Neuromuscular disease Flashcards
What are the 4 levels of pathologic injury in NMD?
Upper motor neuron
Lower motor neuron
Neuromuscular junction
Muscle
What is the normal response to oxygen desaturation vs the normal response to a decrease in PaCO2?
SpO2 = Linear, 1% decrease in sat = 1 L/m increase in minute ventilation
PaCO2 = Steep linear, 1 mmHg increase in PaCO2 = 2.5-3 L/m increase in MV
Describe how patients with NMD respond to changes in O2 sat and PaO2
Exhibit a significantly decreased response
Describe how mouth occlusion pressure is tested
Mouth occlusion pressure is tested by measuring the negative pressure produced during the first 100 milliseconds of inhalation with complete airway occlusion
How can respiratory drive be demonstrated?
Mouth occlusion pressure
What nerves innervate the muscles of expiration?
Lumbar
Intercostal
Why is mouth occlusion pressure an effective measure of respiratory drive?
It is measured so early in the breath that it cannot be voluntarily interfered with
Requires only a fraction of total muscle strength so it remains viable even in severely compromised patients
What nerves innervate the upper airways?
Glossopharyngeal
Vagus
Spinal accessory
Hypoglossal
What nerves innervate the muscles of inspiration?
Phrenic
Cervical
Intercostal
Spinal accessory
When does hypercapnia develop in relation to NIF score?
Once NIF declines to less than 30% of predicted, hypercapnia develops
What might a patient with NMD complain of besides dyspnea?
Fatigue
Poor sleep
Dyspnea on exertion
Why might a patient with a NMD develop sleep apnea?
Damage or disorders of the nerves may be more readily apparent at night when conscious control of breathing is absent and cannot compensate
Why can a patient with NMD develop decreased lung compliance?
Microatelectasis from reduced respiratory muscle strength \
Increases alveolar surface tension from low lung volumes
Sedentary lifestyle contributing to low tidal breaths
Why can the chest wall of a patient with NMD become stiff?
Chest wall structures such as tendons ligaments and costosternal articulations can grow stiff due to lack of physical movement from large breaths
What should be measured routinely in NMD patients in order to track the progression of the disease process?
Maximum inspiratory pressure
Maximum expiratory pressure
How can transdiaphragmatic pressure be measured?
Catheter with a balloon goes to mid esophagus (Pes), catheter with a balloon goes to (Pga) and the pressure difference is recorded to give us transdiaphragmatic pressure
In patient with diaphragmatic weakness, which position would be provide for a better FVC?
Upright
In patients with spinal cord injuries, which position would be better for providing a greater FVC?
Supine