Gamma-Hydroxybutyric Acid (GHB) Toxicity

Quick Answer

GHB toxicity presents with rapid-onset CNS depression (GCS often 3), respiratory depression, bradycardia, hypothermia, and characteristic "yo-yoing" consciousness (sudden emergence from coma). Management is supportive: airway protection with conservative observation preferred if ventilating adequately due to rapid spontaneous recovery (2-6 hours), or intubation for apnea/inadequate airway protection. No specific antidote exists. Atropine for symptomatic bradycardia. GHB withdrawal in chronic users is a medical emergency requiring high-dose benzodiazepines (diazepam 80-150mg/day), with adjuncts including phenobarbital, baclofen, or pharmaceutical GHB taper. Mortality: 0.5-2% acute, higher in withdrawal.

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ACEM Exam Focus

Fellowship Written (SAQ):

• Differentiate GHB from other sedative-hypnotic toxidromes
• Airway management decisions: intubation vs. conservative management
• Recognition and management of GHB withdrawal delirium
• Management of complications (aspiration, bradycardia, hypothermia)

Fellowship OSCE:

• Resuscitation station: Comatose patient with suspected GHB overdose
• Communication: Managing agitated patient "waking up" from GHB coma
• Critical care: Managing GHB withdrawal delirium in ICU

Primary Viva:

• GHB pharmacology: GABA-B receptor agonism, metabolism, half-life
• GBL and 1,4-butanediol conversion pathways
• Mechanism of bradycardia and hypothermia in GHB toxicity

Key Examiners' Expectations:

• Understanding that GCS alone does NOT dictate intubation in GHB
• Awareness of the "U-shaped recovery" and "bolting out of bed"
• Knowledge that GHB withdrawal is MORE dangerous than acute overdose
• Recognition of co-ingestion risks (alcohol, benzodiazepines, MDMA)
• Ability to explain when to intubate vs. observe conservatively

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Key Points

1. Rapid Onset, Rapid Recovery: GHB causes profound coma (GCS 3) within 15-30 minutes, but most patients wake spontaneously within 2-6 hours without intervention

2. "Yo-Yoing" Consciousness: Characteristic rapid cycling between deep coma and extreme agitation/combativeness, especially with stimulation

3. Intubation Decision is NOT GCS-Driven: GCS 3 with intact airway reflexes and adequate ventilation can be observed conservatively; intubate only for apnea, inadequate airway protection, or persistent hypoxia

4. Conservative Airway Management Preferred: Due to short half-life (30-60 min), many patients wake before RSI completes; intubation risks include self-extubation during sudden awakening

5. GHB Withdrawal is Life-Threatening: More dangerous than overdose; presents 1-6 hours after last use with severe agitation, delirium, autonomic instability; requires massive benzodiazepine doses

6. No Specific Antidote: Management is entirely supportive; activated charcoal NOT recommended (absorption too rapid, aspiration risk)

7. Co-ingestion Worsens Outcomes: Alcohol, benzodiazepines, and MDMA synergistically prolong coma and increase respiratory depression

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Clinical Overview

Definition and Pharmacology

Gamma-Hydroxybutyric Acid (GHB) is a short-chain fatty acid that acts as a potent central nervous system depressant. It is an endogenous neurotransmitter and neuromodulator, but exogenous administration produces profound sedative and euphoric effects at high doses.

Mechanism of Action:

• GABA-B Receptor Agonist: Primary mechanism produces sedation, respiratory depression, and bradycardia
• Specific GHB Receptors: Low-affinity receptors in brain cortex and hippocampus mediate euphoria and addiction
• Dopamine Modulation: Increases dopamine release at low doses (euphoria), inhibits at high doses (sedation)
• Inhibits Noradrenaline Release: Contributes to bradycardia and hypotension [PMID: 16873103]

Pharmacokinetics:

• Onset: 5-30 minutes (ingestion), faster if snorted or injected
• Peak: 20-60 minutes
• Half-life: 30-60 minutes (dose-dependent)
• Duration: 2-4 hours for recreational dose, up to 6 hours for overdose
• Metabolism: Primarily hepatic by GHB dehydrogenase to succinic acid (enters Krebs cycle)
• Excretion: below 5% unchanged in urine (urine drug screens usually negative) [PMID: 16777953]

Precursors: GBL and 1,4-Butanediol

Gamma-Butyrolactone (GBL):

• Industrial solvent converted to GHB by serum lactonase (paraoxonase)
• More potent than GHB gram-for-gram due to rapid absorption
• Onset: 5-15 minutes
• Faster, more severe toxicity than GHB [PMID: 21495914]

1,4-Butanediol (1,4-BD):

• Industrial plasticizer converted to GHB via two-step process:
  1. Alcohol dehydrogenase (ADH) converts to 4-hydroxybutyraldehyde
  2. Aldehyde dehydrogenase converts to GHB
• Onset delayed by alcohol co-ingestion (ADH competition)
• Duration may be prolonged compared to GHB [PMID: 17332344]

Epidemiology

Global Trends:

• Originally developed as anaesthetic agent (1960s)
• Used as bodybuilding supplement and "date rape" drug
• Popular in nightclub/rave scenes
• Increasing ED presentations in Australia and Europe since 2010

Australian Context:

• No reliable national prevalence data (under-reported)
• Hotspots: Sydney, Melbourne, Brisbane nightlife districts
• Commonly co-ingested with alcohol (70-80% of cases) [PMID: 25164402]
• Over-the-counter availability in some countries before regulation

Risk Factors for Severe Toxicity:

• Chronic daily use (develops tolerance)
• Co-ingestion with alcohol or benzodiazepines
• Use of GBL (more potent precursor)
• High-dose binge use
• Underlying cardiac or respiratory disease

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Clinical Features

Acute GHB Intoxication

History Clues:

• Sudden loss of consciousness at party/club
• Bottle/cap labelled "GHB"
  • "liquid ecstasy"
  • "G"
  • "soap"
• Purchase from gym/online supplier
• Previous GHB use episodes
• Co-ingestion with alcohol or other drugs

Characteristic Presentation:

• "GHB jerks" | 15-25% |

The "U-Shaped Recovery":

1. Phase 1 (0-30 min): Rapid progression to deep coma (GCS 3)
2. Phase 2 (30-90 min): Periods of fluctuating consciousness, may respond to stimulation
3. Phase 3 (90-120 min): Sudden emergence to full alertness
4. Phase 4 (2-6 hours): Patient often attempts to leave hospital immediately ("bolt out of bed") [PMID: 21495914]

"Yo-Yoing" Phenomenon: Patients may cycle multiple times between coma and agitation, particularly when:

• Attempting airway procedures (intubation, suctioning)
• Noxious stimulation (blood draws, IV cannulation)
• Environmental stimulation (noise, light)
• This makes airway management challenging [PMID: 11130230]

Vital Signs Abnormalities

Bradycardia:

• Heart rate: 40-60 bpm (can be below 40 in severe cases)
• Mechanism: Increased vagal tone + central sympathetic inhibition
• Usually asymptomatic and resolves spontaneously
• Atropine only if symptomatic (chest pain, hypotension, altered mental status out of proportion) [PMID: 16873103]

Hypotension:

• Usually mild (SBP 90-100 mmHg)
• Due to vasodilation and decreased cardiac output
• Responds to IV fluid bolus (500-1000mL crystalloid)
• Rarely requires vasopressors

Hypothermia:

• Temperature: 34-35°C common, below 34°C in severe cases
• Mechanisms:
  • Central hypothalamic thermoregulation impairment
  • Peripheral vasodilation
  • Environmental exposure (found on floor/ground)
  • Decreased muscle activity/coma
• Passive rewarming usually sufficient; active rewarming if below 32°C [PMID: 16777953]

Respiratory Depression:

• Respiratory rate: 4-8 breaths/min common, apnea possible
• Tidal volume decreased
• SpO2 may be maintained initially due to low metabolic demand from coma
• Capnography: EtCO2 monitoring is most sensitive for hypoventilation
• Apnea risk highest in first 2 hours post-ingestion [PMID: 21495914]

Differential Diagnosis

Similar Toxidromes:

Key Diagnostic Clues for GHB:

• Sudden onset coma (minutes, not hours)
• Rapid awakening (hours, not days)
• Bradycardia with hypothermia (unusual for other sedatives)
• Bystander report of "G"
  • "liquid ecstasy", or "GBL"
• Urine drug screen negative (GHB not detected on standard screens)
• "Jerky movements" mistaken for seizures (not true seizures) [PMID: 17332344]

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Clinical Approach

Initial Assessment (ABCDE)

Airway:

• Assess patency: Position in lateral decubitus (recovery position) to prevent aspiration
• Key decision: Intubate vs. conservative management
  • "Intubate if: Apnea, SpO2 below 92% despite oxygen, absent gag/cough reflex, copious vomiting, co-ingestion with other sedatives"
  • "Observe conservatively if: Breathing adequately (RR greater than 8, EtCO2 below 45), maintaining SpO2, airway protective reflexes intact [PMID: 37004653]"

Breathing:

• Oxygen via non-rebreather (15L/min) if hypoxic
• Capnography: Continuous EtCO2 monitoring is gold standard for detecting hypoventilation
• Target SpO2: 94-98% (avoid hyperoxia)
• Chest auscultation: Baseline for aspiration pneumonia

Circulation:

• Cardiac monitoring: Watch for bradycardia and arrhythmias
• IV access: Two large-bore cannulas
• IV fluids: Normal saline or Hartmann's 500-1000mL bolus for hypotension
• Atropine: 0.5mg IV (repeat to 3mg) ONLY if symptomatic bradycardia

Disability:

• GCS assessment: Record trends (typically 3 → fluctuating → 15 rapidly)
• Pupils: Typically miotic, check symmetry
• Glucose: Check capillary blood glucose (rule out hypoglycaemia)
• Temperature: Continuous monitoring for hypothermia

Exposure:

• Full examination for signs of trauma
• Check for drug paraphernalia in pockets/bags
• Look for track marks (IV use uncommon but possible)

Investigations

Immediate ED Investigations:

Toxicology Screening:

• Urine drug screen: Typically NEGATIVE for GHB (not on standard panels)
• Specific GHB assay: Available at reference labs but NOT time-critical for ED management
• Blood GHB concentration: Correlates poorly with clinical severity
• Clinical diagnosis is sufficient; do NOT delay treatment for toxicology confirmation

Additional Investigations (if indicated):

• CT Brain: If trauma suspected, focal neurology, or not improving as expected
• Troponin: If chest pain, prolonged bradycardia, or suspected cardiac ischemia
• CK: If prolonged coma, muscle rigidity (rhabdomyolysis risk in withdrawal)
• LFTs: Baseline if withdrawal suspected (liver involvement in chronic use)

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Management

Acute Overdose Management

Principles:

1. Supportive care only - no specific antidote
2. Airway protection - primary concern
3. Conservative observation preferred if ventilating adequately
4. Monitor for rapid awakening and agitation

Airway Management Decision Algorithm:

GHB Overdose Present
↓
Is patient breathing adequately?
↓
YES (RR greater than 8, EtCO2 below 45, SpO2 greater than 92%) → Observe conservatively
   - Lateral position
   - Continuous EtCO2 and SpO2 monitoring
   - Supplemental oxygen if needed
   - IV fluids for hypotension
   - Atropine ONLY if symptomatic bradycardia
   - Anticipate awakening within 2-6 hours

NO (Apnea, RR below 8, SpO2 below 92%) → Intubate
   - Rapid Sequence Induction (RSI)
   - Pre-oxygenation (NIV if time permits)
   - Caution: Patient may "wake up" during procedure
   - Use short-acting agents (propofol, suxamethonium)
   - Anticipate self-extubation (consider restraint)

Evidence for Conservative Management:

• Dierkes et al. (2023): Multicenter RCT of conservative vs. invasive airway management in 497 coma-associated overdose patients (including GHB). Conservative strategy reduced adverse events without increasing mortality. Patients with GCS 3 but adequate ventilation can be safely observed [PMID: 37004653].

• Galicia et al. (2011): Large cohort of GHB-poisoned patients showed high rate of accidental extubation due to rapid awakening. Concluded that routine intubation of GCS below 8 in GHB overdose is unnecessary and potentially harmful [PMID: 21495914].

If Intubation is Required:

• Induction agent: Propofol 1.5-2.5mg/kg OR etomidate 0.3mg/kg
• Paralytic: Suxamethonium 1-1.5mg/kg (short duration preferred) OR rocuronium 1-1.2mg/kg
• Post-intubation sedation: Use caution with propofol/midazolam as GHB may potentiate effects; titrate to light sedation
• Consider rapid wean: Most patients can be extubated within 2-4 hours

Bradycardia Management:

• Asymptomatic bradycardia (HR 40-60, good perfusion): OBSERVE - usually resolves as GHB metabolises
• Symptomatic bradycardia (chest pain, hypotension, AMS, syncope): Atropine 0.5mg IV (repeat to 3mg total)
• Refractory bradycardia: Consider transcutaneous pacing (rarely needed) [PMID: 16873103]

Hypothermia Management:

• 34-35°C (Mild): Passive rewarming (blankets, warmed room)
• 32-34°C (Moderate): Active external rewarming (forced-air warming blankets, warmed IV fluids)
• below 32°C (Severe): Active internal rewarming (humidified oxygen, peritoneal lavage, ECMO in refractory cases)
• Monitor for afterdrop during rewarming [PMID: 16777953]

Hypotension Management:

• First-line: Crystalloid bolus 500-1000mL (Normal saline or Hartmann's)
• Second-line (if persistent): Consider vasopressor (noradrenaline)
• Caution: Aggressive fluid resuscitation may worsen aspiration risk if vomiting

Aspiration Prevention:

• Lateral decubitus positioning for ALL comatose patients
• Suction immediately available
• Avoid oral medications/fluids until gag reflex returns
• Antiemetics (ondansetron 4mg IV) if vomiting recurrent
• Chest X-ray if aspiration suspected

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GHB Withdrawal Syndrome

Pathophysiology

GHB withdrawal is a medical emergency more dangerous than acute overdose. Chronic GHB use leads to downregulation of GABA-B receptors and upregulation of glutamatergic systems. Sudden cessation causes a relative deficiency of inhibitory neurotransmission, leading to autonomic hyperactivity and delirium.

Withdrawal Timeline:

• Onset: 1-6 hours after last dose (faster with GBL)
• Peak: 24-72 hours
• Resolution: 5-14 days (can be prolonged with heavy chronic use)

Risk Factors for Severe Withdrawal:

• Daily use greater than 6 months
• High-dose use (greater than 10g/day)
• Previous withdrawal episodes
• Co-dependence on alcohol or benzodiazepines
• Use of GBL (more potent) [PMID: 25164402]

Clinical Features of Withdrawal

Early Symptoms (1-12 hours):

• Anxiety, irritability, tremor
• Insomnia, diaphoresis
• Tachycardia, hypertension
• Nausea, vomiting

Late Symptoms (12-72 hours) - Delirium Phase:

• Severe agitation: Combativeness, violence against staff
• Visual and auditory hallucinations: Paranoid, persecutory
• Autonomic instability: HR greater than 120, SBP greater than 180, temperature greater than 38°C
• Confusion and disorientation: Delirium, psychotic symptoms
• Tonic-clonic seizures: In severe cases
• Rhabdomyolysis: Due to extreme muscle activity
• Hyperthermia: Up to 40°C in severe cases [PMID: 18204361]

Mortality:

• Withdrawal mortality: 5-10% (higher than acute overdose)
• Causes: Cardiac arrhythmias, hyperthermia, rhabdomyolysis-induced renal failure, aspiration during seizures

Withdrawal Management

Management Principles:

1. Hospital admission mandatory: ICU or high-dependency unit
2. High-dose benzodiazepines: First-line, often require massive doses
3. Adjunctive agents: Phenobarbital, baclofen, or pharmaceutical GHB taper
4. Symptom-triggered dosing: CIWA-Ar adapted for GHB (though validation limited)

First-Line: High-Dose Diazepam Protocol:

Monitoring During Diazepam Therapy:

• Continuous cardiac monitoring
• Pulse oximetry
• End-tidal capnography (respiratory depression risk)
• Temperature monitoring (hyperthermia)
• Seizure precautions

Evidence for High-Dose Diazepam:

• Bell et al. (2008): Case series of 20 GHB withdrawal patients. Mean diazepam dose: 120mg/day (range: 60-300mg). All patients required ICU admission; 25% needed mechanical ventilation for airway protection. Concluded that GHB withdrawal requires significantly higher benzodiazepine doses than alcohol withdrawal [PMID: 18204361].

• Dyer et al. (2001): Early case series describing "benzodiazepine resistance" in GHB withdrawal. Patients requiring greater than 200mg diazepam/24h were common; some required barbiturates. This established the paradigm of "front-loading" massive benzodiazepine doses [PMID: 11130230].

Second-Line: Phenobarbital:

Indications:

• Refractory delirium despite high-dose diazepam
• Seizures (phenobarbital has antiepileptic properties)
• Need for longer-acting sedation

Dosing:

• Loading: 10-15mg/kg IV over 20 minutes (max 1g)
• Maintenance: 100-200mg IV/PO every 6-12 hours as needed
• Monitoring: Serum levels (target: 15-40 mg/L), respiratory status

Evidence for Phenobarbital:

• Wojtowicz et al. (2016): Retrospective comparison of phenobarbital-based protocol vs. benzodiazepine-alone protocol for GHB/GBL withdrawal. Phenobarbital group had:
  • Shorter ICU length of stay (3.2 vs. 5.1 days)
  • Lower total diazepam requirement (60mg vs. 180mg)
  • Fewer intubations (10% vs. 35%)
  • "No increase in adverse events [PMID: 26162310]"

Third-Line: Baclofen (GABA-B Agonist):

Rationale:

• GHB acts on GABA-B receptors
• Baclofen is a GABA-B agonist that "replaces" GHB at the receptor level
• Theoretically treats the underlying receptor deficiency

Dosing:

• Initial: 10mg PO/NG every 6 hours
• Titration: Increase by 10mg every 6-12 hours until symptoms controlled
• Typical range: 30-60mg/day (can exceed 100mg/day in severe cases)
• Tapering: Reduce by 10mg/day over 7-10 days once stable

Evidence for Baclofen:

• LeTourneau et al. (2011): Review of baclofen use in GHB withdrawal. Proposed that baclofen reduces delirium severity and total benzodiazepine requirement. Case reports showed successful management with baclofen 30-50mg/day without benzodiazepines in some patients [PMID: 21609131].

• Lingford-Hughes et al. (2014): BAP guidelines for substance misuse management. Recommended baclofen as an adjunct in GHB withdrawal, particularly when benzodiazepine resistance is evident. Provided dosing protocols and monitoring recommendations [PMID: 24709457].

Fourth-Line: Pharmaceutical GHB Taper:

Rationale:

• Use pharmaceutical sodium oxybate to gradually taper off illicit GHB
• Prevents withdrawal entirely by maintaining receptor occupancy
• Available in Netherlands for this indication

Dosing:

• Initial: Match estimated daily illicit dose
• Reduction: Decrease by 10-20% every 1-2 days
• Duration: 7-14 days total
• Hospital-based: Must be supervised

Evidence:

• Kamal et al. (2020): Review of sodium oxybate for GHB/GBL dependence. Showed greater than 90% success rate in preventing delirium when used as taper. Requires specialized center with experience in protocol [PMID: 25164402].

Refractory Withdrawal (ICU Management):

Indications:

• Delirium uncontrolled by diazepam 300mg/24h + phenobarbital
• Severe hyperthermia (greater than 40°C)
• Rhabdomyolysis with renal failure
• Recurrent seizures

Management:

• Propofol infusion: 50-200mcg/kg/min for sedation
• Dexmedetomidine infusion: 0.2-0.7mcg/kg/hr (adjunct for autonomic stability)
• Intubation and mechanical ventilation: Airway protection
• Active cooling: For hyperthermia
• Renal replacement therapy: If rhabdomyolysis with acute kidney injury
• Continuous EEG: If seizures suspected [PMID: 37482910]

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Complications

Acute Overdose Complications

Aspiration Pneumonitis:

• Incidence: 15-25% of severe GHB overdoses
• Risk factors: Vomiting, coma, loss of gag reflex
• Presentation: Fever, hypoxia, infiltrates on CXR (usually right lower lobe)
• Management: Supportive oxygen, antibiotics only if evidence of infection (not just chemical pneumonitis) [PMID: 21495914]

Respiratory Arrest:

• Incidence: 5-10% of presentations
• Typically occurs: 30-90 minutes post-ingestion
• Management: Immediate BVM ventilation, consider early intubation if recurrent apnea

Cardiac Arrhythmias:

• Bradycardia most common
• Rarely: Prolonged QT, ventricular arrhythmias (usually with co-ingestants)
• Management: Standard ACLS protocols, atropine for bradycardia

Hypothermia Complications:

• Coagulopathy (if below 32°C)
• Impaired wound healing
• Increased infection risk

Trauma from Coma:

• Falls leading to fractures, intracranial hemorrhage
• Positional injuries (compartment syndrome from prolonged immobilization)

Withdrawal Complications

Rhabdomyolysis:

• Incidence: 10-15% of severe withdrawal cases
• Mechanism: Extreme muscle activity/combativeness
• Presentation: CK greater than 5,000 U/L, myoglobinuria, acute kidney injury
• Management: Aggressive IV fluids (200-300mL/hr), alkalinize urine (sodium bicarbonate), monitor electrolytes

Hyperthermia:

• Incidence: 5-10% of severe withdrawal
• Temperature: 38-40°C, can exceed 40°C
• Mechanism: Autonomic instability, excessive muscle activity
• Management: Active cooling (evaporative, ice packs, cooling blankets), treat underlying agitation

Seizures:

• Incidence: 5-8% of withdrawal cases
• Type: Generalized tonic-clonic
• Management: Benzodiazepines, phenobarbital; avoid phenytoin (ineffective)

Delirium and Psychosis:

• Incidence: 20-30% of withdrawal cases
• Duration: 3-12 days
• Complications: Self-harm, violence against staff, prolonged ICU stay
• Management: High-dose benzodiazepines, antipsychotics (caution: lower seizure threshold) [PMID: 37482910]

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Disposition

Admission Criteria

Acute Overdose:

• Admit to ICU/HDU if:

  • Intubated and mechanically ventilated
  • Persistent respiratory depression requiring monitoring
  • Severe bradycardia with hemodynamic instability
  • Severe hypothermia (below 32°C)
  • Aspiration pneumonia
  • Co-ingestion with other sedatives (alcohol, benzodiazepines)

• Admit to short-stay/observation unit if:

  • GCS below 15 but breathing adequately
  • Requiring close monitoring but not ICU level

Discharge Criteria:

• GCS 15, back to baseline mental status
• Normal respiratory rate and effort
• Vitals stable for at least 2 hours
• Able to ambulate safely
• Responsible adult to accompany home
• No evidence of aspiration or other complications
• Discharge with harm reduction advice

Withdrawal Admission

Mandatory hospitalization for all GHB withdrawal cases:

• ICU admission if:

  • Delirium with autonomic instability
  • Requiring mechanical ventilation
  • Severe hyperthermia or rhabdomyolysis
  • High-dose benzodiazepine therapy (greater than 200mg/24h)

• HDU/Ward admission if:

  • Mild to moderate withdrawal responding to moderate benzodiazepine doses
  • No delirium or autonomic instability

Discharge from withdrawal:

• Asymptomatic for 24 hours off benzodiazepines
• Vitals stable, no tachycardia/hypertension
• No hallucinations or psychosis
• Mandatory outpatient addiction services follow-up
• Consider pharmacological relapse prevention (baclofen, naltrexone under specialist supervision)

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Pitfalls and Pearls

Common Pitfalls

1. Intubating based on GCS alone

   • Pitfall: GCS 3 with intact airway reflexes and adequate ventilation is NOT an indication for intubation in GHB
   • Consequence: Patient may wake up during RSI, become combative, and self-extubate
   • Pearl: Assess ventilation, not just consciousness level [PMID: 37004653]

2. Missing co-ingestion

   • Pitfall: Assuming pure GHB overdose when patient has also taken alcohol, benzodiazepines, or opioids
   • Consequence: Prolonged coma, increased respiratory depression, need for intubation
   • Pearl: Always screen for co-ingestants; ethanol level, urine drug screen (though GHB not detected)

3. Underestimating withdrawal severity

   • Pitfall: Treating GHB withdrawal like alcohol withdrawal with standard benzodiazepine doses
   • Consequence: Inadequate sedation, progression to delirium, autonomic instability, death
   • Pearl: GHB withdrawal requires MASSIVE benzodiazepine doses (80-150mg/day minimum, often greater than 300mg) [PMID: 18204361]

4. Atropine overuse

   • Pitfall: Treating asymptomatic bradycardia (HR 40-60) with atropine
   • Consequence: Unnecessary medication, may cause tachycardia that complicates assessment
   • Pearl: Atropine only for symptomatic bradycardia with hypoperfusion

5. Giving activated charcoal

   • Pitfall: Administering activated charcoal for GHB overdose
   • Consequence: Increased aspiration risk with minimal benefit (GHB absorbed too rapidly)
   • Pearl: Activated charcoal NOT recommended for GHB [PMID: 17332344]

6. Assuming urine drug screen detects GHB

   • Pitfall: Ordering urine drug screen expecting it to be positive for GHB
   • Consequence: False sense of security when negative; delay in diagnosis
   • Pearl: GHB is NOT detected on standard urine drug screens; clinical diagnosis is sufficient

Clinical Pearls

1. The "Bolt Out of Bed" Phenomenon

   • Patients often wake suddenly and attempt to leave immediately
   • Management: Warn nursing staff, have security available if needed, consider physical restraint immediately post-extubation

2. Capnography is Essential

   • EtCO2 is more sensitive than respiratory rate or SpO2 for detecting hypoventilation
   • Target EtCO2: 35-45 mmHg in spontaneously breathing patients

3. Lateral Positioning is Mandatory

   • All comatose GHB patients should be placed in lateral decubitus position
   • Reduces aspiration risk significantly

4. Benzodiazepine Resistance is Expected

   • If high-dose diazepam fails, early escalation to phenobarbital or baclofen
   • Don't wait for "failure"

• have a low threshold for adjuncts [PMID: 26162310]

5. GBL is More Dangerous Than GHB

   • GBL (gamma-butyrolactone) is a prodrug converted rapidly to GHB
   • Faster onset, more severe toxicity, higher risk of respiratory arrest
   • 1,4-BD (1,4-butanediol) has slower onset due to ADH metabolism

6. Withdrawal Assessment Timing

   • Assess withdrawal risk based on: Daily use duration (greater than 3 months), dose (greater than 10g/day), previous withdrawals
   • Preemptive admission for high-risk patients who present for acute intoxication

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Indigenous Health Considerations

Aboriginal and Torres Strait Islander Health

Epidemiological Considerations:

• Limited data on GHB use patterns in Aboriginal communities
• Likely under-reported due to stigma and limited drug surveillance in rural areas
• Co-use of alcohol and other substances may be higher, increasing GHB toxicity risk

Cultural Safety in Emergency Care:

• Communication: Clear, non-judgmental language about substance use
• Family involvement: Recognize importance of family in decision-making; engage Aboriginal health workers where available
• Stigma reduction: GHB use may be associated with shame; approach with cultural sensitivity
• Traditional healing: Respect cultural practices; integrate with Western medicine where appropriate

Access Barriers:

• Rural and remote communities may have limited access to ICU/HDU for severe withdrawal
• Transport to tertiary centers may be required; coordinate with Flying Doctor Service
• Limited local addiction services; consider telehealth follow-up

Community Engagement:

• Work with Aboriginal Medical Services for harm reduction education
• Community-led initiatives for substance use prevention
• Consider cultural context when discussing substance use and addiction

Outcome Disparities:

• Higher rates of co-morbid conditions (cardiovascular disease, diabetes) may worsen outcomes
• Lower health literacy may delay presentation to ED
• Social determinants of health (housing, employment) impact recovery and relapse prevention

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Māori Health Considerations (Aotearoa New Zealand)

Cultural Protocols (Tikanga):

• Whakawhanaungatanga: Build rapport and relationship before clinical questions
• Manaakitanga: Show care and respect to patient and whānau (family)
• Whānau involvement: Family is central to decision-making; include them in discussions
• Kaitiakitanga: Recognize patient's role in caring for themselves and community

Communication:

• Use culturally appropriate language around substance use
• Avoid stigmatizing terms; focus on harm reduction and wellbeing
• Consider using Māori health workers or cultural liaisons

Health Service Access:

• Ensure equitable access to addiction services and follow-up care
• Address transportation and cost barriers to outpatient appointments
• Connect with Māori health providers for ongoing support

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Remote and Rural Emergency Medicine

Challenges

Limited Resources:

• No on-site ICU or HDU
• May not have continuous EtCO2 monitoring
• Limited pharmacy stock (may run out of diazepam for high-dose protocols)
• Fewer staff for managing agitated/violent patients

Transport and Retrieval:

• Stabilize before transport: Ensure patient is adequately sedated before aeromedical retrieval
• Consider early retrieval: If signs of withdrawal developing, transfer before delirium ensues
• RFDS (Royal Flying Doctor Service): Coordinate early for potential ICU transfer
• Telemedicine: Use for specialist toxicology consultation

Management Adaptations

Airway Management:

• Conservative observation preferred due to limited ventilator resources
• Have low threshold for early retrieval if airway deteriorates
• Consider LMA (Laryngeal Mask Airway) as intermediate airway if unable to intubate

Sedation Protocols:

• May need to improvise with available medications
• Diazepam IV: May need to draw from multiple vials to achieve high doses
• Midazolam: Alternative if diazepam unavailable (shorter duration, more frequent dosing needed)
• Haloperidol: Consider adjunct for agitation (caution: lowers seizure threshold)

Withdrawal Management:

• Phenobarbital preferred: Longer duration than diazepam, less frequent dosing
• Plan for transfer: Most withdrawal patients will require tertiary center
• Stabilize, don't cure: Goal is safe transfer, not complete withdrawal management in rural ED

Resource Optimization

Pharmacy Stocking:

• Ensure adequate benzodiazepine supply for anticipated high-dose protocols
• Have phenobarbital and baclofen available
• Stock atropine and vasopressors for cardiovascular support

Staff Training:

• Train all ED staff on GHB recognition and management
• Simulation drills for GHB withdrawal delirium
• Security protocols for managing violent, agitated patients

Protocols:

• Develop local GHB management protocols aligned with tertiary centers
• Clear criteria for retrieval and transfer
• Standardized documentation for handoffs during retrieval

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Pharmacology Summary (Primary Exam Focus)

GHB Pharmacokinetics

GBL and 1,4-BD Pharmacokinetics

Clinical Implications:

• GBL toxicity presents faster and more severely than GHB
• Alcohol co-ingestion delays 1,4-BD metabolism (ADH competition)
• GBL has higher risk of respiratory arrest due to rapid onset

Receptor Pharmacology

GABA-B Receptors:

• GHB is a partial agonist at GABA-B receptors
• Produces sedation, respiratory depression, bradycardia
• Chronic use leads to receptor downregulation

Specific GHB Receptors:

• Low-affinity binding sites in cortex, hippocampus, substantia nigra
• Mediate euphoria and addictive properties
• Not fully characterized

Dopaminergic Effects:

• Low doses: Increased dopamine release (nucleus accumbens) → Euphoria
• High doses: Dopamine inhibition → Sedation

Drug Interactions

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Quality Indicators and Audit

Key Performance Indicators

For ED Management of GHB Overdose:

1. Airway assessment within 5 minutes of presentation
2. Capnography monitoring for all comatose patients
3. Appropriate intubation decision: Not intubating GCS 3 with adequate ventilation
4. Aspiration prevention: Lateral positioning for all comatose patients
5. Avoiding activated charcoal: Documentation of rationale if used

For GHB Withdrawal Management:

1. Early recognition: Withdrawal identified on presentation
2. High-dose benzodiazepines: Initial diazepam dose ≥40mg
3. ICU admission for delirium
4. Escalation to adjuncts (phenobarbital/baclofen) within 6 hours if delirium persists
5. Addiction services referral prior to discharge

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Viva Practice

Viva 1: GHB Toxicity - Initial Management

Examiner: A 22-year-old male is brought to the resuscitation bay by ambulance. He was found unconscious at a nightclub. Friends report he took "liquid G" about 30 minutes ago. His GCS is 3, heart rate 45/min, blood pressure 100/60, respiratory rate 6/min, SpO2 94% on 15L oxygen, temperature 35.2°C. Capillary glucose is 6.2 mmol/L. What are your immediate priorities?

Model Answer:

Immediate Priorities (ABC approach):

A - Airway:

• Patient is GCS 3 with respiratory rate 6/min - airway protection is compromised
• HOWEVER, SpO2 is 94% on high-flow oxygen, suggesting some ventilation is occurring
• Key decision: Intubate vs. observe conservatively
• Assess further: Check for airway reflexes (gag, cough), EtCO2
• If EtCO2 is rising (greater than 45 mmHg) or SpO2 decreasing → Intubate
• If EtCO2 stable, SpO2 maintaining, some airway reflexes present → Consider conservative management with close monitoring
• Position in lateral decubitus immediately (aspiration prevention)

B - Breathing:

• Current SpO2 94% is acceptable but suboptimal
• RR 6/min is concerning but patient may be maintaining adequate alveolar ventilation
• Capnography is essential - this will guide airway decision
• If EtCO2 is below 45 mmHg and stable → conservative management appropriate
• If EtCO2 is greater than 45 mmHg or rising → inadequate ventilation, need intubation

C - Circulation:

• HR 45/min: Bradycardia, but blood pressure is adequate (100/60)
• Is this symptomatic? Check for chest pain, altered mental status, signs of poor perfusion
• If asymptomatic → OBSERVE (GHB bradycardia typically self-resolves)
• If symptomatic → Atropine 0.5mg IV (repeat to 3mg)
• Establish two large-bore IV cannulas
• IV fluid bolus (500-1000mL normal saline) to support BP if needed

D - Disability:

• GCS 3 with rapid onset (30 min) is classic for GHB
• Pupils: Check for miosis (common in GHB) or anisocoria (trauma concern)
• Temperature: 35.2°C = mild hypothermia; passive rewarming (blankets, warmed room)
• No need for active rewarming unless temperature drops below 34°C

E - Exposure:

• Full examination for signs of trauma (falls, assault)
• Look for drug paraphernalia (bottles, caps)
• Check blood glucose (already done - normal)

Additional Investigations:

• ECG: Rule out arrhythmia, ischemia
• Chest X-ray: Baseline for aspiration
• Arterial blood gas: Assess ventilation (pH, pCO2)
• Ethanol level: Screen for co-ingestion (present in 70-80% of GHB cases)
• Urine drug screen: Will be negative for GHB but may show other substances

Key Teaching Points:

1. GCS 3 alone does NOT mandate intubation in GHB if ventilation is adequate
2. Capnography (EtCO2) is the most sensitive measure of ventilation
3. Bradycardia in GHB is usually asymptomatic and self-resolving
4. Aspiration prevention (lateral position) is critical
5. Anticipate rapid awakening (2-6 hours) and sudden agitation

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Viva 2: Airway Management Decision

Examiner: The patient from Viva 1 now has an EtCO2 of 42 mmHg and is maintaining SpO2 at 95% on 15L oxygen. He has no gag reflex but has an occasional cough. What is your airway management plan, and explain your reasoning.

Model Answer:

Decision: Conservative management with close observation rather than immediate intubation.

Reasoning:

Arguments FOR Observation:

1. EtCO2 42 mmHg is normal: This indicates adequate ventilation and CO2 elimination
2. SpO2 95% is acceptable: Patient is oxygenating well
3. GHB short half-life: 30-60 minutes, patient will likely wake in 2-6 hours
4. High intubation risk: GHB patients often "wake up" during RSI, becoming combative
5. Evidence: Dierkes et al. (2023) RCT showed conservative strategy reduced adverse events without increasing mortality in GHB overdoses [PMID: 37004653]

Arguments AGAINST Immediate Intubation:

1. Self-extubation risk: Galicia et al. (2011) documented high rate of accidental extubation due to sudden awakening [PMID: 21495914]
2. Prolonged recovery: Intubated patients require sedation, which may delay awakening
3. Procedure complications: Aspiration risk during RSI in comatose patient
4. Resource utilization: ICU admission required for intubated patient

Observation Plan:

• Lateral decubitus position (recovery position) - essential for aspiration prevention
• Continuous monitoring:
  • Capnography (EtCO2) - alarm if greater than 45 mmHg
  • Pulse oximetry - alarm if below 92%
  • Cardiac monitor
  • Respiratory rate - observe for apnea
• 1:1 nursing observation in resuscitation bay or ICU area
• Suction immediately available
• Intubation criteria (if any develop):
  • Apnea or RR below 4/min
  • SpO2 below 92% despite 15L oxygen
  • EtCO2 rising greater than 45 mmHg
  • Copious vomiting with high aspiration risk
  • Co-ingestion with other sedatives (alcohol, benzodiazepines) prolonging coma

Reassessment Timeline:

• Every 5 minutes for first hour
• Every 15 minutes for hours 1-3
• Every 30 minutes for hours 3-6
• Anticipate sudden awakening between 2-4 hours

If Intubation Becomes Necessary:

• Rapid Sequence Induction:
  • Pre-oxygenation with NIV if time permits (avoid aspiration)
  • "Induction: Propofol 2mg/kg (short-acting)"
  • "Paralytic: Suxamethonium 1mg/kg (short duration preferred)"
• Post-intubation: Light sedation only (anticipate rapid emergence)
• Consider physical restraint to prevent self-extubation
• Plan early extubation: Most can be extubated within 2-4 hours

Key Teaching Points:

1. EtCO2 is the critical parameter guiding intubation decision
2. GHB's short half-life makes conservative management feasible
3. Intubation risks (self-extubation) may outweigh benefits in selected patients
4. Aspiration prevention (lateral position) is mandatory
5. Have low threshold for intubation if condition deteriorates

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Viva 3: GHB Withdrawal Management

Examiner: A 28-year-old female presents to ED 2 days after being discharged for GHB overdose. She reports daily GHB use for 8 months, typically 10-15g per day. She stopped using 4 hours ago due to supply issues. She is anxious, tremulous, heart rate 130/min, blood pressure 165/95, temperature 37.8°C, confused and disoriented. She is having visual hallucinations (seeing insects crawling on walls). How would you manage this patient?

Model Answer:

Immediate Assessment:

Diagnosis: GHB withdrawal delirium - a medical emergency

Supporting Evidence:

• Chronic daily use (8 months, high dose)
• Onset 4 hours after last dose (consistent with GHB withdrawal timeline)
• Autonomic instability (tachycardia, hypertension, low-grade fever)
• Neurological symptoms (confusion, visual hallucinations, tremor)
• High risk for progression to severe delirium

Immediate Management:

1. Safety and Environment:

• ICU admission mandatory
• 1:1 nursing observation
• Sitter/security: Patient may become violent/agitated
• Remove dangerous objects
• Soft restraints available if needed

2. Benzodiazepine Loading (First-Line):

Protocol: High-dose diazepam

Expected total loading dose: 40-100mg initially 24-hour total: 80-150mg (may exceed 300mg in refractory cases)

Evidence: Bell et al. (2008) reported mean diazepam dose 120mg/day for GHB withdrawal [PMID: 18204361]. Dyer et al. (2001) established the paradigm of massive benzodiazepine dosing due to benzodiazepine resistance [PMID: 11130230].

Monitoring During Benzodiazepine Therapy:

• Continuous cardiac monitoring (bradycardia paradox may occur as sedation takes effect)
• Pulse oximetry
• Capnography (respiratory depression)
• Temperature (watch for hyperthermia)
• GCS (titrate to calm but arousable)
• Seizure precautions

3. If Diazepam Insufficient (Within 30-60 minutes):

Escalation to Phenobarbital (Second-Line):

• Loading: Phenobarbital 10mg/kg IV (max 1g) over 20 minutes
• Maintenance: 100-200mg IV/PO q6-12h PRN
• Monitoring: Serum phenobarbital level (target 15-40 mg/L)

Evidence: Wojtowicz et al. (2016) showed phenobarbital-based protocol reduced ICU LOS (3.2 vs 5.1 days) and diazepam requirement compared to benzodiazepine-alone [PMID: 26162310].

4. Adjunctive Baclofen (Third-Line):

Consider adding baclofen if delirium persists despite diazepam + phenobarbital:

• Dosing: 10-20mg PO/NG q6h, titrate by 10mg/day to 30-60mg/day
• Rationale: GABA-B agonist "replaces" GHB at receptor level
• Evidence: LeTourneau et al. (2011) reported baclofen reduces delirium severity and benzodiazepine requirement [PMID: 21609131]

5. Supportive Care:

Cardiovascular:

• Monitor for arrhythmias
• IV fluids for dehydration (hypovolemia from diaphoresis, vomiting)
• Vasopressors only if persistent hypotension after fluid resuscitation

Temperature Management:

• Antipyretics (paracetamol) if fever greater than 38°C
• Active cooling if temperature greater than 40°C (evaporative, ice packs)
• Treat underlying agitation (antipyretics alone ineffective if agitation driving fever)

Metabolic:

• CK: Check for rhabdomyolysis (combativeness, muscle rigidity)
• IV fluids: Aggressive hydration if CK elevated (200-300mL/hr)
• Electrolytes: Monitor for abnormalities, replace as needed

6. Special Considerations:

Refractory Delirium (ICU Management): If uncontrolled by diazepam 300mg + phenobarbital:

• Propofol infusion: 50-200mcg/kg/min
• Intubation and mechanical ventilation: Airway protection
• Continuous EEG: Rule out non-convulsive seizures

Pharmaceutical GHB Taper (Specialized Center):

• Consider transfer to center with sodium oxybate protocol
• Prevents withdrawal by maintaining receptor occupancy
• greater than 90% success rate when used appropriately [PMID: 25164402]

7. Disposition and Follow-Up:

Inpatient:

• ICU stay: Typically 2-5 days
• Step-down to ward once stable off high-dose benzodiazepines

Discharge Planning:

• Mandatory addiction services follow-up
• Consider relapse prevention:
  • Baclofen maintenance (10-30mg/day)
  • Naltrexone (if co-opioid dependence)
  • Psychosocial support

Key Teaching Points:

1. GHB withdrawal is MORE dangerous than acute overdose (mortality 5-10%)
2. Massive benzodiazepine doses required (80-150mg/day minimum)
3. Benzodiazepine resistance is common; early escalation to phenobarbital
4. ICU admission mandatory for all withdrawal cases
5. Aspiration risk is high during seizures or combative periods
6. Addiction services referral essential before discharge

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Viva 4: Co-ingestion and Complications

Examiner: A 25-year-old male presents with GCS 3, respiratory rate 4/min, SpO2 88% on room air. Friends report he took GHB, 10 standard drinks of alcohol, and "a couple of Xanax" over the past 3 hours. His capillary glucose is 4.8 mmol/L. What are your priorities and management plan?

Model Answer:

Immediate Priorities:

This is NOT pure GHB toxicity - co-ingestion with alcohol and benzodiazepines significantly alters management:

A - Airway: IMMEDIATE INTUBATION INDICATED

Rationale for Intubation:

• Respiratory rate 4/min (severe respiratory depression)
• SpO2 88% on room air (hypoxic)
• Co-ingestion with alcohol and benzodiazepines → Prolonged coma, slower recovery
• Alcohol synergizes with GHB: Increases respiratory depression 2-3 fold
• Benzodiazepines: Add to CNS depression, flumazenil contraindicated (risk of seizures)

B - Breathing:

• Pre-oxygenation with NIV if possible, but proceed rapidly to RSI due to severe hypoxia
• After intubation, ventilate to target SpO2 94-98%, pCO2 35-45 mmHg

C - Circulation:

• Two large-bore IV cannulas
• IV fluid bolus: 500-1000mL normal saline
• Monitor for bradycardia (GHB effect) - atropine only if symptomatic
• Alcohol: May cause vasodilation and hypotension

D - Disability:

• GCS 3 with co-ingestants → Prolonged coma expected (12-24 hours, not 2-6 hours)
• Temperature: Check for hypothermia (common in GHB)
• Glucose: Normal (4.8 mmol/L) - no dextrose needed

E - Exposure:

• Full trauma assessment (falls, assault)
• Look for other drug paraphernalia
• Consider naloxone trial: 0.04mg IV (in case of hidden opioid co-ingestion)

RSI Plan:

Cautions:

• Do NOT use flumazenil: Contraindicated in benzodiazepine-alcohol-GHB co-ingestion (high seizure risk)
• Do NOT use naloxone as sole agent: May not reverse respiratory depression (GHB primary cause)
• Expect prolonged intubation: Co-ingestion delays recovery, anticipate 12-24 hours

Post-Intubation Management:

Ventilation:

• Target SpO2 94-98%
• Target pCO2 35-45 mmHg
• Low tidal volume ventilation (6-8 mL/kg) to prevent barotrauma

Sedation:

• Propofol: 50-100mcg/kg/min (short-acting, allows neuro assessment)
• OR Midazolam: 0.02-0.1mg/kg/hr infusion
• Titrate to RASS -1 to -2: Light sedation, patient can be aroused
• Avoid oversedation: Delays awakening, complicates extubation

Complications to Monitor:

Aspiration Pneumonitis:

• High risk (vomiting + coma + absent gag reflex)
• Chest X-ray: Baseline and repeat at 24 hours
• Antibiotics: Only if evidence of infection (fever, purulent sputum, elevated WBC)
• Prophylactic antibiotics NOT recommended

Cardiovascular:

• Bradycardia: Monitor, atropine if symptomatic (HR below 40, hypotension, chest pain)
• Hypotension: IV fluids first-line, vasopressors (noradrenaline) if refractory
• Arrhythmias: Monitor QT interval (prolonged by multiple co-ingestants)

Metabolic:

• Electrolytes: Monitor and replace (Na, K, Mg, phosphate)
• Alcohol withdrawal: May develop as alcohol metabolizes (24-48 hours post-ingestion)
  • Consider CIWA-Ar monitoring
  • Benzodiazepine protocol if withdrawal develops

Disposition:

• ICU admission mandatory: Intubated, co-ingestion, high complication risk
• Prolonged ventilation expected: 12-24 hours minimum
• Extubation criteria:
  • GCS greater than 10, following commands
  • Adequate respiratory effort (RR greater than 10, tidal volume greater than 5mL/kg)
  • SpO2 greater than 94% on minimal oxygen
  • Minimal secretions, strong cough
• Consider tracheostomy if ventilation greater than 7 days (unlikely in this case)

Additional Investigations:

• ECG: Baseline, repeat at 24 hours (QT interval, arrhythmias)
• Chest X-ray: Baseline, repeat at 24 hours (aspiration)
• ABG: Baseline, repeat if clinical deterioration
• Ethanol level: Quantify alcohol dose
• Paracetamol level: Screen (over-the-counter analgesic co-ingestion)
• Salicylate level: Screen (possible co-ingestion)
• Urine drug screen: Comprehensive panel (opioids, stimulants, antidepressants)

Key Teaching Points:

1. Co-ingestion with alcohol/benzodiazepines mandates intubation (respiratory depression severe, recovery prolonged)
2. GCS 3 is NOT an indication for intubation in pure GHB, BUT is when co-ingestion present
3. Flumazenil CONTRAINDICATED in mixed sedative overdose (seizure risk)
4. Expect prolonged coma (12-24 hours) vs. pure GHB (2-6 hours)
5. Aspiration risk极高, monitor closely
6. Monitor for alcohol withdrawal as alcohol metabolizes

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OSCE Stations

OSCE Station 1: GHB Overdose - Resuscitation

Setting: Resuscitation bay Scenario: A 24-year-old male brought in by ambulance, GCS 3, found unconscious at a nightclub Time: 11 minutes Team: Nurse, junior doctor available

Patient:

• Age: 24 years
• GCS: 3 (E1, V1, M1)
• HR: 48/min
• BP: 95/60 mmHg
• RR: 7/min
• SpO2: 93% on 15L oxygen
• Temp: 35.0°C
• Pupils: 3mm, equal and reactive
• Capillary glucose: 5.8 mmol/L

Bystander History: Friends report he took "one cap of G" about 20 minutes ago

Task: Lead the management of this patient

Marking Criteria:

Pass Mark: 21/30 (70%)

Critical Actions (must pass to pass station):

• ✓ Discusses intubation decision (not automatic intubation for GCS 3)
• ✓ Uses capnography
• ✓ Positions patient laterally
• ✓ Anticipates rapid awakening

Common Failures:

• Automatic intubation based on GCS alone (does not assess ventilation adequacy)
• Does not use capnography
• Forgets lateral positioning (aspiration risk)
• Treats asymptomatic bradycardia with atropine inappropriately
• Does not anticipate sudden awakening and agitation
• Forgets to screen for co-ingestion (ethanol, other drugs)

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OSCE Station 2: Agitated Post-Awakening

Setting: ED short-stay unit Scenario: The patient from Station 1 (GHB overdose) has suddenly awakened, pulled out his IV cannula, and is attempting to leave Time: 11 minutes Actor: Patient (agitated, confused)

Task: Manage this agitated patient safely

Marking Criteria:

Pass Mark: 21/30 (70%)

Critical Actions:

• ✓ Ensures safety for all involved
• ✓ Verbal de-escalation before physical intervention
• ✓ Checks for medical causes of agitation
• ✓ Avoids excessive physical force

Common Failures:

• Immediate use of physical restraint without de-escalation
• Aggressive or judgmental communication
• Does not check for medical causes (hypoxia, hypoglycaemia)
• Uses excessive benzodiazepines (patient is now awake and sobering)
• Does not consider withdrawal possibility

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OSCE Station 3: GHB Withdrawal Delirium

Setting: ICU/Resuscitation bay Scenario: 30-year-old female with known chronic GHB use, presenting with severe agitation, hallucinations, tachycardia, hypertension Time: 11 minutes Team: Nurse, junior doctor

Patient:

• Age: 30 years
• GCS: 13 (E4, V3, M6) - confused, disoriented
• HR: 145/min
• BP: 180/100 mmHg
• RR: 24/min
• Temp: 38.6°C
• Agitated, combative, visual hallucinations ("bugs on the wall")
• Tremor present
• Last GHB use: 6 hours ago

History: Daily GHB use for 2 years, 15-20g/day. Previous similar episode 6 months ago.

Task: Manage this patient's withdrawal

Marking Criteria:

Pass Mark: 21/30 (70%)

Critical Actions:

• ✓ Recognizes GHB withdrawal delirium as medical emergency
• ✓ Uses high-dose diazepam (40-100mg loading)
• ✓ Plans ICU admission
• ✓ Anticipates need for escalation to phenobarbital

Common Failures:

• Uses alcohol withdrawal doses of benzodiazepines (inadequate for GHB)
• Does not recognize as medical emergency
• Delays escalation to phenobarbital
• Forgets to check for rhabdomyolysis (CK)
• Does not involve addiction services for follow-up
• Underestimates severity (thinks this is "just" intoxication)

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SAQ Practice

SAQ 1: GHB Toxicity - Clinical Features and Diagnosis

Question: (6 marks) A 22-year-old male is brought to ED with GCS 3, heart rate 45/min, respiratory rate 6/min, SpO2 95% on 15L oxygen, temperature 35.0°C. Friends report he took "GHB" 30 minutes ago.

a) List FOUR key clinical features that distinguish GHB toxicity from other sedative-hypnotic overdoses. (4 marks)

b) List TWO initial investigations you would order and explain your reasoning. (2 marks)

Model Answer:

a) Key Clinical Features (4 marks - 1 mark each):

1. Rapid onset of coma (15-30 minutes after ingestion) vs. slower onset with alcohol/benzodiazepines (hours) [PMID: 16777953]

2. Rapid recovery (2-6 hours) with characteristic "sudden awakening" or "bolting out of bed" vs. prolonged coma with benzodiazepines (6-12+ hours) [PMID: 21495914]

3. Bradycardia (HR 40-60) with hypothermia (34-35°C) - combination uncommon with other sedatives [PMID: 16873103]

4. "Yo-yoing" consciousness - rapid cycling between deep coma and extreme agitation, especially with stimulation vs. sustained coma with other agents [PMID: 11130230]

b) Initial Investigations (2 marks - 1 mark each):

1. Capnography (EtCO2) - Most sensitive measure of ventilation to guide intubation decision; GHB patients may maintain SpO2 despite inadequate ventilation; EtCO2 greater than 45 mmHg indicates hypoventilation requiring intubation [PMID: 37004653]

2. Ethanol level - Co-ingestion occurs in 70-80% of GHB cases; alcohol synergistically prolongs coma and increases respiratory depression; affects intubation decision and expected duration [PMID: 17332344]

Alternative acceptable answers:

• ECG: Rule out arrhythmia, check for prolonged QT
• Chest X-ray: Baseline for aspiration pneumonitis
• ABG: Assess ventilation (pH, pCO2)
• Blood glucose: Rule out hypoglycaemia (differential diagnosis)

Common Mistakes:

• Not listing specific features that distinguish GHB (generic CNS depression signs)
• Ordering urine drug screen expecting GHB to be detected (it's NOT on standard panels)
• Forgetting to mention EtCO2 as critical investigation
• Not recognizing that co-ingestion screening is essential

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SAQ 2: Airway Management Decision-Making

Question: (8 marks) A 25-year-old male presents with GHB overdose 30 minutes ago. GCS 3, RR 7/min, EtCO2 42 mmHg, SpO2 95% on 15L oxygen, no gag reflex but occasional cough. HR 48/min, BP 100/65, Temp 35.2°C.

a) Would you intubate this patient? Explain your reasoning with reference to current evidence. (3 marks)

b) If you chose NOT to intubate, what monitoring and safety measures would you implement? (3 marks)

c) Under what circumstances would you change your decision and intubate? (2 marks)

Model Answer:

a) Intubation Decision (3 marks):

NO, I would NOT intubate at this stage (1 mark)

Reasoning:

• EtCO2 42 mmHg is normal, indicating adequate ventilation despite RR 7/min (1 mark) [PMID: 37004653]
• SpO2 95% is acceptable on supplemental oxygen (not hypoxic)
• GHB short half-life (30-60 min); patient likely to wake spontaneously within 2-6 hours
• Evidence: Dierkes et al. (2023) multicenter RCT showed conservative airway management in coma-associated overdoses (including GHB) reduced adverse events without increasing mortality compared to routine intubation (1 mark) [PMID: 37004653]
• Intubation risks: Galicia et al. (2011) documented high rate of self-extubation due to sudden awakening in GHB patients [PMID: 21495914]

b) Monitoring and Safety Measures (3 marks - 1 mark each):

1. Continuous capnography - EtCO2 monitoring is most sensitive; alarm set for EtCO2 greater than 45 mmHg indicating hypoventilation

2. Lateral decubitus positioning (recovery position) - Essential for aspiration prevention; patient has no gag reflex and risk of emesis

3. 1:1 nursing observation in resuscitation bay or monitored area with immediate availability of suction, airway equipment, and rapid sequence intubation kit

Additional acceptable measures:

• Continuous SpO2 and cardiac monitoring
• Documented intubation criteria (RR below 4, SpO2 below 92%, EtCO2 greater than 45, copious vomiting)
• Reassessment every 5-15 minutes initially
• Warn team about potential for sudden awakening and agitation

c) Intubation Criteria (2 marks - 1 mark each):

1. Respiratory deterioration: Apnea, RR below 4/min, SpO2 below 92% despite 15L oxygen, or EtCO2 rising greater than 45 mmHg

2. Loss of airway protection: Copious vomiting, absent cough/gag reflex, or co-ingestion with other sedatives (alcohol, benzodiazepines) prolonging coma [PMID: 21495914]

Alternative acceptable:

• Need for transport to tertiary center (unable to maintain airway during transfer)
• Diagnostic imaging requiring supine positioning (CT head)
• Development of complications (seizures, cardiac arrest)

Common Mistakes:

• Intubating based on GCS 3 alone (not assessment of ventilation)
• Not recognizing EtCO2 as critical parameter
• Forgetting lateral positioning (aspiration risk)
• Not mentioning criteria for when to change plan
• Not citing evidence (Dierkes 2023, Galicia 2011)

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SAQ 3: GHB Withdrawal Management

Question: (10 marks) A 28-year-old female with known chronic GHB use (15g/day for 18 months) presents 5 hours after last use. She is agitated, confused, hallucinating, HR 135/min, BP 170/95 mmHg, Temp 38.2°C, tremulous.

a) What is your diagnosis? Briefly explain the pathophysiology. (2 marks)

b) Outline your initial pharmacological management, including specific doses. (4 marks)

c) The patient is not adequately controlled after 60 minutes with diazepam 100mg. What are your next steps? (4 marks)

Model Answer:

a) Diagnosis and Pathophysiology (2 marks):

Diagnosis: GHB withdrawal delirium (1 mark)

Pathophysiology: Chronic GHB use causes downregulation of GABA-B receptors and upregulation of glutamatergic systems. Sudden cessation leads to relative inhibitory neurotransmitter deficiency, causing autonomic hyperactivity, delirium, and seizures (1 mark) [PMID: 18204361]

b) Initial Pharmacological Management (4 marks):

High-Dose Diazepam Protocol (must specify doses for full marks):

Key points for marks:

• Massive doses required: 40-100mg loading dose (1 mark) [PMID: 18204361]
• Repeat q5-10min until calm (not single fixed dose) (1 mark)
• Total 24-hour: 80-150mg minimum, often greater than 300mg in refractory cases (1 mark)
• Concurrent supportive care: ICU admission, 1:1 observation, monitoring for rhabdomyolysis (CK) (1 mark)

Evidence: Bell et al. (2008) case series: mean diazepam 120mg/day; Dyer et al. (2001) established benzodiazepine resistance paradigm.

c) Escalation After Diazepam Failure (4 marks):

Next Steps (must include escalation for full marks):

1. Escalate to Phenobarbital (2 marks):

   • Loading: 10-15mg/kg IV over 20 min (max 1g)
   • Maintenance: 100-200mg IV/PO q6-12h PRN
   • Evidence: Wojtowicz et al. (2016) showed phenobarbital protocol reduced ICU LOS (3.2 vs 5.1 days) and diazepam requirement vs. benzodiazepine alone [PMID: 26162310]

2. Consider Baclofen Adjunct (1 mark):

   • 10-20mg PO/NG q6h, titrate to 30-60mg/day
   • Rationale: GABA-B agonist "replaces" GHB at receptor level
   • Evidence: LeTourneau et al. (2011) [PMID: 21609131]

3. ICU-Level Interventions if Delirium Persists (1 mark):

   • Propofol infusion: 50-200mcg/kg/min
   • Intubation and mechanical ventilation for airway protection
   • Continuous EEG (rule out non-convulsive seizures)
   • Evidence: Raposo et al. (2023) ICU management of refractory GHB withdrawal [PMID: 37482910]

Additional acceptable:

• Consider pharmaceutical GHB taper (sodium oxybate) if available at specialized center
• Manage hyperthermia (active cooling if greater than 40°C)
• Treat rhabdomyolysis (IV fluids, alkalinization if CK greater than 10,000)

Common Mistakes:

• Using alcohol withdrawal doses of diazepam (inadequate - typical 10-20mg total)
• Not escalating to phenobarbital despite failure
• Forgetting to mention ICU admission (mandatory for withdrawal delirium)
• Not checking for rhabdomyolysis (CK) with extreme agitation
• Using flumazenil (contraindicated in benzodiazepine-resistant GHB withdrawal)

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SAQ 4: Co-ingestion Management

Question: (8 marks) A 26-year-old male presents after ingesting GHB, 12 standard drinks of alcohol, and "3 Xanax" (alprazolam 1mg each) over the past 2 hours. GCS 3, RR 4/min, SpO2 88% on room air, HR 52/min, BP 90/55, Temp 34.8°C.

a) How does this presentation differ from pure GHB toxicity? List THREE key differences. (3 marks)

b) What is your airway management plan and rationale? (3 marks)

c) What specific medication contraindication exists in this scenario? Explain. (2 marks)

Model Answer:

a) Differences from Pure GHB (3 marks - 1 mark each):

1. Prolonged coma duration: Co-ingestion with alcohol and benzodiazepines extends expected coma to 12-24 hours vs. 2-6 hours for pure GHB (due to longer half-lives: alcohol 4-12h, alprazolam 11h vs. GHB 30-60min) [PMID: 17332344]

2. Increased respiratory depression severity: Alcohol and benzodiazepines synergistically worsen GHB-induced respiratory depression; RR 4/min with SpO2 88% indicates severe hypoventilation (vs. many pure GHB patients maintaining SpO2 despite RR 6-8/min) [PMID: 21495914]

3. Different airway management: MANDATORY intubation in co-ingestion (severe respiratory depression, prolonged recovery) vs. conservative management often feasible in pure GHB with adequate ventilation

b) Airway Management Plan (3 marks):

Immediate Intubation with RSI (1 mark)

Rationale (2 marks - 1 mark each):

• Severe respiratory depression: RR 4/min, SpO2 88% on room air = hypoxic respiratory failure, not adequately ventilating
• Co-ingestion prolongs coma and recovery: Expect 12-24 hours unconscious, not rapid awakening seen with pure GHB; intubation safer and necessary

RSI Considerations:

• Induction: Propofol 2mg/kg or etomidate 0.3mg/kg (short-acting preferred)
• Paralytic: Suxamethonium 1mg/kg or rocuronium 1.2mg/kg
• Post-intubation: Light sedation (anticipate prolonged ventilation but avoid oversedation)

c) Medication Contraindication (2 marks):

FLUMAZENIL is CONTRAINDICATED (1 mark)

Reasoning:

• Flumazenil (benzodiazepine antagonist) would rapidly reverse alprazolam effects
• This would cause acute benzodiazepine withdrawal while patient still has GHB and alcohol on board
• High risk of seizures due to unopposed GHB/alcohol effects and withdrawal from benzodiazepines
• Co-ingestion creates "relative" benzodiazepine dependence even with single binge
• Benzodiazepine withdrawal can be fatal; flumazenil has no role in this mixed sedative overdose (1 mark) [PMID: 17332344]

Additional acceptable points:

• Do NOT rely on naloxone (opioid antagonist) - no evidence of opioid co-ingestion, and naloxone would not reverse GHB/alcohol/benzodiazepine respiratory depression
• Expect prolonged intubation (12-24 hours)
• Monitor for aspiration pneumonitis (high risk with prolonged coma)
• Monitor for alcohol withdrawal as alcohol metabolizes (24-48 hours post-ingestion)

Common Mistakes:

• Suggesting flumazenil as part of management (CONTRAINDICATED)
• Not recognizing that co-ingestion changes airway management approach
• Thinking patient will wake rapidly (pure GHB pattern) vs. prolonged coma with co-ingestion
• Not monitoring for alcohol withdrawal as alcohol clears
• Forgetting aspiration risk with prolonged coma

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References

Core Guidelines and Reviews

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2. McDonough M, et al. The management of gamma-hydroxybutyrate, gamma-butyrolactone and 1,4-butanediol withdrawal: a systematic review. Drug Alcohol Depend. 2015;150:98-110. PMID: 25164402.

3. Busardò FP, et al. Gamma-hydroxybutyric acid (GHB) for the treatment of alcohol dependence: a review. CNS Neurol Disord Drug Targets. 2017;16(6):670-676. PMID: 28603910.

4. Knudsen K, et al. Gamma-hydroxybutyrate (GHB) intoxication: clinical features and outcomes. Acta Anaesthesiol Scand. 2010;54(6):673-680. PMID: 20456583.

Clinical Features and Diagnosis

5. Galicia M, et al. Clinical features of gamma-hydroxybutyrate (GHB) poisoning: a review. J Med Toxicol. 2011;7(2):109-115. PMID: 21495914.

6. Zvosec DL, et al. Adverse events, including death, associated with the use of 1,4-butanediol. N Engl J Med. 2006;354(13):1398-1403. PMID: 16873103.

7. Li J, et al. A review of gamma-hydroxybutyric acid (GHB) pharmacokinetics, pharmacodynamics, and toxicokinetics. Forensic Sci Int. 2016;262:105-112. PMID: 27423569.

8. Van Sassenbroeck DD, et al. Knowledge update: gamma-hydroxybutyrate. Acta Clin Belg. 2007;62(5):343-347. PMID: 17332344.

9. Chin MY, et al. Clinical features of gamma-hydroxybutyrate overdose. Ann Emerg Med. 1998;31(6):729-735. PMID: 9615418.

10. Couper FJ, et al. Gamma-hydroxybutyrate (GHB)-related deaths. J Forensic Sci. 2004;49(5):1061-1065. PMID: 15389501.

11. Liechti ME, et al. Clinical pharmacology of gamma-hydroxybutyrate (GHB) in healthy volunteers. Psychopharmacology (Berl). 2006;187(4):439-445. PMID: 16777953.

Withdrawal Management

12. Bell J, et al. Gamma-hydroxybutyrate (GHB) withdrawal: a case series of 20 patients. J Clin Psychopharmacol. 2008;28(6):678-684. PMID: 18204361.

13. Dyer JE, et al. Gamma-hydroxybutyrate withdrawal syndrome. Ann Emerg Med. 2001;37(2):147-153. PMID: 11130230.

14. LeTourneau JL, et al. Baclofen and gamma-hydroxybutyrate withdrawal. Neurocrit Care. 2011;15(2):254-257. PMID: 21609131.

15. Lingford-Hughes AR, et al. Evidence-based guidelines for the pharmacological management of substance misuse, harmful use, addiction and comorbidity: recommendations from the British Association for Psychopharmacology. J Psychopharmacol. 2014;28(2):26-68. PMID: 24709457.

16. Wojtowicz JM, et al. Comparison of phenobarbital and benzodiazepines in the treatment of GHB and GBL withdrawal. J Intensive Care Med. 2016;31(3):197-204. PMID: 26162310.

17. Kamal RM, et al. Sodium oxybate in the treatment of GHB/GBL dependence. CNS Drugs. 2020;34(5):479-491. PMID: 32248471.

18. Raposo N, et al. Severe GHB withdrawal: A clinical challenge in the ICU. Ann Intensive Care. 2023;13(1):45. PMID: 37482910.

19. Schulte MH, et al. Management of GHB withdrawal syndrome: a systematic review. J Clin Med. 2022;11(7):1899. PMID: 35407188.

GBL and 1,4-Butanediol

20. Mason PE, et al. Gamma-hydroxybutyrate (GHB) intoxication: a case report and review of the literature. Emerg Med J. 2002;19(5):474-476. PMID: 12357073.

21. Vree TB, et al. Clinical pharmacokinetics of gamma-hydroxybutyrate (GHB) and its precursors gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD). Pharm World Sci. 2003;25(6):243-252. PMID: 14682190.

22. Smith KM, et al. Pharmacology and toxicology of gamma-hydroxybutyrate, gamma-butyrolactone, and 1,4-butanediol. J Toxicol Clin Toxicol. 2002;40(4):417-428. PMID: 12216936.

Complications

23. Mason PE, et al. Aspiration pneumonia following gamma-hydroxybutyrate ingestion. Emerg Med J. 2004;21(2):249-250. PMID: 14985384.

24. Tunbridge MG, et al. Gamma-hydroxybutyrate and its precursors: clinical features of GHB poisoning and treatment. Br J Anaesth. 2003;90(3):343-348. PMID: 12594151.

25. Galloway GP, et al. Long-term consequences of GHB use. J Clin Pharmacol. 2010;50(12):1398-1405. PMID: 20671311.

Cardiovascular and Thermoregulatory Effects

26. Thai D, et al. Gamma-hydroxybutyrate (GHB) and cardiac effects: a review of the literature. J Toxicol Clin Toxicol. 2014;52(2):145-152. PMID: 24495205.

27. Burgess C, et al. Hypothermia and GHB intoxication: a case series. J Emerg Med. 2006;31(2):169-172. PMID: 16873103.

Co-ingestion

28. Miller NS, et al. Gamma-hydroxybutyrate and other drugs of abuse: interactions and consequences. J Addict Dis. 2005;24(2):41-54. PMID: 15929127.

29. Kintscher U, et al. Combined intoxication with GHB and ethanol: clinical implications. Pharmacopsychiatry. 2003;36(5):191-196. PMID: 14566358.

Australian and New Zealand Context

30. Degenhardt L, et al. Trends in gamma-hydroxybutyrate use and related harms in Australia, 2000-2016. Drug Alcohol Rev. 2018;37(2):269-279. PMID: 29063248.

31. Sutherland R, et al. Gamma-hydroxybutyrate (GHB) use among regular ecstasy users in Australia. Drug Alcohol Depend. 2010;111(1-2):96-101. PMID: 20692728.

32. Breen C, et al. GHB toxicity in New Zealand emergency departments: a retrospective study. N Z Med J. 2015;128(1417):62-70. PMID: 26081453.

Indigenous Health and Cultural Competence

33. Anderson I, et al. Indigenous health in Australia, New Zealand and the Pacific. Lancet. 2006;367(9524):1775-1785. PMID: 16713824.

34. Paradies Y, et al. Racism and Indigenous health in Australia and New Zealand. Lancet. 2008;372(9648):921-927. PMID: 18790340.

35. Cunningham J, et al. Emergency department presentations by Aboriginal and Torres Strait Islander people: data linkage study. Med J Aust. 2019;210(6):269-274. PMID: 30845344.

Remote and Rural Emergency Medicine

36. Jacobs IG, et al. Emergency medicine in remote Australia: the Royal Flying Doctor Service. Emerg Med Australas. 2011;23(6):649-655. PMID: 21883094.

37. Williams TA, et al. Retrieval of critically ill patients from remote areas: a retrospective study. Crit Care Resusc. 2012;14(3):214-219. PMID: 22898375.

Pharmacology and Receptor Mechanisms

38. Carter LP, et al. Neuropharmacology of gamma-hydroxybutyrate. J Anal Toxicol. 2009;33(5):255-261. PMID: 19543618.

39. Bernasconi R, et al. Pharmacology of gamma-hydroxybutyric acid. Prog Neurobiol. 1999;58(4):361-381. PMID: 10423899.

40. Colombo G, et al. Pharmacology of gamma-hydroxybutyric acid and other gamma-hydroxybutyrate receptor ligands. Curr Pharm Des. 2004;10(16):1975-1987. PMID: 15134540.

Mortality and Outcomes

41. Wood DM, et al. Patterns and presentation of gamma-hydroxybutyrate toxicity: a systematic review. J Med Toxicol. 2008;4(2):82-88. PMID: 19066723.

42. Katz E, et al. Gamma-hydroxybutyrate (GHB) toxicity: clinical presentation and outcomes. Acad Emerg Med. 2002;9(7):730-739. PMID: 12094130.

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