Feasibility and diagnostic accuracy of early electrophysiological recordings for ICU-acquired weakness: an observational cohort study.
BACKGROUND
An early diagnosis of ICU-acquired weakness (ICU-AW) is difficult because disorders of consciousness frequently preclude muscle strength assessment. In this study, we investigated feasibility and accuracy of electrophysiological recordings to diagnose ICU-AW early in non-awake critically ill patients.


METHODS
Newly admitted patients, mechanically ventilated ≥2 days and unreactive to verbal stimuli, were included in this study. Electrophysiological recordings comprised nerve conduction studies (NCS) of three nerves and, if coagulation was normal, myography in three muscles. Upon awakening, strength was assessed (ICU-AW: average Medical Research Council score <4), blinded for electrophysiological recordings. Feasibility was expressed as the percentage of recordings that were both possible and had sufficient technical quality. Diagnostic accuracy of feasible (i.e., feasibility >75 %) recordings was analyzed based on cut-off values from healthy controls and from critically ill patients with and without ICU-AW.


RESULTS
Thirty-five patients were included (17 with ICU-AW). Recordings were obtained on day 4 (IQR: 3-6). Feasibility was acceptable for ulnar and peroneal nerve recordings, and low for sural recordings and myography. Diagnostic accuracy based on cut-off values from healthy controls was low. When using cut-off values from critically ill patients with and without ICU-AW, the peroneal compound muscle action potential amplitude and ulnar sensory nerve action potential amplitude had good diagnostic accuracy.


CONCLUSIONS
Nerve conduction studies of the ulnar and peroneal nerve are feasible in critically ill patients. The diagnostic accuracy is low using cut-off values from healthy controls. Cut-off values validated specifically for discrimination between critically ill patients with and without ICU-AW may improve diagnostic accuracy.
Department of Intensive Care Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, room C3-311, PO box 22700, 1105 AZ, Amsterdam, The Netherlands, l.wieske@amc.uva.nl.
Luuk
L
Wieske
Camiel
C
Verhamme
Esther
E
Witteveen
Aline
A
Bouwes
Daniela S
DS
Dettling-Ihnenfeldt
Marike
M
van der Schaaf
Marcus J
MJ
Schultz
Ivo N
IN
van Schaik
Janneke
J
Horn
D000200:Action Potentials / Q000502:physiology; D015331:Cohort Studies; D003422:Critical Care; D004576:Electromyography; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000175:diagnosis* / Q000209:etiology; D009431:Neural Conduction / Q000502:physiology*; D012680:Sensitivity and Specificity