Myasthenia Gravis as a Cause of Failed Extubation Diagnosed by Diaphragmatic Ultrasound

Myasthenia Gravis (MG) is an autoimmune disease of the neuromuscular junction which results in generalised weakness. Presentation varies and can often be delayed as the course is waxing and waning. We report the case of an elderly patient who was admitted with severe cholangitis. The patient required a general anaesthesia with intubation for a planned endoscopic retrograde cholangiopancreatogram (ERCP). She was extubated a few hours after the procedure in the intensive care unit (ICU). However, a few hours later, she required re-intubation for tiring out and a raised paCO₂ level. When assessed by a diaphragmatic ultrasound, she was found to have severe weakness, and a provisional diagnosis of MG was made after other causes, such as sepsis, were ruled out. As a fast, inexpensive and non-invasive test, ultrasound offers many advantages and can also be used serially to assess recovery of a paralyzed diaphragm as well to achieve successful liberation from mechanical ventilation.