Analysis of discarded blood volume for analytical extraction in ICU

For laboratory sample extraction through catheters, blood volume must be discarded prior to specimen collection to ensure the accuracy of the results.

To analyse the discarded blood volume obtained through vascular catheters, according to type of catheter, professional experience in extraction and hospital in Adult Intensive Care Units (ICU) of the Balearic Islands.

Cross-sectional multicentre descriptive study. Conducted from April to December 2018. Field of study: Adult Intensive Care Units of the Balearic Islands.

296 nurses.

nursing professionals who answered the survey. Data collection instrument: ad hoc, anonymous and voluntary questionnaire. Variables studied: waste volume, type of catheter, sex, professional experience and hospital. Descriptive statistical analysis, standard deviation, coefficient of variation, and non-parametric tests: Kruskal-Wallis and Median test with an CI: 95%, using the SPSS vs20.0 programme.

142 surveys were obtained, 12 hospitals participated: 6 public and 6 private, 72.5% women and 27.5% men. The total mean volume discarded was 5.98ml (± 3.01): peripheral venous catheter (CVP) 5.74ml (± 2.85), arterial cannula 4.37ml (± 2.93), peripheral access central catheter (PICC) 7.34ml (± 3.03) and central venous catheter (CVC) 6.49ml (± 2.99). The medians of waste volume vary greatly between the different ICUs (p <.001). Private hospitals discard larger volumes than public hospitals through CVP: 5.12ml (±2.15) vs. 6.99ml (±2.80) (p=.023), CVC: 5.92ml (±2.58) vs. 7.93ml (±1.71) (p=.026) and PICC: 6.77ml (±2.73) vs. 9.07ml (±2.05) (p=.004).

There is a great variability in the volume of blood discarded, it depends on the hospital. No association was found between the discarded blood and the other variables studied. More conservative extraction techniques should be used.