[Neurogenic pulmonary edema. Pathogenesis, clinical picture and therapy]

Neurogenic pulmonary edema (NPE) is a rare but always life-threatening complication in patients with central nervous system lesions. NPE is evident if patients shortly after cerebral lesions suddenly develop pulmonary edema and other causes of the symptoms, such as aspiration of gastric content, congestive heart failure and direct toxic exposure, are ruled out.

The current body of literature, partially obtained by computer-guided search (Winspirs) regarding epidemiology, pathophysiology and therapy of NPE was reviewed. Additionally, the case of a patient who developed a sudden pulmonary edema after an episode of tonic-clonic seizures is analyzed. We first provide information about history, definition, incidence and mortality of NPE. Second, a case report of a postictal NPE is presented to illustrate the clinical picture of NPE, and the applied therapeutic strategies are discussed. Third, recent pathophysiologic concepts about symptoms and possible therapeutic principles are reviewed. Fourth, a rational therapeutic plan for the prehospital emergency therapy of NPE is outlined.

The different etiologies all have one characteristic feature: an acute emergency which causes increased intracerebral pressure (ICP). NPE is known in patients after cerebral trauma, intracranial hemorrhage, stroke, intracranial tumor or seizures. The incidence is estimated at around 1% after cerebral trauma, at 71% after cerebral hemorrhage and at 2% after seizures. Mortality is appraised to lie between 60 and 100%, independent of etiology. There is a definite pathophysiologic sequence leading to NPE: a central nervous system lesion causes a sudden increase in ICP which triggers an upregulation of sympathetic signal transduction to assure brain perfusion. Increased tonus of venous and arterial vessels and of myocardial function are the immediate consequences. However, if systemic vascular resistance (SVR) increases excessively, left ventricular failure and finally pulmonary edema (NPE) may result. Additionally, the protein-rich edema fluid points to an increased endothelial permeability within the pulmonary circuit. This is thought to be caused by the acute pressure increase and by neurohumoral mechanisms, possibly similar to those described for the systemic inflammatory response syndrome (SIRS). The most important central nervous system structures involved in NPE are the medulla oblongata and the hypothalamus.

NPE is always a life-threatening symptom after increased ICP, where immediate therapeutic interventions are imperative. A rational therapeutic approach needs to be focused on decreasing ICP as primary goal. Additionally, attempts should be made to optimize body oxygenation, decrease pre- and afterload and increase myocardial contractility. Postictal patients suspicious for incipient ventilation problems must be admitted to hospital for further evaluation.