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 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many plastic surgery procedures that have traditionally been performed under general endotracheal anesthesia may safely be undertaken using a ketamine-based intravenous sedation technique. General endotracheal anesthesia has many drawbacks, including lack of patient acceptance. Ketamine-based intravenous sedation technique includes the following steps: 1. The patient is placed in a dissociated state using sedative and narcotic agents accompanied by a subanesthetic dose (0.5 mg/kg) of ketamine. 2. A dilute local anesthetic solution (0.25% lidocaine with 1:2,000,000 epinephrine) is infiltrated into the involved tissues to provide anesthesia and hemostasis. 3. The patient is maintained in a tranquil state throughout the procedure by periodic titration of additional doses of sedative and narcotic agents. Advantages of the technique include reducing the need for intubation and its associated hazards, dramatically decreased blood loss due to use of dilute epinephrine solution, reduced recovery time, ability of patients to respond to commands during surgery, avoidance of positioning injuries and increased rapport between patient, surgeon and anesthetist. Disadvantages include respiratory depression and potential for hypoxia. Dissociative intravenous sedation combined with dilute local anesthetic provides a useful addition to the anesthetist's armamentarium.
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PMID:Reducing the need for intubation in plastic surgery. 189 65

Propofol (Diprivan), a modern intravenous hypnotic, produces a reduction in both cardiac index (CI) and mean arterial pressure (MAP). Ketamine (Ketanest), a potent analgesic, in contrast, causes an increase in MAP and CI. The aim of the present study was to investigate whether the combination of propofol and ketamine can give better hemodynamic stability during the induction and maintenance of general anesthesia than propofol used with fentanyl, whose cardiodepressant actions may cumulate. METHODS. For induction of general anesthesia 10 patients (ASA I and II) each received 3-5 boluses of propofol (0.5 mg.kg-1 during 35 s until predetermined level of anesthesia was reached (stage D2/E0 according to [20]) followed by a continuous propofol infusion (0.120 mg.kg-1.min). Fentanyl 0.1 mg was administered to each patient in group A for induction of anesthesia and again if evident pain was present. In group B ketamine was given following a pharmacokinetic model based on computer-simulated calculation. After an initial bolus of 38 mg injected within 2 min further doses of 42 mg, 35 mg, 32 mg and 28 mg ketamine were administered over 30 min at a time. Signs of evident pain were treated by means of supplementary doses of 0.5 mg.kg-1. RESULTS. In both groups a moderate drop of MAP was observed after the induction of general anesthesia. Two patients in each group showed a distinct decrease in MAP (-32%). The heart rate dropped slightly (-9%) in group A, but did not change in group B. Following intubation the MAP rose by less in group A (+8%) than in group B (+21%). After the beginning of the operation the group treated with propofol/fentanyl showed major hemodynamic changes; in particular, bradycardia with less than 40 bpm was observed in more patients than in the propofol/ketamine group. Postoperatively, fewer patients in group B required rescue doses of analgesics (1 of 10) than these in group A (7 of 10), though vigilance was better in group B. DISCUSSION. The dose of ketamine administered during the induction of general anesthesia may have been not high enough to neutralize the cardiodepressant effect of propofol. But during the maintenance of anesthesia there was in fact better hemodynamic stability in group B than in group A as a result of the neutralization of opposing actions. Fentanyl even intensified the fall in MAP after propofol. Patients in group B showed better vigilance as well as better pain relief postoperatively. The population of the fentanyl group was obviously more deeply sedated and analgesia was still inadequate. In our study general intravenous anesthesia with propofol and ketamine offered the advantages of better analgesia, a higher state of vigilance and the absence of respiratory depression during the postoperative phase compared with the combination of propofol and fentanyl.
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PMID:[The effect of propofol-ketamine anesthesia on hemodynamics and analgesia in comparison with propofol-fentanyl]. 207 45

1. To assess the direct spinal contributions to the depression of reflexes caused by general anaesthetics, the intravenous potency of four injectable anaesthetics has been compared in two preparations: in decerebrate, spinalised rats, using a novel preparation requiring little surgical intervention, and in intact rats with chronically implanted i.v. cannulae. 2. Methohexitone (1-8 mg kg-1 i.v.), alphaxalone/alphadolone (0.5-8 mg kg-1 i.v.), alpha-chloralose (20-80 mg kg-1 i.v.) and ketamine (0.5-16 mg kg-1 i.v.) all produced a dose-dependent depression of single motor unit activity evoked by controlled noxious mechanical stimuli in decerebrate, spinalised animals. 3. The sedative and motor effects brought about by equivalent doses to those used in the electrophysiological experiments were assessed in intact rats. Methohexitone, alphaxalone/alphadolone and alpha-chloralose all caused similar levels of behavioural sedation at the doses that caused depression of spinal reflexes. Ketamine required relatively much higher doses to cause sedation. 4. To determine whether background anaesthesia modulated the potency with which these compounds affected spinal reflex activity, depressant effects in decerebrate, unanaesthetized rats were compared with those in animals maintained under anaesthesia with either alpha-chloralose or the steroid mixture of alphaxalone/alphadolone. The presence of either of these two agents as maintenance anaesthetics did not influence the effectiveness with which other compounds depressed nociceptive responses. However, additional doses of the maintenance anaesthetics were less effective than the same doses tested in decerebrate animals. 5. All the anaesthetics tested produced a significant depression of spinal reflex responses to noxious stimuli at doses well below those required for anaesthesia. Whilst the presence of maintenance anaesthetics appears not to distort pharmacological tests of other agents, there may nonetheless be a biasing of the samples of cells recorded.
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PMID:Spinal effects of four injectable anaesthetics on nociceptive reflexes in rats: a comparison of electrophysiological and behavioural measurements. 207 76

The cardiopulmonary consequences of hemorrhagic hypovolemia and the subsequent administration of ketamine were evaluated in eight dogs; five additional dogs served as controls. Heart rate (HR), systemic vascular resistance, breathing rate, minute ventilation (VE), PaO2, alveolar-arterial oxygen tension gradient, and oxygen extraction ratio increased, while arterial and pulmonary pressures, CVP, cardiac output, oxygen transport, PVO2 PaCO2, mixed venous oxygen content, bicarbonate, and base deficit decreased in response to hypovolemia. Ketamine administration was associated with a significant increase in HR, arterial and pulmonary BP, and PaCO2, and a significant decrease in VE (transient), PaO2 (transient), and pH. Ketamine supported cardiovascular function well, did not impair tissue oxygenation, and caused only transient respiratory depression in these hypovolemic dogs.
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PMID:Ketamine in hypovolemic dogs. 211 56

Ketamine produces rapid and consistent pediatric sedation with a predictable onset and recovery time. A wide margin of safety is afforded without the respiratory and cardiovascular depression commonly seen with alternative agents. The efficacy of ketamine is well established in anesthesia and dentistry and has extensive applications in other specialties. Ketamine sedation facilitates superior technical and cosmetic results while minimizing emotional trauma to distraught children. The much-feared complications of aspiration and laryngospasm are extremely rare when ketamine is used with proper precautions. Ketamine deserves increased use in the ED, and we advocate additional clinical investigation in this setting.
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PMID:Ketamine sedation for pediatric procedures: Part 2, Review and implications. 220 90

Ketamine was used as the sole anaesthetic during the induction-to-delivery interval in 20 full-term patients undergoing elective Caesarean section. The intravenous administration of ketamine 1.5 mg.kg-1 was followed by succinylcholine 1.5 mg.kg-1 and tracheal intubation. The mother's lungs were then ventilated using 100 per cent oxygen until the baby was delivered. Intraoperative maternal awareness was assessed by the isolated forearm technique. The Apgar scores of the newborn at one and five minutes, as well as their umbilical vein blood gases were also evaluated and correlated with the induction-to-delivery (I-D) and the uterine incision-to-delivery (U-D) intervals. In 13 patients (Group A) the I-D interval was less than 10 min and U-D interval less than 90 sec, while in seven (Group B) the I-D interval was greater than or equal to 10 min and the U-D interval greater than or equal to 90 sec. The isolated arm test was negative in all patients having an I-D interval less than 10 min, and was positive in three patients when the I-D interval exceeded ten minutes. The newborns of group A showed higher Apgar scores at one minute, as well as higher umbilical vein PO2 than was achieved in Group B. It was concluded that the technique used was not associated with maternal awareness or neonatal depression, provided that the I-D interval was less than 10 min and the U-D interval was less than 90 sec.
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PMID:Maternal awareness and neonatal outcome after ketamine induction of anaesthesia for Caesarean section. 220 34

The effects of the dissociative anaesthetic, ketamine on GABA-evoked changes in the excitability of myelinated fibers of dorsal and ventral roots of isolated bullfrog sciatic nerves were examined. Ketamine alone (0.01-1000 microM) evoked small increases (less than 5%) in dorsal root fiber excitability, as reflected in the half-maximal A-fiber compound action potential when concentrations were greater than 10 microM; with greater than or equal to 0.1 microM even larger increases (greater than or equal to 10%) were elicited in the ventral root fibers. As well, the increases evoked by greater than or equal to 10 microM ketamine were followed by graded decreases. 0.1 and 10 microM ketamine, concentrations which by themselves had small or no effect, produced a dose-dependent depression of the large increases in excitability which are induced by activation of GABA receptors. In the presence of ketamine GABA concentration-response curves of the dorsal root fibers showed depression of the maximal response, while those of the ventral root fibers were shifted to the right. This apparent antagonism of GABA responses by ketamine may arise from blockade of receptor-mediated effects (e.g. K+/Cl- currents and/or secondary depolarization from K+ accumulation), but could also be caused by a selective potentiation of hyperpolarizing receptors.
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PMID:Effects of ketamine on GABA-evoked excitability of peripheral nerve. 231 96

MK-801 is a ligand at phencyclidine recognition sites associated with NMDA-coupled cation channels, where it acts as a potent noncompetitive antagonist of central glutamate/aspartate (NMDA-type) receptors. Low doses (10-100 micrograms/kg IP) produced a dose-related and prolonged (greater than 1 h) enhancement of variable-interval self-stimulation responding. Higher doses (300 micrograms/kg) caused flaccid ataxia and disrupted responding. Ketamine HCl (3.0-100 mg/kg IP), a dissociative anaesthetic binding to the phencyclidine site, produced a similar response pattern, but facilitation was less prolonged and occurred over a narrower dose range. Kynurenic acid (3.0-300 mg/kg IP), a nonselective competitive antagonist of glutamate receptors, produced only depression of responding, possibly the result of kynurenate-induced blockade of central kainate and/or quisqualate receptors. The behavioural stimulant effects of MK-801 appear to be an intrinsic and essential feature of selective NMDA antagonists, and these effects of MK-801 differ qualitatively and quantitatively from the well-known facilitatory effects of dopamine-dependent stimulants.
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PMID:The effect of MK-801 and other antagonists of NMDA-type glutamate receptors on brain-stimulation reward. 255 Sep 89

Ketamine has many neuromuscular effects in vitro. Its neuromuscular effects in vivo have been controversial and inconsistent. To systematically examine its neuromuscular effects over a wide dose range and its interaction with all popular nondepolarizing neuromuscular relaxants, the effects of ketamine 2, 5, and 10 mg/kg IV were studied on a continuous but incomplete (50%) neuromuscular block preestablished by an IV infusion of d-tubocurarine, atracurium, vecuronium, and pancuronium. Indirectly stimulated adductor pollicis muscle response of monkeys anesthetized with 0.5-1.0% halothane in oxygen were quantified. Ketamine in the absence of a neuromuscular relaxant had no effect on the thumb twitch. In a dose-dependent manner, ketamine significantly enhanced the 50% depression of the thumb twitch preestablished by a constant IV infusion of each of the four muscle relaxants studied. Ketamine 2 mg/kg potentiated the neuromuscular relaxants in the following order of magnitude: vecuronium greater than atracurium greater than d-tubocurarine greater than pancuronium. However, with a 10 mg/kg dose of ketamine, pancuronium became as potentiated as was vecuronium, i.e., pancuronium = vecuronium greater than atracurium greater than d-tubocurarine. It is concluded that in the primate, ketamine potentiates all nondepolarizing muscle relaxants in a dose-dependent manner.
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PMID:Ketamine potentiates nondepolarizing neuromuscular relaxants in a primate. 256 10

The anaesthesia with Xylazine and Ketamine in 24 foals is described. Special qualities of this form of anaesthesia and dosages for foals of different age are discussed. The combination of Xylazine and Ketamine is well suited for the anaesthesia of foals of all age and risk-groups. The induction takes place quickly and calmly, without signs of cardiorespiratory depression. The maintenance of anaesthesia is possible, without any problem, by repeated injection with Xylazine and Ketamine, as well as by inhalation anaesthesia with volatile anaesthetics. The recovery is short; the animals rise swiftly and safely. For these reasons we prefer, in foals, the anaesthesia with Xylazine and Ketamine to the induction and maintenance of anaesthesia with thiobarbiturates.
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PMID:[Anesthesia of horses with xylazine and ketamine. 1. Anesthesia of foals]. 261 26


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