Therapeutic plasma exchange (TPE) may be useful in patients with myasthenia gravis (MG). Still, serious adverse events must be minimized, according to a study recently published in the American Journal of Case Reports.

“[Unfractionated heparin] dose adjustment, frequent assessment of [activated partial thromboplastin time (aPTT)] levels, and close monitoring of bleeding are essential during TPE treatment to minimize any serious bleeding complications,” the authors wrote.

This case report describes a 78-year-old female previously diagnosed with MG who underwent a thymectomy complicated by bleeding secondary to superior vena cava and innominate vein injury, as well as phrenic nerve injury. After receiving mechanical ventilation for 6 days in the intensive care unit due to respiratory failure, she developed a provoked deep venous thrombosis in the left upper limb. 

Read more about MG therapies

Despite treatment with 60 mg of pyridostigmine bromide 4 times a day, 20 mg of prednisolone daily, 100 mg of azathioprine daily, and unfractionated heparin at a rate of 1100 U per hour, the patient did not improve. The healthcare team then ordered 5 sessions of TPE every other day via the femoral vein.

Each TPE session lasted 65 to 150 minutes, and 5% albumin was used as the replacement fluid, with about 3 liters exchanged each procedure. Interestingly, with the same dose of unfractionated heparin, the aPTT increased to 96.4 seconds from previous measures of 50 to 80 seconds.

The change was evident 4 hours after the first TPE occurred, and after 7 hours, the aPTT returned to the desired range at 47.8 seconds. During the patient’s second procedure, the aPTT was more than 170 seconds, decreasing back to 48.4 seconds after 10 hours.

These shifts occurred throughout all TPE sessions, and the patient remained without evidence of major bleeding events. Due to clinical improvement, the patient was discharged and instructed to take 5 mg of oral apixaban daily. 

At the 3-month follow-up visit, she reported no signs of bleeding and an ultrasound confirmed the absence of clotting events. Hence, her physicians discontinued the apixaban. At the 6-month follow-up visit, she did not report bleeding or clotting events. 

Because TPE is a beneficial alternative treatment for patients with MG, its use should be a feasible option, especially in cases without a clear medical treatment response. Regardless, due to its ability to temporarily deplete coagulation factors, this treatment should be administered under careful monitoring.

“In addition, this case highlights the importance of aPTT measurement with [unfractionated heparin] before and after each TPE session, which can prevent the supratherapeutic effect of [unfractionated heparin] and fatal consequences, such as bleeding,” the authors concluded.

Reference

Alshehri SD, Al Sulaiman K, Aljuhani O, et al. Therapeutic plasma exchange and supratherapeutic levels of unfractionated heparin in the management of critically ill patient with myasthenia gravis: a case report. Am J Case Rep. Published online November 29, 2022. doi:10.12659/AJCR.937617