https://www.annemergmed.com/article/S0196-0644(05)82569-7/pdf

Ketamine sedation for pediatric procedures: Part 2, Review and implications.

Alpha compared to beta adrenergic contributions to dysrhythmias induced by left anterior descending coronary occlusion and by reperfusion were assessed in chloralose-anesthetized cats (n = 96). Alpha receptor blockade with either phentolamine or prazosin significantly reduced the number of premature ventricular complexes during coronary reperfusion (321 +/- 62-14 +/- 10 premature ventricular complexes, P less than 0.001), abolished early ventricular fibrillation (from 25% in controls to 0%), and prevented the increase in idioventricular rate seen with coronary reperfusion. However, beta-receptor blockade was without effect. Ventricular dysrhythmias induced by coronary occlusion alone (without reperfusion) were attenuated markedly by alpha-receptor blockade under conditions in which perfusion (measured with radiolabeled microspheres) within ischemic zones was not affected. Alternative sympatholytic interventions including pretreatment with 6-hydroxydopamine to deplete myocardial norepinephrine from 8.8 +/- 1.4 to 0.83 +/- 0.2 ng/mg protein and render the heart unresponsive to tyramine (120 microgram/kg) attenuated dysrhythmias induced by both coronary occlusion and reperfusion in a fashion identical to that seen with alpha-receptor blockade. Although efferent sympathetic activation induced by left stellate nerve stimulation increased idioventricular rate from 66 +/- 6 to 144+/- 7 beats/min (P less than 0.01) before coronary occlusion, this response was blocked by propranolol but not by phentolamine. In contrast, during reperfusion the increase in idioventricular rate induced by left stellate nerve stimulation (to 203 +/- 14) was not inhibited by propranolol but was abolished by phentolamine (79 +/- 10). Intracoronary methoxamine (0.1 microM) in animals depleted of myocardial catecholamines by 6-hydroxydopamine pretreatment did not affect idioventricular rate before coronary occlusion. However, early after coronary reperfusion, methoxamine increased idioventricular rate from 33 +/- 7 to 123 +/- 21 beats/min (P less than 0.01). Thus, enhanced alpha-adrenergic responsiveness occurs during myocardial ischemia and appears to be primary mediator of the electrophysiological derangements and resulting malignant dysrhythmias induced by catecholamines during myocardial ischemia and reperfusion.

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Alpha adrenergic contributions to dysrhythmia during myocardial ischemia and reperfusion in cats.

The clinical effects and pharmacokinetics of ketamine, administered as an i.v. infusion, were studied in 31 patients. Anaesthesia was induced with ketamine 2 mg kg−1 i.v. and maintained using an i.v. infusion of ketamine, supplemented by nitrous oxide. The plasma concentrations of ketamine, nor-ketamine and dehydro-nor-ketamine were analysed using gas-liquid chromatography. The average maintenance dose of ketamine was 41 ± 21 μg kg−1 min−1, but there was an obvious decrease in the dose required as anaesthesia progressed. This dose gave a stable plasma concentration of ketamine of 9.3 ± 0.8 μmol litre−1. Patients recovered at 2.7 ± 0.9 μmol litre−1. Plasma half-life of ketamine was 79 ±8 min. Maximum concentration of nor-ketamine was 4.7 ± 2.4 μmol litre−1 and of dehydro-nor-ketamine 3.2 ± 1.9 μmol litre−1. There were transient increases (15–30% of pre anaesthetic values) in arterial pressure, heart rate and cardiac output during operation. No postoperative respiratory depression was seen.

Ketamine infusions: pharmacokinetics and clinical effects

UNLABELLED The number of citations an article receives after its publication reflects its recognition in the scientific community. In the present study, therefore, we identified and examined the characteristics of the top 100 most frequently cited articles published in anesthetic journals. These articles were identified using the database of the Science Citation Index Expanded (SCI-EXPANDED, 1945 to present) and the Web of SCIENCE(R). The most-cited article received 707 citations and the least cited article received 197 citations, with a mean of 283 citations per article. These citation classics were published between 1954 and 1997 in 5 high-impact anesthetic journals, led by Anesthesiology (73 articles) followed by Anesthesia & Analgesia (10), British Journal of Anesthesia (10), Anesthesia (6), and Acta Anaesthesiologica Scandinavica (2). Seventy-eight articles were original publications, 22 were review articles, and one was an editorial. They originated from nine countries, with the United States contributing 70 articles. Within the United States, California leads the list of citation classics with 25 articles. Twenty-nine persons authored two or more of the top-cited articles. The main topics covered by the top-cited articles are pharmacology, volatile anesthetics, circulation, regional anesthesia, and lung physiology. This analysis of citation rates allows for the recognition of seminal advances in anesthesia and gives a historic perspective on the scientific progress of this specialty. IMPLICATIONS We performed a citation analysis to identify important contributions and contributors to the anesthetic literature. These classic articles have influenced many people and have brought to our attention the many important advances in anesthesia made during the last 50 yr.

Citation classics in anesthetic journals.

RADITIONAL agents and methods for genT e r a 1 anesthesia have provided effective pain control through total depression of the central nl‘rvous system, including cortical and subcortical regions and various pathways involved in the conduction and perception of affwent impulses in general. Recently, a trend has become apparent toward the selective blocking of pain conduction and perception, leaving those parts of the central nervous system free from the depressant effects of drugs which do not participate in pain transmission and perception.

Keigi Kaya

Papers

Studies of the Mechanism of Cardiovascular Responses to CI-581