Critical illness polyneuromyopathy: a major problem in a general intensive care unit

Introduction

Critical illness polyneuromyopathy (CIPM) constitutes a significant cause of difficulty in weaning patients from the ventilator, prolongation of their stay in the ICU and increased morbidity and mortality. No reliable global epidemiologic data exist to define the overall prevalence and incidence of CIPM in ICU patients.

Objectives

To estimate the clinical incidence and prevalence of CIPM in the general ICU setting.

Patients and methods

From August to December 2004, 205 consecutive admissions in a 25-bed university general ICU were evaluated. Thirty-four patients were discharged in less than 24 hours from admission and were excluded from the study. The remaining 171 patients (119 males, 52 females, mean age: 52 ± 18 years) were assigned admission APACHE II (17 ± 8) and SOFA (7 ± 3) scores and were evaluated for the development of new onset polyneuromyopathy, detected by assessing muscle strength reduction (by the Medical Research Council scale), reduced/absent deep tendon reflexes, sensory involvement and clinically evident muscle wasting. Biochemical parameters and drug treatment were evaluated daily. Other possible causes of acute weakness appearing after ICU admission were excluded. Prevalence of CIPM was estimated clinically on two different occasions. All continuous variables are presented as the mean ± standard deviation.

Results

Twenty (12%) out of the 171 enrolled patients developed CIPM. One hundred and five patients (71 males, 34 females) had an ICU stay of more than 7 days, with an admission APACHE II score of 18 ± 7 and a SOFA score of 8 ± 3. Nineteen percent of those patients developed CIPM. All affected patients had an ICU stay of more than 7 days. Patients with CIPM (13 males, seven females) had a higher admission APACHE II (21 ± 8 vs 16 ± 7; P < 0.02) and SOFA (82 vs 7 ± 3; P = 0.05) score and a longer ICU stay (29 ± 21 vs 12 ± 13 days; P < 0.001) than those without CIPM (151 patients). The overall mortality rate was 22%. Thirty-five percent of patients with CIPM died during their ICU stay, compared with 21% of patients without CIPM. Regarding age, no statistically significant difference was found among the two groups. Prevalence of CIPM in the ICU was estimated to be 20%.

Conclusions

Previous prospective studies have reported higher incidence rates for CIPM by studying subgroups of patients with severe sepsis/systemic inflammatory response syndrome. Our data show a high incidence and prevalence of CIPM in a general consecutive ICU population. This finding clearly illustrates the need for a longer prospective study to investigate the pathophysiologic mechanisms, as well as the risk factors involved.