Dr Deepak Govil, Director, Institute of Critical Care and Anaesthesiology, Medanta details how COVID-19 infections have been leading to abnormalities in kidneys and why American Society of Nephrology recommends CRRT to patients not responding to medical management
The COVID-19 pandemic has caused critical challenges to the public health, research and communities at large. Its infectious wave has affected the people health-wise in myriad ways, bringing along many health disorders wherein kidney deformities stand as a frontrunner. A report issued by the International Society of Nephrology (ISN) reveals that at least 20 per cent of the people who have been infected with COVID-19 (Coronavirus) infection have developed abnormalities in kidneys.
Among COVID-19 infected patients who develop severe infection and require hospitalisation, kidney abnormalities are seen in 25-50 per cent subjects, manifested as increased excretion of protein and red blood cells in urine and close to 15 per cent develop Acute Kidney Injury. 
In COVID-19, Acute Kidney Injury (AKI) seems to be the next emerging healthcare and resource issue after the devastating respiratory consequences brought in by the pandemic. Clinicians are devising creative solutions and workarounds but are also cautioning that AKI is driving up patient deaths and lingering sequela of the COVID-19 pandemic. 
As per the recommendation of the American Society of Nephrology (ASN), COVID-19 patients who develop AKI and life-threatening complications, and do not respond to medical management, should be considered for Renal Replacement Therapy (RRT). Any modality of RRT may be used to manage AKI; however, CRRT is the preferred modality in haemodynamically unstable patients. CRRT is a term used for a collection of acute dialysis techniques that can support the patients for 24 hours in a day. 
In the current scenario, the management of AKI due to COVID-19 infection hinges on Renal Replacement Therapy, given the absence of effective antiviral therapy. Small proportion of these patients require acute or urgent dialysis, where Continuous Renal Replacement Therapy (CRRT) may be used as it can support these patients for 24 hours in a day, especially to the critically ill patients suffering from AKI. 
As per the recommendation from ASN, the CRRT devices can be used to perform PIRRT or intermittent dialysis which can be applied at a higher dose for shorter periods, which would allow the same device to be used on multiple patients in a day without compromising the renal toxin clearance. Moreover the severity of COVID-19 has to be linked with increasing levels of circulating Cytokines or mediators of inflammation which can also be removed by some modalities of CRRT.
Challenges in the management of AKI
In the current situation created by COVID-19 pandemic, the availability of the workforce may be challenging. The workforce can be preserved and / or protected by decreasing dialysis nurse exposure to patients with COVID-19. Preferentially, utilising CRRT for patients in the intensive care unit (ICU) that are infected with COVID-19 may help decrease the number of nurses being exposed to the illness and thereby reducing the risk of contamination. 
In addition, extension tubing can be used so that the CRRT machine can be run outside the patient’s room, decreasing the need for the ICU nurse to enter the room frequently. However, this presents with a new set of challenges where patients are likely to become hypothermic with a longer extracorporeal circuit. So warming strategies may become imperative including integrated warming circuits bed-based warming tools and warming blood or CRRT fluids. 
The increasing number of AKI patients due to COVID-19 infection has posed a challenge before resource management. Therefore, it becomes important to use the available resources judiciously or to even conserve it. We can conserve the resources in the following ways:
- For intermittent haemodialysis, consider the shortest duration that achieves
- metabolic and volume control and minimise 1:1 nurse time in the room.
- Delay RRT if possible in patients whose COVID tests are pending, which can conserve PPE.
- Use high-dose diuretics in AKI patients, with binders to lower potassium.
- Decrease flow rates in CRRT after metabolic control has been achieved to save fluids.
- Cross-train nephrologists and additional nurses if necessary to help set up or monitor patients undergoing dialysis. 
To curb the rising incidence of AKI due to COVID-19 infection, the early initiation of Renal Replacement Therapy (RRT) and sequential extracorporeal therapies as a means to provide adequate organ support and to prevent the progression of COVID-19 severity should be evaluated.
 ISN Guidelines 2020, https://www.theisn.org/covid-19. Last accessed on 25th March 2020
 Chu KH, Tsang WK, Tang CS et al. Acute renal impairment in coronavirus associated severe acute respiratory syndrome. Kidney Int. 2005 Feb; 67(2):698-705.
 Arabi YM, Arifi AA, Balkhy HH, et al. Clinical course and outcomes of critically ill patients with Middle East respiratory syndrome coronavirus infection. Ann Intern Med. 2014 Mar 18; 160(6):389-97.
 Ghani RA, Zainudin S, Ctkong N, et al. Serum IL-6 and IL-1-ra with sequential organ failure assessment scores in septic patients receiving high-volume hemofiltration and continuous venovenous haemofiltration. Nephrology (Carlton).2006 Oct; 11(5):386-393.
 Yi Yang*, Jia Shi*, Shuwang Ge et al. Effect of continuous renal replacement therapy on all cause mortality in COVID-19 patients undergoing invasive mechanical ventilation: a retrospective cohort study. https://doi.org/10.1101/2020.03.16.20036780