A fabric pouch for maintaining transducer and catheter terminations

Management of the chronically instrumented animal is improved by enclosing the terminations of catheters and transducer wires in a subcutaneous nylon velour pouch. Six or more days after implantation, an opening is made into the pouch by removing a portion of the overlying skin; subsequent healing processes provide a satisfactory bond. Thereafter the leads can be extracted and replaced without need for anesthesia or dissection. Results in 35 animals (26 dogs and 9 monkeys) for intervals up to four months showed fibrous encapsulation was complete in 28 and partial in 7, with no mortality or significant morbidity attributable solely to the presence of the pouch. Gross and microscopic tissue examination indicated a localized foreign body reaction in response to the nylon fibers. The technique is especially useful in experimental protocols for which continuous restraint is undesirable, such as the chronically instrumented primate periodically exposed to environmental stress.