I work in a clinical research area where we give study drugs, usually intravenously, then draw PK's and other drug levels at specific time points following the administration. We have some investigators that say all post-administration blood draws must be done peripherally. While others say that after flushing a CVAD well and discarding some "waste" blood, the CVAD can be used for blood draws. of our patients have very limited peripheral access, so a peripheral blood draw may be impossible. Does any know if using a CVAD can skew any results or not? And if so, how long or how much fluid must go through the CVAD before it is considered alright to use? Thanks for your input.
Hi
A partial answer for your question is available in the paper below:
Article Approaches to Clear Residual Chemotherapeutics From Indwelli...
Check the chapter and references in the thesis below, there are many examples of CVAD and flushing methods, etc.
1.10.1 Blood sampling from central venous access devices. (page 9)
1.10.1.1 The discarded method
1.10.1.2 The reinfusion method
1.10.1.3 The push-pull method
https://openarchive.ki.se/xmlui/bitstream/handle/10616/40150/thesis.pdf;sequence=1
Generally, always sample taken using single-use equipment will be better than any catheter, etc but sometimes it's impossible so important is the implementation of the proper method of flushing, etc. It does not matter whether blood is collected from the peripheral vessels or from the heart chamber, or from large deep tangles of blood vessels (eg. some animal studies). The important thing is whether we can control the contamination of the sample if such a problem could exist.
Should be helpful
Best regards
Tomasz
this is a 'well known' problem, and relates to adherence and 'dead space' volumes, that cannot always be fully flushed, so in essence, i agree that - even in children - the same access to administer and to sample is substandard, even after flushing
In general, the difference between IV and CVAD must be confirmed in animal before human kinetics. In addition, the difference is influenced by the kind of drug.
We must consider it based on scientific data only.
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