THERE were almost 2.2 million human exposures CLINICAL INVESTIGATIONS. Emergency Department Observation of Poisoned Patients: How Long Is Necessary?

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1 ACADEMIC EMERGENCY MEDICINE September 1999, Volume 6, Number CLINICAL INVESTIGATIONS Emergency Department Observation of Poisoned Patients: How Long Is Necessary? JUDD E. HOLLANDER, MD, GLEN MCCRACKEN, MD, SCOTT JOHNSON, MD, SHARON M. VALENTINE, RN, MS, ANP, RICHARD D. SHIH, MD Abstract. Objective: To compare the emergency physician disposition decisions after observation periods of two, four, and six hours in a single cohort of ED patients with acute intentional ingestion to determine the accuracy of disposition decisions at two and four hours relative to the six-hour period of observation. Methods: This was a prospective observational study at two university hospital EDs. Study participants were patients with potentially toxic oral ingestions occurring less than six hours prior to ED presentation. Patients with isolated recreational drug or ethanol use were excluded. Structured data forms were completed at presentation, and two, four, and six hours later. Data included signs and symptoms consistent with toxic ingestion, physical examination, laboratory determinations, medications ingested, treatment, and suicide risk. At two and four hours, physicians were asked to determine whether they thought the patient was safe for medical clearance. These patients continued to be observed for six hours. The main outcome was whether patients initially thought to be appropriate for early medical clearance were ultimately cleared at six hours. Results: There were 260 patients enrolled: 28 were immediately admitted to the hospital and 17 were immediately discharged; 215 entered ED observation. Patients had a mean age of 24 years; 55% were female; 50% were suicidal; 17% had toxidromes. Of the 215 observed patients, 106 (49%) were deemed safe for early medical clearance at two hours. All 106 were ultimately cleared at six hours (100%, 95% CI = 97% to 100%). Of the 109 not safe for early medical clearance at two hours, 61 (56%) were deemed safe for early medical clearance at four hours; all 61 were subsequently discharged at six hours (100%; 95% CI = 95% to 100%). Overall, 167 of 215 (77%) observed overdose patients were deemed safe for early medical clearance after two or four hours of observation. All 167 were ultimately cleared at six hours (100%; 95% CI = 98.2% to 100%). Conclusions: A large subset of overdose patients who are medically cleared after six hours of observation can be identified within two to four hours of presentation. No patient who was believed to be safe for medical clearance at either two or four hours had a complication within the six-hour time period (95% CI = 0% to 1.8%). These data suggest that asymptomatic patients with selected acute intentional ingestions can be released from medical observation in less than six hours. Key words: poison; overdose; observation; treatment; emergency department; toxicology. ACADEMIC EMERGENCY MEDI- CINE 1999; 6: THERE were almost 2.2 million human exposures to toxic chemicals in 1997 reported to 66 poison centers across the United States. 1 Most From the Department of Emergency Medicine, University of Pennsylvania, Philadelphia, PA (JEH); Department of Emergency Medicine, University Medical Center, Stony Brook, NY (JEH, GM, SJ, SMV); Department of Emergency Medicine, Morristown Memorial Hospital Center, Morristown, NJ (RDS); and New Jersey Poison and Information System, Newark, NJ (RDS). Received: March 12, 1999; revision received: April 23, 1999; accepted April 30, Presented at the SAEM annual meeting, Washington, DC, May Address for correspondence and reprints: Judd E. Hollander, MD, Department of Emergency Medicine, 3400 Spruce Street, Philadelphia, PA Fax: ; jholland@mail.med.upenn.edu exposures to poisons, however, do not result in clinical toxicity. Based on American Association of Poison Control Centers (AAPCC) estimates, 88% of reported exposures had minimal or no effect on the subject or were reported as nontoxic, while fewer than 1% of overdose cases resulted in fatality. 1 Of the exposures reported to poison centers, only 22% of cases necessitated evaluation and treatment in a health care facility, while 75% of cases were managed at the site of exposure, usually the patient s home. 1 The remaining 3% of patients either refused a referral or had an unknown site of treatment. Despite the fact that many patients may be managed over the telephone, an extended observation period in the ED is often used for poison

2 888 OVERDOSES Hollander et al. TOXICOLOGY OBSERVATION PERIODS exposures initially presenting to the ED. 2 8 Commonly used clinical toxicology and emergency medicine textbooks recommend observation for overdose patients, but they do not specify the duration of the time period. 2 4 A survey of the AAPCC certified poison centers in 1994 by one of the authors revealed that 79% of the poison specialists who answered the phone recommended six hours of observation for a patient with an intentional ingestion of a single benign compound because the possibility of co-ingestants could not be excluded (unpublished data). To our knowledge, the duration of an ED observation period for potentially poisoned patients prior to ED release (discharge home or medical clearance for psychiatric evaluation) has never been studied in a broad ED-based population. The purpose of this study was to perform a preliminary assessment of the feasibility of a brief observation period for stable, minimally symptomatic or asymptomatic patients with potentially toxic ingestions. Specifically, we evaluated whether patient assessment at two to four hours could predict the six-hour disposition. We hypothesized that most patients with nontoxic acute intentional ingestions could be accurately identified within a two-to-four-hour period of observation. METHODS Study Design. We performed a prospective observational study of patients with potentially toxic ingestions presenting to the ED to assess the feasibility of a brief observation period for such patients. The study was reviewed and approved by both hospitals institutional review boards. Informed consent was not required for this observational study. Study Setting and Population. The study was performed in two university-based hospital EDs. One was located in suburban Long Island; the other was an inner-city hospital located in Newark, New Jersey. Patients who presented to the University Medical Center at Stony Brook ED within six hours of a potentially toxic ingestion between August 1994 and November 1995 were included. Patients who presented to Newark Beth Israel Medical Center within six hours of a potentially toxic ingestion were included when a single trained investigator was present. This investigator altered his shifts so that day, evening, night, weekend, and weekday presentations would be eligible. Thus, one hospital enrolled a convenience sample of patients, while the other enrolled consecutive patients. Both EDs were affiliated with regional poison control centers who were aware of the study protocol, and both poison control centers have quality assurance protocols that include next-day patient follow-up and notification of EDs of patients with adverse outcomes originally seen in that ED. Patients were included in the study if the ingestion occurred within six hours of ED presentation, and the initial disposition was ED observation. Patients were excluded from further analysis if they were immediately admitted to the hospital or immediately discharged from the ED; had isolated recreational drug use (e.g., cocaine, heroin, ethanol); or did not have an oral exposure (e.g., topical toxic exposures or IV drug use). Patients who ingested toxins that necessitated specific laboratory determinations or observation periods based on well-established literature were not excluded from this study. Although these patients would not be eligible for early medical clearance, they were included so that we could determine the percentage of patients who may or may not be eligible for early clearance. Enrollment into this study did not obligate the physician to evaluate or treat the patient in any manner other than that involving the treating physician s discretion. The decision to immediately admit or discharge a patient was left to the discretion of the attending physician. Measurements. A standardized closed-question data collection instrument was completed by the treating physician for each patient enrolled. Data collected included: demographic characteristics; time elapsed since ingestion; presence of 15 signs and symptoms (confusion, agitation/delirium, hallucinations, dizziness, vertigo, weakness/lethargy, headache, tinnitus, shortness of breath, chest pain, abdominal pain, nausea/vomiting, diarrhea, lacrimation/salivation, seizure); the pharmacologic class of drugs ingested; the specific drugs ingested, and any treatment provided in the ED. The structured physical examination included blood pressure, heart rate, respiratory rate, temperature, pupil size, character of bowel sounds, skin characteristics, and level of consciousness. The presence of toxidromes, as well as whether the patient s symptoms were consistent with the putative drug(s) ingested, was noted. Patient suicidal tendency was also assessed by the emergency physician (EP). After the initial patient assessment, the EP determined the initial patient disposition (admission, discharge, further observation). For purposes of this study, immediate discharge from the ED implied medical clearance of the patient, after which, if indicated, the patient may have been released home or transferred to the comprehensive psychiatric emergency program (a psychiatric ED). Patients who were in the ED were reevaluated

3 ACADEMIC EMERGENCY MEDICINE September 1999, Volume 6, Number at two, four and six hours after presentation. Subsequent documentation included whether any of the signs or symptoms noticed at presentation had resolved or persisted, as well as the appearance of new signs or symptoms. The same clinical, historical, and physical examination parameters were evaluated at two, four, and six hours following presentation. In addition, adjunctive laboratory data (arterial blood gas, serum electrolytes, serum osmolality, salicylate, acetaminophen, digoxin, lithium, and ethanol serum levels; ECG; and chest radiography results) were recorded. The physician made a determination of whether he or she thought the patient could have been medically cleared at each two-hour evaluation interval (two and four hours after presentation). Patients were observed for six hours to ensure that release at two or four hours would not have resulted in an adverse outcome. The patient s final disposition (at six hours) was recorded. Each physician used his or her own clinical judgment to determine the patient disposition. In order to medically clear patients, practice patterns at both institutions required resolution of presenting symptoms without development of new symptoms, no suspicion of long-acting medications or medications necessitating laboratory determination beyond the clearance time, and nontoxicologic explanations for all remaining symptoms (e.g., agitation in a patient with an adjustment disorder who did not ingest a toxin likely to result in agitation). Data Analysis. Data were entered into Dbase IV (Ashton-Tate, Torrance, CA) and imported into SPSS for Windows (SPSS Inc., Chicago, IL) for statistical analysis. The main outcome parameter for this study was the EP-reported disposition after six hours of observation. Continuous data are reported with descriptive statistics that measure central tendency (mean or median) and variability (standard deviation or interquartile range) depending on whether the data were normally distributed. Categorical data are reported as the percentage frequency of occurrence. Where appropriate, 95% confidence interval calculations were performed. Comparisons of patients who were deemed safe for medical clearance and patients who were not deemed safe for medical clearance were performed with chi-square tests for categorical data and t-tests for parametric continuous data. Alpha was preset at RESULTS Figure 1. Flow diagram of the study population. There were 260 patients with potentially toxic ingestions who presented to the EDs during the study period. Twenty-eight patients (11%) were immediately admitted due to the severity of their ingestions and 17 patients (7%) were immediately discharged from the ED because they were determined to have nontoxic ingestions. Patients who were immediately admitted had ingested toxins known to result in delayed manifestations, had levels that predicted toxic outcomes, required specific interventions, or presented with severe toxicity necessitating admission for medical management. Those patients who were immediately discharged from the ED were determined to have nontoxic ingestions based on history and physical examination. The remaining 215 patients entered ED observation and form the basis for the study group (Fig. 1). The mean patient age was years (range, 1 95 years). Thirty-seven patients (14%) were 2 years of age; 108 (42%) were 18 years old. One hundred nineteen patients were female (55%). Fifty percent expressed suicidal ideation. Toxidromes were initially present in 17% of the patients. Patients presented a median of two hours after ingestion (interquartile range, 1 2 hours): 114 patients (49%) presented within one hour of ingestion; 172 (75%) within two hours. Fifty-eight patients (27%) ingested more than one substance. The classification of ingested substances is shown

4 890 OVERDOSES Hollander et al. TOXICOLOGY OBSERVATION PERIODS TABLE 1. Classification of Substances Taken by Patients Who Presented to the ED with Intentional Oral Ingestions Substance Class* Number of Ingestions Alcohols 32 Amphetamines 4 Analgesics (includes aspirin and acetaminophen) 68 Anticholinergics 7 Anticoagulants 3 Anticonvulsants 2 Antidepressants (includes tricyclic and phenothiazines) 33 Antihistamines 25 Antibiotics 4 Asthma medications 2 Barbiturates 3 Benzodiazepines 38 Caffeine 1 Cardiovascular medications 8 Caustics 3 Cleaning agents 3 Cocaine 3 Cough and cold preparations 12 GI preparations 4 Hydrocarbons 3 Organophosphates/carbamates 1 Iron 4 Muscle relaxants 3 Opioids 14 Tobacco 1 Vitamins 1 Unknown 6 *Two patients ingested long-acting medications (an ACE inhibitor and a beta-antagonist). Both were immediately admitted to the hospital. Some patients ingested two or more toxins. These substances were always co-ingestants. in Table 1. Only two patients ingested long-acting medications [an angiotensin-converting enzyme (ACE) inhibitor and a long-acting beta antagonist]; both were immediately admitted, and thus excluded from the group of 215 patients initially observed in the ED. The signs, symptoms, and physical examination abnormalities shown by the 215 patients at the time of ED presentation are listed in Table 2. Of the study patients, 79% were treated with activated charcoal and cathartic, 8% received gastric lavage, 8% were treated with a specific antidote, and 2% received alkalinization therapy. No patient received syrup of ipecac in the ED. Of the 215 patients observed, 106 (49%) were deemed medically safe for discharge after two hours of observation. All of these 106 patients were ultimately discharged from the medical ED at six hours (95% CI = 97.2% to 100%). Of these 106 patients deemed medically safe for clearance at two hours, only 3% manifested physical examination abnormalities, while 28% of the 109 patients deemed not safe for clearance still had physical exam abnormalities (p < ). Patients deemed safe for medical clearance were less likely to have abnormalities in heart rate and level of consciousness, and were less likely to have been weak or lethargic, confused, nauseated, or complaining of headache (Table 3). Three patients cleared at two hours had physical examination abnormalities and ten patients had some minor residual signs and symptoms. The most common symptom was weakness. These patients most commonly had taken sedative/ hypnotics, were observed for a brief period of time, and were considered to have resolving symptoms. The one agitated patient was agitated due to a personality disorder. These patients were candidates for early medical clearance and release home in the care of a significant other. The two patients with physical examination abnormalities had a mild tachycardia (just above 100 beats/min) after ingestion of low doses of over-the-counter cold preparations. There were 109 patients not deemed medically safe for discharge at two hours. However, after four hours of ED observation, 61 of these 109 patients (56%) were considered medically safe for discharge. All 61 patients were ultimately discharged from the ED after six hours observation (95% CI = 95.1% to 100%). Patients deemed not safe for medical clearance after four hours of ED observation again were more confused, weak, or lethargic than those deemed safe. Physical examination abnor- TABLE 2. Patient Signs, Symptoms, and Physical Examination Abnormalities at the Time of Presentation Number (%) Clinical signs and symptoms Confusion 17 (8%) Agitation/delirium 19 (9%) Hallucinations 7 (3%) Dizziness 14 (6.5%) Vertigo 2 (1%) Weakness/lethargy 61 (28%) Headache 11 (5%) Tinnitus 1 (0.5%) Shortness of breath 4 (2%) Chest pain 0 (0%) Abdominal pain 10 (5%) Nausea/vomiting 21 (10%) Diarrhea 2 (1%) Lacrimation/salivation 2 (1%) Seizure 1 (0.5%) Physical examination abnormalities Blood pressure 4 (2%) Heart rate 47 (22%) Respiratory rate 5 (2%) Temperature 3 (1.4%) Pupils 17 (8%) Bowel sounds 9 (4%) Skin 12 (6%) Level of consciousness 22 (10%)

5 ACADEMIC EMERGENCY MEDICINE September 1999, Volume 6, Number TABLE 3. Patient Evaluation Two Hours after ED Presentation Patients Deemed Safe for Clearance (n = 106) Patients Not Safe for Clearance (n = 109) p-value Clinical signs and symptoms Confusion 0 (0%) 8 (7%) 0.01 Agitation/delirium 1 (1%) 6 (5.5%) 0.13 Hallucinations 1 (1%) 3 (3%) 0.63 Dizziness 0 (0%) 4 (4%) 0.14 Vertigo 0 (0%) 1 (1%) 1.00 Weakness/lethargy 4 (4%) 29 (27%) < Headache 0 (0%) 6 (5.5%) 0.04 Tinnitus 1 (1%) 0 (0%) 0.99 Shortness of breath 0 (0%) 1 (1%) 1.00 Chest pain 0 (0%) 0 (0%) Abdominal pain 1 (1%) 5 (4.6%) 0.23 Nausea/vomiting 2 (2%) 9 (7%) 0.07 Diarrhea 0 (0%) 1 (1%) 1.00 Lacrimation/salivation 0 (0%) 1 (1%) 1.00 Seizure 0 (0%) 1 (1%) 1.00 Physical examination abnormalities Any abnormality 3 (3%) 31 (28%) < Blood pressure 0 (0%) 1 (1%)* 1.00 Heart rate 2 (2%) 18 (16.5%) Respiratory rate 0 (0%) 1 (1%) 1.00 Temperature 0 (0%) 2 (2%) 0.49 Pupils 1 (1%) 6 (5.5%) 0.06 Bowel sounds 0 (0%) 4 (4%) 0.14 Skin 1 (1%) 2 (2%) 1.00 Level of consciousness 0 (0%) 12 (11%) *Systolic blood pressure <90 mm Hg. Two patients with heart rate (HR) >100 beats/min. Two patients with HR <60 beats/min; 16 patients with HR >100 beats/min. malities were significantly more common among those deemed not safe for medical clearance, especially alterations in the patients levels of consciousness (Table 4). There were a total of 11 patients who were cleared at four hours who had some signs, symptoms, or physical examination abnormalities remaining. Many of these patients had ethanol as a co-ingestant, had levels documented or anticipated to be below 100 mg/dl at four hours, and were mildly lethargic but easily aroused. Of the 48 patients not deemed safe for clearance at four hours, 22 (46%) were ultimately admitted to the hospital and 26 (54%) were cleared at six hours. The patients who were admitted to the hospital after six hours had ingested analgesics (7 patients), antidepressants (7 patients), benzodiazepines (3 patients), iron or vitamins (3 patients), antihistamines (2 patients), antiepileptic medications (2 patients), cardiovascular medications (2 patients), opiates (2 patients) and a muscle relaxant (1 patient). Overall, 167 of the 215 patients observed (77%) were deemed medically safe for early clearance within two four hours of ED presentation. All of these patients were ultimately cleared at six hours (95% CI = 98.2% to 100%). None developed any intercurrent medical complications (95% CI = 0% to 1.8%). DISCUSSION Although the poisoned patient continues to represent a significant percentage of ED encounters, there is a great deal of variability in the management and disposition of these patients. Current recommendations for the management of the poisoned patient is observation for up to six hours in the ED before disposition whether it is release home or medical clearance for psychiatric evaluation. 2 7 In symptomatic patients exposed to potentially fatal medications (e.g., tricyclic antidepressants, 9 monoamine oxidase inhibitors, 10 calcium antagonists, 11 cardiac glycosides, 12 acetaminophen, 13 theophylline, 14 methanol, 15 and ethylene glycol 16 ), admission to the hospital is usually clearly indicated. Admission or prolonged observation is required in some patients who have ingested drugs known to have delayed clinical effects, even though they may be asymptomatic at the time of presentation. The toxicity of some medications, such as aspirin, acetaminophen, lithium, iron, methanol, ethylene

6 892 OVERDOSES Hollander et al. TOXICOLOGY OBSERVATION PERIODS TABLE 4. Patient Evaluation Four Hours after ED Presentation Patients Deemed Safe for Clearance (n = 61) Patients Not Safe for Clearance (n = 48) p-value Clinical signs and symptoms Confusion 0 (0%) 4 (8.3%) 0.07 Agitation/delirium 0 (0%) 3 (6.3%) 0.16 Hallucinations 0 (0%) 2 (4.2%) 0.37 Dizziness 1 (1.6%) 1 (2.1%) 1.00 Vertigo 1 (1.6%) 0 (0%) 1.00 Weakness/lethargy 5 (8%) 17 (35.4%) Headache 1 (1.6%) 4 (8.4%) 0.23 Tinnitus 0 (0%) 0 (0%) Shortness of breath 0 (0%) 0 (0%) Chest pain 0 (0%) 0 (0%) Abdominal pain 1 (1.6%) 2 (4%) 0.83 Nausea/vomiting 1 (1.6%) 4 (8.4%) 0.23 Diarrhea 0 (0%) 1 (2.1%) 0.90 Lacrimation/salivation 0 (0%) 0 (0%) Seizure 0 (0%) 0 (0%) Physical examination abnormalities Any abnormality 6 (10%) 12 (25%) 0.03 Blood pressure* 0 (0%) 1 (2.1%) 0.90 Heart rate 3 (4.9%) 5 (10.4%) 0.47 Respiratory rate 0 (0%) 0 (0%) Temperature 1 (1.6%) 0 (0%) 1.00 Pupils 2 (3.3%) 3 (6.3%) 0.78 Bowel sounds 0 (0%) 1 (2.1%) 0.90 Skin 0 (0%) 2 (4.2%) 0.37 Level of consciousness 0 (0%) 9 (18.8%) *Systolic blood pressure <90 mm Hg. All patients with heart rate (HR) abnormalities (n = 8) had HR >100 beats/min. glycol, and carbon monoxide, may be somewhat predicted by quantitative drug levels, which can be used in conjunction with the clinical presentation to determine the disposition of these patients. The management and disposition of the mildly symptomatic or asymptomatic poisoned patient not known to have ingested highly toxic or delayed onset medications pose a challenge to the EP. Current recommendations suggest a liberal admission policy or extended observation in the ED. 4 The cost effectiveness and safety of varying periods of observation have not been previously studied. The objective of this study was to assess the feasibility of a brief observation period for minimally symptomatic or asymptomatic patients. Of the 215 patients enrolled into the study, almost half were deemed medically safe for discharge at two hours of observation. Slightly more than half the remaining patients were deemed safe at four hours. Overall, 77% of all the potentially poisoned patients were deemed medically safe for early medical clearance from the ED. None of these patients had an adverse event in the ED prior to sixhour disposition, and all were subsequently cleared at six hours. The patients who were deemed medically safe for early clearance generally had resolution of presenting symptoms, did not develop new signs or symptoms, did not have a history concerning for ingestion of long-acting medications, and did not require quantitative assessment of drug levels beyond the clearance time. In some cases, patients did continue to have some minor residual symptoms but they had clear alternative nontoxicologic explanations. Thus, in this large subset of poisoned patients whose dispositions were initially uncertain, and for whom ED observation was mandated, a brief observation period appeared both feasible and as reliable as a longer six-hour observation period. LIMITATIONS AND FUTURE QUESTIONS Several limitations of this study merit discussion. The study was designed to assess minimally symptomatic or asymptomatic patients. This study was not designed to evaluate patients with longacting medications, patients known to have ingested potentially lethal medications, or patients who ingested toxins that necessitated the determination of serum levels at specific times post-ingestion. These patients were not specifically excluded from this study so that we could determine the percentage of ED overdose patients who may

7 ACADEMIC EMERGENCY MEDICINE September 1999, Volume 6, Number be eligible for a brief observation period. Our results should not be applied to seriously ill patients or patients who have ingested drugs that obviously necessitate extended periods of observation or delayed laboratory determinations. The study did not include 24-hour long-term follow-up of the patients. It was not the intent of this study to address long-term follow-up and safety, but instead to compare outcomes at two and four hours with those at a six-hour observation period. The results of the study suggest that patients who do not develop symptoms within a two-to-four-hour period of observation and do not have a history suggestive of long-acting medications will not be likely to develop symptoms within a six-hour period of time. Both institutions have well-established relationships with the local poison control centers, which perform routine next-day patient follow-up, when indicated. Both EDs are routinely notified when patients who were seen and evaluated develop subsequent adverse events. There was no such report during the study period. However, we cannot be certain that some patients did not develop an adverse event after release from the ED. This study did not enroll consecutive patients at both institutions. The institution that enrolled a convenience sample of patients included a sample of days, evenings, nights, weekdays, and weekends in order to reduce the likelihood of selection bias. Because of the myriad possible ingestants with their infinite, variable presentations, evaluation and treatments may vary greatly among EPs. Therefore, enrollment in the study did not obligate the treating physician to manage the patient with any standard protocol, and the patient s disposition was subject to the physician s discretion. The patients in this study received generally recommended treatments. Most patients received activated charcoal and few patients received specific antidotes. The population of patients studied may be poor historians, so times post-ingestion may be unknown or unreliable, and precise disclosure of possible co-ingestants may not be possible. It is not feasible to study all individual ingestions to determine the necessary observation period for each. Emergency physicians and toxicologists can never be certain that the clinical history they obtain from patients with intentional ingestions (and possibly suicidal wishes) is totally accurate, but our study population appears representative of the typical ED patient population who would be observed and managed expectantly in the ED. These patients were generally nontoxic individuals without significant toxidromes who had a relatively high rate of attempted suicide. CONCLUSIONS Despite studying a group of patients in whom precise identification of toxins may be difficult (most did not have a toxidrome and half had suicide ideation), the patients did not develop late sequelae from unidentified ingestants, if they appeared well at presentation or two or four hours later. The results of this study suggest that some selected patients who will ultimately be medically cleared following a six-hour period of ED observation can be identified within two to four hours of presentation with a high degree of accuracy. Future studies should develop clinical criteria that can reliably identify the subset of patients who may be eligible for early medical clearance in the ED. The results of the present study should not be applied to patients who have ingested long-acting medications or poisons who present with delayed clinical sequelae. The authors acknowledge the assistance of the emergency medicine academic associates, nurses, and physicians at the participating EDs; and Marge McVey, RN, for her assistance with data entry. References 1. Litovitz TL, Klein-Schwartz W, Dyer KS, Shannon M, Lee S, Powers M annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. 1998; 16: Goldfrank LR, Flomenbaum NE, Lewin NA, Weisman RS, Howland MA, Hoffman RS. Principles of managing the poisoned or overdosed patient: an overview. In: Goldfrank LR, Flomenbaum NE, Lewin NA, Weisman RS, Howland MA, Hoffman RS (eds). Goldfrank s Toxicologic Emergencies, 6th edition. Stamford, CT: Appleton and Lange, Haddad LM, Roberts JR. A general approach to the emergency management of poisoning. In: Haddad LM, Winchester JF (eds). Clinical Management of Poisoning and Drug Overdose, 2nd edition. Philadelphia: W. B. Saunders, Eilers MA, Garrison TE. General management principles. 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Ann Emerg Med. 1984; 13: Proano L, Chiang WK, Wang RY. Calcium channel blocker overdose. Am J Emerg Med. 1995; 13: Bhatia SJ, Smith TW. Digitalis toxicity: mechanisms, di-

8 894 OVERDOSES Hollander et al. TOXICOLOGY OBSERVATION PERIODS agnosis, and management. J Cardiac Surg. 1987; 2: Smilkstein MJ, Knapp GL, Kulig KW, Rumack BH. Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. N Engl J Med. 1988; 319: Sessler CN. Theophylline toxicity: clinical features of 116 consecutive cases. Am J Med. 1990; 88: Palatnick W, Redman LW, Sitar DS, Tenenbein M. Methanol half-life during ethanol administration: implications for management of methanol poisoning. Ann Emerg Med. 1995; 26: Turk J, Morrell L, Avioli LV. Ethylene glycol intoxication. Arch Intern Med. 1986; 146: REFLECTIONS Could Someone Call Housekeeping? Aftermath of an unsuccessful resuscitation. Photograph by PATRICIA CLARKE, Rehoboth Beach, Delaware.