Assessing Water-Electrolyte Changes of Hyperglycaemic Hyperosmolar Coma

Abstract

Aim: We reported new methods to accurately estimate salt and water deficits during hyperglycaemic hyperosmolar coma (HC), valid under restricted boundary conditions. The accuracy of these estimates is herein verified over the unrestricted spectrum of abnormalities, to correctly evaluate any patient with just one algorithm that recognizes the boundary conditions pertaining to each abnormality, choosing the appropriate calculations.

Methods: A large number of cases of HC was simulated on computer by subtracting an exhaustive combination of water, sodium and chloride losses coupled to a large variety of gains in glucose. Altered solute concentrations were generated. From these true plasma concentrations generated by the computer, the losses of water and electrolytes were back-calculated with our new computational algorithm, by knowing in addition only the normal total body water and extra-cellular volume. The accuracy of the method was tested by comparing true to calculated values over the entire range of deranged values. In 100 patients admitted to hospital for HC these same computations were performed, where calculated data were validated by comparing them to true data obtained by balance studies performed during correction of the abnormality.

Results: Both in simulated and real cases of HC true and calculated data for the changes in Na and volume were significantly correlated (R²=0.76 and 0.50, respectively, P<0.01), while their mean values were not significantly different by paired “t” tests (P>0.05 for all).

Conclusion: Our new computation algorithm, applicable to the bed-side, useful in accurately assessing the average water-electrolyte deficits of HC, can be used to guide correct re-infusion strategies.

Key words

plasma osmolality - hyperosmolar coma - sodium deficit - water loss - body fluids

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1 Footnote: SIAE registration 8/16/06, number 0604311.

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