Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialPosttetanic potentiation and fade in the response to tetanic and train-of-four stimulation during succinylcholine-induced block.
We designed this study to confirm anecdotal observations that neuromuscular block after a single administration of succinylcholine is characterized by fade to train-of-four (TOF) or tetanic stimulation, as well as posttetanic potentiation. This prospective, randomized, 2-center observational study involved 100 patients. Patients were allocated to 1 of 5 groups and received 0.1, 0.3, 0.5, 0.75, or 1.0 mg/kg succinylcholine during propofol/fentanyl/nitrous oxide anesthesia. Neuromuscular function was monitored by TOF using mechanomyography. At 10%-20% spontaneous recovery of the first twitch of TOF, the mode of stimulation was changed from TOF to 1-Hz single-twitch stimulation followed by a tetanic stimulus (50 Hz) for 5 s. Three seconds later, the single twitch (1 Hz) was applied again for approximately 30 s followed by TOF stimulation until full recovery of the TOF response. Succinylcholine-induced neuromuscular block had the following characteristics: 1) twitch augmentation before twitch depression, which was seen more frequently in patients given smaller doses (0.1 and 0.3 mg/kg) than in those given larger doses (0.5-1.0 mg/kg); 2) TOF fade during onset and recovery of the block; 3) tetanic fade; and 4) and posttetanic potentiation. Posttetanic potentiation was related to the pretetanic twitch height but was not related to the dose of succinylcholine administered. Some characteristics of Phase II block were detectable during onset and recovery from doses of succinylcholine as small as 0.30 mg/kg. Posttetanic potentiation and fade in response to train-of-four and tetanic stimuli are characteristics of neuromuscular block after bolus administration of different doses of succinylcholine. ⋯ Posttetanic potentiation and fade in response to train-of-four and tetanic stimuli are characteristics of neuromuscular block after bolus administration of different doses of succinylcholine. We also conclude that some characteristics of a Phase II block are evident from an initial dose (i.e., as small as 0.3 mg/kg) of succinylcholine.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialModerate-to-severe pain after knee arthroscopy is relieved by intraarticular saline: a randomized controlled trial.
We have previously studied intraarticular (IA) analgesics compared with saline 10 mL in 2 randomized clinical trials. The patients who were given IA saline experienced rapid pain relief. Hypothetically, saline may produce a local analgesic effect by cooling or by diluting IA algogenic substances. This randomized double-blind study compared the analgesic effect of IA saline 10 mL with saline 1 mL, which should be a pure placebo. A soft catheter was left IA in 79 patients. We included 60 patients who developed moderate-to-severe pain within 1 h after knee arthroscopy under general anesthesia. A randomized, double-blind controlled comparison of IA saline 10 mL with saline 1 mL followed. Outcome measures were pain intensity, pain relief, and analgesic consumption. Within 1 h pain intensity decreased in both groups from approximately 50 to approximately 27 on a 0-100 mm visual analog scale. Pain intensity remained low and other pain outcome measures were similar during the 36-h observation period. The patients experienced equally good pain relief after IA injection of saline 10 mL and 1 mL. Our finding of a major placebo effect may have implications for the interpretation of previously published placebo-controlled IA analgesia studies. ⋯ In a randomized controlled trial we showed that pain after knee arthroscopy is modest and short-lived and can successfully be treated with intraarticular saline as placebo.
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Anesthesia and analgesia · Jun 2004
ReviewThe use of intrathecal midazolam in humans: a case study of process.
Early preclinical work demonstrated the potential role of spinal benzodiazepine pharmacology in regulating spinal nociceptive transmission. We review this preclinical activity and the evolving implementation of intrathecal midazolam in humans for pain management. Important elements in this development for use in humans are issues pertinent to safety and the preclinical reports that have increased our understanding of intrathecal midazolam toxicity. We seek to emphasize the time course of these studies and how they merged to provide enabling data that drove the clinical implementation. In the case of midazolam, we point to the potential issues that arose when preclinical safety data were unreasonably ignored and how consideration of preclinical safety data can serve to facilitate drug development by demonstrating reasonable safety profiles that document the minimal degree of potential risk to the patient. Issues that are of continuing relevance to the use of intrathecal midazolam, including issues of formulation and kinetics, are considered. ⋯ The intrathecal use of midazolam has evolved over 20 years though a combination of preclinical and clinical investigations. We review the time course of this development to define critical elements that should be pursued in reducing the risk associated with the clinical use of a novel spinal drug.
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Anesthesia and analgesia · Jun 2004
Comparative StudyIntrathecal midazolam I: a cohort study investigating safety.
Despite conflicting evidence regarding the safety of intrathecal midazolam from animal investigations, its clinical use is increasing. We investigated the potential of intrathecal midazolam to produce symptomatology suggestive of neurological damage. This study compared two cohorts of patients who received intrathecal anesthesia with or without intrathecal midazolam (2 mg). Eighteen risk factors were evaluated with respect to symptoms representing potential neurological complications. The definitions of these symptoms were made wide to maximize the chance of counting patients with neurological sequelae after intrathecal injections. Eleven-hundred patients were followed up prospectively during the first postoperative week by a hospital chart review and 1 mo later by a mailed questionnaire. Symptoms suggestive of neurological impairment, including motor or sensory changes and bladder or bowel dysfunction, were investigated. Intrathecal midazolam was not associated with an increased risk of neurologic symptoms. In contrast, neurologic symptoms were found to be increased by age >70 yr (relative risk, 8.72) and the occurrence of a blood-stained spinal tap (relative risk, 8.07). The administration of intrathecal midazolam, 2 mg, did not increase the occurrence of neurologic or urologic symptoms, as suggested by some preclinical animal experimentation. ⋯ Intrathecal midazolam provides segmental analgesia, but conflicting animal studies have cast doubts on its safety. This investigation studied the effect of intrathecal midazolam by observing two cohorts of patients. In clinical practice, intrathecal midazolam (2 mg) did not increase adverse neurological symptoms compared with conventional therapies.
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Anesthesia and analgesia · Jun 2004
Comparative StudyA comparison of frontal and occipital bispectral index values obtained during neurosurgical procedures.
We placed bispectral index (BIS) sensors on the frontal and occipital areas of neurosurgical patients and compared BIS values obtained from both areas during propofol/fentanyl anesthesia. BIS showed a strong correlation between frontal and occipital montages (r(2) = 0.96; P = 0.03). It may be valid to measure BIS with the sensor on the occipital area if required during frontal neurosurgical procedures. ⋯ Bispectral values were positively correlated when recorded from frontal and occipital sensors in patients undergoing clipping of unruptured cerebral aneurysms while anesthetized with propofol and fentanyl.