Pulmonary Function/Spirometry
Your first appointment with a Neuromuscular breathing specialist should include pulmonary function testing (PFT) or manual spirometry. Tests should be done to measure Forced Vital Capacity (FVC) in both the seated and supine (reclined) positions. If a body brace is used, the measurement should be taken with it on and off. In many forms of Neuromuscular Disease (NMD), supine FVC can reveal diaphragm weakness that otherwise would be unknown if the testing were performed only while seated.
“A sitting-supine difference of greater than 7% is abnormal. Differences greater than 30% (supine VC lower), which are caused by diaphragm weakness, usually cause “orthopnea” or inability to breathe when lying flat and indicate the need to introduce sleep NVS to breathe when reclining.” Note: VC is Vital Capacity. NVS is Noninvasive Ventilatory Support. Reference: https://www.breathenvs.com/e-m-older-children-and-adults
Additional measures of breathing muscle strength should be taken such as Maximum Inspiratory Pressure (MIP) and Maximum Expiratory Pressure (MEP).
“Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) maneuvers (21) can help track respiratory muscle weakness even in the absence of overall muscle weakness (22), and reduced MIP and MEP are associated with likelihood for hypoventilation and respiratory failure in many conditions, particularly myopathies (23).” Note: Hypoventilation means under ventilation. Reference: https://www.annualreviews.org/doi/full/10.1146/annurev-med-043021-013620?fbclid=IwAR01DuzY3GadHshXfK3jj5BHcdS6_2urJgRaX98hOTAAUjUu4GlxJgEKC_U
Peak Cough Flow (PCF) can determine cough weakness and risk for respiratory infection. A peak cough expiratory flow (PCEF) of <270 L/min may be sufficient to clear mucus when an individual with NMD is well but puts them at risk of having a weak, ineffective cough during respiratory illnesses. Learn more about weak, ineffective cough on our “Cough in Neuromuscular Disease” page.
Other assessments that may be done include resting lung volume functional residual capacity (FRC) by helium dilution technique and sniff nasal inspiratory pressure (SNIP), which may be used in place of MIP since it is a more natural breathing maneuver. Reference: https://www.curecmd.org/_files/ugd/274224_31b555d13dde45d1a964aec9fef46996.pdf
See also:
Blood Gases
Sleep Study
Swallowing
Your first appointment with a Neuromuscular breathing specialist should include pulmonary function testing (PFT) or manual spirometry. Tests should be done to measure Forced Vital Capacity (FVC) in both the seated and supine (reclined) positions. If a body brace is used, the measurement should be taken with it on and off. In many forms of Neuromuscular Disease (NMD), supine FVC can reveal diaphragm weakness that otherwise would be unknown if the testing were performed only while seated.
“A sitting-supine difference of greater than 7% is abnormal. Differences greater than 30% (supine VC lower), which are caused by diaphragm weakness, usually cause “orthopnea” or inability to breathe when lying flat and indicate the need to introduce sleep NVS to breathe when reclining.” Note: VC is Vital Capacity. NVS is Noninvasive Ventilatory Support. Reference: https://www.breathenvs.com/e-m-older-children-and-adults
Additional measures of breathing muscle strength should be taken such as Maximum Inspiratory Pressure (MIP) and Maximum Expiratory Pressure (MEP).
“Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) maneuvers (21) can help track respiratory muscle weakness even in the absence of overall muscle weakness (22), and reduced MIP and MEP are associated with likelihood for hypoventilation and respiratory failure in many conditions, particularly myopathies (23).” Note: Hypoventilation means under ventilation. Reference: https://www.annualreviews.org/doi/full/10.1146/annurev-med-043021-013620?fbclid=IwAR01DuzY3GadHshXfK3jj5BHcdS6_2urJgRaX98hOTAAUjUu4GlxJgEKC_U
Peak Cough Flow (PCF) can determine cough weakness and risk for respiratory infection. A peak cough expiratory flow (PCEF) of <270 L/min may be sufficient to clear mucus when an individual with NMD is well but puts them at risk of having a weak, ineffective cough during respiratory illnesses. Learn more about weak, ineffective cough on our “Cough in Neuromuscular Disease” page.
Other assessments that may be done include resting lung volume functional residual capacity (FRC) by helium dilution technique and sniff nasal inspiratory pressure (SNIP), which may be used in place of MIP since it is a more natural breathing maneuver. Reference: https://www.curecmd.org/_files/ugd/274224_31b555d13dde45d1a964aec9fef46996.pdf
See also:
Blood Gases
Sleep Study
Swallowing