Clinical Trial Comparing Heparin and Protamine Fixed and Titrated Doses in Cardiac Surgery With Cardiopulmonary Bypass

Summary

There are currently several schemes described for anticoagulation with heparin and its reversal with protamine during cardiac surgery with CPB. The oldest, and most used in our routine environment, is the scheme of fixed doses, in which a bolus dose of heparin at the start of CPB is established in IU/kg of body weight and the dose of protamine at the end of CPB is calculated based on the initial dose of heparin administered.

These schemes do not take into account the variability inter-patients and can result in overdose or sub-doses of one or both drugs.

The titration schedule of doses of heparin and protamine through the principle of dose-response curve of Bull promotes individualization of dosage according to the response of each patient. This scheme has been associated with an effective reversal of the effect of heparin after CPB and with reduction of post-operatory bleeding and transfusion.

The restoration of a state of anticoagulation by heparin after its reversal by protamine is called "rebound effect". It is a phenomenon explained by the recirculation of heparin stored in the reticulum-endothelial system and connective tissue, or by free residual concentration of heparin after clearance of protamine. This effect may be present for more than 6 hours of post-operatory and may contribute to increase post-operatory bleeding.

Conditions

• Cardiac Surgery
• Cardiopulmonary Bypass
• Anticoagulation

Interventions

DRUG

Heparin fixed doses

Fixed doses of 400 units/ kg of patient's body weight before CPB to achieve an ACT \> 480 sec. Supplemental doses of 50mg of heparin if ACT \<480 sec during CPB. Reversal doses of protamine in a 1:1 ratio (1mg of protamine for every mg of heparin administered), plus 0.8mg/kg of protamine at the end of the surgery.

DRUG

PO continuous infusion of Protamine

25mg/hour in IV continuous infusion during first 6 PO hours

DRUG

Heparin and protamine titration

Titrated doses of heparin during CPB were manually calculated using Bull´s dose-response curve, which was based in periodic assessment of Activated-Coagulation Times (ACT)- baseline ACT, after 2mg/kg of heparin at cannulation and every 15 to 30 minutes during CPB. Reversal doses of protamine were calculated as a 1:1 ratio of the actual estimated heparin concentration (in mg/kg) at the end of CPB, using the Bull´s dose response curve.

Sponsors & Collaborators

• Instituto de Cardiologia do Rio Grande do Sul

  collaborator OTHER

• Fundação Universitária de Cardiologia (University Foundation of Cardiology)

  collaborator UNKNOWN

• SANE-Society of Anesthesiology

  lead OTHER

Principal Investigators

• Maria B Chuquer, M. D. · SANE-Society of Anesthesiology

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

TRIPLE

Model

FACTORIAL

Eligibility

Min Age

18 Years

Max Age

75 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2009-07-31

Primary Completion

2010-03-31

Completion

2010-11-30

Countries

• Brazil

Study Locations