Anesthesia and analgesia
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Anesthesia and analgesia · May 2009
Randomized Controlled Trial Comparative StudyContinuous interscalene brachial plexus block via an ultrasound-guided posterior approach: a randomized, triple-masked, placebo-controlled study.
The posterior approach for placing continuous interscalene catheters has not been studied in a controlled investigation. In this randomized, triple-masked, placebo-controlled study, we tested the hypothesis that an ultrasound-guided continuous posterior interscalene block provides superior postoperative analgesia compared to a single-injection ropivacaine interscalene block after moderately painful shoulder surgery. ⋯ Compared to a single-injection interscalene block, a 2-day continuous posterior interscalene block provides greater pain relief, minimizes supplemental opioid requirements, greatly improves sleep quality, and increases patient satisfaction after moderate-to-severe painful outpatient shoulder surgery.
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Anesthesia and analgesia · May 2009
ReviewOptimal perfusion during cardiopulmonary bypass: an evidence-based approach.
In this review, we summarize the best available evidence to guide the conduct of adult cardiopulmonary bypass (CPB) to achieve "optimal" perfusion. At the present time, there is considerable controversy relating to appropriate management of physiologic variables during CPB. Low-risk patients tolerate mean arterial blood pressures of 50-60 mm Hg without apparent complications, although limited data suggest that higher-risk patients may benefit from mean arterial blood pressures >70 mm Hg. ⋯ Similarly, no distinct clinical benefits have been observed when open venous reservoirs have been compared to closed systems. In conclusion, there are currently limited data upon which to confidently make strong recommendations regarding how to conduct optimal CPB. There is a critical need for randomized trials assessing clinically significant outcomes, particularly in high-risk patients.
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Anesthesia and analgesia · May 2009
Randomized Controlled Trial Comparative StudyDose-dependent suppression of the electrically elicited stapedius reflex by general anesthetics in children undergoing cochlear implant surgery.
Cochlear implants stimulate the auditory nerve to enable hearing. Determining appropriate upper and lower limits of stimulation is essential for successful cochlear implantation. The intraoperative evoked stapedius reflex threshold (ESRT) and evoked compound action potential (ECAP) are commonly used to determine the limits of implant stimulation. In this study, we evaluated the dose-related effects of sevoflurane, desflurane, isoflurane, and propofol on the intraoperative ESRT and ECAP. ⋯ Volatile anesthetics suppress the stapedius reflex in a dose-dependent manner, suggesting that ESRT measurements acquired during volatile anesthesia will overestimate the maximum comfort level, which may cause discomfort postoperatively and adversely affect the child's adaptation to the implant. We advise against the use of volatile anesthetics for measurement of the stapedius reflex threshold during cochlear implant surgery.
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Anesthesia and analgesia · May 2009
Randomized Controlled TrialA combination of electroencephalogram and auditory evoked potentials separates different levels of anesthesia in volunteers.
It has been shown that the combination of electroencephalogram (EEG) and auditory evoked potentials (AEP) allows a good separation of consciousness from unconsciousness. In the present study, we sought a combined EEG/AEP indicator that allows both separation of consciousness from unconsciousness and discrimination among different levels of sedation and hypnosis over a wider range of anesthesia. ⋯ These results show that with the new indicator presented here, a combination of EEG and AEP parameters can be used to differentiate degrees of anesthetic effects over a wide range of hypnosis, from the conscious state to deep anesthesia (i.e., BSP).
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Anesthesia and analgesia · May 2009
ReviewModern rapidly degradable hydroxyethyl starches: current concepts.
Hydroxyethyl starch (HES) is a widely used plasma substitute for correcting perioperative hypovolemia. HES preparations are defined by concentration, molar substitution (MS), mean molecular weight (M(w)), the C(2)/C(6) ratio of substitution, the solvent, and the origin. The possible unwanted side effects of HES are anaphylactic reactions, alterations of hemostasis resulting in increased bleeding, kidney dysfunction, accumulation, and pruritus. ⋯ This review is focused on whether modern (third generation), more rapidly degradable HES preparations with a lower M(w) (130 kD) and a lower MS (<0.5) are safer and have fewer side effects. Several studies demonstrated that such modern HES preparations appear to be safe with regard to hemostasis, kidney function, itching, and accumulation. Modern HES preparations are dissolved in balanced, plasma-adapted solutions that no longer contain unphysiological amounts of sodium and chloride and are thus suitable for correcting hypovolemia.