Regular Feedback May Optimize Blood Culture Sample Volumes in the PICU

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Investigators conclude that a set of simple guidelines is useful in changing clinical practice for obtaining blood from pediatric patients for culture.
Investigators conclude that a set of simple guidelines is useful in changing clinical practice for obtaining blood from pediatric patients for culture.

Interventions that included distributing simple weight-stratified guidelines for recommended blood volume and providing feedback to physicians were effective in optimizing blood volume culture in a pediatric intensive care unit (PICU), according to a study published in the Journal of Pediatric Infectious Diseases Society.

The ideal blood volume required for blood culture from small children is unknown. Although several guidelines propose blood volumes for culture in children, no consensus exists on appropriate weight-based sample volume. In addition, effective interventions that encourage physicians to optimize blood volume taken from patients in the PICU setting have not been defined. As part of a quality improvement project in 2016, continuous monitoring of blood volumes for culture in the PICU took place. Subsequently, interventions were instituted that consisted of distributing simple guidelines regarding optimal blood volume for children in each weight range and providing monthly feedback of blood volume-monitoring results to physicians to optimize the blood volumes taken. 

These guidelines recommended blood volume according to 3 body weight categories: <10 kg, 1 mL per bottle; 10 to 19 kg, 2 mL per bottle; ≥20 kg, 4 mL per bottle. In general, sampling of up to 4% of a patient's total blood volume is considered safe. The aim of this retrospective quasi-experimental study was to investigate the effect of these interventions on optimizing the blood volume inoculated into the culture bottles for blood culture.

A total of 3489 blood culture bottles from patients at the PICU in a tertiary children's hospital in Japan were included in the study. Blood cultures were performed for patients suspected to have a bacterial or fungal infection. Blood weight in the culture bottle was determined by subtracting the initial weight from the bottle weight at laboratory arrival. The study period was divided into 2 categories: the preintervention (July to October 2016) and postintervention (November 2016 to August 2017). The postintervention period was further subdivided into 2 categories: the pre-monthly feedback (November 2016 to March 2017) and post-monthly feedback (April to August 2017).

Between pre-intervention and post-intervention, the median blood volumes and median percentages above the recommended blood volume were similar in the <10-kg body-weight group (P =.28) but increased significantly in the 10- to19-kg group (1.42 vs 2.17 mL and 32.6% vs 64.6%, respectively; P <.001). A similar increase was demonstrated in the ≥20-kg group compared with the <10-kg group (1.60 vs 3.68 mL and 16.4% vs 44.2%, respectively; P <.001). Comparison of the 3 time periods (before intervention and 2 periods after intervention), demonstrated that median blood volume tended to be higher in the later period, except in the <10-kg group (<10-kg, P =.14; 10- to19-kg, P <.001; ≥20-kg; P <.001). The blood volume increased stepwise in the 10- to 19-kg and ≥20-kg groups throughout the study period and converged toward the target blood volume after initiation of continuous feedback to the PICU medical staff.

The compliance rates for target blood volumes from arterial, central venous, and peripherally inserted central catheters and peripheral venipunctures were 69.6%, 68.8%, 64.6%, and 54.9%, respectively (P <.001). Further, blood culture positivity in the bottles in which the recommended volume was achieved tended to be higher than in bottles in which this volume was not achieved (P =.088).

Overall, the investigators concluded, “As found in our study, the results indicated that a set of simple guidelines is useful in changing clinical practice for obtaining blood from pediatric patients for culture.”

Reference

Shoji K, Tsuboi N, Arakawa R, Ide K, Mikami M, Kato A, Miyairi I. Continuous monitoring and feedback optimizes blood volume inoculated into culture bottles in the pediatric intensive care unit [published online July 16, 2018]. J Pediatric Infect Dis Soc. doi: 10.1093/jpids/piy061

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