Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2005
Review Meta AnalysisRevising a dogma: ketamine for patients with neurological injury?
We evaluated reports of randomized clinical trials in the perioperative and intensive care setting concerning ketamine's effects on the brain in patients with, or at risk for, neurological injury. We also reviewed other studies in humans on the drug's effects on the brain, and reports that examined ketamine in experimental brain injury. In the clinical setting, level II evidence indicates that ketamine does not increase intracranial pressure when used under conditions of controlled ventilation, coadministration of a gamma-aminobutyric acid (GABA) receptor agonist, and without nitrous oxide. Ketamine may thus safely be used in neurologically impaired patients. Compared with other anesthetics or sedatives, level II and III evidence indicates that hemodynamic stimulation induced by ketamine may improve cerebral perfusion; this could make the drug a preferred choice in sedative regimes after brain injury. In the laboratory, ketamine has neuroprotective, and S(+)-ketamine additional neuroregenerative effects, even when administered after onset of a cerebral insult. However, improved outcomes were only reported in studies with brief recovery observation intervals. In developing animals, and in certain brain areas of adult rats without cerebral injury, neurotoxic effects were noted after large-dose ketamine. These were prevented by coadministration of GABA receptor agonists. ⋯ Ketamine can be used safely in neurologically impaired patients under conditions of controlled ventilation, coadministration of a {gamma}-aminobutyric acid receptor agonist, and avoidance of nitrous oxide. Its beneficial circulatory effects and preclinical data demonstrating neuroprotection merit further animal and patient investigation.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Comparative Study Clinical TrialNarcotrend or bispectral index monitoring during desflurane-remifentanil anesthesia: a comparison with a standard practice protocol.
Bispectral Index (BIS) (Aspect Medical Systems, Newton, MA) and Narcotrend (MonitorTechnik, Bad Bramstedt, Germany) are monitoring devices that were, as others, designed to assess the depth of anesthesia. Meanwhile, a number of studies indicate that with total IV anesthesia, BIS and Narcotrend have comparable effects on drug consumption and recovery times whereas comparative clinical data for volatile anesthetics are still missing. Therefore, we designed the present prospective, randomized, and double-blinded study to compare the effects of BIS and Narcotrend monitoring during desflurane-remifentanil anesthesia and versus a standard anesthetic practice protocol. One-hundred-twenty adult patients scheduled for minor orthopedic surgery were randomized to receive a desflurane-remifentanil anesthetic controlled either by Narcotrend or by BIS or solely by clinical variables. Anesthesia was induced with 0.4 microg x kg(-1) x min(-1) remifentanil and 2 mg/kg propofol. After tracheal intubation, remifentanil was infused at a constant rate of 0.2 microg x kg(-1) x min(-1) whereas desflurane in 1.5 L/min O(2)/air was adjusted according to clinical variables or the following target values: during maintenance of anesthesia to a value of "D(0)" (Narcotrend) or "50" (BIS), 15 min before the end of surgery to "C(1)" (Narcotrend) or "60" (BIS), whereas in the standard protocol group, desflurane was controlled according to clinical variables, e.g., heart rate, arterial blood pressure, movements. Recovery times and desflurane consumption were recorded by a blinded investigator. The desflurane vaporizer was weighed before and after anesthesia and consumption per minute was calculated. Data are mean +/- sd. The groups were comparable for demographic data, duration of anesthesia, and mean remifentanil dosages. Compared with standard practice, patients with Narcotrend or BIS monitoring needed significantly less desflurane (standard practice 443 +/- 71 mg/min, Narcotrend 374 +/- 124 mg/min, BIS monitoring 416 +/- 99 mg/min desflurane [both P < 0.05]). However, recovery times were not significantly different between the groups, e.g., opening of eyes 4.7 +/- 2.2 versus 3.7 +/- 2.0 versus 4.2 +/- 2.1 min. During desflurane-remifentanil anesthesia, Narcotrend and BIS monitoring seem to be equally effective compared with standard anesthetic practice: BIS and Narcotrend allow for a small reduction of desflurane consumption whereas recovery times are only slightly reduced. ⋯ Monitoring the electroencephalogram with Narcotrend or Bispectral Index during desflurane-remifentanil anesthesia only slightly reduces recovery times when compared with a standard practice protocol.
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Anesthesia and analgesia · Aug 2005
The gamma-subunit governs the susceptibility of recombinant gamma-aminobutyric acid type A receptors to block by the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6, 2N).
To identify anesthetic effects that produce the different components of the complex anesthetic state, the so-called nonanesthetics/nonimmobilizer classes of compounds have been introduced. Because ionotropic gamma-aminobutyric acid type A (GABA(A)) receptors play an important role in the mediation of the central nervous system (CNS) effects of general anesthetics, and their susceptibility to modulation by various drugs depends on subunit composition, we have compared the effect of the nonimmobilizer 1,2-dichlorohexafluorocyclobutane (F6) on GABA(A) receptors expressed in human embryonic kidney 293 cells transfected with alpha1beta2 versus alpha1beta2gamma2s subunits. Using rapid perfusion and whole-cell recording techniques, we found that, like isoflurane, F6 blocked GABA-induced currents through alpha1beta2 receptors but, unlike isoflurane, the presence of the gamma2s subunit conferred complete resistance to block by F6. Also, in contrast to isoflurane, F6 had no effect on deactivation kinetics of GABA-induced currents in either type of receptor. We conclude that modulation of alphabetagamma receptors plays little or no role in the actions of F6, but the block of alphabeta receptors may contribute to its effects on the CNS. ⋯ Gamma-aminobutyric acidA receptors are the target of numerous drugs affecting the central nervous system. The subunit composition of the GABAA receptors governs their interaction with many drugs. We investigated whether the gamma-subunit influences the interaction with the nonimmobilizer F6.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Comparative Study Clinical TrialIntraarticular patient-controlled regional anesthesia after arthroscopically assisted anterior cruciate ligament reconstruction: ropivacaine/morphine/ketorolac versus ropivacaine/morphine.
Anterior cruciate ligament reconstruction (ACLR) is associated with moderate to severe postoperative pain. We compared the intraarticular analgesic effects of ropivacaine and morphine with or without ketorolac and the need for rescue IV morphine at rest and during movement in patients undergoing anterior cruciate ligament reconstruction during spinal anesthesia. Thirty-nine patients receiving intraarticular patient-controlled regional analgesia with a 10-mL bolus and a 60-min lockout interval were randomized into 3 groups: the RM group received 0.25% ropivacaine and morphine 0.2 mg/mL; the RMK group received 0.25% ropivacaine, morphine 0.2 mg/mL and ketorolac 1 mg/mL; the P group received saline. Analgesic mixtures were prepared in 100-mL bags and coded. If needed, rescue morphine 2 mg was self-administered IV with 10-min lockout intervals. Pain scores and patient satisfaction were assessed at rest and during movement. There were no significant differences among the groups in pain scores and patient satisfaction. Daily morphine consumption was significantly smaller in the RMK group (8 +/- 8 mg) compared with the RM group (23 +/- 20 mg; P = 0.002) and in both groups compared with control (46 +/- 21 mg; P < 0.001). We conclude that intraarticular patient-controlled regional analgesia provides effective pain relief after anterior cruciate ligament reconstruction. The combination of intraarticular ropivacaine, morphine, and ketorolac was superior to control or to a combination of ropivacaine and morphine. ⋯ This study showed the feasibility and efficacy of intraarticular patient-controlled regional analgesia technique for pain relief after anterior cruciate ligament reconstruction. The combination of intraarticular ropivacaine, morphine, and ketorolac was superior to control or to a combination of ropivacaine and morphine.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Comparative Study Clinical TrialA double-blind comparison of intravenous ondansetron and placebo for preventing postoperative emesis in 1- to 24-month-old pediatric patients after surgery under general anesthesia.
We assessed the efficacy and safety of ondansetron (0.1 mg/kg IV) prophylactically administered before surgery for prevention of postoperative vomiting (POV) in a double-blind, placebo-controlled study of 670 pediatric patients, 1- to 24-mo-old, undergoing elective surgery under general anesthesia. The study enrolled 335 children in each treatment group (ondansetron versus placebo). Significantly fewer children treated with ondansetron exhibited emesis or discontinued the study prematurely after surgery (ondansetron, 11%; placebo, 28%; odds ratio = 0.33; P < 0.0001). The number required to treat prophylactically with ondansetron to prevent POV was approximately six. Ondansetron treatment also resulted in fewer patients requiring rescue medication or assumed to have had rescue upon early discontinuation from the study during the postoperative period (ondansetron, 5%; placebo, 10%) and less emesis (0 of 6) after rescue medication when compared with placebo (7 of 21). The incidence of POV and other antiemetic effects of ondansetron were similar in children aged 1-12 mo and 13-24 mo and in children prospectively expected or not expected to require opioids as part of their anesthetic or analgesic management. Ondansetron was well tolerated; the incidence of adverse events considered possibly related to study drug was similar between treatment groups (ondansetron, 1.8%; placebo, 1.5%). ⋯ This prospective, randomized, double-blind, placebo-controlled study establishes the efficacy and tolerability of IV ondansetron (0.1 mg/kg) in the prevention of postoperative emesis in 1- to 24-mo-old pediatric patients undergoing elective surgery under general anesthesia.