Sudden Loss of Consciousness, Dyspnea, and Hypoxemia in a Previously Healthy Young Man

Abstract

A previously healthy 37-year-old man had a sudden syncopal episode that lasted an estimated 10 seconds. The patient’s wife, who witnessed the event, said that his eyes rolled back and that he urinated but had no tonic-clonic activity. On regaining consciousness, he complained of dizziness, shortness of breath, and sweating. An emergency medical service then brought him to the hospital. In the emergency department, the patient complained of shortness of breath but denied chest pain, cough, fever, headache, weakness, or previous neurological difficulty. He had no significant past medical history and had been well before losing consciousness. On physical examination, the patient was alert and oriented but anxious and dyspneic. His oral temperature was 99°F; pulse, 115 bpm and regular; blood pressure, 105/70 mm Hg; and respirations, 20 breaths per minute. Cranial nerve function and optic fundi were normal. Neck veins were not distended, and the precordium was quiet, with normal heart sounds and no murmurs. Lungs were clear to auscultation. Abdominal findings were unremarkable, and the extremities had full, equal pulses with no edema. The chest radiograph and ECG obtained at entry appear in Figs 1⇓ and 2⇓, respectively. Arterial blood gas analysis (room air) disclosed a pH of 7.46, a Paco2 of 30 mm Hg, a Pao2 of 52 mm Hg, and an O2 saturation of 89%. Results of the following laboratory studies were normal: complete blood count; urinalysis; serum creatinine, calcium, phosphorus, and electrolytes; blood sugar and urea nitrogen; and liver function tests. Figure 1. Chest radiograph showing prominent central pulmonary arteries with abrupt tapering of the lower lobe branches (especially the left), possible …