1. 2005 update on management of poisoning
Kent R. Olson, MD
Medical Director, SF Division
California Poison Control System
UC San Francisco

2. Case A 16 year old boy with nausea and vomiting
Broke up with his girlfriend last night
“Might have taken some aspirin”
HR 100/min BP 120/70 T 98.6 F RR 12
Exam unremarkable
Na K Cl HCO3 22
Salicylate = not detectable
UTox = negative

3. Acetaminophen ingestion
Often overlooked
Hx incorrect or not available
Hidden ingredient in many drugs
Nonspecific symptoms (N/V)
Initial labs usually normal

4. Acetaminophen Metabolism
Glucuronidation
(non toxic)
Sulfation
(non toxic)
~ 5%
NAPQI
N-acetylcysteine (NAC)
Glutathione + NAPQI
= nontoxic product
Liver cell damage

5. NAC treatment Best if started within 8 hours of ingestion
However, late treatment still beneficial
Vomiting often complicates PO dosing
Use antiemetics?
Give via NG tube?
Give the NAC intravenously?

6. So what’s new? IV acetylcysteine Duration of treatment Other tidbits:
Acidosis early after ingestion
Early (transient) elevated INR

7. IV acetylcysteine
Conventional product (Mucomyst) not FDA approved for parenteral use
But, can be given IV via micropore filter
New, approved IV product = Acetadote™
Advantages?
Side effects?

8. IV acetylcysteine
Both products can cause an anaphylactoid reaction (flushing, hypotension)
May be infusion rate related (despite recent report in Ann Emerg Med 2005 Apr;45(4):402-8)
We recommend giving initial loading dose more slowly (45-60 min versus 15 min)

9. Oral or IV? < 7 hours after OD
Use oral dosing regimen if not vomiting
Switch promptly to IV if begins vomiting
> 7 hours after OD
Start IV dosing immediately
Either product is okay
Can give first dose IV then switch to PO

10. How long to treat? Conventional US protocol was 72 hours
Shorter regimens have proven effective
We have used hours for years
Europeans have always used 20 hrs
Acetadote uses 20-hour IV infusion
Bottom line:
20 hours IV or PO okay in most cases
Treat longer if evidence of liver toxicity

11. Other acetaminophen tidbits
Acidosis early after ingestion
Usually with levels > mg/L
May also see early coma, hypotension with acute massive overdose
Not secondary to liver failure
Transient early rise in PT/INR
First 24 hrs

12. Case 55 yo man found unresponsive in his bedroom
Charcoal stove was being used to heat the room
Wife experiencing severe headache, dizziness, nausea

13. Carbon monoxide poisoning
Suggested by Hx of charcoal stove use, more than one victim with ALOC
Other clues?
“Cherry red” skin color - not reliable
pO2, pulse oximetry usually normal
Sx are often nonspecific, flu-like

14. Treatment of CO poisoning
Initial: highest available flow oxygen
15L nonrebreather or
ET intubation and 100% oxygen
What about hyperbaric oxygen? (HBO)
Potentially more rapid CO removal
Can it prevent CNS damage?
Persistent neurological damage
Delayed neuropsychiatric sequelae

15. HBO vs normobaric oxygen
Scheinkestel 1999 Med J Aust 170:203
Randomized, double-blind, placebo-controlled using “sham” HBO
No difference in outcome, in fact HBO group did slightly worse
Weaver 2002 NEJM 347:1057
Also RCCT, double-blind
Showed slight advantage with HBO

16. So: HBO or NBO?
Issue remains unsettled, but consideration of HBO is now suggested when . . .
Hx of loss of consciousness
Older or pregnant patient
Presence of metabolic acidosis
COHgb level over 25%
Cerebellar findings?

17. Case
65 yo woman undergoing transesophageal echocardiography for evaluation of cardiac thrombus prior to cardioversion
Hx of ASCVD, s/p CABG, HTN, Type II DM, hyperlipidemia, obesity, and atrial fibrillation
Meds: amiodarone, ASA, enoxaparin, glyburide, T4, metoprolol, niacin, rabeprazole, simvastatin, and warfarin

18. Case continued . . During procedure O2 saturation was measured at 90%
After the procedure her pulse ox fell further and she appeared cyanotic despite 100% O2
ABG: pO2 293
J Am Osteopathic Soc 2005; 105:381

19. Methemoglobinemia Oxidized form of hemoglobin
Unable to carry oxygen efficiently
Blood appears “chocolate brown”
pO2 is normal (dissolved O2)
Pulse oximetry usually 88-90%, even with severe MetHgb (eg, 50%)
Treatment: methylene blue

20. Causes of methemoglobinemia
Many poisons and drugs
Any oxidant is a potential cause
Some drugs: dapsone; sulfonamides; nitrites; phenazopyridine (Pyridium); and some local anesthetics
The patient had been treated with a topical anesthetic spray containing benzocaine

21. Case
A 34 year old man is found unconscious, with resp. depression and pinpoint pupils
He awakens rapidly after injection of IV naloxone 0.2 mg
He signs out AMA 15 min after arrival

22. Opioid overdose Usually easy to recognize Coma Pinpoint pupils
Respiratory depression
Treatment: naloxone
Start with small doses ( mg) to reduce risk of sudden withdrawal Sx
Observe for at least 3 hrs after naloxone

23. Opioids, continued Methadone Long half-life (20-30 hrs!)
Can see relapse 1-2 hrs after naloxone
Not included in all Urine Tox screens

24. New opioid Buprenorphine (Subutex, Suboxone)
Used in Rx of opioid-dependent patients
Longer duration of action
Partial agonist and antagonist effects
Lower “ceiling” effect makes it less prone to abuse and safer in OD
Can cause acute opioid withdrawal Sx
See

25. (eg, morphine)
lower “ceiling”
(eg, buprenorphine)

26. Case 23 yo woman with confusion, agitation
BP 110/70 HR 120/min RR 26/min T 100
Na K Cl HCO3 16
Glucose 98 mg/dL BUN/Cr 15/0.9

27. Metabolic acidosis “MUDPILES” Methanol, Metformin Uremia DKA
Phenformin, Paracetamol (Tylenol in U.K.)
INH, Iron
Lactic acidosis
Ethylene glycol
Salicylate

28. Salicylate poisoning Acute OD or chronic overmedication
Anion gap acidosis
Hyperventilation
Typical ABG shows mixed alkalemia and acidosis; eg, pH pCO2 18

29. Case, continued
The woman’s roommate brings in an empty bottle of Long’s Drugs brand Aspirin
Bottle originally contained #300
What is the recommended dose of activated charcoal?
300 tabs x 325 mg each = 97.5 gm
Optimal ratio AC:Drug = 10:1
Dose of AC = 975 gm (16 bottles!?!?)

30. Gut decontamination What’s OUT:
Ipecac – except for rare use on scene if hospital more than 60 min away
? Gastric Lavage – unless large, recent ingestion
What’s IN:
Activated charcoal – if it can be given early and airway is protected
Whole bowel irrigation (WBI)

31. Whole bowel irrigation
Balanced electrolyte solution containing non-absorbable polyethylene glycol to maintain normal osmolarity
Can be given at 2 L/hr for hrs-days without change in electrolytes, fluid balance
Indications:
Massive ingestions
SR preparations
Agents not adsorbed by AC (eg, Fe, Li)

32. Potential indications for WBI
Cocaine-filled condoms
Iron pills

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Diagnosis & management
Indications for and use of antidotes, hemodialysis, antivenom
MD-toxicologist back-up
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