Noninvasive Ventilation in Myasthenia Gravis

Clinical features and outcomes of patients with myasthenia gravis admitted to an intensive care unit: A 20-year retrospective study

Background

There are limited data on the clinical characteristics and outcomes of patients with myasthenia gravis (MG) admitted to the intensive care unit (ICU) at Charlotte Maxeke Johannesburg Academic Hospital (CMJAH).

Objectives

The aim was to study the clinical characteristics and outcomes of patients with MG admitted to the CMJAH over two decades.

Methods

A retrospective study was undertaken of patients with MG admitted to the multidisciplinary ICU of CMJAH over a 20-year period, from 1998 to 2017. Demographic data, clinical features, management and outcomes of patients were assessed and reviewed from the case records.

Results

Thirty-four patients with MG were admitted to the ICU during this period: 24 female and 10 male. The mean age ± SD was 37.4 ± 13.0 years, with a range of 16 - 66 years. Four patients were human immunodeficiency virus (HIV)-positive. The mean length of stay (LOS) in ICU was 10.6 ± 20.1 days, ranging from 1 to 115 days. Two patients were diagnosed with MG in the ICU after failure to wean from the ventilator. Overall, 22 patients were intubated and ventilated on admission. Morbidities included self-extubation, aspiration pneumonia and iatrogenic pneumothorax. History of thymectomy was present in 12 patients. The treatments received for MG included pyridostigmine (73.5%), corticosteroids (55.9%), azathioprine (35.3%), plasmapheresis (26.5%) and intravenous immunoglobulin (8.8%). The overall mortality in the ICU was 5.9%.

Conclusion

MG is a serious disorder with considerable morbidity and mortality. It is, however, a potentially manageable disease, provided that appropriate ICU resources are available.

Contributions of the study

This study provides further insight into the characteristics and outcomes of myasthenia gravis patients in ICU, within a South African context.

Myasthenia gravis, respiratory function, and respiratory tract disease

Myasthenia gravis (MG) is characterized by muscle weakness caused by autoantibodies that bind to the postsynaptic membrane at the neuromuscular junction and impair acetylcholine receptor function. Weakness of respiratory muscles represents the most severe MG manifestation, and 10-15% of all patients experience an MG crisis with the need of mechanical ventilatory support at least once in their life. MG patients with respiratory muscle weakness need active immunosuppressive drug treatment long term, and they need regular specialist follow-up. Comorbidities affecting respiratory function need attention and optimal treatment. Respiratory tract infections can lead to MG exacerbations and precipitate an MG crisis. Intravenous immunoglobulin and plasma exchange are the core treatments for severe MG exacerbations. High-dose corticosteroids, complement inhibitors, and FcRn blockers represent fast-acting treatments that are effective in most MG patients. Neonatal myasthenia is a transient condition with muscle weakness in the newborn caused by mother's muscle antibodies. In rare cases, treatment of respiratory muscle weakness in the baby is required.

Rituximab in Myasthenia Gravis- Experience from a Low- and Middle-Income Country (LMIC) Setting

BACKGROUND

Myasthenia gravis (MG) is an immune-mediated disorder of the neuromuscular junction. About 10% are refractory to immunosuppressive therapy.

AIMS

To analyze the response of patients with generalized MG to rituximab.

METHODS AND MATERIALS

A retrospective review of patients with MG who received rituximab was carried out (n = 13, M:F = 6:7, mean age: 44.84 ± 15.73 years). Myasthenia Gravis Foundation of America (MGFA), MGFA post-intervention status (MGFA-PIS), and Myasthenia Gravis Status and Treatment Intensity (MGSTI) were assessed before and after rituximab.

RESULTS

The duration of MG was 104.07 ± 92.25 months. Before rituximab, the MGFA was IIA/IIB/IIIA/IIIB/IVB/V in 1/1/2/6/2/1 patients and MGSTI was four in eight patients and six in three patients. The mean duration of follow up was 20.92 ± 14.06 months (range, 4 to 42 months). Dose reduction or discontinuation of cholinesterase inhibitors could be achieved 12 patients. Complete stable remission (CSR) and pharmacologic remission (PR) were achieved in one and four patients respectively and five patients had minimal manifestations. Most patients attained level 0, 1 or 2 MGSTI at last follow up. No rituximab infusion-related adverse events were noted. Three patients had exacerbation of MG between one to five weeks after rituximab administration. Three patients died, one each due to a cardiac event unrelated to MG or treatment, complications related to myasthenic crisis, and coronavirus disease.

CONCLUSIONS

Rituximab was effective in bringing about remission in MG and can be considered as a first-line agent. However, it has to be administered under close supervision as some patients develop exacerbation of MG akin to steroid-induced worsening.

Cardiac disorders worsen the final outcome in myasthenic crisis undergoing non-invasive mechanical ventilation: a retrospective 20-year study from a single center

The study was performed to evaluate the impact of cardiological disorders on the outcome of myasthenic crisis (MC) requiring ventilation. The study includes 90 cases admitted to the Neurology Unit of Modena, Italy (January 2000 - September 2020). All patients were eligible for a non-invasive ventilation (NIV) trial. We analyzed the effect of cardiac comorbidities on the outcomes, which were the need of invasive ventilation, the risk tracheostomy for weaning failure and the duration of intensive care unit (ICU) stay Females were 58.9% and males 41.1%. Median age at diagnosis was 59 and at MC was 65. Patients were classified as early (EOMG) or late (LOMG), 34.4 and 65.6% respectively, according to age above or below 50; 85% of patients were anti- AChR antibody positive. Hypertension and cardiac diseases occurred at the diagnosis in 61 and 44.4%, respectively. Invasive mechanical ventilation (MV) was needed in 34% of cases. Nine subjects (10%) underwent tracheostomy because of weaning failure. Independent predictors of NIV failure were atrial fibrillation (AF), either parossistic or persistent (OR 3.05, p < 0.01), hypertensive cardiopathy (HHD) (OR 2.52, p < 0.01) and ischaemic heart disease (IHD) (OR 3.08, p < 0.01). Hypertension (HT) had no statistical effect on the outcomes. HHD was a predictor of weaning failure (OR 4.01, p = 0.017). Our study shows that HHD, AF and IHD increase the risk of NIV failure in MC receiving ventilation.

Noninvasive and invasive mechanical ventilation for neurologic disorders

Patients with acute neurologic injuries frequently require mechanical ventilation due to diminished airway protective reflexes, cardiopulmonary failure secondary to neurologic insults, or to facilitate gas exchange to precise targets. Mechanical ventilation enables tight control of oxygenation and carbon dioxide levels, enabling clinicians to modulate cerebral hemodynamics and intracranial pressure with the goal of minimizing secondary brain injury. In patients with acute spinal cord injuries, neuromuscular conditions, or diseases of the peripheral nerve, mechanical ventilation enables respiratory support under conditions of impending or established respiratory failure. Noninvasive ventilatory approaches may be carefully considered for certain disease conditions, including myasthenia gravis and amyotrophic lateral sclerosis, but may be inappropriate in patients with Guillain-Barré syndrome or when relevant contra-indications exist. With regard to discontinuing mechanical ventilation, considerable uncertainty persists about the best approach to wean patients, how to identify patients ready for extubation, and when to consider primary tracheostomy. Recent consensus guidelines highlight these and other knowledge gaps that are the focus of active research efforts. This chapter outlines important general principles to consider when initiating, titrating, and discontinuing mechanical ventilation in patients with acute neurologic injuries. Important disease-specific considerations are also reviewed where appropriate.