Optimizing Blood Culture Volume Collection in Inpatient Pediatrics: A Quality Improvement Study

Purpose/Objectives: Blood cultures are essential for the diagnosis and treatment of sepsis. Studies show blood culture volume significantly impacts yield of blood cultures. The chance of detecting bacteria in a culture increases from 1% to 3% per additional milliliter of blood (1,2). Nationally, blood culture volumes often fall short of both age-based and weight-based pediatric volume guidelines due to patient factors (i.e., dehydration, discomfort) and inconsistent healthcare worker education (2, 3, 4). Weight-based culture volume recommendations were established at our institution’s children’s hospital in 2019. This study aimed to: 1) determine baseline rates of compliance with weight-based recommendations within each inpatient unit; and 2) iteratively institute interventions to promote compliance with recommended blood culture volumes.

Design/Methods: 400 uninoculated Bactec peds plus/f and Bactec plus aerobic/f culture vials were weighed to determine an average tare weight of the bottles. Before intervention, two weeks of culture bottles drawn from all patients ages 0-18 years old were weighed and blood volume collected was estimated by subtracting the average tare weight and converting to milliliters. Collected volumes were compared against volume guidelines based on body weight. We iteratively integrated small group meetings with nursing staff and quality improvement leadership, posters, and magnets over three Plan-Do-Study-Act (PDSA) cycles, as described below (Figure 1). Two weeks of culture bottle weights were collected after the first and second PDSA cycles. The third PDSA cycle is currently underway.

Results: Two weeks of inpatient cultures were weighed at baseline (n=339), after PDSA cycle one (n=314), and after PDSA cycle two (n=303). 81% (276 out of 339) of cultures were found to be underweight at baseline. Of these, 89% (303 of 339) of underweight cultures were collected from children weighing greater than 5kg. Cumulatively, proportion of underweight cultures dropped to 74% (233 of 314) after the first PDSA cycle and 61% (185 of 303) after the second PDSA cycle. Rates of underweight culture volume decreased from 94% to 79% to 68% in the pediatric ED, and from 90% to 65% to 49% in the PICU (Figure 2).

Conclusion/Discussion: Blood volume is the number one modifiable variable to improve yield, with consequences for duration of hospital stay and antimicrobial stewardship. Collecting appropriate weight-based blood volume can improve detection of bloodstream infections. Hospital-wide nursing education is underway and may help to improve blood culturing practices.