Prevalence of and Risk Factors for Mechanical Ventilation Reinstitution in Patients Weaned From Prolonged Mechanical Ventilation

Abstract

Background: Prolonged mechanical ventilation is increasingly common in ICUs. Although a consensus conference defined weaning success in this patient population, few studies have used this definition. A clear definition of successful weaning is useful to assess clinical and epidemiological outcomes, facilitate clinical decision making, and set goals of care. The aims of our study were to describe the prevalence of reinstitution of mechanical ventilation within 28 d in patients successfully weaned according to our institution criterion (ie, weaning success as per consensus guidelines), to describe reasons to reestablish mechanical ventilation, and to identify associated factors.

Methods: An observational, analytical, cross-sectional study was conducted at a weaning and rehabilitation center. All patients liberated from mechanical ventilation (ie, no ventilatory support for 7 d) were included as subjects. Requirement of and reasons for reinstitution of mechanical ventilation within 28 d of weaning were recorded.

Results: A total of 639 tracheostomized subjects were analyzed. Of these, 219 (34%) were weaned, and 15 were eliminated due to lack of data. Of the remaining 204 subjects, 42 (21%) were reconnected to mechanical ventilation within 28 d. Sepsis accounted for 64% of reconnections. In the multivariate analysis, neurological comorbidity (adjusted odds ratio 5.1 [95% CI 2.3-11.1]) and delayed weaning (> 7 d after admission) (adjusted odds ratio 2.37 [95% CI 1.1-5.3]) were independently associated with reinstitution of mechanical ventilation within 28 d of weaning. The synergistic effect of both variables showed an adjusted odds ratio of 5.35 (95% CI 2.4-11.4).

Conclusions: Reinstitution of mechanical ventilation within 28 d is a common event in patients considered to be weaned: 1 in 5 of such patients requires reconnection to mechanical ventilation, with sepsis being the most prevalent cause. Neurological comorbidity and delayed weaning are risk factors associated with reestablishment of mechanical ventilation. The presence of more than one risk factor increases the association with reinstitution of mechanical ventilation within 28 d of weaning.

Keywords: chronic disease; mechanical ventilation; rehabilitation; risk factors; treatment outcome; ventilator weaning.