interesting case rounds alyssa morris emergency medicine r3
TRANSCRIPT
INTERESTING CASE
ROUNDSAlyssa Morris
Emergency Medicine R3
Objectives
DDX for toxin induced seizures
DDX for toxin induced status epilepticus
Indications for pyridoxine
Review methylxanthine toxicity
Review MDAC
CASE
19M took an unknown ingestion and had a seizure.
What is your quick ddx for drugs that cause seizure?
DDX Drug induced Seizure
OTIS CAMPBELL
O- organophosphates
T- TCAI- Isoniazid, insulinS-
sympathomimetics
C- camphor, cocaine
A- anticholinergic, amphetamines, anticholinergic, antidepressants
M- Methylxanthines
P- PCPB- Benzo w/dE- EtOH w/dL- Lithium,
lidocaineL- lead, lindane
DDx-Toxin induced Status
INH
Insulin/hypoglycemic agents
TCA
Theophylline
Wellbutrin
CO
Pyridoxine Indications
INH
Ethylene glycol
Gyromitra Mushrooms
Methylxanthines*
CASE
19M who ingested 112 caffeine tablets (100mg/tab) who was brought in by friend for intractable nausea and vomiting• Total ingestion >11g (175mg/kg)
O/E: P=131,BP= 164/67, T= 37.6, 02= 98%, agitated, vomiting ++
CASE
Labs:• APAP/ASA –• CK 14• Na 140, K 2.2, Cl 101, CO2 17, AG:
22• Lactate 8.8• pH 7.23• Caffeine level 429mmol/L
ECG: Sinus tach, no dysrhythmias
CASE CONT
Continued to be tachy, ++ vomitting, no seizure and no dysrhythmias
Course in ED:• zofran 12mg• Maxeran 10g (still vomiting)• Stemitil 10mg (still vomiting)• MDAC • Central line to replace K+• Zantac 50mg • Ativan 2mg IV x 2
CASE CONT
Labs in am• CK- 2280• PO4 0.29• K- 3.1• Caffeine level 295mmol/L• Lactate 3.9
Still vomiting and agitated
CAFFEINE
Methylxanthine Similar to theophylline
Cause release of endogenous catecholamines Stimulates B1 and B2 R
Structural analogue of Adenosine NE and epinephrine release
Inhibit phosphodiesterase (degrades cAMP) Effects like adrenergic stimulation
PHARMACOKINETICS
Routes: oral, IV, SC, IM, rectal
Oral almost 100% bioavailability
Peak concentration 30-60min
Diffuses readily into total body water and all tissues
Readily crosses BBB
Metabolized by Cytochrome P450 systemActive metabollite is theophylline
TOXICOKINETICS
Range of toxicity varies greatly
No definite conclusions from serum levels can be drawn
Lethal dose estimated: 150-200mg/kg or 5-10g
Death associated serum levels >80mm0l/L Fatalities <200mmol/L Survivial >400mmol/L
OUR PT: 175mg/kg, serum 429mmol/L
CLINCIAL EFFECTS
Occur as a result of:1 Adenosine antagonism2 Release of endogenous
catecholamines3 Phosphodiesterase inhibiton
Toxicity affects: GI system Cardiovascular system CNS MSK
GI
Nausea and protracted emesis
• Severe and difficult to control despite use of multiple anti-emetics
Increase in gastric acid secretion and smooth muscle relaxation
• Gastritis and esophagitis (more common with chronic use)
Transiently elevated liver enzymes
CARDIOVASCULAR
Tachydysrhythmias Sinus tach SVT MAT Afib PVCs VT
MI
Peripheral vasodilation (wide pulse pressure)
Hypertension or hypotension
PULMONARY
Stimulates CNS respiratory centre Increased RR Resp Alkalosis
Respiratory failure
Acute lung injury
CNS
H/AAnxietyAgitationInsomnia
TremorIrritabilityHallucinationsSeizures*
MSK
Increases intracellular Ca++
Smooth muscle relaxation
Tremor
Fasiculations
Myoclonus
Rhabdomyolysis
METABOLIC
HypoK Shift into cells from B2 stimulation
HypoMg
HypoPO4
HypoNa
Hyperglycemia
AGMA (lactate)
MANAGEMENT
Basics: IV, monitored bed
Labs to followextended electrolytesLactateCK
+/- Serum caffeine level
CXR, ECGs
TREATMENT
MDAC*
Emesis Zofran, maxeran
Dysrhythmias Benzos Esmolol Lidocaine
Rhabdo Fluids and monitor u/o
TREATMENT
Electrolytes Replace, but careful b/c will become
hyperK when shift back out of cell
Hypotension Fluids Not dopamine
Seizures Benzos Phenobarb Pyridoxine
MDAC
Definition: more than 2 sequential doses of AC• In many cases, the number of doses
administered is substantially greater
MDAC serves 2 purposes:1 Prevent ongoing absorption of a drug
that persists in the GIT
2 Enhance elimination by either disrupting enterohepatic recirculation or by enteroenteric recirculation
General Indications
GI decontamination for drug or poison ingestion associated with significant risk of toxicity, where supportive care/antidote alone is insufficient to ensure a satisfactory outcome
The toxin must be able to bind to AC
Must believe that a significant amount of agent is unabsorbed and is amenable to removal
AACT Position Statement
Position statement states use MDAC only for ingestions of CarbamazepineDapsonePhenobarbitalQuinineTheophylline /Methylxanthines
Other Drugs
Shown to increase elimination of:DigoxinPhenobarbitalCarbamazepin
ePhenylbutazon
eDapsoneNadolol
TheophyllineSalicylateQuinineCyclosporinePropoxypheneNortriptylineAmitriptyline
Contraindications
Any contraindication to single-dose activated charcoal • AC known not to adsorb • Airway protective reflexes are
absent or expected to be lost and pt is not intubated
• GI perf (esp caustic ingestion)• Increases severity of injury
(hydrocarbons)• Endoscopy for dx/mx anticipated
Presence of ileus
Administration
Initial dose• 1g/kg or 10:1 ratio of ACT:toxin, whichever
is >
Repeat dose • 0.25-0.5mg/kg every 1-6hrs
Procedure• Can be administered with cathartic for
the 1st dose only• If pt vomits, repeat the dose• Can use oral, NG or OG route
*Sxn tube before removal to reduce aspiration risk
SUMMARY
DDX for toxin induced seizures OTIS CAMPBELL
Refractory seizures in toxic ingestion Think about pyridoxine
Caffeine is a methylxanthine Adrenergic stimulation Can get refractory seizures MDAC is indicated