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Nilufar Foadi,1,* Matthias Karst,1,* Anika Frese-Gaul,2 Niels Rahe-Meyer,3 Stefan Krömer,1 Christian Weilbach 4 1Department of Anesthesiology and Intensive Care Medicine, Pain Clinic, Hannover Medical School, Hannover, 2Department of Psychosomatic Medicine, AHG Psychosomatische Klinik Bad Pyrmont, Bad Pyrmont, 3Department of Anesthesiology and Operative Intensive Care Medicine, Franziskus Hospital, Bielefeld, 4Department of Anesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Medicine, St. Josefs‑Hospital Cloppenburg, Cloppenburg, Germany *These authors contributed equally to this work Objective: In orthopedic surgery, it is well known that the use of intrathecal morphine (ITM) leads to an improved quality of postoperative analgesia. Little is known how this improved analgesia affects the long-term course after surgery.Study design: A randomized, double-blind trial.Setting: Academic medical center.Subjects: Forty-nine patients undergoing total hip or knee replacement surgery in spinal anesthesia.Methods: Patients were randomly assigned to receive either 0.1 mg (n=16) or 0.2 mg (n=16) morphine sulfate intrathecally or physiological saline (n=17) added to 3 mL 0.5% isobaric bupivacaine for spinal anesthesia. As a function of the quality of the short-term postoperative analgesia, the effect on recovery and quality of life was evaluated at various time points up to 26 weeks after surgery.Results: In both ITM groups, the additionally required postoperative systemic morphine dose was significantly reduced compared with the placebo group (P=0.004). One week after operation, patients with ITM reported significantly less pain at rest (P=0.01) compared to the placebo group. At discharge, in comparison with the 0.1 mg ITM and placebo group, the 0.2 mg ITM group showed a higher degree of impairment regarding pain, stiffness, and physical function of the respective joint (P=0.02). Over the further follow-up period of 6 months after surgery, recovery and the quality of life did not differ significantly between the three study groups (P>0.2).Conclusion: Morphine (0.1 mg) as adjunct to 0.5% bupivacaine for spinal anesthesia is effective to produce a pronounced postoperative analgesia with a beneficial analgesic effect up to 1 week after surgery. With this study design, the different quality of postoperative analgesia had no effect on quality of life and recovery in patients over the 6-month follow-up period. In the medium term, ITM may induce hyperalgesic effects. Keywords: intrathecal opioid, adjunct, perioperative analgesia, long-term outcome, recovery

Christian Weilbach,1 Christian Hoppe,2 Matthias Karst,3 Michael Winterhalter,4 Konstantinos Raymondos,3 Arthur Schultz,3 Niels Rahe-Meyer2 1Department of Anesthesiology, Intensive Care, Emergency Medicine and Pain Therapy, St. Josefs-Hospital Cloppenburg, Cloppenburg, 2Clinic for Anesthesiology and Operational Intensive Care, Franziskus Hospital Bielefeld, Bielefeld, 3Clinic for Anesthesiology and Intensive Care, Medizinische Hochschule Hannover, Hannover, 4Clinic for Anesthesiology and Pain Therapy, Klinikum Bremen-Mitte, Bremen, Germany Background: Topical anesthesia is used to control pain associated with many procedures in medicine. Today, the product most commonly applied for topical anesthesia in Germany is EMLA® (lidocaine/prilocaine). However, since prilocaine is a methemoglobin-inducing agent, there are limitations to its use, especially in neonates and infants. The aim of this study was to evaluate the effect of prilocaine and lidocaine as well as propylene glycol, a penetration enhancer, and trometamol, a buffer substance, in anesthetic creams.Patients and methods: Twenty-nine healthy adults participated in this study. Standardized creams with eight different compositions were applied and left for 20, 40 or 60 min. After exposure to standardized painful stimuli (blunt/sharp with pressures of 0.2, 0.4 or 0.8 N), subjects rated the experimental pain using a visual analog scale.Results: Significant results were only found with an exposure time of 60 min and a stamp pressure of 0.8 N. At a concentration of 20%, lidocaine was more effective compared to placebo and equally effective compared to lidocaine/prilocaine in controlling pain. The analgesic effect of the cream containing lidocaine 10% and additional trometamol was significantly superior to that of placebo and non-inferior to that of lidocaine/prilocaine. In this study, the penetration enhancer propylene glycol did not accelerate the onset of the analgesic effect. In contrast, the addition of trometamol (Tris/THAM) accelerated the onset of the effect compared to the native formulation (at 0.4 and 0.8 N). In all of the adult subjects of this study, the minimum exposure time was 60 min for any of the tested topical anesthetic creams.Conclusion: The results of this study indicate that a cream containing 20% lidocaine, 38% trometamol and 10% propylene glycol may be used as an alternative to lidocaine/prilocaine with a comparable effect and without the need to extend exposure time. Keywords: local anesthetics, topical anesthesia, EMLA®, topical anesthetic cream, lidocaine, prilocaine