Key Points Of Early Diagnosis And Graded Treatment Of AKI

Due to infection, trauma, shock, and other factors, severe patients are more likely to develop new acute kidney injury (AKI) or aggravate the original chronic renal insufficiency, which in turn aggravates the patient's condition and affects the prognosis. Therefore, severe patients should avoid the occurrence of AKI as much as possible, and once AKI occurs, early diagnosis and early treatment should be done as much as possible.

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Epidemiology of AKI

In patients with AKI, fluid overload, severe electrolyte disturbance, acid-base imbalance, and azotemia often lead to systemic multi-system dysfunction, which is one of the important causes of multiple organ dysfunction syndromes (MODS) and is also One of the most important factors leading to the death of critically ill patients.

The incidence of acute renal failure (ARF) in severe patients ranges from 5% to 20%, patients with severe infection and ARF account for 11% to 64%, and the mortality rate ranges from 10% to 50%, and the mortality rate increases with the severity of ARF level increases. However, whether AKI directly leads to the final death of patients is still controversial, and different scholars have different understandings.

Causes of AKI

There are many risk factors leading to the occurrence of AKI, common risk factors include infection, shock, trauma, and so on. According to the KDIGO guidelines, the causes of AKI include exposure factors and patient susceptibility factors, among which exposure factors include systemic infection, severe illness, shock, burns, trauma, cardiac surgery (especially cardiopulmonary bypass surgery), major non-cardiac surgery, renal Toxic drugs, contrast media, and consumption of poisonous plants or animals; susceptibility factors include dehydration or volume depletion, advanced age, female, black race, chronic kidney disease, chronic diseases (heart, lung, liver, etc.), diabetes, tumors, and anemia. In preventing AKI, the relevant risk factors should be highly valued and dealt with.

Prevention of AKI

AKI is one of the most common complications of major cardiac surgery, burns, severe infection, and shock, so we should be alert to the occurrence of AKI. Avoid the use of nephrotoxic drugs, such as aminoglycoside antibiotics, amphotericin, etc., especially in patients with AKI risk factors or existing AKI; prevent contrast agent-related AKI (CI-AKI), and use iodine contrast agent intravenously or orally Before assessing the risk of CI-AKI in patients, if there is a high risk, choose other alternative examination methods as much as possible, use as low a dose of contrast agent as possible, and try to use isotonic or low-osmotic iodine contrast agent to reduce kidney damage. When contrast agents must be used, appropriate hydration therapy and furosemide diuresis can help reduce the incidence of AKI after angiography, especially in emergency surgery.

Early diagnosis of AKI

1 AKI grading diagnostic criteria

The definition of ARF is not conducive to the early diagnosis of AKI, cannot reflect the severity of the disease, and cannot be used for graded diagnosis and treatment. KDIGO criteria (AKI stage 1, 2, 3), see the table below. The mortality rate of AKI patients is positively correlated with the severity of AKI and the number of other organ failures after AKI. Therefore, early diagnosis and early treatment of AKI should be emphasized to minimize its adverse effects on patients.

2 Biomarkers

Biomarkers are effective indicators for the early diagnosis of AKI, and the value of combined diagnosis is higher. The study found that tissue inhibitors of metalloproteinase (TIMP)-2 and insulin-like growth factor-binding protein (IGFBP)-7 were early indicators for predicting AKI, and AKI could be predicted 4 hours after surgery. Biomarkers can not only be used as early diagnostic indicators of AKI, but also may identify the etiology of renal injury (such as ischemia and hypoxia, drug toxicity, systemic infection, or the coexistence of multiple causes), the site of injury (such as glomeruli, renal tubules) and the degree of progression of the disease, and make early risk stratification and prognosis assessment for AKI.

AKI treatment

1 Hierarchical treatment of AKI

The KDIGO guidelines recommend that patients should be graded according to different stages of AKI: for those with high-risk factors, nephrotoxic drugs should be stopped, volume status and renal perfusion pressure should be evaluated, hemodynamic monitoring should be considered, and serum creatinine and urine should be monitored. Control blood sugar and avoid using contrast medium as much as possible.

For patients with stage 1 AKI, non-invasive methods should be used to confirm the diagnosis, and invasive diagnostic methods can also be considered; for patients with stage 2 AKI, it is necessary to verify whether the dose of all medications needs to be adjusted, and consider RRT and ICU admission; for patients with stage 3 AKI, The use of subclavian vein catheterization should be avoided as much as possible (it will easily lead to central vein stenosis and affect permanent catheterization).

The general treatment of AKI includes monitoring and stabilizing hemodynamics, appropriate fluid resuscitation, and ensuring renal blood perfusion; dealing with hyperkalemia, metabolic acidosis, etc.; while avoiding the use of nephrotoxic drugs, paying attention to adjusting the drugs excreted by the kidneys Dosage: Insulin is recommended to control the blood sugar of patients with severe AKI at 6.1-8.3 mmol/L, and 20-0 kcal/kg/d is recommended for AKI patients of all stages to provide adequate nutrition and avoid restricting protein intake due to delaying the start of RRT, the daily protein intake of non-high catabolic AKI patients is 0.8-1.0 g/kg/d, 1.0-1.5 g/kg/d for RRT patients, continuous renal replacement therapy (CRRT) or high catabolic 1.7 g/kg/d, AKI patients prefer to use enteral nutrition. Unless there is a state of fluid overload, diuretics are not recommended for the treatment of AKI; low-dose dopamine, fenoldopam, atrial natriuretic peptide, and recombinant human insulin-like growth factor are not recommended for the prevention and treatment of AKI.

2 Timing of RRT

When to start RRT in critically ill patients with AKI: life-threatening AKI-related complications occur, and cannot be quickly reversed by conventional treatment; h urine output ≤ 600 ml, progressive acidosis, pH value below 7.25, fluid accumulation more than 10% of body weight, progressive aggravation of pulmonary edema or deterioration of other non-renal organ functions.

3 Therapeutic dose of RRT

The therapeutic effect of RRT is mainly achieved through the regulation of solutes and solvents, so the therapeutic dose will have a direct impact on the therapeutic effect. Studies have shown that an RRT dose > 35 ml/kg/h has no significant effect on the prognosis of AKI patients.

Summarize

The incidence of AKI is high, and the severity affects the prognosis of patients; prevention of AKI is very important, and early AKI-graded diagnosis provides the basis for the graded treatment of AKI. RRT is an important means to treat AKI and prevent further deterioration of AKI. It is essential to grasp the timing of RRT initiation and formulate individualized treatment doses.

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