Research
Blood Culture Accuracy: Discards From Central Venous Catheters in Pediatric Oncology Patients in the Emergency Department

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Abstract

Introduction

Lack of specific guidelines regarding collection of blood for culture from central venous catheters (CVCs) has led to inconsistencies in policies among hospitals. Currently, no specific professional or regulatory recommendations exist in relation to using, reinfusing, or discarding blood drawn from CVCs before drawing blood for a culture. Repeated wasting of blood may harm immunocompromised pediatric oncology patients. The purpose of this comparative study was to determine whether differences exist between blood cultures obtained from the first 5 mL of blood drawn from a CVC line when compared with the second 5 mL drawn.

Methods

During 2009-2011, 62 pediatric oncology patients with CVCs and orders for blood cultures to determine potential sepsis were enrolled during ED visits. Trained study nurses aseptically drew blood and injected the normally discarded first 5 mL and the second specimen (usual care) into separate culture bottles. Specimens were processed in the microbiology laboratory per hospital policy.

Results

Positive cultures were evaluated to assess agreement between specimen results and to determine that the identified pathogen was not a contaminant. Out of 186 blood culture pairs, 4.8% demonstrated positive results. In all positive-positive matches, the normal discard specimen contained the same organism as the usual care specimen. In 4 matches, the normally discarded specimen demonstrated notably earlier time to positivity (4 to 31 hours) compared with the usual care specimen, which resulted in earlier initiation of definitive antibiotics.

Discussion

These findings support the accuracy of the specimen that is normally discarded and suggest the need to reconsider its use for blood culture testing.

Section snippets

Background and Literature Review

Current practice guidelines do not include recommendations about whether to discard, use, or reinfuse blood drawn prior to obtaining blood for cultures.1., 2., 3. In fact, policies and practices vary regarding CVC line insertion, access, and maintenance for both children and adults.4., 5., 6., 7., 8. Penwarden and Montgomery5 developed a protocol for blood cultures in patients with CVCs based on the little available evidence and expert opinion. This protocol requires a peripheral blood draw

Preliminary Investigation

Subsequent to a literature review using Medline to determine whether a national standard of care existed for blood withdrawal from CVCs for cultures, telephone calls were made to emergency personnel in major pediatric and oncology medical centers in the United States. Concurrently, an E-mail request was sent to a list of pediatric emergency managers. Responses showed divergent policies: most hospitals discard 3 to 5 mL before drawing blood for a blood culture specimen; some hospitals changed

Significance

Given significant variability among emergency departments regarding whether the first withdrawn CVC specimen for blood cultures is used, evidence is needed to establish practice recommendations.

Research Questions

The following research questions were formulated to address these issues and relate to blood drawn from CVCs in pediatric oncology patients for whom blood cultures were ordered upon admission to the emergency department:

  • 1.

    What are the sensitivity and specificity of specimen No. 1 (the normal 5 mL discard), using specimen No. 2 (usual care; 5 mL blood sent to laboratory for blood culture) as the “gold standard”?

  • 2.

    What are the PPV and negative predictive value (NPV) of specimen No. 1?

  • 3.

    How often does

Study Setting And Sample

Our 488-bed institution is a Magnet-accredited community hospital located in Orange County, California. At the time of the study, the emergency department provided services for our hospital and the adjacent children’s hospital.

All pediatric oncology patients who potentially had sepsis and presented to the emergency department with a CVC and an order for blood cultures from the CVC were considered as possible study participants. Excluded were patients with peripherally inserted central catheters

Results

Numbers of culture pairs per patient varied based on the number of CVCs and the number of lumens per CVC. Each culture pair consisted of two blood specimens per aerobic or anaerobic plating. Microbiology reported positive findings from either specimen on one culture report. Between September 2009 and August 2011, samples from 62 pediatric patients were studied with 186 aerobic and anaerobic culture pairs (potential agreement/disagreements). Sixty-one patients had either Port-a-Cath or Broviac

Discussion

This study is the first to document that initial blood specimens drawn from pediatric oncology patients’ CVCs have high sensitivity and specificity in relation to a subsequent CVC blood draw. This study demonstrated a 4.8% positive rate for blood cultures (aerobic and anaerobic) drawn from CVCs. The specificity of the normally discarded specimens was high compared with the routinely used specimen (specimen No. 2), whereas the sensitivity was slightly lower. These findings are consistent with

Limitations and Implications for Emergency Nurses

The major limitation of our study was our inability to use peripheral blood draws as a gold standard for validating accuracy of the discarded specimen. Additionally, this study was small, with potentially septic pediatric hematology patients in one southern California county, which limits generalizability. Central lines included Port-a-Cath and Broviac catheters; results would not be generalizable to other types of catheters. However, the paucity of research in this area not only supports a

Acknowledgments

We thank the nurse data collectors for this study: Sara Asmine, Rachel Crook, E’lyn Houghton, Kent Lee, Katie Marino, Christine Marshall, Larisa K. Taraborrelli, Julia Walker, and Amber Willson.

Elizabeth J. Winokur, Member, Orange Coast Chapter, is Clinical Educator, Emergency Department & Behavioral Health Services, St. Joseph Hospital, Orange, CA.

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  • Cited by (0)

    Elizabeth J. Winokur, Member, Orange Coast Chapter, is Clinical Educator, Emergency Department & Behavioral Health Services, St. Joseph Hospital, Orange, CA.

    Debra Pai, Member, Orange Coast Chapter, is Clinical Nurse III, St. Joseph Hospital, Orange, CA.

    Dana N. Rutledge is Professor, California State University, Fullerton, CA.

    Kate Vogel is Supervisor, Microbiology and Immunology, St. Joseph Hospital, Orange, CA.

    Sadeeka Al-Majid is Associate Professor, California State University, Fullerton, CA.

    Christine Marshall, Member, Orange Coast Chapter, is Clinical Nurse IV, St. Joseph Hospital, Orange, CA.

    Paul Sheikewitz is ED Physician, St. Joseph Hospital, Orange, CA.

    Earn Up to 9.0 CE Hours. See page 410.

    Partially funded by American Nurses Foundation Grant ID #2010-046 and St. Joseph Hospital Foundation.

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