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Biomedical subjects

M H Dykes

Publications and source records attributed to M H Dykes.

At least 19 recordsLinked to original sources

Postoperative hepatic dysfunction in perspective. 1970.

Postoperative hepatic dysfunction will remain a difficult entity to place in perspective until increased data are obtained from prospective clinical trials. Ideally these data should compare hepatic dysfunction not only to other postoperative complications, both with regard to overall incidence and to mortality, but also to the overall risks of anesthesia and surgery. The contribution of drug-induced hepatic damage to postoperative hepatic dysfunction has remained unsettled since chloroform was first incriminated during the nineteenth century. The drug was condemned in 1912, without any attempt being made to determine the incidence of the so-called delayed chloroform poisoning, with the result that the drug is still in use and the chloroform controversy remains unsettled to this day. The halothane controversy is also unsettled and currently overshadows the former controversy, although academically of no greater importance. Although not an anesthetic, cincophen is another drug about which there is controversy concerning its hepatotoxic potential. Babior and Davidson noted that it was the first drug implicated in hepatic necrosis--presumably with the exception of chloroform--the first report appearing in 1922. In 1941 the Council on Pharmacy and Chemistry of the American Medical Association concluded that the case against cincophen was not proved and that an urgent need existed for controlled clinical studies. Twenty-five years later Babior and Davidson noted that such studies had still not been undertaken and that the situation was the same as it was a quarter of a century earlier. Perhaps the time has come for a prospective, randomized, controlled clinical trial to be undertaken so as to evaluate the hepatotoxicity of one of these drugs. Perhaps an anesthetic agent such as halothane, concerning multiple administrations of which there is currently serious question, would be a suitable choice for such a study. The drug is in wide use today, partly because of evidence of satisfactory death rates following its administration, but also because on the basis of much excellent physiological data--but an almost total lack of any confirmatory epidemiological evidence--it is thought to contribute positively toward a low overall incidence of postoperative morbidity. Perhaps in addition, as a corollary, the time has come when, as attempts to illuminate a well--enunciated problem of this nature--that is, to test a clearly formulated hypothesis--the isolated case report, the collection of isolated case reports, the series of patients reported in the absence of a proven comparable control group, and the uncontrolled survey, should be "laid to rest." At best they provide only additional hypothesis-formulating information. At worst, however, they give increased exposure to a suggestion concerning cause and effect upon which physicians may act to their patients' detriment if the hypothesis ultimately proves to be erroneous. MacMahon et al. have stated that although there is no clear-cut dividing line between descriptive and analytical epidemiology, most epidemiological studies can indeed be classified primarily as either hypothesis-formulating or hypothesis-testing. Just as we have conducted the definitive retrospective hypothesis-testing study--the National Halothane Study--demanded by the "halothane hepatitis" controversy, so must we now move to the final stage of epidemiological investigation (experimental epidemiology) by investigating the effects of multiple administrations of the drug. On this point the National Halothane Study acts more as a hypothesis-formulating study than as a hypothesis-testing study. Hill has noted that statistical problems must be dealt with by the statistical method. (ABSTRACT TRUNCATED)

Anesthetics, Inhalation↗

Awake fibreoptic intubation in the patient at high risk of aspiration.

This report describes our experiences with 129 awake oral and nasal fibreoptic intubations in 123 patients considered to be at high risk of aspiration of gastric contents. I.v. sedation was used on all but six occasions. Local anaesthesia was applied to the larynx and trachea through the working channel of the fibrescope on 85 occasions, and by transtracheal injection on 29. Rigid laryngoscopy was necessary after fibreoptic laryngoscopy failed in one patient (with a bleeding peptic ulcer) who vomited a large amount of fresh and clotted blood. No other patient regurgitated during the procedure, and no patient developed evidence of aspiration.

Aged↗

Dissemination of fibreoptic airway endoscopy skills by means of a workshop utilizing models.

A questionnaire was mailed to 182 attendees of four practical workshops on fibreoptic endoscopy. After the workshops, 35% of the attendees were able to introduce fibreoptic intubation into their clinical practice or improve their success rate. This suggests that a new psychomotor skill can be disseminated effectively to clinicians by a practical workshop that utilizes inanimate models, and is based on sound educational principles.

Adult↗

Learning fibreoptic intubation: use of simulators v. traditional teaching.

This study compared a graduated training programme with that of a traditional teaching method to facilitate the learning of the technique of fibreoptic nasotracheal intubation. Thirty-two anaesthesia trainees were randomly assigned to two groups. The graduated programme involved: practice on a bronchoscopy teaching model; exposure of the epiglottis and vocal cords in patients recovering from general anaesthesia; performance of fibreoptic nasotracheal intubation in awake sedated patients. The traditional programme involved: demonstration (on a patient) of one fibreoptic nasotracheal intubation by the instructor; performance of fibreoptic nasotracheal intubation (by the trainee) in awake sedated patients. Nasotracheal intubation was accomplished significantly more often by the trainees in the graduated programme (86 out of 96 (89.6%) v. 64 out of 96 (66.5%) (P less than 0.01). The results demonstrate that trainees who undergo a graduated training programme using simulators are initially more successful at awake fibreoptic nasotracheal intubation than those who have learned in the traditional manner, and that the conditions of the investigation were acceptable to the trainees and patients.

Anesthesiology↗

Multiple neuromuscular blocking agents and reversal in a patient with absent plasma cholinesterase.

The detailed clinical response of a patient with absent plasma cholinesterase (genotype E1s E1s) who received tubocurarine (3 mg), succinylcholine (120 mg), pancuronium (2 mg), and reversal with neostigmine (3 mg) is reported. The patient's responses were compared to the responses of a group of patients with genotype E1a E1a evaluated prospectively, and with eight other genotype E1s E1s patients reported in the literature. The present patient demonstrated evidence of a phase II block before and after attempted reversal, suggesting that free succinylcholine was present in her plasma and a mixed block was present at that time. Conservative supportive therapy was continued and a complete recovery resulted five hours and 30 minutes after the succinylcholine administration.

Adult↗

Statistical methods in anesthesia articles: an evaluation of two American journals during two six-month periods.

Simple criteria were used to evaluate the statistical analyses in 243 articles from two American anesthesia journals published in the latter six months of 1981 and 1983. Eighty-two percent of the articles reported the use of control measures and 37% reported randomization of treatment, where they were possible. Data were classified as nominal, ordinal, or interval; as independent or related samples; as two-sample or more-than-two-sample cases. The descriptive, inferential, and correlative tests used were evaluated for appropriate application and primary errors were identified. Nine percent of the 722 descriptive statistics had major errors, most of which were a description of ordinal data as though they were interval. The incidence of erroneous applications of 394 inferential statistical tests was 78%. Nearly three-quarters of the 308 primary inferential statistical errors involved either use of a test for independent samples on related data (and vice versa) or multiple applications of an uncorrected test to the same data. Only 4% of the 113 statistics of association were considered erroneous, most because the method was not identified. No differences were detected in the incidence of errors in either experimental design or statistical analysis across time or across the two anesthesia journals. Fifteen percent of the 243 articles in both journals at both times were without major errors in statistical analysis. Recognition of potential sources of error should make it easier for investigators to use experimental designs and statistical analyses appropriate to their needs.

Anesthesia↗

Ascorbic acid and the common cold. Evaluation of its efficacy and toxicity.

We reviewed the clinical data relating to the efficacy and safety of pharmacologic doses of ascorbic acid in the prevention and treatment of the common cold. Although one study tentatively supports the hypothesis that such doses of ascorbic acid may be efficacious, a second study by the same group did not confirm the significant findings, and no clear, reproducible pattern of efficacy has emerged from the review of all the evidence. Similarly, there is currently little adequate evidence on either the presence or the absence of serious adverse reactions to such doses of ascorbic acid, although many such reactions have been hypothesized. The unrestricted use of ascorbic acid for these purposes cannot be advocated on the basis of the evidence currently available.

Administration, Oral↗

Evaluation of a muscle relaxant: dantrolene sodium (Dantrium).

Dantrolene sodium (Dantrium) is a skeletal muscle relaxant, unique in that it acts on the muscle itself. It should be considered for use in patients with skeletal muscle spasticity who are in a stable neurological state. After careful adjustment of the dose, a substantial number of such patients will experience one or more of the following benefits: (1) a reduction in pain, (2) an increased ability to make use of residual motor function, (3) a reduction in the level of nursing care required, (4) an increased ability to utilize devices, and (5) an increased ability to participate in rehabilitation. The drug should not be used when reduced spasticity will decrease functional ability. The adverse effects generally are transient; some are the result of central nervous system depression.

Activities of Daily Living↗