Should We Assess Diaphragmatic Function During Mechanical Ventilation Weaning in Guillain–Barré Syndrome and Myasthenia Gravis Patients?

Abstract

Acute respiratory failure is the main reason for the admission of Guillain–Barré syndrome (GBS) and myasthenia gravis (MG) patients to the ICU. About 30% of GBS patients and 10 to 30% of MG patients will require mechanical ventilation (MV) over their disease course [1–3]. Once the disease and eventually its triggering event are treated, time for weaning begins. Liberation from MV, i.e. extubation success, constitutes the final achievement of this process. Outside the scope of neurocritical care unit (NICU), patients are now sorted into four weaning groups [4] (Table 1): the group “no weaning”, made of patients who never experienced any separation attempt; the group 1 (short weaning): the first attempt resulted in a termination of the weaning process within 1 day; the group 2 (difficult weaning): the weaning was completed after more than 1 day but in less than 1 week after the first separation attempt and the group 3 (prolonged weaning): weaning was still not terminated 7 days after the first separation attempt. Even if the original study including 2729 patients did not excluded specifically GBS or MG patients, their proportion was likely to be limited and no study have used this classification in these patients. However, between 26 [5] and 75% [6] of GBS or MG patients are still under MV at day 7 and most authors assume that extubation failure accounts for 30% in those patients [5, 7]. Whereas prolonged MV is associated with an increased risk of ventilator-associated pneumonia, premature liberation is associated with increased risk of extubation failure and increased risk of mortality and morbidity [5, 8]. Hence, determining the optimal timing for extubation is of major importance. Several questions arise when the weaning process begins: (1) which ventilation mode should be preferred to enable the respiratory muscles to both rest and not to waste? [9]; (2) when to start spontaneous breathing trials (SBT)?; (3) should positive pressure support (PSV) or T-piece trials be used for SBT?; (4) which respiratory parameters should be used to predict successful extubation?; and finally (5) is there any place for non-invasive mechanical ventilation (NIV) or high-flow nasal oxygenation to increase extubation success rate? Synchronized intermittent mandatory ventilation is now discouraged since this mode was associated with prolonged weaning [8, 10], and pressure support ventilation (PSV) should be preferred over assisted ventilation when weaning begins [8, 11, 12]. In general ICU, readiness criteria to start SBT and readiness criteria for extubation are widely accepted and should probably at least be applied to NICU patients (Table 1) [8, 11]. In GBS and MG patients, forced vital capacity and maximal inspiratory pressure are frequently added to these minimal criteria (Table 1) [5]. Whereas no difference has been found in SBT duration when ranging from 30 min to 2 h in general ICU [8], most neurointensivists performed “prolonged” SBT in GBS and MG patients going from one to several hours, up to 12–24 h, but this practice is *Correspondence: [email protected] 1 Sorbonne University & Neurological Intensive Care Unit, Department of Neurology, AP-HP.Sorbonne Université, Hôpital Pitié-Salpêtrière, 47-83, Boulevard de l’Hôpital, 75013 Paris, France Full list of author information is available at the end of the article