Diaphragmatic Palsy
OVERVIEW
- unilateral and bilateral
- unilateral can be asymptomatic depending on patients underlying respiratory reserve
- bilateral -> most mechanical ventilation dependent
CAUSES
Unilateral
- malignancy (metastatic lung cancer) – 30% of causes
- idiopathic
- HZV
- cervical spondylosis
- trauma
- post thoracic surgery
Bilateral
- motor neuron disease
- post-polio syndrome
- amyotrophic lateral sclerosis
- cardiac surgery
- thoracic trauma
- MS
- muscular dystrophy
DIAGNOSIS
- ABG: arterial hypercapnoea +/- hypoxaemia
- CXR: elevated hemidiaphragms, small lung volumes, atelectasis
- fluoroscopic sniff test: diaphragm paradoxically moves upward on inspiration
- ultrasound: can also perform sniff test
- CT: looking for cause in chest
- MRI: looking for cause in spinal cord
- Spirometry: VC (change with posture)
- EMG: may reveal neuropathic or myopathic cause
- Transdiaphragmatic pressure: balloon inserted into stomach and oesophagus -> pressure difference measured
PHYSIOLOGICAL CONSEQUENCES
- normally VC decreases by 10% on going from upright to supine
- in unilateral paralysis -> VC decreases by 80%
- in bilateral paralysis -> VC decreases by 50% because of cephalad displacement of abdominal contents
- SOB proportional to unilateral or bilateral palsy and respiratory function
- hypercapnic respiratory failure
MANAGEMENT
Unilateral
- asymptomatic -> nothing
- surgical plication (VATS) -> diaphragm can no longer move paradoxically during inspiration -> decreases symptoms
Bilateral
- if phrenic nerves intact -> diaphragmatic pacing
- ventilatory support (NIV -> IPPV)
References and Links
- Gibson GJ. Diaphragmatic paresis: pathophysiology, clinical features, and investigation. Thorax. 1989 Nov;44(11):960-70. PMC462156.
- Nason LK, Walker CM, McNeeley MF, Burivong W, Fligner CL, Godwin JD. Imaging of the diaphragm: anatomy and function. Radiographics. 2012 Mar-Apr;32(2):E51-70. doi: 10.1148/rg.322115127. PMID: 22411950. [Free Full Text]
Critical Care
Compendium
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.
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