The use of chloride–sodium ratio in the evaluation of metabolic acidosis in critically ill neonates

Abstract

Acid-base disturbances have been usually evaluated with the traditional Henderson-Hasselbach method and Stewart's physiochemical approach by quantifying anions of tissue acids (TA). It is hypothesized that an increase in tissue acids during metabolic acidosis would cause a compensatory decrease in the plasma chloride (Cl) relative to sodium (Cl-Na ratio) in order to preserve electroneutral balance. Therefore, we aimed to investigate the use of Cl-Na ratio as a bedside tool to evaluate the identifying raised TA in neonates as an alternative to complex calculations of Stewart's physiochemical approach. This retrospective study was conducted between January 2008 and December 2009. Infants were included in the study when blood gas analysis reveals a metabolic acidosis; pH <7.25 and sHCO(3) concentration was <22 mEq/L. The Cl-Na ratio, sodium-chloride difference (Diff(NaCl)), anion gap (AG), albumin-corrected AG (AG(corr)), strong ion difference (SID), unmeasured anions (UMA), and TA were calculated at each episode of metabolic acidosis. A total of 105 metabolic acidosis episodes occurred in 59 infants during follow-up. Hypochloremic metabolic acidosis occurred in 17 (16%) of samples, and all had increased TA. The dominant component of TA was UMA rather than lactate. There was a negative correlation between the Cl-Na ratio and SID, AG(corr), UMA, and TA. Also, there was a positive correlation between Diff(NaCl) and SID, AG(corr), UMA, and TA. Base deficit and actual bicarbonate performed poorly in identifying the TA. In conclusion, our study suggested that Diff(NaCl) and Cl-Na ratio are simple and fast, and may be an alternative method to complex Stewart's physiochemical approach in identifying raised UMA and TA in critically ill neonates.

The effects of the chloride:sodium ratio on acid-base statusand mortality in septic patients

“…We think that this notion is most important in septic patients who have increased mortality. Rare combinations can be seen in daily clinical practice, and those combinations were also discussed in previous studies (Table 3) (6,9,13,(15)(16)(17)(18)(19). Kurt et al (15) indicated the presence of hypochloremic metabolic acidosis in 16% of acid-base disorders.…”

Biochemistry in Intensive Care

“…This leads to a decrease in the chloride:sodium ratio, an increase in the SID, and thus a decrease in water dissociation and a fall in hydrogen ion activity (hypochloraemic alkalosis). Thus assessment of chloride, and in particular the chloride:sodium ratio, becomes of real value in determining the acid-base disturbance and assessing treatment in critically ill patients [33][34][35][36][37]. Assessment of SID can be used as a quantitative guideline for chloride (NaCl or KCl) replacement.…”

Les utilisations du trou anionique plasmatique corrigé pour le diagnostic de l’acidose métabolique

“…Le rapport Cl/Na, et, dans une moindre mesure, la différence [Na + ] -[Cl -] permettent d'évaluer la présence d'acides tissulaires, c'est-à-dire lactate et anions indosés, et constituent donc un substitut relativement fiable au TAPc, un rapport Cl/Na inférieur à 0,75 étant en faveur d'une augmentation d'acides tissulaires et un rapport supé-rieur à 0,79 excluant cette présence [45]. Enfin, il a été montré que le rapport Cl/Na a une bonne corrélation inverse avec le TAPc (r = -0,806), tandis que la différence [Na + ] -[Cl -] a une bonne corrélation « positive » avec le TAPc (r = 0,82) dans une population néonatale [46].…”