Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0344307 (analgesia)
 28,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Halothane MAC in dogs was not significantly changed by phenobarbital (PB) therapy. Following 10 consecutive days of oral PB (10 mg/kg), halothane MAC was 0.95 +/- 0.05 vol/dl (mean +/- SE) compared with a halothane MAC of 1.05 +/- 0.03 vol/dl in another group not given PB. The absence of change in MAC may reflect either the development of tolerance to CNS sedative effects of PB or the masking of antanalgesia effects of the barbiturate by associated sedation and/or analgesia.
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PMID:Halothane MAC in dogs unchanged by phenobarbital. 98 22

General anaesthesia is the reversible depression of central nervous system function. There is still no agreement over what constitutes depth of anaesthesia, and the clinical anaesthetist must thus titrate drug input according to clinical signs (heart rate, blood pressure, somatic movement, autonomic responses). The potency of inhalational agents may be expressed in terms of the MAC (minimum alveolar concentration); comparable end-points (including blood concentrations) have been proposed for the intravenous agents. Kinetic infusion regimens can be constructed for the intravenous agents to achieve the ED95 concentrations required to provide clinically adequate anaesthesia. However, because of individual differences in drug kinetics and dynamics, as well as the influences of disease states and intercurrent therapy, the clinician will titrate the dose according to response. Administration of volatile or intravenous anaesthetics by fixed regimens may result in either overdosage or the risk of patient awareness. The choice of anaesthetic drug is usually based on the nonhypnotic side effects of the different agents--including their central and regional cardiovascular effects, the speed and completeness of recovery, and the need to provide intraoperative analgesia. In addition, special techniques and drugs are often needed for neurosurgical, cardiothoracic and obstetric anaesthesia. All anaesthetic agents (inhalation and intravenous) have other side effects (such as cardiorespiratory depression and organ toxicity related to the liver or kidney). Both halothane and enflurane may be responsible for postoperative hepatic dysfunction, while the metabolism of enflurane can also result in nephrotoxicity in patients with pre-existing renal dysfunction. Isoflurane has been reported to cause 'coronary steal' in patients with ischaemic heart disease through its coronary vasodilator properties.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Practical treatment recommendations for the safe use of anaesthetics. 137 60

Transcutaneous cranial electrical stimulation with Limoge's currents has been shown to facilitate anesthesia/analgesia in surgical patients. However, the neurobiologic substrate of this effect remains unknown. The present study was designed to analyze the influence of transcranial electrical stimulation (TCES) on halothane requirements in rats and the contribution of the central endogenous opioid, alpha 2-adrenergic and 5-hydroxytryptamine (5-HT1 and 5-HT2) serotonergic systems to this effect. The influence of TCES on the MAC of halothane (MACH) and its reversibility by a subcutaneous 2 mg/kg naloxone injection were first determined in 20 rats using a randomized blinded protocol. MACH was decreased markedly in stimulated animals (TCES, n = 10) in comparison with sham-operated nonstimulated rats (controls, n = 10): MACH = 0.60 +/- 0.15, mean +/- SD, versus 1.07 +/- 0.05 vol%, P less than 0.001. In TCES animals, naloxone administration restored MACH values to the levels of controls but failed to affect MACH in controls. The influence of the duration of TCES applied prior to MACH determination was further investigated in 30 animals. The magnitude of MACH reduction was significantly increased with the cumulative duration of stimulation. For each duration of stimulation tested, administration of a 5-micrograms intracerebroventricular (icv) dose of the enkephalinase inhibitor thiorphan significantly enhanced TCES effects (P less than 0.05). Finally, the icv administration of a 15-micrograms naloxone dose appeared to reverse completely the MACH reduction elicited by TCES (n = 8, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Transcranial electrical stimulation with Limoge's currents decreases halothane requirements in rats. Evidence for the involvement of endogenous opioids. 173 2

Surgery on the shoulder often causes severe pain and, therefore, requires high doses of opiates. As postoperative pain is frequently treated inadequately, it is desirable to seek alternatives for providing effective analgesia. In a prospective study we examined the efficacy of balanced anesthesia consisting of general anesthesia combined with interscalene brachial plexus blockade for intra- and postoperative analgesia for operations on the shoulder. METHODS. Using the technique described by Winnie, interscalene block (ISB) was performed in 100 awake patients. After location of the brachial plexus by means of a peripheral nerve stimulator, we injected 40 ml bupivacaine 0.375%, after which general anesthesia (GA) was induced. At three predetermined points in time (recovery room, 8 h, and 24 h after the end of surgery), pain was evaluated by a visual analogue scale ranging from 0 to 10 and the extent of sensory blockade was tested by the pinprick method. The results of the pain scores and individual demands for analgesics were compared with a group of 22 patients who received only GA. Both groups were comparable in age, sex, and type of surgical procedure. RESULTS. We noted technical failure of the ISB in 8% of our patients. Side effects such as Horner's syndrome (18%), phrenic nerve paralysis (10%), and recurrent laryngeal nerve block (1%) were only temporarily observed during the action of the local anesthetics. During the surgical procedure, the group with ISB received a mean dose of 0.13 +/- 0.07 mg fentanyl versus 0.29 +/- 0.08 mg in the GA group (P less than 0.01) with equipotent doses of volatile anesthetics (1.0 to 1.5 MAC enflurane). Postoperative pain occurred for the first time in 39% of the patients given ISB later than 12 h after the end of surgery (average 8.7 +/- 5.9 h). In contrast, 95% of the patients with GA complained of pain in the recovery room. Pain measurement by the analogue scale clearly demonstrated the advantages of balanced anesthesia directly and 8 h after the operation (P less than 0.01). Even 24 h after the end of the surgical procedure the patients had better pain relief (P less than 0.05) in spite of the decreasing effect of the ISB. These significant differences led to the following results for postoperative treatment: 35% of the patients with ISB did not require additional analgesics during the first 24-h period after surgery, whereas 95% of those with GA requested analgesia. Only 32% of the ISB patients required opioids versus 86% with GA. The average duration of stay in the recovery room was reduced by 25% in the group with ISB (86 vs 134 min). In a final assessment, 84% of the patients were satisfied with the balanced anesthesia and only 5% were disappointed with the method. CONCLUSION. The combination of ISB and GA allows a reduction in intraoperative doses of opiates and facilitates postoperative pain management. Because of the low incidence of side effects, the lack of complications, and the high degree of patient acceptance, we recommend this type of balanced anesthesia for patients undergoing shoulder surgery.
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PMID:[The combination of general anesthesia and interscalene block in shoulder surgery]. 174 12

Balanced anesthesia is a technique that allows control of blood pressure in patients with coronary artery disease. In order to evaluate the relative requirements of volatile anesthetics during basic opioid analgesia, 51 patients with unimpaired left ventricular function who were undergoing coronary artery bypass grafting during balanced anesthesia were investigated. They were randomly assigned to three groups, i.e. halothane (H), isoflurane (I), and enflurane (E). Permanent medications were maintained up to 12 h preoperatively. After premedication with flunitrazepam, promethazine and piritramide, anesthesia was induced with 7 micrograms/kg fentanyl, 0.3 mg/kg etomidate, and 0.1 mg/kg pancuronium and continued with fentanyl infusion (0.1 microgram/kg-1 min-1). Volatile anesthetics were applied in oxygen/air and adjusted to keep the mean arterial blood pressure within +/- 20% of the preoperative value. End-expiratory concentrations of volatile anesthetics were measured (Capnomac, DATEX) and averaged over time. The mean ages of the patients in the different groups were 60 +/- 7.6 years (H), 59 +/- 7.1 years (I), and 60 +/- 6.9 years (E). Four patients in the halothane group, six in the isoflurane group, and five in the enflurane group took beta-blockers preoperatively. The cumulative doses of fentanyl were: H = 0.80 +/- 0.17 mg, I = 0.85 +/- 0.16 mg, and E = 0.83 +/- 0.16 mg at the time of skin incision and H = 1.20 +/- 0.26 mg, I = 1.38 +/- 0.19 mg, and E = 1.24 +/- 0.25 mg at the beginning of extracorporeal circulation.2+ which are possibly the reason for the high O2-MAC value, which may be abolished during balanced anesthesia. However, both the negative inotropic and the vasodilatory effects of enflurane are more likely explanations for the results. It is concluded that 0.5 to 1.0 MAC of halothane, isoflurane, or enflurane used as equipotent components of balanced anesthesia for blood pressure control during aorto-coronary bypass grafting may differ considerably from the conventional MAC concept.
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PMID:[Mean equipotent blood pressure-lowering concentrations of halothane, isoflurane and enflurane during balanced anesthesia differ from conventional MAC-values]. 175 37

Comparisons between propofol and inhalational anesthetics for maintenance of anesthesia are limited. The purpose of our prospective study was to examine differences between enflurane and propofol during pulmonary resections with one-lung ventilation (1LV). METHOD. 28 patients, ASA risk group II-III, gave written informed consent for inclusion in this institutionally approved study. The patients were randomly allocated to one of the following groups: A: propofol 10 mg kg-1 h-1, B: 1 MAC enflurane, for maintenance of anesthesia. In both groups analgesia was achieved by fentanyl and muscle relaxation, by pancuronium. Ventilation via a double-lumen tube was controlled (FiO2 = 1.0, PaCO2 35-40 mmHg). Measurements, including hemodynamics and arterial and mixed venous blood gases, were obtained before induction (I), during two-lung ventilation (2LV) 15 min after induction in the supine position (II) and 20 min after surgical opening of the chest in the lateral decubitus position (III), 20 min after starting 1LV (IV), and after extubation (V). RESULTS. No significant differences between the two groups were found before induction (I), during 2LV (II, III), or after extubation (V). The only significant differences between the two groups were observed during 1LV (IV): the shunt fraction was 33.9 +/- 2.5% in A and 38.5 +/- 2.6% in B (P less than or equal to 0.05). Hypoxic pulmonary vasoconstriction was not inhibited in A, but was inhibited by 21.5% in group B during 1LV. Since no case of hypoxemia occurred in group A during 1LV (range of PaO2: 75.2-417.0 mmHg), but four patients developed hypoxemia in group B (Range of PaO2: 46.6-431.0 mmHg), regimen A might be of value in high-risk patients during thoracic surgery when 1LV is planned.
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PMID:[A comparison of enflurane and propofol in thoracic surgery]. 200 22

Nitrous oxide (N2O) has been used to produce analgesia and anesthesia for more than 100 yr. However, because of its high MAC value (1.04), general anesthesia with N2O can usually be attained only in a hyperbaric environment. Because of the sparsity of documentation for human physiologic responses to hyperbaric N2O, we studied eight male volunteers at 2 ATA (1520 mm Hg) anesthetized with N2O only for periods of 2-4 h. N2O partial pressures ranged from 836 to 1368 mm Hg. The anesthetic state was associated with tachypnea, tachycardia, increases in systemic blood pressure, mydriasis, diaphoresis, and at times, clonus and opisthotonus. A stable level of physiologic activity was difficult to maintain.
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PMID:Hyperbaric nitrous oxide as a sole anesthetic agent in humans. 230 81

The authors hypothesized that the analgesia provided by intraspinal opiates would decrease anesthetic requirement. To test this hypothesis, 20 women undergoing major gynecologic surgery were divided randomly into two groups. One group received 0.75 mg morphine sulfate intrathecally, and the other, the same dose intramuscularly (control), prior to the induction of anesthesia with halothane. MAC for halothane was 0.81% in the control group and 0.46% in the intrathecal morphine group (P = 0.024). The reduction in anesthetic requirement due to intrathecal morphine is greater than that produced by low to moderate doses of systemically administered opiates.
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PMID:Intrathecal morphine reduces the minimum alveolar concentration of halothane in humans. 284 66

A previous demonstration that the ratio of analgesic to anesthetic endpoints is not constant across inhalation anesthetic agents implies that more than one mechanism of action may be operant in general anesthesia. We hypothesized that the endogenous opiate systems might account for this observed disparity in ratios. The tail flick ED50 (TFED50) in response to a heat stimulus, as an index of analgesia, and MAC as an index of anesthesia, were determined in rats treated with either saline or naloxone, 20 mg/kg, and exposed to halothane, enflurane, or isoflurane. Our findings confirmed those of Deady et al., showing a lack of uniformity of ratios of TFED50/MAC, with values of 0.90 +/- 0.03 for halothane, 0.80 +/- 0.04 for enflurane, and 0.70 +/- 0.04 for isoflurane. Naloxone had no effect on TFED50, MAC, or their ratio. If the endogenous opiate system were involved in the analgesic effect of general anesthetics, naloxone would have affected the ratios. We conclude that opiate systems are not involved in the analgesic action of general anesthetics.
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PMID:Naloxone does not antagonize the analgesic effects of inhalation anesthetics. 300 50

The effects of acupuncture analgesia were studied using the change in halothane MAC in volunteers. Halothane MAC under electrical acupuncture stimulation was reduced to 86.2+/-11.1% from the control value. After naloxone administration the level of the MAC was raised to the control level and the increment was 19.1+/-14.8%. Naloxone itself did not change the halothane MAC in the same subjects. These results suggest that the changes in halothane MAC under acupuncture stimulation are caused by the release of an endogenous analgesic substance in the brain.
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PMID:Antagonism of acupuncture analgesia by naloxone in unconscious man. 693 Mar 31


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