Skip to main content

Contribution of red blood cells to the compensation for hypocapnic alkalosis through plasmatic strong ion difference variations

Introduction

Chloride shift is the movement of chloride between red blood cells (RBC) and plasma (and vice versa) caused by variations in pCO2. The aim of our study was to investigate changes in plasmatic strong ion difference (SID) during acute variations in pCO2 and their possible role in the compensation for hypocapnic alkalosis.

Methods

Patients admitted in this year to our ICU requiring extra-corporeal CO2 removal were enrolled. Couples of measurements of gases and electrolytes on blood entering (v) and leaving (a) the respiratory membrane were analyzed. SID was calculated as [Na+] + [K+] + 2[Ca2+] - [Cl-] - [Lac-]. Percentage variations in SID (SID%) were calculated as (SIDv - SIDa) × 100/SIDv. The same calculation was performed for pCO2 (pCO2%). Comparison between v and a values was performed by paired t test or the signed-rank test, as appropriate.

Results

Analysis was conducted on 205 sample-couples of six enrolled patients. A significant difference (P < 0.001) between mean values of v-a samples was observed for pH (7.41 ± 0.05 vs. 7.51 ± 0.06), pCO2 (48 ± 6 vs. 35 ± 7 mmHg), [Na+] (136.3 ± 4.0 vs. 135.2 ± 4.0 mEq/l), [Cl-] (101.5 ± 5.3 vs. 102.8 ± 5.2 mEq/l) and therefore SID (39.5 ± 4.0 vs. 36.9 ± 4.1 mEq/l). pCO2% and SID% significantly correlated (r2 = 0.28, P < 0.001). Graphical representation by quartiles of pCO2% is shown in Figure 1.

Figure 1
figure1

* P < 0.05 versus first quartile. §P < 0.05 versus second. #P < 0.05 versus third. One-way ANOVA.

Conclusions

As a reduction in SID decreases pH, the observed movement of anions and cations probably limited the alkalinization caused by hypocapnia. In this model, the only source of electrolytes are blood cells (that is, no interstitium and no influence of the kidney is present); it is therefore conceivable to consider the observed phenomenon as the contribution of RBC for the compensation of acute hypocapnic alkalosis.

Author information

Affiliations

Authors

Corresponding author

Correspondence to T Langer.

Rights and permissions

This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and Permissions

About this article

Cite this article

Langer, T., Zani, L., Carlesso, E. et al. Contribution of red blood cells to the compensation for hypocapnic alkalosis through plasmatic strong ion difference variations. Crit Care 15, P134 (2011). https://doi.org/10.1186/cc9554

Download citation

Keywords

  • Public Health
  • Chloride
  • Blood Cell
  • Graphical Representation
  • Emergency Medicine