BMI Flashcards
What is the definition of BMI?
Body mass index- measurement derived from patients height and weight (used to assess whether patients weight is within normal range).
What are the units for BMI?
kg/m2
When can BMI not be used?
As it measures just height and weight, can’t be used for bodybuilders for example as doesn’t include context so would show them as being severely overweight.
What are the BMI categories?
-<18.5- underweight
-18.5-24.9- healthy weight
-25-29.9- overweight
-30-39.9- obese
-40 or above- severely obese
Why do we need to know BMI?
Used to estimate body fat, determine overall fitness and risk of developing chronic disease, change in BMI can show deterioration or improvement in condition.
What are the implications of not being in the normal weight range?
They are more prone to disease (overweight more prone to diabetes and sleep apnoea) and resp patients with low BMI have poorer prognosis.
Why use the standing height?
This is preferred method of measurement, important to measure accurately, use patients current height, unable to stand (use alternative methods).
What does the patient need to remove for height measurement?
Outer clothing, shoes, hair clips, plaits or braids, orthopaedic braces.
How should the patient be positioned for a height measurement?
Feet together, feet flat on the ground, heels touching the back of the plate, legs straight, buttocks and scapula against the wall, arms loosely at side.
How should the head be positioned for a height measurement?
Corner of the eyes horizontal to the middle of the ear.
What are the 3 alternative methods to measure height if the patient is unable to stand unsupported?
-Full arm span
-Demi arm span
-Ulna length
How do you perform an arm span measurement?
Measure finger tip to finger tip, mark on the wall and measure the distance between.
Estimate the standing height:
Males arm span/ 1.03
Females arm span/ 1.01
What is a limitation of the arm span measurement?
Some people wouldn’t be able to stretch their arms out as required.
How do you perform a Demi arm span measurement?
Arm outstretched, palm forwards, from the base of middle finger to sternal notch using tape measure.
Females: Height= (1.35x demi span)+60.1
Males: Height= (1.4x demi span) +57.8
How do you perform an ulna length measurement?
Arm bent across the chest (left side), palm flat across chest and fingers pointing to the opposite shoulder. Length from point of elbow to midpoint of prominent bone on wrist measured. A chart is then used to convert to height.
