i-STAT® analysis of intraosseous aspirate

In the absence of vascular access we may resort to sending intraosseous aspirates for analysis, but in some laboratories there is concern that the samples can block autoanalysers.

A study on haematology/oncology patients undergoing diagnostic bone marrow aspiration showed clinically acceptable agreement between venous and intraosseous measurements for pH, base excess, sodium, ionised calcium and glucose using an an i-STAT® point-of-care analyser.

Key points are:

  • The first 1-2 ml should be discarded (as in this study)
  • Lactate hasn’t been assessed
  • These patients weren’t critically ill

Analysis of bloodgas, electrolytes and glucose from intraosseous samples using an i-STAT® point-of-care analyser
Resuscitation. 2014 Mar;85(3):359-63

BACKGROUND: Intraosseous access is used in emergency medicine as an alternative when intravenous access is difficult to obtain. Intraosseous samples can be used for laboratory testing to guide treatment. Many laboratories are reluctant to analyse intraosseous samples, as they frequently block conventional laboratory equipment. We aimed to evaluate the feasibility and accuracy of analysis of intraosseous samples using an i-STAT(®) point-of-care analyser.

METHODS: Intravenous and intraosseous samples of twenty children presenting for scheduled diagnostic bone marrow aspiration were analysed using an i-STAT(®) point-of-care analyser. Sample types were compared using Bland Altman plots and by calculating intraclass correlation coefficients and coefficients of variance.

RESULTS: The handheld i-STAT(®)point-of-care analyser proved suitable for analysing intraosseous samples without technical difficulties. Differences between venous and intraosseous samples were clinically acceptable for pH, base excess, sodium, ionised calcium and glucose in these haemodynamically stable patients. The intraclass correlation coefficient was excellent (>0.8) for comparison of intraosseous and intravenous base excess, and moderate (around 0.6) for bicarbonate, sodium and glucose. The coefficient of variance of intraosseous samples was smaller than that of venous samples for most variables.

CONCLUSION: Analysis of intraosseous samples with a bedside, single-use cartridge-based analyser is feasible and avoids the problem of bone marrow contents damaging conventional laboratory equipment. In an emergency situation point-of-care analysis of intraosseous aspirates may be a useful guide to treatment.