Demispan

Demispan is a measurement of a patient's size, being half the distance between their hands outstretched to either side. It can be used to estimate their height in situations where it is hard to measure someone's height directly, e.g. if they are unable to stand.

Measurement
It is measured from a point on the midline at their suprasternal notch to the base of their middle and ring fingers along either horizontally outstretched arm and with their wrist in neutral rotation and zero extension or flexion.

Measurement of the demispan is an alternative to patient standing height when measuring patient skeletal frame size for the purposes of nutritional or other growth assessment. It can be undertaken while the patient remains seated and thus is especially useful if they are unable to stand. It is also a more accurate measure of skeletal frame size in the elderly where standing height may be shortened by kyphosis and/or vertebral collapse.

Demispan should be measured with a stainless steel (non-stretchable) tape.

An estimate of patient height can be computed from their demispan measurement:

Female height in cm = (1.35 x demispan in cm) + 60.1

Male height in cm = (1.40 x demispan in cm) + 57.8

This in turn allows computation of an estimated Body Mass Index (BMI) using the normal algorithm. Alternatively, instead of a BMI, a Demiquet Index can be computed directly from the demispan:

Demiquet = weight (in kg) divided by the square of the demispan (in cm)

The demiquet index is a more reliable measure of nutritional status than a BMI estimation in the elderly, for the reasons given above.