MANAGEMENT OF SECONDARY PULMONARY HYPERTENSION IN ICU

Abstract

PH is defined as an increase in mean pulmonary arterial pressure (PAPm) ≥25 mmHg at rest as assessed by right heart catheterization. The importance of pulmonary hypertension is that many medical disorders managed in the intensive care unit (ICU) are associated with an elevation of pulmonary arterial pressure (PAP). Usually this is transient, of mild to moderate severity and not considered to affect patient outcome. However, serious and prolonged elevation of PAP progresses to severe acute pulmonary hypertension leading to life threatening complicationsincluding refractory systemic arterial hypotension, severe hypoxemia, right ventricular (RV) dysfunction and failure resulting in cardiogenic and/or obstructive shock and death. Unfortunately, in most cases acute pulmonary hypertension remains under diagnosed and is usually recognized when the patient develops obvious signs of progressive RV failure. Pathological changes in each segment of the pulmonary vasculature is characterized by progressive increase in pulmonary arterial pressure in association with variable degrees of pulmonary vascular remodeling, vasoconstriction, smooth muscle proliferation with or without neointimal formation and in situ thrombosis formation and in situ thrombosis. Cardiac disorders, pulmonary diseases, or both in combination are the most common causes of secondary pulmonary arterial hypertension (SPAH). Massive PE, sepsis, ARDS and ALI are the main causes of acute arterial pulmonary hypertension in the adult patientbut also occur in Pulmonary veno occlusive disease Preexisting pulmonary hypertension is one of the major risk factors for morbidity and mortality in cardiothoracic surgery patients and major determinant of perioperative morbidity and mortality in special situations such as heart and lung transplantation, pneumonectomy, and ventricular assist device placement. The most important tools for diagnosis of pulmonary hypertension are Pulmonary artery catheterization which is considered a gold standard for the diagnosis of pulmonary hypertension, CT, pulmonary angiography and Echo-cardiography. Cor pulmonale is the most important consequence of pulmonary hypertension and remains a frequent cause of RV failure and death in patients with arterial pulmonary hypertension. Basic principles of ICU management of patients with PH and RV failure include the treatment of triggering factors, optimization of fluid balance (usually with i.v. diuretics), reduction of RV afterload with Pulmonary vasodilator therapy (usually with parenteral prostacyclin analogues, but sometimes also with Phosphodiesterase type 5 inhibitors and Inhaled Nitric oxide), improvement of CO with inotropes (with dobutamine) and maintenance of systemic blood pressure with vasopressors, if necessary. Specific drug therapy for management of pulmonary hypertension includes calcium channel blockers, endothelin receptor antagonists, phosphodiesterase type 5 inhibitors and prostacyclin analogues and prostacyclin receptor agonistssupportive therapies also are recommended in management of pulmonary hypertension like diuretics, anticoagulation, oxygen therapy digoxin and other cardiovascular drugs. Right ventricle assistance should be consideredfor selected patients with PH and RV failure and lung transplantation in refractory cases to medical treatment.