Delis KT, Nicolaides AN, Wolfe JH.
Peripheral sympathetic autoregulation in arterial calf inflow enhancement with
intermittent pneumatic compression.
Eur J Vasc Endovasc Surg 2001 Oct ;22(4):317-25

Academic Vascular Surgery, St. Mary's Hospital, London, Paddington, UK.

BACKGROUND: Peroperative mortality, graft failure and balloon angioplasty
limitations mitigate against active intervention for claudication. With the
exception of exercise programmes, conservative treatments yield limited results.
Intermittent pneumatic compression of the foot (IPC(foot)) used daily for over 3
months enhances significantly the walking ability and pressure indices of stable
claudicants; this is attributable to the significant calf inflow enhancement with
IPC(foot); however, the physiologic mechanisms involved are only partially
understood. Aims by comparing the effects of IPC(foot)and postural alteration on
calf inflow haemodynamics, this study examines the role of peripheral sympathetic
autoregulation, which controls homeostasis in lower limb vessels when posture
changes, in the enhancement of calf inflow with IPC(foot)in healthy subjects and
claudicants. MATERIAL AND METHODS: forty-one limbs of healthy subjects (n =34;
Group I) and 48 limbs of stable claudicants (Fontaine II) (n =42; Group II) were
studied. The volume flow (Q), pulsatility index (PI), mean (mV), peak systolic
(PSV) and end diastolic (EDV) velocities were measured in the popliteal artery
using duplex ultrasound in: the horizontal position, and on sitting with or
without IPC(foot). 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 sitting to horizontal; with IPC(foot)median Q, mV, PSV and EDV increased by
70%, 58%, 22% and 75% respectively, and PI decreased by 26% (all p < 0.001). In
Group I: median Q, mV, PSV and EDV increased by 125%, 115%, 51% and 38%
respectively and PI decreased by 30% as posture changed from sitting to
horizontal; with IPC(foot)median Q, mV, PSV and EDV increased by 119%, 153%, 23%
and 46%, respectively, and PI decreased by 50% (all p < 0.001). The effects of
IPC(foot)and postural alteration (from sitting to horizontal) did not differ
haemodynamically (p > 0.1) in both groups. Q on lying was similar in Groups I and
II. On sitting Q was higher in Group II [p =0.027 (95% CI 1.7, 27 ml/min)].
CONCLUSIONS: the striking similarity in the haemodynamic effects of IPC(foot)and
postural alteration in the popliteal artery strongly suggests that the leg inflow
enhancement with IPC(foot)is mediated by a transient suspension of peripheral
sympathetic autoregulation. In addition to their role as clinical markers of PVD
severity, the autoregulatory reflexes of peripheral circulation appear to have
functions with significant clinical implications in the management of patients
with leg inflow impairment. Copyright 2001 Harcourt Publishers Limited.