Is Impedance Plethysmography a Safe Test After Total Joint Replacement?

Screening for deep venous thrombosis (DVT) following total joint replacement (TJR) has been recommended as an adjunct to DVT prophylaxis. This study evaluates a structured protocol utilizing impedance plethysmography (IPG) as the primary screening modality. Over a 12-month period all patients undergoing TJR of the lower extremities had an IPG 3 to 5 days after surgery. Patients received primary DVT prophylaxis with warfarin. Minimal follow up of 6 weeks was obtained on all patients.Three-hundred three TJRs were performed. The IPG appeared normal in 220 of 303 patients (73%), obviating further testing. During follow-up, two patients had thromboembolic disease (TED). Of the 83 seemingly abnormal IPGs, 81 were false positive compared to venous ultrasound, with significantly more after knee surgery (p < 0.001). There was one confirmed DVT in the abnormal IPG group and one patient died 2 weeks after discharge with an autopsy-proven pulmonary embolism. There was a low overall rate of TED (1.3%); three fourths of patients with TED presented 2-4 weeks after discharge.These results indicate that it is clinically safe to discharge patients who have had a normal-appearing postoperative IPG. However, the large number of false-positive results reduces the utility of the test, particularly after knee replacement. While IPG is safe and cheaper than venous ultrasound, prophylaxis extended beyond the of hospitalization may obviate the need for screening. [ABSTRACT FROM PUBLISHER]