Weaning from mechanical ventilation in myasthenic crisis according to WEAN safe: most patients experience intermediate or prolonged weaning with no differences between early and late-onset compared to very-late onset myasthenia Gravis.

Abstract

Background: Myasthenic crisis often requires prolonged mechanical ventilation and complex weaning, yet data remain scarce. The objective of this study was to describe the weaning characteristics in patients with myasthenic crisis using the WEAN Safe classification. Secondary aims included assessment of long-term outcome and comparison between early- and late-onset (< 65 years) versus very-late-onset MG (≥ 65 years) myasthenia gravis.

Methods: This single-center retrospective study included patients admitted for myasthenic crisis to a tertiary neuro-intensive care unit between January 2008 and December 2023. Clinical characteristics, ventilatory support parameters, timing of weaning events, complications, and outcomes were recorded. Weaning was classified according to WEAN Safe definitions: no separation attempt, short wean (successful weaning within 1 day), intermediate wean (2-6 days), prolonged wean (≥ 7 days), or failed wean (persistent invasive ventilation at discharge or death).

Results: Among 698 ICU hospitalizations (405 patients) for myasthenia gravis, 131 (120 patients) received invasive mechanical ventilation. Fifty hospitalizations (39 patients) were excluded due to non-MC-related intubation, insufficient weaning data or patients with multiple ICU admissions. The final analysis included 81 patients (median age 70 years [54-81]; 43% female; 64% with very-late-onset myasthenia gravis (≥ 65 years). The median duration of mechanical ventilation was 20 days [11-38], and the median time from the first separation attempt to successful weaning was 7 days [3-19]. According to the WEAN Safe classification, 3% had a short wean, 40% intermediate, 55% prolonged, and 3% failed weaning. Four patients (5%) required reintubation within 48 h. Ventilator-associated pneumonia occurred in 15% of patients before the first separation attempt. In multivariate analysis, the presence of thymoma (OR 3.02, 95% CI 1.01-9.07) and absence of MG-specific immunosuppressive treatment at ICU admission (OR 3.70, 95% CI 1.22-11.23) were independently associated with prolonged weaning. Intensive care unit mortality was 7%, and 12-month mortality was 19%. The median myasthenic muscle score at 1 year was 94/100 [80-100]. No significant differences in weaning parameters nor outcome were found between early- and late-onset versus very-late-onset MG, despite more comorbidities in the very-late-onset group.

Conclusions: In this retrospective study from a single expert center, most patients with myasthenic crisis underwent intermediate or prolonged weaning, but extubation failure rate was very low. Thymoma and lack of MG-specific immunosuppressive treatment at ICU admission are associated with prolonged weaning, while age alone is not. Despite initial challenges, long-term outcomes are generally favorable, highlighting the reversibility of myasthenic crisis with expert care.