Bilateral Diaphragm Paralysis case

Question 1

What symptoms may a patient with phrenic palsy present with
What signs may a patient present with
-why does this happen

Answer 1

SOB
General muscle weakness
Orthopnea

Abdominal wall moves down when inspiring

• normally would move up
• when lying down, abdominal contents fall into the diaphragm but the diaphragm is unable to push back
• when inspiring, the diaphragm is unable to move against the -ve thoracic pressure

Question 2

What are the potential causes of phrenic palsy?

VITAMIN CDEF

Answer 2

Iatrogenic/idiopathic

• sedative drugs
• surgery

Trauma

• head injury
• SC/phrenic injury affecting C3-5

Autoimmune
-Myasthenia gravis

Metabolic
-Pompes

Inflammatory/infective
-
Neoplastic
-
Congenital
-DMD

Degenerative

• Disc prolapse => nerve root injury
• MND
• COPD

Functional
-

Question 3

What would spirometry and lung function tests show
-use the LFT algorithm
What test would confirm the diagnosis

Answer 3

Peak flow
-low

FEV1, FVC
-low
FER
-normal or high => restrictive issue affecting lung volume (low TLC when lying down)

RV
-slightly high (requires more external force to push air out in expiration, so not a stiff lung issue)

TLCO, KCO
-normal => extrapulmonary cause interfering with lung expansion

If TLC measured when standing and lying, there should be a marked difference between the 2

Question 4

What would an ABG show
What would the Aa gradient show
How would you manage this case

Answer 4

pH: normal
PO2: low, hypoxemia
PCO2: high, hypercapnia
HCO3: high, especially if this is chronic

Aa gradient likely to be normal
-not an issue with the alveolar capillary exchange surface
Type 2 resp failure => NIV