Bicarbonate Variation Monitoring With Indirect Calorimetry

Condition(s) studied

Investigational drug(s) / intervention(s)

Indirect calorimetry measurement: Setup of an indirect calorimetry monitor

Study summary

Patients admitted to the intensive care unit frequently exhibit abnormal blood bicarbonate levels. These abnormalities are associated with patient outcomes and often prompt clinicians to modify management, either diagnostically or therapeutically (e.g., initiation or adjustment of mechanical ventilation, initiation or modification of extracorporeal renal replacement therapy, administration of specific diuretics, or sodium bicarbonate infusion).

Currently, the only way to determine blood bicarbonate concentration is through repeated blood sampling for laboratory analysis. However, this method is both discontinuous and invasive.

We have generated an in silico hypothesis suggesting that the mismatch between cellular CO₂ production/elimination and pulmonary CO₂ elimination reflects changes in blood bicarbonate levels. We propose to test this hypothesis in a cohort of intensive care unit patients.

If confirmed, indirect calorimetry could be positioned as a continuous, non-invasive monitoring tool for blood bicarbonate.

Eligibility

Primary outcome measure(s)

• Correlation coefficient between the CO₂ production/elimination mismatch assessed by indirect calorimetry and the change in blood bicarbonate over the study period. — At day 1
  CO₂ production/elimination mismatch is estimated using the indirect calorimetry, assuming that the respiratory quotient remains constant throughout the study. Change in blood bicarbonate is obtained using two consecutive arterial blood samples. This relationship will be assessed using Pearson's correlation coefficient if assumptions are met (normality and linearity); otherwise, Spearman's coefficient will be used. The correlation coefficient will be reported with its 95% confidence interval and p-value, and the relationship will be illustrated with a scatter plot and regression line or trend curve.

Trial sites (1)

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