Signs of critical illness polyneuropathy and myopathy can be seen early in the ICU course

Critical illness polyneuropathy and myopathy (CIPNM) is recognized as a common condition that develops in the intensive care unit (ICU). It may lead to a prolonged hospital stay with subsequent increased ICU and hospital costs. Knowledge of predisposing factors is insufficient and the temporal pattern of CIPNM has not been well described earlier. This study investigated patients with critical illness in need of prolonged mechanical ventilation, describing comprehensively the time course of changes in muscle and nerve neurophysiology, histology and mitochondrial oxidative function.

Ten intensive care patients were investigated 4, 14 and 28 days after the start of mechanical ventilation. Laboratory tests, neurophysiological examination, muscle biopsies and clinical examinations were performed. Neurophysiological criteria for CIPNM were noted and measurements for mitochondrial content, mitochondrial respiratory enzymes and markers of oxidative stress were performed.

While all patients showed pathologic changes in neurophysiologic measurements, only patients with sepsis and steroid treatment (5/5) fulfilled the CIPNM criteria. The presence of CIPNM did not affect the outcome, and the temporal pattern of CIPNM was not uniform. All CIP changes occurred early in ICU care, while myopathy changes appeared somewhat later. Citrate synthase was decreased between days 4 and 14, and mitochondrial superoxide dismutase was increased.

With comprehensive examination over time, signs of CIPNM can be seen early in ICU course, and appear more likely to occur in patients with sepsis and corticosteroid treatment.