title: Phrenic nerve conduction studies in patients with chronic obstructive pulmonary disease.
abstract: BACKGROUND
  The most common etiology of hypercapnic respiratory failure is chronic obstructive pulmonary disease (COPD). However, the differential diagnosis also includes neuromuscular disorders. We studied the specificity of reduced amplitude phrenic nerve compound motor action potential (CMAP) to diagnose neuromuscular disorders.
  
  
  METHODS
  A group of patients with advanced COPD were recruited prospectively and compared with controls. Phrenic nerve CMAPs were measured bilaterally using supraclavicular surface stimulation and bipolar recording (G1: 5 cm above the xiphoid; G2: 16 cm from G1).
  
  
  RESULTS
  A group of 20 patients (15 men) and a group of 29 controls (15 men) were included. Phrenic nerve CMAPs of patients with COPD had significantly longer latency and higher amplitude.
  
  
  CONCLUSIONS
  Our study demonstrates that patients with hypercapnic respiratory failure and reduced phrenic nerve CMAP amplitude most probably have a neuromuscular disorder affecting the diaphragm and not COPD or another lung disorder.
authors: Institute of Clinical Neurophysiology, Division of Neurology, University Medical Center, SI-1525 Ljubljana, Slovenia. simon.podnar@kclj.si
authors: Simon
authors: S
authors: Podnar
authors: Matevž
authors: M
authors: Harlander
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D003943:Diagnostic Techniques, Neurological; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000175:diagnosis / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D009468:Neuromuscular Diseases / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D010791:Phrenic Nerve / Q000503:physiopathology*; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000209:etiology; D012680:Sensitivity and Specificity