Ambulatory Report – 1.5.17 – PFTs, MMN, and the 20-30-40 Rule

Thanks to Matt Schwede and Joe Sanford for presenting a case of an 84 yo M with a history of multifocal motor neuropathy, COPD, and AV block presenting with progressive SOB, thought possibly 2/2 to his multifocal motor neuropathy as well as possible IPF.
  • Pulmonary Function Testing
    • This is a previous Evernote about PFTs that I put together (with real teaching cases and answers that you can use to teach others!)
    • This is a schematic stepwise approach to analyzing PFTs.  It is by no means exhaustive, but provides a basic first pass analysis.
      • pft-approach-sha
  • Multifocal Motor Neuropathy (MMN) – the Quick & Dirty
    • Thought to be an immune-mediated that often responds to IVIG (usually need to treat ever 2-6 weeks)
    • Typical presentation = subacute onset, asymmetric weakness, patchy neuron involvement, progressive arm & hand weakness w/o sensory loss
      Can see anti-GM1 antibodies in 30-80%=
    • Nerve conduction studies – often show focal demyelination & conduction block
  • Respiratory Distress 2/2 Neuromuscular Disease – the 20-30-40 rule
    • Consider ventilatory support when:
      • Vital Capacity is < 20 cc/kg
      • Max Inspiratory Pressure (MIP) < -30 cm H2O
      • Max Expiratory Pressure (MEP) < 40 cm H2O

Evernote Link:


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