Author:
Denise A.Whitfield
David A.Tanen
Description
- Class of sedative-hypnotic agents
- Derivatives of barbituric acid
- Mechanism:
- Enhances activity of -aminobutyric acid (GABA)
- At high levels, directly opens GABA-A associated chloride channel
- Leads to inhibition of vascular smooth muscle tone
- May lead to direct myocardial depression
Etiology
Overdose of barbiturates:
- Intentional or nonintentional
Signs and Symptoms
- CNS:
- Lethargy
- Slurred speech
- Incoordination
- Ataxia
- Coma (can mimic brain death)
- Loss of reflexes
- Cardiovascular:
- Ophthalmologic:
- Miosis (generally associated with deep coma)
- Nystagmus
- Dysconjugate gaze
- Other:
- Respiratory depression
- Hypothermia
- Bullae or “barb blisters”
- Death results from respiratory arrest and cardiovascular collapse
History
- Determine if there was an intentional overdose:
- Pill bottles at the scene
- History of depression or suicidal ideation
- Determine if there was a medication error:
- What other medications was the patient taking?
- Were there any recent changes in dose?
- Estimate how long the patient may have been unresponsive
Physical Exam
- CNS abnormalities:
- Respiratory depression
- Cardiovascular:
- Bradycardia and hypotension
- Ophthalmologic:
- Miosis
- Nystagmus
- Dysconjugate gaze
- Hypothermia
- Bullae or “barb blisters”
Essential Workup
- Fingerstick glucose
- Oxygen saturation monitor
- Monitor BP
ALERT |
Barbiturate poisoning can mimic brain death:- Cannot pronounce a patient brain dead until barbiturate poisoning has been ruled out
|
Diagnostic Tests & Interpretation
Lab
- Electrolytes, BUN/creatinine, glucose:
- Calculate anion gap
- Assess for renal failure
- Urinalysis:
- Creatine phosphokinase for evidence of rhabdomyolysis
- Urine toxicology screen
- Obtain serum phenobarbital level (if suspected)
- Acetaminophen and salicylate levels if suspected suicide attempt
- Thyroid function tests
Diagnostic Procedures/Surgery
- Noncontrast head CT
- Lumbar puncture
Differential Diagnosis
- Sedative-hypnotic poisoning (including -hydroxybutyrate [GHB] and its precursors)
- Carbon monoxide poisoning
- CNS infections
- Space-occupying lesions of the head
- Hypoglycemia
- Uremia
- Electrolyte imbalance (i.e., hypermagnesemia)
- Postictal state following seizure
- Hypothyroidism
- Liver failure
- Psychiatric illness
Prehospital
- Moderate to severe poisonings require paramedic transport
- Intubation is often necessary because of respiratory depression or loss of gag reflex
- IV access and supplemental oxygen:
- IV fluid bolus for hypotension
Initial Stabilization/Therapy
- ABCs:
- Administer supplemental oxygen
- Severe poisonings usually require endotracheal intubation
- 0.9% NS:
- Hypotensive patients require at least 1-2 L IV fluid resuscitation
- Pressor support may be necessary for refractory hypotension
- Activated charcoal effectively binds barbiturates and may decrease systemic absorption
ED Treatment/Procedures
- Administer 1 dose of activated charcoal:
- Utility greatest if given within 1 hr of ingestion
- Ensure patient is awake and alert (or airway protected) prior to administration
- Consider “gut dialysis” with repeated dose activated charcoal (without sorbitol) given q2-4h (as long as bowel sounds are present)
- Rewarm patient if hypothermic (see “Hypothermia”)
- Treat hypotension resistant to IV fluid bolus with vasopressors (norepinephrine, epinephrine)
- Treat hyperkalemia (from muscle breakdown) with calcium, sodium bicarbonate, insulin and glucose, and /or potassium-binding agents
- Repeat phenobarbital level in 2-4 hr to determine whether level is increasing
- Consider hemodialysis if patient has:
- Decreased or no renal function
- Prolonged coma
- Serum phenobarbital level >100 mg/dL
- Refractory hypotension
- There is no role for urinary alkalinization
Medication
First Line
- Activated charcoal: 1 g/kg PO
- Norepinephrine: 2-4 mcg/min IV titrating to desired effect (to max of 10 mcg/min)
Second Line
- Epinephrine: 0.1 mcg/kg/min titrating to desired effect (to max of 1 mcg/kg/min)
Disposition
Admission Criteria
ICU admission for:
- Coma
- Respiratory depression
- Hypotension
- Hypothermia
- Rhabdomyolysis
Discharge Criteria
Asymptomatic after a minimum of 6 hr of observation with 2 consecutive subtoxic phenobarbital levels before discharge
Issues for Referral
- If intentional overdose, will require psychiatric evaluation
- For nonintentional overdose, referral for adjustment in medications
Follow-up Recommendations
For nonintentional overdose, may need referral for adjustment in medications or change of medications to agents with a greater therapeutic window
- GussawL, CarlsonA. Sedative hypnotics. In: Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed.Philadelphia, PA: Elsevier; 2018.
- LeeDC. Sedative-hypnotics. In: HoffmanRS, NelsonLS, Howland MA, et al., eds. Goldfrank's Toxicologic Emergencies. 10th ed.New York: McGraw-Hill; 2015.
- PondSM, OlsonKR, OsterlohJD, et al. Rand omized study of the treatment of phenobarbital overdose with repeated doses of activated charcoal . JAMA. 1984;251:3104-3108.
- RobertsDM, BuckleyNA. Enhanced elimination in acute barbiturate poisoning—a systematic review . Clin Toxicol (Phila). 2011;49:2-12.
See Also (Topic, Algorithm, Electronic Media Element)
ICD9
967.0 Poisoning by barbiturates
ICD10
T42.3X1A Poisoning by barbiturates, accidental (unintentional), init
T42.3X2A Poisoning by barbiturates, intentional self-harm, init
T42.3X4A Poisoning by barbiturates, undetermined, initial encounter
SNOMED
44003006 Poisoning by barbiturate (disorder)
216497003 Accidental poisoning by barbiturates (event)
418108003 Barbiturate poisoning of undetermined intent (disorder)
296036006 Barbiturate overdose (disorder)