COVID-19 and acute kidney injury – do you know how to identify patients at risk?

AKI is linked to COVID-19, and the pandemic has affected both its incidence and demographics

AKI is linked to COVID-19, and the pandemic has affected both its incidence and demographics

  • As the second wave of COVID-19 comes to an end, long-term effects on both kidney function and kidney care services are coming clearer
  • Rates of acute kidney injury (AKI) have increased, including among younger people and those not typically at risk
  • What nurses in every setting need to know about symptoms of renal failure, as early intervention can save lives
Illustration showing acute kidney injury
Picture: iStock

As the long-term effects of COVID-19 on patients and services continue to be assessed, nurses working in renal care are concerned about a potential increase in cases of kidney damage caused by the virus.

The kidneys are among the organs that may be affected by COVID-19. During the first wave, the National Institute for Health and Care Excellence (NICE) published a guideline warning that acute kidney injury (AKI) was more common in people with COVID-19.

Managing COVID-19 while protecting kidney function

AKI is a sudden drop in kidney function, over a few hours to a few days. It commonly occurs with an episode of acute illness and is more likely if the illness is severe, or if an individual is at greater risk of the condition. Its severity can range from a minor loss of kidney function to complete kidney failure. It is essential it is identified and treated quickly, as AKI is associated with about 100,000 deaths a year in the UK, according to Kidney Care UK.

‘Treatments for COVID-19 and pre-existing conditions may increase the risk of AKI, and fever and increased respiratory rate increase insensible fluid loss’

Updated NICE guidance on managing COVID-19 in hospitals lists AKI as one of the acute complications. The guidance says that for people with COVID-19, maintaining optimal fluid status (euvolaemia) is difficult but critical to reducing the incidence of AKI.

Treatments for COVID-19, such as diuretic therapy and non-invasive ventilation, and pre-existing conditions may increase the risk of AKI, and fever and a raised respiratory rate increase insensible fluid loss.

This highlights the complexity of managing unwell patients with the virus while trying to protect their kidney function.

Causes of acute kidney injury

Most cases of acute kidney injury (AKI) are due to reduced blood flow to the kidneys, usually in a patient already unwell with another health condition.

This reduced blood flow could be caused by:

  • Low blood volume after bleeding, excessive vomiting or diarrhoea, or severe dehydration
  • The heart pumping out less blood than normal as a result of heart failure, liver failure or sepsis
  • Problems with the blood vessels, such as vasculitis – an autoimmune disease that causes inflammation and narrowing of blood vessels
  • Certain medications that can affect the blood supply to the kidney
  • Problems with the kidney itself, such as glomerulonephritis. This may be caused by a reaction to some drugs, infections or the liquid dye used in some types of X-rays
  • A blockage affecting the drainage of the kidneys, such as an enlarged prostate, a tumour in the pelvic area, such as an ovarian or bladder tumour, or kidney stones

Source: NHS: Acute Kidney Injury

Disruptions to kidney services

During the first wave, hospitals saw high rates of AKI. Critical care units started to run out of fluid for dialysis machines, and NHS England had to issue new guidance on conserving supplies.

Almost one in three (29%) of those severely affected by COVID-19 needed dialysis as a result of AKI.

For those with moderate to advanced (stage 3+) chronic kidney disease, the risk of becoming unwell with COVID-19 was increased, according to guidance.

Meanwhile kidney services, including dialysis and transplant, were disrupted by the pandemic, as the NHS focused on treating the critically ill.

Higher risk of death for those with COVID-19 and AKI

University Hospital Southampton AKI lead Becky Bonfield says she and her colleagues have seen an increase in the number and severity of AKI cases. ‘Not only have we seen more patients, but they are more unwell and more likely to die,’ she says.

In a study published in Nephrology, a third (34%) of those admitted to University Hospital Southampton with COVID-19 in the first wave had an AKI while they were admitted.

Having an AKI at the same time as COVID-19 meant a much higher risk of death, with half of patients who had an AKI dying, compared with 21% who did not.

What has changed since the start of the pandemic?

Ms Bonfield suggests many people were affected by AKI in the second wave, as rates of COVID-19 were high, but suspects that a greater proportion will have survived compared with the first wave, as understanding of how to care for people with COVID-19 has improved.

With increased rates of AKI during the pandemic, people have experienced renal problems who otherwise would not have done so.

Ms Bonfield has seen the follow-up clinic for those who have had an AKI in hospital getting busier, and the demographic of patients shifting.

‘Generally, the people visiting our clinic have AKI risk factors, so they are over 65, with pre-existing conditions such as heart disease and diabetes,’ she says. ‘We would see some younger patients, but they were few and far between.

‘Now we have much younger people, in their twenties, thirties and forties, who have had acute AKI and are not getting back to their normal renal baseline.’

Problems when kidney function starts to decline

Ms Bonfield fears the COVID-19 pandemic could have stored up invisible kidney problems that will gradually reveal themselves.

Those who have had an AKI are at higher risk of having it again in the future, and of developing chronic kidney disease, which is when kidney function starts to decline.

She has seen patients who have had COVID-19 but at that time didn’t need intensive care or support for their kidneys, but who later presented to hospital with the ongoing effects of long-COVID and AKI.

Some patients with AKI on these subsequent admissions require intensive care therapies to support their kidney function, she says. Many were previously well and have no significant underlying health conditions.

‘Are we going to have a cohort of people in 20 years’ time who need dialysis or transplants? These are patients who almost certainly wouldn’t have had renal problems if they hadn’t had COVID-19’

Becky Bonfield, AKI lead, University Hospital Southampton

‘These patients will need their renal function checking regularly for the next two years, and maybe lifelong,’ she says.

‘We are seeing a younger demographic that have had a severe AKI, and my worry is if their baseline doesn’t get back to normal they have a long life ahead of them for their kidney function to deteriorate. Are we going to have a cohort of people in 20 years’ time who need dialysis or transplants? These are patients who almost certainly wouldn’t have had renal problems if they hadn’t had COVID-19.’

Signs of declining kidney function

Becky Bonfield, AKI lead, University Hospital Southampton
Nurses need to be alert to signs of declining kidney function, says Becky Bonfield

Nurses in primary care and elsewhere need to be alert to signs that kidney function could have declined or be declining, says Ms Bonfield.

Kidney decline often has few symptoms initially, but can be picked up via blood tests through increased levels of creatinine, a waste product removed by the kidneys.

‘Everyone has a different creatinine baseline, which is affected by factors including size, age and gender,’ Ms Bonfield says.

‘When a nurse is looking at a blood test result they shouldn’t be thinking about what is ‘normal’, as this is a wide standard that won’t say much about this individual. They need to be thinking about what is normal for this patient. Look back at older blood tests to see if this creatinine level looks about the same, or if it is increasing.’

If there are concerns about a patient’s renal function deteriorating, referral to a GP is warranted to initiate assessment of the cause, Ms Bonfield says. The GP can then refer to renal services as required.

Those at high risk of developing AKI need to know when to seek help. This can include if they are vomiting or have diarrhoea, which can cause dehydration.

‘Early intervention saves lives with AKI, we don’t want patients staying at home and not seeking medical care,' Ms Bonfield says.

Psychological support for renal patients

For patients who have been in critical care and are receiving renal treatment, it can be a difficult and overwhelming experience.

Cardiff and Vale University Health Board interim director of nursing for specialist services Claire Main says many of the patients who have had COVID-19 and are now coming for renal care are distressed by what they have been through.

‘They have had a difficult journey, they have been acutely unwell and in critical care, and some have ended up on dialysis and with kidney failure,’ says Ms Main, who has worked in critical care during the pandemic.

‘We are looking at the psychological and follow-up support that patients need.’

Restoring kidney care services

Some kidney care services were disrupted during the pandemic as a result of the redeployment of specialist renal nurses, but these staff are now returning to their previous posts, says Association of Nephrology Nurses UK president and East Kent Hospitals University NHS Foundation Trust consultant nurse in kidney care Karen Jenkins.

Transplant surgery stopped in many centres during the first wave. This in turn affected dialysis provision, with an increased need for dialysis among those patients waiting for a transplant, according to a survey of renal departments published in September 2020.

For nurses in any setting, it’s vital to ‘think kidney’ as patients and services emerge from the second wave, says Ms Jenkins. ‘Recognise patients at risk of AKI, such as changes in body fluid status, sepsis, reduction in urine output. Patient monitoring and early recognition of symptoms of AKI can prevent the need for renal replacement therapy.’

Further information

COVID-19 rapid guideline: managing COVID-19 (National Institute for Health and Care Excellence)