Localise the Failing Motor Unit — and Trend the Breath

Five questions, one localisationPick what your hands and your penlight actually found. The bench scores the profile against all five levels of the motor unit and shows you which one it fits — and where the profile is internally inconsistent.

Or load a bedside picture

The vital sign that liesNeuromuscular patients keep a normal oxygen saturation until they are nearly apnoeic — longer still if they are on supplemental oxygen. Move the numbers and watch the saturation stay reassuring while the airway decision is already overdue.

Forced vital capacity 45 mL/kg

Normal is roughly 60 to 70 mL/kg of ideal body weight — about 4 to 5 L in an average adult.

Negative inspiratory force −60 cm H2O

Normal is more negative than −60 cm H2O. Dragging right makes it less negative — weaker.

Maximal expiratory pressure 80 cm H2O

Below 40 cm H2O is the third leg of the 20/30/40 rule — and it is the number that predicts a cough too weak to clear secretions.

Single-breath count 25

One full breath, counting aloud at a normal pace. Into the twenties suggests reasonable reserve; the low teens or below is a warning.

Oxygen saturation on room air 96%

Can lift the head off the pillow and hold it for 5 seconds

Bulbar signs present — nasal or slurred speech, wet voice, weak cough, trouble handling secretions

What the profile says