Anaes Vivas · Anaesthetic adjuncts
Data viva — noradrenaline among the vasopressors
A data viva on noradrenaline placed against adrenaline, phenylephrine and vasopressin. The discriminating data points: noradrenaline is alpha-dominant (alpha-1 plus beta-1) with NO beta-2, raises SVR and blood pressure with reflex bradycardia, maintains cardiac output (better than phenylephrine because of the beta-1 component), and has a half-life of about 2 to 3 minutes so is infusion-only via a central line (taught kinetics). It is the recommended first-line vasopressor for restoring arterial pressure in septic shock (Hiroto 2026). Adrenaline differs by having beta-2 (tachycardia, bronchodilation, lactate rise). Phenylephrine is pure alpha-1 and may reduce cardiac output. Vasopressin acts on the V1 receptor and is a catecholamine-sparing adjunct. The extravasation risk and phentolamine treatment (Shyu 2025), the delirium-null in older adults (Dong 2026) and the airway-in-the-shocked-patient scenario (Ghaffar 2026) support the selection logic.
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A table summarises four vasopressors against five properties:
| Agent | Dominant receptor profile | Beta-2 activity | Heart-rate effect | Cardiac-output effect | Half-life and route |
|---|---|---|---|---|---|
| Noradrenaline | Direct alpha-1 plus beta-1 (alpha-dominant) | None | Reflex fall (bradycardia) | Maintained or slightly decreased | about 2 to 3 minutes; continuous IV infusion, central line preferred |
| Adrenaline | Direct alpha-1, beta-1 AND beta-2 | Yes (potent) | Rise (tachycardia) | Marked rise | about 2 to 3 minutes; infusion or bolus |
| Phenylephrine | Pure direct alpha-1 | None | Reflex fall (bradycardia) | May decrease | about 5 to 10 minutes; bolus or infusion |
| Vasopressin | V1 vasopressin receptor (non-adrenergic) | None | Minimal direct effect | Minimal direct effect | short half-life; infusion (adjunct, taught — no kinetic primary in-file) |
Interpret the table and justify the clinical selection of vasopressor for each of the following scenarios: septic shock, anaphylaxis, perioperative hypotension where a rise in heart rate is undesirable, and a septic shock patient refractory to the first-line agent. Half-lives and routes are taught kinetics; first-line and catecholamine-sparing framing per Hiroto 2026.[7]
References5ShowHide
- [1]Yahya R, et al. First-line vasopressor therapy in neonates with fluid-refractory septic shock. Am J Emerg Med, 2026.PMID 42361705
- [2]Dong T, et al. Vasopressor Selection and Postoperative Delirium in Older Adults. Semin Cardiothorac Vasc Anesth, 2026.PMID 42359892
- [4]Shyu D, et al. Overview of Peripheral Vasopressor Use in an Academic Health System. Ann Am Thorac Soc, 2025.PMID 40126143
- [5]Ghaffar S, et al. Physiological difficult airway management in the emergency department. JPMA, 2026.PMID 42363338
- [7]Hiroto G, et al. Optimizing Timing and Dose of Starting Norepinephrine and Vasopressin in Septic Shock. Life (Basel), 2026.PMID 42355442