Halothane: how should it be used in a developing country?

The anaesthetic agent halothane is still widely used in developing countries including the Islamic Republic of Iran because of its low price. Because of halothane-induced hepatitis, a rare complication, it has been replaced by other inhalation anaesthetics in Western countries; it has been suggested by some Iranian professionals that the Islamic Republic of Iran should do the same. We evaluated various dimensions of this replacement through a literature review to assess the incidence of halothane-induced hepatitis and costs of anaesthetics in the country. We also conducted a questionnaire survey of 30 anaesthesiology/gastroenterology experts about their views on the subject. The results indicate that the incidence of halothane hepatitis in the Islamic Republic of Iran is very low and could mostly be avoided by strict adherence to guidelines. Complete withdrawal of halothane in the Islamic Republic of Iran might not be appropriate at present. Comprehensive cost-effectiveness studies are needed before a decision is made on complete replacement of halothane with other anaesthetics.

[Low flow anaesthesia with isoflurane and sevoflurane in the dog]. / Low-flow-Anästhesie mit Isofluran und Sevofluran beim Hund.

The aim of the present study was to compare the safety and efficacy of sevoflurane and isoflurane during low flow anaesthesia (fresh gas flow (FGF) 14 ml/kg/min) as well as to compare the consumption of both anaesthetics. Data were gathered from 60 dogs assigned for surgery under general anaesthesia with an expected duration of 75 minutes or longer. All dogs were induced with 0.6 mg/kg (maximum 25 mg) l-methadone and 1 mg/kg (maximum 25 mg) diazepam i.v.. Anaesthesia was maintained with isoflurane (group 1) or sevoflurane (group 2) in a mixture with 50% O2 and 50% N2O as carrier gases, under controlled ventilation. Monitoring included electrocardiogram, body temperature, the temperature of in- and exspired gases, arterial oxygen saturation, arterial blood pressure as well as a continuous monitoring of inhaled and exhaled gas concentrations (O2, N2O, CO2, isoflurane, sevoflurane). The consumption of isoflurane and sevoflurane as well as the dogs' recovery times were evaluated for both groups. In all groups the inspired oxygen concentrations ranged above the minimum value of 30 Vol% during low flow anaesthesia, with an arterial oxygen saturation above 97%. End tidal concentration of CO2, heart rate and arterial blood pressure were within the physiological ranges and showed no differences between the two groups. Recovery time was significantly shorter after sevoflurane compared to isoflurane anaesthesia, whilst the consumption of sevoflurane was higher than that of isoflurane. Sevoflurane appears to be as clinically safe as isoflurane in low flow anaesthesia. Even considering that sevoflurane is more expensive than isoflurane, the use of the low flow technique decreases the cost of anaesthesia due to the reduced volatile anaesthetic consumption.

Sevoflurane: are there differences in products?

Sevoflurane is currently available in the United States from two manufacturers: Ultane (Abbott Laboratories, Inc.) and a generic product, Sevoflurane Inhalation Anesthetic (Baxter Healthcare Corp.). These products are rated therapeutically equivalent by the Food and Drug Administration, but there are some differences. Ultane is made in a single-step synthetic process and generic sevoflurane is manufactured using a three-step process. Ultane contains >300 ppm water and generic sevoflurane contains < or =130 ppm water. Ultane is supplied in a plastic polyethylene naphthalate polymer bottle, while generic sevoflurane is supplied in lacquer-lined aluminum bottles. The manufacturing processes and impurities, sevoflurane degradation resulting from Lewis acid reactions, and suitability of nonglass containers for sevoflurane are discussed.

Minimum alveolar concentration of sevoflurane in spontaneously breathing llamas and alpacas.

OBJECTIVE: To determine the minimum alveolar concentration (MAC) of sevoflurane in spontaneously breathing llamas and alpacas. DESIGN: Prospective study. ANIMALS: 6 healthy adult llamas and 6 healthy adult alpacas. PROCEDURE: Anesthesia was induced with sevoflurane delivered with oxygen through a mask. An endotracheal tube was inserted, and a port for continuous measurement of end-tidal and inspired sevoflurane concentrations was placed between the endotracheal tube and the breathing circuit. After equilibration at an end-tidal-to-inspired sevoflurane concentration ratio > 0.90 for 15 minutes, a 50-Hz, 80-mA electrical stimulus was applied to the antebrachium until a response was obtained (ie, gross purposeful movement) or for up to 1 minute. The vaporizer setting was increased or decreased to effect a 10 to 20% change in end-tidal sevoflurane concentration, and equilibration and stimulus were repeated. The MAC was defined as the mean of the lowest end-tidal sevoflurane concentration that prevented a positive response and the highest concentration that allowed a positive response. RESULTS: Mean +/- SD MAC of sevoflurane was 2.29 +/- 0.14% in llamas and 2.33 +/- 0.09% in alpacas. CONCLUSIONS AND CLINICAL RELEVANCE: The MAC of sevoflurane in llamas and alpacas was similar to that reported for other species.

MTBE ambient water quality criteria development: a public/private partnership.

A public/private partnership was established in 1997, under the administrative oversight of the American Petroleum Institute (API), to develop aquatic toxicity data sufficient to calculate ambient water quality criteria for methyl tertiary-butyl ether (MTBE), a gasoline oxygenate. The MTBE Water Quality Criteria Work Group consisted of representatives from private companies, trade associations, and USEPA. Funding was provided by the private entities, while aquatic biological/toxicological expertise was provided by industry and USEPA scientists. This public/private partnership constituted a nonadversarial, cost-effective, and efficient process for generating the toxicity data necessary for deriving freshwater and marine ambient water quality criteria. Existing aquatic toxicity data were evaluated for acceptability, consistent with USEPA guidance, and nineteen freshwater and marine tests were conducted by commercial laboratories as part of this effort to satisfy the federal criteria database requirements. Definitive test data were developed and reported under the oversight of industry study monitors and Good Laboratory Practice standards auditors, and with USEPA scientists participating in advisory and critical review roles. Calculated, preliminary freshwater criteria for acute (Criterion Maximum Concentration) and chronic (Criterion Continuous Concentration) exposure effect protection are 151 and 51 mg MTBE/L, respectively. Calculated, preliminary marine criteria for acute and chronic exposure effect protection are 53 and 18 mg MTBE/L, respectively. These criteria values may be used for surface water quality management purposes, and they indicate that ambient MTBE concentrations documented in U. S. surface waters to date do not constitute a risk to aquatic organisms.

Enflurane in anaesthesiological practice.

Enflurane was given as the principal inhalatory agent in general anaesthesia in 75 patients aged from 17 to 55 years for gynaecological operations. Anaesthesia was conducted with muscle relaxation administering the drug in concentration of 0.2-1% vol. (mean maintenance concentration 0.6%). No cardiovascular, hepatic and renal disturbances were observed. The serum glucose level increased by a mean value of 64.8% during enflurance anaesthesia, however, it did not cross the renal threshold. Enflurane failed to ensure postoperative analgesia. The drug may be used as a valuable supplement to the presently used anaesthetic agents.

[Clinical evaluation of the new anesthetic "Ethrane"]. / Evaluation clinique d'un nouvel agent anesthésique "l'éthrane"

Seventy-four patients aged 14 months to 71 years, classified as ASA I and II were anesthetised with Ethrane for surgical interventions of mean duration 117 minutes. With the exception of 5 patients who were directly anesthetised with Ethrane, the others received Ethrane after induction with Penthiobarbitone. Maintenance of anesthesia was ensured with 1 to 4p. 100 concentrations of Ethrane and 33p. 100 oxygen and 66p. 100 nitrous oxide. Tracheal intubation was facilitated by injection of 1 mg/kg of succinylcholine. Induction with enflurane is rapid with no phenomena of excitation or irritation of the ear passages. The cardiovascular apparatus is stable with no arrythmia but an increase in heart rate of 11 to 50p. 100 is noted and in 41p. 100 of the cases hypotension of 35p. 100 of the intitial value. During spontaneous ventilation, a type of rapid and superficial respiration is observed with a flow volume of 5.3 ml/kg for an average frequency of 25/min. The arterial blood gases show slight hypercapnia. Myorelaxation is significant and better than that obtained with halothane. Coming round poses few problems apart from agitation in adolescents. Response to simple orders appears at 13 minutes. Trembling and rigidity occur in 41p. 100 of the cases for 5 to 30 minutes. From the hepatic point of view, no lastin enzyme changes were noted and no renal toxicity was demonstrated. Ethrane appears to be a good anesthetic agent but the few advantages mentioned means that it does not fulfil ideal conditions.

[The place of enflurane in neuro-anesthesia]. / Place de l'enflurane en neuro-anesthésie

In neuro-anaesthesia, anaesthetic agents must be in accordance with certain criteria necessary to the preservation of the integrity of the brain. Therefore it was in such a perspective that we re-appraised the effects of enflurane upon cortical irritability, metabolism, cerebral blood flow and intracranial pressure. We reached the following conclusions: in normocapnia, and with optimal clinical concentrations, this drug remains the best anaesthetic agent since it has no harmful effect either upon metabolism or upon cerebral blood flow. However, in hypertensive cerebral lesions, caution is called for an it seems advisable to combine Enflurane with mild doses of fentanyl. Finally, anaesthesia with enflurane is followed by a rapid and smooth return to consciousness, a valuable factor in neurosurgery where post-operative neurological watching matters very much.