Management of the critically poisoned patient

Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine BioMed Central Review Open Access Management of the critically poisoned patient Jennifer S Boyle1, Laura K Bechtel1 and Christopher P Holstege*1,2 Address: 1Division of Medical Toxicology, Department of Emergency Medicine, University of Virginia School of Medicine, Charlottesville, Virginia, USA and 2Division of Medical Toxicology, Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia, USA Email: Jennifer S Boyle - ; Laura K Bechtel - ; Christopher P Holstege* - * Corresponding author Published: 29 June 2009 Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine 2009, 17:29 doi:10.1186/1757-7241-17-29 Received: 28 March 2009 Accepted: 29 June 2009 This article is available from: http://www.sjtrem.com/content/17/1/29 © 2009 Boyle et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: Clinicians are often challenged to manage critically ill poison patients. The clinical effects encountered in poisoned patients are dependent on numerous variables, such as the dose, the length of exposure time, and the pre-existing health of the patient. The goal of this article is to introduce the basic concepts for evaluation of poisoned patients and review the appropriate management of such patients based on the currently available literature. Methods: An unsystematic review of the medical literature was performed and articles pertaining to human poisoning were obtained. The literature selected was based on the preference and clinical expertise of authors. Discussion: If a poisoning is recognized early and appropriate testing and supportive care is initiated rapidly, the majority of patient outcomes will be good. Judicious use of antidotes should be practiced and clinicians should clearly understand the indications and contraindications of antidotes prior to administration. Introduction Poisoning emergencies commonly present to emergency departments. The clinical effects encountered in poisoned patients are dependent on numerous variables, such as the dose, the length of exposure time, and the pre-existing health of the patient. If a poisoning is recognized early and appropriate supportive care is initiated rapidly, the majority of patient outcomes will be good. The goal of this article is to introduce the basic concepts for evaluation and appropriate management of the poisoned patient. Resuscitation/Initial management The initial approach for evaluating the critically poisoned patient centers on thorough assessment, appropriate stabilization and supportive care [1]. It is important to consider a broad differential diagnosis that includes both toxicological and non-toxicological emergencies to avoid prematurely excluding potentially serious conditions. For example, an obtunded patient who smells of alcohol could also be harboring an intracranial hemorrhage and an agitated patient believed to be anticholinergic may in fact be encephalopathic due to a metabolic or infectious illness. Aggressive resuscitation is often required for the patient presenting with a toxicologic emergency. This follows a standard "ABC" approach with attention to "airway, breathing and circulation" respectively. The critically poisoned patient may present with central nervous system (CNS) depression or coma necessitating intubation in order to adequately protect the airway and reduce aspiration risk. Ventilatory drive may also be impaired resulting in CO2 narcosis with subsequent acidosis and mental staPage 1 of 11 (page number not for citation purposes) Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine 2009, 17:29 http://www.sjtrem.com/content/17/1/29 tus deterioration which may further increase risk for aspiration. Often this deterioration can be unrecognized in the patient placed on high flow oxygen because O2 saturation measures may remain adequate despite significant ventilatory failure. In assessing and managing circulatory status, appropriate intravenous access is essential. All severely poisoned patients should have at least one large bore peripheral intravenous catheter, and hypotensive patients should have a second intravenous line placed in either the peripheral or central circulation. Should vasopressor support be required, attention should be given to the specific poison as the mechanism producing hypotension may help direct the vasopressor selection. Agents with peripheral alpha antagonism, such as the atypical antipsychotic olanzapine, may respond well to direct alpha stimulation with phenylephrine [1]. Severe hypotension from tricyclic antidepressants, believed to be in part caused by depletion of biogenic amines, may respond to repletion with a direct alpha agonist such as norepinephrine when other agents such as the mixed alpha agonist dopamine have been ineffective [2]. Diagnostic approach Toxidromes Identification of the constellation of signs and symptoms that define a specific toxicologic syndrome, or "toxidrome", may narrow a differential diagnosis to a specific class of poisons [3]. Descriptions of selected toxidromes may be found in Table 1. Many toxidromes have several overlapping features. For example, anticholinergic findings are highly similar to sympathomimetic findings, with one exception being the effects on sweat glands: anticholinergic agents produce warm, flushed dry skin, while sympathomimetic produce diaphoresis. Toxidrome findings may also be affected by individual variability, comorbid conditions, and co-ingestants. For example, tachycardia associated with sympathomimetic or anticholin- ergic toxidromes may be absent in a patient who is concurrently taking beta antagonist medications. Additionally, while toxidromes may be applied to classes of drugs, some individual agents within these classes may have one or more toxidrome findings absent. For instance, meperidine is an opiate analgesic, but does not induce miosis that helps define the "classic" opiate toxidrome. When accurately identified, the toxidrome may provide invaluable information for diagnosis and subsequent treatment, although the many limitations impeding acute toxidrome diagnosis must be carefully considered. Hyperthermic syndromes Toxin induced hyperthermia syndromes include sympathomimetic fever, uncoupling syndrome, serotonin syndrome, neuroleptic malignant syndrome, malignant hyperthermia, and anticholinergic poisonings [4]. Sympathomimetics, such as amphetamines and cocaine, may produce hyperthermia due excess serotonin and dopamine resulting in thermal deregulation [5]. Treatment is primarily supportive and may include active cooling and administration of benzodiazepine agents. Un (...truncated)