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Zaven Sargsyan

Zaven Sargsyan

Aug 1, 2019
14 tweets

Orthostatic hypotension and vitals: short #tweetorial with a case, couple principles, and a few tips. Here’s the case: A lady, 70, got up to take her plate to the sink, got dizzy, and fell. She often gets dizzy with standing, but it usually passes in a few seconds. 1/13

Check out her vitals below, esp top 3 rows: - what do you think of their timing? - what positioning do you think was used for each set? - anything surprise you about the values? - can you draw any conclusions about the *cause* of orthostasis in this case?
Normal physiology: When we stand up, 0.5-1L of venous blood gets pulled ⬇️ by gravity. Sympathetics (norepinephrine) quickly compensate: alpha-1 squeezes blood vessels to ⬆️ venous return, beta-1 makes heart beat faster and harder. Few more details from @UpToDate if interested:
If compensation fails (BP drops >20/10), either the reflex didn’t work right, or there is such a situation that despite full function, the compensation wasn’t enough. How can we distinguish?
Tip 1: Interpret the heart rate. If BP falls but HR ↔️, orthostasis is more likely from autonomic dysfunction. If BP falls and HR ⬆️, more likely low preload or highly preload-dependent state.
I say “low preload” rather than hypovolemia to help us think beyond dehydration and bleeding. For example, sepsis is a common cause of orthostatic hypotension. Before vasodilation and third-spacing progress enough to cause supine hypotension, you’re orthostatic.
Tip 2: It’s quicker for you to check orthostatics yourself than to (a) request them (b) make a note to follow up on the results (c) follow up on the results (d) need to clarify technique, whether concurrent symptoms, etc Ok, so how do we do it?
Tip 3: Take the first measurement within 1 minute. Remember our lady? She gets lightheaded right after standing, and it passes in seconds. I bet you’ve felt this too. If you wait 3 min, you’ll miss the hypotension. @AlbertoPuig6 wrote about this in @SGIM Forum:
Delayed orthostasis can happen too, so do repeat standing VS a couple min later. Oh, and skip the sitting measurement. It doesn’t really add much. Here is a great one-page guide from the CDC on how to check orthostatics.
Tip 4: Always consider impact of meds. They can cause orthostasis themselves, but can also mess with rules of thumb in Tip 1 when layered over another process. E.g. with BBL, HR might ↔️ even if low preload. By contrast, alpha-blocker could ⬇️BP with ⬆️HR.
Tip 5: Realize limitations of this (and any) test. Baseline orthostatic hypotension is prevalent in elderly, on order of 20% or more, and is often asymptomatic/ inconsequential. Test could be + but unrelated to why you checked.
Back to our case. She had diabetes and bad peripheral neuropathy (similar ddx to autonomic neuropathy). She had been having chills and dysuria a few days. Symptoms improved with fluids/antibiotics. Orthosratic BP drop improved but didn’t resolve.
Summary: tips on orthostatic vitals/hypoTN: - skip the sitting and check the first standing BP within 1 min - BP ⬇️ and HR ⬆️ supports low-preload. HR ↔️ supports autonomic failure. - meds can cause orthostasis or confound VS pattern - orthostasis often an incidental/asx finding
Thanks for reading!
Zaven Sargsyan

Zaven Sargsyan

Internist at Baylor College of Medicine. Alum @BCMHouston and @MGHMedicine. Tweets about medicine and language. Opinions my own.
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