Emergency & Toxicology

Opioid toxicity: naloxone dosing and observation

Clinical Overview and When to Suspect Opioid Toxicity

— Respiratory depression is the lethal feature; bradypnea/apnea drives hypoxic cardiac arrest

— Miosis may be absent with meperidine, tramadol, propoxyphene, diphenoxylate, or co-ingestion of sympathomimetics/anticholinergics

— Unresponsive patient with shallow respirations, especially with track marks, fentanyl patches, or paraphernalia

— Witnessed "found down" with cyanosis and snoring respirations

— Post-operative patient on PCA with declining mental status

— Chronic pain patient on high MME (morphine milligram equivalents) with new sedation, especially after adding benzodiazepine, gabapentinoid, or alcohol

— Pediatric ingestion of grandparent's medications (methadone, oxycodone) — even one pill can be lethal in a toddler

— Synthetic opioids (fentanyl, carfentanil) now dominate US overdose deaths; heroin-only overdoses are increasingly rare

— Adulteration with xylazine ("tranq") causes prolonged sedation refractory to naloxone with necrotic skin ulcers

— Counterfeit pressed pills (M30s) frequently contain fentanyl

— RR ≤12 + decreased mental status → presume opioid until proven otherwise

— SpO₂ may be preserved on supplemental O₂ even while CO₂ rises — end-tidal CO₂ or ABG is more sensitive for hypoventilation

— Pulmonary edema (noncardiogenic) and rhabdomyolysis are common downstream complications

Board pearl: A patient brought in "found down" with RR 6, pinpoint pupils, and SpO₂ 86% on room air does not need a CT head first — give naloxone empirically. Diagnostic and therapeutic in the same maneuver. Delay to imaging while the patient hypoventilates is a tested error.

Step 3 management: Always check fingerstick glucose and consider co-ingestants (benzodiazepines, ethanol, stimulants) before assuming pure opioid toxicity.

Opioid toxidrome triad: CNS depression + respiratory depression (RR <12, shallow, or apneic) + miosis ("pinpoint pupils")

When to suspect in the ED:

Epidemiology shaping suspicion:

Clinical anchors:

Presentation Patterns and Key History

— Witnessed injection or ingestion, rapid loss of consciousness, cyanosis, agonal breathing

— Bystander naloxone (intranasal 4 mg) often given prior to EMS arrival — ask about pre-hospital doses

— Methadone overdose: delayed peak (4 hours PO) and long half-life (15–60 h) → recurrent sedation hours after apparent recovery

— Fentanyl patches: heat (fever, heating pad, sauna) accelerates absorption; chewed or applied to broken skin = massive bolus

— Extended-release oxycodone/morphine: delayed onset 2–4 h; tablet manipulation defeats abuse-deterrent matrix

— Loperamide abuse: high-dose for euphoria → QT prolongation and torsades, not classic toxidrome

— "Speedball" (opioid + cocaine/meth): mixed pupils, agitation followed by respiratory failure

— Opioid + benzodiazepine: deeper, more prolonged CNS depression; higher mortality

— Xylazine co-use: deep sedation, bradycardia, hypotension persisting after naloxone

— Specific agent, dose, route, time of last use

— Chronic opioid use vs. opioid-naïve (dictates naloxone dosing strategy)

— Prescribed MME and last refill; recent dose escalation or rotation

— Prior overdoses, prior need for intubation, prior naloxone response

— Mental health, suicidal ideation, recent incarceration/release (high-risk window for relapse overdose)

— Pregnancy status, breastfeeding

— State PDMP (Prescription Drug Monitoring Program) review is standard of care

Key distinction: A chronic opioid user given a full 0.4 mg IV naloxone bolus may develop precipitated withdrawal (vomiting, agitation, catecholamine surge, flash pulmonary edema). An opioid-naïve overdose patient generally tolerates higher initial doses safely.

Board pearl: Methadone and extended-release products mandate prolonged observation (≥24 h) regardless of initial naloxone response — recurrence of sedation is the rule, not the exception.

Classic acute overdose:

Insidious presentations:

Polysubstance clues:

Key history to extract (from patient, family, EMS, pill bottles, EHR PDMP):

Physical Exam Findings and Hemodynamic Assessment

— RR <12, often 4–8; periods of apnea between shallow breaths

— SpO₂ low on room air; EtCO₂ elevated (>50 mmHg) is the earliest sign of hypoventilation

— HR: typically bradycardic or normal; tachycardia suggests hypoxia, withdrawal, or sympathomimetic co-ingestion

— BP: usually preserved or mildly low; profound hypotension → consider sepsis, hypovolemia, or co-ingestant

— Temperature: hypothermia from environmental exposure; hyperthermia suggests serotonin syndrome (tramadol, meperidine + SSRI) or stimulant co-use

— GCS depressed, often 3–8

— Miosis (1–2 mm, reactive); absent miosis does not exclude opioid toxicity

— Hyporeflexia, hypotonia

— Focal deficits should prompt CT head — opioids alone produce symmetric depression

— Shallow, slow, sometimes agonal "guppy" breathing

— Crackles → aspiration pneumonitis or noncardiogenic pulmonary edema (especially post-naloxone)

— Cyanosis of lips/fingertips

— Track marks, abscesses, cellulitis at injection sites

— Fentanyl patches — check back, behind ears, between toes, in mouth (kids)

— Xylazine-associated necrotic ulcers (often on extensor surfaces, even in non-injection sites)

— Needle in pocket — safety risk to staff

— Methadone, loperamide, buprenorphine: QT prolongation → obtain ECG

— Endocarditis stigmata (Janeway, Osler, splinters) in IV drug users with fever

Step 3 management: During initial assessment, simultaneously: open airway (jaw thrust), bag-valve-mask with 100% O₂, attach monitor + EtCO₂, establish IV/IO, fingerstick glucose, and prepare naloxone. Oxygenation and ventilation reverse hypoxic injury faster than naloxone does — never wait for naloxone before bagging an apneic patient.

Board pearl: A "found down" patient with unilateral pupil dilation or focal deficit needs CT head — opioids alone don't cause anisocoria.

Vital signs:

Neurologic exam:

Respiratory exam:

Skin/extremities:

Cardiac:

Diagnostic Workup — Initial Labs, Imaging, ECG

— Fingerstick glucose — rule out hypoglycemia mimicking toxidrome

— Pulse oximetry + continuous EtCO₂ capnography (gold standard for monitoring ventilation post-naloxone)

— Cardiac monitor

— CBC, BMP (AKI from rhabdomyolysis or hypoperfusion)

— CK — rhabdomyolysis from prolonged immobility; >5,000 U/L warrants IV fluids and renal monitoring

— LFTs (acetaminophen co-ingestion in combo products like Percocet, Vicodin)

— Acetaminophen and salicylate levels — mandatory in any suspected overdose with altered mental status; missed APAP toxicity is a tested pitfall

— Ethanol level

— Lactate (tissue hypoperfusion)

— VBG/ABG: respiratory acidosis (high PCO₂) is the hallmark; mixed acidosis if prolonged hypoxia

— Pregnancy test (β-hCG) in reproductive-age women

— Troponin if prolonged hypoxia or chest pain

— Limitations heavily tested: standard immunoassay detects morphine/codeine/heroin metabolites but commonly misses fentanyl, methadone, oxycodone, tramadol, buprenorphine unless specific panels are ordered

— A negative UDS does NOT exclude opioid toxicity

— False positives: rifampin, quinolones (opiates); dextromethorphan (PCP)

— QTc — methadone (dose-dependent), loperamide, buprenorphine

— Look for ischemia from hypoxic demand

— CXR — aspiration pneumonitis, noncardiogenic pulmonary edema (bilateral fluffy infiltrates post-naloxone)

— CT head if focal deficits, trauma, or persistent altered mental status despite reversal

Board pearl: Order an acetaminophen level on every undifferentiated overdose — combination opioid-APAP products are ubiquitous, and APAP toxicity is asymptomatic in the first 24 h but lethal without NAC.

Key distinction: A "clean" UDS with classic toxidrome = fentanyl or synthetic until proven otherwise; treat clinically.

Bedside (immediate):

Labs:

Urine drug screen (UDS):

ECG:

Imaging:

Diagnostic Workup — Advanced and Confirmatory Studies

— Send-out GC-MS or LC-MS/MS for fentanyl, carfentanil, U-47700, nitazenes when forensic confirmation needed

— Most clinical decisions are made empirically — confirmatory testing rarely changes acute management

— Serum methadone level if torsades or refractory toxicity (rare; usually clinical)

— Repeat ECG q4–6h while sedated — QTc can prolong as drug redistributes

— Ceiling effect on respiratory depression in adults — pure buprenorphine overdose rarely lethal alone

— Pediatric buprenorphine ingestion is NOT benign — case fatalities reported; admit and observe

— High affinity for μ-receptor → may displace other opioids OR require higher naloxone doses to reverse

— POCUS lung: B-lines in noncardiogenic pulmonary edema

— POCUS cardiac: assess EF if hypotensive (endocarditis screening)

— TTE/TEE if febrile IVDU with murmur — modified Duke criteria for infective endocarditis

— Blood cultures × 2 if febrile

— HIV, HCV, HBV serologies — high baseline prevalence; ED-initiated screening is best practice

— Wound cultures from abscesses

— Abdominal CT (or plain film) to identify packets

— Body packers (intentional concealment, well-wrapped): WBI with PEG, surgical consult if obstruction or rupture

— Body stuffers (panic ingestion of unwrapped drug at arrest): higher leak risk, observe with naloxone infusion ready

Step 3 management: For body packers, do NOT give activated charcoal alone (won't bind through wrapping reliably) and avoid endoscopic retrieval (rupture risk). Whole-bowel irrigation with PEG until packets clear; surgery for rupture or mechanical obstruction.

Board pearl: A traveler from a drug-source country with abdominal pain and CT showing radiopaque foreign bodies in colon = body packer until proven otherwise; ICU admit with naloxone drip on standby.

Targeted toxicology panels:

Methadone-specific:

Buprenorphine considerations:

Imaging adjuncts:

Infectious workup in IVDU:

Body packer/stuffer:

Risk Stratification and First-Line Management Logic

— Open airway (jaw thrust, oral/nasal airway)

— Bag-valve-mask with 100% O₂ at 10–12 breaths/min restores oxygenation immediately

— Most opioid deaths are from hypoxia — fix oxygenation before pharmacology

— RR <12 with hypoxia or hypoventilation → yes

— Awake, protecting airway, normal RR but positive UDS → no (observation only)

— Cardiac arrest from suspected opioid: standard ACLS; naloxone is adjunct, not substitute for CPR

— Single dose adequate response → observe (see chunk 16 for duration)

— Required ≥2 doses or reversed a long-acting agent (methadone, ER oxycodone, fentanyl patch, sustained fentanyl exposure) → start naloxone infusion

— Methadone or any long-acting/extended-release opioid

— Required naloxone infusion

— Required intubation

— Pulmonary edema, aspiration pneumonitis, rhabdomyolysis, AKI

— Co-ingestion of long-acting CNS depressant

— Body packer/stuffer

— Pediatric ingestion of any opioid

— After single naloxone dose and full reversal, observe 2–4 hours

— At end of observation: ambulatory, normal vitals, RR ≥12, SpO₂ ≥95% RA, GCS 15 → consider discharge

Step 3 management: Every patient surviving an opioid overdose should leave with (1) take-home naloxone, (2) harm-reduction counseling, (3) warm handoff to MAT (buprenorphine or methadone program), and (4) follow-up scheduled. Discharging without these is a tested patient-safety failure.

CCS pearl: Order set on arrival should be: O₂, IV access, monitor, glucose, naloxone (titrated), CBC, BMP, APAP/salicylate, EtOH, CK, UDS, ECG, CXR — then re-evaluate q15 min.

ABCs first — naloxone is NOT first:

Decision: who gets naloxone?

Decision: bolus vs. infusion?

Disposition triggers for admission:

"Observe and discharge" pathway (short-acting opioid, e.g., heroin/IR fentanyl):

Pharmacotherapy — Naloxone Dosing in Detail

— IV: 0.04–0.4 mg, titrate q2–3 min, double if no response (0.4 → 0.8 → 2 → 4 → 10 mg)

— If no response after 10 mg cumulative → reconsider diagnosis (sedative-hypnotic, head injury, hypoglycemia, postictal, xylazine, clonidine)

— Start LOW: 0.04 mg IV (dilute 0.4 mg in 10 mL saline, give 1 mL)

— Titrate to respiratory effort, not consciousness

— Minimizes withdrawal-induced vomiting, agitation, catecholamine surge

— Rate = ⅔ of the effective bolus dose per hour

— Example: 2 mg bolus reversed the patient → infusion 1.3 mg/h

— Titrate to RR 12–16 and SpO₂ ≥94%

— Have a re-bolus available at half the original effective dose if breakthrough sedation

— May require higher initial doses (2–4 mg or more)

— Often need infusion due to lipophilicity and tissue redistribution

— Flumazenil empirically (seizure risk if benzo-dependent or TCA co-ingestion)

— Naloxone in cardiac arrest as substitute for CPR

Board pearl: Acute precipitated withdrawal + flash pulmonary edema is the catastrophic complication of over-aggressive naloxone — start low in chronic users.

Key distinction: Naloxone half-life (30–90 min) < heroin (2–4 h) < methadone (15–60 h). Re-sedation is expected — observe accordingly.

Mechanism: Competitive μ-opioid receptor antagonist; short half-life 30–90 min (key — shorter than most opioids it reverses)

Endpoint of therapy: adequate ventilation (RR ≥12, normal SpO₂/EtCO₂), NOT full alertness. Over-reversal precipitates withdrawal and pulmonary edema.

Dosing — opioid-naïve or unknown chronic status:

Dosing — chronic opioid user (suspected dependence):

Intranasal: 4 mg (one nostril) or 8 mg formulations; lay-rescuer standard. Repeat q2–3 min if no response.

IM: 0.4 mg if no IV; slower onset (~5 min)

IO: same as IV dosing if no access

Endotracheal: 2–2.5× IV dose (legacy; rarely used)

Continuous infusion (for long-acting opioids, repeated doses needed):

High-potency synthetics (fentanyl, carfentanil):

Avoid:

Procedures and Adjunctive Management

— BVM with oral/nasal airway is first-line; most patients respond to naloxone before intubation needed

— Intubate if: unable to oxygenate/ventilate despite naloxone, severe aspiration, persistent GCS <8 after reversal attempt, refractory pulmonary edema

— RSI considerations: avoid agents prolonging hypotension; ketamine or etomidate reasonable

— IV preferred when access available (fastest titration)

— IN reasonable pre-hospital and when IV difficult

— IM for bystander kits

— Activated charcoal (1 g/kg PO) only if: recent (<1 h) PO ingestion of long-acting opioid AND airway protected (intubated or fully alert) — rarely indicated in practice

— Whole-bowel irrigation (PEG 1–2 L/h) for body packers/stuffers and large ER ingestions

— Remove fentanyl patches — confirm number applied (check prescription); residual drug remains in subcutaneous depot for 12–24 h after removal → continue observation/infusion

— Noncardiogenic pulmonary edema: supportive — O₂, positive pressure (CPAP/BiPAP) or intubation with PEEP; diuretics generally not helpful (not volume overload)

— Rhabdomyolysis: IV crystalloid to UOP 1–2 mL/kg/h; monitor K⁺, Ca²⁺, phosphate

— Aspiration pneumonitis: supportive; antibiotics only if pneumonia develops (not prophylactic)

— Xylazine co-toxicity: supportive — no specific antidote; α₂ effects (bradycardia, hypotension) outlast naloxone window

— Buprenorphine induction in ED is now standard of care for opioid use disorder

— Start when COWS ≥8 (moderate withdrawal); typical dose 4–8 mg SL, may re-dose to 16–24 mg in 24 h

— Bridge with prescription + warm handoff to outpatient program

Step 3 management: ED-initiated buprenorphine doubles 30-day treatment engagement and reduces overdose mortality. Don't discharge a survivor of opioid overdose without offering MAT — this is a Step 3 patient-safety/quality answer.

CCS pearl: Advance clock in 15-min increments after naloxone — reassess RR, SpO₂, EtCO₂, GCS each time.

Airway management:

Naloxone delivery logistics:

Decontamination:

Adjunctive treatments:

MAT initiation in ED:

Special Populations — Elderly and Organ Impairment

— Higher prevalence of chronic pain → chronic opioid exposure → higher tolerance, but also higher iatrogenic overdose risk

— Reduced renal clearance (morphine-6-glucuronide accumulates → prolonged sedation in CKD)

— Polypharmacy: benzodiazepines, gabapentinoids, sleep aids amplify CNS/respiratory depression — AGS Beers Criteria flags chronic opioid + benzo combination

— Lower starting naloxone dose (0.04 mg) to avoid catecholamine surge in patients with coronary disease — precipitated withdrawal can trigger MI, arrhythmia, or stroke

— Longer observation periods; reduced respiratory reserve

— Morphine: active metabolite M6G renally cleared → accumulates in CKD/AKI → recurrent sedation; avoid in ESRD

— Codeine, hydromorphone, oxycodone: also caution

— Preferred opioids in CKD: fentanyl, methadone, buprenorphine (hepatic metabolism, inactive metabolites)

— Naloxone itself: hepatically metabolized; no renal dose adjustment but expect prolonged effect of the offending opioid

— Most opioids metabolized hepatically → prolonged effect in cirrhosis

— Reduce doses; avoid methadone in severe hepatic impairment (variable kinetics, QT risk)

— Naloxone half-life prolonged in cirrhosis — actually beneficial here

— Catecholamine surge from precipitated withdrawal → demand ischemia, takotsubo, pulmonary edema

— Titrate naloxone very slowly; have nitroglycerin/BiPAP available

— Baseline hypoventilation and CO₂ retention → exquisite sensitivity to opioids

— Lower threshold for admission and capnography monitoring

Board pearl: A dialysis patient on chronic morphine presenting with recurrent somnolence despite naloxone boluses needs a continuous naloxone infusion and switch to fentanyl/methadone/buprenorphine for ongoing pain control.

Key distinction: In elderly chronic opioid users, the goal of naloxone is RR ≥10–12, not full alertness — over-reversal can be lethal.

Elderly:

Renal impairment:

Hepatic impairment:

Heart failure / CAD:

OSA / COPD:

Special Populations — Pregnancy, Pediatrics, Neonates

— Naloxone Category C but always give if mother is hypoxic — maternal hypoxia is the dominant fetal risk

— Maternal withdrawal precipitated by naloxone → uterine contractions, placental abruption, fetal distress, preterm labor → use lowest effective dose, titrate carefully

— Continuous fetal monitoring if ≥23 weeks

— Methadone and buprenorphine are standard of care for OUD in pregnancy (not detoxification — relapse risk is high and dangerous)

— Pregnant survivors should be linked to MAT, prenatal care, and social work

— Onset: heroin/short-acting 24–72 h; methadone/buprenorphine up to 5–7 days

— Signs: high-pitched cry, hypertonia, tremors, poor feeding, sneezing, loose stools, fever, seizures

— Modified Finnegan score or ESC (Eat, Sleep, Console) approach guides therapy

— First-line nonpharm: rooming-in, breastfeeding (if on MAT and HIV-negative), swaddling, low stim

— Pharmacologic: oral morphine or methadone for severe symptoms

— Do NOT give naloxone to a neonate born to an opioid-dependent mother — precipitates seizures

— One pill can kill: methadone, buprenorphine, oxycodone, fentanyl patches/lozenges

— Naloxone IV dose: 0.1 mg/kg up to 2 mg in children <5 yo or <20 kg; ≥5 yo: 2 mg per dose

— IN naloxone 4 mg appropriate in older children

— Admit ALL pediatric opioid ingestions for ≥24 h observation — recurrent sedation common

— Mandatory child protective services consultation for suspected exposure/access concerns

— Counterfeit pill use rising; screen for OUD, offer naloxone kit and MAT (buprenorphine FDA-approved ≥16 yo)

Step 3 management: A pregnant woman with opioid overdose gets naloxone titrated to maternal ventilation, NOT withheld for fetal concerns. Then admit, OB consult, social work, MAT initiation.

Board pearl: Toddler "found sleeping" after grandma's visit + miosis + bradypnea → opioid ingestion; give naloxone, search for source pills, notify CPS.

Pregnancy:

Neonatal abstinence syndrome (NAS) / Neonatal opioid withdrawal syndrome (NOWS):

Pediatric ingestion:

Adolescents:

Complications and Adverse Outcomes

— Anoxic brain injury — the dominant cause of mortality and morbidity; depends on duration of apnea before reversal

— Myocardial ischemia/infarction from prolonged hypoxia

— Renal injury, hepatic injury, ischemic bowel

— Noncardiogenic pulmonary edema (NCPE) — classically post-naloxone in 0.2–4% of reversals; bilateral infiltrates, frothy sputum, normal cardiac function on echo; treat with O₂ and positive-pressure ventilation

— Aspiration pneumonitis → secondary bacterial pneumonia

— ARDS from severe aspiration

— Rhabdomyolysis from prolonged immobilization → AKI, hyperkalemia, compartment syndrome

— Compartment syndrome in dependent limbs (gluteal, forearm) — surgical emergency, easy to miss in obtunded patient

— Methadone/loperamide-induced torsades de pointes

— Catecholamine surge from precipitated withdrawal → demand ischemia, takotsubo cardiomyopathy

— Skin/soft tissue: cellulitis, abscess, necrotizing fasciitis

— Bloodstream: bacteremia, infective endocarditis (right-sided > left; S. aureus most common)

— Bone/joint: osteomyelitis (vertebral, sternoclavicular), septic arthritis

— Epidural abscess (back pain + fever + IVDU → MRI emergently)

— HIV, HCV, HBV transmission

— Vomiting + aspiration

— Severe agitation requiring restraint

— Hypertensive emergency, MI, hemorrhagic stroke

— Seizures (less common, more with mixed overdoses)

— OUD progression, repeated overdoses (high 1-year mortality after first overdose: ~5–10%)

— Death — leading cause of accidental death in US adults <50

Board pearl: Survivor of opioid overdose has ~10× higher 1-year mortality than general population; the ED visit is a critical intervention point — MAT initiation cuts this risk substantially.

Key distinction: NCPE post-naloxone is not volume overload — avoid diuretics; treat with PEEP/CPAP.

Hypoxic complications:

Pulmonary:

Musculoskeletal:

Cardiovascular:

Infectious (IVDU):

Withdrawal complications (from naloxone):

Long-term:

When to Escalate Care — ICU, Consults, Admission

— Intubation for respiratory failure

— Continuous naloxone infusion requirement

— Hemodynamic instability

— Long-acting opioid overdose (methadone, ER products, fentanyl patch) with ongoing symptoms

— Body packer/stuffer with packets still in GI tract

— Severe rhabdomyolysis (CK >20,000), AKI requiring CRRT

— Noncardiogenic pulmonary edema requiring high FiO₂/PEEP

— Post-arrest with anoxic brain injury (targeted temperature management if applicable)

— Co-ingestion of TCA, salicylate, calcium-channel blocker, β-blocker, sulfonylurea

— Methadone overdose with prolonged QTc on cardiac monitoring

— Stable on naloxone infusion, no end-organ damage

— Required >2 boluses, now stable

— Single short-acting opioid reversal but social/medical concerns prevent ED discharge

— Aspiration pneumonia

— Skin/soft tissue infection requiring IV antibiotics

— Medical toxicology / Poison Control (1-800-222-1222) — recommended for any complex or pediatric overdose

— Addiction Medicine / Psychiatry — MAT initiation, OUD diagnosis, dual diagnosis

— Social work / case management — housing, insurance, peer recovery specialist

— Obstetrics if pregnant

— Infectious Disease for endocarditis, epidural abscess

— Cardiothoracic surgery for tricuspid endocarditis with criteria

— General surgery for body packer rupture or compartment syndrome

— Facility lacks ICU, pediatric capability, or specialty consults

— Use transfer time to continue naloxone infusion + airway support

Step 3 management: A patient on a naloxone drip is not floor-appropriate — needs ICU or step-down with continuous cardiopulmonary monitoring and capnography.

CCS pearl: When you write "naloxone infusion 0.4 mg/h," also write "transfer to ICU," "continuous EtCO₂," "Q1h neuro/RR checks," and "addiction medicine consult."

ICU admission criteria:

Step-down / telemetry:

Floor admission:

Consults to obtain:

Transfer criteria:

Key Differentials — Other Sedative/Toxic Causes

— CNS depression + respiratory depression similar to opioids

— Pupils normal or mid-position, not pinpoint

— No response to naloxone

— Benzo reversal: flumazenil only in very select cases (naïve patient, iatrogenic, no TCA co-ingestion) — risks seizures

— Miosis, bradycardia, hypotension, CNS depression — mimics opioid toxidrome

— Partial or no response to naloxone (sometimes transient response at high doses)

— Supportive care; atropine for symptomatic bradycardia

— Xylazine increasingly cuts fentanyl supply → "naloxone-resistant" overdoses

— Profound but brief CNS depression with rapid spontaneous awakening

— No reliable antidote; supportive

— Sedation, miosis (quetiapine, olanzapine), hypotension

— QT prolongation, anticholinergic features

— Mydriasis (not miosis), tachycardia, hyperthermia, dry skin, urinary retention, delirium — opposite of opioid in most features

— Miosis (shared with opioids!) but SLUDGE/DUMBELS, fasciculations, bradycardia, bronchorrhea — easy to distinguish

Key distinction: Miosis + respiratory depression + response to naloxone = opioid. Miosis + respiratory depression + no response to naloxone = consider clonidine, xylazine, pontine stroke, or organophosphate.

Board pearl: A patient with persistent sedation despite adequate naloxone, with miosis and bradycardia, on the East Coast in 2023+ → xylazine adulteration. Supportive care only.

Sedative-hypnotic toxidrome (benzodiazepines, barbiturates, GHB, ethanol):

α₂-agonist toxicity (clonidine, tizanidine, dexmedetomidine, xylazine):

GHB / GBL:

Antipsychotic overdose (especially atypicals):

Anticholinergic toxidrome:

Cholinergic toxidrome (organophosphates):

Key Differentials — Other-Category Mimics

— Altered mental status, diaphoresis, tachycardia (or bradycardia in severe), seizures

— Fingerstick glucose on every altered patient — D50 reversal

— CO₂ narcosis in COPD exacerbation can mimic opioid coma; check ABG and history

— Pontine hemorrhage classically causes pinpoint pupils + coma — naloxone unresponsive

— Focal deficits, neck stiffness, hypertension → CT head urgent

— Witnessed seizure, tongue laceration, incontinence, gradual improvement

— Fever, leukocytosis, meningismus; lactate elevated; LP if no contraindication

— Asterixis, jaundice, elevated ammonia, known cirrhosis

— Elevated BUN/Cr, asterixis, myoclonus

— Headache, nausea, cherry-red skin (rare), elevated carboxyhemoglobin; SpO₂ falsely normal on standard pulse ox — use co-oximetry

— Hypothermia, bradycardia, hyporeflexia, hyponatremia

— Triad of confusion, ataxia, ophthalmoplegia; alcoholic or malnourished — give thiamine

— Hyperthermia, hyperreflexia, clonus, agitation, autonomic instability — not pure sedation

Step 3 management: The classic "coma cocktail" remains useful conceptually: oxygen, dextrose (if hypoglycemic), naloxone (if respiratory depression), thiamine (if alcoholic/malnourished). Flumazenil is no longer routine.

Board pearl: Pinpoint pupils + coma + naloxone non-response + hypertension → think pontine stroke and get emergent CT, not more naloxone.

Hypoglycemia:

Hypoxia / hypercapnia from primary lung disease:

Stroke / intracranial hemorrhage:

Postictal state:

Sepsis / meningitis / encephalitis:

Hepatic encephalopathy:

Uremic encephalopathy:

CO poisoning:

Severe hypothyroidism (myxedema coma):

Wernicke encephalopathy:

Serotonin syndrome (tramadol, meperidine + SSRI/MAOI):

Secondary Prevention and Discharge Planning

— Every patient surviving opioid overdose discharges with intranasal naloxone (typically 4 mg ×2) — standard of care, often standing order

— Train patient and at least one family member/friend on recognition (RR <12, blue lips, unresponsive) and use

— Many states have standing orders allowing pharmacy dispensing without individual prescription

— Buprenorphine (SL film/tablet, monthly injectable Sublocade): X-waiver no longer required (Mainstreaming Addiction Treatment Act); any DEA-registered prescriber can prescribe

— Methadone: only via federally certified opioid treatment programs (OTPs)

— Naltrexone (oral or monthly IM Vivitrol): requires 7–10 days opioid-free; lower efficacy than agonist therapy for retention

— Buprenorphine and methadone reduce all-cause and overdose mortality by ~50% — highest-yield intervention

— Warm handoff to addiction medicine clinic within 72 h

— Peer recovery support specialist in ED when available

— Treat comorbid depression, PTSD, anxiety

— Contingency management has evidence for stimulant co-use

— Don't use alone; use Never Use Alone hotline

— Fentanyl test strips

— Syringe service programs (clean needles, HIV/HCV testing)

— Avoid mixing with benzodiazepines and alcohol

— HIV PrEP if indicated; HAV, HBV vaccines; pneumococcal; tetanus

— HCV treatment with DAAs — curative

— Screen for STIs

Step 3 management: A "right answer" on Step 3 for any opioid overdose disposition almost always includes prescribing naloxone + initiating or referring for buprenorphine + scheduled follow-up. Discharge without these = wrong answer.

Board pearl: ED-initiated buprenorphine + referral retains ~75% of patients in treatment at 30 days vs. ~40% with referral alone.

Take-home naloxone (THN):

MAT (Medications for Opioid Use Disorder):

Behavioral / psychosocial:

Harm reduction:

Vaccinations and screening in IVDU:

Follow-Up, Monitoring, and Observation Duration

— Minimum 2–4 hours post-last naloxone dose with normal RR, SpO₂, and mental status

— "St. Paul's / Hospital Discharge Rule" criteria for safe discharge after heroin reversal: ambulatory, normal vitals, GCS 15, no need for additional naloxone within last hour

— More conservative practice extends to 4–6 hours in fentanyl era due to higher potency and longer tail

— Methadone: ≥24 hours in monitored setting due to 15–60 h half-life

— Fentanyl patch: 24 h after removal; subcutaneous depot continues releasing

— Extended-release oxycodone/morphine: ≥12–24 h

— Buprenorphine pediatric ingestion: ≥24 h

— Continuous pulse oximetry and capnography (EtCO₂) — capnography detects hypoventilation before desaturation

— RR documented q15 min initially, then q1h once stable

— Cardiac monitoring if methadone, loperamide, or repeat ECG indicated

— Serial mental status checks

— Addiction medicine: within 72 h

— Primary care: 1–2 weeks

— If on buprenorphine induction: follow-up at 1, 3, 7 days then weekly to titrate dose

— Mental health: within 1–2 weeks

— Tolerance is reset after even brief abstinence (incarceration, hospitalization, detox) → highest overdose risk window

— Avoid using alone

— Naloxone in hand, friends/family trained

— Substance-free transportation home

Step 3 management: A patient leaving AMA after naloxone reversal still gets naloxone in hand and written instructions — harm reduction is independent of care plan adherence.

Board pearl: Post-incarceration release, post-detox, and post-overdose discharge are the three highest-risk windows for fatal opioid overdose; intensify MAT and naloxone access at these transitions.

ED observation after naloxone for short-acting opioid:

Observation for long-acting/ER opioids:

Monitoring parameters during observation:

Outpatient follow-up cadence:

Counseling at discharge:

Ethical, Legal, and Patient Safety Considerations

— A patient acutely intoxicated or post-naloxone may lack decision-making capacity; assess orientation, understanding of risks, and ability to express a reasoned choice

— Sedated/altered patient leaving AMA may require involuntary hold until capacity restored

— Once sober and demonstrating capacity, patients have the right to refuse admission/MAT

— Most US states have laws shielding bystanders calling 911 for an overdose from minor drug possession charges — counsel patients and families

— Encourage bystanders to call and stay

— Pediatric opioid exposure → Child Protective Services (mandated reporter)

— Suspected elder abuse/neglect → Adult Protective Services

— Some jurisdictions require reporting of suspected drug-facilitated assault

— Pregnancy + opioid use: state laws vary widely; some states mandate reporting, others explicitly do not — know your jurisdiction; punitive approaches deter prenatal care

— Mandatory in most states before prescribing controlled substances; document review

— OUD is a chronic medical disease; using "addict," "abuser," "clean/dirty urine" is stigmatizing and reduces engagement — use "person with OUD," "positive/negative toxicology"

— Document with neutral medical language

— 42 CFR Part 2 provides extra confidentiality protections for SUD treatment records — separate consent required for disclosure beyond standard HIPAA

— Failure to prescribe take-home naloxone, failure to offer MAT, failure to schedule follow-up, and discharging an altered patient prematurely are all preventable safety events

— Use teach-back to confirm patient/family understand naloxone administration

— Counsel patients on impairment risk with opioids/benzos; document counseling

Step 3 management: A toddler brought in obtunded with miosis, reversed with naloxone, and discharged home to grandparents who keep methadone unsecured is a CPS report and counseling on safe medication storage — both are required actions, not optional.

Board pearl: Stigmatizing language ("drug-seeker," "addict") in the chart is both unethical and bad medicine — Step 3 rewards person-first, medical-model framing.

Capacity to refuse care:

Good Samaritan laws:

Mandatory reporting:

PDMP query:

Stigma and bias:

Confidentiality:

Transition of care safety:

Driving:

High-Yield Associations and Rapid-Fire Facts

Board pearl: If a question asks "next best step" after reviving a heroin overdose patient who is now alert, the answer is observe + offer buprenorphine + prescribe naloxone + arrange follow-up, not "discharge home with referral list."

Pinpoint pupils, RR <12, coma = opioid toxidrome

No miosis with opioid OD: meperidine, tramadol, propoxyphene, diphenoxylate, or co-ingestion

Meperidine → seizures (normeperidine accumulation, esp. renal failure); serotonin syndrome with MAOI/SSRI

Tramadol → seizures, serotonin syndrome, partial response to naloxone (mixed mechanism)

Methadone → QT prolongation, torsades, long half-life, delayed peak

Loperamide abuse → QT prolongation, torsades

Buprenorphine → partial agonist, ceiling on respiratory depression in adults but lethal in toddlers

Fentanyl patch → heat accelerates absorption; remove and observe 24 h post-removal

Diphenoxylate-atropine (Lomotil) → biphasic toxicity (anticholinergic then opioid), prolonged observation in kids

Naloxone half-life: 30–90 min

Naloxone infusion rate: ⅔ of effective bolus per hour

Pediatric naloxone: 0.1 mg/kg up to 2 mg

Noncardiogenic pulmonary edema post-naloxone: treat with PEEP, not diuretics

Body packer: well-wrapped, intentional → WBI; Body stuffer: panic ingestion → higher rupture risk

IVDU + fever + new murmur → tricuspid endocarditis, S. aureus; get blood cultures, TTE

IVDU + back pain + fever → spinal epidural abscess; MRI emergently

NAS: methadone/buprenorphine onset up to 5–7 days postpartum

OUD in pregnancy: continue methadone or buprenorphine, don't detox

MAT mortality reduction: ~50% with buprenorphine or methadone

Highest overdose risk windows: post-incarceration, post-detox, post-overdose, recent dose escalation

Acetaminophen level on every undifferentiated overdose — combo products

UDS misses fentanyl, methadone, oxycodone, tramadol, buprenorphine on standard panels

Naloxone in cardiac arrest: adjunct, never substitute for high-quality CPR

Xylazine: bradycardia, deep sedation, necrotic ulcers, naloxone-resistant; supportive only

Flumazenil: avoid empirically — seizure risk

Board Question Stem Patterns

— 28 yo found unresponsive in alley, RR 6, pinpoint pupils, SpO₂ 82%. Best next step?

— Answer: BVM ventilation + naloxone 0.4 mg IV (or 0.04 mg if dependence suspected)

— Pt revived with naloxone 0.4 mg now alert; 2 h later RR 8 again. Next step?

— Answer: re-bolus naloxone, start continuous infusion (⅔ of effective bolus/h), admit to ICU

— Elderly woman on chronic morphine for cancer pain, post-op, RR 8, miotic, SpO₂ 90%

— Answer: titrate 0.04 mg IV naloxone, goal RR ≥10, avoid full reversal/precipitated withdrawal

— Toddler found with grandma's pill bottle, somnolent, pinpoint pupils, RR 10

— Answer: naloxone 0.1 mg/kg, admit ≥24 h, CPS notification, education on safe storage

— Hospice patient with patch develops sedation after heating pad applied

— Answer: remove patch, naloxone with infusion preparation, observe ≥24 h

— Patient revived, now alert, asks to leave. Best next step?

— Answer: offer buprenorphine in ED, prescribe take-home naloxone, schedule 72-h follow-up

— Pt with miosis, RR 6, given 10 mg naloxone — no response

— Answer: reconsider diagnosis — pontine stroke, clonidine, xylazine, sedative-hypnotic, hypoglycemia

— 28 wks pregnant, opioid OD

— Answer: naloxone titrated to maternal ventilation, fetal monitoring, OB consult, continue MAT

— Bilateral infiltrates and hypoxia minutes after naloxone

— Answer: positive pressure ventilation (CPAP/BiPAP or intubation with PEEP), not diuretics

— Red flag for epidural abscess — emergent MRI, blood cultures, neurosurgery consult

Step 3 management: Recurring high-yield answer themes: titrate to ventilation not consciousness, observation duration depends on drug half-life, always offer MAT and naloxone at discharge, escalate to infusion + ICU when re-sedation occurs.

Board pearl: When the patient is "found down" with focal neuro findings unresponsive to naloxone, the answer is CT head — not more naloxone.

Stem 1 — Classic acute heroin overdose:

Stem 2 — Methadone overdose with re-sedation:

Stem 3 — Chronic pain patient on opioids becomes obtunded post-op:

Stem 4 — Pediatric ingestion:

Stem 5 — Fentanyl patch with heat:

Stem 6 — Post-overdose discharge planning:

Stem 7 — Naloxone non-responder:

Stem 8 — Pregnant overdose:

Stem 9 — Naloxone-induced pulmonary edema:

Stem 10 — IVDU with fever + back pain:

One-Line Recap

Opioid toxicity is a respiratory-depression emergency reversed by oxygenation and titrated naloxone — dose low in chronic users, observe long enough to outlast the offending drug's half-life, and never discharge without take-home naloxone and an offer of MAT.

Board pearl: The single most testable principle: titrate naloxone to ventilation, not to alertness — over-reversal precipitates withdrawal, vomiting, pulmonary edema, and catecholamine-driven cardiovascular events. Pair every survival with MAT and naloxone-in-hand, because the next overdose is the one that kills.

Diagnose by the triad of CNS depression + RR <12 + miosis; treat empirically when present rather than waiting for confirmatory testing

Reverse with BVM first, then naloxone — 0.04 mg IV for chronic users titrated to RR ≥10–12; 0.4–2 mg escalating in opioid-naïve; intranasal 4 mg for prehospital/bystander; pediatric 0.1 mg/kg

Re-dose strategy — if reversal required ≥2 boluses or the agent is long-acting (methadone, ER products, fentanyl patch, buprenorphine), start a continuous infusion at ⅔ of the effective bolus per hour and admit to ICU/step-down with capnography

Observe ≥2–4 h for short-acting opioids and ≥24 h for methadone/ER products/patches; expect re-sedation as naloxone (30–90 min half-life) wears off before the opioid does

Discharge bundle is the Step 3 high-yield endpoint: take-home naloxone + ED-initiated buprenorphine (or warm handoff to MAT) + 72-h follow-up + harm-reduction counseling + addressing co-occurring HIV/HCV/mental health — these interventions cut 1-year mortality roughly in half and define quality care for this population