Thursday, March 3, 2016

Code Blue, Hypothermia, and Pressors

Today’s morning report was cancelled as a result of a code blue, which represented an excellent learning experience.  The patient was originally admitted with sepsis, and had a  end-stage renal disease on dialysis.  She had become progressively hypotensive and hypoxic over the previous 24 hours, and was breathing agonally with a very low pressure when the code was called. Upon initiating rhythm monitoring, she was in ventricular fibrillation.  She received high-quality CPR, two shocks, an epinephrine bolus and an amiodarone bolus.  She was intubated with rapid reflux into the ETT of pink, frothy sputum suggestive of decompensated heart failure.  This resulted in a return of spontaneous circulation (ROSC).  As is commonly the case, she remained hypotensive following the arrest, requiring an infusion of dopamine, norepinephrine, and boluses of phenylephrine and epinephrine.

This case has multiple learning points:

·      Code blues are as much about management and leadership than they are about medical knowledge.  Our code leader promptly entered the room, introduced himself and his role, and took control of the situation. The priorities at the beginning of a code are to check for a pulse, organize rhythm and vital sign monitoring, initiate CPR if appropriate, and maintain an airway through bag-mask ventilation and ultimately an advanced airway.  During the code, Mike and the rest of the time exemplified good communication strategies which include the following:
o   Loud and clear introductions
o   Clear sharing of the though process of the code, what the next steps are, and asking for suggestions
o   Closed-loop communication (e.g. “Please give 1mg of epinephrine and let me know when it’s in”) on the part of the code blue leader, and team members
o   Assigning tasks to particular individuals, using names if possible
o   Voicing concerns about safety transporting a patient with unstable vital signs or an unstable airway
·      Given the rapidity of the ROSC, this code blue became more about post-arrest care than about the algorithm itself.  This part of things is less well-taught, because critical care physicians usually intervene at this point.  There a couple of points to mention here:
o   Therapeutic hypothermia (which involves maintaining a core temperature between 32-34C) was recommended for all patients with out-of-hospital VF/VT arrest, and most other comatose patients post-arrest in the 2010 ACLS guidelines.  After multiple trials, the 2015 ECC post-arrest guidelines now recommend a term called targeted temperature management rather than therapeutic hypothermia, largely because prevention of pyrexia (T 36C) has been shown to be equivalent to hypothermia.  The 2015 AHA post-arrest guidelines echo the same thoughts.
o   The guidelines are not specifically clear, but targeted temperature management may mean anywhere from 32C to 36C.  UpToDate suggests a lower temperature selection in patients with deeper coma following arrest (no motor function) and a higher temperature selection (36C) in patients with some motor function but not obeying commands.
o   Pressors are something we don’t use often on medicine, but can be your best friend during a cardiac arrest.  There is a vasoplegia that follows an arrest, so regardless of its cause, you almost always need them.
§  Do you need a central line to use pressors? No.  It is preferred because it allowed infusion of higher concentrations of vasoactive agents, and peripheral IVs tend to extravasate those compounds which can lead to tissue necrosis.  In an emergency without a central line, peripheral pressors is OK.  The fastest way to obtain access if needed is with an intraosseous line.
§  What pressor is the best? That depends on what you want:
·      Phenylephrine (Neosynephrine®) – this is a pure alpha agonist typically used in boluses rather than infusions.  Expect a huge afterload increase, blood pressure rise, and reflex bradycardia.  Make a vial of 100ug/mL by mixing a 10mg vial (how the drug comes) into a 100cc minibag of NS.  Use every 100-500ug every 2-3 minutes.
·      Norepinephrine (Levophed®) – this is our most common pressor infusion and is probably the best for undifferentiated shock.  It has 7:1 alpha:beta effect, and raises pressure with a small amount of inotropy.  It can be mixed in peripheral or central concentrations and has doses of 0-0.35ug/kg/min.
·      Dopamine – this is premixed on crash carts and can be given through a peripheral IV.  Depending on the concentration, it has different effects.  Very low doses (“renal dose”) are classically associated with increased renal perfusion and reductions in BP.  As doses increase, beta effect predominates, and at doses over 20ug/kg/min, alpha effect predominates.
·      Epinephrine – acts on all receptors.  Premixed in 1:10,000 (code vials of 1mg).  This gives you equal alpha and beta effect and is great for patients with bradycardia.  Use a full milligram ONLY for a pulseless patient.  Use 100-200ug (1-2cc) of the code vial for a quick increase in blood pressure and heart rate.  Infusions can be used for bradycardia at 1-10ug/min.
·      Others such as dobutamine (Dobutrex®), isoproterenol (Isuprel®) and vasopressin are used in specific situations (see reference below from Overgaard et al).
Further Reading:
Overgaard, C. B., & Džavík, V. (2008). Inotropes and vasopressors review of physiology and clinical use in cardiovascular disease. Circulation, 118(10), 1047-1056.

Peberdy, M. A., Callaway, C. W., Neumar, R. W., Geocadin, R. G., Zimmerman, J. L., Donnino, M., ... & Hoek, T. L. V. (2010). Part 9: Post–Cardiac arrest care 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation, 122(18 suppl 3), S768-S786.

Holzer, M. (2010). Targeted temperature management for comatose survivors of cardiac arrest. New England Journal of Medicine, 363(13), 1256-1264.

Link, M. S., Berkow, L. C., Kudenchuk, P. J., Halperin, H. R., Hess, E. P., Moitra, V. K., ... & White, R. D. (2015). Part 7: Adult Advanced Cardiovascular Life Support 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation, 132(18 suppl 2), S444-S464.

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