New telemetric system for daily pulmonary function surveillance of lung transplant recipients

Following lung transplantation, prompt diagnosis and therapy of acute pulmonary rejection and infection episodes relies primarily upon changes in pulmonary function and determines long-term outcome. We tested a new system that allows daily monitoring of the patient's pulmonary status even after discharge from the hospital.

Seven lung transplant recipients from our center were equipped with a telemetric monitoring device consisting of a portable flowmeter and a special modem unit. The flowmeter measures forced vital capacity (FVC), forced expiratory volume per second (FEV1), and mid expiratory flows (MEFs), encodes information like fever, cough, and dyspnea in a binary code form, and stores all values in a 32 kB memory unit. After its use, the patient positions the flowmeter onto the modem unit which automatically connects to a central computer at our center to transfer all saved data. The whole set can be used via any regular phone jack. The patient's file in the computer can be checked every day.

All patients learned to use the unit during their postoperative stay or during later follow-up, and were able to apply the system at home. In a mean follow-up period of 10.3+/-2.2 months, 15 episodes of significant deterioration in home pulmonary function tests (PFTs) (>10%) were registered in 6 patients, which were all confirmed by in-hospital body plethysmography. They resulted in diagnoses of 4 episodes of acute rejection, 6 cases of beginning bacterial pneumonia, and 5 cases of, most likely, viral tracheobronchitis. Only 1 patient had to be admitted to the hospital. All patients PFTs returned to previous values after treatment.

Telemetric monitoring of graft function in lung transplant recipients allows reliable early diagnosis and treatment of infection or rejection, which might help to prevent exacerbation of the pathology and reduce quantity of amounting graft dysfunction.