High-Dose Insulin and Glucose Therapy
High-dose insulin with glucose is the best next treatment for this patient with refractory bradycardia and hypotension following diltiazem overdose who has failed initial therapies. 1
Rationale for High-Dose Insulin as Next Step
This patient has already received the standard first-line treatments (fluids, atropine, calcium gluconate) without adequate response, as evidenced by persistent bradycardia and hypotension with ongoing symptoms. The 2017 Critical Care Medicine expert consensus specifically recommends incremental doses of high-dose insulin for patients refractory to first-line treatments when myocardial dysfunction is present (Grade 1D for contractility, Grade 2D for blood pressure). 1
The mechanism is critical here: high-dose insulin has a direct positive inotropic effect on the myocardium, improving contractility independent of calcium channels, which are blocked by diltiazem. 1 This makes it particularly effective when calcium administration has already been attempted without sufficient response. 1
Dosing Protocol
- Initial bolus: 1 U/kg regular insulin IV 1
- Continuous infusion: 1 U/kg/hour, titrated up to 10 U/kg/hour based on hemodynamic response 1
- Concurrent dextrose: 0.5 g/kg/hour (typically 50% dextrose solution) to maintain euglycemia 1
- Mandatory monitoring: Serum glucose every 15-30 minutes initially, serum potassium frequently (risk of hypokalemia) 1
Why Not the Other Options
Dopamine is specifically discouraged in calcium channel blocker poisoning due to inconsistent hemodynamic improvement in case series and should not be used. 1 The expert consensus reached agreement against dopamine use in this setting.
Inamrinone (now called amrinone) is a phosphodiesterase inhibitor that, while having positive inotropic effects, also produces peripheral vasodilation that can worsen hypotension—particularly problematic in this patient who is already hypotensive. 2 It is not mentioned in any of the major guidelines for calcium channel blocker overdose management. 1
Transcutaneous cardiac pacing is reserved for unstable bradycardia or high-grade AV block that is refractory to pharmacologic therapy AND when there is no significant alteration in cardiac inotropism. 1 This patient's problem is not purely electrical—there is myocardial dysfunction causing cardiogenic shock, as evidenced by the hypotension. Pacing will not address the underlying contractility problem and may worsen hemodynamics if attempted prematurely. 1 The consensus recommends attempting transcutaneous pacing first only to avoid wasting time on transvenous pacing if it won't be effective. 1
Additional Vasopressor Support
While initiating high-dose insulin, norepinephrine or epinephrine should be added or optimized for vasopressor support. 1 Norepinephrine is recommended to increase blood pressure in vasoplegic shock, while epinephrine increases both contractility and heart rate. 1 High infusion rates may be required. 1
Critical Monitoring
- Advanced hemodynamic monitoring should be in place 1, 3
- Early echocardiographic assessment to document myocardial dysfunction guides therapy escalation 1, 3
- Continuous cardiac monitoring for conduction disturbances 3
Rescue Therapies if High-Dose Insulin Fails
If the patient remains refractory despite maximized high-dose insulin and vasopressors:
- Lipid emulsion therapy (20% intralipid 1.5 mL/kg bolus, then 0.25 mL/kg/min infusion) 1
- VA-ECMO if available, for refractory cardiogenic shock 1, 3
- Transvenous pacing only after pharmacologic options exhausted and if primarily bradycardic without severe myocardial dysfunction 1
Common Pitfall to Avoid
The most critical error would be attempting pacing before optimizing inotropic support with high-dose insulin. Pacing addresses rate but not contractility—this patient needs both, and the contractility problem must be addressed first. 1