Activated Charcoal and Beta Blocker Overdose: Clinical Decision Making and the Risks of Dichotomization

This very nice case report in the current issue of the Annals of the ATS is an opportunity to discuss rational clinical decision making.  The authors did almost everything that I would have done in this case and it is a lovely discussion of this toxidrome and its treatment.  There is just one simple and apparently inconsequential decision that I disagree with and I intend to use it as a springboard to discuss rational clinical decision making.

The young woman had a multidrug overdose including metoprolol succinate, extended release.  She presented in shock.  The authors state "Gastrointestinal decontamination was not performed because her ingestion was suspected to have occurred several hours before admission" [emphasis mine].  I have already in an early post on this blog, discussed the inadequacy of the existing data and experimental models on the timing of charcoal administration, which interested readers can read about here.

Studies of the timing of Activated Charcoal (AC) administration use normal volunteers taking therapeutic doses of drugs (for ethical reasons).  We have inadequate data on the speed of absorption of drugs in people who are shocked or who take very large doses of drugs, or extended release drugs.  To dichotomize the efficacy of AC by a bright line of 30 or 60 or even 120 minutes is a gross oversimplification of reality that belies overconfidence in the existing data and experimental models.  This patient took a large dose of a sustained release medication and at some point became shocked presumably causing splanchnic vasoconstriction.  She also took Tramadol and other medications which may slow gut motility via anticholinergic or other effects.  And there may be other unknowns - other medications she took that slowed absorption of the sustained release metoprolol that we don't even know about.

Logic Based Medicine: The Case of Activated Charcoal

Like all good things, Evidence Based Medicine (EBM), when taken to far, runs the risk of making us overwrought and becoming cliche.  I think we are reaching this point.  Given Ioannidis' meta-research findings that most published research findings are false (does he consider the irony that that may apply to his findings too?) the corrupting and corrosive influence of industry on research programs and guideline construction, the biases of academic researchers intent on grants, prestige and promotions (as well as honoraria to supplement paltry academic salaries - I was there once, and I did it too), and the zealousness of "experts" who wish to interpret the evidence in the form of an edict for all to follow (euphemistically called "guidelines"), and several other disturbing trends, it becomes apparent that in the end we must rely upon our own judgment and logic to discern the proper path to follow.  And so it is with Activated Charcoal (AC) administration, an agent used in overdoses and toxic ingestions that has a remarkable capacity to adsorb ingested substances and theoretically limit their toxicity.  (It is not barbecue charcoal, the photo is tongue-in-cheek.)