Application of multivariate autoregressive modelling for analysing chloride/potassium/bicarbonate relationship in the body.

The authors repeatedly analysed course data of acid-base disturbances accompanying hypochloraemia and/or hypokalaemia by means of multivariate autoregressive modelling. It was found that the regulatory relationship between chloride and bicarbonate is inverse between the following two hypochloraemic hyperbicarbonataemic states: the one induced by chloride depletion and the other induced by CO2 retention. Also, the study revealed an independent role of potassium deficiency in the development of metabolic alkalosis, especially in cases with mineralocorticoid-induced alkalosis. The present approach enabled the authors to solve a long-standing problem, i.e. to differentiate between the roles of chloride and potassium in the development of metabolic alkalosis.