Exam 4 Flashcards
Most commonly involved drugs in adult poisoning
- analgesics
– sedatives/hypnotics/antipsychotics
– antidepressants
Approach to patient with unknown overdose
- contact Poison Control Center
- obtain H&P and PMH, although may not be possible
- assess underlying conditions, chronic illnesses, suicidal or not?
- MATTERS acronym
MATTERS acronym
- Medication/substance ingested
- Amount ingested
- Time of ingestion
- Toxicology of the drug
- Emesis/presence of pill fragments
- Reasons for ingestion
- Signs and symptoms
Rapid first look: toxidrome oriented physical exam
- vital signs – hypo or hypertensive, brady or tachycardic
- alert, responsive to voice, responsive to pain, or unresponsive
– pupil size, position, nystagmus - mucous Membranes
- skin temperature and moisture
– presence/absence of bowel sounds
– motor tone
General toxicology Diagnostics
- 12 lead EKG
– plain film radiographs; not much benefit unless packing or drug is radiopaque, or looking for aspiration - toxicology screens: acetaminophen, salicylates, “drugs of abuse” immunoassay, comprehensive urine drug screen
- CMP, K, calcium, glucose, liver enzymes, kidney function, CBC, lactate, ABG
ICU admission criteria for toxicology
- hemodynamic instability: hypotension, non-sinus rhythm, hypothermia, hypoxia
- signs of end organ damage: GCS < 13, unable to protect airway, confusion requiring monitoring for respiratory depression, renal failure, hypertensive emergency, heart block (other than first-degree), life-threatening electrolyte imbalances, rhabdomyolysis, DIC, seizures
- if none of the above are present, they can go to a general medical floor
Be aware of post admission delayed toxic effects
- Late toxic effects: sustained release drugs or problems with absorption
– acetaminophen peaks 24 hours post ingestion
– oral hypoglycemics, insulin, TCAs - methanol, Ethylene glycol, isopropyl alcohol peaks over six hours post ingestion
- ingested drug packets
Geriatric considerations for poisoning/toxicology
- Polypharmacy can lead to unintentional overdose; but do NOT rule out intentional overdose
- May have atypical presenting symptoms
– decline in GFR and creatinine clearance
Pathophysiology of acetaminophen toxicity
Small amount is metabolized to a highly toxic reactive intermediate called NAPQI. NAPQI is normally detoxified by glutathione, but when you take too much acetaminophen, the liver runs out of glutathione leaving a build up of the toxic byproduct NAPQI
acetaminophen toxicity presentation
- often asymptomatic or have mild G.I. symptoms at initial presentation
- can cause varying degree of liver injury over the next four days
- Time sensitive: people treated within eight hours of ingestion rarely have hepatotoxicity; hepatotoxicity can occur with ingestion of over 10 g in 24 hours
Four phases of acetaminophen poisoning
- phase 1: <24 hours; anorexia, malaise, pallor, n/v, diaphoresis
- phase 2: 24-48 hours; RUQ pain, abnormal LFTs
- phase 3: 48 to 96 hours; encephalopathy, coagulopathy, hypoglycemia, LFT peaks, rare – pancreatitis, ARF, MI
- phase 4: >96 hours; decreased LFTs, liver transplant, death, or recovery
Diagnostics for acetaminophen toxicity
- plasma acetaminophen level: must be 4+ hours after ingestion to be accurate/have utility
- baseline AST, AL T, PT/INR, creatinine, serum lactate
- toxicology screen
- Rumack-Matthew monogram: used to decide whether to treat with n-acetylcysteine (Mucomyst) or not
G.I.decontamination for acetaminophen overdose
- emesis and gastric lavage are not recommended
– activated charcoal can be considered if presenting within two hours of ingestion - give anti-emetics (especially if giving acetylcysteine orally)
Antidote for acetaminophen overdose
- Acetylcysteine
- if given within 8 HOURS of ingestion, serious hepatotoxicity and death are uncommon (do not delay giving waiting for the 4 hour level and Rumack Matthew nomogram)
Indications for acetylcysteine administration
- suspected single ingestion of > 150 mg/kg and patient with unavailable concentration
- patient with unknown ingestion time and serum level > 10 µg/milliliter
- patient with history of APAP ingestion and evidence of any liver injury
- patient with delayed presentation (>24 hours) with lab evidence of liver injury
Acetylcysteine dosing
20 hour IV protocol
- initial loading dose of 150 mg/kg IV over 15-60 minutes
- then administer a 4 hour infusion at 50 mg/kg at 12.5 mg/kg/hr IV
- finally administer 16 hour infusion at 100 mg/kg at 6.25 mg/kg/hr IV
72 hour PO protocol
- loading dose of 140 mg/kg PO then 70 mg/kg PO q4h for a total of 17 doses for 72 hours
Kings college criteria
- developed to determine which patients with fulminant hepatic failure should be referred for liver transplant
- PH < 7.3, PT < 100, Cr 3.4 mg/dL with grade 3 or 4 encephalopathy
Diagnostics for alcohol and glycol poisoning
- blood ethanol, methanol, ethylene glycol
- serum osmolality
- CMP
- ABG
Ethanol toxidrome
- CNS depression
- ataxia
- dyarthria
- odor of ethanol
Ethanol metabolism
- Gets broken down by liver enzymes to acetaldehyde and then to acetate
- acetaldehyde is toxic to the liver
- this process also creates free radicals which cause more damage
Ethanol management
- IV fluids
- thiamine (B1) deficiency is common in etoh dependence
— Wernicke’s encephalopathy is under-diagnosed and under-treated - if CNS depression: intubate, gastric lavage if < 1 hour
- charcoal NOT helpful
- observe and hold until sober or etoh is < 100 mg/dL
- watch for delirium tremens
- always assess for intent
Isopropyl management
- examples: rubbing alcohol, solvents for cosmetics
- can cause CNS depression: 2x more potent than ethanol and duration of action is 2-4x times longer than ethanol
- lavage and charcoal if within one hour of ingestion
- IV fluids
- if hypotensive despite treatment, HD to remove acetone
Isopropyl metabolism
Broken down by the liver to acetone
Examples of methanol
Found in wood alcohol, paint thinners, fuel additives