SAS, Episode 1: Calcium Channel Blocker Overdose

Recently, I took care of my first patient with a major calcium channel blocker (CCB) overdose. He was a middle aged man with unknown past medical history who had reportedly taken 20 tablets of diltiazem 120mg ER in a suicide attempt. Initial blood pressure in the field was 60/32, heart rate 30-40s. Knowing on an abstract level how sick these patients can get is one thing. Seeing it firsthand is something else entirely. Here are some lessons learned from a harrowing toxicological encounter.
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1. Resist the urge to panic. This was by far one of the sickest patients that I've ever seen. Refractory shock, altered mental status, agitation, erratic blood sugars. When the CMED call comes in, center yourself, run your list and make sure you have the resources you need, because you'll be in that room for the foreseeable future. You'll need a plan for how to cover other acutely ill patients under your care. Keep calm, anticipate possible interventions (and the requisite equipment), and prep your team (especially your primary nurse).
2. 1-800-222-1222. Speaking of asking for help, the mind of an experienced EM-trained toxicologist is just a phone call away. Although most EM practitioners are comfortable with a tylenol, opioid or benzodiazepine overdose, this is the kind of case where you should have a toxicologist whispering in your ear. There's a great deal happening at once and it's near impossible to step away from the bedside to look up the myriad interventions you'll be pursuing. A poison control consultation can help guide you through a tricky set of treatments and counsel you on the most challenging parts of the case, such as whether to give lipid emulsion therapy or transfer to an ECMO center.
3. Just put the central line in. ​The situation is almost certainly going to get worse before it gets better, and you need access. You know right out of the gate that you'll be giving: 1) IV calcium in high doses, 2) high-dose vasopressors, 3) large volumes of IV fluid and 4) a multitude of other drugs (see below). Ergo, a central line is practically guaranteed. In my experience, I've been lulled into a universe of easy peripheral access. Our nurses are outstanding at blind PIVs. Need volume? A 14-18g will do the trick. Need pressors? Well, low dose peripheral pressors are ok (for a while). Tough access? Grab the ultrasound machine. But in the sick calcium channel blocker overdose patient you've immediately committed yourself to 4 or more drips (plus high dose pressors and high volume). You're best served by walking into the room with a plan to drop a line (and a kit in your hands).
4. Do everything. In emergency medicine, we are used to acting quickly based on limited information, but we also tend to want to observe the effect of our interventions prior to pursuing more aggressive ones. This is one clinical scenario in which multiple simultaneous interventions are recommended. These include:
   1. IV crystalloid - bolus 500cc-1L, repeat as needed
   2. ​Atropine - 0.5-1mg IV up to 3mg
   3. IV calcium - 10 to 20mL of 10% calcium chloride over 10 minutes (via central line), repeat up to 4 times every 20 minutes OR 30 to 60 mL of 10% calcium gluconate
   4. Glucagon - 5mg IV bolus, repeat 2 times every 10 minutes up to 15mg total
   5. Vasopressors - Levophed (norepinephrine) is the pressor of choice.
   6. High-dose insulin. And I mean, really, high-dose insulin. Half the battle will be convincing yourself and your staff that it's OK to bolus 100 units of regular insulin IV in a non-diabetic patient. Insulin causes a positive inotropic effect in CCB toxicity and counteracts the refractory hyperglycemia produced in such overdoses. So,
      1. ​If blood sugar is < 150, give D50; replete K;
      2. Bolus 1u/kg regular IV;
      3. Give continuous insulin 0.5/kg/hr IV, max 10u/kg/hr;
      4. Titrate to euglycemia with 5-10% dextrose.
   7. End of the Line. ​If nothing is working, then the following are your final stops in addressing a CCB overdose:
      1. ​​Intralipid (IV lipid emulsion). 1-1.5 mL/kg of 20% lipid emulsion solution. This should be done in consultation with a toxicologist. (An important aside: ​hemodialysis is not effective in these cases)
      2. Transcutaneous / transvenous pacing / aortic balloon pump. Given that these overdoses can produce a refractory mixed shock, you may need to try pacing in some form or get an interventional cardiologist on board.
      3. ECMO. If all else fails, extracorporeal membrane oxygenation is an option, but may require transferring a highly unstable patient to an ECMO center. Additionally, one caveat I learned in the course of caring for this patient, is that you cannot give intralipid and then place them on ECMO as it causes problems with the circuit.
5. ​Get to the ICU. These patients will be extremely resource intensive for the entire duration of their ED course. In this case, my patient needed one-to-one nursing (often with the help of 1-2 additional nurses) and I was physically in the room for nearly the entire time. It was fortunate that I was in a place and at a time of day where this was possible. But if resources are tight or coverage is light, this patient could quickly tax the department as a whole. The interventions you'll be applying are also numerous and dynamic in nature. This is exactly what the ICU exists for and you should hyper-aware of disposition for these patients. You need to protect your patient and your department by getting them to a high level of care as quickly as possible.

Fortunately, this patient did well and ultimately did not need any 'end-of-the-line' therapies. This was a challenging yet valuable first brush with one of the sickest of all types of overdose patients. Like all difficult cases in the ED, teamwork and good communication were the bedrock of successfully managing the overdose.