Diaphragmatic Palsy


  • unilateral and bilateral
  • unilateral can be asymptomatic depending on patients underlying respiratory reserve
  • bilateral -> most mechanical ventilation dependent



  • malignancy (metastatic lung cancer) – 30% of causes
  • idiopathic
  • HZV
  • cervical spondylosis
  • trauma
  • post thoracic surgery


  • motor neuron disease
  • post-polio syndrome
  • amyotrophic lateral sclerosis
  • cardiac surgery
  • thoracic trauma
  • MS
  • muscular dystrophy


  • 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


  • 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



  • asymptomatic -> nothing
  • surgical plication (VATS) -> diaphragm can no longer move paradoxically during inspiration -> decreases symptoms


  • 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]

CCC 700 6

Critical Care


Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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