Thread by @caseyalbin

1/Fun fact 4 #neurotwitter

1️⃣Lumbar puncture kit manometers measure the opening pressure in cmH2O.

2️⃣The BTF and other societies talk about concerning intracranial pressures in mmHg (threshold 20-22 mmHg, Guideline dependent).

3️⃣20 cmH2O = ~15 mmHg

4️⃣20 mmHg = ~27 cmH2O

2/
This can get equally confusing in EVDs. At @EmoryNeuroCrit we set the threshold pressures for the EVD (ie EVD @ 5, 10, 15..) in cmH2O.

But, the transducer measures and reports ICP in mmHg.

3/ Confused? Mind blown? Thought of all the pts you were worried had concerningly elevated ICP because their LP pressure was 20 cmH2O?

Join the club.
Mercury vs. Water: An Analysis of Multi-Institutional Survey Data Asse... sciencedirect.com/science/articl…

4/ In ⬆️, when asked "how many mmHg is 20cmH2O?" (n=67 most residents), they got ⬇️. 4 correct.

& it happens in #neurocriticalcare too! W/ some society guidelines changing "exceeded 20 mmHg" to "exceeds 25 cmH2O" -- which is incorrect.

5/ Personally, it took 7 yrs of PG training to think about how mmHg🚫cmH2O & to realize how much these units matter. Anyone else? @EmoryNeuroCrit @EmoryNeurology @namorrismd @jepodell @dbfisch @AaronLBerkowitz
#endneurophobia #neurotwitter #neurotwitternetwork #MedEd #MedTwitter