Phenylephrine (Neosynephrine)

• stimulates alpha adrenergic receptors resulting in
  • vasoconstriction
  • decreased heart rate 
  • increased peripheral resistance
• used to increase blood pressure

• Bolus dose: 
  • hypotension or shock:  0.1-0.5mg (100-500 mcg) as slow IV direct injection q10-15min 
  • PSVT:  0.5-1mg as rapid direct IV injection q60-90 seconds
• IV infusion: 
  • 0.04-0.18mg/min (40-180 mcg/min), titrated to effect 

• hypovolemia, hypoxemia and acidosis should be corrected concurrently with initiation of therapy
• should be weaned off

• Ventricular tachycardia
• Pheochromocytoma
• Hypersensitivity to phenylephrine or any of its components

• bradycardia 
• arrhythmias
• increased myocardial oxygen consumption; avoid in patients with left ventricular dysfunction
• peripheral or mesenteric ischemia
• acute kidney injury
• headache
• restlessness or excitability
• Phenylephrine is a vesicant. Extravasation of drug may cause tissue necrosis and ulceration (treat with 5-15mg phentolamine in NS - see phentolamine monograph)

Special Risk for Torsades de Pointes (TdP):

Phenylephrine does not prolong the QT interval, BUT has a special risk of TdP because of its other actions; which includes epinephrine-like effects. It should be avoided in patients with Congenital Prolonged QT Syndrome (CLQTS). Physicians with expertise in the treatment of these arrhythmias may prescribe phenylephrine to carefully selected patients with CLQTS.

• phenylephrine + atropine = increased BP and tachycardia
• phenylephrine + halogenated anaesthetics = increased cardiac irritability
• phenylephrine + alpha blocking agents = blockade of vasopressor effect
• phenylphrine + other sympathomimetics = increased risk of toxicity

• IV site
• blood pressure
• heart rate and ECG rhythm
• urine output
• urea, creatinine
• central or mixed venous oxygen saturation
• lactate
• cardiac index if monitored
• SVRI if monitored
• lactate
• changes in skin colour or tempurature
• chest pain

• Epinephrine is a vesicant; ensure line patency before and after administration. Central line should be used when available for bolus dosing.
• May be administered IV direct or by IV infusion by a nurse in Adult Critical Care.
• May be titrated by a nurse in Adult Critical Care.
• Continuous infusions must be administered via central venous access device; in emergency situations may be temporarily infused through a peripheral vasuclar access device until a central venous line can be established.
• Patient requires placement of an arterial line to monitor BP.
• Continuous infusions must be administered by infusion device and the pump library must be enabled.
• Should not be infused via the proximal injectate port (blue) of a pulmonary artery catheter. If this is the only available central venous line, it may be administered through the proximal injectate port but thermodilution cardiac output measurements must not be measured during infusion).