Respiratory weakness after mechanical ventilation is associated with one-year mortality - a prospective study

Abstract

BackgroundDiaphragm dysfunction in mechanically ventilated patients is associated with poor outcome. Maximal inspiratory pressure (MIP) can be used to evaluate inspiratory muscle function. However, it is unclear whether respiratory weakness is independently associated with long-term mortality. The aim of this study was to determine if low MIP is independently associated with one-year mortality.MethodsWe conducted a prospective observational cohort study in an 18-bed ICU. Adults requiring at least 24 hours of mechanical ventilation with scheduled extubation and no evidence of pre-existing muscle weakness underwent MIP evaluation just before extubation. Patients were divided into two groups: low MIP (MIP ≤30 cmH2O) and high MIP (MIP >30 cmH2O). Mortality was recorded for one year after extubation. For the survival analysis, the effect of low MIP was assessed using the log-rank test. The independent effect of low MIP on post mechanical ventilation mortality was analyzed using a multivariable Cox regression model.ResultsOne hundred and twenty-four patients underwent MIP evaluation (median age 66 years (25th–75th percentile 56–74), Simplified Acute Physiology Score (SAPS) 2 = 45 (33–57), duration of mechanical ventilation 7 days (4–10)). Fifty-four percent of patients had low MIP. One-year mortality was 31 % (95 % CI 0.21, 0.43) in the low MIP group and 7 % (95 % CI 0.02, 0.16) in the high MIP group. After adjustment for SAPS 2 score, body mass index and duration of mechanical ventilation, low MIP was independently associated with one-year mortality (hazard ratio 4.41, 95 % CI 1.5, 12.9, p = 0.007). Extubation failure was also associated with low MIP (relative risk 3.0, 95 % CI 1, -9.6; p = 0.03) but tracheostomy and ICU length of stay were not.ConclusionLow MIP is frequent in patients on mechanical ventilation and is an independent risk factor for long-term mortality in ICU patients requiring mechanical ventilation. MIP is easily evaluated at the patient’s bedside.Trial RegistrationThis study was retrospectively registered in www.clinicaltrials.gov (NCT02363231) in February 2015.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1418-y) contains supplementary material, which is available to authorized users.

ICU-acquired weakness, diaphragm dysfunction and long-term outcomes of critically ill patients

“…The association of diaphragm dysfunction with longterm prognosis has never been previously investigated. One study investigated the impact of global respiratory weakness (as assessed by the maximal inspiratory pressure) and reported a higher 1-year mortality (31%) in the group of patients with low maximal inspiratory pressure compared to patients with high maximal inspiratory pressure, in whom the 1-year mortality was 7% [9]. However, limb muscle strength was not analysed in this study.…”

“…It has been clearly established that intensive care unit (ICU)-acquired limb muscle weakness is a frequent condition, associated with poor prognosis [2][3][4][5][6]. Although the consequences of respiratory muscle weakness have been less extensively investigated, some evidences suggest that it may be a risk factor for prolonged duration of mechanical ventilation [7], associated with a higher risk of readmission [8] and higher mortality [9]. Diaphragm dysfunction is frequent in the intensive care unit (more than 60% of mechanically ventilated patients [10]) and is associated with difficult and prolonged weaning and poor Open Access *Correspondence: martin.dres@aphp.fr 1 Service de Pneumologie, Médecine intensive -Réanimation (Département "R3S"), AP-HP, Sorbonne Université, Groupe Hospitalier Universitaire Pitié-Salpêtrière Charles Foix, 75013 Paris, France Full list of author information is available at the end of the article prognosis [11][12][13][14].…”

Diaphragm Dysfunction: Diagnostic Approaches and Management Strategies

“…Finally, in the ICU setting, acquired diaphragm dysfunction has recently grown to become a topic of significant interest because of its negative clinical impact on weaning outcome, length of mechanical ventilation (MV), survival and long-term outcome [51,52,53,54,55,56,57,58,59,60,61,62,63]. One of the main contributors to diaphragm dysfunction in this context is mechanical ventilation, which has been shown to induce significant diaphragm muscle fiber atrophy that can be detected within the first 24 h of MV in humans and even earlier in animal models [64,65,66].…”

“…In the ICU setting, diaphragm dysfunction is associated with adverse prognosis whether it is diagnosed at admission (increased length of stay and mortality) or at the time of weaning from mechanical ventilation (increased weaning failure) [51,52,53,54,55,56,57,58,59,60,61,62,63]. …”

Respiratory Muscle Rehabilitation in Patients with Prolonged Mechanical Ventilation: A Targeted Approach

“…While ICU clinicians have largely focused on whole-body exercise to address limb muscle weakness (e.g., early mobilization), we now know that respiratory muscle weakness is twice as prevalent as limb muscle weakness in ICU patients [2]. Moreover, respiratory muscle weakness is associated with a higher risk of extubation failure [3], a longer duration of ventilator-dependence [4] and worse outcomes in terms of hospital mortality [2] and mortality within 1 year [3]. While ventilator-weaning failure is complex, and respiratory muscle weakness is only one contributing factor [5], this weakness is modifiable and can respond to targeted training.…”