Pulmonary hypertension is a general term used to describe a hemodynamic state defined as a resting mean pulmonary artery pressure at or above 25 mm Hg. Pulmonary hypertension (PH) is characterized by elevated pulmonary arterial pressure and secondary right heart ventricular failure. PH may be suspected in a patient with dyspnea on exertion; however, it is difficult to measure pulmonary pressures noninvasively. Previously, patients were classified as having primary or secondary PH; however, patients currently are classified by the World Health Organization (WHO) into five groups based on the mechanism. Conditions such as collagen vascular disease, congenital heart disease, anorexigenic medications (specific appetite depressants), chronic use of stimulants, portal hypertension, and HIV infection increase the risk of PH in susceptible patients.
Vascular injury occurs with endothelial dysfunction and vascular smooth muscle dysfunction, which leads to disease progression (vascular smooth muscle hypertrophy, adventitial and intimal proliferation [thickening of the wall], and advanced vascular lesion formation). When the pulmonary vascular bed is destroyed or obstructed, its ability to handle the blood volume received is impaired. The increased blood flow increases the pulmonary artery pressure and pulmonary vascular resistance and pressure (hypertension). This increases the workload of the right ventricle, leading to right ventricular hypertrophy (enlargement and dilation) and, eventually, right heart ventricular failure.
Complete diagnostic evaluation includes a history, physical examination, chest x-ray, pulmonary function studies, ECG, echocardiogram (to estimate the pulmonary artery systolic pressure as well as to assess atrial and ventricular sizes, thickness, and function), ventilation-perfusion scan, sleep studies, autoantibody tests (to identify diseases of collagen vascular origin), HIV tests, liver function testing, and cardiac catheterization. Right heart catheterization is necessary to confirm the diagnosis of PH and accurately assess the hemodynamic abnormalities: PH is confirmed with a mean pulmonary artery pressure greater than 25 mm Hg.
The goal of treatment is to manage the underlying condition related to PH of known cause. Most patients with PH do not have hypoxemia at rest but require supplemental oxygen with exercise. Therapies are tailored to the patient's individual situation, functional New York Heart Association class, and specific needs, and include diuretics, oxygen, anticoagulation, digoxin, and exercise training. Oxygen therapy reverses vasoconstriction and reduces the PH in a relatively short time.
Pharmacologic Therapy
- Anticoagulation should be considered for patients at risk for intrapulmonary thrombosis.
- Digoxin may improve right ventricular ejection fraction in some patients and may help to control heart rate; however, patients must be monitored closely for potential complications.
- Different classes of medications are used to treat pulmonary hypertension; these include calcium channel blockers, phosphodiesterase-5 inhibitors (e.g., sildenafil [Revatio, Viagra]), endothelin antagonists (e.g., bosentan [Tracleer]), and prostanoids (e.g., epoprostenol [Flolan], treprostinil [Remodulin], and iloprost [Ventavis]). The choice of therapeutic agents is based on the severity of the disease.
- A small number of patients with pulmonary hypertension respond favorably to acute vasodilation and do well with a calcium channel blocking agent. Calcium channel blockers have a significant advantage over other medications taken to treat PH in that they may be taken orally and are generally less costly.
- The oral medications sildenafil (Revatio, Viagra), tadalafil (Cialis, Adcirca), and vardenafil (Levitra) are potent, specific phosphodiesterase-5 inhibitors that degrade cyclic 3′,5′-guanosine monophosphate (cGMP) and promote pulmonary vasodilation.
- Endothelin receptor antagonists such as bosentan (Tracleer) are potent vasodilators and improve exercise ability. Other selective endothelin receptor antagonists include sitaxsentan (Thelin) and ambrisentan (Letairis).
- Prostanoids mimic the effect of the prostaglandin and relax the vascular smooth muscle. Prostanoids used to treat PH include epoprostenol (Flolan), treprostinil (Remodulin), and iloprost (Ventavis); however, these have limitations owing to a short half-life.
Surgical Management
Lung transplantation remains an option for all eligible patients whose disease is refractory to medical therapy. Bilateral lung or heart-lung transplantation is the procedure of choice. Atrial septostomy may be considered for selected patients.
Outline
- Identify patients at high risk for developing pulmonary hypertension (e.g., those with chronic obstructive pulmonary disease, pulmonary emboli, congenital heart disease, and mitral valve disease).
- Be alert for signs and symptoms of PH.
- Administer prescribed oxygen therapy appropriately.
- Inform and instruct patient and family about home oxygen supplementation.
- For patients treated with prostanoids, educate patient and family about the need for central venous access (epoprostenol) and subcutaneous infusion (treprostinil) as well as proper administration and dosing of the medication, pain at the injection site, and potential severe side effects.
- Address emotional and psychosocial aspects of this disease with the patient.
For more information, see Chapter 23 in Hinkle, J. L., & Cheever, K. H. (2018). Brunner and Suddarth's textbook of medical-surgical nursing (14th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.