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  • Stable or unstable?
    • Is the patient in cardiopulmonary arrest? Initiate ACLS Protocol
    • Assess the airway. Ensure the adequacy of oxygenation and ventilation
    • Assess for hypotension. If patient is hypotensive, immediately communicate with the surgeon and examine the surgical field for possible causes. Then the following steps should be undertaken as necessary:
      • Turn off the anesthetic vaporizer
      • Administer crystalloid bolus as appropriate
      • Administer atropine 0.01 mg/kg
      • Consider epinephrine 10–50 μg IV bolus
      • If necessary, start epinephrine infusion at 2 μg/min and titrate as necessary
    • Consider intraoperative EKG, A-line, CVP monitoring
    • Consider use of external pacemaker (transvenous or transcutaneous)
  • Once patient is stabilized, or if stable, identify cause and treat: identify P waves and QRS complexes (see chapter 5):
    • Each QRS is preceded by a P wave:
      • Sinus bradycardia, sinus pause
    • No P waves are visible:
      • Irregular QRS rate: A-Fib with slow ventricular response
      • Wide QRS: sinoatrial block
    • There are more P waves than QRS complexes:
      • PR getting longer, and then P without QRS: second-degree AV block Mobitz 1 (Wenckenbach)
      • PR constant, occasional P without QRS: second-degree AV block Mobitz 2
      • No relation between P and QRS: third-degree AV block
  • Possible causes:
    • Airway issues:
      • Hypoventilation? Increase respiratory rate and/or tidal volume
      • Hypoxia? Increase FiO2 and/or PEEP
    • Hypotension:
      • See Event below
    • Consider a cardiopulmonary event:
      • Tension pneumothorax
      • Hemothorax
      • Tamponade
      • Embolism—gas, amniotic, thrombus, fat
      • Sepsis
      • Myocardial depression—drugs, ischemia, electrolytes, trauma
    • Pharmacological cause:
      • Volatile agent overdose (or adequate dosing in susceptible patient), induction drugs, succinylcholine (especially if redosing), neostigmine, opioids. Identify drugs given by surgeon (e.g., vasoconstrictors)
    • Vagal reflex:
      • Discontinue stimulation; atropine if needed
    • Undetected blood loss:
      • Obtain additional IV access and replace fluids. Ensure cross-matched blood is available; transfuse as needed
    • Consider other causes:
      • Regional/neuraxial anesthetics: Bezold–Jarisch reflex causing vasodilation + bradycardia up to arrest. Ensure normovolemia; administer epinephrine IV boluses (start 10–50 μg, increase if needed)
      • Surgical factors: IVC compression, retractor placement, pneumoperitoneum


  • Stable or unstable?
    • Is the patient in cardiopulmonary arrest (e.g., ventricular fibrillation, pulseless ventricular tachycardia)? Initiate ACLS Protocol immediately
    • What is the blood pressure?
      • Hypertensive? (Consider hypertensive causes discussed in the section “Hypertension.”)
      • Hypotensive?
        • Reconfirm blood pressure
        • Turn off vaporizers
        • Administer crystalloids appropriately
  • Diagnose rhythm: See Chapters 5 and 16
    • QRS duration <0.08 seconds:
      • Regular: attempt vagal stimulus (carotid massage, ocular pressure, Valsalva, unless contraindicated):
        • Each QRS is preceded by a P wave: SVT
        • There are more P waves than QRS complexes: atrial flutter or reentrant tachycardia
      • Irregular:
        • There are no P waves: A-Fib
        • Each QRS is preceded by a P wave: reentrant tachycardia
    • QRS duration >0.12 seconds:
      • Regular:
        • P not visible, or dissociated from QRS: ventricular tachycardia
        • Each QRS is preceded by a P wave: SVT + BBB
        • There are more P waves than QRS complexes: atrial flutter + BBB or reentrant tachycardia + BBB
      • Irregular:
        • No P waves: A-Fib + BBB
        • There are more P waves than QRS complexes: reentrant tachycardia + BBB
  • Treat:
    • Poorly tolerated tachycardia (altered mental status, shock, chest pain), sinus or otherwise?
    • Sinus tachycardia? Identify cause ...

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