Validation of a radiotelemetry system for continuous blood pressure and heart rate monitoring in dogs.

A blood pressure telemetry system with catheter placement in the femoral artery was evaluated over a 119-day period in eight mongrel dogs. Every 3 weeks, the pressures recorded by telemetry were compared with direct, simultaneously recorded blood pressures measured from a femoral artery catheter implanted on the contralateral side. One telemetry device failed within 1 week of implant and was replaced before the beginning of data collection. Continuous blood pressure measures were accurate for a minimum of 17 weeks in all eight dogs. Acute changes in blood pressure and heart rate were not evaluated. Validation by simultaneous recording with a physiological monitor indicated that there was no drift in the telemetry blood pressure or heart rate during the 17-week period. Heart rates recorded by telemetry and a physiological monitor were identical, as were mean arterial pressures. The systolic pressure measured by the physiological monitor was consistently higher than that measured by telemetry. This may have been due to differences in the compliance of the catheter material in the two systems. Two devices failed within approximately 6 months of implant, apparently because of exhaustion of the battery. These findings indicate that this telemetry device can be used for periods of up to 17 weeks without appreciable drift or attenuation of the blood pressure signal. The results also describe a validation procedure for monitoring the accuracy of the telemetry system over extended periods of use. We conclude that this telemetry device can be used for the long-term assessment of blood pressure and heart rate in the dog.