Hydration (water balance) is vital for the survival of all mammalian species. In many intensive care units and hospital wards around the world, water loss is measured by nursing staff collecting a patient’s urine in a bag and either measuring the volume collected or weighing the bag to calculate the volume indirectly. Additional water loss (gastro-intestinal, skin, respiratory, and metabolic) is either approximated or ignored as an irrelevant or inconsequential process.
Assessment for water loss is undertaken every hour. A calculator is then used to determine the amount of loss and the requirement for replacement. If clinically indicated, water is then replaced using an intravenous infusion of sterile water and ionic concentrate. The calculations for water loss and replacement are only estimates, and combined with the potential for errors in documentation and calculation, can lead to over or under treatment and negative outcomes including mortality.
Importantly, the current process of monitoring hydration does not consider the water loss and urine ionic concentration in real-time. This is significant, as the required level of hydration in mammalian species is determined by a balance of water and ions. Increasing or decreasing a patient’s water intake without considering the balance of sodium and potassium may result in sub-optimal outcomes for the patient. Water balance is important in order to avoid hyponatremia (low blood sodium ion concentration resulting from too much water or reduced sodium intake unmatched with increased sodium loss) and hypernatremia (high blood sodium ion concentration resulting from insufficient water intake or rarely, excess sodium retention due to disease).
Incorrect estimates of water balance may lead to clinical complications, increased length of hospital stay and mortality.
There are currently no devices on the market that facilitate real-time measurement of water loss and ionic concentration in urine. It is therefore necessary for critical care nurses and medical staff to measure parameters such as urine sodium concentration and plasma sodium concentration with an in-vitro analyzer, a time consuming and manual task. In smaller hospitals it is often necessary for samples to be sent to an external laboratory for analysis, further delaying clinical decisions and potentially impacting patient outcomes.