June 15th, 2014

The hypotensive and bradycardic patient

By Daniel Cabrera, M.D.

Notes from Ben Sandefur Grand Rounds "The hypotensive and bradycardic patient"

By Damian Baalmann, M.D.

sandefur1

Broad Differential for Hypotensive + Bradycardic Patient

  1. Toxic
    1. CCB
    2. Beta Blocker
    3. Cardiac Glycodisde (Digoxin)
    4. Alpha-2 Agonist (Clonidine)
    5. Organophosphate
  2. Cardiac
    1. Cardiac Conduction Disease
      1. Infarction
      2. Primary Conduction Disease
      3. Pacemaker Failure
      4. Infectious: Lyme Carditis/ Chaga’s Disease
  3. Electrolyte
    1. Hyperkalemia
  4. Endocrine
    1. Hypoadrenalism
    2. Hypothyroidism
  5. Environmental
    1. Hypothermia
  6. Gastrointestinal
    1. Massive GI Bleed (vaso-vagal response)
  7. Neurogenic
    1. Neurogenic Shock

  • Remember that often the presentation is multifactorial. Additionally, bradycardia + hypotension is often the final common pathway for dying patient, regardless of etiology.

Calcium Channel Blockers

  • Classic Non-Dihyhdropyridine CCB overdose: Hypotensive, Bradycardic, and Hyperglycemic

Beta-Blockers

  • Pharmacology: G-Protein Linked Receptor→Adenylyl cyclase→cAMP→PKA
  • Beta-Blocker Overdose: Hypotensive, Bradycardic, Hypo- or Normoglycemic
    • CNS effects with propranolol (b/c it crosses the BBB)

Therapeutic Options for CCB or Beta-Blocker Toxic Patient

  • Give Calcium!
    • Calcium Gluconate: PIV, dose: 3-6g
    • Calcium Chloride: Central access, dose: 1-2g
  • Glucagon
    • Activates G-protein and bypasses B-blocker
  • Amrinone
    • Increases cAMP in the cell
  • Vasopressors
    • Works on Beta receptor
  • Insulin
    • Overcomes hypoglycemia of CCB
    • Glucose entry in the Myocytes →increase ionotropy
    • Bolus 1U/kg, infusion 1-10U/kg/hr, D10 @100mL/hr, replete K+, avoid vasopressors
  • Intralipid Therapy
    • 1.5 mL/kg of 20% solution of 2-3min; 0.25-0.5 mL/kg/min drip for 30-60 min
    • Data not quite as robust as hyperinsulinemia therapy
  • Also think of Transvenous Pacemaker, Intra-aortic balloon pump, ECMO, Cardioplumonary Bypass

Summary

  • Think broadly with differential of hypotension and bradycardia
  • Animal data strongly supports using insulin for increasing survival in CCB and beta-blocker; vasopressors ↑SVR and may be counterproductive
  • Glucagon, Vasopressors, and Amrinone all display tachyphylaxis because they rely on cAMP pathway which eventually is depleted
  • Consult Poison Control Center Early: 1-800-222-1222
  • High-dose insulin therapy has emerged as an effective therapy for CCB and beta-blocker toxicity
  • Lipid Emulsion Therapy may be helpful in cardiotoxicity or cardiac arrest from lipophilic cardiotoxic medications, but the data is not as compelling

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