Neuromuscular Disorders of the Critically Ill Patient:

Effect of critical illness polyneuropathy on the withdrawal from mechanical ventilation and the length of stay in septic patients*

OBJECTIVES

No previous study has demonstrated whether critical illness polyneuropathy itself lengthens mechanical ventilation or whether this prolonged duration of ventilatory support is explained by concomitant risk factors for weaning failure. Our objectives were to evaluate the impact of critical illness polyneuropathy on the length of mechanical ventilation after controlling for coexisting risk factors for weaning failure and to assess the impact of critical illness polyneuropathy on the length of the stay in a cohort of septic patients.

DESIGN

Prospective cohort study.

SETTING

Intensive care unit of a tertiary hospital.

PATIENTS

All patients with severe sepsis or septic shock who required mechanical ventilation for > or =7 days who were considered ready to discontinue mechanical ventilation.

INTERVENTIONS

Patients underwent a neurophysiologic evaluation at onset of weaning from mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

Sixty-four critically ill septic patients were enrolled, and 34 developed critical illness polyneuropathy (53.1%; 95% confidence interval, 40.2-65.7%). Length of mechanical ventilation was significantly higher in patients who had developed critical illness polyneuropathy (median 34 days vs. 14 days, p < .001). The duration of the weaning period was also significantly greater in patients with critical illness polyneuropathy (median 15 days vs. 2 days, p < .001) even though factors suspected to influence the weaning process did not differ between these two groups. Multiple logistic regression analysis indicated that critical illness polyneuropathy was the only risk factor independently associated with weaning failure (odds ratio, 15.4; 95% confidence interval, 4.55, 52.3; p < .001). Lengths of intensive care unit and hospital stays were significantly higher in patients with critical illness polyneuropathy.

CONCLUSIONS

In critically ill septic patients, critical illness polyneuropathy significantly increases the duration of mechanical ventilation and prolongs the lengths of intensive care unit and hospital stays.

Steroid-induced myopathy in patients intubated due to exacerbation of chronic obstructive pulmonary disease

OBJECTIVE

To determine incidence, risk factors and impact on various outcome parameters of the development of acute quadriplegic myopathy in a selected population of critically ill patients.

SETTING

A prospective cohort study carried out in the intensive care unit of a tertiary-level university hospital.

PATIENTS

All patients admitted due to acute exacerbation of chronic obstructive pulmonary disease who required intubation and mechanical ventilation, and received high doses of intravenous corticosteroids.

INTERVENTIONS

A neurophysiological study was performed in all cases at the onset of weaning. Muscular biopsy was taken when the neurophysiological study revealed a myopathic pattern.

MEASUREMENTS AND RESULTS

Twenty-six patients were enrolled in the study. Nine patients (34.6%) developed myopathy. Only seven patients were treated with muscle relaxants. Histology confirmed the diagnosis in the three patients who underwent muscle biopsy. APACHE II score at admission, the rate of sepsis and the total doses of corticosteroids were significantly higher in patients with myopathy compared with those patients that did not develop it. Myopathy is associated with an increase in the duration of mechanical ventilation [15.4 (9.2) versus 5.7 (3.9) days; p<0.006], the length of ICU stay [23.6 (10.7) versus 11.4 (7.05) days; p<0.003] and hospital stay [33.3 (19.2) versus 21.2 (16.1) days; p<0.034)]. Myopathy was not associated with increased mortality.

CONCLUSIONS

In the population under study, severity of illness at admission, the development of sepsis and the total dose of corticosteroids are factors associated with the occurrence of myopathy after the administration of corticosteroids. Myopathy was associated with prolonged mechanical ventilation and in-hospital stay.