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Anesthetic Dose (anesthetic + dose)
Selected AbstractsThe role of peripheral Na+ channels in triggering the central excitatory effects of intravenous cocaineEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2006P. Leon Brown Abstract While alterations in dopamine (DA) uptake appear to be a critical mechanism underlying locomotor and reinforcing effects of cocaine (COC), many centrally mediated physiological and affective effects of this drug are resistant to DA receptor blockade and are expressed more quickly following an intravenous (i.v.) injection than expected based on the dynamics of drug concentration in the brain. Because COC is also a potent local anesthetic, its rapid action on Na+ channels may be responsible for triggering these effects. We monitored temperatures in the nucleus accumbens, temporal muscle and skin together with conventional locomotion during a single i.v. injection of COC (1 mg/kg), procaine (PRO, 5 mg/kg; equipotential anesthetic dose), a short-acting local anesthetic drug that, like COC, interacts with Na+ channels, and cocaine methiodide (COC-MET, 1.31 mg/kg, equimolar dose), a quaternary COC derivative that is unable to cross the blood,brain barrier. In this way, we explored not only the importance of Na+ channels in general, but also the importance of central vs. peripheral Na+ channels specifically. COC induced locomotor activation, temperature increase in the brain and muscle, and a biphasic temperature fluctuation in skin. Though PRO did not induce locomotor activation, it mimicked, to a greater degree, the temperature effects of COC. Therefore, Na+ channels appear to be a key substrate for COC-induced temperature fluctuations in the brain and periphery. Similar to PRO, COC-MET had minimal effects on locomotion, but mimicked COC in its ability to increase brain and muscle temperature, and induce transient skin hypothermia. It appears therefore that COC's interaction with peripherally located Na+ channels triggers its central excitatory effects manifested by brain temperature increase, thereby playing a major role in drug sensing and possibly contributing to COC reinforcement. [source] Ventriculo-arterial coupling and mechanical efficiency with remifentanil in patients with coronary artery diseaseACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2004D. Pittarello Background:, Optimum transfer of energy from the left ventricle to the arterial circulation requires appropriate matching of these mechanical systems. Left ventricular-arterial coupling describes this relationship between the ventricular elastance (Ees) and arterial elastance (Ea). The ratio of these elastances defines the efficiency of myocardium and provides in our study a useful technique for assessment of the actions of remifentanil. The purpose of this study was to evaluate the effects of remifentanil on ventriculo-arterial coupling in cardiac surgery in patients with coronary artery disease. Methods:, Fourteen patients with coronary artery disease, submitted intraoperatively to cardiac anesthesia for myocardial revascularization, were examined prospectively. With the use of transesophageal echocardiography (TEE) and different dicrotic arterial pressures, we determined the ventricle elastance (Ees), the arterial elastance (Ea) and myocardial efficiency before and after administration of a slow-bolus of remifentanil (1 µ kg,1). Results:, Remifentanil decreases significantly the ventricular elastance (from 6.09 mmHg ml,1 m,2 to 4.88) (P < 0.05), with a less, but however, significant decrease of arterial elastance (from 3.68 mmHg ml,1 m,2 to 3.13) (P < 0.05). Despite causing simultaneous declines, maintains a good myocardial efficiency (0.64,0.68) with no significant difference. Conclusion:, Although remifentanil depresses ventricular and arterial elastance, preserves a good left ventricular-arterial coupling and mechanical efficiency, despite a little increase of coupling. However, these effects are maintained only during a slow intravenous infusion and are dose-dependent with impairment of coupling, that may contribute to decline in overall cardiovascular performance, at higher anesthetic dose and rapid infusion in patients with a severe myocardial dysfunction. [source] Effects of ketamine on formalin-induced activity in the spinal dorsal horn of spinal cord-transected cats: differences in response to intravenous ketamine administered before and after formalinACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2000H. Nagasaka Background: Although formalin has been widely used as an algesic substance in rodent studies, the unique biphasic effect seen in rats is not present in humans. Humans, like cats, have a monophasic behavioral response to formalin injection. Electrophysiologically, spinal dorsal horn neurons in cats also have what could be considered a monophasic response after the initial burst of activity following formalin injection. Although several studies of the effects of ketamine on formalin responses have been carried out in rodents, we are unaware of similar studies in cats. We hypothesize that such species differences may explain observed differences in preemptive analgesic effects. Therefore, we examined the effects of ketamine on activity of spinal wide dynamic range (WDR) neurons evoked by formalin injection in cats. Methods: We investigated in cats the effect of ketamine on the activity of WDR neurons in the spinal dorsal horn that was evoked by formalin. In addition, we studied the effects of pre- and post-administration of ketamine on the maintained phase of the formalin response. Each dose was a subanesthetic, anesthetic or high anesthetic dose (3.0 mg · kg,1, 10 mg · kg,1, and 30 mg · kg,1). Results: Intravenously administered ketamine produced a dose-dependent depression of evoked activity that was significantly greater when the drug was administered before formalin. Conclusions: In spite of the species differences in responses to formalin, there still appears to be a clear preemptive effect of ketamine in the cat. Species differences may not explain apparent differences between human and animal preemptive analgesia. [source] Intensive care unit management of patients with status epilepticusEPILEPSIA, Issue 2007Thomas P. Bleck Summary The intensive care unit management of status epilepticus focuses on patients who are refractory to initial treatment, who have an underlying condition that require critical care management, or who experience respiratory or cardiovascular complications of their therapies. The available data suggest that failure of a first-line anticonvulsant agent to terminate status should lead to the use of a definitive therapy in general anesthetic doses. Midazolam, propofol, and phenobarbital have been used most frequently; the place of newer agents (e.g., valproate, levetiracetam, or topiramate) remains to be determined. [source] Complete Recovery From Intractable Complex Regional Pain Syndrome, CRPS-Type I, Following Anesthetic Ketamine and MidazolamPAIN PRACTICE, Issue 2 2007Ralph-Thomas Kiefer MD Abstract Objective: To describe the treatment of an intractable complex regional pain syndrome I (CRPS-I) patient with anesthetic doses of ketamine supplemented with midazolam. Methods: A patient presented with a rapidly progressing contiguous spread of CRPS from a severe ligamentous wrist injury. Standard pharmacological and interventional therapy successively failed to halt the spread of CRPS from the wrist to the entire right arm. Her pain was unmanageable with all standard therapy. As a last treatment option, the patient was transferred to the intensive care unit and treated on a compassionate care basis with anesthetic doses of ketamine in gradually increasing (3,5 mg/kg/h) doses in conjunction with midazolam over a period of 5 days. Results: On the second day of the ketamine and midazolam infusion, edema, and discoloration began to resolve and increased spontaneous movement was noted. On day 6, symptoms completely resolved and infusions were tapered. The patient emerged from anesthesia completely free of pain and associated CRPS signs and symptoms. The patient has maintained this complete remission from CRPS for 8 years now. Conclusions: In a patient with severe spreading and refractory CRPS, a complete and long-term remission from CRPS has been obtained utilizing ketamine and midazolam in anesthetic doses. This intensive care procedure has very serious risks but no severe complications occurred. The psychiatric side effects of ketamine were successfully managed with the concomitant use of midazolam and resolved within 1 month of treatment. This case report illustrates the effectiveness and safety of high-dose ketamine in a patient with generalized, refractory CRPS. [source] | ||||||||||