Bedridden Patient Height Measurement Guide

When are alternative measurements useful?

Standing height may be unavailable when someone cannot stand safely, and a curved spine can make a standing measure unrepresentative. The 2003 BAPEN MUST report describes knee height, ulna length, and demispan as surrogate measurements for adult nutritional screening when height cannot be measured. A surrogate estimate still needs interpretation in the context of the person and the method used.

These instructions concern adults. They do not provide a pediatric growth assessment or an individual medication, nutrition, or procedure decision.

How are the measurements taken?

Knee height: For a person in bed, BAPEN describes lying on the back with the knee and ankle each bent to 90°. Place the lower caliper blade beneath the heel and the upper blade on the front of the thigh above the femoral condyles, about 4 cm above the kneecap; keep the shaft parallel to the lower leg. The report also describes a tape-measure adaptation. This is a heel-to-thigh measurement, not the distance from the floor to the top of the knee. See the BAPEN report, printed pages 98–99.

Ulna length: In the BAPEN booklet, pages 11–12, the arm is bent across the chest and the tape runs from the point of the elbow (olecranon) to the midpoint of the prominent wrist bone (styloid process). Record centimetres to the nearest 0.5 cm for that protocol. An unqualified “forearm length” can use different landmarks and must not be substituted for this ulna measurement in a table.

Demispan: BAPEN measures from the midpoint of the sternal notch to the base of the fingers with the right arm held horizontally and wrist straight. It is not a sternal-notch-to-fingertip distance. The booklet cautions against demispan with obvious spinal curvature and suggests ulna length for bedbound people. See pages 14–15.

Armspan: This is a distinct whole-arm reach measurement. A 1991 study by Kwok and Whitelaw examined armspan in elderly adults; it did not establish a formula for generic forearm length. Do not interchange armspan, demispan, ulna length, and knee height.

What limits a height estimate?

The 1985 Chumlea study developed knee-height equations for people aged 60–90 whose stature could not be measured directly. Its population and error findings cannot be transferred to every bedbound adult or to another body segment. BAPEN also provides different adult tables by age and sex. Measurement conditions, contractures, swelling, and population differences can change how well any chosen method applies.

There is no universal ranking or error margin across these methods. A clinician using a height estimate should select a documented protocol appropriate to the person and note that it is an estimate. When direct measurement becomes possible, record it.

What should be recorded?

Record the body segment, side measured, anatomical endpoints, position, unit, date, and any positioning difficulty. If an equation or BAPEN table is later used, record its source, age group, and the resulting value as estimated height. A measure taken at the fingertip must not be entered into a table expecting the base of the fingers.

Do not average height estimates from different methods merely because they disagree. First check the landmarks, positioning, and whether each method applies to the person. Seek a qualified clinician's assessment when the estimate would affect care.

Frequently asked questions