Fixed Dose Regimen of Heparin Administration with Activated Coagulation Time During Cardiopulmonary Bypass / 대한흉부외과학회지

BACKGROUND: The fixed dose regimen with activated coagulation time (ACT) is the most commonly employed method for determining the required dosage of heparin and protamine during cardiopulmonary bypass (CPB). MATERIAL AND METHOD: We performed a prospective study on a fixed dose regimen for analyzing adequate dosages of heparin and protamine, the incidence of heparin resistance and heparin-induced thrombocyt openia, factors affecting ACT during CPB, and changes of ACT during aprotinin usage. 300 units/kg of heparin were administered to patients, and ACTs were measured after 5 mins. ACTs were checked at 10 mins and 30 mins after the onset of CPB, and then at 30 min intervals thereafter. If the measured ACT was under 400 secs, we added 100 units/kg of heparin. The heparin was reversed with 1 mg of protamine for each 100 units administered. If the measured ACT was longer than 130 secs 30 mins after protamine administration or if there was definitive evidence of a coagulation defect, we administered a further 0.5 mg/kg of protamine. RESULT: We studied 80 patients (50 adults and 30 children) who underwent open heart surgery (OHS) at Seoul National University Hospital. Preoperative ACT was 114.3+/-19.3 secs in adults, and 119.5+/-18.2 secs in children. There were no differences in preoperative ACT due to age, body weight, body surface area, or sex. The preoperative ACT was not influenced by a positive past history of OHS. Ten adults (20%) and 3 pediatric patients (10%) needed additional doses of heparin to maintain the ACT above 400 secs. Additional protamine administration was needed in 9 adults (18%) and 10 children (33%). Heparin resistance was found in only two adults. Heparin-induced thrombocytopenia was detected in 2 adults and 1 child. During CPB, ACT was prolonged. 12 adult patients received a low dose of aprotinin and showed longer celite activated ACT compared to the control group.The kaolin activated ACT showed a lower tendency than the celite activated ACT in aprotinin users. CONCLUSION: In conclusion, fixed dose regimen of heparin and protamine can be used without significant problems, but the incidence of need of additional dosage remains unsatisfactory.

Monitoring of Activated Coagulation Time with Kaolin vs. Celite Activator in Cardiac Surgical Patients with Aprotinin / 대한흉부외과학회지

BACKGROUND: High-dose aprotinin has been reported to enhance the anticoagulant effects of heparin during cardiopulmonary bypass ; hence, som authors have advocated reducing the dose of heparin in patients treated with aprotinin. MATERIAL AND METHOD: The ACT was measured before, during and after cardiopulmonary bypass, with Hemochron 801 system using two activators of celite (C-ACT) and kaolin (K-ACT) as surface activator. From June, 1996 to February, 1997, 22 adult patients who were scheduled for elective operation were enrolled in this study. RESULT: The ACT without heparin did not differ between C-ACT and K-ACT. At 30 minutes after anticoagulation with heparin and cardiopulmonary bypass, the average C-ACT was 928+/-400 s; K-ACT was 572+/-159s (p<0.05). After administration of protamine, C-ACT was 137+/-26 s; K-ACT was 139+/-28s, which were not statistically significant. CONCLUSION: Our results showed that the significant increase in the ACT during heparin-induced anticoagulation in the presence of aprotinin was due to the use of celite as surface activator, rather than due to enhanced anticoagulation of heparin by aprotinin. We conclude that the ACT measured with kaolin provides better monitoring of cardiac surgical patients treated with high dose aprotinin than does the ACT measured with celite. The patients treated with aprotinin should receive the usual doses of heparin.

Activated Coagulation Time (ACT) Differences between Arterial and Venous Blood Samples in Patients with Open Heart Surgery / 대한마취과학회지

BACKGROUND: Activated coagulation time (ACT) is commonly used to guide heparin and protamine dosing during cardiovascular surgery. There are many factors that influence the ACT such as time of test, hemodilution, temperature, aprotinin and etc. We considered the other factor that influence the ACT, the route of blood sample. METHODS: This study included 40 patients who were scheduled for cardiac surgery. Whole blood was sampled through arterial and central venous line at 10 minutes after surgical incision and heparin administration. The ACT was measured with Hemochron 801 blood coagulation timer with 12 mg of celite surface activator. RESULTS: At 10 minutes after surgical incision and heparin administration, arterial blood and venous blood ACTs were 127 20, 537 214 seconds and 118 18, 496 145 seconds respectively (p<0.05). CONCLUSIONS: We conclude that the venous blood ACT is more less than arterial blood ACT during cardiovascular surgery.

Effects of the Dose of Protamine Sulfate Calculated by the Dose Response Curve Method or the Fixed Dose Method on the Activated Coagulation Time / 대한마취과학회지

We studied 37 patients in order to evaluate the heparin-neutralizing efficacy of the protamine dose calculated by either the fixed dose method or the dose response curve method on the activated coagulation time(ACT) during open heart surgery. According to the method calculating the protamine dose, the patients were randomly allocated to receive the protamine dose calculated by either the fixed dose method(N=17) or the dose response curve method(N= 20). The ACT was measured at immediately after sternotomy(baseline ACT) and 5 minutes after protamine administration(post-protamine ACT). There were no significant differences in baseline ACT or post-protamine ACT values between the two groups. The baseline ACT values in each group were not significantly different from those of post-protamine ACT. The patient numbers of post-protamine ACT values over 130 seconds and the differences from baseline ACT to post-protamine ACT were not significantly different between both groups. The results suggest the a dose of protamine sulfate calculated by a fixed dose method instead of a dose response curve method is available for neutralizing a heparin effect during open heart surgery.

The Change of Activated Coagulation Time during Cardiac Surgery / 대한마취과학회지

Since it's introduction by Hattersley in 1966, the acivated coagulation time(ACT) is widely used as a indicator of coagulation status of a patient during cardiac surgery. There have been many studies about the pre-heparin and post-heparin(post-protamine) ACT's, but the results vary. Comparisons of baseline ACT to postprotamine ACT revealed that there were studies which showed postprotamine ACT significantly above baseline ACT, while others were opposite. So we checked baseline ACT at three different point of time: 1) before anesthetic induction; 2) after anesthetic induction; 3) after sternotomy. We also checked postheparin and postprotamine ACT, and compared it with baseline ACTs. The postprotamine ACT showed significant increase compared with the preinduction and postinduction ACT and no significant differences between preheparin ACTs. We think that hemodilution and hypothermia might have influenced on the postprotamine ACT. It seems that baseline ACT can be measured anytime before the injection of heparin. But there are many factors which can influence the measurement of the ACT. Therefore, cares must be taken in the interpretating the result of ACT, considering the factors of ACT variability and clinical observations of blood coagulability.