Coagulation defects during extracorporeal circulation in the dog.

Area of Science:

• Veterinary Medicine
• Cardiovascular Surgery
• Hematology

Background:

• Post-extracorporeal circulation hemorrhage is a significant complication in surgical procedures.
• Heparin is commonly used for anticoagulation but can cause adverse effects, especially in dogs.
• Understanding heparin's impact on coagulation during extracorporeal circulation is crucial for minimizing hemorrhage.

Purpose of the Study:

• To evaluate the efficacy of different heparin dosages in reducing fibrinogen deposition in oxygenators.
• To assess the coagulation defects induced by heparin during experimental extracorporeal circulation in dogs.
• To determine the optimal heparin dose for anticoagulation in canine extracorporeal circulation models.

Main Methods:

• Utilizing 99mTc-labeled autologous fibrinogen to quantify deposition in the oxygenator.
• Comparing coagulation parameters (platelet count, fibrinogen levels, PT, TT, FDPs) across three groups: no heparin, 1 mg/kg heparin, and 3 mg/kg heparin.
• Monitoring dogs undergoing experimental extracorporeal circulation.

Main Results:

• Fibrinogen deposition in the oxygenator decreased with increasing heparin dosage.
• Dogs without heparin (Group I) exhibited significant coagulation factor consumption.
• Heparin administration (Groups II and III) mitigated coagulation disorders, with some parameters remaining within normal limits.
• No significant differences in coagulation parameters were observed between the 1 mg/kg and 3 mg/kg heparin groups.

Conclusions:

• A single dose of 1 mg/kg heparin administered at the start of bypass provides adequate anticoagulation for at least 60 minutes in experimental canine extracorporeal circulation.
• This dosage minimizes fibrinogen deposition and coagulation defects, reducing the risk of post-procedural hemorrhage.
• The recommended heparin dose obviates the need for protamine neutralization, avoiding its adverse effects in dogs.