Ask Us > Measurement of bupivacaine level in blood after successful lipid rescue following LAST

One hour after a successful 20% intralipid resuce following a LAST event in our institution, a venous blood sample was collected from the patient for determination of serum bupivacaine level. Our facility had to arrange for the specimen to be transported to an outside lab three states away (from Florida to North Carolina!) The specimen was assayed eight days after the LAST event. The laboratory reported the bupivacaine level as 0.5 mcg/ml.

Could the 1-hour delay from the LAST event to the venous blood collection have caused a lowering of the measured bupivacaine level? Could the 8-day delay from blood collection to assay have caused a lowering of the measured bupivacaine level?

Could the bupivacaine sequestered within the lipid phase of the blood have been "hidden" from this measurement, or does this measurement represent an aggregate of free plus protein-bound plus lipid-sequestered bupivacaine?
February 28, 2014 | Unregistered CommenterDavid Breznick MD
Hi David,
In short, 'yes, yes and yes'. for the last question (no pun) the answer depends on the laboratories specific method of preparation. Typically howerver, only plasma is likely to have been sent to the outside lab and they are very unlikely to have processed it further (eg ultracentrifuging) to separate lipid-bound bupivacaine. So lets assume that the value was from total plasma. NOte, However, I think the reported concentration is quite reasonable since the acute toxicity reflects the concentration that washed (very temporarily) through the coronary circulation and not the plasma level equilibrated from all organs an hour later. That is, even a small amount of LA into the circulation can create enough of a spike in tissue (cardiac) concentration to trigger a severe, even fatal arrhythmia. anyway, important to know that you didn't have a huge intravascular injection. More important, allow me to encourage you to submit the actual case report!
March 13, 2014 | Registered Commenter[Guy Weinberg]