Management of Bradycardia in the OR

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Management of Bradycardia in the OR

Bradycardia can be defined as a heart rate <60 b.p.m. and/or a rapidly falling heart rate. It is not uncommon for adults under general anesthesia to have a heart rate between 40 and 60 bpm, and may vary secondary to home medications (ie: Beta blockers). Therefore it must be established whether the current heart rate is inadequate for the clinical situation.

Differential Diagnosis¹

“8H’s, 8T’s”

Hypoxia Tamponade Hypervagal Tension Pneumothorax Hypovolemia Trauma Hyperkalemia/Hypokalemia Thrombosis/embolus, pulmonary Hydrogen Ion (Acidemia) Thrombosis,coronary Hypothermia QT prolongation Hypoglycemia Toxins Malignant Hyperthermia Pulmonary hyperTension

Algorithm for management

Vagotonic analgesics (ie: morphine), manipulations that increase vagal tone (ie: valsalva maneuver, carotid massage) and sympatholysis from anesthetic agents (ie: alpha-2 agonists) can precipitate bradycardia or hypotension and require immediate intervention. Earlier pacing is reasonable in the perioperative setting secondary to the different spectrum of causes for bradycardia. Failure to intervene quickly can lead to deterioration and cardiac arrest. Below is a treatment sequence for perioperative bradycardia1.

Bradycardia

• Check surgical field/anesthetic
• Check oximeter, capnometry- rule out hypoxia
• Consider differential…(8H’s,8T’s)
• Signs or symptoms of poor perfusion by the bradycardia? (ie: acute altered mental status, ongoing chest pain, or other signs of shock)
  • NO (adequate BP, perfusion)
    •  Observe/monitor
    • Search for cause
    • Consider cardiology consult
  • Yes (hypotension, low perfusion)If severe hypotension, persistent poor perfusion, or low ETCO2 (<15mm Hg)–> start CPR
    • Administer 100% Oxygen, assist ventilation, open IV fluids, and secure airway
    • Consider 0.5mg atropine IV while awaiting pacer. May repeat to total 3mg. If ineffective, begin transcutaneous pacing.
    • Consider IV bolus Epinephrine 10-100mcg. May start low dose Epi infusion if a response (0.05-0.10 mcg/kg/min) or dopamine (2-10mcg/kg/min)
    • Prepare for transcutaneous pacing: use without delay for high degree blocks (Type II second degree block or 3rd degree AV block)
    • Consider CVL, arterial line

References:

1. Moitra, V et al. Anesthesia Advanced Circulatory Life Support. Can J Anesth/J Can Anesth (2012) 59:586-603.