Patients in need of need central lines can often have less than ideal IVC diameters, either because of their disease process or because of their baseline anatomy. Optimizing your chances of success through positioning can make a real difference for both you and your patients.
Ideally, placing your patient in Trendelenberg position or asking a cooperative patient to valsalva would be best. However, if you are unable to make either of those things happen, consider lumbar elevation (see the image below (taken from the paper), option F).
A study published in the American Journal of Emergency Medicine in July 2018 looked at a number of positioning options to consider when Trendelenberg wasn’t an option (also see image below), and found that lumbar elevation increased the size of the diameter of both the IJ and SCV as measured by ultrasound in 30 healthy volunteer subjects. The IJ was increased to 9.8 mm with lumbar elevation from 8.7 mm supine (p=0.001) and the SCV was increased to 10.7 mm with lumbar elevation from 10.1 mm supine, almost significant (p=0.08). Importantly, lifting the legs did NOT increase the diameter of either and trended toward making them smaller.
Looking to brush up on the basics of central line placement? Check out these videos:
Effect of lumbar elevation on dilatation of the central veins in normal subjects. Am J Emerg Med. 2018 Jul 18. pii: S0735-6757(18)30591-6. doi: 10.1016/j.ajem.2018.07.032.