Overview
This lecture reviews the clinical use, dosing, and safety considerations for vasopressin, especially in the management of septic shock, and its role alongside norepinephrine.
Vasopressin Mechanism and Effects
- Vasopressin causes vasoconstriction by narrowing blood vessels, increasing blood pressure.
- It does not directly affect heart rate but may cause reflex bradycardia (decreased heart rate).
- Vasopressin is ineffective without adequate fluid resuscitation.
Clinical Indications for Vasopressin
- Main use is as an add-on agent in vasodilatory (distributive) shock, especially septic shock.
- Never used as a first-line agent or monotherapy for shock.
- Added primarily to norepinephrine (nor epi) to augment effects and decrease norepinephrine dose needed.
Dosing and Administration
- Typical septic shock dose: fixed at 0.04 units/min (some hospitals may use 0.03 or titrate up to 0.1).
- Do not titrate up or down; keep the dose steady until ready to discontinue.
- Discontinue vasopressin once norepinephrine requirement is low (<10 mcg/min, sometimes <5).
- Must be administered via central line to prevent tissue injury.
Safety and Side Effects
- Risk of extravasation and tissue necrosis; antidote is phentolamine.
- Can cause hyponatremia (low blood sodium) due to its antidiuretic hormone (ADH) activity.
Other Indications
- Can be used to control bleeding in esophageal varices if octreotide is unavailable.
- Not discussed for use in diabetes insipidus in this context.
Key Terms & Definitions
- Vasoconstriction — narrowing of blood vessels, increasing blood pressure.
- Reflex bradycardia — compensatory slowing of heart rate in response to increased blood pressure.
- Extravasation — leakage of drug into surrounding tissue from blood vessel.
- Hyponatremia — abnormally low sodium levels in the blood.
- ADH (Antidiuretic Hormone) — hormone that reduces urine output and increases water retention.
- Septic Shock — a type of distributive shock caused by severe infection and systemic inflammation.
Action Items / Next Steps
- Review hospital protocol on vasopressin use and dosing.
- Ensure familiarity with central line administration and management of extravasation.
- Study the clinical guidelines for septic shock management.