Physiology
- Pulmonary HTN due to neuromuscular disease (due to bilateral diaphragmatic paresis or paralysis)
- Hypoventilation leads to hypoxia/acidosis (with resultant pulmonary vasoconstriction)
Etiology
- Polydermatomyositis (see [[Polydermatomyositis]])
- xxx
Diagnosis
- PFT (restriction):
- Decreased VC (due to muscle weakness, decreased lung, chest wall compliance): supine VC << upright VC (normals show approximate 20% decrease with change in position, but Bilateral Diaphragmatic Paralysis patients show >25-50% decrease)
- Decreased TLC
- Increased RV (due to inability to overcome recoil of chest wall outward at volumes below FRC)
- Decreased MVV
- Decreased MIP/ MEP
- Decreased compliance (due to chronically low lung volumes: microatelectasis/ reduced surface tension/ altered interstitial elastic fibers)
- Transdiaphragmatic pressure (with esophageal and gastric balloons): reveals decreased pressure gradient
- CXR: low lung volumes/ possibly aspiration pneumonia
- Diaphragmatic EMG/ NCV: may reveal myopathic changes, neuropathic changes, anterior horn cell disease
Clinical
(usually symptomatic)
- Exertional dyspnea
- Orthopnea (due to pressure of viscera on diaphragm)
- Dullness/ decreased BS at bases
- Tachypnea (in severe disease)
- Scalene/Sternocleidomastoid contractions
- Paradoxic inward movement of abdomen with inspiration (classic)
- Respiratory failure
- Aspiration pneumonia
- Sleep-disordered breathing
- Acute/Chronic Hypoventilation (see Acute Hypoventilation, [[Acute Hypoventilation]] and Chronic Hypoventilation, [[Chronic Hypoventilation]])
- Pulmonary Hypertension/Cor Pulmonale (see Pulmonary Hypertension, [[Pulmonary Hypertension]])
Treatment
- xxx
References
- xxx