Clinical History.—A 3,450-gm boy was born after a full-term pregnancy. The Apgar score was 10 at one minute, and no abnormality was detected on physical examination. The postnatal course of four days in the nursery was uneventful.
The infant was admitted to the hospital at the age of 3 weeks with a history of diarrhea and vomiting of three days' duration. Physical examination findings disclosed a well-nourished infant weighing 3,850 gm; a temperature of 36.7 C; pulse, 124 beats per minute; and respirations, 64 breaths per minute. There was no cyanosis, anemia, or edema. The chest was symmetrical in shape, but substernal retractions were noted with inspiration. Clinically, the lungs appeared to be normal, and there was no shift of the mediastinum. The heart sounds were normal, and peripheral pulses were present normally. Blood pressure in the extremities by the flush method was, right arm and left arm, 70