Mucous plugging simulating pulmonary embolism in patients with quadriplegia.

Two quadriplegic patients suddenly lost consciousness and were found to have an elevated alveolar-arteriolar oxygen gradient. Their chest x-ray films were normal. Perfusion scintiscans of their lungs showed large areas with markedly reduced or absent perfusion. Ventilation scintiscans demonstrated absent or decreased ventilation to the hypoperfused areas, suggesting mucous plugging. In quadriplegic subjects who have an ineffective cough, acute mucous plugging can produce the sudden onset of hypoxia with essentially normal chest x-ray films, thus mimicking acute pulmonary embolism.