Lecture 10 Treatment of Perioperative Hypotension Flashcards
Name five true catecholamines.
Dopamine, norepinephrine, epinephrine, isoproterenol, dobutamine
Name the two most popular sympathomimetics used for peri-operative hypotension.
phenylephrine (direct, hits alpha-1, reflex bradycardia is an issue) and ephedrine (indirect, hits alpha-1 and beta-1, tachyphylaxis is an issue.) Ephedrine should not be used in patients who are taking drugs that inhibit norepinephrine reuptake, such as TCAs, MAO-Is, Cocaine. People who are catecholamine depleted (think Infantry guy after a prolonged firefight or chronic cocaine user) will not respond to ephedrine, since ephedrine requires presence of endogenously produced catecholamines.
What is hypotension used as a surrogate measure for?
Cardiac output and tissue perfusion.
-Low BP suggests a potentially compromised global/regional perfusion
Is there a definitive cut off for hypotension for all ages/health statuses?
No! Different people handle different BPs differently. The same is true for higher BPs.
How do we treat hypotension (first steps)?
- Determine the cause of the hypotension.
- Determine the severity of the hypotension
- Determine what resources you have at your disposal.
What’s the DDx of hypotension? (four categories)
- Hypovolemic hypotension (bleeding out)
- Distributive hypotension (septic)
- pump failure (cardiogenic) hypotension (cardiogenic)
- obstructive hypotension
Are hypotension and shock the same thing?
NO! Though they often co-exist.
Shock occurs in the presence of decreased tissue perfusion.
What are some examples of hypovolemic hypotension?
bleeding, decreased intake, GI or other losses
What are some examples of distributive hypotension?
anaphylaxis, septic shock, neurogenic shock, drug induced (anesthesia inhalation agents)
What are some examples of cardiogenic/pump failure hypotension?
MI, myocardial depression
What are some examples of obstructive hypotension?
tension pneumothorax, cardiac tamponade, massive PE, intracardiac clot/tumor, HOCM
What steps are there to hypotension therapy?
- Address the underlying cause.
- Give fluids first
- Supplement w/ vasopressors for hypovolemic hypotension
- Add vasopressors and (maybe) fluids for vasodilation/distributive hypotension
What are the two commonly used vasopressors we use?
phenylephrine and ephedrine
How are phenylephrine/ephedrine used in ACLS?
They really aren’t. Be sure to consider ACLS during your treatment of your patients, both in the OR and out.
Which (phenyl vs ephedrine) is more potent? Does it matter?
Phenylephrine is 100X more potent, but it doesn’t really apply to these drugs since they are in different categories. (On a slide, so worth making this just in case it’s tested.)