THE EFFECT OF BODY-WEIGHT AND BODY-SURFACE AREA CORRECTION ON THE DISTRIBUTION OF THE ACT RESPONSE TO BOLUS DOSES OF HEPARIN FOR PTCA

Considerable controversy exists as to the appropriate dosing of hepari n for PTCA. We retrospectively reviewed records of 335 patients underg oing PTCA to determine: 1) the effects of correcting for weight and bo dy surface area (BSA) on the heparin dose-response distribution; and 2 ) the average dose of heparin (standard, weight-based, and BSA-based) required to achieve an activated clotting time (ACT) of 300 seconds. F or each patient, height, weight, BSA, baseline ACT (HemoTec), bolus he parin dose, and post-heparin ACT were recorded and the heparin respons e calculated. There were no significant differences in the distributio ns of standard (SD =.017 +/- 006 sec/U, 34% of mean), weight-based (SD = 1.41 +/- 0.46 sec/U/kg, 33% of mean), and BSA-based (SD = 0.033 +/- 0.011 sec/U/m(2), 32% of mean) heparin response. There were slight, b ut significant correlations between heparin response and weight (r = 0 .37) and heparin response and BSA (r = 0.36). The estimated doses of h eparin to achieve a HemoTec ACT of 300 seconds were 10,650 +/- 1270 U, 130 +/- 15 U/kg, and 5390 +/- 640 U/m(2).Conclusions. There are sligh t but significant correlations between heparin response and both weigh t and BSA. The distributions of weight- and BSA-corrected heparin resp onse are similar to that of standard heparin dosing. Thus, weight adju sted heparin dosing would not appear to be likely to provide a more re liable ACT response to bolus doses of heparin.