Abstract
Aim of Study: To assess the efficacy of Computerised Strain Gauge Plethysmography (CSGP) to screen for proximal Deep Venous Thrombosis (DVT) following Total Knee Replacement (TKR).
Introduction: CSGP is a non invasive, bedside screening tool, used to detect the presence of proximal lower limb DVT. CSGP uses a low pressure thigh cuff to first occlude venous outflow. When the cuff is released the device is used to measure changes in calf dimensions (by means of strain gauges tied around a standardised point of the calf of the patient’s operated limb) thereby giving a measure of venous outflow. Obstruction to outflow (producing a positive result with the device) is seen with occlusion of proximal veins.
Patients & Methods: A retrospective analysis of 184 consecutive patients who had undergone primary TKR was performed. Foot pumps were used for thrombophylaxis during the erioperative period. On the fifth post operative day all patients were screened for proximal DVT using CSGP. Those with a negative result who were ambulating safely were discharged. Those with a positive test had further imaging to confirm or refute the diagnosis of proximal DVT in the operated limb. The patients’ medical notes were scrutinised for evidence of re attendances and evidence of whether proximal DVT was diagnosed following discharge from the ward.
Results: The negative predictive value of CSGP was found to be 99%. The sensitivity of CSGP for detecting proximal DVT was 83 %. The specificity was found to be 69%. The false positive rate was 92%.
Conclusion: CSGP allows the safe and prompt discharge of TKR patients who testnegative with CSGP with some degree of confidence. Patients who test positive with CSGP however require further imaging to select out those individuals who have clinically significant proximal DVT meriting full anticoagulation post operatively.
Correspondence should be addressed to: Tim Wilton, BASK, c/o BOA, The Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PE.
