Shock of anaphylactoid type induced by protamine: a continuous cardiorespiratory record.

The intravenous administration of protamine to a patient after cardiac bypass caused a sudden increase in airway resistance and lung stiffness, and a severe drop in arterial blood pressure. The ventilatory obstruction reached its maximum after 30 s and had returned almost to normal in 3 min. Arterial hypotension with low pulse amplitude, decreased heart rate and ST depression in the ECG tracing developed 1.5 min after the respiratory symptoms. In spite of rapid blood transfusion, arterial pressure reached a low level after 5 min, but rose after isoprenaline administration. It is suggested that changes in the vascular and respiratory compartments occur in parallel with, but independently of, myocardial injury and depressed cardiac contractility.