Introduction
High-altitude pulmonary hypertension is reported in thousands of people permanently residing at a high altitude (usually more than 2000 to 2500 meters above the mean sea level). It also occurs in individuals involved in seasonal work, soldiers, and adventure activities like climbers or hikers. Genetic factors, hypoxia, and pulmonary disorders eventually lead to vasoconstriction of pulmonary blood vessels and vascular remodeling. This condition is referred to as high altitude-induced pulmonary hypertension. Patients with COPD (chronic obstructive pulmonary disease) and high-altitude pulmonary hypertension have an arterial pressure of more than or equal to 25 mm Hg (millimeter of mercury). It is the triggering point for pulmonary hypertension in COPD patients.
What Are the Causes of High Altitude-Induced Pulmonary Hypertension in COPD Patients?
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The pulmonary blood-gas barrier (oxygen exchange) is injured due to an abnormal proliferation of red blood cells in the alveoli or air sacs. It causes hypobaric hypoxia and eventually leads to high altitude-induced pulmonary hypertension.
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High altitudes, poor ventilation, abnormal heart rate, exaggerated pulmonary hypertension, insufficient production of nitric oxide, excess secretion of endothelin (endothelin maintains the tone of pulmonary blood vessels), and the inability of air sacs to eliminate irritants result in maladaptive lung response. As a result, extravascular fluid gets collected in the air sacs and impairs the breathing process.
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Impaired genes conflicting with pulmonary hypertension include hypoxia-inducible factor (HIF), pulmonary surfactant protein A1, and renin-angiotensin-aldosterone. The genetic variations continue among familial generations.
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Excess perfusion of the irritants into the alveolar-capillary barrier leads to pulmonary edema.
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Patients with thyroid disorders and myeloproliferative disorders can have pulmonary hypertension due to unclear multifactorial mechanisms.
What Are the Risk Factors Associated With High Altitude-Induced Pulmonary Hypertension in COPD Patients?
The risk factors include:
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Smoking tobacco and marijuana.
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Patients with left-ventricular failure and left ventricular hypertrophy.
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Patients with preexisting cardiac illnesses like hypertension.
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Constant exposure to indoor air pollutants.
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Individuals with sleep-disordered breathing like central sleep apnea.
What Are the Signs and Symptoms Present in COPD Patients With Altitude-Induced Pulmonary Hypertension?
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Dyspnea - A shortness of breath gradually progresses into exertion.
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Chest Pain - The patient feels discomfort in the chest during seasonal changes.
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Syncope - Patients with advanced altitude-induced pulmonary hypertension have dizziness. Severe cases result in syncope.
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Cough - Pollutants trigger cough in patients with COPD and produce blood streaks in the mucus.
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Fatigue - Fatigue after a walk or physical activity is commonly seen in patients with respiratory disorders.
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Pitting Edema - Collection of fluid in the lower extremities causes peripheral edema with pitting.
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Cognitive Impairment - Lack of oxygen leads to disorientation and cognitive impairment in patients with altitude-induced pulmonary hypertension.
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Heart Murmur - It is identified during the physical examination. Tricuspid regurgitation manifests as a murmur near the sternum.
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Ascites - The medical professional looks for the enlargement of the liver and spleen. Patients with altitude-induced pulmonary hypertension are commonly noticed with ascites.
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Systemic Sclerosis - Signs like joint pain, increased skin thickness, rashes on the face, and telangiectasia (red streaks on the skin) are present due to autoimmune disorders.
What Are the Diagnostic Procedures Performed for Patients With COPD and Altitude-Induced Pulmonary Hypertension?
The diagnostic tests used to evaluate the patients with the above symptoms are as follows;
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Electrocardiogram (ECG) - It is an inexpensive diagnostic method. It is useful to detect right ventricular hypertrophy. The enlargement of the right atrium and ventricle indicates an increase in pulmonary artery pressure that is detected in the electrocardiogram. The noninvasive method is the least effective in diagnosing mild altitude-induced pulmonary hypertension.
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Chest X-Rays - The medical professional recommends X-rays for evaluating the patient's lung with a respiratory illness like pulmonary hyperinflation due to chronic obstructive pulmonary disorder. The enlargement of the lungs can be diagnosed using radiographic images.
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Pulmonary Function Tests - It is used to diagnose the severity of altitude-induced pulmonary hypertension. The variation in ventilation and perfusion indicates pulmonary disorders. It helps to exclude other diseases like interstitial lung diseases and chronic thromboembolic pulmonary hypertension.
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Computed Tomography - Pulmonary Angiography (CT-PA) - It is used as a confirmatory diagnosis for altitude-induced pulmonary hypertension. It is a highly sensitive test. It is indicated only if the patient is clinically diagnosed with pulmonary hypertension due to high altitude and pulmonary embolism. The best results are obtained with dye-infused multidetector computed tomography. It helps to monitor pulmonary circulation and prevents the recurrence of pulmonary hypertension.
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Right Heart Catheterization - It is an important diagnostic tool for diagnosing pulmonary hypertension. It is used to evaluate the functions of the lungs and heart. Mean pulmonary artery pressure (mPAP) of more than 30 mm Hg and systolic pulmonary artery pressure (PAP) of more than 55 mm Hg is the confirmatory diagnosis for altitude-induced pulmonary hypertension.
What Are the Various Treatment Methods for Treating Patients With Altitude-Induced Pulmonary Hypertension?
Since higher altitudes are the major cause of pulmonary hypertension, individuals should migrate to lower altitudes. They usually recover within two years after migrating to lower altitudes.
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Medications - Drugs such as Sildenafil and Tadalafil are beneficial for treating patients with altitude-induced pulmonary hypertension. It helps patients with hypoxia by increasing the partial pressure of oxygen. However, it has a minimal therapeutic effect in treating hypertension. Bosentan (endothelin receptor blockers) helps to improve physical exertion. Chronic altitude sickness is managed using Acetazolamide.
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Supplemental Oxygen Therapy - A symptomatic improvement is seen in patients who are provided with a partial pressure of oxygen above 90 percent. It is delivered for several hours in hospitals using a face mask or nasal cannula. The treatment is withdrawn only if the patient can maintain 90 percent oxygen saturation while breathing atmospheric air.
Conclusion
Altitude-induced pulmonary hypertension has a high recurrence rate. It is not yet completely studied, and researchers are working on finding the major cause and development of advanced treatments, as not all people residing in high altitudes have pulmonary hypertension. The patient requires multifactorial approaches from an endocrinologist, cardiologist, sleep therapist, and pulmonologist, depending on the associated cause. Early recognition and chronic medical management provide a better prognosis. Untreated severe altitude-induced pulmonary hypertension leads to ventricular failure and death. It is important to understand people with preexisting heart conditions like high blood pressure need to keep a regular tab on their blood pressure levels. It is important to get the blood pressure under control with prescription medications. One must keep a tab on their medications and doses at regular intervals.
