Predictors of outcome in patients with myasthenic crisis undergoing non-invasive mechanical ventilation: A retrospective 20 year longitudinal cohort study from a single Italian center

Non-invasive mechanical ventilation in myasthenic crisis outside intensive care unit setting: a safe step? Response

“…We thank Di Costanzo et al [1] for their interest in our article describing a 20-year experience on 90 patients with myasthenic crisis (MC) undergoing non-invasive ventilatory support (NIV) in the general ward [2] . The comments require attention and might point out the following key question: can NIV be performed safely and successfully in MC outside the intensive care unit (ICU) setting?…”

“…The weakness may involve the respiratory muscles, as demonstrated by the “myasthenic pattern” highlighted by dynamic respiratory tests such as maximal voluntary ventilation [8] . Manifest MC is a severe event with rapid onset; approximately 20% of MG patients experience MC in their lifetime, typically within the first 2 years of the diagnosis [2 , 7] .…”

“…In this context, NIV could act as resting therapy for inspiratory muscles that had reached the threshold fatigue, through the reduction of pressure pleural swings during tidal ventilation and consequently mitigating the inspiratory effort. Given that, the most recent literature supports the notion that NIV might provide sufficient and useful respite to eligible patients until fast-acting procedures as plasma exchanges and other immunomodulating therapies exert their effect [2 , 7] .…”

“…The main question addressed by Di Costanzo et al [1] cannot be fully answered for several reasons. First, the retrospective nature of the study cannot allow definitive conclusions, although the current understanding of MC, including treatment and outcome, up to now is only retrospective [2 , 7 , [9] , [10] , [11] , [12] . Di Costanzo et al [1] should consider that in our study, we reviewed all patients admitted to our Neurological ward falling into the definition of Class V of Myasthenia Gravis Foundation of America, therefore in need of ventilator support by definition [2 , 7] .…”

“…First, the retrospective nature of the study cannot allow definitive conclusions, although the current understanding of MC, including treatment and outcome, up to now is only retrospective [2 , 7 , [9] , [10] , [11] , [12] . Di Costanzo et al [1] should consider that in our study, we reviewed all patients admitted to our Neurological ward falling into the definition of Class V of Myasthenia Gravis Foundation of America, therefore in need of ventilator support by definition [2 , 7] . One the main findings of our study was the low rate of NIV failure; indeed, only 37.7% of MC required endotracheal intubation and MV [2] .…”