Preparing the Circuit The complete perfusion circuit consists of a low flow modular pump, arterial and venous tubing, an oxygenator with an arterial line filter, a heating and cooling unit and an arterial blood temperature probe.
The circuit is primed with a mixture of your own blood and an electrolyte (mineral) solution, which circulates through the isolated limb with very high concentrations of oxygen. Heparin, a substance that prevents blood from clotting, is added. Leakage of the perfusate into the general circulation is checked by injecting fluorescein dye into the mixture, and any leakage is monitored and corrected during the operation.
Special thermometers (needle thermistors) are placed in the soft tissues at strategic locations to record the temperature of the limb during the procedure.
Giving the Drug The perfusate temperature is raised to 42 º C (107.6 º F). The temperature of the extremity is raised to 40 º C (104 º F) and is not allowed to rise beyond that.
When the average temperature near the tumor is 39 º C (102.2 º F), the chemotherapy drug is added to the solution and the perfusion continues for one hour (tourniquet time is limited to a maximum of two hours). Flow rates are in the range of 400 to 600 cc/mint. for a leg and 250 to 350 cc/mint. for an arm, with perfusion pressures never allowed to exceed the average blood pressure in the body.
When the procedure is complete, the drug is drained from the arm or leg and the limb is washed out with a mixture of dextran-40 and a balanced salt solution.
