Supportive measures should supersede all other considerations in the management of the poisoned patient. The ABC's always come first. Subsequently, the focus may switch to confirmation of a toxic ingestion and specific management issues.
The majority of poisoned patients only require supportive therapy alone in order to recover. Supportive measures alone (Scandinavian method) including mechanical ventilation and circulatory support will permit survival of most patients who are alive upon arrival at the hospital.
In general, the use of antidotes or specific measures should be limited to those patients with clear indications.
Immediately after establishing iv access, a"coma cocktail"of dextrose, thiamine, naloxone and oxygen should be given to all patients with altered mental status. Hypoglycemia must always be a consideration in the unconscious or poisoned patient. Thiamine should be given routinely to all alcoholics or malnourished patients with altered mental status. Naloxone should be considered in all with respiratory depression. Flumazenil rarely, if ever, has to be given emergently, and more careful consideration of its use should be made.
It is important to seek history from sources other than the patient who is often an unreliable historian. These sources include family, friends, the prescribing physician, pharmacists, pre-hospital care personnel, police, and pill bottles or drug paraphernalia at the scene
Attempt to establish the time and size of the ingestion and thus the likelihood that a potentially lethal quantity was ingested. Also try to determine if the patient has vomited spontaneously as this will decrease the need for gastric emptying procedures.
The vital signs are the most important clues to the diagnosis of poisoning and should be measured often and accurately.
The physical exam should focus on identifying a"toxidrome"or toxic syndrome. This is a pattern of signs and symptoms that suggests a specific class of poisoning and allows one to narrow the differential diagnosis. This provides a starting point for management and may suggest the laboratory tests that follow. However, it should be kept in mind that there are many exceptions to the toxidromes and that polydrug ingestions can present with a confusing variety of mixed and overlapping syndromes.
The physical exam should also include evaluation for head trauma, focal neurologic findings, needle track marks, chest auscultation for signs of aspiration or non-cardiogenic pulmonary edema, and unusual odors on the patients breath.
Toxicology screening provides direct evidence of ingestion (although false positives and false negatives do occur), but rarely impacts upon initial management. Initial management should never await results of such analysis.
Toxidromes
"A pattern of signs or symptoms that suggests a specific class of poisoning"
Opioids
triad of respiratory depression, pinpoint pupils, decreased LOC
bradycardia, hypotension, hypothermia
needle tracks
Sedative / Hypnotics
- benzodiazepines, alcohol, barbituates
altered mental status, stupor, coma, slurred speech
respiratory depression
variable pupil changes
hypotension
hypothermia
barbiturate blisters
Sympathemimetics / Withdrawal
- Cocaine, amphetamines, PCP, pseudoephedrine
HTN, tachycardia,
Mydriasis
Anxiety, delirium, paranoid delusions
Diaphoresis
Increased temperature
Seizures
Anticholinergics
TCA, antihistamines, antipsychotics, Gravol
Hot as a hare, Red as a beet, Dry as a bone, Blind as a bat, Mad as a hatter
Hyperpyrexia, cutaneous vasodilation, decreased saliva, mydriasis, hallucinations
tachycardia
Urinary retention
Decreased bowel sounds
Seizures, dysrhythmias
Important to recognize because there is life-saving treatment and because failure to recognize immediately places health care workers at risk.
Cholinergics
insecticides,carbamate, organophosphates, nerve gas, physostigmine
Salivation, Lacrimation, Urination, Defecation, Gastric cramping, Emesis SLUDGE
Drowning in secretions, profuse sweating
AMS, seizures, coma
Muscle fasciculations
Miotic pupils
Salicylates
fever
tachypnea
tinnitus, lethargy, altered mental status
respiratory alkalosis
metabolic acidosis, ketosis
vomiting
Serotonin Syndrome
fluoxetine, trazadone, meperidine
irritability, agitation, AMS
hyperreflexia, tremor, myoclonus, trismus
ataxia, incoordination
flushing,diaphoresis
diarrhea
fever
Difficult to distinguish from NMS, MH, cocaine intoxication, thyroid storm
Extrapyramidal
haloperidol, phenothiazines
rigidity, tremor
opisthotonus, trismus
choreoathetosis
hyperreflexia
Hallucinogenic
amphetamines, cannabinoids, cocaine, LSD, PCP
hallucinations, psychosis, panic
fever
mydriasis
Bradycardia
Beta- blockers, calcium-channel blockers, Digoxin
Clonidine
Phenylpropanolamine
Carbamates, organophosphates, physostigmine
TCA's
Antidysrhythmics ( Types 1A AND 1C)
Opioids
Hypoxemia, MI, hyperkalemia, hypothermia, hypothyroidism, ICP
Agitation/ Seizures
Temperature alterations
Toxicology laboratory
Toxicology screening provides direct evidence of ingestion (although false positives and false negatives do occur), but rarely impacts upon initial management. Initial supportive management should never await results of such analysis
The notion that ordering a"tox screen"on every patient with a suspected overdose will result in a definitive answer as to what the ingested agents were, is incorrect.
The toxicology laboratory does not even attempt to screen for a large number of substances including most antihypertensives and cardiac medications, hallucinogens, MAOI's, the newer antidepressants, plants, mushrooms, fentanyl, cyanide, metals, and household products.
If the initial urine screen is done too soon after ingestion, the concentration in the urine may be too low for detection.
Furthermore, the drugs found on the screen may not be responsible for the symptoms seen, especially if the drugs are not quantitated. Cocaine metabolites may be detected for days and marijuana metabolites for weeks post-exposure. In addition, the tox results usually do not come back until several hours after most important treatment decisions are made.
Numerous studies have demonstrated that tox screens rarely change initial management and have questioned whether their high cost is justified for routine use.
The following readily obtainable laboratory tests should also be obtained in specific circumstances:
Arterial Blood Gas with Co-oximetry
CO, MetHgb, CN-
Oxygen saturation gap
Respiratory or metabolic acidosis
Urinalysis
FeCl3 test for salicylates
Ketones ( salicylates, ketoacidosis )
Calcium oxalate crystals ( ethylene glycol )
Woods lamp ( ethylene glycol )
Rule out rhabdomyolysis
Electrolytes, BUN, Cr, CPK
Lactate
Serum ketones
Serum osmolarity
Anion gap metabolic acidosis AG = [Na+] - [Cl-] - [HCO3-] Methanol Uremia Diabetic Ketoacidosiss ( AKA, SKA ) Phenformin, Paraldehyde Iron, INH Lactic acidosis Ethylene Glycol Salicylates
Osmol Gap
Calculated osmolality = 2[Na+] + [BUN] + [glucose] + [ ethanol]
Abdominal X-Ray
Choral hydrate, heavy metals, iron, phenothiazines, enteric coated are all radio-opaque
ECG - important to search for signs of TCA's or other cardiotoxic drugs
Beta-HCG in all women of child-bearing age
Toxicology Screening - Knowledge of the quantitative serum levels of the following drugs may impact on therapy:Acetaminophen
ASA
Digoxin
Theophylline
Phenobarb
Iron
Lithium
Methanol, Ethylene glycol
Antidotes
- As many antidotes have the potential for causing harm, they should not be given as a reflex
|
Antidote |
Toxin used for |
Comments |
|
|
Naloxone |
Opiates |
Less to avoid withdrawal |
|
|
Flumazenil |
Benzodiazepines |
Avoid if TCA's, epilepsy, addiction |
|
|
Bicarbonate |
TCA, ASA |
|
|
|
Calcium |
CCB |
||
|
Glucagon |
Beta-blockers, CCB |
Follow with infusion of same dose/hr |
|
|
Physostigmine |
Anticholinergics |
Avoid in TCA's |
|
|
Atropine |
Organophosphates, Carbamates |
Titrate to drying of pulmonary secretions |
|
|
Protopam |
Organophosphates |
||
|
Ethanol |
Methanol, ethylene glycol |
||
|
Pyridoxine |
INH |
||
|
Digibind |
Digoxin |
||
|
N-acetylcysteine |
Acetaminophen |
||
|
EDTA |
Lead |
||
|
DMSA |
Lead |
||
|
BAL |
Arsenic, mercury,lead |
||
|
D-penicillamine |
Ar,lead,Mercury |
||
|
Cyproheptadine |
Serotonin syndrome |
||
|
Sodium nitrite, sodium thiosulfate |
cyanide |
||
|
Desferoxamine |
iron |
||
|
Methylene blue |
Met-hemogloninemia |
Gastric emptying/ decontaimination
Major change in the approach to GI decontamination in the past 10 years. The older recommendations were that the stomach should be emptied using either Ipecac or gastric lavage on all patients suspected of an oral drug overdose.
Several outcome studies have demonstrated superior (due to fewer complications) or equivalent outcomes in patients managed with Activated Charcoal alone as compared to charcoal plus a gastric emptying procedure.
Activated Charcoal used alone as a measure of GI decontamination, when the agents are well adsorbed to charcoal, is the recommended decontamination procedure of choice.
If there is a role for gastric emptying procedures at all, their use should be highly selective and not routine
Risk/ Benefit ratio of gastric emptying is unfavorable for the majority of poisonings, it should not be used for non-toxic doses or non-toxic substances, or when the toxin is no longer likely to be in the stomach ( already vomited, several hours since ingestion, agent rapidly absorbed from stomach)
Gastric lavage
Risks
Aspiration (Charcoal lung)
Upper airway, esophageal, gastric trauma (perforations)
Pneumothorax
Dysrhythmias
Benefits
33% (13 - 70 %) recovery of ingested toxin
? Improved clinical outcomes if performed within 1 hour
Indications ( selective use )
Toxic substance and toxic amount (not for benign ingestions)
Less than one hour from presentation and symptomatic
Airway protected
Agent which doesn't bind to charcoal (iron, lithium, hydrocarbons, alcohols)
Considerations
How well charcoal will bind to toxin
Likelihood the toxin is still in the stomach (time since ingestion)
Limitations of lavage (large pills)
Contraindications
Nontoxic substance or amount
Vomiting (stomach already emptied)
Greater than 1 hour since ingestion
Toxin readily absorbed
Caustics, sharps, petroleum
Large pills or packets (won't fit up tube)
Loss of gag reflex without ETT
- Problems with lavage
Requires patient cooperation unless comatose
Most pills too large to fit through holes in even a 40Fr lavage tube
May"push"stomach contents distally beyond charcoal
Time consuming
Evidence
1)Kulig ( 1985) - Gastric emptying + charcoal vs charcoal alone
No benefit to Ipecac vs AC alone
No benefit to lavage if done > 1 hour after ingestion
2) Albertson ( 1989) - Ipecac + AC vs AC alone
Fewer complications without Ipecac
No difference in outcomes
3) Merrigan ( 1990) - Observation vs AC vs Gastric empty+AC
No benefit to gastric emptying vs AC alone
Gastric emptying increases aspiration pneumonia
4) Pond ( 1995) - 495 Gastric empty + AC vs 417 Ac only
No benefit including < 1 hour and those with severe toxicity
"Gastric emptying procedures can be omitted from the treatment regimen for adults after acute overdose, including those that present within one hour of overdose and those that manifest severe toxicity."
Activated Charcoal
- The most important agent for GI decontamination
Prevents absorption by binding to the drug. May also increase elimination of drug already absorbed by pulling drug from the bloodstream into the gut by creating a favorable diffusion gradient between blood and gut ("GI dialysis"). It can also prevent reabsorption of drugs that have an enterohepatic circulation.
Limitations of charcoal include:
Need 10:1 ratio for 100% absorption, it is difficult to give 10 times as much charcoal as toxin in some intoxications where many grams of drug may be ingested ( i.e., 60 gm of theophylline requires 600 gm of charcoal)
Does not bind small, charged molecules like iron, lithium, arsenic, lead, cyanide
Does not bind alcohols, hydrocarbons, and pesticides
Does not bind caustics ( strong acids and bases)
Aspiration of charcoal has been associated with aspiration pneumonia, ARDS, bronchiolitis obliterans, and death. It should not be given to stuporous, comatose, or convulsing patients unless the airway is protected by an endotracheal tube and a ng tube is in place to administer the charcoal
Multiple- Dose Activated Charcoal (MDAC) - giving repetitive doses of charcoal without sorbitol every 1 to 2 hours may be beneficial in selected overdoses such as theophylline, phenobarbitol, ASA, digoxin, tegretol, nadolol, and dilantin
Whole Bowel Irrigation
WBI with a polyethylene glycol/ electrolyte solution given at 1 to 2 L/hr is used to push tablets or capsules through the GI system. It causes diarrhea by mass action
Indications include drugs not well absorbed by charcoal ( iron, lithium, heavy metals), sustained release pills, or"body-packing"with illicit drugs
Contraindications include obstruction, perforation, or GI hemorrhage
Complications include vomiting, bloating, and rectal irritation
Hemodialysis
Useful for small, water soluable, poorly protein bound drugs, with small volumes of distribution, that are usually eliminated by the kidney
Indications include intoxications with severe end-organ compromise, renal failure, metabolic acidosis or electrolyte disturbances not easily correctable by medical methods, or pulmonary edema
The five most commonly dialyzed drugs are methanol, ethylene glycol, ASA, lithium, and theophylline
Indications for ICU admission
- TCA overdose with signs of cardiac toxicity ( QRS > 0.10 secs )
- Wide alterations in body temperature
- Need for intubation/ ventilation
- Hemodynamic instability, dysrhythmias
- Decreased level of consciousness
- Need for continuous naloxone infusions
- Progressive metabolic acidosis, electrolyte abnormalities
- Need for emergency dialysis
- Staffing issues including the availability of a sitter for suicidal patients
- Rare or poorly understood poisoning (where clinical course and
- potential complications not well understood)
- Rising drug levels requiring close observation / monitoring (e.g. Lithium / ASA / theophylline). Even if dialysis criteria not yet met.
- Potential for delayed toxicity requiring prolonged monitoring (e.g. SR CCBs or BBs)
- Patient with significant underlying medical conditions which may exacerbate toxicity (heart disease / etc)
References
General
1) Kulig K: Initial management of ingestions of toxic substances.
N Engl J Med 326: 1677-1681,1992
2) Brett AS: Implications of discordance between clinical impressions and toxicology analysis in drug overdose. Arch Intern Med 148:437, 1988
3) Kellerman AL, Fihn SD, LoGerfo JP, et al: Impact of drug screening in suspected overdose. Ann Emerg Med 16:1206,1987.
4)Mahoney JD, Gross PL, Stern TA, et al: Quantitative serum toxic screening in the management of suspected drug overdose. Am J Emerg Med 8:16, 1990
5) Kulling P, Persson H : The role of the intensive care unit in the management of the poisoned patient. Med Toxicol 1:375-386,1986
Gastric Emptying
Kulig K, Barr-Or D, Cantril SV, et al: Management of acutely poisoned patients without gastric emptying. Ann Emerg Med 14:562-567,1985
Merigan KS, Woodward M, Hedges et al: Prospective evaluation of gastric emptying in the self-poisoned patient. Am J Emerg Med 8;479-483,1990
Pond SM, Lewis-Driver DJ, Williams GM, et al: Gastric emptying in the acute overdose: A prospective randomized controlled trial. Med J of Aust 163:345-349,1995
Albertson TE, Derlet RW, Foulke GE, et al: Superiority of activated charcoal alone compared with ipecac and activated charcoal in the treatment of acute toxic ingestions. Ann Emerg Med 18:56-59,1989
Kornberg AE, Dolgin J: Pediatric ingestions: Charcoal alone versus ipecac and charcoal. Ann Emerg Med 20:648-651, 1991.