Center for Advanced Practice


712: Mixed-Methods Process Evaluation of a Respiratory Culture Diagnostic Stewardship Intervention

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Critical Care Medicine

Document Type



Introduction/Hypothesis: Tracheal aspirate (TA) cultures are often collected to evaluate for ventilator-associated infections, despite poor specificity. We developed and implemented a guideline to reduce inappropriate ordering of TA cultures in our PICU, and concurrently conducted a mixed-methods process evaluation to identify barriers to implementation. We hypothesized that fear of a missed diagnosis and hierarchy would be key barriers.

Methods: PICU attending physicians, fellows, and nurse practitioners (NPs) were included. Semi-structured interviews were performed using a standardized interview guide 6-8 months after guideline implementation. Attendings were purposively sampled based on rate of guideline non-compliant cultures per clinical service day, sampling from the highest and lowest quartiles. All PICU fellows and NPs were approached. The Consolidated Framework for Implementation Research was used to generate the interview guide and code responses. All participants provided verbal consent.

Results: The preintervention rate of guideline non-compliant TA culture collection was 2.9/100 ventilator days and post-intervention was 1.6/100 ventilator days. Attendings ranged from ordering 0.9 to 20.2 cultures/100 service days. Five attendings, 4 fellows, and 3 NPs participated. Key themes included: views of the test and antibiotic treatment; influence of provider hierarchy on ordering practices; perceptions of guideline implementation; and standardizing ordering of TA cultures. Attending and consultant preferences were identified as key drivers of culture ordering and antibiotic use by fellows and NPs. In contrast, attendings generally viewed the decision to be made as a team or by non-attending clinicians. All groups viewed the TA culture guideline and standardizing TA culture collection positively, though responses were mixed as to whether ordering practice has changed following implementation. A key barrier was a perception that other clinicians were hesitant to change practice. Fear of missing a patient requiring antibiotics by following the guideline too strictly was reported by some participants.

Conclusions: Hierarchy and group norms were key barriers identified. Diagnostic stewardship interventions should therefore target all provider groups and focus on group culture.


Critical Care, Tracheal Aspirate Cultures, Ventilator-associated Infections



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