Question 16

Outline the methods available to estimate fluid balance in the critically ill patient  and briefly discuss their advantages  and limitations. (You may tabulate your answer)

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College Answer




Clinical – oedema, JVP,
skin turgor, hydration of tongue

Simple, easily done by the
bedside, not time consuming

Lack specificity

Intake–output chart

Simple method, reasonably
accurate in most patients

Labour intensive,
Insensible water losses not factored in, Losses through leaks in bed, drain disconnections and in the case of burns patients, severe evaporative water losses not taken into account


May be useful in
uncomplicated critically ill patients

Not routinely used in all
ICUs, time consuming, labour intensive, difficult in the ventilated patient, (zeroing has to be done properly with sheets and pillows), addition of moisture from perspiration
and spills can change baseline weight
Correlation with I-O charts not high.


Used to predict
intravascular status

Significant limitations


Shown to be of value in a
trial comparing it with PAC

Invasive technique

Research methods include
Bioelectrical impedance, determination of total body water and plasma volume using radionuclide techniques

Research tools, do not lend
themselves to serial measurements


This question is identical to Question 16 from the second paper of 2009.