Therapeutic neuromuscular paralysis in neonates: characteristic radiographic features

Neonates with respiratory distress requiring mechanical ventilation may be treated with muscular paralysis to improve oxygenation. This results in characteristic radiographic features that relate in part to the specific drug used. The radiographic signs are: bell-shaped chest, decreased bowel gas, and soft-tissue edema. When all three findings are present, the use of neuromuscular blockade can be suggested from the radiographs alone without the aid of clinical history. Radiographs of 57 infants treated with muscular paralysis and mechanical ventilation were compared to 20 infants treated with mechanical ventilation alone. In paralyzed patients, a characteristic bell-shaped chest was seen in 24 of 57 and decreased bowel gas in 46 of 52. Soft-tissue edema was seen in patients treated with metocurine, and the incidence increased with duration of therapy (18 of 25 treated for 5 or more days); it was not radiographically detected in patients treated with d-tubocurarine (0 of 13). Bell-shaped chest, decreased bowel gas, and soft-tissue edema occurred one, three, and one times, respectively, in 20 nonparalyzed control infants, and each time the findings carried significantly different clinical implications. All cases were reviewed to determine if pulmonary edema can result from mobilization of soft-tissue edema fluid after cessation of neuromuscular paralysis, and this was found not to occur.