Endotracheal aspirate cultures (EACs) are commonly obtained in the evaluation of suspected ventilator-associated infections (VAIs),Reference Willson, Hoot and Khemani1 an important cause of nosocomial infections.Reference Grohskopf, Sinkowitz-Cochran and Garrett2 Overutilization of EACs may contribute to overtreatment for VAI because EACs cannot distinguish between bacterial colonization and infection,Reference Durairaj, Mohamad and Launspach3, Reference Willson, Conaway, Kelly and Hendley4 and positive EAC results prompt treatment with antibiotics.Reference Willson, Hoot and Khemani1, Reference Venkatachalam, Hendley and Willson5, Reference Willson, Kirby and Kicker6 EAC utilization and interpretation of results are subject to site-specific variability.Reference Willson, Hoot and Khemani1 As part of a quality improvement project, we aimed to better understand local practices as a formative step in the development of a guideline to standardize EAC utilization in the pediatric intensive care unit (PICU).
Methods
We prospectively identified a convenience sample of EACs obtained from mechanically ventilated patients (endotracheal tube or tracheostomy) from November 21, 2017, to February 4, 2018, in the Johns Hopkins Children’s Center PICU. We surveyed clinicians caring for patients with EACs using a 2-part written survey comprised of 10 multiple-choice or Likert-scale questions (see Supplement 1 online). Survey part 1 was distributed within 1–2 days of EAC collection to capture clinicians’ reasons for and expectations of the culture results. Survey part 2 was distributed 5 days after EACs were conducted to examine how the results contributed to patient management. We defined VAI as clinician-diagnosed ventilator-associated pneumonia or tracheitis because these entities are often treated interchangeably.Reference Gauvin, Dassa, Chaibou, Proulx, Farrell and Lacroix7, Reference Craven, Chroneou, Zias and Hjalmarson8 We retrospectively performed chart review. Descriptive analyses were completed using Stata version 14.0 software (StataCorp, College Station, TX). The Johns Hopkins Institutional Review Board acknowledged this evaluation as part of a quality improvement project.
Results
Description of EACs and patients
We conducted surveys and reviewed 25 EACs of 107 EACs obtained. The median patient age was 1.0 year (interquartile range, 0.92–5.0), and 52% were female. Overall, 18 patients (72%) had been ventilated for ≥4 weeks and 11 patients (44%) had had a tracheostomy. EACs were collected concurrent with blood cultures for 19 patients (76%), and “pan cultures” (ie, ETA, blood, and urine) were collected for 15 patients (60%). In 23 of 25 cases, the patients had had a previous EAC (92%), and 7 EACs were repeated within 3 days (28%), of which only 1 clinician recalled. The median time to repeat culture was 6 days. Repeated EACs often grew the same or fewer bacteria (n = 17, 72%).
Results of survey part 1: Provider perceptions at time of culture
The completion rate for the 25 two-part surveys was 100%. Surveys were primarily completed by the first-call clinician: the nurse practitioner (72%, two-thirds of first-call providers are nurse practitioners in this unit), resident (22%), or fellow (6%). The team member reported to have suggested an EAC was the nurse (4%), attending physician (15%), fellow (24%), nurse practitioner (32%), or unknown (24%). The most frequent clinical change triggering an EAC was fever (Table 1). Moreover, 11 EACs (44%) were obtained for nonspecific clinical changes (eg, fever alone), and the remainder of cases with EACs had multiple clinical changes consistent with possible VAI (eg, increased secretions, fever, and increased ventilator settings). Clinicians expected that the EAC would help with the diagnosis of VAI (n = 17, 68%) and antibiotic selection (n = 20, 80%). Clinicians reported the expected contribution of EAC to patient management as not at all (n = 1, 4%), a little (n = 9, 30%), very (n = 15, 60%), or essential (none, 0%).
Table 1. Clinician Reported Reasons Prompting Endotracheal Aspirate Culturesa
Note. O2, oxygen; FIO2, fraction of inspired oxygen; WBC, white blood cell count; CO2, carbon dioxide; CRP, C-reactive protein.
a Clinicians were surveyed after 25 endotracheal aspirate cultures were obtained regarding clinical changes that prompted obtaining the culture.
b The survey allowed selecting all possible options, therefore the sum is >25. Overall, 11 EACs (44%) had isolated or nonspecific clinic changes reported: fever alone (n = 4), hypotension alone (n = 2), increase in ventilator settings alone (n = 2), or fever with rising WBC or rising CRP without other clinic changes (n = 3). The other 14 EACs had multiple clinical changes.
Results of survey part 2: Impact of EACs on clinical management
Clinicians reported subsequent value of the EAC data to patient management as not at all (n = 4, 16%), a little (n = 10, 40%), very (n = 7, 28%), or essential (n = 4, 16%). Overall, 10 case patients (40%) were diagnosed with a VAI. In 9 of these cases, the EAC reportedly helped inform the diagnosis, and in 7 of these cases, the bacterial culture result was the most informative component. Following the EAC result, the empiric antibiotic treatment was discontinued in 3 patients (12%), was modified in 4 patients (16%) based on the EAC result, was changed in 5 patients (20%) based on a non-EAC result (eg, urine studies), or was not changed in 13 patients (52%; 2 patients never received antibiotics).
Discussion
The results of part 1 of the survey demonstrate a relatively low threshold to obtain EACs in response to nonspecific clinical changes (eg, fever alone), fever was the primary indication, and EACs were often obtained concurrent with other cultures. The results of part 2 of the survey indicate that most patients were not diagnosed with VAI, that antibiotics were infrequently changed in response to the EAC result, and that more than half of clinicians surveyed subsequently felt the EACs were of little to no help in overall patient management. Notably, the EAC led to antibiotic modifications and was considered essential in a few cases. Our findings are congruent with a multicenter survey with hypothetical scenarios revealing that PICU physicians commonly obtain EACs as part of “rule out sepsis or infection evaluation” and that the culture data supporting “bacterial pathogenicity” was most important.Reference Willson, Kirby and Kicker6 Longitudinal studies are needed to better understand the clinical value of repeated EACs, particularly among chronically ventilated patients.
This study has several limitations. We primarily surveyed first-call clinicians from a single center with a modest sample size. Variability between clinicians and institutions is likely; therefore, these findings may not be generalizable to other units. However, these findings could be used to develop local assessments. Surveys were conducted as soon as feasible after EACs, but responses may have been subject to recall bias. Lastly, participation in the first survey could have influenced responses in the second survey.
Opportunities may exist to improve EAC utilization. Judicious use of EACs has the potential to reduce antibiotic use and aligns with the national “Choosing Wisely” campaign to reduce medical overuse.Reference Morgan, Croft and Deloney9 Additional studies are needed to clarify the indications and role of EACs in the management of mechanically ventilated patients.
Supplementary material
To view supplementary material for this article, please visit https://doi.org/10.1017/ice.2019.347
Acknowledgments
We thank the staff of the Johns Hopkins Children’s Center Pediatric Intensive Care Unit. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.
Financial support
This work was funded in part by the Johns Hopkins Eudowood Board Baurenschmidt Award, an internal award to A.C.S., and by the National Institutes of Health (grant nos. T32-A1052071 to A.C.S. and K24AI141580 to A.M.).
Conflicts of interest
Authors report no conflicts of interest relevant to this article.
