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

Method	Advantages	Limitations
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
Body-weight	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.


CVP and PCWP	Used to predict intravascular status	Significant limitations
EVLW	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

Discussion

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

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