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Maintenance Fluid Therapy in Children

The Need for Water

Alok Kalia, MD

We drink water, or a water-containing beverage, five to ten times a day. We do not have to keep track of our fluid intake.

The thirst-creating mechanism is exquisitely sensitive to an increase in plasma osmolality and as long as there is free access to water, intake will never be less than the need.

So, we rely on thirst to guide water intake. But what about a person who is receiving only intravenous fluids or gavage feeding? In this individual, the thirst mechanism has been bypassed. You, the prescribing physician, must decide how much fluid to administer.

So how much water does a person need in a day? To answer this question, we must ask another.


Why do we drink water?

Why do we drink water?

Correct. It is loss of water from the body that tends to reduce plasma volume and increased plasma osmolality. We drink water to replace the water that is lost from the body.Incorrect. Select another answer.Your answer has been saved.
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So, the only absolute reason to drink water is to replace losses. The need for water over any period of time is equal to the loss of water over that period of time. Conventionally, water requirement is calculated in daily, or 24-hour, increments.

To be able to calculate daily water requirement, we need to be able to estimate daily water loss in individuals of different ages. For this, we need to know the routes of water loss and be familiar with the physiologic and pathological determinants of the rate of loss from each route.