Increasing Circulation in the Lower Limb Under General Anesthesia Using the A-V Impulse System

Micro-mobile foot compression device compared with pneumatic compression device

BACKGROUND

A combination mechanical-pharmacologic regimen is an accepted prophylactic treatment against symptomatic venous thromboembolism for patients undergoing total hip and knee arthroplasties. Foot pumps have been recognized as effective mechanical devices. Research suggests pharmacologic prophylaxis for venous thromboembolism is associated with complications and foot pumps offer an adjunct or alternative approach. Presumably the effectiveness of foot pumps relate to enhancement of venous flow.

QUESTIONS/PURPOSES

We compared an established foot pump system with a new mobile foot pump for their ability to influence mean peak venous velocity in the common femoral, popliteal, and posterior tibial veins.

METHODS

We evaluated 60 healthy subjects with the established and the novel foot-pump systems. Ultrasonography was used to measure baseline and peak venous velocity with mechanical compression. We constructed 95% confidence intervals (CI) on the mean differences between the two devices to establish equivalence limits. We compared ratios of peak velocity to resting velocity. Subjects subjectively rated the two foot pumps with respect to size, fit, and comfort.

RESULTS

The 95% CI test for equivalence of the mean differences between the two devices was inconclusive. The novel device augmented the venous velocity 11 times greater than the resting velocity in the posterior tibial vein and three times greater than the resting velocity in the popliteal vein. The established foot pump augmented the venous velocity 15 times greater than the resting velocity in the posterior tibial vein and four times greater than the resting velocity in the popliteal vein. The novel device rated better for size, fit, and comfort when compared with the established device.

CONCLUSIONS

The established foot pump tended to be associated with greater peak velocities; the novel device produced more consistent mean peak venous velocities and may be more acceptable to patients and caregivers.

Predictive indicators of deep venous thrombosis and pulmonary arterial thromboembolism in 54 subjects after total knee arthroplasty using multislice computed tomography in logistic regression models

PURPOSE

To determine predictors of deep venous thrombosis (DVT) in the lower extremities and pulmonary arterial thromboembolism (PE) after total knee arthroplasty (TKA), we evaluated the incidence of these events using multislice computed tomography (CT).

METHODS

54 subjects (10 males, 53-81 years old, the first consecutive 25 receiving anticoagulant therapy) underwent enhanced multislice CT (MSCT) before and one week after TKA.

RESULTS

DVT, PE, and both were detected in twelve, twelve, and three subjects, respectively, one week after TKA. Hemoglobin and alveolar-arterial oxygen gradient (AaDO2) on the day after TKA, and total amount of operative bleeding (TAOB) were significantly higher in subjects with DVT or PE (P<0.05). In a logistic model for predicting DVT or PE, hemoglobin and AaDO2 levels on the day after TKA and TAOB were associated with an increased incidence of DVT or PE (relative risks 3.51, 1.19 and 1.01 (P<0.05), respectively). From box and whisker plots, we speculated the significant border to predict DVT or PE as 10.5 g/dl for hemoglobin, 34 Torr for AaDO2, and 1280 ml for TAOB. These factors also predicted DVT or PE (relative risks 5.08 (hemoglobin more than 10.5), 6.25 (AaDO2 more than 34 Torr), and 4.95 (TAOB more than 1280 ml) (P<0.05)).

CONCLUSIONS

The incidence of DVT or PE one week after TKA was 39% by MSCT. High levels of TAOB, hemoglobin and AaDO2 on the day after TKA may be predictive indicators of DVT or PE one week after TKA.