Intravenous Phenylephrine

Aka: Intravenous Phenylephrine, Intravenous Neo-Synephrine, Phenylephrine, Neo-Synephrine

1. See Also
   1. Septic Shock
   2. Intranasal Phenylephrine
2. Indications: Hypotension (intravenous)
   1. Emergency Resuscitation for cardiovascular collapse while performing other interventions
      1. Example: Septic Shock refractory to fluid Resuscitation, temporizing while obtaining central access
      2. Can be used via peripheral IV for hours until central access is available for other pressors (e.g. Norepinephrine)
   2. Conscious Sedation
      1. Commonly used by anesthesiology for Hypotension secondary to Propofol and other agents
3. Mechanism: Intravenous
   1. Direct selective alpha-adrenergic agonist
   2. Push Dose Pressor (Bolus Phenylephrine)
      1. Vasopressor without direct inotropic (contractility) or chronotropic (Heart Rate) activity
   3. Increases cardiac perfusion via Vasoconstriction and secondary increase in venous return
4. Pharmacokinetics: Intravenous
   1. Onset: 1 minute
   2. Duration: 10-20 minutes
5. Adverse Effects: Intravenous
   1. Local infiltration effects
      1. Less local toxicity to tissue and vascular structures compared with other pressors
   2. Reflex Bradycardia
      1. Unlikely in cardiovascular collapse in which adrenergic response is likely to be strong
      2. Baroreceptor reflex to increasing BP is typically outweighed by a stronger adrenergic response
6. Preparation: Intravenous
   1. Dilute 1 ml (10 mg) from Phenylephrine vial (10 mg/ml) in Normal Saline 100 ml bag
   2. Resulting solution: Phenylephrine 100 mcg/ml
   3. Draw solution into labeled syringe for use as Push Dose Pressor
7. Dosing: Intravenous
   1. Phenylephrine (100 mcg/ml) 50 to 200 mcg (0.5 to 2 ml) every 2-5 minutes
8. Resources
   1. EM-Crit Blog (Scott Weingart)
      1. http://emcrit.org/podcasts/bolus-dose-pressors/
      2. http://emcrit/wp-content/uploads/push-dose-pressors.pdf
   2. NLM Daily Med
      1. http://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?id=23174
9. References
   1. Mattu and Weingart in Majoewsky (2013) EM:Rap 13(4): 9-10