Part of the ICU Emergencies Hub — browse every related guide in one place.
When a cardiotoxic overdose stops responding to fluids, calcium, glucagon, and pressors, the therapy that most reliably turns it around is high-dose insulin. The doses are so far outside normal experience that the biggest barrier is often the team's discomfort with them. ICU nurses are central to HIET because it lives and dies on the monitoring — the insulin is only as safe as the glucose and potassium surveillance running alongside it.
A healthy heart runs mostly on free fatty acids. Under the stress of a calcium-channel-blocker or beta-blocker poisoning, the myocardium shifts to depending on carbohydrate for energy, but the same toxins impair insulin secretion and the heart's uptake of glucose — it is starving in a sea of sugar. High-dose insulin does three useful things: it acts as a direct inotrope improving contractility, it drives glucose into the myocardium to feed the failing pump, and it improves microvascular perfusion. It does all this without needing the beta or calcium channels the poison has blocked, which is exactly why it succeeds where catecholamines fail. Notably, it improves contractility without raising heart rate much and without the added oxygen cost of catecholamines.
Protocols vary by institution and should always be followed locally, but the shape is consistent: an insulin bolus (commonly on the order of 1 unit/kg of regular insulin) followed by a high-rate infusion (typically starting around 0.5–1 unit/kg/hour and titrated upward — sometimes far upward — for effect). This is compared with a typical diabetic DKA drip of roughly 0.1 unit/kg/hour, which is why HIET rates look startling. Dextrose is given alongside: a bolus of concentrated dextrose if the patient is not already hyperglycemic, then a continuous dextrose infusion (often D10 or higher, sometimes requiring central access for concentrated solutions) titrated to keep glucose in a euglycemic target. Potassium is repleted as needed. The endpoint is hemodynamic — improving blood pressure, perfusion, and mental status — not a glucose number.
Hypoglycemia is the most feared complication and it can be profound and delayed. Glucose must be checked very frequently early — often every 15–30 minutes until stable, then spacing out cautiously to hourly. Because calcium-channel-blocker patients often start hyperglycemic, they may need little dextrose at first, then abruptly need a lot as the insulin engages — the transition is a classic moment for a glucose to crash. The dextrose requirement can also persist for hours after the insulin is stopped, so monitoring must continue past the drip. This is the single most labor-intensive part of the therapy and the reason these patients need a high nurse-to-patient ratio.
Insulin drives potassium into cells, so serum potassium falls during HIET. The important nuance: this is usually a shift, not a true total-body deficit, so replacement is done cautiously — typically maintaining potassium in a low-normal range rather than chasing it to high-normal, to avoid rebound hyperkalemia when the insulin is weaned. The guardrails and infusion-rate limits in our IV potassium replacement guide apply, with the added HIET wisdom that a modestly low potassium during the drip is expected and tolerated. Magnesium and phosphate are watched too.
Set the patient up for success before the first bolus: reliable IV access (central line preferred for concentrated dextrose and for the vasoactives that usually run concurrently), a glucometer and a plan for q15–30 minute checks, a potassium replacement plan, and clear documentation that this is a toxicology antidote at toxicology doses so no downstream clinician "fixes" it. Keep a running flowsheet of glucose, potassium, dextrose rate, insulin rate, and hemodynamics — the trends are how the team titrates. Anticipate volume from the dextrose carrier, especially in a patient already getting fluids and pressors, and flag rising edema or oxygenation trouble. Above all, be the person who understands the plan well enough to defend it: HIET saves lives specifically because a nurse kept the glucose from crashing while an alarming dose of insulin did its job.
High-dose insulin euglycemic therapy rescues the poisoned heart in calcium-channel-blocker and beta-blocker overdose by feeding and strengthening a myocardium that has switched to running on sugar it can no longer take up. The insulin doses look like errors but are the whole point; the dextrose infusion and obsessive glucose monitoring are what make them safe; and the potassium fall is usually a shift to tolerate, not a deficit to chase. For the ICU nurse, HIET is a monitoring discipline as much as a medication — the antidote works when the metabolic surveillance around it never lapses.
Related: Calcium-channel-blocker overdose | Beta-blocker overdose | Digoxin toxicity | IV potassium replacement | Hyperkalemia emergency
Get the ICU Notebook
Free investing strategies built for nurses. One email per week, no fluff.
Yes, send it freeNo spam. Unsubscribe any time.