PC3092: Single Pass Albumin Dialysis as Rescue Therapy for Pediatric Calcium Channel Blocker Toxicity

Introduction: Calcium channel blockers (CCBs) are a commonly prescribed medication with the highest degree of mortality with poisoning. Poisoning results in bradycardia, reduced heart contractility, peripheral vasodilation, and hemodynamic collapse. First-line management of CCB poisoning includes fluid administration, intravenous calcium, vasoactive medications, and high dose insulin. Rescue therapy includes lipid emulsion therapy, glucagon, and extracorporeal membrane oxygenation support (ECMO). Here we present a case of life-threatening refractory amlodipine toxicity that salvaged with single pass albumin dialysis (SPAD) in conjunction with ECMO.

Case Description: A 17 year old female presented to an outside hospital after intentional overdose of an estimated ingestion of 500mg of amlodipine. She was intubated and given fluid resuscitation, calcium infusion, and insulin infusion and then transferred to Children’s Hospital & Medical Center (CHMC). During transport, she was started on epinephrine and norepinephrine. On arrival to CHMC, glucagon and sodium bicarbonate infusions were also initiated. Her hemodynamics continued to worsen and veno-arterial ECMO was initiated. Hypotension persisted despite ECMO and high dose epinephrine, norepinephrine, and vasopressin. Lipid emulsion and methylene blue provided only brief hemodynamic improvement.

Dialysis was initiated on hospital day 3 as SPAD to facilitate clearance of amlodipine with an initial albumin concentration of 2.5%. The patient’s hemodynamics stabilized after SPAD initiation. An albumin shortage forced the dialysis concentration to decrease to 1.25% and the patient’s hemodynamics worsened, despite maintaining all other support. After emergent request from another facility, the concentration was increased back to 2.5% resulting in improved clinical status. Between hospital day 5 and 9, all inotropes, SPAD and insulin were stopped. She was decannulated from ECMO on day 11, extubated on day 12, and discharged on day 26 to a rehabilitation center. The only medical complication was a small stroke resulting in visual defects. Figure 1 shows the vasoactive agent dosing and blood pressure related to therapeutic interventions.

Discussion: The choice of therapy for removing a toxic substance depends on its molecular size, charge, binding characteristics, volume of distribution, patient size, and availability of extracorporeal techniques. As CCBs are highly protein bound and have a large volume of distribution, they are poorly removed by conventional methods of dialysis. Currently, EXTRIP guidelines do not recommend using albumin dialysis for CCB toxicity due to lack of clinical pharmacokinetic data, however SPAD has been used for other protein-bound drugs in cases pediatric overdoses, such as methotrexate and phenobarbital, indicating this can work for highly protein-bound drugs.

Conclusion: To our knowledge this is the first description of SPAD with ECMO for pediatric CCB toxicity. For our patient, SPAD was live saving. Further studies are needed to address the pharmacokinetics and evaluate SPAD as a salvage therapy for refractory CCB toxicity.