A 72-year-old lady with a long history of COPD is admitted to the ED semiconscious following a seizure. She does not have a history of epilepsy. She has recently had a URTI for which she was prescribed Azithromycin and Amoxicillin/Clavulanate. Her relatives claim that her compliance with medication is erratic.
Her other current medications include:
On examination she was afebrile with a PR of 125/min in Sinus Rhythm. There was no neck stiffness. Her reflexes were brisk and Plantar responses were flexor. Her LOC prevented a more detailed neurological assessment.
Causes for seizures are generally pretty broad. Something specific to this patient's case should be offered (only 3 causes were asked for).
What do we know about her?
Thus, a sensible list of differentials may include:
The tachycardia, brisk reflexes and decreased level of consciousness also could suggest that the patient has ongoing status epilepticus, which is now non-convulsive.
Screening tools
Specific tests:
Azithromycin (and most other macrolides) and theophylline are a classical interaction; macrolides inhibit the CYP450 enzymes responsible for theophylline clearance.
General pharmacology:
Some unique pharmacokinetic features:
Some ...undesirable pharmacodynamic features:
Symptoms | Signs | Biochemistry |
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Decontamination
Enhanced elimination
Antidotes
Supportive management
A - the patient will likely need intubation at some stage
B - ventilate them with a slightly higher rate to maintain the compensation for metabolic acidosis
C - they will likely be hypotensive with a large overdose; noradrenaline will be required. They will also have arrhythmias. The college answer to Question 29 from the first paper of 2017 helpfully suggests esmolol or amiodarone.
That's a Gambro Adsorba (300C) charcoal haemoperfusion cartridge. Ideally, you'd actually have one to present the trainee with. As you can see, mine expired in 2011.
It contains 300g of cellulose-coated charcoal. The company claims a 300,000m2 internal surface area.
You prime this thing with 260ml of fluid, and it offers a bloodflow resistance of 20-30mmHg.
The charcoal granules are coated a layer of cellulose approximately 3-5 μm thick. According to the company propaganda, this "drastically reduces the undesired deposition of blood components" and "offers maximum safety against the release of fine particles".
The mechanism of action, in summary:
Disclaimer: the viva stem above may be an original CICM stem, acquired from their publicly available past papers. Or, perhaps it is a slightly altered version of the original CICM stem. Or, it is a completely original viva stem, concocted by the monstrously amoral author of Deranged Physiology for nothing more than his own personal amusement. In either case, because the college do not make the main viva text or marking criteria available, almost everything here has been confabulated. It might sound like a plausible viva and it could be used for the purpose of practice, but all should be aware that it does not represent the "true" canonical CICM viva station.
Barnes, Peter J. "Theophylline." American journal of respiratory and critical care medicine 188.8 (2013): 901-906.
Hendeles, Leslie, et al. "Food-induced “dose-dumping” from a once-a-day theophylline product as a cause of theophylline toxicity." Chest 87.6 (1985): 758-765.
Ehlers, Sally M., Darwin E. Zaske, and Ronald J. Sawchuk. "Massive theophylline overdose: Rapid elimination by charcoal hemoperfusion." Jama240.5 (1978): 474-475.
Hall, Kevin W., et al. "Metabolic abnormalities associated with intentional theophylline overdose." Annals of internal medicine 101.4 (1984): 457-462.
Seneff, Michael, et al. "Acute theophylline toxicity and the use of esmolol to reverse cardiovascular instability." Annals of emergency medicine 19.6 (1990): 671-673.
MILTON, L. McPHERSON, et al. "Theophylline-lnduced Hypercalcemia."Annals of internal medicine 105 (1986): 52-54.
Device characteristics of the Adsorba 300C haemoperfusion cartridge
Holubek, William J., et al. "Use of hemodialysis and hemoperfusion in poisoned patients." Kidney international 74.10 (2008): 1327-1334.
Ghannoum, Marc, et al. "Hemoperfusion for the treatment of poisoning: technology, determinants of poison clearance, and application in clinical practice." Seminars in dialysis. Vol. 27. No. 4. 2014.
Ghannoum, Marc, et al. "Blood purification in toxicology: nephrology’s ugly duckling." Advances in chronic kidney disease 18.3 (2011): 160-166.
Winchester, James F. "Complications of Hemoperfusion." DIALYSIS (2000): 127.