Background: The calf muscle pump is a robust venous pump that is a major contributor to blood return from the lower extremities and has recently been found to be a predictor of venous thromboembolism (VTE).
Aims: Determine the optimal measurement parameter and cut-off value for calf pump function (CPF), as measured by venous plethysmography, to predict ipsilateral deep vein thrombosis (DVT).
Methods: Using data from the Rochester Epidemiology Project, Olmsted county residents with a venous plethysmography study and no history of venous thromboembolism were included from 1998 to 2015. The venous plethysmography parameters of each leg examined were evaluated with the outcome of interest being ipsilateral DVT after the index study using cox proportional hazard models. CPF measures were analyzed as a percent of limb refill volume (standard) or limb outflow volume, and using the crude volume refilled after exercise (toe-lifts).
Results: 1532 patients with 3062 limbs were analyzed with a median follow-up of 11.7 years. The optimal predictive cut-off for ipsilateral DVT was determined for each CPF parameter and a refill CPF +/- 23.1% demonstrated optimal prediction on univariate analysis (HR 2.57, 95% CI 1.61-4.13; Table 1). Age, body mass index, proximal deep vein incompetence (DVI), and severe hemodynamic incompetence were also significant predictors for ipsilateral DVT (p<0.05). A multivariable model was performed using refill CPF +/- 23.1% including all covariates with p-value <0.1 in univariate analysis. Reduced refill CPF <23.1% (HR 1.78, 95% CI 1.61-4.13) and proximal DVI (HR 1.73, 95% CI 1.07-2.79) were independent predictors for ipsilateral limb DVT (Table 2).
| Table 1: Continuous Variables |
HR | 95% CI | P value |
| Age | 1.03 | 1.02-1.05 | <.0001 |
| Charlson comorbidity index | 1.03 | 0.995-1.06 | 0.099 |
| Body mass index | 1.22 | 1.14-1.31 | <.0001 |
| Categorical Variables | |||
| Refill CPF (<23.1%) | 2.57 | 1.61-4.13 | <.0001 |
| Outflow CPF (+/- 18.9%) | 2.39 | 1.44-3.98 | 0.001 |
| Exercise CPF (+/- 0.54) | 2.33 | 1.44-3.78 | 0.001 |
| Female | 0.65 | 0.38-1.08 | 0.096 |
| Pulsitility | 0.55 | 0.08-3.84 | 0.55 |
| Proximal DVI | 1.67 | 1.02-2.73 | 0.04 |
| Hemodyamic Reflux Normal (ref) Mild Moderate Severe |
0.97 1.65 2.98 |
0.55-1.70 0.82-3.31 1.50-5.93 |
0.91 0.16 0.002 |
Univariate Analysis for Ipsilateral DVT per Limb
| Table 2: Variable |
HR | 95% CI | P value |
| PDR CPF (<23.1%) | 1.78 | 1.06-2.98 | 0.03 |
| Age | 1.02 | 0.998-1.04 | 0.08 |
| BMI | 1.02 | 0.98-1.06 | 0.25 |
| CCI | 1.13 | 0.99-1.28 | 0.08 |
| Hemodyamic Reflux Normal (ref) Mild Moderate Severe |
0.82 1.02 1.82 |
0.47-1.45 0.45-2.32 0.87-3.80 |
0.50 0.95 0.11 |
| Proximal DVI | 1.73 | 1.07-2.79 | 0.03 |
Multivariable Model for Ipsilateral DVT per Limb
Conclusions: CPF as measured by venous plethysmography and proximal DVI were independent risk factors for ipsilateral limb DVT in this population-based cohort study. The optimal cut-off for refill CPF for the prediction of DVT was +/- 23.1%.
To cite this abstract in AMA style:
Houghton D, Ashrani A, Liedl D, Mehta R, Hodge D, Rooke T, Wennberg P, Wysokinski W, McBane R. Optimization of Calf Pump Function Measurements by Venous Plethysmography for Prediction of Deep Vein Thrombosis [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/optimization-of-calf-pump-function-measurements-by-venous-plethysmography-for-prediction-of-deep-vein-thrombosis/. Accessed December 7, 2021.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/optimization-of-calf-pump-function-measurements-by-venous-plethysmography-for-prediction-of-deep-vein-thrombosis/