Severe metabolic acidosis on CVVHD or CVVHDF with Citrate Anticoagulation in critically ill patients with COVID-19: A case-series

ABSTRACT

Background: Acute kidney injury (AKI) is frequent in critical ill patients and around 20% of patients admitted to intensive care unit (ICU) require continuous renal replacement therapy (CRRT). In our center, during the first pandemic wave, we observed severe metabolic acidosis associated with a worsening of respiratory function in our COVID-19 patients receiving continuous hemodialysis (CVVHD) and hemodiafiltration (CVVHDF). The aim of the study is to assess the association between arterial blood gas (ABG) data and haemodynamic parameters in COVID-19 patients receiving CVVHD or CVVHDF. Regional citrate anticoagulation was applied for all CRRT treatments. Our hypothesis was that hypoperfused patients could face a reduced metabolic and hepatic activity, making them unable to metabolize the citrate to bicarbonate, worsening their acidosis instead of correcting it. Method(s) This is a retrospective, observational study. It includes 10 COVID-19 patients hospitalized at the ICU of the Bufalini Hospital of Cesena (Italy) from the 11th of March to 26th of April 2020 and treated with CRRT. Overall, 28 CRRT treatments were analysed and patients were divided in two groups 1) Hypotensive Group (MAP < 70 mmHg);2) Non Hypotensive Group (MAP> 70 mmHg). ABG and MAP data were recorded pre and post-treatment. Patients with severe or worsening metabolic acidosis (pH < 7.3) pre-CRRT were defined as "non-adjusters". Result(s) A number of 9 (50%) hypotensive patients were able to correct their acidotic status, while (70%) of normotensive patients were able to improve their pH. The number of patients and treatments is too low to calculate p-value. In 28 CRRTs performed, 16 (57%) corrected their pH. (57%), while 12 (43%) severe acidosis were refractory to the treatment. Eighteen patients (64%) presented hypotension, 10 (36%) presented with normal pressure levels (MAP>65mmHg). In hypotensive patients,mean pre-CRRT pH value was 7,31 (+/-0,07) with BE mean value-3,4 (+/-2,7);in non-hypotensive group the pre- CRRT mean pH value was 7,33 (+/-0,01) with BE mean value-2,67 (+/-4,7). Mean lactate levels in the hypotensive group were 1,26 (+/-0,6), in the non hypotensive group the mean value was 1,6 (+/-0,74). Conclusion(s) In COVID19 patients, the impairement of organ perfusion might reduce the ability of the liver to metabolise citrate, worsening metabolic acidosis. The use of CRRT with lactate-buffered fluids in some cases might not be helpful, leading to further increases in lactate levels.