Blood volume extracted from the critical patient in the first 24 hours after admission

Hematic auto-management and extraction for arterial line (HAMEL), a blood-preserving arterial line system: an animal study

Invasive arterial line insertion is a common procedure in the intensive care unit ICU; however, it can cause unnecessary blood loss while procuring blood for laboratory tests. To reduce blood loss resulting from flushing out the arterial line dead space, we developed a new blood-preserving arterial line system: Hematic Auto-Management & Extraction for arterial Line (HAMEL, MUNE Corp.). Five male three-way crossbred pigs were used to evaluate the necessary amount of blood to be withdrawn before sampling to produce accurate results. We then tested whether the traditional sampling method and the HAMEL system showed non-inferior results for blood tests. Blood gas (CG4 + cartridge) and chemistry (CHEM8 + cartridge) analyses were used for comparison. The total unnecessary blood loss in the traditional sampling group was 5 mL/sample. For HAMEL, withdrawing 3 mL of blood before sampling yielded hematocrit and hemoglobin results within 90% confidence interval of traditional sampling group. Most intra-class correlation coefficients between the traditional sampling and HAMEL system groups were > 0.90. When compared to the traditional sampling method, withdrawal of 3 mL with HAMEL was sufficient before blood sampling. Utilization of the HAMEL system was not inferior to the traditional hand-sampling method. In addition, no unnecessary blood loss occurred in the HAMEL system.

Is minimising waste volume for drawing blood samples in critically ill patients feasible?

INTRODUCTION

Drawing blood samples through a central venous catheter (CVC) is a customary practice in Intensive Care Units (ICUs). It is indicated to discard a volume of waste blood to avoid interference in the results.

AIM

To determine whether a lower discard volume for obtaining blood samples from temporary CVCs placed into the internal jugular, femoral or subclavian vein offers valid results.

METHOD

A quasi-experimental prospective cross-sectional study for which sixty-five patients of over 18 years of age in ICUs, who had been fitted with a triple lumen central venous catheter, were recruited over a period of eight months. Two consecutive blood samples were extracted with tubes for biochemistry, coagulation and hemogram from each patient from the distal lumen. The first sample was obtained with a discarded waste of 1.5 ml from a total extracted volume of 10.2 ml, similar to the usual waste in our ambit (10 ml). Subsequently the second sample was obtained. The paired t-test was used to analyse the data. The Bland-Altman plot and intraclass correlation coefficient (ICC) were used to measure the agreement between methods. The reference change value (RCV) was established as the admissible limit of variation between the pairs of samples.

RESULTS

A total of 65 sample pairs were drawn (intervention-control). The paired t-test found statistically significant differences with a significance level of α = .05 for chlorine (-.536; .012); prothrombin time (-.092; .019) and prothrombin activity (.284; 1.375).The ICC was greater than .9 in all the variables and the limit determined for the RCV was not surpassed by any value.

CONCLUSIONS

The results show the reliability of the blood samples drawn with a discard volume of 1.5 ml.

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.

OBJECTIVES

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.

METHOD

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

POPULATION

296 nurses.

SAMPLE

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.

RESULTS

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).

CONCLUSIONS

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.

Concordance of the ions and GAP anion obtained by gasometry vs standard laboratory in critical care

OBJECTIVE

To evaluate the differences observed in ion and GAP anion determinations obtained by point-of-care (POC) blood gas versus laboratory biochemical testing, and to analyze the possible errors according to the limits of normality.

MATERIAL AND METHODS

A descriptive, cross-sectional retrospective study was made to assess concordance between two diagnostic tests in patients admitted to the Critical Care Unit of Ourense University Hospital Complex (Spain), between July and November 2015, involving at least one coinciding biochemical test and POC determination. Patients under 18years of age were excluded.

RESULTS

A total of 1,073 samples were analyzed. Lin's concordance correlation coefficients for sodium, potassium and chlorine were 0.87, 0.84 and 0.72, respectively. Kappa concordance of the normality limits for sodium, potassium and chlorine was 0.63, 0.74 and 0.32. The results indicated poor correlation of the anion GAP and null concordance between POC and biochemical testing, including the value corrected for albumin.

CONCLUSIONS

Poor concordance was observed between the ion values as determined by biochemistry and blood gases; the two methods are therefore not interchangeable. Kappa agreement with normality limits was good for sodium and potassium, and weak for chlorine. Possible validity was noted in orienting the classification within the ion limits, with the exception of chlorine. No agreement was recorded in relation to the anion GAP, even that corrected for albumin.