Background and Aim: It was observed by the senior author over 15 years that if the foot became dependant in the 1st 48 hours after foot surgery, the patient suffered marked swelling and pain. This effect seemed less after about 48 hours. The practice was adopted of keeping the foot elevated for at least 48 hours. Aware of the work of John Tooke and Gerry Rayman with postural effects on laser Doppler skin flow, we set out to see if there was a demonstrable scientific basis for this practice.

Materials and Method: Laser Doppler flow meter was used to assess blood flow in 14 patients, (16 feet), undergoing foot and ankle surgery. Flow was recorded in the big toe, at heart level and on dependency, preoperatively, and then sequentially at 24, 48, 72 and 96 hours post operatively. Postural vasoconstriction was calculated using the formula; Postural Vas.(%)=Blood flow at heart level – Blood flow on depend./ X 100 Blood flow at heart level The time taken for blood flow in the toe to get back to the pre-operative values was assessed. Room temperature, patient temperature and patient position were all kept constant.

Results: Postural vasoconstriction was recorded for all 14 patients at 48 hours, for 7 patients at 72 hours, and for 2 patients at 96 hours post operatively. All patients had an ankle block, except 2 patients who had a popliteal block. The mean postural vasoconstriction preoperatively was 51.31%; mean at 24 hours post op. was 23.05% mean at 48 hours post op. was 36.62% and mean at 72 hours post op. was 44.24%. The mean operative time was 87.25 minutes. There was a significant difference between the pre-op levels and the 24, 48 and 72 hours post-op levels (p< 0.05). At 96 hours post-op, the difference wasn’t significant. Greater operative time was associated with less postural vasoconstriction at the 72 hours postoperatively.

Conclusion: Results showed that it takes longer than 72 hours for microcirculation to get back to normal rather than 48 hours, but the return towards normality was evident by that time. The results emphasised the importance of post-operative foot elevation for at least 48 hours due of this phenomenon. With increasing operative time, it took longer for the microcirculation to get back to normal. The longer the surgery the longer the period of elevation required. We believe that this practice minimises post operative complications; such as oedema, wound breakdown, pain on dependency. No patients suffered DVT’s or PE’s. However, patients did start with active and passive foot and lower limb physiotherapy soon after surgery.

Aim The senior author observed over 15 years that if the foot became dependant during the first 48 hours following foot surgery, the patient suffered marked swelling and pain. This effect seemed less after about 48 hours. Aware of the work of Tooke and Rayman (1986) with postural effects on laser Doppler skin flow, we set out to see if there was a demonstrable scientific basis for this practice.

Method Laser Doppler flow meter was used to assess blood flow in 14 patients (16 feet), peri-operatively. Flow was recorded in the big toe, at heart level and on dependency, pre-operatively, and at 24, 48, 72 and 96 hours post-operatively. Postural vasoconstriction (PV) was calculated using the formula:

\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[PV\ (\%)\ =\ Blood\ flow\ at\ heart\ level\ {-}\ Blood\ flow\ on\ dependency\ {\times}\ 100\] \end{document}

Blood flow at heart level

Results PV was recorded for all 14 patients at 48 hours, for seven at 72 hours, and for two at 96 hours post-operatively. The mean PV pre-operatively was 51.31%; at 24 hours post-op. was 23.05%; at 48 hours post-op. was 36.62%; and at 72 hours post-op. was 44.24%. There was a significant difference between the pre-op. levels and the 24, 48 and 72 hours post-op. levels (p< 0.05).

Significance of work It takes longer than 72 hours for microcirculation to get back to normal rather than 48 hours, but the return towards normality was evident by that time. This emphasised the importance of postoperative foot elevation for at least 48 hours due of this phenomenon. We believe that this practice minimises post-operative complications, such as oedema, wound breakdown and pain on dependency.