Vasopressors and inotropes
Phenylephrine (Neo-Synephrine) drip
Neo-Synephrine
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Dosing
| Start | 10–35 mcg/min |
|---|---|
| Titrate | By blood pressure, every few minutes |
| Maximum | 200 mcg/min |
| Common bags | 50 mg in 250 mL (200 mcg/mL); 20 mg in 250 mL (80 mcg/mL); 100 mg in 250 mL (400 mcg/mL) |
| Dose units | mcg/min, mcg/kg/min |
Line and administration
- Central line preferred; peripheral is acceptable short term in a large proximal arm vein with frequent site checks
- Extravasation: stop, aspirate, phentolamine 5–10 mg in 10–15 mL saline injected into the area
Watch for
- Reflex bradycardia
- Lower cardiac output: a poor choice in pump failure
- Useful in LVOT obstruction
Phenylephrine: full drug monographIndications, mechanism, pharmacokinetics, cautions and every dose the app lists.
In the one-pagers
- Vasopressors and InotropesReceptors and effects: Phenylephrine: α1 only: ↓ reflex / ↔ / ↑↑
- Airway and RSIThe physiologically difficult airway: resuscitate first: Fluids alone do not prevent collapse: in PREPARE II (Russell, JAMA 2022; 1,065 patients) a 500 mL bolus at induction did not reduce cardiovascular collapse (21.0% vs 18.2%). For most patients the more reliable step is a vasopressor started before induction. Push-dose phenylephrine (50–200 mcg) or epinephrine (10–20 mcg) covers the gap; label
- Pulmonary EmbolismSupporting the failing RV: fluids, drugs, oxygen and the airway: Norepinephrine restores the coronary perfusion gradient without raising PVR (ESC 2019); above about 15 mcg/min it may raise PVR, so AHA/ACC 2026 suggests adding vasopressin or phenylephrine rather than pushing it higher. Dobutamine (2–20 mcg/kg/min, ESC 2019) can raise a low cardiac index once pressure holds but alone can drop BP; AH
- Shock Types at a GlanceFindings and first treatments: Fluids worsen LV cardiogenic shock with a high wedge and crackles. RV infarct is preload-dependent: cautious fluids, no nitrates or diuretics. Bleeding: limit crystalloid; accept SBP 80–90 until controlled, except with brain injury. Neurogenic: phenylephrine can worsen bradycardia.
- Spinal Motion RestrictionSpinal shock and neurogenic shock: Cord injury hides bleeding (no pain or guarding below the level, blunted heart rate, warm skin), so image the chest, abdomen and pelvis before blaming the cord (Consortium 2008). Restore volume without overload, then start a vasopressor. Norepinephrine is the usual choice because it adds β1 rate and contractility to α1 tone; phenylephrine can deepen bradycardia;
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For education and exam preparation only. Follow your institution’s protocols. Study aid: check every dose against your local protocols and medical direction, the bag label and your pump.