Case Presentation: A 79-year-old male with vasculopathy, hypertension, diastolic heart failure, and dialysis-dependent end stage renal disease presented after having hypotensive syncopal episodes during initiation of his last 3 outpatient dialysis sessions. Upon dialysis cessation, he quickly awakened fully oriented with a normal hemodynamics. On arrival, physical exam findings were unrevealing, as were a subsequent syncopal work-up with cardiac echo, EKG, head CT, carotid ultrasound, and orthostatic vitals. Assuming insufficient compensatory cardiac output due to beta blocker use, repeat dialysis (while holding metoprolol) was attempted, yet resulted in another similar syncopal episode. Repeat CBC showed a WBC count of 38.9 K/uL with an absolute eosinophil count of 23.5 K/uL. A tryptase level was also significantly elevated, thus suggesting a severe allergic process associated with dialysis. Consequently, the patient received famotidine, cetirizine, and diphenhydramine prior to another dialysis attempt the following day. He syncopized again, and subsequently developed pulmonary edema and hypoxia from accumulating fluid. Although a bone marrow biopsy was done to assess for possible primary hematologic malignancy (ultimately normal), a reactive-type process was still believed to be responsible. Thus, pre-dialysis exposure with prednisone was initiated, which significantly lowered his eosinophil count, and resulted in successful removal of 2.5 L of fluid with a stable hemodynamic response. Following on this empiric evidence of a dialysis-related allergy, additional workup demonstrated high levels of serum IgE to ethylene oxide (EO), a gas widely used for sterilization of dialysis equipment. The patient was successfully transitioned from prednisone to omalizumab anti-IgE therapy for longer term dialysis success.

Discussion: Dialysis-related syncopal events can have varied causes – but in this case, the temporal relationship of symptoms to dialysis initiation, as well as eosinophilia, elevated tryptase, and high levels of anti-EO IgE antibodies rightfully establish an EO allergy as the culprit. Eosinophilia occurs in roughly 5% of dialysis patients and is likely due to a subclinical allergy to dialysis circuit components.1 This patient had slowly worsening eosinophilia over a 4-year course, heralding the dramatic clinical presentation we observed. Periodic monitoring of eosinophil levels may be useful in differentiating an allergic response as a potential cause of intradialytic hypotension/syncope. For EO-related dialysis allergies, short term treatment with prednisone is successful in the treatment of intradialytic hypotension, but long-term treatment is presently not well established.2

Conclusions: Intradialytic hypotension with syncope has a broad differential, including hyper-eosinophilia with ethylene oxide allergy. Short-term treatment with prednisone is successful, and long-term treatment with omalizumab may be successful in lessening levels of IgE to ethylene oxide.