A NOVEL METHOD FOR CHRONIC MEASUREMENT OF PLEURAL PRESSURE IN CONSCIOUS RATS

Pleural pressures are used to evaluate lung function and are generally measured acutely in anesthetized animals. Previous attempts to measur e pleural pressure chronically in conscious animals have involved surg ical implantation of pressure-sensitive catheters directly into the pl eural cavity. The success of these techniques has been limited by lung damage and/or tissue growth and encapsulation of the pressure-sensiti ve catheter with damping or loss of the signal. These problems have be en eliminated by developing a novel surgical procedure for placement o f a pressure-sensitive catheter beneath the pleural surface. The cathe ter (attached to a radiotelemetry transmitter) is surgically implanted beneath the serosal layer of the esophagus within the thoracic cavity . This is accomplished by making a small incision in the serosal layer of the esophagus caudal to the diaphragm and advancing the catheter c ranially into the thoracic cavity until pressure changes are maximal. The accuracy of these measurements was verified by comparison with dir ect pleural pressure measurements over the range of -3 to -34 cm H2O T he pleural pressure changes remained constant for at least 14 weeks fo llowing surgery, and there was no evidence of tissue damage or growth around the catheter. This novel method for measuring pleural pressure chronically in conscious rats will facilitate evaluation of the effect s of drugs, environmental agents, or disease on respiratory function b y allowing repeated and simultaneous measurements of both ventilatory (breathing) patterns and lung function in conscious animals. (C) 1998 Elsevier Science Inc.