Venous Thromboprophylaxis With Neuromuscular Stimulation: Is It Calf Muscle Pumping or Just Twitches and Jerks?

The common peroneal nerve stimulator (CPNS) is a UK-approved device for reducing venous thromboembolism risk. It resembles a wrist watch and is placed over the common peroneal nerve to fire at 1 electrical impulse/sec. The aim was to quantify the claim that it drives the venous muscle pump and imitates walking. Twelve healthy volunteers performed 10 tip-toe maneuvers and 10 ankle dorsiflexions to imitate walking movements. The reductions in calf volume were recorded using air plethysmography (APG). The common peroneal nerve was stimulated for over 10 seconds at each of the 7 increasing electrical impulse settings, and the volume reductions were measured for comparison. The results are expressed as median (interquartile range) absolute (mL), and percentage reduction in calf volume. Tip-toe and dorsiflexion pumping maneuvers were not significantly different: 59 (33.6-96.1), 81.9% vs 51.4 (34-68.5), 59.7%, respectively ( P = .53). However, they both outperformed the CPNS: 10.8 (7.3-18), 13.2% at P = .002 and P = .002, respectively. Qualitatively, the CPNS registered on the tracings as a small spike (muscle twitch) at low settings, with larger amplitudes (ankle jerk) at higher settings. The CPNS activity spikes were discrete, lasting a median (range) of 0.24 (0.16- .3) seconds. The claim that the CPNS empties veins by pumping is supported statistically. However, the amount is small versus the tip-toe and dorsiflexion maneuvers. Furthermore, the CPNS has a short activity profile on the APG trace. Innovations that produce sustained contraction and involve the posterior calf compartments may improve pumping.