Behaviour of the Antithrombin Time After Extracorporeal Circulation of Blood

Summary

The effect on antithrombin time of equal quantities of heparin and of protamine sulfate, varies from individual to individual. There are differences in both the duration and intensity of effect. An antithrombin time which is extremely prolonged by large amounts of heparin can be restored to normal only for a few hours by protamine sulfate. When the heart-lung machine is used, the first dose of protamine sulfate, measured in mg, should exceed the total amount of heparin, also measured in mg, by at least 50—100 mg. The total amount of heparin includes both that given to the patient and that added to the blood in the heart-lung machine. If the antithrombin time has not returned to normal two minutes after the protamine sulfate injection, a second dose of 100 mg is required. For at least 24 hours after the operation the antithrombin time is measured every 1—2 hours and these determinations indicate whether further protamine sulfate is necessary. Neither fresh nor preserved blood has any influence on the heparin effect.

If these new findings are taken into consideration, post-operative hemorrhage, resultant from the addition of herapin, during cardiac operations with use of the heart-lung machine is avoidable. We shall report later on the behaviour of the thromboplastin time, the recalcification time, fibrinogen and thrombelastograms.

^* In collaboration with the cardiology departments of the Surgical Clinic (Dr. G. Rodewald) and of the II. Medical Clinic (Dr. K. D. Scheppokat), and with the department of anesthetics (Dr. K. Horatz).

• References

• (1) Thies H. A. Eine Schnellmethode zur Kontrolle der Gerinnungsverzögerung bei der Heparinmedikation. Dtsch. med. Wschr. 79: 1081-1082 1954;
• (2) Marbet R, Studer A, Winterstein A. Wirkung von Protamin auf die Blutgerinnung. Thrombose und Embolie, Ist int. Congr., Basle. 1954: 362-366 Schwabe; Basle: 1955
• (3) Thies H. A. Klinische Maßnahmen und Anwendung von Antikoagulantien in der Chirurgie. Thrombose und Embolie, 2nd Symp., Hamburg. 1958: 63-75 Schattauer; Stuttgart: 1958