Abstract
Many poisoned patients may only require a period of observation after their exposure. There are limited data describing the use of observation units for managing poisoned adult and pediatric patients. We performed a retrospective review of all patients reported to the ToxIC Case Registry between January 1, 2012 and December 31, 2013. Eligible patients included those who received a bedside consultation by a medical toxicologist and whose care was provided in an observation unit, or those who were admitted under the care of a medical toxicologist in an observation unit. A total of 15,562 poisonings were reported to the registry during the study period, of which 340 (2.2 %) involved patients who were cared for in an observation unit. Of these patients, 22.1 % were 18 years of age or younger, and the remaining 77.9 % were greater than 18 years of age. The most common reason for exposure was the intentional ingestion of a pharmaceutical agent in both adult (30.2 %) and pediatric patients (36.0 %). Alcohols (ethanol) (24.9 %), opioids (20.0 %), and sedative-hypnotics (17.7 %) were the most common agent classes involved in adult patient exposures. The most common agent classes involved in pediatric exposures were antidepressants (12.0 %), anticonvulsants (10.7 %), and envenomations (10.7 %). In adult patients, the most common signs and symptoms involved the nervous system (52.0 %), a toxidrome (17.0 %), or a major vital sign abnormality (14.7 %). In pediatric patients, the most common signs and symptoms involved the nervous system (53.3 %), a toxidrome (21.3 %), or a major vital sign abnormality (17.3 %). The results of this study demonstrate that a wide variety of poisoned patients have been cared for in an observation unit in consultation with a board-certified medical toxicologist. Patterns for the reasons for exposure, agents responsible for the exposure, and toxicological treatments will continue to evolve. Further study is needed to identify better those poisoned patients who can be appropriately managed in an observation unit.
Keywords: Medical toxicology, Observation units, Overdose, Poisonings, Registry, Toxicology
Introduction
In 2012, approximately 27.5 % of the 613,412 human poisonings reported to poison centers and managed in healthcare facilities across the USA caused toxicity serious enough to necessitate admission to a hospital [1]. However, many poisoned patients may only require a period of observation after their exposure due to abnormal vital signs, change in mental status, need for toxicological treatment, or if there is potential for delayed toxicity. Observation units provide an alternative for clinicians in which to render care to these patients.
An observation unit has been defined as an area of the hospital, typically adjacent to or located within the emergency department, where patients can be monitored clinically and receive additional therapies and/or diagnostic tests following an emergency department evaluation [2]. Most observation units are managed by emergency department personnel [3, 4]. Usually, patients stay for less than 24 h before being discharged home or admitted for psychiatric treatment [5].
For over two decades, observation units have been used to manage patients with specific diagnoses, including poisoned patients [2, 6]. In 2007, a national survey revealed that about one third of hospitals delivered care in an observation unit [7]. Multiple studies have demonstrated that care rendered in observation units is equal or better in quality and lower in cost than inpatient care for select medical conditions [8–10].
Unfortunately, there are limited data describing the use of observation units for managing poisoned adult and pediatric patients [11–14]. Knowledge of the reasons for exposure, substances ingested, associated signs and symptoms, and toxicological treatment provided for patients cared for in an observation unit would be valuable to clinicians. Recent trends regarding the use of observation units to manage poisoned patients are also important because of the large number of toxicological patients who are treated annually in emergency departments throughout the USA and escalating healthcare costs. For this descriptive study, we sought to determine the following for poisoned patients cared for in an observation unit and whose evaluation also included consultation by a board-certified medical toxicologist: (1) reasons for exposure, (2) substances or toxins exposed to, (3) associated signs and symptoms, and (4) toxicological treatment provided.
Methods
Study Sites
The Toxicology Investigators Consortium (ToxIC) Case Registry was established in 2010 by the American College of Medical Toxicology (ACMT) to serve as a prospective toxico-surveillance system [15]. The registry prospectively gathers all cases managed at the bedside by medical toxicologists in its 41 participating sites from Australia, Canada, Israel, and 22 states across the USA. The majority of the contributing sites are university-affiliated academic institutions, including 18 of the 30 Medical Toxicology Fellowship training programs. At each participating site, case entries are performed online and stored in a password-protected database that is maintained by the ACMT.
A detailed description of the registry has been previously published [15]. Briefly, the registry database allows for identification, extraction, and pooling of information on toxicological exposures among participating sites. It also provides the most likely etiology of patients’ symptoms. The registry has been approved to function without restriction by the Western Institutional Review board, as long as all patient data are de-identified and there are no patient interventions as a result of being in the registry. Sites contribute cases to the registry with the consent or waiver of their specific institutional review board. Contributors agree to enter all eligible cases that may be employed for research purposes as part of participating in the registry.
Patients
We identified all cases, entered prospectively into the registry between January 1, 2012 and December 31, 2013. Although the registry was established in 2010, it only began tracking placement of poisoned patients into observation units on January 1, 2012. Eligible patients were identified using the following search criteria: those who received a bedside consultation by a medical toxicologist and whose care was provided in an observation unit, or those who were admitted under the care of a medical toxicologist in an observation unit. For this study, an “observation unit” was defined as an area of the hospital, adjacent to or located within in the emergency department, where patients could be monitored clinically and receive additional therapies and/or diagnostic tests following an emergency department evaluation [2]. Toxicological exposures were confirmed by the performance of a detailed, bedside history, and physical examination by a board-certified medical toxicologist. Ancillary diagnostic tests (e.g., serum drug concentration, urine drug screens) were performed when necessary to aid in confirming toxicological exposures. Data output from the registry was sorted by patient age, and information entered into a database. To ensure study eligibility, each case was reviewed by the authors (BJ, MV, LO).
Data Collection
This retrospective, descriptive study analyzed all eligible cases to explore the reasons for exposure, substances ingested, associated signs and symptoms, and toxicological treatment provided. No chemicals, medications, substances, or environmental/occupational exposures were excluded. Demographic information and clinical data were tabulated for patients including (1) age group and gender; (2) circumstances and reasons for exposure; (3) all substances or toxins to which each patient was exposed, as determined by the medical toxicologist; (4) associated signs and symptoms; and (5) toxicological treatment rendered.
Results
A total of 15,562 poisonings were reported to the registry during the study period, of which 340 (2.2 %) involved patients who were cared for in an observation unit. Of these patients, 22.1 % were 18 years of age or younger, and the remaining 77.9 % were greater than 18 years of age. Of the 75 pediatric cases, 46.7 % were male, whereas 60.4 % of the 265 adult cases were male. Multiple (≥2) agent exposures were recorded in 27.5 % of adult cases and 21.3 % of pediatric cases. The median number of drugs involved in multiple exposure cases was 2 (range, 2–6) in adult patients and 2 (range, 2–4) in pediatric patients. Only three out of the 340 cases were reported by participating international sites during the study period. No deaths were reported in either cohort of patients.
Reasons for Exposure
The most common reason for exposure was the intentional ingestion of a pharmaceutical agent in both adult (30.2 %) and pediatric patients (36.0 %). A higher percentage of pediatric patients (30.7 %) was exposed unintentionally to a pharmaceutical agent compared to 9.4 % of adult patients. Withdrawal states from ethanol, opioids, and sedative-hypnotics (11.3 %); the abuse of illicit, prescription, and over-the-counter drugs (16.6 %); and ethanol abuse (16.6 %) were all common reasons for exposure in patients 18 years or older.
Adverse drug events (medication error resulting in harm) and adverse drug reactions (undesirable effect of medication used in a normal dose) accounted for 9.4 and 6.7 % of exposures in adult and pediatric patients, respectively. Envenomation by a snake, scorpion, or spider was more common in pediatric patients (10.7 %) compared with adult patients (4.2 %). The reasons for exposure for adult and pediatric patients are provided in Table 1.
Table 1.
Reasons for exposure
| Adult patients (>18 years) (n = 265) | Pediatric patients (≤18 years) (n = 75) | ||||
|---|---|---|---|---|---|
| Reason | Number | Percent | Reason | Number | Percent |
| Intentional—pharmaceutical | 80 | 30.2 | Intentional—pharmaceutical | 27 | 36.0 |
| ETOH Abuse | 44 | 16.6 | Unintentional—pharmaceutical | 23 | 30.7 |
| Drug abuse—illicit | 28 | 10.6 | Snake | 5 | 6.7 |
| Unintentional—pharmaceutical | 25 | 9.4 | Unintentional—non-pharmaceutical | 4 | 5.3 |
| ADR | 17 | 6.4 | ADR | 3 | 4.0 |
| Withdrawal—ETOH | 16 | 6.0 | Intentional—non-pharmaceutical | 2 | 2.7 |
| Drug abuse—prescription | 15 | 5.7 | Drug abuse—illicit | 2 | 2.7 |
| Withdrawal—opioids | 13 | 4.9 | ETOH abuse | 2 | 2.7 |
| Intentional—non-pharmaceutical | 11 | 4.2 | ADE | 2 | 2.7 |
| ADE | 8 | 3.0 | Spider | 2 | 2.7 |
| Snake | 8 | 3.0 | Drug abuse—prescription | 1 | 1.3 |
| Unknown | 7 | 2.6 | Scorpion | 1 | 1.3 |
| Interpretation of lab data | 6 | 2.3 | Organ system dysfunction | 1 | 1.3 |
| Unintentional—non-pharmaceutical | 3 | 1.1 | Unknown | 1 | 1.3 |
| Organ system dysfunction | 3 | 1.1 | |||
| Scorpion | 2 | 0.8 | |||
| Drug abuse—OTC | 1 | 0.4 | |||
| Withdrawal—sedative-hypnotic | 1 | 0.4 | |||
| Spider | 1 | 0.4 | |||
| Marine/fish | 1 | 0.4 | |||
| Occupational evaluation | 1 | 0.4 | |||
Patients may have had more than one reason for exposure; thus, percentages do not add up to 100 %
Substance/Toxin Exposures
Alcohols (ethanol) (24.9 %), opioids (20.0 %), and sedative-hypnotics (17.7 %) were the most common agent classes involved in adult patient exposures. These agent classes accounted for 2.7, 2.7, and 9.3 % of pediatric exposures, respectively. The most common agent classes involved in pediatric exposures were antidepressants (12.0 %), anticonvulsants (10.7 %), and envenomations (10.7 %). For adult patients exposed to alcohol, it was the only substance which they were exposed to in 69.7 % of alcohol-related cases, including alcohol withdrawal. In 8.7 % of patients older than 18 years, it was unknown to which agent class they were exposed, compared with 13.3 % of patients ≤18 years. The agent classes involved in adult and pediatric exposures are provided in Table 2. The most common agents reported for the top three substance/toxin classes for adult and pediatric patients are listed in Table 3.
Table 2.
Agent classes involved in exposures
| Adult patients (>18 years) (n = 265) | Pediatric patients (≤18 years) (n = 75) | ||||
|---|---|---|---|---|---|
| Substance/toxin class | Number | Percent | Substance/toxin class | Number | Percent |
| Alcohols (ethanol) | 66 | 24.9 | Unknown | 10 | 13.3 |
| Opioids | 53 | 20.0 | Antidepressants | 9 | 12.0 |
| Sedative-hypnotics | 47 | 17.7 | Anticonvulsants | 8 | 10.7 |
| Unknown | 23 | 8.7 | Envenomation | 8 | 10.7 |
| Analgesics | 22 | 8.3 | Analgesics | 7 | 9.3 |
| Anticholinergic/antihistamines | 20 | 7.5 | Sedative-hypnotics | 7 | 9.3 |
| Anticonvulsants | 19 | 7.2 | Anticholinergic/antihistamines | 6 | 8.0 |
| Antidepressants | 15 | 5.7 | Cardiovascular | 6 | 8.0 |
| Antipsychotics | 15 | 5.7 | Sympathomimetic | 5 | 6.7 |
| Cardiovascular | 12 | 4.5 | Antipsychotics | 3 | 4.0 |
| Envenomation | 12 | 4.5 | Hydrocarbons | 3 | 4.0 |
| Sympathomimetic | 12 | 4.9 | Psychoactive | 3 | 4.0 |
| Psychoactive | 7 | 2.6 | Alcohols (ethanol) | 2 | 2.7 |
| Diabetic meds | 6 | 2.3 | Opioids | 2 | 2.7 |
| Lithium | 6 | 2.3 | Alcohols (toxic) | 1 | 1.3 |
| Other—non-pharm | 6 | 2.3 | Anesthetics | 1 | 1.3 |
| Anticoagulant | 4 | 1.5 | Antimicrobials | 1 | 1.3 |
| Alcohols (toxic) | 2 | 0.8 | Cough and cold | 1 | 1.3 |
| Herbals | 2 | 0.8 | Diabetic meds | 1 | 1.3 |
| Metals/metalloids/iron | 2 | 0.8 | Herbals | 1 | 1.3 |
| Plants/fungi | 2 | 0.8 | Household | 1 | 1.3 |
| Other—pharmaceutical | 2 | 0.8 | |||
| Anesthetics | 1 | 0.4 | |||
| Antimicrobials | 1 | 0.4 | |||
| Chemotherapeutic | 1 | 0.4 | |||
| Cough and cold | 1 | 0.4 | |||
| Endocrine/hormones/steroids | 1 | 0.4 | |||
| Gastrointestinal | 1 | 0.4 | |||
| Household | 1 | 0.4 | |||
Patients may have been exposed to two or more classes of substances or toxins; thus, the percentages do not add up to 100 %
Table 3.
Most common agents reported in the top 3 substances/toxin classes for adult and pediatric patients
| Adult patients (>18 years) (n = 265) | Pediatric patients (≤18 years) (n = 75) | ||||
|---|---|---|---|---|---|
| Most common agents | Number | Percent | Most common agents | Number | Percent |
| Alcohols | 66 | 24.9 | Antidepressants | 9 | 12.0 |
| Ethanol | 66 | 24.9 | Citalopram | 4 | 5.3 |
| Bupropion | 2 | 2.7 | |||
| Fluoxetine | 2 | 2.7 | |||
| Fluvoxamine | 1 | 1.3 | |||
| Sertraline | 1 | 1.3 | |||
| Venlafaxine | 1 | 1.3 | |||
| Opioids | 51 | 19.2 | Anticonvulsants | 8 | 10.7 |
| Heroin | 14 | 5.2 | Carbamazepine | 3 | 4.0 |
| Oxycodone | 7 | 2.6 | Lamotrigine | 3 | 4.0 |
| Dextromethorphan | 5 | 1.9 | Topiramate | 1 | 1.3 |
| Valproate | 1 | 1.3 | |||
| Sedative-hypnotics | 47 | 17.7 | Envenomation | 8 | 10.7 |
| Clonazepam | 13 | 4.9 | Agkistrodon | 2 | 2.7 |
| Alprazolam | 10 | 3.8 | Crotalus | 2 | 2.7 |
| Carisoprodol | 4 | 1.5 | Loxosceles | 2 | 2.7 |
| Lorazepam | 4 | 1.5 | Scorpion (unknown species) | 1 | 1.3 |
| Zolpidem | 4 | 1.5 | Snake (unknown species) | 1 | 1.3 |
Agents are listed in order of declining frequency. Percentages do not add up to 100 % since only the top 3 substance/toxin classes are represented
Signs and Symptoms
Adult and pediatric patients were noted to have a variety of signs and symptoms as recorded by the medical toxicologist (Table 4). In adult patients, the most common signs and symptoms involved the nervous system (52.0 %), a toxidrome (17.0 %), or a major vital sign abnormality (14.7 %). Eighty adult patients (30.2 %) were asymptomatic, whereas 27.5 % had signs or symptoms involving two or more organ systems. In pediatric patients, the most common signs and symptoms involved the nervous system (53.3 %), a toxidrome (21.3 %), or a major vital sign abnormality (17.3 %). Twenty-four (32.0 %) pediatric patients were asymptomatic, whereas 25.3 % had signs or symptoms involving two or more organ systems.
Table 4.
Signs and symptoms in adult and pediatric patients as recorded by the medical toxicologist
| Adult patients (>18 years) (n = 265) | Pediatric patients (≤18 years) (n = 75) | ||||
|---|---|---|---|---|---|
| Organ system | Number | Percent | Organ system | Number | Percent |
| Nervous system | 138 | 52.0 | Nervous system | 40 | 53.3 |
| Coma/central nervous system depression | 59 | 22.3 | Coma/central nervous system depression | 18 | 24.0 |
| Delirium/toxic psychosis | 38 | 14.3 | Agitation | 10 | 13.3 |
| Hyperreflexia/myoclonus/clonus/tremor | 12 | 4.5 | Hyperreflexia/myoclonus/clonus/tremor | 4 | 5.3 |
| Agitation | 10 | 3.8 | Delirium/toxic psychosis | 3 | 4.0 |
| Seizures | 7 | 2.6 | Hallucinations | 2 | 2.7 |
| Hallucinations | 4 | 1.5 | Extrapyramidal symptoms/dystonia/rigidity | 1 | 1.3 |
| Numbness/paresthesias | 3 | 1.1 | Seizures | 1 | 1.3 |
| Weakness/paralysis | 3 | 1.1 | Weakness/paralysis | 1 | 1.3 |
| Extrapyramidal symptoms/dystonia/rigidity | 1 | 0.4 | |||
| Peripheral Neuropathy | 1 | 0.4 | |||
| Toxidrome | 45 | 17.0 | Toxidrome | 16 | 21.3 |
| Sedative-hypnotic | 28 | 10.6 | Sedative-hypnotic | 9 | 12.0 |
| Anticholinergic | 6 | 2.3 | Anticholinergic | 3 | 4.0 |
| Serotonin syndrome | 5 | 1.9 | Opioid | 1 | 1.3 |
| Opioid | 3 | 1.1 | Serotonin syndrome | 1 | 1.3 |
| Cholinergic | 1 | 0.4 | Sympatholytic | 1 | 1.3 |
| Sympathomimetic syndrome | 1 | 0.4 | Sympathomimetic syndrome | 1 | 1.3 |
| Washout syndrome | 1 | 0.4 | |||
| Major vital sign abnormalities | 39 | 14.7 | Major vital sign abnormalities | 13 | 17.3 |
| Hypotension (SBP < 80) | 13 | 4.9 | Tachycardia (P > 140) | 6 | 8.0 |
| Hypertension (SBP > 200 and/or DBP > 120) | 9 | 3.4 | Hypotension (SBP < 80) | 5 | 6.7 |
| Tachycardia (P > 140) | 8 | 3.0 | Hypertension (SBP > 200 and/or DBP > 120) | 1 | 1.3 |
| Bradycardia (P < 50) | 8 | 3.0 | Bradycardia (P < 50) | 1 | 1.3 |
| Bradypnea (R < 10) | 1 | 0.4 | |||
| Metabolic | 22 | 7.9 | Dermatologic | 6 | 8.0 |
| Metabolic acidosis (pH < 7.2) | 10 | 3.8 | Rash | 2 | 2.7 |
| Hypoglycemia (BG < 50) | 5 | 1.9 | Angioedema | 2 | 2.7 |
| Elevated anion Gap (AG > 20) | 5 | 1.9 | Blisters | 2 | 2.7 |
| Elevated osmolal gap (OG > 20) | 2 | 0.8 | |||
| Gastrointestinal/hepatic | 18 | 6.8 | Metabolic | 5 | 6.7 |
| Hepatotoxicity (AST > 1000) | 14 | 5.3 | Metabolic acidosis (pH < 7.2) | 3 | 4.0 |
| Gastrointestinal bleed | 3 | 1.1 | Hypoglycemia (BG < 50) | 1 | 1.3 |
| Pancreatitis (lipase > 100) | 1 | 0.4 | Elevated anion gap (AG > 20) | 1 | 1.3 |
| Renal/muscle | 19 | 7.2 | Pulmonary | 4 | 5.3 |
| Acute kidney injury (creat > 2.0) | 13 | 4.9 | Aspiration pneumonitis | 2 | 2.7 |
| Rhabdomyolysis (CPK > 1000) | 4 | 1.5 | Respiratory depression | 2 | 2.7 |
| Hematologic | 13 | 4.9 | Cardiovascular | 1 | 1.3 |
| Significant leukocytosis (WBC > 20,000) | 6 | 2.3 | Prolonged QTc (≥500 ms) | 1 | 1.3 |
| Thrombocytopenia (PLTs < 20,000) | 4 | 1.5 | |||
| Significant coagulopathy (PT > 15) | 2 | 0.8 | |||
| Hemolysis (Hgb < 10) | 1 | 0.4 | |||
| Pulmonary | 10 | 3.8 | Hematologic | 1 | 1.3 |
| Aspiration pneumonitis | 6 | 2.3 | Significant leukocytosis (WBC > 20,000) | 1 | 1.3 |
| Respiratory depression | 3 | 1.1 | |||
| Acute lung injury/acute respiratory distress syndrome | 1 | 0.4 | |||
| Cardiovascular | 10 | 3.8 | |||
| Prolonged QTc (≥500 ms) | 8 | 3.0 | |||
| Ventricular dysrhythmias | 1 | 0.4 | |||
| Prolonged QRS (≥120 ms) | 1 | 0.4 | |||
| Dermatologic | 9 | 3.4 | |||
| Rash | 4 | 1.5 | |||
| Blisters | 3 | 1.1 | |||
| Angioedema | 2 | 0.8 | |||
| No signs or symptoms | 80 | 30.2 | No signs or symptoms | 24 | 32.0 |
| Two or more organ systems affected | 73 | 27.5 | Two or more organ systems affected | 19 | 25.3 |
Signs and symptoms are categorized by organ system and declining order of frequency. Percentages were calculated based on the number of adult or pediatric patients. Several patients may have had two or more organ systems affected; thus, the percentages do not add up to 100 %
Toxicological Treatments
A large percentage of adult (44.9 %) and pediatric (53.3 %) patients received no toxicological treatment during their observation stay (Table 5). Antidotes were administered to 39.2 % of adult patients and 20.0 % of pediatric patients. Pharmacologic support was provided to 23.8 and 18.7 % of adult and pediatric patients, respectively. Non-pharmacologic support was provided to 18.1 and 18.7 % of adult and pediatric patients, respectively. Twenty-three percent of adult patients received two or more toxicological treatments, and 17.3 % of pediatric patients received two or more toxicological treatments during their stay in an observation unit. Eight of the 13 (61.5 %) patients with snake envenomation received Crotalidae Polyvalent Immune Fab (Ovine), with no apparent difference in the administration of antivenom between adult (5/8, 62.5 %) and pediatric (3/5, 60.0 %) patients. Ten out of the three hundred and forty (2.9 %) patients required intervention for life-threatening conditions and are described in Table 6.
Table 5.
Treatments reported to have been used in poisoned patients cared for in an observation unit
| Adult patients (>18 years) (n = 265) | Pediatric patients (≤18 years) (n = 75) | ||||
|---|---|---|---|---|---|
| Treatment | Number | Percent | Treatment | Number | Percent |
| Antidotes | 104 | 39.2 | Antidotes | 15 | 20.0 |
| Naloxone/nalmefene | 31 | 11.7 | Naloxone/nalmefene | 3 | 4.0 |
| Physostigmine | 17 | 6.4 | Flumazenil | 3 | 4.0 |
| Flumazenil | 13 | 4.9 | N-acetylcysteine | 3 | 4.0 |
| Thiamine | 13 | 4.9 | Sodium bicarbonate | 2 | 2.7 |
| N-acetylcysteine | 9 | 3.4 | Physostigmine | 2 | 2.7 |
| Folate | 6 | 2.3 | Glucagon | 1 | 1.3 |
| Sodium bicarbonate | 4 | 1.5 | Fomepizole | 1 | 1.3 |
| Octreotide | 3 | 1.1 | |||
| Fomepizole | 2 | 0.8 | |||
| Carnitine | 2 | 0.8 | |||
| Atropine | 1 | 0.4 | |||
| Vitamin K | 1 | 0.4 | |||
| Pharmacologic support | 63 | 23.8 | Pharmacologic support | 14 | 18.7 |
| Benzodiazepines | 25 | 9.4 | Benzodiazepines | 8 | 10.7 |
| Antipsychotics | 11 | 4.2 | Opioids | 2 | 2.7 |
| Opioids | 5 | 1.9 | Antiemetics | 1 | 1.3 |
| Vasopressors | 3 | 1.1 | Steroids | 1 | 1.3 |
| Glucose | 3 | 1.1 | Vasopressors | 1 | 1.3 |
| Anticonvulsants | 3 | 1.1 | Antihistamines | 1 | 1.3 |
| Steroids | 2 | 0.8 | |||
| Antihypertensives | 2 | 0.8 | |||
| Buprenorphine | 2 | 0.8 | |||
| Clonidine | 2 | 0.8 | |||
| Albuterol | 1 | 0.4 | |||
| Magnesium | 1 | 0.4 | |||
| Folinic acid | 1 | 0.4 | |||
| Hydroxyzine | 1 | 0.4 | |||
| Phenobarbitol | 1 | 0.4 | |||
| Non-pharmacologic support | 48 | 18.1 | Non-pharmacologic support | 14 | 18.7 |
| IV fluids | 41 | 15.5 | IV fluids | 13 | 17.3 |
| Intubation | 4 | 1.5 | EGD | 1 | 1.3 |
| CPR | 2 | 0.8 | |||
| Wound care | 1 | 0.4 | |||
| Decontamination | 6 | 2.3 | Decontamination | 5 | 6.7 |
| Activated charcoal | 4 | 1.5 | Activated charcoal | 5 | 6.7 |
| Whole bowel irrigation | 1 | 0.4 | |||
| Irrigation | 1 | 0.4 | |||
| Antivenom | 5 | 1.9 | Antivenom | 3 | 4.0 |
| Crotalidae Polyvalent Immune Fab (Ovine) | 5 | 1.9 | Crotalidae Polyvalent Immune Fab (Ovine) | 3 | 4.0 |
| Elimination | 4 | 1.5 | |||
| Multi-dose activated charcoal | 2 | 0.8 | |||
| Urinary alkalinization | 2 | 0.8 | |||
| No treatment received | 119 | 44.9 | No treatment received | 40 | 53.3 |
| Received two or more treatments | 61 | 23.0 | Received two or more treatments | 13 | 17.3 |
Treatments are listed in order of declining frequency. Patients may have received more than one treatment; thus, percentages do not add up to 100 %
Table 6.
Case characteristics in which an intervention was necessary for a life-threatening condition
| Patient (sex, age) | Reason(s) for exposure | Agent(s) | Signs and symptoms | Treatment(s) |
|---|---|---|---|---|
| Male, 34 years | Unintentional—pharmaceutical | Clonidine | Bradycardia, coma/CNS depression | Atropine |
| Female, 21 years | Adverse drug event, (medication error resulting in harm) | Bupivacaine | Seizures | Intubation |
| Male, 23 years | Drug abuse—prescription | Methadone | Aspiration pneumonitis, coma/CNS depression, delirium/toxic psychosis, acute kidney injury | Intubation, naloxone/nalmefene |
| Male, 64 years | Withdrawal—EtOH | Ethanol | Unknown | Intubation, antipsychotics, benzodiazepines, phenobarbital, clonidine |
| Female, 47 years | Intentional—pharmaceutical | Tramadol, hydralazine valproate, hydroxyzine | Ventricular dysrhythmias, prolonged QRS, prolonged QTc, coma/CNS depression, seizures, metabolic acidosis, elevated anion gap | CPR, intubation, activated charcoal |
| Male, 27 years | Drug abuse—illicit | Heroin | Opioid toxidrome | CPR, naloxone/nalmefene |
| Female, 20 years | Intentional—pharmaceutical | Methadone, clonazepam | Opioid toxidrome, hypotension, respiratory depression, coma/CNS depression, metabolic acidosis, acute kidney injury, rhabdomyolysis | Vasopressors, IV fluids, sodium bicarbonate |
| Female, 64 years | Intentional—pharmaceutical | Amlodipine, benazepril, metformin | Hypotension, bradycardia | Vasopressors, IV fluids |
| Male, 48 years | Intentional—pharmaceutical, EtOH abuse | Ethanol, lithium, clonazepam | Sedative-hypnotic, delirium/toxic psychosis | Vasopressors, anticonvulsants |
| Male, 17 years | Adverse drug reaction (undesirable effect of a medication used in a normal dose) | Septocaine | Angioedema | Vasopressors, opioids, steroids, antihistamines |
Discussion
Observation units, whether they are located within or adjacent to an emergency department, offer clinicians an alternative in which to render care to patients. Their use has become increasingly popular due to their ability to decompress emergency departments and inpatient beds and provide cost-effective, high-quality care [2]. In many ways, poisoned patients are suitable candidates for observation management: (1) the toxicodynamic properties of most toxicants are fairly predictable [11], (2) patients with unknown ingestions or who have ingested a substance with sustained-release properties can be monitored for delayed toxicity [16], (3) the vast majority of these patients are likely to be discharged within 24 h [11, 13, 14, 17], (4) only a small percentage of poisoned patients fail observation and require inpatient admission [11–14, 17], and (5) these patients can receive support to address emotional and psychiatric issues [16].
While the number of dedicated observation units in hospitals is growing across the USA [18, 19], very few studies have exclusively evaluated the utilization or experience of observation units for poisoned patients [11–14]. Findings from these studies, while useful, are limited for several reasons. First, all of the studies were performed at a single institution [11–14]. Second, two of the studies focused only on pediatric patients [11, 14]. Third, none of the studies evaluated the reasons for exposure, fully delineated the classes of substances or toxins that patients were exposed to, fully examined associated signs and symptoms, or provided information on toxicological treatments administered to patients [11–14].
There were some surprising findings from this study. The first is the variability of the use of certain antidotes in poisoned patients managed in an observation unit. As an example, we found that physostigmine was used in 19 cases; however, only nine patients were recorded as having an anticholinergic toxidrome. Further analysis revealed that one participating site was responsible for administering physostigmine in 94.7 % of cases.
The second finding relates to those instances in which the medical toxicologist could not determine which substance or toxin class a patient had been exposed to. These cases were placed in an “unknown” category and accounted for 8.7 % of adult and 13.3 % of pediatric patients (Table 2). None of these patients required intervention for a life-threatening condition. While the percentage of these “unknown” cases seems disproportionately high, Callelo et al. reported that the substance or toxin class could not be determined in 6.1 % of pediatric patients managed in an observation unit [11]. Considering that it is not always possible to deduce the type of exposure for poisoned patients, some patients with an “unknown” exposure may be appropriate for managing in an observation unit.
The third and most concerning findings are those patients who required intervention for life-threatening conditions (Table 6). The potential for deterioration in a poisoned patient’s clinical condition is always a concern; however, comprehensive data regarding the safety of the use of observation units for the treatment of poisoned patients is lacking. Previous studies have reported an unplanned hospitalization rate for poisoned patients managed in an observation unit ranging from 2.2 to 5.9 % [11, 12, 14].
While this study did not directly address patients who failed their observation stay, we did identify several cases (2.9 %) that required intervention for life-threatening conditions. Because of the descriptive nature of this study, it was not possible to determine which variables (e.g., toxin characteristics, evidence of end-organ toxicity, preexisting medical conditions, physical dependency, amount ingested, or observation unit capabilities) may have contributed to the clinical deterioration in this subset of patients. Clinical deterioration or unplanned hospitalization might be unpredictable for a small percentage of poisoned patients cared for in an observation unit. In other words, some poisoned patients will become more ill while being managed in an observation unit. However, to mitigate the risk for clinical deterioration, it is important for physicians to consider the aforementioned variables before placing a poisoned patient in an observation unit.
The results of our study and others [11, 12] suggest that observation units may be underutilized for managing poisoned patients. However, our data may be skewed toward more serious poisonings since it is comprised of cases that involved the consultation of a board-certified medical toxicologist. Additionally, not all cases of patients cared for in an observation unit may have been entered into the ToxIC Registry by participating sites during the study period.
Finally, this study provides a unique perspective on recent trends about the use of observation units for poisoned patients and whose care involved consultation by a board-certified medical toxicologist. Additionally, it provides a snapshot of the reasons for exposure, classes of substances or toxins that a patient was exposed to, associated signs and symptoms, and toxicological treatment provided. However, readers must be cautioned that the results of this study were generated from “top-level” data gathered from the registry. Individual patient charts from participating sites were not studied. Therefore, we were unable to determine how patients were selected for placement into an observation unit, which treatment protocols were in place, and what resources were available for patient care. Further study is necessary to help develop predictive factors and clinical guidelines to better identify toxicological patients that can be safely managed in an observation unit.
Limitations
Our study has several important limitations. This is a descriptive study and is therefore limited in its scope. The generalizability of the results may not be applicable to many healthcare facilities since the ToxIC Registry primarily captures cases from academic and tertiary care referral centers. Data may represent poisonings caused by agents that clinicians may not be comfortable managing in an observation unit without consultation from a medical toxicologist. Outcomes such as unplanned inpatient admission, length of stay, and adverse rate event were not directly evaluated. Patients were not followed up after discharge from the observation unit. Finally, error may have been introduced into the data since the registry relies on individual sites to report all of their cases.
Conclusions
The results of this study demonstrate that a wide variety of poisoned patients has been cared for in an observation unit in consultation with a board-certified medical toxicologist. Patterns for the reasons for exposure, agents responsible for the exposure, and toxicological treatments will continue to evolve. Further study is needed to help better identify those poisoned patients who can be appropriately managed in an observation unit.
References
- 1.Mowry JB, Spyker DA, Cantilena LR, Bailey JE, Ford M. 2012 Annual report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 30th Annual Report. Clin Toxicol. 2013;51:949–1229. doi: 10.3109/15563650.2013.863906. [DOI] [PubMed] [Google Scholar]
- 2.Komindr A, Baugh CW, Grossman SA, Bohan SJ. Key operational characteristics in emergency department observation units: a comparative study between sites in the United States and Asia. Int J Emerg Med. 2014;7:6. doi: 10.1186/1865-1380-7-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Yealy DM, De Hart DA, Ellis G, Wolfson AB. A survey of observation units in the United States. Am J Emerg Med. 1989;7(6):576–580. doi: 10.1016/0735-6757(89)90277-5. [DOI] [PubMed] [Google Scholar]
- 4.Brillman J, Mathers-Dunbar L, Graff L, Joseph T, Leikin JB, Schultz C, et al. Management of observation units. Ann Emerg Med. 1995;25(6):823–830. doi: 10.1016/S0196-0644(95)70215-6. [DOI] [PubMed] [Google Scholar]
- 5.Ross MA, Graff LG., 4th Principles of observation medicine. Emerg Med Clin North Am. 2001;19(1):1–17. doi: 10.1016/S0733-8627(05)70165-6. [DOI] [PubMed] [Google Scholar]
- 6.Leikin JB. The uprooting of observational units from emergency departments: opportunity lost for emergency medicine? Am J Emerg Med. 1988;6(1):49–51. doi: 10.1016/0735-6757(88)90206-9. [DOI] [PubMed] [Google Scholar]
- 7.Niska R, Bhuiya F, Xu J. National Hospital Ambulatory Medical Care Survey: 2007 emergency department summary. Natl Health Stat Rep. 2010. Aug 6: 26; 1–31. [PubMed]
- 8.Ross MA, Compton S, Medado P, Fitzgerald M, Kilanowski P, O’Neil BJ. An emergency department diagnostic protocol for patients with transient ischemic attack: a randomized controlled trial. Ann Emerg Med. 2007;50(2):109–19. doi: 10.1016/j.annemergmed.2007.03.008. [DOI] [PubMed] [Google Scholar]
- 9.Jagminas L, Partridge R. A comparison of emergency department versus inhospital chest pain observation units. Am J Emerg Med. 2005;23(2):111–3. doi: 10.1016/j.ajem.2004.03.009. [DOI] [PubMed] [Google Scholar]
- 10.McDermott MF, Murphy DG, Zalenski RJ, Rydman RJ, McCarren M, Marder D, et al. A comparison between emergency diagnostic and treatment unit and inpatient care in the management of acute asthma. Arch Intern Med. 1997;157(18):2055–62. doi: 10.1001/archinte.1997.00440390041006. [DOI] [PubMed] [Google Scholar]
- 11.Calello DP, Alpern ER, McDaniel-Yakscoe M, Garrett BL, Shaw KN, Osterhoudt KC. Observation unit experience for pediatric poison exposures. J Med Toxicol. 2009;5(1):15–19. doi: 10.1007/BF03160975. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Dribben W, Welch J, Dunn D, Kirk M. The utilization of emergency department observation units for the poisoned patient. Clin Toxicol. 1999;37(5):583–675. [Google Scholar]
- 13.Gummin DD, Butler JR, Roberts RR, Erickson TB. Utilization of an emergency department observation unit for acute intoxications. Clin Toxicol. 1999;37(5):583–675. [Google Scholar]
- 14.Plumb J, Dudley NC, Herman BE, Kadish HA. Utilization of a pediatric observation unit for toxicologic ingestions. Pediatr Emerg Care. 2012;28(11):1169–1172. doi: 10.1097/PEC.0b013e3182717329. [DOI] [PubMed] [Google Scholar]
- 15.Wax PM, Kleinschmidt KC, Brent J. The Toxicology Investigators Consortium (ToxIC) Registry. J Med Toxicol. 2011;7:259–265. doi: 10.1007/s13181-011-0177-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Lemke T, Wang R. Emergency department observation for toxicologic exposures. Emerg Observation Med. 2001;19(1):155–167. doi: 10.1016/s0733-8627(05)70173-5. [DOI] [PubMed] [Google Scholar]
- 17.Zebrack M, Katish H, Nelson D. The pediatric hybrid observation unit: an analysis of 6477 consecutive patient encounters. Pediatr. 2005 doi: 10.1542/peds.2004-0391. [DOI] [PubMed] [Google Scholar]
- 18.Mace SE, Graff L, Mikhail M, Ross M. A national survey of observation units in the United States. Am J Emerg Med. 2003;21(7):529–533. doi: 10.1016/j.ajem.2003.08.012. [DOI] [PubMed] [Google Scholar]
- 19.Baugh CW, Venkatesh AK, Hilton JA, Samuel PA, Schuur JD, Bohan JS. Making greater use of dedicated hospital observation units for many short-stay patients could save $3.1 billion a year. Health Aff. 2012;31(10):2314–2323. doi: 10.1377/hlthaff.2011.0926. [DOI] [PubMed] [Google Scholar]