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Biomedical subjects

M A McGuigan

Publications and source records attributed to M A McGuigan.

At least 19 recordsLinked to original sources
PubMed2005

Hyperbaric oxygen for carbon monoxide poisoning.

BACKGROUND: Poisoning with carbon monoxide (CO) remains an important cause of accidental and intentional injury worldwide. Several unblinded non-randomized trials have suggested that the use of hyperbaric oxygen (HBO) prevents the development of neurological sequelae. This has led to the widespread use of HBO in the management of patients with carbon monoxide poisoning. OBJECTIVES: To examine randomized trials of the effectiveness of hyperbaric oxygen (HBO) compared to normobaric oxygen (NBO) for the prevention of neurologic sequelae in patients with acute carbon monoxide poisoning. SEARCH STRATEGY: We searched MEDLINE (1966-present), EMBASE (1980-present), and the Controlled Trials Register of the Cochrane Collaboration, supplemented by a manual review of bibliographies of identified articles and discussion with recognized content experts. SELECTION CRITERIA: All randomized controlled trials involving non-pregnant adults acutely poisoned with carbon monoxide (regardless of severity), with adequate or unclear allocation concealment. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted from each trial information on: the number of randomized patients, types of participants, the dose and duration of the intervention, and the prevalence of neurologic symptoms at follow-up. MAIN RESULTS: Seven randomized controlled trials of varying quality were identified; one was excluded because it did not evaluate clinical outcomes. Of the six remaining trials, two represent incomplete publications (one interim analysis, one abstract). Of these six trials, four found no benefit of HBO for the reduction of neurologic sequelae, while two others did. Although pooled analysis does not suggest a benefit from HBOT (OR for neurological deficits 0.78, 95%CI 0.54 to 1.12, p=0.18), significant methodologic and statistical heterogeneity was apparent among the trials, and this result should be interpreted cautiously. Moreover, design or analysis flaws were evident in all trials. Importantly, the conclusions of one positive trial may have been influenced by failure to adjust for multiple hypothesis testing, while interpretation of the other positive trial is hampered by apparent changes in the primary outcome during the course of the trial. AUTHORS' CONCLUSIONS: Existing randomized trials do not establish whether the administration of HBO to patients with carbon monoxide poisoning reduces the incidence of adverse neurologic outcomes. Additional research is needed to better define the role, if any, of HBO in the treatment of patients with carbon monoxide poisoning. This research question is ideally suited to a multi-center randomized controlled trial.

Carbon Monoxide Poisoning↗
PubMed2004

Dying to be thin: a dinitrophenol related fatality.

2, 4-dinitrophenol (DNP) was originally used as an explosive and later introduced in the 1930's to stimulate metabolism and promote weight loss. It's also a component of pesticides still available globally. Concerns about hyperpyrexia lead to DNP being banned as a dietary aid in 1938. A 22-y-old male presented to the Emergency Department (ED) with a change in mental status 16 h after his last dose of DNP. On admission he was diaphoretic and febrile with an oral temperature of 102 F, but lucid and cooperative. He became agitated and delirious. Intravenous midazolam was initiated with mechanical cooling. Pancuronium was administered later and the patient was intubated. Over the next hour the patient became bradycardic, then asystolic, and despite resuscitative efforts, died. Advertisements claim DNP safe at the dose our patient ingested. It is widely available and with the potential to cause severe toxicity is an understudied public health concern.

2,4-Dinitrophenol↗
PubMed2001

Availability of antidotes at acute care hospitals in Ontario.

BACKGROUND: Acutely poisoned patients sometimes require immediate treatment with an antidote, and delays in treatment can be fatal. We sought to determine the availability of 10 antidotes at acute care hospitals in Ontario. METHODS: Mailed questionnaire with repeated reminders to pharmacy directors at all acute care hospitals in Ontario. RESULTS: Responses were obtained from 179 (97%) of 184 hospitals. Only 9% of the hospitals stocked an adequate supply of digoxin immune Fab antibody fragments, a life-saving antidote for patients with severe digoxin toxicity, whereas most of the hospitals stocked sufficient supplies of ipecac syrup (88%) and flumazenil (92%), arguably the least crucial antidotes in the survey. Only 1 hospital stocked adequate amounts of all 10 antidotes. Certain hospital characteristics were associated with adequate antidote stocking (increased annual emergency department volume, teaching hospital status and designation as a trauma centre). Conversely, antidote supplies were particularly deficient at small hospitals and, paradoxically, geographically isolated facilities (those most reliant on their own inventory). The cost of antidotes correlated only weakly with stocking rates, and many examples of excessive antidote stocking were identified. INTERPRETATION: Most acute care hospitals in Ontario do not stock even minimally adequate amounts of several emergency antidotes, possibly jeopardizing the survival of an acutely poisoned patient. Much of this problem could be rectified at no additional cost by reducing excessive stock of expensive antidotes and redistributing the resources to acquire deficient antidotes.

Antidotes↗
PubMed2000

Hyperbaric oxygen for carbon monoxide poisoning.

BACKGROUND: Poisoning with carbon monoxide (CO) remains an important cause of accidental and intentional injury worldwide. Several unblinded nonrandomized trials have suggested that the use of hyperbaric oxygen (HBO) prevents the development of neurological sequelae. This has led to the widespread use of HBO in the management of patients with carbon monoxide poisoning. OBJECTIVES: To assess the effectiveness of hyperbaric oxygen (HBO) compared to normobaric oxygen (NBO) for the prevention of neurologic symptoms in patients with acute carbon monoxide poisoning. SEARCH STRATEGY: We searched MEDLINE (1966-present), EMBASE (1980-present), and the Controlled Trials Register of the Cochrane Collaboration, supplemented by a manual review of bibliographies of identified articles and discussion with recognized content experts. SELECTION CRITERIA: All randomized controlled trials involving non pregnant adults acutely poisoned with carbon monoxide, regardless of severity, with adequate or unclear allocation concealment were examined. Trials with a score of 3 out of 5 or higher on the validity instrument of Jadad were included in the primary analysis. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted from each trial information on the number of randomized patients, types of participants, the dose and duration of the intervention, and the prevalence of neurologic symptoms at follow-up. A pooled odds ratio (OR) for the presence of neurologic symptoms at one month follow-up was calculated using a random effects model. MAIN RESULTS: Six randomized controlled trials were identified. The trials were of varying quality. Three trials employing different doses of NBO and HBO were included in the primary analysis. The severity of CO poisoning was inconsistent between trials. At one month follow-up after treatment, symptoms possibly related to carbon monoxide poisoning were present in 81 of 237 patients (34.2%) treated with HBO, compared with 81 of 218 patients (37.2%) treated with NBO (O.R. for benefit with HBO 0.82; 95% CI 0.41-1.66). REVIEWER'S CONCLUSIONS: There is no evidence that unselected use of HBO in the treatment of acute CO poisoning reduces the frequency of neurological symptoms at one month. However, evidence from the available randomized controlled trials is insufficient to provide clear guidelines for practice. Further research is needed to better define the role of HBO, if any, in the treatment of carbon monoxide poisoning. This research question is ideally suited to a multicentre, randomized, double-blind controlled trial.

Carbon Monoxide Poisoning↗
PubMed2000

Gastrointestinal decontamination for enteric-coated aspirin overdose: what to do depends on who you ask.

CONTEXT: Overdoses with enteric-coated preparation are common. The optimal means by which to limit drug absorption in such cases is controversial. OBJECTIVE: To describe the recommendations for gastrointestinal decontamination issued by North American poison control centers for a hypothetical patient, (an adult male with normal vital signs), presenting 1 hour after ingesting 500 mg/kg of enteric-coated aspirin. DESIGN: Telephone survey of 76 poison control centers in North America. Seven toxicologists who contributed to the American Academy of Clinical Toxicology/European Association of Poison Centres and Clinical Toxicologists position statements on gastrointestinal decontamination were also surveyed for informal comparison. RESULTS: Most poison control centers (99%) and all of the toxicologists (100%) participated in the survey. Four centers (5 %) recommended syrup of ipecac and 38 (51%) recommended gastric lavage, compared with 0% and 0% of toxicologists, respectively. Seventy-three centers (97%) recommended at least one dose of activated charcoal, compared with 6 toxicologists (86%). Twenty-one poison centers (28%) recommended whole-bowel irrigation, compared with 3 toxicologists (43%). A total of 36 different courses of action were suggested by respondents at the poison centers. Some of these recommendations were potentially harmful. CONCLUSIONS: Considerable variability exists in the recommendations of North American poison control centers for the gastrointestinal decontamination of patients with large, acute overdoses of enteric-coated aspirin.

Adult↗
PubMed2000

Gastric perforation attributable to liquid nitrogen ingestion.

Despite the widespread use of liquid nitrogen in medicine and industry, there are only a few reports of injuries associated with its use. We report a case of a 13-year-old boy who developed gastric perforation after liquid nitrogen ingestion. This is a previously unreported complication.

Administration, Oral↗
PubMed1998

Management of anaphylactoid reactions to intravenous N-acetylcysteine.

STUDY OBJECTIVE: To develop management guidelines for the treatment of anaphylactoid reactions to intravenous N-acetylcysteine (NAC) and to assess the safety of restarting the infusion after a reaction. METHODS: In phased 1, we used a 6-year retrospective case series of hospitalized patients and a review of the literature to develop the management guidelines for anaphylactoid reactions to intravenous NAC. In phase 2, these guidelines were evaluated prospectively in our poison-control center. RESULTS: In phase 1, the charts of 11 patients with anaphylactoid reactions (9 cutaneous and 2 systemic) were reviewed. In most cases, no treatment or treatment with diphenhydramine alone or with salbutamol was sufficient to continue or restart NAC infusion safely. On the basis of our findings in those patients and on published experience, we concluded that anaphylactoid reactions to intravenous NAC are dose-related and the antihistamines are useful in controlling and in preventing recurrence of anaphylactoid symptoms. We developed the following guidelines: flushing requires no treatment, urticaria should be treated with diphenhydramine, and NAC infusion should be continued in both cases. Angioedema and respiratory symptoms each require the administration of diphenhydramine and symptomatic therapy. In these cases, NAC infusion should be stopped but, when necessary, can be started 1 hour after the administration of diphenhydramine in the absence of symptoms. In phase 2, 50 patients (31 cutaneous and 19 systemic reactions) were treated prospectively with the use of these guidelines. Recurrence of symptoms occurred in only one case involving a deviation from the guidelines. The NAC infusion was restarted immediately after the administration of diphenhydramine in a patient who sustained a systemic reaction. CONCLUSION: Non-life-threatening anaphylactoid reactions to intravenous NAC are treated easily and the infusion may be continued or restarted safely after the administration of diphenhydramine.

Acetaminophen↗
PubMed1998

Carbamazepine interference with an immune assay for tricyclic antidepressants in plasma.

BACKGROUND: Drug toxicological screening is commonly used as a diagnostic tool in patients with suspected toxic ingestion. False positive results due to cross-reactive compounds in drug assays may lead to misdiagnosis and mismanagement, especially when child abuse is suspected. CASE REPORT: Two of our patients with history of ingestion of carbamazepine were tested positive on screening with the tricyclic antidepressant immunoassay. The immunoassay's known cross-reactivity for carbamazepine is reportedly as low as 0.3%. Plasma samples of our patients were initially considered positive for tricyclic antidepressants because the cross-reaction of carbamazepine gave tricyclic antidepressant concentrations as imipramine equivalent sufficiently above the assay cut-off point (20 ng/mL). Later, confirmatory urine testing of both patients using high-performance liquid chromatography was negative for tricyclic antidepressants. CONCLUSION: This interference has significant clinical implications, and can be avoided on urine testing using a specific chromatographic assay such as high-performance liquid chromatography.

Adolescent↗
PubMed1997

Acute dapsone intoxication: a pediatric case report.

INTRODUCTION: There are many case reports of dapsone overdose in adults but only a few reports of dapsone-induced methemoglobinemia in children. We report a case of a three-year-old boy who developed prolonged recurrent methemoglobinemia following an ingestion of dapsone. METHODS: Case report. ETHICS: Not applicable. STATISTICS: Not applicable. RESULTS: This child developed significant symptoms of methemoglobinemia approximately two hours after ingesting dapsone 37.5 mg/kg. The initial methemoglobin level measured 2.5 hours after ingestion was 44%. The patient was treated with multiple doses of activated charcoal and methylene blue. Three doses of methylene blue reduced the methemoglobin level to 6% by approximately 16 hours after the overdose but the level rebounded to nearly 15% at 64 hours postingestion. DISCUSSION: Dapsone is a drug that is being used for a wide variety of clinical conditions. The primary clinical manifestation of dapsone overdose is methemoglobinemia. An important aspect of dapsone poisoning is its ability to produce methemoglobinemia, which is long lasting and which may recur following methylene blue therapy. Because of this, dapsone-poisoned children need to be monitored for two to three days.

Antimalarials↗
PubMed1997

Quality management for poison centers.

BACKGROUND: Poison centers are struggling with the concept of service quality and how to improve it. The business world has dealt with this concept by establishing internationally agreed-upon criteria for quality management. Poison centers deliver health care services and can benefit from the approach taken by the corporate community. METHODS: This review article takes the criteria of quality management proposed by the ISO 9000 series guidelines and demonstrates their applicability to poison center operations by translating the business jargon of the ISO 9000 series into terminology more familiar to health care professionals and by providing examples and approaches to satisfy specific guidelines. This article offers poison center staff a framework to help them understand how to improve the quality of service they provide.

Communication↗
PubMed1997

Two cases of chlorinated hydrocarbon-associated myocardial ischemia.

Chlorinated hydrocarbons are well known to produce ventricular arrhythmias because of myocardial sensitization to endogenous catecholamines, but cases of myocardial ischemia have not been described frequently. We report 2 cases of myocardial ischemia after exposure to chlorinated hydrocarbons. The first patient developed an asymptomatic myocardial infarction after inhalation of 1,1,1-trichloroethane at work. It is believed that 1,1,1-trichloroethane produced a coronary spasm that was sufficient to cause myocardial necrosis in the presence of coronary vessels already compromised by atherosclerosis. The second patient developed a reversible symptomatic myocardial ischemia of 4 h duration after chloral hydrate overdose. The evolution in both patients was favorable. Exposure to chlorinated hydrocarbons can be associated with myocardial ischemia particularly if the coronary circulation is already compromised.

Adult↗
PubMed1996

Acute iron poisoning.

The acute ingestion of medicinal iron preparations may result in serious poisoning, particularly in young children. The principle products involved are adult iron preparations, with or without vitamins. Although a single value for the toxic dose has not been established, significant gastrointestinal manifestations occur following the ingestion of 20 mg of elemental iron per kilogram of body weight while systemic toxicity may occur following the ingestion of at least 60 mg of elemental iron per kilogram of body weight. Treatment consists of stabilizing vital functions, removing unabsorbed iron from the gastrointestinal tract, and administering intravenous deferoxamine when there are serious clinical symptoms or when a serum iron level > 500 micrograms/dL is measured within 8 hours of the ingestion. Optimal management, with the involvement of a medical toxicologist or a regional poison control center, often results in a favorable outcome.

Child↗
PubMed1995

The geographic distribution of tuberculosis and pyridoxine supply in Ontario.

Acute poisoning with isoniazid causes generalized convulsions which should be treated with intravenous pyridoxine and a rapidly-acting anticonvulsant. The purpose of this study was to determine the correlation between the distribution of tuberculosis (as a proxy for isoniazid use) and acute care hospital supplies of intravenous pyridoxine (the antidote for isoniazid overdose). The distribution of tuberculosis was based on Ontario public health regions. The study was descriptive using simple linear regression to assess the degree of correlation. Only 15.6% of Ontario acute care hospitals have enough intravenous pyridoxine to treat an average isoniazid overdose. The distribution of tuberculosis and the number of hospitals in the region correlated best with hospital supplies of pyridoxine, although these variables explained only 22% and 23.7%, respectively, of the variation in supply. It does not appear that the distribution of tuberculosis is a major determinant of the availability of the isoniazid antidote, pyridoxine. Acute care hospitals in Ontario should re-evaluate their need for pyridoxine in light of the incidence of tuberculosis in their regions. Each hospital should stock at least 5 Gm of intravenous pyridoxine; additional amounts may be appropriate if there is an increased incidence in the area.

Antitubercular Agents↗
PubMed1994

Human exposures to tilmicosin (MICOTIL).

Tilmicosin is a new veterinary antibiotic that has significant cardiovascular toxicity when administered in large doses. Over 30 mo, the Ontario Regional Poison Information Centre at The Hospital for Sick Children in Toronto collected 36 cases of accidental human exposure to tilmicosin. Analysis of the cases revealed that 75% of the patients were exposed to probably less than 1 mL of tilmicosin, that 72% of exposures resulted from needle punctures, and that local symptoms predominated. Based on the information gathered, it is recommended that patients with accidental exposures of less than 1 mL of tilmicosin be treated symptomatically and do not need to be evaluated in a hospital setting.

Accidents↗
PubMed1988

Caffeine overdose in an adolescent male.

A 16 year old male who ingested an estimated 6-8 grams of caffeine is described. Caffeine is commonly thought to be harmless, but its wide availability has promoted abuse. This patient manifested many of the adverse effects seen in acute caffeine ingestion including hypokalemia, elevated blood glucose, tachycardia, bigeminy and agitation. Respiratory alkalosis and chest pain, which have not been previously reported to our knowledge in caffeine overdose, were also noted in this patient. Three serum caffeine levels were analyzed and an abnormally long elimination half-life of approximately 16 hours was calculated from the results.

Adolescent↗
PubMed1988

Acute tricresylphosphate intoxication in childhood.

Tricresylphosphates (TCP) have been responsible for a large number of epidemic and individual intoxications since the recognition, in 1899, that phospho-creosote was the cause of paralysis in patients being treated for tuberculosis. Although children are mentioned as being among the victims of epidemic intoxication, no well documented reports of acute tricresylphosphate ingestion in childhood are available in the literature. We report a case of severe intoxication in a 4 1/2-year-old child following ingestion of a lubricant containing TCP. Clinical findings in this child were typical of previously reported acute ingestions in adults: acute gastro-intestinal symptoms, delayed cholinergic crisis and neurological toxicity. Previous literature is reviewed briefly and discussed.

Child, Preschool↗
PubMed1987

Ipecac-induced emesis and reduction of plasma concentrations of drugs following accidental overdose in children.

Syrup of ipecac is widely used following accidental drug overdosage in children. Proof of its efficacy, however, in reducing the risk of poisoning is limited. We prospectively studied the effect of early v late induction of emesis by ipecac in 50 children younger than 5 years of age with accidental acetaminophen poisoning. The mean estimated ingested dose was 165 mg/kg, and all patients vomited within 15 to 255 (mean 78) minutes postingestion. Although the predicted four-hour plasma acetaminophen concentration was 97 +/- 4 micrograms/mL (mean +/- SEM, calculated on the basis of the estimated ingested dose), the measured four-hour plasma acetaminophen concentration was 34 +/- 5 micrograms/mL (P less than .01). To assess the efficacy of early v late ipecac-induced emesis, we used the ratio of measured to predicted four-hour acetaminophen plasma concentration. The ratio of the measured to predicted four-hour level increased as the delay in time to vomiting increased (r = .60, P less than .001). Ipecac syrup was administered more promptly when available in the home than when obtained from a pharmacy or a medical facility (26 +/- 8 v 83 +/- 13 minutes postingestion, respectively; P less than .001) and vomiting occurred earlier (49 +/- 9 v 103 +/- 12 minutes postingestion; P less than .01). Although the mean estimated doses ingested were greater in patients who received ipecac syrup at home, their four-hour plasma acetaminophen concentrations were lower. These data suggest that prompt administration of ipecac syrup results in a greater reduction in plasma acetaminophen concentrations in potentially toxic overdosages in children.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Home↗