GoLYTELY? or NoGO? Let’s be real about whole bowel irrigation
February 27, 2010, 2:03 pm
Whole Bowel Irrigation and the Hemodynamically Unstable Calcium Channel Blocker Overdose: Primum non Nocere. Cumpston KL et al. J Emerg Med 2010;38:171-174.
As even its proponents admit, whole bowel irrigation (WBI) with high-molecular-weight polyethylene glycol (PEG) has never been proven to improve clinical outcomes in toxicology patients. Despite this, some physicians argue that the procedure is safe, and recommend that it be considered in cases involving toxins that do not bind well to charcoal, patients who have ingested sustained/delayed/extended-release products, or in body-packers. This important paper, from the Toxikon group in Chicago, reminds us that with WBI — as with just about everything else in medicine — there’s no free lunch.
The paper describes two cases in which administration of WBI was associated with a bad outcome:
Case 1: A 58-year-old man apparently ingested 7.2 g diltiazem extended release, and was hemodynamically stable when he presented to the emergency department 3 hours later. He was lavaged (that’s a whole other topic — don’t get me started), given 50 g activated charcoal, and started on WBI at 2L//h. By the time he became bradycardic and hypotensive 4 hours later, he had received only a total of 2 L PEG because of persistent vomiting. Ten hours after ingestion the patient suffered an asystolic arrest which responded to external pacing. At that time, WBI was stopped when abdominal distention was noted. Thirteen hours after ingestion he developed severe and irreversible hypotension and bradycardia when the pacer failed to capture. Autopsy showed hypoperfused bowel without evidence of infarction, bezoar, or obstruction.
Case 2: A 40-year-old man came to the emergency department 15 minutes after reported ingesting 21 g of verapamil SR. He was hemodynamically stable on arrival and was treated with 100 g activated charcoal and WBI at 2 L/h. Four hours after ingestion he was vomiting and developed hypotension and hypoxia. WBI was stopped and he was intubated. He survived with supportive care and pressors, but developed aspiration pneumonia requiring at least a week in the ICU on a ventilator.
The authors point out most of the studies looking at WBI’s effects on pharmacokinetics are done on volunteers who have ingested small amounts of generally non-toxic markers. However, patients who might conceivably benefit most from the procedure are those who have ingested large amounts of nasty toxins likely to cause hypotension or seizures. There has never been an adequate clinical trial looking at the potential risks and benefits of WBI in this population. Therefore, all the potential benefits of WBI are theoretic, whereas the risks — such as aspiration or gastrointestinal ischemia — are quite real. As a general rule, I find it ill-advised to embrace an intervention with known risks but only theoretic benefits. Certainly, as the authors note, ileus and hemodynamic instability should contradict use of WBI. Unfortunately, even if patients are stable on presentation, they very well may become unstable minutes or hours later. I’ve always believed that with most extended-release overdoses, administering multiple small doses of activated charcoal (25 g q 2 h) is a safer way to approach GI decontamination. In addition, in my experience WBI is almost never carried out successfully with a full dose of 2 L/hour of PEG. Perhaps this is fortunate, given the risks of vomiting and aspiration.
The potential role of WBI in patients who have overdosed on toxins that are not absorbed well to charcoal (iron, lithium) or in body packers remains to be determined.
As a very wise man once said, “Don’t just do something — stand there”!
Full disclosure: I work with the Toxikon group in Chicago and with Steve Aks (one of the co-authors of this paper). Dr. Aks has contributed to this blog. Kirk Cumpston — now in Virginia — was a fellow in our program.