Objective: In intensive-care unit (ICU) patients it is common practice to sample blood from central venous lines (CVL). This study was designed to answer the question on how much blood has to be aspirated through the CVL before the actual blood sample is taken to get accurate laboratory findings.
Design and setting: Simultaneous blood samples from a peripheral vein (intraindividual control) and 5-ml portions from a CVL up to 25 ml were analyzed.
Patients: 5 patients of an internal ICU participated in the study.
Results: For the analyzed 24 different parameters it could be shown that after aspirating 10 ml of blood, the results are comparable to analyses from peripheral vein samples.
Conclusions: Although blood sampling from a CVL--after aspiration of 10 ml blood--results in correct laboratory analyses, this procedure leads to a greater amount of blood loss and, hence, cannot be recommended in long-term ICU treatment.