open access

Vol 45, No 2 (2013 Apr-Jun)
Review articles
Submitted: 2013-07-05
Accepted: 2013-07-05
Get Citation

Theorethical principles of fluid managment according to physicochemical Stewart approach

Piotr Smuszkiewicz, Jakub Szrama
DOI: 10.5603/AIT.2013.0022
·
Anaesthesiol Intensive Ther 2013;45(2):99-105.

open access

Vol 45, No 2 (2013 Apr-Jun)
Review articles
Submitted: 2013-07-05
Accepted: 2013-07-05

Abstract

Interpreting acid base disturbances according to the physicochemical Stewart approach allows the cause of such abnormalities to be discovered. This method is based on three independent variables: SID (strong ion difference), mainly sodium and chloride; weak acids concentration — Atot, mainly albumins and phosphate; and carbon dioxide tension — pCO2. These three independent variables are responsible for the change of water dissociation and for the change in H+ concentration and, consequently, the change in serum pH value. The SID value of the fluids administered to a patient is responsible for the change of serum SID value and therefore causes a change in the patient’s acid base status. During the infusion of a given fluid, the SID value of the serum becomes closer to the SID value of that fluid; on the other hand, the infusion causes a decrease in Atot concentration. In order to avoid acid base disturbances connected with fluid administration, the SID value of fluids being administered should be greater than 0 and lower then the serum SID. It has been suggested that fluids should be given of which the SID value is as close as possible to the actual serum HCO3 concentration. Knowing the SID value of the fluid administered, and the serum HCO3 concentration, one can expect a change of serum pH after a fluid infusion. Administering a fluid with a SID greater than the HCO3 concentration causes a pH increase towards alkalosis. Likewise, administering a a fluid with a SID lower than the HCO3 concentration causes a pH decrease towards acidosis. It seems that knowledge of the electrolyte concentration and the SID value of an administered fluid is an important factor regarding acid base disturbances.

Abstract

Interpreting acid base disturbances according to the physicochemical Stewart approach allows the cause of such abnormalities to be discovered. This method is based on three independent variables: SID (strong ion difference), mainly sodium and chloride; weak acids concentration — Atot, mainly albumins and phosphate; and carbon dioxide tension — pCO2. These three independent variables are responsible for the change of water dissociation and for the change in H+ concentration and, consequently, the change in serum pH value. The SID value of the fluids administered to a patient is responsible for the change of serum SID value and therefore causes a change in the patient’s acid base status. During the infusion of a given fluid, the SID value of the serum becomes closer to the SID value of that fluid; on the other hand, the infusion causes a decrease in Atot concentration. In order to avoid acid base disturbances connected with fluid administration, the SID value of fluids being administered should be greater than 0 and lower then the serum SID. It has been suggested that fluids should be given of which the SID value is as close as possible to the actual serum HCO3 concentration. Knowing the SID value of the fluid administered, and the serum HCO3 concentration, one can expect a change of serum pH after a fluid infusion. Administering a fluid with a SID greater than the HCO3 concentration causes a pH increase towards alkalosis. Likewise, administering a a fluid with a SID lower than the HCO3 concentration causes a pH decrease towards acidosis. It seems that knowledge of the electrolyte concentration and the SID value of an administered fluid is an important factor regarding acid base disturbances.

Get Citation

Keywords

fluid management, acid base status, Stewart approach

About this article
Title

Theorethical principles of fluid managment according to physicochemical Stewart approach

Journal

Anaesthesiology Intensive Therapy

Issue

Vol 45, No 2 (2013 Apr-Jun)

Pages

99-105

DOI

10.5603/AIT.2013.0022

Bibliographic record

Anaesthesiol Intensive Ther 2013;45(2):99-105.

Keywords

fluid management
acid base status
Stewart approach

Authors

Piotr Smuszkiewicz
Jakub Szrama

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

VM Media sp. z o.o. VM Group sp.k., Grupa Via Medica, Świętokrzyska 73 St., 80–180 Gdańsk

tel.:+48 58 320 94 94, faks:+48 58 320 94 60, e-mail: viamedica@viamedica.pl