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Biomedical subjects

R Krivosic-Horber

Publications and source records attributed to R Krivosic-Horber.

At least 91 records · Page 5Linked to original sources
PubMed1988

[Calcium inhibitors and anesthesia].

Calcium blockers (CB) are routinely used. This could lead to possible interference with anaesthetic drugs. CB prevent calcium from entering the cell by inhibiting the slow voltage-dependent calcium channels. They act mostly on heart and smooth muscle. Of all the possible indications, the three that are confirmed are coronary heart disease, arterial hypertension and supraventricular rhythm disturbances. Most of the work published and the cases reported concerns interactions between CB and halogenated anaesthetic agents; the latter's actions on the heart depend on cellular calcium exchange. Also, the cardiovascular effects of these anaesthetics are similar to that of CB. Experimentally, halothane and enflurane have direct cardiac inhibitory effects similar to verapamil and diltiazem, whereas isoflurane's properties seem closer to the dihydropyridines (nifedipine and nicardipine). Giving verapamil or diltiazem increases the number of sino-atrial and atrio-ventricular blocks when using a halogenated agent. Clinically, interpreting the effects of CB during anaesthetic induction is difficult because of the pathology (coronary heart disease, cardiac failure), the other drugs (beta-blockers and nitrates) and the type of anaesthesia (emergency or elective). Interactions can give rise to anything from a severe cardiovascular collapse, requiring catecholamines, to a mild fall in blood pressure which responds well to plasma expansion, or even no effect on blood pressure. Rebound is seen on stopping CB in patients with coronary heart disease or arterial hypertension; stopping them before surgery does not therefore seem justified. However, extreme care must be taken when using halogenated agents for patients under treatment with CB and/or beta-blockers. A wary anaesthetist will be able to adapt the technique to the patient. It has been suggested that CB could be used to treat preoperatively myocardial ischaemia (diltiazem), hypertensive crises (nifedipine, nicardipine) and ventricular rhythm disturbances (verapamil); this must be done with caution, the patient being closely monitored (haemodynamic and electrocardiographic monitoring). Postoperatively, intranasal nifedipine, continuous intravenous nicardipine or diltiazem have been used to treat increases in arterial blood pressure during recovery and to adapt the cardiovascular system to the increased metabolic needs. Here again, close patient monitoring is essential. In any case, treatment with CB which has been stopped should be started up again as soon as possible.

Analgesics↗
PubMed1988

[Registration of peranesthetic cases of malignant hyperthermia in France. An update].

Sixty-two suspected crises of anaesthetic malignant hyperthermia (MH) were collected between 1969 and 1988 by a retrospective inquiry which lasted four years. 33 patients (53%) died whilst 29 survived. 20 cases were confirmed to be MH, either directly or indirectly by way of muscle biopsy and halothane and caffeine contracture tests carried out according to the European MH group protocol by two laboratories. This group included 11 of the deaths, one family member of whom, at least, is sensitive (MHS), 7 MHS survivors and 2 survivors too young to undergo muscle biopsy but belonging to MHS families. 21 cases were highly suspect of MH: 15 of the deaths which occurred in a typical way, and 6 patients of three different families who have suffered from anaesthetic deaths which, clinically, suggested MH. Another 15 were possible MH cases, all survivors, including one case of Steinert's disease and a brother of a case of central core disease. 2 cases were still being debated, because they had equivocal results for the caffeine test (MHEc); the last 4 had negative muscle biopsies and were excluded. 33 close relatives of the MH patients were diagnosed as MHS. 44 others were found to be free from the genetic predisposition. It was strongly recommended to yet 11 others that they carry the MHS card because they were MHEc. The clinical, surgical and anesthetic pictures were always as described in the literature. The anaesthetic protocols included inhalational agents in 90% of cases; these were combined with suxamethonium in 55% of cases. Dantrolene was only used in 32% of cases, and then at inadequate doses and very often too late; this probably explains the large number of treatment failures. The number of severe forms of MH was also very high in this series (70%). The need to increase the means of prevention and screening for MH in France is stressed.

Adolescent↗
PubMed1988

[Tests of contracture and sensitivity to malignant hyperthermia in 27 patients].

Twenty-seven patients, four of whom had presented with a crisis of malignant hyperthermia and the 23 other being close relatives of such patients, underwent a muscle biopsy so as to determine their susceptibility to malignant hyperthermia. Halothane-caffeine contracture tests, interpreted in accordance with the criteria of the European Group on Malignant Hyperthermia, yielded the following results: 13 positive (MHS), 10 negative (MHN), 4 equivocal (MHE). The history, clinical examination, CPK level, histoenzymatic morphology and electron microscopic study did not provide information sensitive enough to use for the detection of susceptibility to malignant hyperthermia. This confirmed the literature: the halothane-caffeine contracture test remains the only reliable diagnostic test to detect this susceptibility, despite the search for non invasive tests. If the mechanism of triggering a contracture to increasing doses of caffeine is well known in normal muscle, it is the smaller concentrations required which suggests malignant hyperthermia abnormality. The halothane effect is less well understood. A concentration less than or equal to 2 vol % yields a contracture only in MHS muscle. Differences in protocols used by American authors emphasize the importance of standardization as used by the European Group, which is the only way of collecting and comparing results on well over a thousand patients. This confrontation should reduce the number of equivocal diagnoses and allow a correct classification of patients at risk or their relatives as MHS or MHN.

Adolescent↗
PubMed1987

[Anesthesia for arthroscopy of the knee: propofol versus thiopental and halothane].

Sixty ASA I or II patients, who underwent general anaesthesia for arthroscopy of the knee, were separated into two groups. Induction was performed either with thiopentone 7 mg . kg-1 (group I) or with propofol 2.5 mg . kg-1 (group II). All patients were intubated and ventilated. Dextromoramide was used as analgesic. Maintenance of anaesthesia was obtained with halothane inhalation (group I) or by continuous automatic injection of propofol at a dose of 9 mg . kg-1 . h-1 (group II). Induction and maintenance were satisfactory in both groups. Pulse rate was stable at induction and intubation for the propofol group, whereas it increased at both stages of anaesthesia with thiopentone; it fell moderately in both groups afterwards. Systolic and diastolic blood pressures dropped more in the propofol group after induction, with a maximum decrease of 20%. Recovery was significantly more rapid and comfortable with propofol than with thiopentone.

Adult↗
PubMed1987

Neuroleptic malignant syndrome and malignant hyperthermia. In vitro comparison with halothane and caffeine contracture tests.

The in vitro halothane and caffeine contracture tests have been performed on muscle tissue from six survivors of the neuroleptic malignant syndrome. The results, which are expressed in accordance with the criteria of the European MH Group, defined five of the subjects as MHN and one patient as MHE. It is concluded that there is no common pathophysiological link between the neuroleptic malignant syndrome and malignant hyperthermia.

Adult↗
PubMed1986

[Examination of the family of a patient susceptible to anesthetic malignant hyperthermia].

The familial nature of anaesthetic malignant hyperthermia must lead to the search for susceptibility in other members of the family of a sensitive subject. According to the literature, only in vitro studies of contraction characteristics of biopsied skeletal muscle fibres exposed to caffeine or halothane are of predictive value. Four members of the family of a patient who died as a result of malignant hyperthermia were investigated. The results expressed in accordance with the criteria defined by the European group on malignant hyperthermia, coupled with a histoenzymatic study, defined three of the subjects as HMN (negative) and one subject as HM (c) (equivocal or intermediate).

Adolescent↗
PubMed1986

[Bronchial diffusion of ceftriaxone].

The value of a single daily injection of 2 g ceftriaxone in lower respiratory tract superinfections was demonstrated in 22 patients in a neurosurgical intensive care unit. Catheter bronchial samples were submitted to bacteriological investigation and ceftriaxone concentrations were determined in serum and bronchial secretions. Results show that sustained efficient levels of ceftriaxone were achieved and enabled the successful treatment of lower respiratory tract infections due to susceptible pathogens.

Adolescent↗