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Biomedical subjects

M Oikkonen

Publications and source records attributed to M Oikkonen.

29 records · Page 2Linked to original sources
PubMed1989

Cimetidine and ranitidine do not affect enflurane metabolism in surgical patients.

Hepatic cytochrome-P-450-linked microsomal metabolism is inhibited by cimetidine, and to a lesser extent by ranitidine. Such an inhibition might protect against the metabolite-related toxicity of inhalation anesthetics. However, in comparison with the values measured in a control group, neither cimetidine (600 mg p.o. + 200 mg i.m.) nor ranitidine (150 mg p.o. + 50 mg i.m.), both administered 11-12 h before anesthesia, inhibited enflurane metabolism as assessed by the increase in plasma inorganic fluoride concentration and urinary fluoride excretion in 21 ASA I patients anesthetized with enflurane (end-tidal concentration 0.5 +/- 0.05% for 2-6 h). The inorganic fluoride concentration in the gastric juice remained low in all groups.

Aged↗
PubMed1989

Serum fluoride in children anaesthetized with enflurane.

The serum inorganic fluoride concentration (SF) was measured in 40 children aged 22 days to 11 yrs (five infants) undergoing enflurane anaesthesia lasting 20-200 min, at an inspiratory concentration of 0.8 or 1.0%. Regardless of age, SF peaked at 2-8 mumol l-1 after 20-40 min of enflurane exposure, and at 4-10 mumol 1-1 and 6-10 mumol l-1 after 41-90 min and 91-200 min of exposure, respectively. The highest individual value was 12.5 mumol l-1. Another 23 children, aged 1-16 yrs, received 0.8% enflurane for 60 min. The increase in SF was 3-9 mumol l-1, with no clear dependence on age. Altogether, the increase in SF was comparable to that detected in adults after anaesthesia of equal duration.

Aging↗
PubMed1987

Spinal block, after dantrolene pretreatment, for resection of a thigh muscle herniation in a young malignant hyperthermia susceptible man.

We describe a young man who experienced malignant hyperpyrexia, probably triggered by suxamethonium and/or enflurane during his second operation for an epigastric hernia. His malignant hyperthermia susceptibility was later verified using the caffeine/halothane contracture test in vitro. Subsequently, a tumorous mass, consisting of herniated and hypertrophied muscle grew in his thigh, and was resected under spinal anaesthesia. Whereas dantrolene (2.5 mg/kg i.v.) pretreatment produced impaired swallowing, the subsequent high spinal block, in addition, resulted in laboured breathing. It is stressed that respiratory power should be monitored when patients pretreated with dantrolene are given spinal anaesthesia. The muscular symptoms and test results in the patient's relatives are also discussed.

Adolescent↗
PubMed1984

Hepatic metabolic ability during anaesthesia. Evaluation of antipyrine half-lives and their relation to enflurane metabolism.

The antipyrine (phenazone) half-life was determined in 20 surgical patients to discover whether there are changes in hepatic metabolic rate during or immediately after anaesthesia compared with the pre-anaesthetic rate. Nine patients received enflurane (mean duration 8.6, SD 2.0 hours) and six patients had a balanced anaesthetic without enflurane (duration 4.4, SD 3.3 hours). A further five patients received a spinal anaesthetic with bupivacaine. The changes in antipyrine half-life were inconsistent, and there was no evidence of competitive metabolic inhibition by general anaesthesia. Antipyrine half-lives did not correlate with serum fluoride levels or urinary fluoride excretion in the case of enflurane. The mean serum inorganic fluoride concentration rose to 29 mumol/litre, and two patients had potentially nephrotoxic concentrations (64 and 50 mumol/litre) after 8 hours of exposure to enflurane though without any evident harmful effects.

Adolescent↗
PubMed1984

Isoflurane and enflurane in long anaesthesias for plastic microsurgery.

Isoflurane and enflurane as main anaesthetics at 0.5-0.7% end-tidal concentrations in 70% N2O/30% O2 supplemented with fentanyl maintained smooth basal anaesthesia in ASA I-II patients during long (6-11 h) plastic surgery (n = 7 + 6) as well as during shorter (2-4 h) operations (n = 5 + 5). There were no statistically significant differences in haemodynamic parameters between isoflurane and enflurane patients, although mean arterial pressure was somewhat lower and heart rate higher in the isoflurane patients during the course of long anaesthesias. Both isoflurane and enflurane patients had to be given extra colloids and occasionally vasodilators to maintain peripheral temperature during the long anaesthesias. No clinically adverse renal or hepatic effects were seen, but the liver enzyme activities of four isoflurane and enflurane patients increased after the long anaesthesias. The highest serum inorganic fluoride concentration was 44 mumol/l in the enflurane patients and 5.6 mumol/l in the isoflurane patients.

Adult↗
PubMed1984

Liver damage after halothane anaesthesia: analysis of cases in Finnish hospitals in 1972-1981.

A retrospective questionnaire revealed 11 patients with halothane related liver disturbances in Finland in 1972-1981. Seven of the cases were regarded as obvious and two as probable halothane hepatitis (HH). Four patients suffered HH twice, and none of the cases had a fatal outcome. The speed of onset of icterus correlated with the number of halothane exposures, as did the increase in liver enzyme (ASAT, ALAT) activities and the increase in serum bilirubin concentration. Halothane anaesthesia is strictly contraindicated if a nondefinite icterus has appeared after a previous exposure to halothane. It should not be given if unclear fever or prolonged nausea have followed a previous exposure. No major adverse effects or organ toxicity connected with enflurane were found.

Adult↗
PubMed1983

Effects of working environment on the liver in 10 anaesthetists.

Drug-metabolising ability, i.e. antipyrine half-life, in anaesthetists was significantly slowed (23%) at the end of summer vacation (2-4 weeks), as compared to prevacation values. Despite changes in either direction, the antipyrine half-lives, including four determinations within a year and a half from the ten anaesthetists, were within normal limits. Liver enzymes (aspartate aminotransferase, alanine amino-transferase, alkaline phosphatase) were also normal. In one anaesthetist the test for anti-HBsAg was positive in 1980, while in the others HBsAg and anti-HBsAg were negative in 1980 and 1981. The inorganic fluoride concentrations of serum and urine (determined four times) were at normal levels. Only in one anaesthetist was there a transient, surprisingly high, serum concentration (7.9 mumol/l), apparently unrelated to work exposure.

Adult↗
PubMed1982

Effect of mannitol and furosemide on urinary fluoride excretion of surgical patients anaesthetized with enflurane or halothane.

Urinary excretion of fluoride after enflurane anaesthesia has been found to correlate with urinary pH, while the correlation with urinary volume has remained unsettled. We therefore studied the effect of moderate doses of mannitol and furosemide on serum fluoride levels and urinary excretion of fluoride in surgical patients after controlled doses of enflurane (6+6+6 patients) or halothane (5+5+5 patients). The highest serum fluoride level was 31 mumol/1 in an enflurane patient (enflurane dose 1.26 end-tidal vol % x h) and 8 mumol/1 in a halothane patient (halothane dose 0.59 end-tidal vol. % x h). Mannitol caused th greatest mean excretion of fluoride (not significant (n.s)) in the enflurane patients without any marked rise in urinary pH or volume. Furosemide increased urinary output markedly but did not enhance urinary fluoride excretion or raise urinary pH. Compared with the control groups of both inhalation anaesthetic patients, the diuretics appeared to have no effect on the serum fluoride levels. In the enflurane patients there was a positive correlation between the change in fluoride clearance and the change in urinary pH, but no with the change in urinary volume during the first postoperative hours. On the other hand, in the halothane patients there was a positive correlation between the change in fluoride clearance and the change in urinary volume. A possible "fluoro-uretic" action of mannitol was also seen in the halothane patients, as in the later postoperative period fluoride excretion was greatest when mannitol had been given.

Adult↗
PubMed1981

Metabolic ability and enflurane defluorination in surgical patients.

Antipyrine clearance and half-life, which are measures of the hepatic metabolic ability, were determined prior to anaesthesia in 14 surgical patients. The antipyrine results correlated neither with the highest serum fluoride concentrations nor with the fluoride excretion in urine following administration of enflurane. Enzyme induction may therefore have little influence on enflurane metabolism in man. Inorganic fluoride concentrations in serum and in excreted urine were determined following the exposure of a total of 21 surgical patients to measured doses of enflurane. In the group of 14 patients tested for metabolic ability, a mean dose of 0.4 end-tidal vol. % X h enflurane resulted in a mean peak serum fluoride concentration of 6.8 mumol/l (maximum 13.6 mumol/l) 2 h after enflurane exposure. In the material as a whole, the enflurane dose was positively correlated with both post-anaesthetic highest serum fluoride concentrations and the 24-h post-anaesthetic urine pH (P less than 0.01) as well as urinary volume and fluoride excretion in urine during that time. At a urinary pH below 5.0, the fluoride excretion was very low, while the highest excretions were associated with a urinary pH of about 7.0. Raising the patient's per- and post-anaesthetic urine pH and maintaining a good urinary output (which also tends to increase urine pH) may be enough to prevent accumulation of inorganic fluoride in the body following enflurane anaesthesia.

Adolescent↗