Diaphragm weakness associated with critical illness can be diagnosed if certain findings are present.
Parameters:
(1) diaphragm thickening fraction (TFdi) on ultrasound in percent
(2) diaphragm excursion (EXdi) on ultrasound with patient disconnected from ventilator, in cm
(3) maximal transdiaphragmatic pressure (Pdi max) in cm H2O
(4) endotracheal pressure induced by bilateral magnetic stimulation of the phrenic nerve (Pet, tw) in cm H2O
(5) transdiaphragmatic pressure induced by bilateral magnetic stimulation of the phrenic nerve (Pdi,tw) in cm H2O
(6) ratio of inspiratory Pga swings to Pdi swings (delta Pga to delta Pdi)
|
Parameter
|
Diaphragmatic Weakness
|
|
TFdi
|
< 20%
|
|
EXdi
|
< 1 cm
|
|
Pdi max
|
< 60 cm H2O
|
|
Pet, tw
|
< -11 cm H2O
|
|
Pdi, tw
|
< -10 cm H2O
|
|
delta Pga to delta Pdi
|
< 0
|
Additional means of evaluation:
(1) diaphragm electromyography (EMG)
(2) crural diaphragm activity (EAdi)
