Jean-Pierre Lecoq

Thromboprophylaxis in microsurgery

Abstract Microsurgical free tissue transfer has become a gold standard in a wide range of clinical situations. Thrombosis at the anastomotic site is not only the most common cause of failure of microsurgical operations, but it is also one of the factors resulting in microcirculatory intravascular thrombosis in free flaps. All conditions of thrombus formation, defined by Virchow in 1856, are encountered in free flap surgery. This literature review concerns the problem of thromboprophylaxis in microsurgery. All citations published this last ten years (1996–2005) concerning this problem are noted. Data are confronted with other specialties, particularly vascular surgery, or with large retrospective studies. Protocol used in our institution is presented at the end of this lecture.

Effect of epidural bupivacaine on the relationship between the bispectral index and end‐expiratory concentrations of desflurane

We compared the relationship between the bispectral index and end‐tidal desflurane concentrations in 20 patients undergoing elective surgery. Patients received epidurally either 10 ml saline (group S) or 10 ml bupivacaine 0.125% with epinephrine 1/800 000 (group B) before induction of anaesthesia with sufentanil (0.15 μg.kg−1) and propofol (2 mg.kg−1); muscle relaxation was obtained with cisatracurium (0.2 mg.kg−1). Patients lungs were ventilated to maintain end‐tidal desflurane at 3% in O2/N2O (50/50) until 5 min after skin incision, followed by two consecutive 10 min periods at end‐tidal desflurane 6% and 9%. bispectral index values were recorded before induction, at 3% desflurane before and 5 min after skin incision, and at 6% and 9% end‐tidal desflurane. Bispectral index decreased with increasing end‐tidal desflurane concentration (anova: p < 0.05). The decrease in bispectral index was significant between pre‐induction, 3% and 6% desflurane. No significant difference was observed at 3% desflurane before and after skin incision, or between 6 and 9% desflurane. The relationship between bispectral index and end‐tidal desflurane concentration was fitted by a linear regression in each group. No significant difference in bispectral index was observed between the groups at any time. We conclude that bispectral index decreases with increasing desflurane concentration and that this relationship is not affected by epidural 0.125% bupivacaine.

Norepinephrine and ephedrine do not counteract the increase in cutaneous microcirculation induced by spinal anaesthesia

BACKGROUND Neuraxial anaesthesia improves tissue perfusion and tissue oxygen tension. Vasodilation induced by this technique may result in hypotension requiring the administration of vasoactive drugs. The use of peripheral vasoconstrictors might counteract the improved tissue perfusion and its potentially beneficial effects. We therefore investigated the effect of i.v. norepinephrine and ephedrine on skin perfusion using laser-Doppler flowmetry (LDF) in patients during spinal anaesthesia. METHODS Skin blood flow expressed in perfusion units (PU) provided by LDF was measured simultaneously at the foot and the manubrium levels in 44 patients during spinal anaesthesia with a sensory level below T5. Norepinephrine infusion was then titrated to normalize mean arterial pressure (MAP) in 23 patients (Group NOR). Ephedrine (max. 10 mg) was administered in 21 patients (Group EPH). Changes in relative PU were compared between the two sites of measurements in each group during drug administration. The same doses of norepinephrine were assessed in 11 normal volunteers to assure comparable vasoreactivity at the foot and manubrium levels. RESULTS Spinal anaesthesia resulted in a 10% decrease in MAP (P<0.001), an increase in relative PU values at the foot level (P<0.001), and a decrease at the sternum level (P<0.05). Norepinephrine and ephedrine produced a significant increase in relative PU values at the foot level when compared with the sternum level (NOR: P=0.02; EPH: P=0.0035). In volunteers, norepinephrine decreased cutaneous perfusion similarly at the manubrium and foot levels. CONCLUSIONS Improved skin perfusion induced by spinal anaesthesia was not counteracted by the use of norepinephrine or ephedrine.

Interfascial Spread of Injectate After Adductor Canal Injection in Fresh Human Cadavers.

The adductor canal block has become a common analgesic technique in patients undergoing knee arthroplasty. Dispersion of local anesthetic outside the adductor canal through interfascial layers and blockade of smaller nerves that confer innervation to the knee could contribute to the analgesic efficacy of the adductor canal block. We studied the diffusion of local anesthetic mixed with dye after injection into the adductor canal in fresh human cadavers. In all 8 legs, injectate was found in the popliteal fossa in contact with the sciatic nerve and/or popliteal blood vessels. Interfascial spread patterns were identified.