Thoracentesis and hypotension

[IKnowYouRider]

I'm reading about various Respiratory stuff and it says that if too much fluid it taken out of the intrapleural space during a thoracentesis, then the pt can experience severe hypotension. Can anyone explain why this will happen?

[Mike R, ADN, BSN, RN]

I've argued this with my professor before. I thought that since the fluid being pulled out is not part of the vasculature, it would not affect BP. My instructor's argument was that if you pull large volumes of fluid, the space it displaces shifts and vessels and organs. They expand to fill in the space causing temporary hypotension.

Believe what ever you want, but I wasn't sold

Check out this study done in 2010 that suggest there is no statistical relation between large volume thoras and hypotension:

http://www.ncbi.nlm.nih.gov/pubmed/20175369

[IKnowYouRider]

Thanks for the reply. Since posting I was offered another explanation that suggested if the underlying cause is not treated fluid would again be pulled from the vasculature and if fluids were not actively being replaced it cause hypotension...I couldn't imagine that happening suddenly though.

[NurseLoveJoy88, ASN, RN]

Darn. All my nursing books are in the car so I'm going to respond off my basic nursing knowledge.

Okay person gets thorocentesis to pull off fluid in the lungs. This may cause a fluid shift thus causing hypotension? IDK it made since to me a few seconds ago.

[NurseLoveJoy88, ASN, RN]

Another source I checked stated that hypotension can also be cause my the vasovagal response. d/t the procedure.