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Agreement between capillary and venous lactate in emergency department patients: prospective observational study
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  • Published on:
    Response to: Methodological bias in comparison of lactate values between Handheld analyser and Blood gas analyser
    • Kevin Hung, Accident and Emergency Medicine Chinese University of Hong Kong and Prince of Wales Hospital, Shatin, Hong Kong

    Dear Editor,

    Léguillier commented on the methodological biases in our recent study. We thank Léguillier for his interest and here we provide further clarification of the points mentioned in his letter.

    Firstly we would like to clarify that the two handheld analysers used: Nova StatStrip Xpress Lactate Meter (Nova Biomedical, Waltham, USA) and Lactate Scout+ (EKF Diagnostics, Leipzig, Germany), were both calibrated, maintained and tested for quality control by their respective companies. In the absence of prior evidence of the superiority of one make of machine over another, we chose to compare two standard models.

    Regarding the comment on the sample size, the calculated sample size using Bland-Altman method[1,2] was directed at the primary outcome measure, which was the agreement of the capillary blood lactate level measured by handheld lactate analyser when compared with the reference standard technique. Due to the diverse spectrum of patients seen in the ED, the range of lactate levels was representative of our daily clinical practice and was thus pragmatic. Furthermore, our sample size of 240 was larger than previous studies [3-7] ranging from 24 to 120 patients.

    Lastly, we chose to use a cut off of 2 mmol/L as this is the upper limit of a normal lactate value. As we mentioned in the paper, screening ED venous lactate levels using a handheld analyser could provide information to shorten the time to identify patients at risk and to allow rap...

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    Conflict of Interest:
    None declared.
  • Published on:
    Methodological bias in comparison of lactate values between Handheld analyser and Blood gas analyser
    • Teddy Léguillier, Clinical Pharmacist, PhD, PharmD Necker Enfants malades Hospital
    • Other Contributors:
      • Romain Jouffroy, Critical Care Practitioner, MD
      • Carole Hennequin, Clinical Pharmacist, PhD, PharmD
      • Jean-Louis Beaudeux, Clinical Pharmacist, PhD, PharmD
      • Valérie Nivet-Antoine, Clinical Pharmacist, PhD, PharmD

    Dear Editor,

    In a recent issue, Graham et al [1] compared the transferability for blood lactate measurement between two assays. These authors raised two conclusions. First, a poor agreement between blood capillary and venous lactate measurements was reported; second, the use of blood capillary lactate measurement for diagnosis purposes was discouraged. From our point of view, this paper presents some methodological bias which do not allow the authors to draw those conclusions. We would like to advance three important considerations to support this claim.

    Firstly, in the same way that laboratory analysers, handheld analysers must be tested for their analytical performances and submitted to periodic quality control check to ensure proper functioning of the equipment, accuracy of measurement and consistent readings. In the report [1], neither analytical performance nor quality control have been mentioned for the handheld analysers.

    Secondly, to confirm a correct agreement between the measurements provided by different devices, the number of patients enrolled appears quite low. Indeed, the devices measurement range must be taken into account [3]. Lactate values ranged from 0.7 to 5.38 mmol.l-1 , and 62.8% of the patients had lactate values < 2 mmol.l-1 while the devices had a measurement lactate range from 0.5 to 25 mmol.l-1. By this way, authors draw their conclusion only with the lower end of the range without considering high blood lactate values. We...

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    Conflict of Interest:
    None declared.