Utility of phrenic nerve conduction studies for identification of patients with neuromuscular diseases requiring invasive mechanical ventilation

Introduction/aims: Predicting when a patient will require invasive mechanical ventilation (IMV) is a major challenge in routine care for some neuromuscular diseases. In this study, we prospectively investigated whether phrenic nerve conduction studies (PNCS) can predict when IMV will be required in patients with amyotrophic lateral sclerosis (ALS), Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and myotonic dystrophy (DM).

Methods: PNCS amplitude (avAMP) and latency (avLAT) were compared between patients who required IMV (IMV group) and those who did not (non-IMV group). PNCS were performed in 62 healthy controls and in patients with four different diseases that may require IMV: ALS (n = 56), GBS (n = 72), CIDP (n = 38), and DM (n = 24).

Results: The IMV group consisted of 12 patients with ALS, 14 with GBS, 2 with CIDP, and 4 with DM. avAMP was significantly lower in the IMV group with ALS than in the non-IMV group (P < .05), but no significant difference was observed in avLAT. avAMP was significantly lower and avLAT was significantly longer in the IMV group with GBS than in the non-IMV group (both P < .05). Receiver operating characteristic analysis showed that the avAMP cutoff between the IMV and non-IMV groups was 184.3 μV (area under the curve = 0.921; sensitivity, 84.6%; specificity, 88.2%) for ALS and GBS.

Discussion: PNCSs may aid in determining whether a patient with ALS or GBS requires IMV.