IS IMPEDANCE PLETHYSMOGRAPHY A SAFE TEST AFTER TOTAL JOINT REPLACEMENT

Screening for deep venous thrombosis (DVT) following total joint repla cement (TJR) has been recommended as an adjunct to DVT prophylaxis. Th is study evaluates a structured protocol utilizing impedance plethysmo graphy (IPG) as the primary screening modality. Over a 12-month period all patients undergoing TJR of the lower extremities had an IPC 3 to 5 days after surgery. Patients received primary DVT prophylaxis with w arfarin. Minimal follow up of 6 weeks was obtained on all patients. Th ree-hundred three TJRs were performed. The IPG appeared normal in 220 of 303 patients (73%), obviating further testing. During follow-up, tw o patients had thromboembolic disease (TED). Of the 83 seemingly abnor mal IPGs, 81 were false positive compared to venous ultrasound, with s ignificantly more after knee surgery (p < 0.001). There was one confir med DVT in the abnormal IPG group and one patient died 2 weeks after d ischarge with an autopsy-proven pulmonary embolism. There was a low ov erall rate of TED (1.3%); three fourths of patients with TED presented 2-4 weeks after discharge. These results indicate that it is clinical ly safe to discharge patients who have had a normal-appearing postoper ative IPG. However, the large number of false-positive results reduces the utility of the test, particularly after knee replacement. While I PG is safe and cheaper than venous ultrasound, prophylaxis extended be yond the of hospitalization may obviate the need for screening.