Opioid-induced hyperalgesia.
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Analgesics↗
Biomedical subjects
Emmanuel Guntz
Publications and source records attributed to Emmanuel Guntz.
Effects of remifentanil on N-methyl-D-aspartate receptor: an electrophysiologic study in rat spinal cord.
BACKGROUND: Remifentanil hydrochloride contained in Ultiva (GlaxoSmithKline, Genval, Belgium) has been incriminated in difficult postoperative pain management, promotion of hyperalgesia, and direct N-methyl-D-aspartate (NMDA) receptor activation, but the involved mechanisms have remained unclear. In the current study, the authors investigated the effects of remifentanil hydrochloride, with and without its vehicle, glycine, on the activation of NMDA receptors and the modulation of NMDA-induced current on neurons inside the lamina II from the dorsal horn of rat spinal cord. METHODS: To test these effects, whole cell patch clamp recordings were conducted on acute rat lumbar spinal cord slices. Considering that both components of Ultiva (remifentanil hydrochloride and glycine) could be involved in NMDA receptor activation, experiments were performed first with remifentanil hydrochloride, second with glycine, and third with the two components within Ultiva. RESULTS: Remifentanil hydrochloride does not induce any current, whereas 3 mm glycine induced a current that was abolished by the specific NMDA glutamate site antagonist D-2-amino-5-phosphonovalerate. Ultiva (remifentanil hydrochloride with its vehicle, glycine) also evoked an inward current that was abolished by D-2-amino-5-phosphonovalerate and not significantly different from the glycine-induced current. Application of remifentanil hydrochloride potentiated the NMDA-induced inward current, and this potentiation was abolished by the mu-opioid receptor antagonist naloxone. CONCLUSION: These results show that remifentanil hydrochloride does not directly activate NMDA receptors. The NMDA current recorded after application of Ultiva is related to the presence of glycine. Induced NMDA current is potentiated by application of remifentanil hydrochloride through a pathway involving the mu-opioid receptor.
Animals↗
The radial nerve should be blocked before the ulnar nerve during a brachial plexus block at the humeral canal.
PURPOSE: The brachial plexus block through the humeral canal as described by Dupré is indicated in hand and forearm surgery. This block requires a multi-stimulation technique that emphasizes the necessity of a rigorous and safe technique. Nerve injury associated with regional anesthesia can entail significant morbidity for patients. Thus, we investigated the brachial block sequence in terms of unintended nerve stimulation as a surrogate of potential nerve injury. METHODS: Sixty patients were randomly allocated in two groups of 30. In Group I the radial nerve was blocked before the ulnar nerve. In Group II the ulnar nerve was blocked before the radial nerve. During the radial nerve approach we recorded, if present, an ulnar nerve response. During the ulnar nerve approach we recorded, if present, a radial nerve response. RESULTS: In Group I while looking for the radial nerve, in 50% of the cases, an ulnar motor response was recorded. In Group II while looking for the ulnar nerve, a radial motor response was recorded in 10% of the cases. CONCLUSION: Our results indicate that the radial nerve should be blocked before the ulnar nerve when performing a brachial plexus block at the humeral canal.
Adolescent↗
Sciatic nerve block in the popliteal fossa: description of a new medial approach.
PURPOSE: Sciatic nerve blocks through lateral approaches in the popliteal fossa have been proposed. We describe a new medial approach to the sciatic nerve at this level. METHODS: After an anatomical study on six cadavers, we performed sciatic nerve blocks on 20 patients. A 100-mm insulated needle and a nerve stimulator were used; 20 mL of lidocaine 1.5% with epinephrine were injected. RESULTS: Patients lied in the supine position, the thigh flexed, abducted and rotated externally (30 degrees in all directions). The leg was flexed at 130 degrees . In this position, above the adductor tubercle, a depression known as Jobert's fossa is palpated. Through this groove, a medial approach to the sciatic nerve at the level of the popliteal fossa is possible. The mean distance between the adductor tubercle and the puncture site is 6.18 cm (range 4-8 cm) and the mean distance between the skin and the sciatic nerve is 6.62 cm (range 4-9 cm). Mean time to perform the block was 100 sec (range 55-165 sec). Complete motor blockade was obtained after a mean time of 30 min (range 5-60 min) inside the common peroneal nerve area and 43 min (range 15-75 min) inside the tibial nerve area. Motor block was complete in 17 patients and sensory block in 18 patients. No vessel puncture was observed. CONCLUSION: We describe a new medial approach to the sciatic nerve in the popliteal fossa. More studies will be required to demonstrate the technique is effective and safe.
Adrenergic Agonists↗