Methemoglobinemia in Hemodialysis Patients due to Acute Chlorine Intoxication: A Case Series Calling Attention on an Old Problem

INTRODUCTION

Hemodialysis uses municipal water that must be strictly purified and sterilized to be used for that procedure. Large amounts of decontaminants are often used, such as chlorine, and if these compounds are not subsequently removed they can be transferred to the blood of patients causing complications including methemoglobinemia.

METHODS

In this case series study, dialysis patients in one unit were evaluated. We reviewed clinical characteristics and laboratory findings obtained on the day when the water supply was disinfected with chlorine, with the aim to quantify methemoglobin concentrations. Our objective was to characterize the clinical presentation and management of patients who presented with methemoglobinemia on a specific index day. We also reviewed reported cases in the literature regarding this underreported complication.

RESULTS

Eight patients who presented with chlorine intoxication were evaluated. The methemoglobin concentrations were between 1.3% and 7.9% (reference value 0-1%). We believe this to be caused by water containing 0.78 mg/L of total chlorine. Seven patients presented with cyanosis, 4 with dizziness, 6 with dark brown blood, 4 with dyspnea, and 4 with headache and hemolytic anemia. Subjects were treated with supplemental oxygen, methylene blue, intravenous vitamin C, blood transfusions, and increased doses of erythropoietin. No patient died, and all continued with their usual hemodialysis sessions.

CONCLUSION

Acute chlorine intoxication transferred by the water used during hemodialysis sessions can present with methemoglobinemia accompanied by cyanosis, oxygen desaturation, and hemolytic anemia. Chlorine levels should be carefully monitored in the water used for hemodialysis treatment.

Seraph-100 Hemoperfusion in SARS-CoV-2-Infected Patients Early in Critical Illness: A Case Series

There is an urgent need for therapeutic interventions to alter the course of critically ill coronavirus disease 2019 (CO­VID-19) patients. We report our experience with the Seraph-100 Microbind Affinity Blood Filter (Seraph-100) in 4 patients with COVID-19 early in the course of their critical respiratory illnesses. Patients were diagnosed with COVID-19 and were admitted to intensive care with worsening respiratory failure but did not require dialysis or vasopressors. Patients had to have a PaO₂ to FiO₂ (P/F ratio) <150 to qualify for hemoperfusion therapy. All patients received standard medical therapy including oral vitamins C and D and zinc in addition to intravenous dexamethasone and remdesivir. Patients received a single 5- to 7-h session with Seraph-100 on a conventional dialysis machine (Fresenius 2008T) via a nontunneled central venous dialysis catheter with a goal of processing at least 100 L of blood. Patients received weight-based subcutaneous enoxaparin anticoagulation, as well as systemic intravenous heparin (70 units/kg), just prior to hemofiltration. Treatment with Seraph-100 hemoperfusion was well tolerated, and all patients were able to finish their prescribed therapy. All patients treated with Seraph-100 survived to be discharged from the hospital. Well-designed clinical trials are needed to determine the overall safety and efficacy of the Seraph-100 Microbind Affinity Blood Filter in COVID-19 patients.

Percutaneous balloon cryoplasty: A new therapy for rapidly recurrent anastomotic venous stenoses of hemodialysis grafts?

Vascular access dysfunction is a major source of morbidity for end-stage renal disease patients on hemodialysis. The arteriovenous graft is a common access type for many of these patients. Frequent stenosis formation and thrombosis complicate this form of access. Patients may have a rapidly forming and recurrent venous stenosis at the graft-vein anastomosis that has been seen in both animal models and end-stage renal disease patients to be the result of neointimal hyperplasia. This venous lesion is particularly resistant and sometimes intractable to conventional angioplasty. As a result, new therapies have been developed to reduce the formation and/or recurrence of neointimal hyperplasia. These include special cutting balloons, drug-eluting stents, and endovascular brachytherapy. The authors present the cases of 5 patients with rapidly recurrent venous lesions at the graft-vein anastomosis that derived benefit from angioplasty with the cryoballoon. The time to stenosis or thrombosis in the arteriovenous grafts was increased from a mean of 3 weeks to more than 16 weeks with this technology. Cryotherapy with the cryoballoon (cryoplasty) may represent a useful therapy for patients with intractable stenoses at or near the venous anastomosis of arteriovenous grafts.