TOXIC REVIEW
From Managing Medical Emergencies, sponsored by the Emergency Department at Dartmouth-Hitchcock Medical
Center, and the New Hampshire Chapter of the American College of Emergency Physicians
| ALCOHOLIC TOXINS —David W. Nierenberg, MD, Edward Tulloch Krumm Professor of Medicine and Pharmacology/Toxicology,
and Section Chief, Clinical Pharmacology, and Senior Associated Dean for Medical Education,
Dartmouth-Hitchcock Medical Center, Lebanon, NH
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| Methanol ingestion: signs and symptoms—central nervous system (CNS) depression and intoxication, rarely tachycardia
and hypotension, sometimes hypothermia (if patient loses consciousness in cold environment); visual
problems 12 to 24 hr after ingestion; laboratory tests—obtain electrolyte level and calculate anion gap; large anion
gap indication of metabolic acidosis; ingestion of methanol or ethylene glycol or acetylsalicylic acid (aspirin) overdose
most common causes, lactic acidosis or diabetic ketoacidosis less common; obtain serum urea nitrogen
(BUN)/creatinine ratio to determine effect on renal function; check blood glucose and ethanol level (ethanol natural
antidote to methanol); obtain arterial blood gases (ABG); measure methanol and osmolarity if possible; gas chromatography
required to measure methanol level (turnaround time 3-4 hr); osmolarity measured by freezing-point
depression (turnaround time 20 min); protocol—stabilize patient; usually too late for gastric lavage and activated
charcoal (methanol and ethylene glycol absorbed within 30 min of ingestion); perform history and physical examination;
perform laboratory tests; diagnosis—made from accurate history, determination of other substances ingested
(usually acetylsalicylic acid or acetaminophen), plasma osmolarity and, if obtainable, methanol level;
treatment—provide fomepizole or ethanol as antidote; give 50 mg of folate q4 to 6h (methanol metabolized to
formaldehyde then to formic acid; folate used to metabolize formic acid to CO2 and H2 O); monitor anion gap,
methanol level, electrolytes, ABG, and blood pressure (BP), and check vision
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| Hemodialysis: ethanol, methanol, isopropanol, and ethylene glycol metabolized by liver but amenable to hemodialysis;
blood flow rates of 250 to 300 mL/min shorten half-life of toxins; performed in patient with metabolic acidosis
and osmolar gap; measure plasma osmolarity before dialyzing patient to determine whether methanol already
completely metabolized
|
| Ethanol vs fomepizole: 10% ethanol in 5% dextrose in water (D5W) solution—can measure loading and maintenance
dose and ensure blood level of methanol >1000 mg/L; may be in short supply (add 50 mL ethanol to 5% ethanol
in D5W); inexpensive ($110 per 1 L; typical course ≈$300); fomepizole—not associated with vasodilation,
hypotension, hypoglycemia, inebriation, pancreatitis, gastritis, or phlebitis (these side effects rarely associated with
12-24 hr ethanol infusion); does not require monitoring; give 1 dose and wait 12 hr, unless patient on hemodialysis;
expensive (typical course costs ≈$3000)
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| Calculations: osmolarity—should be 280 to 290 mOsm/L in healthy patient; serum sodium (Na) x 2 + BUN/2.8 +
glucose/18 + ethanol (mg/L)/46; calculated osmolarity minus measured osmolarity gives osmolar gap (mOsm/L)
|
| Indications for dialysis: serum methanol level >500 mg/L; significant metabolic acidosis without other cause and
anion gap (non-anion gap acidosis not associated with ingestion of methanol or ethylene glycol) and significant osmolar
gap without other cause (osmolar gap ≥25 mOsm/L associated with significant overdose); also consider methanol
level, presence of serious end-organ damage (eg, visual problems), inability to give alcohol dehydrogenase
inhibitor (eg, ethanol or fomepizole), or if patient in hemodynamic decline despite support
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| Differential diagnosis: measure lactate to rule out lactic ketoacidosis in profoundly sick patient in intensive care
unit (ICU); uncharged amino acids released by toxic liver or dying cells not compensated for by Na ions can cause
osmolar gap of 20 to 30 mOsm/L in ICU patient; measure ketones in blood or urine to rule out alcoholic ketoacidosis
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| Toxin half-lives: methanol clears in 24 to 48 hr; ethanol or fomepizole slows half-life of methanol down to 2 to 3
days; hemodialysis speeds half-life up to 2 to 3 hr
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| Isopropanol: not as toxic as other alcohols; metabolized by alcohol dehydrogenase to acetone and excreted in
urine; patients rarely develop acidosis; half-life 10 hr (acetone half-life 15 hr); overdose can produce CNS depression;
supportive care indicated; hemodialysis rarely indicated
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| Ethylene glycol: color and sweet taste interest children; toxic in small amounts; metabolizes to glycolic acid, then
to glyoxylic acid (both contribute to metabolic acidosis), and finally to oxalate; oxalate crystals can precipitate
throughout body and damage tissues and organs
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| RECEIVING THE HAZMAT PATIENT —Kenneth A. Williams, MD, Clinical Associate Professor of Emergency
Medicine, Brown University Medical School, Providence, RI
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| Hazardous materials (HAZMAT) incidents: information sources—HAZMAT defined by Office of Hazardous
Materials Safety within Department of Transportation (http:// hazmat.dot.gov); United States produces many hazardous
chemicals (500,000 shipments per day); Chemical Transportation Emergency Center
(Chemtrec;www.chemtrec.org), sponsored by Chemical Manufacturers Association, provides information and assistance
to emergency responders to HAZMAT incidents; Office of Hazardous Materials (OHM) registry—
provides incident surveillance; includes thousands of toxic releases and exposures and hundreds to thousands of injuries
and deaths; most HAZMAT incidents happen in industrial facilities, but 20% occur during transport; problematic
issues—40% of emergency responders did not wear personal protective equipment (PPE); if responders do
not wear PPE, accident victims likely not decontaminated at scene, and arrive in ED contaminated; facilities required
to report HAZMAT incidents, but information may not get to hospital personnel; transport vehicles have
different colored placards that indicate type of hazardous materials (may not be recognized by emergency responders);
registry data on 49,000 single-substance events recorded during study period; fair number of incidents involve
hospital personnel; 2562 events involving transport of hazardous materials resulted in injury to 32 hospital employees;
resources—National Library of Medicine’s Wireless Information System for Emergency Responders (Wiser;
http://wiser.nlm.nih.gov/) can be searched by symptoms or anatomic location (narrows search from thousands to
small list of toxic materials; patient can provide more details about hazardous substance involved in incident to narrow
list further)
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| Recognizing HAZMAT incidents: avoid learning about HAZMAT incident from symptoms of ED staff; Emergency
Response Guide (ERG) lists hazards of unknown substances and states self-contained breathing apparatus
and fire gear insufficient protection against hazardous materials; recommends evacuating area one half mile around
HAZMAT incident; patient should be decontaminated before entering hospital in order to avoid evacuation of ED
and hospital personnel; recognizing terrorist attack—ideally, want knowledge of spill and location of incident; terrorists
do not provide this type of information; terrorist may use secondary device designed to injure emergency responders
and may target hospital; look for geographic clustering of sick people with same symptoms (eg, several
people get sick at same event); look for characteristic signs and symptoms not seen on daily basis; geographic clustering
of dead animals in public areas followed by cluster of sick people can indicate use of weapon of mass destruction
(WMD; eg, domestic cats tend to die within 24 hr of exposure to anthrax); different symptoms may occur
in domestic and farm animals; consider forging relationships with local veterinary community
|
| Rhode Island disaster initiative: arose out of looking at 30 yr of National Transportation Safety Board (NTSB)
reports of disasters in United States and seeing reports in medical literature describing same lessons learned during
different disasters
|
 | Phase 1 study: designed and built high-fidelity disaster simulation center for study; found 44% of experienced emergency
medical technicians (EMTs), emergency physicians and nurses opened door to hazardous scene; 34% of
participants entered room and touched contaminated victim; triage behavior—state of Rhode Island uses Simple
Triage and Rapid Treatment (START) algorithm in rescue training; START allows 30 sec to triage each victim;
study found 71% of EMT personnel took >90 sec to triage victims, did not use START protocol, and
approached viable victims first before victim in cardiac arrest; skills or subset of skills used every day may be
sufficient to assess scene and patients; PPE—looked at whether patient assessments can be performed while
wearing level-C PPE; some brands or types of equipment work better and may be easier to use; study found some
powered air purifying respirators (PAPR) quieter, some masks had better visibility, some suits cooler, and personnel
able to intubate, inject, palpate pulses, and communicate well while in PPE; conclusions—first responders
likely to rush in to hazardous scene (training and appropriate equipment decreases likelihood of this); some
triage algorithms not useful (may apply to blunt trauma and hemorrhagic shock, but not to burns or chemical
spills)
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| Phase 2 study: used simulated disaster scene involving terrorist bombing of family medicine clinic; bomb contained
Lewisite, blistering agent that produces blisters on skin and lung tissue; first EMT at scene must establish
incident command and triage; other personnel roles include treatment officer, staging officer, and loading officer;
50% of group had 1 or 2 hr of brief training, remainder had only everyday professional skills; ideally, team
suits up, talks about decontamination, talks to victims through door rather than rushing into contaminated scene,
and decontaminates walking wounded; brief training used simple algorithm involving simple instructions (which
drugs to give for which situations, eg, give dimercaprol [BAL] for respiratory trouble and blistering); results
showed training improved entry decisions, helped responders choose appropriate PPE, focused care, and improved
critical action performance, eg, choosing correct antidote, decontaminating victims; training associated
with small delay in care; nontrained teams entered space without PPE, leading to self-contamination, did not decontaminate
patients, and focused critical actions on unsalvageable victims; concluded disaster plan should be
flexible and involve scalable increase in familiar daily activities; provide brief training (including “just in time”
training) and make PPE available in emergency vehicle or in ED
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| Phase 3: using critical care ground transport system as training tool
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| Personal protective equipment: level A—involves self-contained breathing apparatus; probably not useful in
ED; level B—involves breathing air from tube; may be useful; level C—breathe from air cartridge through mask
or hood; level D or daily wear—not sufficient for HAZMAT incidents); general—includes masks for breathing,
suits, gloves, boots, and tape; can find ratings for different brands and types; Superfund Amendments and Reauthorization
Act (SARA) Title 3 and Occupational Safety and Health Administration (OSHA) require use of level-A PPE
if hazardous material unidentified
|
| Standards and policies: responder training—many levels of training; all ED staff should have awareness-level
training; critical care transport—standards and policies for transporting HAZMAT patients come from Commission
on Accreditation of Medical Transport Systems; need to have policy in place to deal with transportation of incident
victims
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| Summary: most non-WMD HAZMAT industrial and transportation; identify materials, don PPE, and decontaminate
victims; some first responders likely to become contaminated; be prepared to decontaminate victims and responders
at hospital; disaster plan must be familiar, brief, simple, and flexible
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Educational Objectives
| The goal of this activity is to educate the listener about the management of toxic alcohol ingestion and emergency
management of hazardous materials (HAZMAT) scenes and victims at scene and in the Emergency department (ED).
After hearing and assimilating this program, the clinician will be better able to:
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| 1. Describe the signs and symptoms of methanol-induced metabolic acidosis.
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| 2. Discuss the indications for hemodialysis in a patient with metabolic acidosis.
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| 3. Decide whether to use fomepizole or ethanol as an antidote in methanol-induced metabolic acidosis.
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| 4. Train first responders and ED personnel in the management of HAZMAT scenes and victims.
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| 5. Formulate a HAZMAT disaster plan and select the appropriate level of personal protective equipment.
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Discussed on this Program
Acetaminophen (several trade names)
Aspirin (acetylsalicylic acid; ASA) (several trade names)
Dimercaprol [BAL in Oil]
Fomepizole (4-methylpyrazole; 4-MP) [Antizol]
Povidone iodine [ACU-dyne, Aerodine, Betadine, Betagen, Biodine Topical 1%, Etodine, Iodex, Iodex-P, Mallisol,
Minidyne, Operand, Polydine, Povidine]
Suggested Reading
Burgess JL et al: Emergency department hazardous materials protocol for contaminated patients. Ann Emerg Med.
34:205, 1999; Burgess JL et al: Hospital preparedness for hazardous materials incidents and treatment of contaminated
patients. West J Med. 167:387, 1997; Ciraulo DL et al: A survey assessment of the level of preparedness for
domestic terrorism and mass casualty incidents among Eastern Association for the Surgery of Trauma members. J
Trauma. 56:1033, 2004; Chong CF: Methanol is a highly toxic alcohol. Resuscitation. 61:368, 2004; Cone DC et
al: Hazardous materials preparedness in the emergency department. Prehosp Emerg Care. 1:85, 1997; Ghilarducci
DP et al: Hazardous materials readiness of United States level 1 trauma centers. J Occup Environ Med. 42:683, 2000;
Hantson P et al: Formate kinetics in methanol poisoning. Hum Exp Toxicol. 24:55, 2005; Lehmann J: Considerations
for selecting personal protective equipment for hazardous materials decontamination. Disaster Manag Response.
Sep:21, 2002; Megarbane B et al: Current recommendations for treatment of severe toxic alcohol poisonings. Intensive
Care Med. 31:189, 2005; Purssell RA et al: The use of the osmole gap as a screening test for the presence of exogenous
substances. Toxicol Rev. 23:189, 2004; Treat KN et al: Hospital preparedness for weapons of mass
destruction incidents: an initial assessment. Ann Emerg Med. 38:562, 2001; Williams K et al: Rhode Island Disaster
Initiative. Med Health R I. 86:207, 2003; Zaman F et al: Isopropyl alcohol intoxication: a diagnostic challenge. Am J
Kidney Dis. 40:E12, 2002.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant financial
relationship with the manufacturer or provider of any commercial product or service discussed. For this issue,
the faculty reported no conflicts.
Drs. Nierenberg and Williams were recorded May 16, 2005, in Lebanon, NH, at Managing Medical Emergencies,
sponsored by the Emergency Department at Dartmouth-Hitchcock Medical Center, and the New Hampshire Chapter
of the American College of Emergency Physicians. The Audio-Digest Foundation thanks the speakers and the sponsors
for their cooperation in the production of this program.
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