Agreement of IntraOsseous aspirate and Peripheral Blood samples for predetermined haematological and biochemical tests on automated laboratory analysers and point-of- care devices: a prospective observational study (IOPB study)

Abstract

Introduction: In the resuscitation and critical illness settings, when timely peripheral or central venous access is not obtained, the intraosseous (IO) route allows indirect access to the venous circulation. The IOPB study examined the agreement of iliac crest and proximal tibia IO aspirate to paired peripheral venous blood (PVB) for measurement of various parameters on automated laboratory analysers (ALA) and point-ofcare (POC) devices. Method: A single centre prospective observational study was performed. Near-simultaneous IO aspirate from the iliac crest and proximal tibia, along with paired PVB samples, were collected from haemodynamically stable participants. ALA used were Sysmex® XN-9000, Stago STA-R MAX® and STA-R Evolution®, and Cobas® 8000 and 6000. POC devices used were HemoCue® and ABL90 blood gas devices. Agreement was assessed through the Bland-Altman limits of agreement method (LoA). Measurement differences were compared against clinically acceptable difference (CAD) criteria adopted from RCPAQAP analytical performance specifications (APS). Given the limitations of using RCPAQAP APS with IO aspirate specimens, agreement was also assessed through the clinical judgement of the authors. Results: 180 individuals (age range 21-87 years) provided samples. 140 had haematological indications for a bone marrow biopsy, with the remaining 40 being healthy volunteers. All had PVB and iliac crest IO aspirate collected, while 65 also had proximal tibia IO aspirate obtained. Excluding specimens with macroscopic clots, an analyser result was provided in ≥97% of instances for most parameters. When using RCPAQAP APS, strict agreement was apparent for MCV and haematocrit; however, many parameters had their mean differences within these CAD criteria and were ultimately deemed to have adequate agreement based on clinical judgement. The measurement differences of certain parameters such as potassium, platelet count, leukocyte count and differentials were deemed excessive. Conclusion: The IOPB study confirmed the feasibility of analysing IO aspirate on ALA and POC devices. Many of the parameters analysed in this study were deemed to have adequate agreement for use in the resuscitation setting. Because agreement based on clinical judgement is subjective, clinicians requesting laboratory testing of IO aspirate specimens must appreciate the degree of measurement inaccuracy compared to PVB.