Muscle Assesment

Question 1

Why assess resp muscles?

Answer 1

essential in diagnosis, monitoring of progression of respiratory muscle disorders:
oEspecially Spirometry and VC
oSupine VC
oFall in VC > 30% suggestive of diaphragm weakness/paralysis

Question 2

What are the non-invasive tests used to asses resp muscles.

Answer 2

Measurement of lung function:
oVital Capacity (VC)
•Sitting/Supine VC
oFlow Volume loops
oStatic Lung Volumes
oGas Transfer
•Mouth Pressures
•Sniff Pressures
•Peak Cough Flow
•Sleep studies (e.g. oximetry, transcutaneous

Question 3

What is MAXIMAL EPIRATORY PRESSURE (MEP)?

Answer 3

Measured during a maximum expiratory effort at TLC, against a closed airway

Question 4

WHAT IS Maximal Inspiratory Pressure (MIP)?

Answer 4

Measured during a maximal inspiratory effort from either RV or FRC

If measured from RV, chest wall recoil contributes to the measurement

Question 5

How are the results selected?

Answer 5

At least 3 technically acceptable tests should be performed
•The highest value of the 3 measurements is recorded:
oAim for variability < 1kPa (10cm H2O) or less that 20% across largest 3 values9
oIf last value is largest, 3 additional measurements recorded9
oOr if 2nd largest is < 90% of largest9

Question 6

Normal values for snips and mip are:

Answer 6

> 60/70 cmH2O in females/males respectively excludes significant inspiratory weakness

Question 7

Why might we use Peak Cough Flow (PCF)?

Answer 7

Measurement of PEF & PCF may be easier to perform (e.g. facial muscle weakness)
•Measures strength available for coughing (expiratory muscles)
•Useful if PEmax is low

Question 8

What does it mean when an adults has a PCF of >350l min-1, <270 l min-1 and <160 l min-1

Answer 8

>350= normal
<270= risk of secretion retention
<160= unable to clear their airway