OBJECTIVE: To conduct a process evaluation of a respiratory culture diagnostic stewardship intervention.

DESIGN: Mixed-methods study.

SETTING: Tertiary-care pediatric intensive care unit (PICU).

PARTICIPANTS: Critical care, infectious diseases, and pulmonary attending physicians and fellows; PICU nurse practitioners and hospitalist physicians; pediatric residents; and PICU nurses and respiratory therapists.

METHODS: This mixed-methods study was conducted concurrently with a diagnostic stewardship intervention to reduce the inappropriate collection of respiratory cultures in mechanically ventilated children. We quantified baseline respiratory culture utilization and indications for ordering using quantitative methods. Semistructured interviews informed by these data and the Consolidated Framework for Implementation Research (CFIR) were then performed, recorded, transcribed, and coded to identify salient themes. Finally, themes identified in these interviews were used to create a cross-sectional survey.

RESULTS: The number of cultures collected per day of service varied between attending physicians (range, 2.2-27 cultures per 100 days). In total, 14 interviews were performed, and 87 clinicians completed the survey (response rate, 47%) and 77 nurses or respiratory therapists completed the survey (response rate, 17%). Clinicians varied in their stated practices regarding culture ordering, and these differences both clustered by specialty and were associated with perceived utility of the respiratory culture. Furthermore, group "default" practices, fear, and hierarchy were drivers of culture orders. Barriers to standardization included fear of a missed diagnosis and tension between practice standardization and individual decision making.

CONCLUSIONS: We identified significant variation in utilization and perceptions of respiratory cultures as well as several key barriers to implementation of this diagnostic test stewardship intervention.

BACKGROUND: Bacterial cultures from tracheal aspirates (TA) and bronchoalveolar lavage (BAL) specimens can be used to assess patients with artificial airways for lower respiratory tract infections (LRTI). TA collection may be advantageous in situations of limited resources or critical illness. Literature comparing these diagnostic modalities in pediatric populations is scarce.

METHODS: Single-center, retrospective analysis of 52 pediatric patients with an artificial airway undergoing evaluation for LRTI. All patients had a TA specimen collected for semiquantitative Gram stain and culture followed by BAL within 48 h. Microbiologic diagnosis of LRTI was defined as a BAL sample with >25% neutrophils and growth of >10 colony-forming units/ml of one or more bacterial species. The test characteristics of TA were compared with these BAL results as the reference standard. Concordance in microorganism identification was also assessed.

RESULTS: Overall, 24 patients (47%) met criteria for LRTI using BAL as the diagnostic standard. TA samples positive for an isolated organism had poor sensitivity for acute LRTI when compared with BAL, regardless of semiquantitative white blood cell (WBC) count by Gram stain. Using a TA diagnostic threshold of organism growth and at least "moderate" WBC yielded a specificity of 93%. Positive predictive value was highest when an organism was identified by TA. Negative predictive value was >70% for TA samples with no WBC by semiquantitative analysis, with or without growth of an organism. Complete concordance of cultured species was 58% for all patients, with a higher rate seen among those with endotracheal tubes.

CONCLUSIONS: The role of cultures obtained by TA remains limited for the diagnosis of acute LRTI as demonstrated by the poor correlation to BAL results within our cohort. Optimal strategies for diagnosing LRTI across patient populations and airway types remain elusive.

<p><strong>OBJECTIVE: </strong>To evaluate clinical applications of Dual-Energy CT (DECT) in pediatric-specific lung diseases and compare ventilation and perfusion findings with those from single-photon emission CT (SPECT-CT) V/Q.</p>

<p><strong>METHODS: </strong>All patients at our institution who underwent exams using both techniques within a 3-month period were included in this study. Two readers independently described findings for DECT, and two other readers independently analyzed the SPECT-CT V/Q scan data. All findings were compared between readers and disagreements were reassessed and resolved by consensus. Inter- modality agreements are described throughout this paper.</p>

<p><strong>RESULTS: </strong>Eight patients were included for evaluation. The median age for DECT scanning was 3.5 months (IQR=2). Five of these patients were scanned for both DECT and SPECT-CT V/Q studies the same day, and three had a time gap of 7, 65, and 94 days between studies. The most common indications were chronic lung disease (5/8; 63%) and pulmonary hypertension (6/8; 75%). DECT and SPECT-CT V/Q identified perfusion abnormalities in concordant lobes in most patients (7/8; 88%). In one case, atelectasis limited DECT perfusion assessment. Three patients ultimately underwent lobectomy with corresponding perfusion abnormalities identified by all reviewers on both DECT and SPECT-CT V/Q in all resected lobes.</p>

<p><strong>CONCLUSION: </strong>DECT is a feasible technique that could be considered as an alternative for SPECT-CT V/Q for lung perfusion evaluation in infants. This article is protected by copyright. All rights reserved.</p>