent the development of disease, and improve quality of life. Pulmonary rehabilitation and cardiac rehabilitation walk complement each other because the main purpose of cardiac rehabilitation is to reverse the de-conditioning and psychosocial enhancements of pulmonary disability.
Pulmonary rehabilitation has basic treatment components and they are breathing exercise, coughing, percussion, postural drainage, and vibration. Breathing exercise helps in removing secretions, relaxation, and to increase thoracic cage mobility. This exercise is done by teaching the patient to produce a full inspiration followed by a controlled expiration, while placing a hand at the end of rib cage and under the chest for sensory feedback. Coughing is also for secretion removal but from larger airways and it is done through steps. The patient should inhale, close the glottis, contract the expiratory muscle, then open the glottis. Both breathing exercise and coughing are done when the patient restore the ability to breath normally. Percussion is usually used with postural drainage and both are used to mobilize secretions retained in lungs. Percussion is a rhythmic clapping of cupped hands over bare skin or thin material covering area of lung involvement, performed during inspiration and expiration. Postural drainage is a technique that involves gravity by positioning the patient to have the involved lung segment be the uppermost, which will assist in mobilizing the secretions. Another therapeutic technique is vibration, which is intermittent chest wall compression over area of lung involvement, performed during expiration only, and used along with postural drainage. The later three techniques are used when coughing or suctioning, breathing exercises, and patient mobilization are not adequate to clear retained secretions.
Precautions and contraindications
As with any other treatment precautions and contraindications should be taken in consideration in case of PH patients during their rehabilitation program. A patient should get full medical examination before setting the program. In some cases when a patient has a medical issue, it may interfere with the treatment and limit the exercises. In this case, the program should be modified. Conditions that may contraindicate participation in pulmonary rehabilitation include acute respiratory infection, ischemic cardiac disease, congestive heart failure, serious liver dysfunction, disabling stroke, severe psychiatric or cognitive disorders, severe pulmonary hypertension, and metastatic cancer.
Pulmonary rehabilitation is a punitive, expansive program of education, exercise, and behavior alteration, individually designed for patients with lung diseases. The rehabilitation program is designed to help patients learn more about their condition and how to concert its symptoms, as well as to take active steps, such as smoking cessation, oxygen use, and exercise. This program aims to improve the patient’s level of physical functioning, stop the advancement of the disease as much as possible, and learn how to better live with the condition. Improved physical functioning, reduction in the symptoms of the disease, and ability to fulfill activities of daily living (ADLs) more easily and independently can add to improved quality of life.
A typical program takes a few weeks to a few months, and takes to three hours per session for a few days each week. During these sessions the patient should learn to manage the program independently, as home program. Patients participating in rehabilitation could be inpatients or outpatients. A daily program should consist of two main components, and they are exercise and education.
The purpose of the exercise is to maintain or improve muscle strength, endurance and overall fitness. In order to prescribe an exercise, blood pressure, heart rate, oxygen saturation, and dyspnea levels should be evaluated, also exercise has to be monitored by physical therapists, respiratory nurses, or other qualified health care providers. A regular exercise program can upgrade overall fitness and energy, and make fulfillment of ADLs easier. The exercise program includes periods of warm-up and cool-down period, and aerobic activity.
The warm-up and cool-down periods may include stretching and light strength or resistance training.
Exercises involving upper and lower extremities are important for general fitness and for improvement in function during different activities. Some of the muscle groups used in arm and upper torso positioning serve respiratory functions, and thus upper limb exercises can also have a profitable effect on ventilation.
The aerobic exercise component is composed of activities such as walking or using a stationary bicycle, treadmill, or other equipment. Exercise is controlled by physical therapists, respiratory nurses, or other qualified health care member.
Ventilatory training may also be involved in the exercise program for certain patients. This therapy involves controlled breathing exercises, chest physical therapy techniques such as postural drainage, chest percussion, directed cough, and vibration, and training of the inspiratory muscles.
The educational component of the rehabilitation program consists of classes, manuals, and counseling or training sessions that cover different subjects, procedures, and issues, which concern patients with PH or any other chronic pulmonary disease. Education is provided by a brand of professionals, including respiratory nurses, respiratory therapists, occupational therapists, physical therapists, social workers, and dieticians. A psychologist or other mental health professional may provide counseling and direction to address mark depression, anxiety, and social isolation, which are related to symptoms of pulmonary disease. Some of the educational subjects covered include anatomy and physiology related to pulmonary function and disease, exercise theory, nutrition, techniques for using oxygen and inhalers, and ways to conserve energy. Education related to proper nutrition and weight control can be helpful, because patients may be undernourished and have muscle wasting of the respiratory muscles, which can make breathing more difficult. If anemia is present, it can decrease oxygen-carrying capacity. Electrolyte imbalances affect cardiopulmonary performance, so these and other deficits should be treated in order to enhance functioning. If patients are overweight, the extra weight increases oxygen and energy consumption and may increase fatigue. Patients who have not yet ceased smoking should be strongly encouraged to do so.
After being referred and examined by a physician, a medical history of the patient should be taken by the rehabilitation team, and some tests must be done prior to the rehabilitation program. These tests are pulmonary function tests (PFTs), chest X-rays, arterial blood gas (ABG) analysis, pulse oximetry, and sputum examination. PFTs are performed with a spirometer to measure lung performance and indicate the presence and extent of lung disease. A chest X-ray can show emphysema and other lung disease, including lung cancer, for which there is increased risk among smokers with pulmonary disease. Pulse oximetry helps determine when supplemental oxygen is required and measures oxygen in the blood. Exercise tests may be used to prescribe the length and intensity of the exercise.
Risk of complications such as muscle injury or cardiac reactions is always come up with exercise, but will be eliminated by careful exercise prescription and monitoring. Disease-related complications that should be monitored include fever, unusual or extreme shortness of breath, irregular pulse, unanticipated weight changes, gastric complaints, or any other change that is unusual for the patient.
Pulmonary hypertension is indicated when pulmonary artery pressure is higher than 25 mm Hg at rest, and more than 30 mm Hg during activity. PH is due to constricted or stiffening of the pulmonary arteries. PH is classified in to five groups, based on the underlying cause. PH is asymptomatic or has no specific signs or symptoms, but later, the patient may complain of dyspnea, exercise intolerance, fatigue, chest pain, and angina. PH treatment protocol consists of making lifestyle and dietary changes, medications, rehabilitation program, and maybe having surgery. Physical therapy plays an important role in rehabilitating PH patients. PT aims to help increase the fitness level of the patient and independent functioning, through exercise programs and education.