Effects of positive pressure on both femoral venous and arterial blood velocities and the cutaneous microcirculation of the forefoot.
OBJECTIVE
The balance between the apparent beneficial effect and the risk of arterial ischaemia resulting from an external uniform compression is unclear. The purpose of this study was to determine the effects of a positive uniform compression on the lower limb circulation until a critical threshold was reached.


METHODS
We used Doppler ultrasound to measure femoral venous and arterial blood velocities. The effects of positive pressure on cutaneous microcirculation were evaluated by laser Doppler flux (LDF), transcutaneous oxygen pressure (tcpO2) and transcutaneous carbon dioxide pressure (tcpCO2) on the forefoot of 17 healthy subjects.


RESULTS
The results are expressed as median [lowest observed value-highest observed value]. Whereas the arterial femoral velocity (A.F.V.) decreased from 0.21 [0.08-0.36] to 0.17 [0.08-0.28] m s-1 for an external pressure as low as 10 mmHg (p < 0.001), the venous femoral velocity (V.F.V.) decreased from 0.13 [0.06-0.40] to 0.09 [0.05-0.34] m s-1 at 20 mmHg (p < 0.001). An increase of tcpCO2 from 39.8 [29.9-53.7] to 40.2 [30.0-55.5] mmHg (p < 0.05) and a decrease of LDF from 8.7 [3.1-25.9] to 5.5 [2.3-21.1] A.U. (p < 0.001) occurred at 10 mmHg. However, tcpO2 decreased only from 76.7 [40.2-91.2] to 64.6 [18.9-85.2] mmHg when the splint pressure reached 60 mmHg (p < 0.05). The observed parameters (LDF, tcpO2, V.F.V. and A.F.V.) decreased further (except for tcpCO2 which increased) up to the end of the study as the applied pressure was increased.


CONCLUSIONS
Positive pressure on the full leg provided no significant beneficial effect on femoral venous blood velocity. Whereas we showed that for an external uniform pressure as low as 10 mmHg, significant impairments in both arterial inflow of the lower limb and microcirculation of the forefoot appeared in recumbent healthy young subjects.
Fromy
B
B
Laboratoire de physiologie et d'explorations vasculaires, Centre hospitalier universitaire, Angers, France.
Legrand
M S
MS
Abraham
P
P
Leftheriotis
G
G
Cales
P
P
Saumet
J L
JL
D000328:Adult; D001783:Blood Flow Velocity; D001785:Blood Gas Monitoring, Transcutaneous; D005260:Female; D005263:Femoral Artery / Q000502:physiology*; D005268:Femoral Vein / Q000502:physiology*; D005528:Foot; D005676:Gravity Suits; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation; D012867:Skin / Q000098:blood supply*