Lower Extremity Near-infrared Spectroscopy After Popliteal Block For Orthopaedic Foot Surgery

Stijn Van de Velde1, Alain F Kalmar1, *, Matthias Raes1, Jan Poelaert2, Tom Lootens3, Henk Vanoverschelde1
1 Department of Anesthesia and Critical Care Medicine, Maria Middelares Hospital, Ghent, Belgium
2 Department of Anesthesiology and Perioperative Medicine, Acute and Chronic Pain Therapy, University Hospital, Brussels, Belgium
3 Department of Orthopaedic Surgery and Traumatology, Maria Middelares hospital, Ghent, Belgium

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© Van de Velde et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 International Public License (CC BY-NC 4.0) (, which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the AZ Maria Middelares, Buitenring Sint-Denijs 30, 9000 Gent, Belgium; Tel: + 32 9 260 69 00; E-mail:



Noninvasive measurement of cutaneous tissue oxygenation using near-infrared spectroscopy (NIRS) has become common in peri-operative care. Following institution of peripheral nerve blocks, neurovascular alterations in the blocked region have been described.


The primary aim of this study encompassed the assessment of the influence of a popliteal block on changes in regional oxygen saturation (SrO2), and the location of most prominent changes.


We conducted a prospective randomised controlled trial. Hundred twenty patients who received a popliteal block for foot surgery were included. Popliteal block was performed under echographic guidance. The patients were randomized in 3 groups according to the location of the SrO2 electrodes on the legs. Bilateral SrO2 measurements were performed simultaneously. SrO2 in the operated leg and in the control leg was measured at baseline and 1, 5, 10, 15, and 30 minutes after the perineural injection. We quantified the evolution in SrO2 by calculating over time the differences in SrO2 values between the operated and control leg (=ΔSrO2).


At 30 minutes, ΔSrO2 increased significantly (p<0.05) at the plantar side of the foot (11.3% ± 2.9%), above the ankle (4.9% ± 1.3%) and the popliteal fossa (3.6% ± 1.2%).


At 30 minutes after institution of the popliteal block, ΔSrO2 was most prominent at the plantar side of the foot as compared with measurement performed above the ankle or under the knee.

Keywords: INVOS, Locoregional anaesthesia, Neurovascular effects, NIRS, Popliteal block, Tissue oxygen saturation.