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At least 127 records · Page 7Linked to original sources
PubMed1995

Comparison of tribromoethanol, ketamine/acetylpromazine, Telazol/xylazine, pentobarbital, and methoxyflurane anesthesia in HSD:ICR mice.

Variation in the duration of surgical anesthesia in mice prompted an evaluation of various commonly used anesthetics. Using biotelemetric technology, we evaluated the effects of six anesthetic regimens (tribromoethanol, ketamine and acetylpromazine in combination, Telazol and xylazine in two combinations, pentobarbital, and methoxyflurane) on temperature and activity. Six groups of four male HSD:ICR mice received one of the anesthetic regimens or an equivalent volume of saline. Induction time (time from anesthetic administration until righting reflex loss) and duration of anesthesia (loss of response to interdigital toe pinch) were evaluated. Methoxyflurane and both doses of Telazol combinations resulted in the shortest and most repeatable induction times. None of the mice in the ketamine/acetylpromazine- and pentobarbital-treated groups lost the interdigital toe pinch reflex. Duration of anesthesia was superior in the two Telazol/xylazine-treated groups. A direct correlation existed between duration of anesthesia and magnitude and duration of temperature reduction. Duration of anesthesia can be used to predict extent of hypothermia.

Acepromazine↗
PubMed1976

[The influence of methoxyflurane (penthrane) on surface activity of the lung (author's transl)].

Methoxyflurane, at the moment the most potent inhalation anaesthetic, was examined in respect of its surfactant irritating properties in the rabbit. After a five hour anaesthesia with this compound there was, compared with a control group of animals which underwent only mechanical ventilation with room air for the same period, a significant decline of the compliance quotient from 2.99 to 2.55, indicating a relevant impairment of alveolar lining surfactant. A concomitant fall of arterial PaO2 from 84.8 to 71.3 mm Hg showed the resulting deterioration of respiratory function. Postanaesthetic preparations of these lungs examined using the Wilhelmy balance exhibited a significant fall of the stability index from 1.73 to 1.25, though hysteresis remained unaffected. Lung histology showed interstitial edema and patchy atelectasis, features which are found also in the early stages of post-traumatic pulmonary insufficiency. On this basis we recommend that methoxyflurane is not used in patients with impaired surfactant activity as such is found after severe traumatisation, head injury or in special preexisting pulmonary diseases. If this anesthetic is given to healthy individuals, the ventilatory pattern should include periodic sighs and prophylactic PEEP.

Animals↗
PubMed1975

Flecked retina. Appearance secondary to oxalate crystals from methoxyflurane anesthesia.

Calcium oxalate crystals were demonstrated in the retinal pigment epithelium (RPE) of a 66-year old white man with changes in the fundus oculi consistent with the flecked retina ayndrome. The patient had a history of rheumatoid arthritis, mild hypertension, and mild renal insufficiency presumed due to his hypertension. He underwent prolonged abdominal surgery under methoxyflurane anesthesia, following which he developed acute irreversible renal failure. Calcium oxalate crystals were demonstrated postoperatively in a kidney biopsy specimen. He subsequently was maintained on renal dialysis with decreasing renal function. Several weeks before his death fundus examination revealed a picture suggestive of a flecked retina syndrome. At autopsy, widespread oxalosis was found including crystals in the RPE and in some areas in the neural retina and cillary epithelium.

Acute Kidney Injury↗
PubMed1985

Reference values of the brainstem auditory evoked response of methoxyflurane anesthetized and unanesthetized dogs.

The brainstem auditory evoked response (BAER) was recorded from 7 unanesthetized and 27 methoxyflurane anesthetized dogs. A 0.1 msec, 70 dB stimulus delivered at 10 Hz evoked the expected seven wave BAER. Mean peak wave latencies and standard deviations were calculated. Differences were not found between neither right and left ears, nor male and female dogs. The anesthetized dogs had a significantly longer latency for all waves, except wave I, than the unanesthetized dogs. Use of the BAER as a diagnostic technique for brainstem lesions is recommended.

Anesthesia↗
PubMed1992

Advantages and guidelines for using methoxyflurane.

Methoxyflurane anesthesia is particularly useful for orthopedic surgery (muscle relaxation, analgesia, and slow recovery), ophthalmic surgery (central eye position), and small laboratory animals (high therapeutic index and slow induction).

Anesthesia, Inhalation↗
PubMed1999

Effects of methoxyflurane anesthesia on the pharmacokinetics of 125I-IAZA in Sprague-Dawley rats.

Effects of methoxyflurane anesthesia on the pharmacokinetics of intravenous 125I-IAZA in rats are reported. No significant differences in t(1/2alpha), t(1/2beta), V(SS), and ClTB for total radioactivity (125I-IAZA and metabolites) were observed between the anesthetized (Group 1, n = 4) and nonanesthetized (Group 2, n = 3) animals. For 125I-IAZA, ClTB increased from 646 +/- 52 mL/h/kg to 2250 +/- 351 mL/h/kg and t(1/2beta) decreased from 97.7 +/- 17.5 min to 35.6 +/- 5.4 min, for Groups 1 and 2, respectively. There were no differences in V(SS) or t(1/2alpha) between the two groups. These findings support literature reports of anesthetic effects on xenobiotic pharmacokinetics, and indicate a need for caution in the evaluation of preclinical imaging studies in which animals are immobilized with anesthetics.

Anesthesia, Inhalation↗
PubMed1979

Pollution of delivery ward air by nitrous oxide--methoxyflurane.

Pollution of delivery ward atmosphere by analgesic gases and vapors has not been studied as extensively as pollution of operating theaters. This study shows that delivery room atmosphere is polluted by methoxyflurane (0.5--0.8 ppm) and nitrous oxide (300--540 ppm) and that a local gas exhaust system reduces the concentration by half.

Air Pollutants↗
PubMed1975

Metabolism in vitro of enflurane, isoflurane, and methoxyflurane.

Specific activities of enflurane, isoflurane, and methoxyflurane defluorinases were measured in microsomes prepared from the livers of Fischer 344 rats; the ratio of these activities was 23:3:1. Pretreatment with phenobarbital significantly increased the defluorinase activities of all three agents. Factors that influence anesthetic drug metabolism are discussed; tissue solubility is considered to be the most important.

Anesthesia, Inhalation↗
PubMed1978

Fetotoxicity in rats following chronic exposure to halothane, nitrous oxide, or methoxyflurane.

An animal model was used to investigate the comparative fetal toxicities of three inhalational anesthetics. Pregnant Sprague-Dawley rats were exposed for eight hours a day throughout the 21 days of gestation to graded concentrations of halothane (0.16-0.32 per cent), or nitrous oxide (1-50 per cent), or a nitrous oxide (10 per cent) and halothane (0.16 per cent) mixture, or methoxyflurane (0.01-0.08 per cent). High subanesthetic concentrations of all the inhalational anesthetics could cause fetal growth retardation (e.g., 3-21 per cent decreases in normal fetal weights), but this was unaccompanied by significant fetal loss (overall rate: 4.8 +/- 1.2 per cent, mean +/- SE, in anesthetic groups) or any evidence of skeletal or gross abnormalities related to treatment. It is concluded that these rodent studies do not implicate any specific inhalational anesthetic agent in fetal toxicity, and that the effects of additional factors, such as stress, must be considered.

Animals↗
PubMed1982

Densities of liquid halothane, methoxyflurane, and enflurane between 0 degrees and 35 degrees C.

The authors determined the densities of liquid halothane, methoxyflurane, and enflurane over the temperature range of 0 to 35 degrees C. The measurements were undertaken because detailed information of this type is useful in, for example, the preparations of chromatography standards, and no previous comparable study has been published. The densities of the liquid agents at different temperatures were described by regression equations. Calculated values using these equations compared favorably with isolated values reported in the literature.

Chemical Phenomena↗
PubMed1977

Methoxyflurane hepatitis.

A veterinarian's assistant who sniffed methoxyflurane as a euphoriant developed fulminant hepatitis and died of hepatic failure. The abuse of fluorinated anesthetics has been reported and may be more frequent than is commonly believed. It is suggested that fluorinated anesthetics should be considered as a causative agent in a case of fulminant hepatitis, especially in patients who have easy access to such drugs.

Adult↗
PubMed1989

Blood gas tensions, acid-base status and cardiovascular function in miniature swine anaesthetized with halothane and methoxyflurane or intravenous metomidate hydrochloride.

Göttingen mini-pigs were given atropine and anaesthetized with one of the following drug combinations: 1) azaperone + metomidate, 2) acepromazine + thiopentone for endotracheal intubation, followed by halothane + methoxyflurane in oxygen. Respiration rate, arterial O2 and CO2 tensions, arterial pH, mean arterial blood pressure and heart rate were recorded at 15 min. intervals from 30 to 120 min. after the induction of anaesthesia. The azaperone-metomidate combination, which requires continuous intravenous access, caused a mild respiratory acidosis, but acid-base status was stable, whereas blood pressure and heart rate rose steadily throughout the observation period. The second combination depressed respiratory and cardiovascular function, but the condition of the animals did not deteriorate further during 2 hrs of surgical anaesthesia. Endotracheal intubation for inhalation anaesthesia should, however, be performed after a single injection of metomidate, as thiopentone tended to cause respiratory arrest.

Acid-Base Equilibrium↗
PubMed1975

A new method of closed circuit anaesthesia utilising halothane and methoxyflurane.

Experiences with a new technique of closed circuit anaesthesia used for 1003 surgical cases involving cats and dogs are described. The technique utilises the combined vapors of methoxyflurane and halothane from dual, low-resistance vaporisers situated in series, and supported by low flow rates of 100% oxygen in the inspiratory limb of the anaesthetic machine. This anaesthetic circuit can be adapted for many surgical procedures involving both controlled and spontaneous ventilation techniques and for young and old animals. The technique is considered safe, economical and easily managed and pollution of the operating theatre is eliminated by the use of the completely closed circuit.

Anesthesia, Inhalation↗
PubMed1989

Anaesthetic concentrations of enflurane and methoxyflurane in rat brain in-vivo and in-vitro.

We measured concentrations of enflurane and methoxyflurane in brains of anaesthetized rats and established conditions for reproducing these concentrations in brain tissue in-vitro. Despite a 12-fold difference in inspired potency, brain concentrations resulting in anaesthesia were similar for both compounds. However, substantially lower concentrations in the equilibrating gas were necessary to achieve similar tissue concentrations in-vitro, probably because anaesthetic-induced respiratory depression or changes in cardiac output causes incomplete equilibration in-vivo. These studies provide direct evidence that brain concentrations associated with anaesthesia are similar for anaesthetics with different inspired potencies. They also suggest that lower concentrations in the equilibrating gas should be used in-vitro to reproduce clinically relevant tissue concentrations that are necessary to cause anaesthesia in-vivo.

Anesthesia, General↗
PubMed1987

Cardiopulmonary function during 7 h of constant-dose halothane and methoxyflurane.

Cardiopulmonary effects of prolonged, constant-alveolar-dose halothane (HAL) and methoxyflurane (MOF) in O2 anesthesia on spontaneously breathing dogs were determined. One hour after anesthetic induction, end-tidal concentration was set at 1.04% HAL or 0.28% MOF [each representing 1.2 minimum alveolar concentration (MAC) for dogs] and maintained for 7 h. No time-related changes were associated with MOF. However, HAL significantly (P less than 0.05) elevated cardiac output (Q) from 2 to 7 h by increasing stroke volume; mean aortic pressure (MAP) also increased with time (P less than 0.05 beginning at 5 h). Four of these dogs were studied again at least 3 wk later at a constant end-tidal dose of 1.48% HAL in O2 (1.7 MAC). Q and MAP were lower initially during 1.7 MAC than during 1.2 MAC but not after 2 h of anesthesia. The greater HAL dose initially depressed ventilation and elevated arterial partial pressure of CO2 (PaCO2) compared with the lower dose. PaCO2 continued to increase with duration of 1.7 MAC HAL, as did results of ventilatory gas volume and flow measurements.

Animals↗
PubMed1980

Halothane, enflurane, methoxyflurane, and isolated human uterine muscle.

The depressant effects of halothane, enflurane and methoxyflurane at 0.5, 1.0 and 1.5 MAC on isolated human gravid uterine muscle have been studied. The muscle samples were obtained from women undergoing caesarean section at between 38 and 41 weeks gestation. All three agents produced depression of uterine muscle contractility and of contraction frequency. There were no significant differences between the degree of depression of the uterine muscle at equipotent concentrations of the three volatile agents. Differing concentrations of the same agent over the range 0.5 to 1.5 MAC produced no significant change in the uterine muscle depression.

Depression, Chemical↗
PubMed1993

Anesthesia-induced modulation of in vivo antibody levels: a study of pentobarbital, chloral hydrate, methoxyflurane, halothane, and ketamine/xylazine.

The influence of anesthesia on long-term changes in in vivo antibody levels after antigen challenge was examined. Rats experienced a surgical plane of various anesthetics alone (anesthesia/intact) or in combination with laparatomy (anesthesia/laparatomy) and were given 1 or 3 wk to recover. Antigen, keyhole limpet hemocyanin, was then administered, and antibody levels specific to the antigen were measured during the next 14 days. Comparisons were made between anesthesia-treated animals and home cage controls. Pentobarbital and chloral hydrate produced decreases in in vivo antibody levels even 3 wk after exposure, whereas halothane, methoxyflurane, and ketamine/xylazine did not. Ketamine/xylazine produced moderate but not significant decreases in antibody levels when 1 wk intervened between exposure and antigen administration, but not when 3 wk intervened. Surgery did not produce larger changes in antibody levels than did anesthesia itself. These data suggest the possibility that some anesthetics, per se, may contribute to infection that may occur postoperatively.

Anesthetics↗