Experts explain Covid-19’s relationship with kidneys


As the pandemic of the new coronavirus progressed, new symptoms entered the health team’s radar. At first, the most common were fever, runny nose, cough and shortness of breath, according to the World Health Organization (WHO). Time passed and the list extended, with reports of patients who had diarrhea, vomiting, loss of smell and taste, sore throats and headaches. Around the world, studies and medical reports pointed to complications related to Covid-19, such as Stroke, Heart and Urinary Diseases and, above all, acute kidney injury, which is a rapid decrease in the ability of the kidneys to filter the metabolic waste from the blood.

According to Luiz Guilherme de Almeida, nephrologist and coordinator of the Intensive Care Center (CTI) Covid-19 of the Hospital da Mulher Dr.ª Nise da Silveira (HM), the kidneys are complex organs, of enormous importance and diverse functions, being responsible for the elimination of toxic waste produced by the human body, such as urea and uric acid, in addition to other toxins. “The kidneys have the function of filtering, cleaning or purifying. They control the volume of fluids, so any excess water in the body is eliminated through the urine; is the so-called diuretic effect. The kidneys also exercise control over the salts of our body, eliminating their excesses or saving them in needy situations. From the control of volume (liquids) and salts, they have a great influence on the blood and venous pressure of our organism. They produce and secrete hormones, such as erythropoietin (which helps in blood production), vitamin D (which acts on calcium absorption) and renin (which controls blood pressure) ”, he explains.

The HM specialist points out that acute kidney injury can trigger three causes: pre-renal, renal and post-renal. The patient who enters a semi-intensive care unit or intensive care unit (ICU) bed ends up dehydrating excessively, either due to fever or mechanical ventilation. “The blood flow reaches the kidneys more weakly, damaging the renal structure. Mechanical ventilation applied to Covid-19, with high internal pressures, decreased venous return. It is as if the lung, because it is so inflated, reduces its effectiveness in draining veins and arteries in irrigating and draining blood to the kidneys. This increase in pulmonary pressure decreases heart pressure. Therefore, the heart needs to be well and, with the appropriate strength to overcome this aggression and pump blood to the kidneys and other organs. The treatment of Covid-19 damages the heart muscle, which ends up causing damage to the kidneys, due to the inefficiency of this pump, which is often irreversible ”, he explains.

He also shows that, in prerenal aggression, the new coronavirus can lead to a direct involvement in the heart muscle, myocarditis, which causes inflammation of the muscle tissue of the heart (myocardium), causing the death of the tissue. “With the heart not working properly, blood flow does not reach the kidneys effectively and, therefore, glomerular filtration drops. As if that were not enough, inflammatory factors paralyze the kidney’s molecular structures, as in any sepsis. It is as if they went into hibernation ”, details the HM nephrologist.

According to Luiz Guilherme Almeida, patients with chronic kidney problems are less severe if they contract Covid-19. “What we thought right at the beginning of the pandemic fell to the ground that they would be the most affected by the new coronavirus. What the experts suspect is that they are less severe due to receiving anticoagulants during dialysis and three-weekly medical attention ”, he says.

Regarding the post-renal phase, the nephrologist explains that the bedridden patient may have an obstruction in the urinary tract, as many of them need a probe, which can cause a urinary tract infection. Greater care is needed in this case. The coordinator of the CTI Covid-19 of the HM states that, since the beginning of the pandemic, nephrologists have considered chronic kidney patients as a risk group for contagion, since they are patients who appear three times a week in a hospital or in a satellite clinic to submit to the dialysis process.

“They are patients undergoing dialysis in hospital units, which are environments with a high probability of contamination by exposure, due to the various bacteria and viruses present in these places. Often, the impacts can be irreversible, so care must be doubled. So, just for that reason, it is enough to consider them as a group at risk of contagion of the new coronavirus, because these individuals are the most exposed to the environment of a hospital almost daily ”, guarantees the HM doctor.

Luiz Guilherme Almeida adds that the main etiological cause of chronic kidney disease is diabetes, followed by arterial hypertension. In underdeveloped countries, on the other hand, the rate is high in patients affected by glomerulonephritis, which is an inflammation of the glomerulus, a functional unit of the kidney formed by a tangle of capillaries, where blood is filtered and urine is formed.

With regard to the care of patients with chronic kidney disease, who are already on dialysis and contracted the new coronavirus, the nephrologist explains that they must follow the protocol established by the Brazilian Society of Nephrology (SBN). “SBN was very punctual and effective right at the beginning of the pandemic. Hospitals and clinics are separating patients with Covid-19 in specific settings for dialysis. It is interesting because, in these places, for years we have already had the isolation of patients who contracted hepatitis B, in a sector called the ‘yellow room’ ”, he says, stressing that, even infected with the new coronavirus, the patient with chronic kidney disease there is no need to suspend treatment, since hemodialysis is what keeps patients with quality of life.

Bed treatment – According to Luiz Guilherme Almeida, patients with acute kidney injury – suspected or tested positive for the new coronavirus – as soon as they enter one of the HM beds, they are evaluated by the hospital’s nephrology team, which is responsible for evaluation of the need or not of hemodialysis. “Often, thanks to the expertise of the nephrologist who evaluates the patient, it is possible to prevent the acute injury from progressing to terminal stages, requiring dialysis. Therefore, it is important for the assisting physician, as soon as he identifies any signs of acute injury, he talks to the nephrologist, so that he can help filter the prescription itself, take nephrotoxic drugs and evaluate the hydration or hyperhydration of the patients. , factors that can damage the kidneys. Much of this acute kidney damage evolves without the need for dialysis. In the case of patients who need dialysis, they are transferred from the semi-intensive unit to the ICU, where our hemodialysis points are located, dedicated to those patients with acute conditions ”, he says.

After hospital discharge – Luiz Guilherme Almeida says that, after discharge from the patient with chronic kidney disease, the nephrologist prepares a detailed report on the treatment the patient received during the days he was hospitalized. “They are returned to their original clinics to continue the treatment. The report issued by the HM doctor facilitates the nephrology team at the dialysis clinic to maintain or adjust the treatment. Patients with acute kidney injury, who had the need for dialysis and who did not revert, are also referred to the dialysis clinics of our reference. However, a lot from the point of view of chronic treatment will be the responsibility of the nephrology team that will treat you. Patients who were discharged from the hospital and did not need dialysis, they also need follow-up with the nephrologist. The treatment can be carried out in an office, not necessarily in a dialysis clinic ”, explains Luiz Guilherme de Almeida.

The view of infectious diseases – According to infectious diseases and medical manager of the HM, Sarah Dominique Dellabianca, acute kidney damage damages the immune system, as it unstable the body as a whole. In the professional’s observation, kidney paralysis is something very feared in intensive care and, from the point of view of infectious diseases, it impacts on a higher mortality for any infection that the patient may develop. “In addition to Covid-19, the patient with acute kidney injury is subject to contracting a hospital infection associated with the catheter and mechanical ventilation. The clinical management of this patient is much more intensive and strict. As the kidneys are not working properly, the patient’s urine is therefore not at an adequate level. Therefore, substances harmful to the body are overloaded in the blood, damaging other tissues and organs, which can cause bleeding. If the patient develops uremia, which is the accumulation of urea, he may have bleeding in the intestinal tract, which favors the translocation of bacteria in his body ”, he stresses.


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