Anesthesiology, Article

Metabolic acidosis in septic shock: is the Stewart theory the magic bullet?

clinical practice [4], the used parameters should have a clinical relevant reproducibility to avoid center-dependent patient treatment.

Gildas Gueret Pole anesthesie Reanimation CHU Brest, F-29200 France

E-mail address: [email protected]

Ba-Vinh Nguyen Service d’anesthesie reanimation HIA Brest, F-29200 France

Damien Lozachmeur Pole anesthesie Reanimation CHU Brest, F-29200 France

Ahmed Khalifa

Service de chirurgie cardiaque, thoracique et vasculaire

CHU Brest, F-29200 France

Jean-Luc Carre

Service de biochimie et biologie moleculaire

CHU Brest, F-29200 France

Mehdi Ould-Ahmed Service d’anesthesie reanimation HIA Brest, F-29200 France

Charles C. Arvieux Pole anesthesie Reanimation CHU Brest, F-29200 France

doi:10.1016/j.ajem.2011.03.029

References

  1. Mallat J, Michel D, Salaun P, Thevenin D, Tronchon L. Defining metabolic acidosis in patients with septic shock using Stewart approach. Am J Emerg Med 2011 (Epub ahead of print).
  2. Gueret G, Guennegan C, Nguyen BV, Arvieux CC, Carre JL. Can we really use the Stewart-Fencl method to analyze acid-base derangements in clinical practice? J Crit Care 2011;26(1):96-7.

0735-6757/$ – see front matter (C) 2011

image of Fig. 1692 Correspondence

Fig. 1 Relation between 2 analyzers for chloride and corrected chloride according to Bland and Altman presentation.

  1. Nguyen BV, Vincent JL, Hamm JB, Abalain JH, Carre JL, Nowak E, et al. The reproducibility of Stewart parameters for acid-base diagnosis using two central laboratory analyzers. Anesth Analg 2009;109(5):1517-23.
  2. Srisawat N, Gunnerson KJ, Kellum JA. Can we really use the Stewart- Fenc method to analyze acid-base derangement in clinical practice?– Author response. J Crit Care 2011;26(1):97-8.

“Metabolic acidosis in septic shock: is the Stewart theory the magic bullet?” Response to the authors

To the Editor,

We read with interest the letter “Metabolic acidosis in septic shock: is the Stewart theory the magic bullet?” and we thank the authors for their thoughtful comments about our study “Defining metabolic acidosis in patients with septic shock using Stewart approach” [1]. The author’s main concern seems to be the reproducibility of biologic measurements between different analyzers. However, we would like to point out that, in our study, all samples, for both patients and volunteers, were analyzed using the same analyzers.

We certainly agree that, although variation of each individual assay is very small, the variation of strong ion gap is influenced by the individual variations of all 9 components. However, this statement not only applies to SIG, but is also true for other calculated variables like standard base excess (SBE) and anion gap . Moreover, in the same study [2] where the authors demonstrated the poor reproducibility of SIG between 2 analyzers, we can see that, even if the AG depends on fewer parameters, its reproducibility was also weak. Thus, we are wondering

which method did the authors use to detect the presence of unmeasured anions in their clinical practice? Nevertheless, we agree that a great variability between different analyzers is a major limitation when comparing studies regarding acid- base disorders. For that reason and as we have already mentioned in our discussion [1], it is important for any hospital reporting SIG and AG values to establish local confidence intervals, incorporating measurement and popu- lation variability. Otherwise, results can be misinterpreted and diagnostic conclusions skewed.

Finally, the authors also questioned the comparability between the groups of nonacidosis SBE/elevated SIG and acidosis SBE/elevated SIG. We would like to reassure them that the clinical characteristics and the Sequential Organ Failure Assessment score were not different between these groups.

Jihad Mallat MD Service de Reanimation polyvalente, Centre hospitalier Dr Shaffner de Lens, 62307 Lens Cedex, France

E-mail address: [email protected] doi:10.1016/j.ajem.2011.03.028

References

  1. Mallat J, Michel D, Salaun P, Thevenin D, Tronchon L. Defining metabolic acidosis in patients with septic shock using Stewart approach. Am J Emerg Med 2011 (Epub ahead of print).
  2. Nguyen BV, Vincent JL, Hamm JB, Abalain JH, Carre JL, Nowak E, et al. The reproducibility of Stewart parameters for acid-base diagnosis using two central laboratory analyzers. Anesth Analg 2009;109(5): 1517-23.

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