Toxicology Flashcards
Management Dig Toxicity
1) NS
2) Digibind if:
- Hemodynamically significant arrhythmia
- K >5, AKI
- Altered LOC
Osmolar Gap Calculation
Serum Osm - [2Na + Gluc + BUN + 1.25*EtOH]
DDX High Anion Gap (>12), Normal Osmolar Gap (<=10)
Methanol ingestion (late) Uremia/AKI DKA (and other ketoacidosis - starvation, ETOH) Propylene glycol Lactic acidosis - A/B Ethylene glycol/EtOH ingestion (late) Salicylates ingestion
Cyanide/CO poisoning
Tylenol infection
DDX High Anion Gap (>12) and High Osmolar Gap (>10)
Methanol Ethylene Glycol Propylene Glycol EtOH (can correct for this in calc OG) ESRD (without IHD)
DDX High Osmolar Gap (>10), Normal Anion Gap (<=12)
Early Methanol/Ethylene Glycol/Propylene Glycol Early EtOH Isopropyl alcohol Hypertriglyceridemia Hyperproteinemia
Manifestations ASA toxicity
Early:
- NV
- Hyperventilation (resp alkalosis)
- Tinnitus
- Fever
Late:
- AGMA
- Arrhythmia
- HTN –> Hypotension
- Non-cardiogenic pulm edema
- Cerebral edema, coma, seizure
- AKI
- Thrombocytopenia
- Elevated INR (factor 2 depletion)
Acid-base abnormality in ASA toxicity
Resp alkalosis + AGMA If see resp acidosis: -CNS depression -Acute lung injury -Mixed overdose: benzos, EtOH
Treatment ASA Toxicity
1) Charcoal/WBI if within 2 hrs (longer if enteric coated or bezoar), NOT if somnolent.
2) Dextrose 1 amp - for neuroglycopenia
3) Sodium Bicarb infusion to alkalinize urine 1-2amps then 250cc/hr (target bld pH 7.4-7.5, urine pH 7.5-7.8)
* Correct hypoK first
4) IHD indications:
- Worsening vitals, hypoxemia, aLOC despite tx
- Severe acidemia pH <=7.20 despite tx
- Vol overload preventing Na bicarb
- ASA lvl >7.2mmol/L w normal renal fcn or >6.5 with AKI
- Hepatic failure with coagulopathy
Indication and C/I to methylene blue
Indications:
- Symptoms or methemoglobinemia >20%
C/I:
- On SSRI/SNRI/MAOi or other serotonergic agent (causes serotonin tox)
- G6PD deficiency
- Pregnancy
Manifestations of TCA Overdose & Ix
-what causes false positive
Arrhythmias: Wide QRS, long QT, Sinus tach, VT, ECG (tall R in aVR, deep S in 1/avL, Type 1 Brugada - RBBB downslope STD V1-V3) Altered LOC, agitation, psychosis Seizures (if QRS>100) Hypotension Anticholinergic toxidrome
Ix: ECG, VBG shows resp acidosis
TCA serum lvls not helpful
Urine false + for TCA w/ QTP, benadryl, cyclobenzaprine
Treatment TCA overdose
1) Charcoal or WBI if within 2 hrs
2) Seizures: Benzos –> propofol (NO dilantin bc cardiac tox)
3) Arrhythmia:
- QRS>100, VT, hypotension: Sodium bicarb (bolus–> maintenance) targetting pH 7.5-7.55, QRS <100
- Refractory VT: MgSO4 –> Lido –> Intralipid –> ECMO
- No increased elimination or antidote
- Avoid flumazenil if co-ingestion bc lowers sz threshold
- NO physostigmine - causes cardiac arrest in TCA tox
Clues to determine which toxic EtOH
1) Ethylene glycol
- CN palsies
- Urine + oxalate crystals –> hematuria, dysuria, flank pain
- HypoCa –> prolonged QT
2) Methanol:
- Blindness, retinal sheen, RAPD, optic disk hyperemia
- Mydriasis
3) Isopropyl
- High OG, Low AG
Treatment Toxic EtOH
Isopropyl –> Supportive
Methanol/Ethylene Glycol:
1) Fomepizole/EtOH if:
- known ingestion and OG >10 (if already low, too late)
- possible ingestion and 2 of: pH <7.3, bicarb <20, OG >10, urine + oxalate crystals
- Serum MeOH >6.2, EG >3.2
2) Na Bicarb, target pH >7.35
3) IHD if:
- High or persistent AGMA
- End organ dmg (AKI, vision, coma, seizure)
- pH<=7.15
- Very high lvl parent alcohol
*no role of decontaminating (NG if w/i 1h)
Serotonin Syndrome Features
HYPERREFLEXIA, MYOCLONUS Fever Diaphoresis Autonomic instability (HTN, tachycardic) ALOC - anxiety, agitated
Onset within24h, offset 24h
Triggers serotonin syndrome
SSRIs, SNRIs, TCA, MAOis Fentanyl, Tramadol Serotonin Ag: Triptans, Ergot VPA, St John's wort Cocaine, MDMA Methylene Blue
NMS Features
FARM
F: Fever
A: Autonomic instability (LABILE BP, dysrhythmia, diaphoresis)
R: Rigidity and HYPOREFLEXIA (NO CLONUS)
M: Mental status change (agitation, catatonia, coma)
Onset days to weeks, offset 2 weeks
Triggers NMS
Anti-psychotics (Typicals >Atypicals)
Anti-emetics (domperidone, metoclopramide, prochlorperazine)
Treatment Serotonin Syndrome
Stop agent
Supportive care
Benzos (target no agitation or hypertonia)
Cryptoheptadine if refractory
Treatment NMS
Stop agent
Supportive care
Benzos
Dantrolene/Bromocriptine as adjuncts
Anticholinergic Toxidrome
Fever Hypertensive Tachycardic Red + Dry Dilated pupils Confused/Agitated Tremor Absent Bowel sounds, urinary/fecal retention
Sympathomimetic Toxidrome
Increased fever, BP, HR, RR Red + sweaty Dilated pupils Altered LOC \++ Bowel sounds
Cholinergic Toxidrome
Sweaty, salivation, lacrimation, urinary/fecal incontinence
Pupils constricted
Bronchorrhea/tachypnea
+/-Low HR/BP
Narcotic Overdose Presentation
Dry Hypothermic Pinpoint pupils Low HR/BP Very low RR Coma/Stupor
Treatment organophosphate toxicity
- Atropine if: miosis, sweating, hypotension, resp distress, bradycardia
- 100% FiO2 +/- ETT **avoid succinylcholine (cleared by AchE), can use Roc at high dose
- IVF for hypotension and brady
- Wash patient thoroughly, wear protection
*atropine S/E: agitation, urinary retention, ileus, hyperthermia, tachy causing MI
Treatment BB/CCB OD
Glucagon
High dose insulin with dextrose
Carbon Monoxide Poisoning: Diagnosis
CarboxyHb >3% in non-smokers
>10-15% in smokers
PaO2 normal bc it reflects dissolved O2
Pulse Ox cannot screen for CO
Carbon Monoxide Poisoning: Treatment
1) High flow O2 by NRB (100%)
2) Remove source of CO
3) Hyperbaric O2 indications:
- COHb >25% (>20% if pregnant, or fetal distress)
- pH <7.1
- Coma
- MI
- Within 6h of exposure
*if CO poisoning after smoke inhalation, must tx for cyanide poisoning
Cyanide Poisoning: Treatment
- 100% O2 via ETT
- Hydroxycobolamine 70 mg/kg (aka Cyanokit)
2nd line. If antidote unavail, use amyl/Na nitrites + Na thiosulfate (S/E hyperNa)
Target methemoglobin concentration 20-30%
Dialysis should NOT be done
Metformin overdose Tx
1) Na Bicarb
2) Supportive Care
3) IHD if:
- Lactate >= 20
- pH <= 7
- Shock requiring vasopressors
- Profoundly depressed LOC
- Liver failure with INR >= 1.5
- Failure of supportive care after 2-4 hrs
ECG prolonged QT causes
- Anti’s: -biotic, -psychotic - emetic - depressants - arrhythmics
- Lytes: Hypo-
- Cocaine
Dig toxicity ECG
- Tachy (VT/VF) or brady (2nd-3rd HB)
- Accelerated junctional tachy
- Do NOT give Ca for HyperK
Pupil changes with toxins
Dilated: anticholinergic, cocaine, MDMA, hallucinogen, methanol, withdrawal from opioid
Normal: hypothermia, barbituates, antipsychotics
Constricted: cholinergic, opioid
S/S Carbon Monoxide vs Cyanide poisoning
CO:
- Cherry red lips/skin
- H/A, ALOC, nausea
Cyanide (smoke inhalation or nitroprusside)
- Smells of bitter almonds
- Cherry red skin
- Equalization of arterial and venous O2 sat
- ALOC
- LACTATE>8
- Metabolic/Lactic acidosis with increased AG –> CV collapse and death
Cyanide poisoning Dx
Cyanide level >2.4 (resp depression/coma), >3 = death
Venous O2 sat from SVC or PA cath >90% (ie decreased utilization) - also in CO or hydrogen sulfide
ECG: nonspecific: blocks, bady, tachy
Lithium overdose S/S
GI: N/V/D
CV: T wave flattening in precordial leads, QT prolong, brady, Brugada unmasked
Heme: Leukocytosis
CNS: dizzy, lightheaded, orthostatic, lethargic, slurred speech, ataxia, tremor, myoclonus
Lithium overdose Tx
NO ROLE FOR BICARB
Whole bowel irrigation if within 6h ingestion, unknown amount, sustained release, symptoms, or increasing levels (no role for charcoal)
IVF
DO NOT force diurese (increases retention)
IHD if:
- Arrhythmias
- Seizures or severe ALOC
- Li lvls >5mmol/ or >4mmol/L with AKI (Cr>176)
Organophosphate poisoning S/S
AchE inhibitor –> excess Ach
CVS: QT prolong, IM, CV collapse
Resp: resp failure (CNS depression), diaphragmatic weakness, secretions, bronchoconstriction
Neuro: lethargy, sz, coma; intermed syndrome (24-96h after exposure: neck flexion, hyporeflex, CN abN, prox muscle weaknes); delayed neuropathy (1-3wks post ingestion painful stocking/glove paresthesia then motor polyneuropathy w/ flaccid weakness of lower extremities)
