Peripheral sympathetic autoregulation in arterial calf inflow enhancement with intermittent pneumatic compression

Background: Peroperative mortality, graft failure and balloon angioplasty l imitations mitigate against active intervention for claudication, Willi the exception of exercise programmes, conservative treatments yield limited re sults. Intermittent pneumatic compression of the foot (IPCfoot) used daily for over 3 months enhances significantly the walking ability and pressure i ndices of stable claudicants; this is attributable to the significant calf inflow enhancement with IPCfoot; however, the physiologic mechanisms involv ed are only partially understood. Aims: by comparing the effects of IPC, and postural alteration on calf infl ow haemodynamics, this study examines file role of peripheral sympathetic a ntoregulation, which controls homeostasis in lower limb vessels when postur e changes, in the enhancement of calf inflow with IPCfoot in healthy subjec ts and claudicants. Material and Methods: forty-one limbs of healthy subjects (n=34; Group I) a nd 48 limbs of stable claudicants (Fontaine II) (n=42; Group II) were studi ed. The volume flow (Q), pulsatility index (PI), mean (mV), peak systolic ( PSV) and end diastolic (EDV) velocities were measured in the popliteal arte ry using duplex ultrasound in: the horizontal position, and Oil sitting wit h or without IPCfoot. Results: in Group II: median Q, mV, PSV and EDV increased by 61%, 53%, 29% and 51% respectively, and PI decreased by 20% as posture changed from sitti ng to horizontal; with IPCfoot median Q, mV, PSV and EDV increased by 70%, 58%, 22% and 75% respectively, and PI decreased by 26% (all p <0.001). In C roup I: median Q, mV, PSV and EDV increased by 125%, 115%, 51% and 38% resp ectively and Pl decreased by 30% as posture changed from sitting to horizon tal; with IPCfoot median Q, mV, PSV and EDV increased by 119%, 153%, 23% an d 46%, respectively, and PI decreased by 50% (all p <0.001). The effects of IPCfoot and postural alteration (from sitting to horizontal) did not diffe r haemodynamically (p >0.1) in both groups. Q oil lying was similar in Grou ps I and II. Oil sitting Q was higher in Group Ir [p = 0.027 (95% CI 1.7, 2 7 ml/min)]. Conclusions: the striking similarity in the haemodynamic effects of IPCfoot and postural alteration in the popliteal artery strongly suggests that the leg inflow enhancement with IPCfoot is mediated by a transient suspension of peripheral sympathetic autoregulation. In addition to their role as clin ical markers of PVD severity, the autoregulatory reflexes of peripheral cir culation appear to have functions with significant clinical implications in the management of patients with leg inflow impairment.