PREDOMINANT INVOLVEMENT OF MOTOR FIBERS IN PATIENTS WITH CRITICAL ILLNESS POLYNEUROPATHY

Critical illness polyneuropathy (CIP) is a recognized cause of muscle weakness and failure of weaning from a ventilator. In order to charact erize the features of CIP, we have examined 28 consecutive surgical pa tients with severe sepsis using bedside electrophysiology. Of the 28 p atients (median APACHE II score 31), 20 developed moderate to severe C IP, as shown by the presence of moderate to severe denervation activit y on resting EMG. The median nerve compound muscle action potential (C MAP) amplitudes were reduced to 3.24 (SEM 0.48) mV, while sensory nerv e action potential (SNAP) amplitudes obtained from the same nerve were normal (13.1 (1.9) mu V). In approximately 50% of these patients, the reduction in CMAP exceeded 50% of the lower limit of normal. Similar results were obtained from stimulation of the ulnar nerve. We conclude that CIP is a major complication in patients with severe sepsis and p rolonged artificial ventilation. It predominantly involves motor fibre s and thus markedly interferes with weaning from the ventilator.