Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Does spinal anesthesia result in a more complete sympathetic block than that from epidural anesthesia?
Spinal and epidural injection of local anesthetics are used to produce sympathetic block to diagnose and treat certain chronic pain syndromes. It is not clear whether either form of regional anesthesia produces a complete sympathetic block. Spinal anesthesia using tetracaine has been reported to produce a decrease in plasma catecholamine concentrations. This has not been demonstrated for epidural anesthesia in humans with level of anesthesia below C8. One possible explanation is that spinal anesthesia results in a more complete sympathetic block than epidural anesthesia. To examine this question, a cross-over study was performed in young, healthy volunteers. ⋯ Spinal anesthesia did not result in a more complete attenuation of the sympathetic response to a CPT than did epidural anesthesia. In response to the CPT, spinal anesthesia blocked the increase in cardiac index, and epidural anesthesia resulted in a decrease in total peripheral resistance compared to the pre-anesthesia state. The differences between the techniques are not significant and are of uncertain clinical implications.
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Randomized Controlled Trial Comparative Study Clinical Trial
Cervical spine movement during laryngoscopy with the Bullard, Macintosh, and Miller laryngoscopes.
Direct laryngoscopy requires movement of the head, neck, and cervical spine. Spine movement may be limited for anatomic reasons or because of cervical spine injury. The Bullard laryngoscope, a rigid fiberoptic laryngoscope, may cause less neck flexion and head extension than conventional laryngoscopes. The purpose of this study was to compare head extension (measured externally), cervical spine extension (measured radiographically), and laryngeal view obtained with the Bullard, Macintosh, and Miller laryngoscopes. ⋯ The Bullard laryngoscope caused less head extension and cervical spine extension than conventional laryngoscopes and resulted in a better view. It may be useful in care of patients in whom cervical spine movement is limited or undesirable.
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Multicenter Study Clinical Trial
Postoperative apnea in former preterm infants after inguinal herniorrhaphy. A combined analysis.
Controversy exists as to the risk for postoperative apnea in former preterm infants. The conclusions of published studies are limited by the small number of patients. ⋯ The analysis suggests that, if it is assumed that the statistical models used are equally valid over the full range of ages considered and that the average rate of apnea reported across the studies analyzed is accurate and representative of actual rates in all institutions, the probability of apnea in nonanemic infants free of recovery-room apnea is not less than 5%, with 95% statistical confidence until postconceptual age was 48 weeks with gestational age 35 weeks. This risk is not less than 1%, with 95% statistical confidence, for that same subset of infants, until postconceptual age was 56 weeks with gestational age 32 weeks or postconceptual age was 54 weeks and gestational age 35 weeks. Older infants with apnea in the recovery room or anemia also should be admitted and monitored. The data do not allow prediction with confidence up to what age this precaution should continue to be taken for infants with anemia. The data were insufficient to allow recommendations regarding how long infants should be observed in recovery. There is additional uncertainty in the results due to the dramatically different rates of detected apnea in different institutions, which appear to be related to the use of different monitoring devices. Given the limitations of this combined analysis, each physician and institution must decide what is an acceptable risk for postoperative apnea.
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The analgesic and sedative-hypnotic utility of the alpha 2 agonists clonidine and dexmedetomidine are currently being investigated. Both compounds exert their behavioral responses by activating central alpha 2 adrenoceptors, albeit with different selectivities and efficacies. Furthermore, the analgesic and hypnotic behavioral responses are produced at different sites and may be affected independently of one another. A series of studies was conducted in rats to determine (1) whether tolerance and cross-tolerance develop to the analgesic actions of clonidine or dexmedetomidine; (2) how the number of available alpha 2 adrenoceptors affects the analgesic response to dexmedetomidine and clonidine; and (3) how the number of available alpha 2 adrenoceptor affects the hypnotic response to dexmedetomidine. ⋯ Fewer alpha 2 adrenoceptors need to be available for analgesia to be produced by dexmedetomidine compared with the number required for analgesia by clonidine. This difference should result in less tolerance in the analgesic response to dexmedetomidine than to clonidine with chronic use. Dexmedetomidine requires fewer alpha 2 adrenoceptors to elicit an analgesic response than it does to elicit a hypnotic response. Thus the analgesic properties of alpha 2-adrenergic agonists persist after the hypnotic response has been attenuated after chronic alpha 2 agonist administration.
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Comparative Study Clinical Trial
Weekly ventilator circuit changes. A strategy to reduce costs without affecting pneumonia rates.
Mechanical ventilator circuits are commonly changed at 48-h intervals. This frequency may be unnecessary because ventilator-associated pneumonia often results from aspiration of pharyngeal secretions and not from the ventilator circuit. We compared the ventilator-associated pneumonia rates and costs associated with 48-h and 7-day circuit changes. ⋯ We found no difference in pneumonia rates with ventilator circuit changes at 48-h and 7-day intervals. Ventilator circuits can be safely changed at weekly intervals, resulting in large cost savings.