Non-Cardiogenic Pulmonary Edema

Abstract

Pulmonary edema (PE) remains one of the more common reasons for admission to the hospital. Pulmonary edema is either cardiac or non-cardiac. The cardiac causes of pulmonary edema occur because the cardiac pump function has failed and there is increased capillary hydrostatic pressure secondary to elevated pulmonary venous pressure. Cardiogenic pulmonary edema is the accumulation of fluid with a low-protein content in the lung interstitium and alveoli and occurs when the pulmonary venous and left atrial venous return exceeds left ventricular output. Most often this is due to left heart failure, cardiac valve disease, volume overload, kidney failure or cardiac tamponade. Non cardiogenic pulmonary edema (NCPE) is a condition that is associated with high morbidity and mortality. Pulmonary edema fluid accumulates in the lungs through damaged capillary endothelial cells and this leads to impaired gas exchange (oxygen and carbon dioxide) with hypoxia and respiratory failure. The best example of non-cardiogenic pulmonary edema is acute respiratory distress syndrome (ARDS) (Sartori et al, 2010). ARDS is a serious condition of hypoxia, bilateral lung infiltrates on chest roentgenogram with subsequent respiratory failure. The hallmark of ALI (acute lung injury)/ARDS on the cellular level is pulmonary capillary endothelial cell permeability and fluid leakage into the pulmonary parenchyma, followed by neutrophils, cytokines and an acute inflammatory response. It is associated with a high morbidity and 30-50% mortality. ARDS has multiple causes with the most common being sepsis or pneumonia, less common causes of ARDS with ensuing pulmonary edema are trauma or pancreatitis (Ware & Mathay, 2005). Other causes of NCPE in hospitalized patients are intravenous fluid with volume overload, neurogenic pulmonary edema, reperfusion pulmonary edema, re-expansion pulmonary edema, opiate overdose, salicylate toxicity. Less common, forms of NCPE are high altitude pulmonary edema (HAPE), immersion pulmonary edema and negative pressure pulmonary edema (NPPE).