Extracorporeal Ammonia Clearance for Hyperammonemia in Critically Ill Patients: A Scoping Review

<b><i>Introduction:</i></b> Hyperammonemia is a life-threatening condition. However, clearance of ammonia via extracorporeal treatment has not been systematically evaluated. <b><i>Methods:</i></b> We searched EMBASE and MEDLINE databases. We included all publications reporting ammonia clearance by extracorporeal treatment in adult and pediatric patients with clearance estimated by direct dialysate ammonia measurement or calculated by formula. Two reviewers screened and extracted data independently. <b><i>Results:</i></b> We found 1,770 articles with 312 appropriate for assessment and 28 studies meeting eligibility criteria. Most of the studies were case reports. Hyperammonemia was typically secondary to inborn errors of metabolisms in children and to liver failure in adult patients. Ammonia clearance was most commonly reported during continuous renal replacement therapy (CRRT) and appeared to vary markedly from &#x3c;5 mL/min/m² to &#x3e;250 mL/min/m². When measured during intermittent hemodialysis (IHD), clearance was highest and correlated with blood flow rate (<i>R</i>² = 0.853; <i>p</i> &#x3c; 0.001). When measured during CRRT, ammonia clearance could be substantial and correlated with effluent flow rate (EFR; <i>R</i>² = 0.584; <i>p</i> &#x3c; 0.001). Neither correlated with ammonia reduction. Peritoneal dialysis (PD) achieved minimal clearance, and other extracorporeal techniques were rarely studied. <b><i>Conclusions:</i></b> Extracorporeal ammonia clearance varies widely with sometimes implausible values. Treatment modality, blood flow, and EFR, however, appear to affect such clearance with IHD achieving the highest values, PD achieving minimal values, and CRRT achieving substantial values especially at high EFRs. The role of other techniques remains unclear. These findings can help inform practice and future studies.

Continuous extracorporeal treatments in a dialysis patient with COVID-19

The coronavirus disease 2019 (COVID-19) pandemic is now a major global health threat. More than half a year have passed since the first discovery of severe acute respiratory syndrome coronavirus-2 (SARS-CoV2), no effective treatment has been established especially in intensive care unit. Inflammatory cytokine storm caused by SARS-CoV-2 infection has been reported to play a central role in COVID-19; therefore, treatments for suppressing cytokines, including extracorporeal treatments, are considered to be beneficial. However, until today the efficacy of removing cytokines by extracorporeal treatments in patients with COVID-19 is unclear. Herein, we report our experience with a 66-year-old male patient undergoing maintenance peritoneal dialysis who became critically ill with COVID-19 and underwent several extracorporeal treatment approaches including plasma exchange, direct hemoperfusion using a polymyxin B-immobilized fiber column and continuous hemodiafiltration. Though the patient developed acute respiratory distress syndrome (ARDS) repeatedly and subacute cerebral infarction and finally died for respiratory failure on day 30 after admission, these attempts appeared to dampen the cytokine storm based on the observed decline in serum IL-6 levels and were effective against ARDS and secondary haemophagocytic lymphohistiocytosis. This case suggests the significance of timely initiation of extracorporeal treatment approaches in critically ill patients with COVID-19.

Continuous extracorporeal treatments in a dialysis patient with COVID-19

The coronavirus disease 2019 (COVID-19) pandemic is now a major global health threat. More than half a year have passed since the first discovery of severe acute respiratory syndrome coronavirus-2 (SARS-CoV2), no effective treatment has been established especially in intensive care unit. Inflammatory cytokine storm caused by SARS-CoV-2 infection has been reported to play a central role in COVID-19; therefore, treatments for suppressing cytokines, including extracorporeal treatments, are considered to be beneficial. However, until today the efficacy of removing cytokines by extracorporeal treatments in patients with COVID-19 is unclear. Herein, we report our experience with a 66-year-old male patient undergoing maintenance peritoneal dialysis who became critically ill with COVID-19 and underwent several extracorporeal treatment approaches including plasma exchange, direct hemoperfusion using a polymyxin B-immobilized fiber column and continuous hemodiafiltration. Though the patient developed acute respiratory distress syndrome (ARDS) repeatedly and subacute cerebral infarction and finally died for respiratory failure on day 30 after admission, these attempts appeared to dampen the cytokine storm based on the observed decline in serum IL-6 levels and were effective against ARDS and secondary haemophagocytic lymphohistiocytosis. This case suggests the significance of timely initiation of extracorporeal treatment approaches in critically ill patients with COVID-19.

Continuous extracorporeal treatments in a dialysis patient with COVID-19

The coronavirus disease 2019 (COVID-19) pandemic is now a major global health threat. More than half a year have passed since the first discovery of severe acute respiratory syndrome coronavirus-2 (SARS-CoV2), no effective treatment has been established especially in intensive care unit. Inflammatory cytokine storm caused by SARS-CoV-2 infection has been reported to play a central role in COVID-19; therefore, treatments for suppressing cytokines, including extracorporeal treatments, are considered to be beneficial. However, until today the efficacy of removing cytokines by extracorporeal treatments in patients with COVID-19 is unclear. We herein report our experience with a 66-year-old male patient undergoing maintenance peritoneal dialysis who became critically ill with COVID-19 and underwent several extracorporeal treatment approaches including plasma exchange, direct hemoperfusion using a polymyxin B-immobilized fiber column and continuous hemodiafiltration. Though the patient developed acute respiratory distress syndrome (ARDS) repeatedly and subacute cerebral infarction and finally died for respiratory failure on day 30 after admission, these attempts appeared to somewhat dampen the cytokine storm based on the observed decline in serum IL-6 levels and were effective against ARDS and secondary haemophagocytic lymphohistiocytosis. This case suggests the significance of timely initiation of extracorporeal treatment approaches in critical ill patients with COVID-19.