Does obesity impact on weaning from invasive ventilation: a secondary analysis of the WEAN SAFE study

Annals of Intensive Care volume 15, Article number: 164 (2025) Published: 21 October 2025

Objective

To understand the impact of obesity on outcomes of weaning from invasive mechanical ventilation (MV).

Methods

The study population consisted of patients enrolled in the WEAN SAFE study. We defined 4 groups based on body mass index (BMI), namely: Normal weight (BMI 18.5–24.9 kg/m²), Overweight (BMI 25–29.9 kg/m²), Obesity Class I (BMI 30–34.9 kg/m²), and obesity classes II and III (BMI ≥ 35 kg/m²). The primary outcome was the rate of successful extubation in patients in each BMI group. Secondary outcomes included the ICU and hospital survival, and PEEP levels at time of weaning eligibility in patients in each BMI group.

Results

In the study population, 1728 (38.2%) were of normal weight, 1395 (30.8%) were overweight, 590 (13.1%) were class I Obesity, and 431 (9.5%) were obesity classes II and III. Patients with obesity were more likely to be female, to be a medical admission, and to have comorbidities. Patients with grade II-III obesity had lower levels of sedation, later timing of the first separation attempt, longer time to weaning success, they received more noninvasive ventilation post extubation, and they had a longer ICU stay. In contrast, weaning success, and ICU and hospital mortality rates were not different in obese patients. There was no independent relationship between obesity and weaning delay, weaning success, or with overall survival outcomes. Higher PEEP at weaning eligibility was associated with weaning failure in normal and overweight patients but not in patients with obesity.

Conclusions

Patients with obesity had a more complex and longer weaning process, but obesity per se was not independently associated with adverse weaning outcomes.

 

 

 

Impact of frailty and older age on weaning from invasive ventilation: a secondary analysis of the WEAN SAFE study

Annals of Intensive Care volume 15, Article number: 13 (2025)

Published: 20 January 2025

Objective

To understand the impact of both frailty and chronologic age on outcomes of weaning from invasive mechanical ventilation (MV).

Methods

The study population consisted of patients enrolled in the ‘WorldwidE. AssessmeNt of Separation of pAtients From ventilatory assistancE (WEAN SAFE) study. We defined 4 non-overlapping groups, namely: ‘frail’ (clinical frailty scale [CFS] score > 4; age < 80 years); ‘elderly’ (CFS ≤ 4; age ≥ 80y), ‘frail \elderly’ (CFS > 4; age ≥ 80 years), and a ‘not frail or elderly’ population. The primary outcome was the impact of frailty and older age on delayed weaning and failed weaning from invasive MV. Secondary outcomes included the impact of frailty and age on ICU and hospital survival.

Results

In the study population, 760 (17%) were frail, while 360 (8%) were elderly, 197 (4%) were frail and elderly, while 3,176 (70%) were not frail or elderly. The frail and elderly cohorts were more likely to be female, had hypoxemic/hypercapnic respiratory failure or sepsis, and had more comorbidities. The proportion of delayed weaning and of failed weaning from invasive MV was significantly higher in the frail (28 and 23%), the elderly (25 and 19%), and the frail and elderly groups (22% and 25%), compared to the not frail or elderly population (12% and 13%, P < 0.01). ICU and hospital mortality was higher in the frail (21 and 33%), the elderly (19 and 31%), and the frail and elderly groups (26 and 46%), compared to the not frail or elderly population (12% and 18%, P < 0.001). In multivariate analyses, there was an independent association between frailty and delayed weaning initiation and weaning failure. Old age was independently associated with risk of weaning failure.

Conclusions

Frailty status had a more consistent impact than older age on weaning outcomes. However, overall outcomes in these cohorts are encouraging once separation attempts have been initiated.