Anesthesia and analgesia
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Anesthesia and analgesia · Jul 2003
Comparative StudyProcaine and mepivacaine have less toxicity in vitro than other clinically used local anesthetics.
The neurotoxicity of local anesthetics can be demonstrated in vitro by the collapse of growth cones and neurites in cultured neurons. We compared the neurotoxicity of procaine, mepivacaine, ropivacaine, bupivacaine, lidocaine, tetracaine, and dibucaine by using cultured neurons from the freshwater snail Lymnaea stagnalis. A solution of local anesthetics was added to the culture dish to make final concentrations ranging from 1 x 10(-6) to 2 x 10(-2) M. Morphological changes in the growth cones and neurites were observed and graded 1 (moderate) or 2 (severe). The median concentrations yielding a score of 1 were 5 x 10(-4) M for procaine, 5 x 10(-4) M for mepivacaine, 2 x 10(-4) M for ropivacaine, 2 x 10(-4) M for bupivacaine, 1 x 10(-4) M for lidocaine, 5 x 10(-5) M for tetracaine, and 2 x 10(-5) M for dibucaine. Statistically significant differences (P < 0.05) were observed between mepivacaine and ropivacaine, bupivacaine and lidocaine, lidocaine and tetracaine, and tetracaine and dibucaine. The order of neurotoxicity was procaine = mepivacaine < ropivacaine = bupivacaine < lidocaine < tetracaine < dibucaine. Although lidocaine is more toxic than bupivacaine and ropivacaine, mepivacaine, which has a similar pharmacological effect to lidocaine, has the least-adverse effects on cone growth among clinically used local anesthetics. ⋯ Systematic comparison was assessed morphologically in growth cones and neurites exposed to seven local anesthetics. The order of neurotoxicity was procaine = mepivacaine < ropivacaine = bupivacaine < lidocaine < tetracaine < dibucaine. Although lidocaine is more toxic than bupivacaine and ropivacaine, mepivacaine, which has a similar pharmacological effect to lidocaine, is the safest among clinically used local anesthetics.
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Anesthesia and analgesia · Jul 2003
Case ReportsSpinal anesthesia for cesarean delivery in a woman with a surgically corrected type I Arnold Chiari malformation.
We report the successful management and outcome of spinal anesthesia for Cesarean delivery in a woman with a surgically corrected Arnold Chiari Type 1 malformation, a seizure disorder, and idiopathic thrombocytopenia of pregnancy.
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Anesthesia and analgesia · Jul 2003
Isoflurane depresses diffuse noxious inhibitory controls in rats between 0.8 and 1.2 minimum alveolar anesthetic concentration.
Diffuse noxious inhibitory control (DNIC) occurs when the response to a noxious stimulus is inhibited by a second, spatially remote noxious stimulus. The minimum alveolar anesthetic concentration (MAC) to suppress movement is not altered by a second remote noxious stimulus. We hypothesized that DNIC would be depressed in the peri-MAC range. Rats were anesthetized with isoflurane, and MAC was measured. We recorded dorsal horn neuronal responses to noxious thermal stimulation of the hindpaw, with or without concomitant supramaximal noxious mechanical stimulation of the tail or contralateral hindpaw. At 0.8 MAC, the tail clamp decreased neuronal responses 70% compared with control heat-evoked responses (from 1032 +/- 178 impulses per minute to 301 +/- 135 impulses per minute; P < 0.05). The tail clamp had no significant effect on neuronal responses at 1.2 MAC (from 879 +/- 139 impulses per minute to 825 +/- 191 impulses per minute; P > 0.05). Similarly, 1.2 MAC isoflurane significantly depressed DNIC elicited by hindpaw clamping. In another group, the cervical spinal cord was reversibly blocked by cooling to determine whether the inhibition was mediated supraspinally. With spinal cord cooling, the counterstimulus-evoked inhibition was not observed at 0.8 MAC. These results suggest that DNIC involves supraspinal structures and is present at sub-MAC isoflurane concentrations but is depressed at more than 1 MAC. ⋯ Diffuse noxious inhibitory control (DNIC) occurs when a noxious stimulus is perceived as being less painful when a second noxious stimulus is applied elsewhere on the body. DNIC is present in anesthetized animals, although how anesthesia affects it is unknown. We found that isoflurane depressed DNIC in the transition from 0.8 to 1.2 minimum alveolar anesthetic concentration, suggesting that DNIC is depressed in the anesthetic range needed to suppress movement.
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Anesthesia and analgesia · Jul 2003
Intraoperative resource utilization in anesthesia for liver transplantation in the United States: a survey.
Among the intraoperative resources expended for liver transplantation, laboratory tests, personnel, high-flow infusion devices, high-tech monitoring equipment, and veno-venous bypass vary from institution to institution. Although of obvious interest to the anesthesia liver transplantation community and others, little is known regarding current utilization of these resources on a national level. To determine the resource utilization among liver transplantation centers in the United States, we conducted a national survey between April and July 2002. Results were stratified according to pediatric versus adult recipient populations and transplantation case volume. Of 99 centers that received the survey by mail, 66 (66.6%) responded. Pediatric liver transplantation programs were distinctly different in personnel, equipment, monitoring, and veno-venous bypass utilization when compared with adult or mixed-age programs. Among laboratory studies, statistically significant trends emerged for fewer intraoperative determinations of the activated clotting time, magnesium, and phosphate with increasing transplantation volume. The results describe national practice patterns and may be useful for programs to compare their approaches and develop clinical pathways. There is wide variation of resource use between centers. The survey results do not consistently correlate with the few recommendations found in the current literature. ⋯ Currently no comprehensive data are available describing the intraoperative use of laboratory tests, personnel, infusion and perfusion equipment, monitoring technology, and veno-venous bypass by liver transplantation programs. These postal survey results provide an overview of utilization of these resources in anesthesia for liver transplantation.
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For more than a century, Mayo Clinic has used various communication strategies to optimize the efficiency of physicians. Anesthesiology has used colored wooden tabs, colored lights, and, most recently, a distributed video paging system (VPS) that was near the end of its useful life. A computer-based anesthesiology paging system (CAPS) was developed to replace the VPS. The CAPS uses a hands-off paradigm with ubiquitous displays to inform the practice where personnel are needed. The system consists of a dedicated Ethernet network connecting redundant central servers, terminal servers, programmable keypads, and light-emitting diode displays. Commercially available hardware and software tools minimized development and maintenance costs. The CAPS was installed in >200 anesthetizing and support locations. Downtime for the CAPS averaged 0.144 min/day, as compared with 24.2 min/day for the VPS. During installation, neither system was available and the department used beepers for communications. With a beeper, the median response time of an anesthesiologist to a page from a beeper was 2.78 min, and with the CAPS 1.57 min; this difference was statistically significant (P = 0.021, t(67) = 2.36). We conclude that the CAPS is a reliable and efficient paging system that may contribute to the efficiency of the practice. ⋯ Mayo Clinic installed a computer-based anesthesiology paging system (CAPS) to inform operating suite personnel when assistance is needed in procedure and recovery areas. The CAPS is more reliable than the system it replaced. Anesthesiologists arrive at a patient's bedside faster when they are paged with the CAPS than with a beeper.