Clinical characteristics and risk factors for severe burns complicated by early acute kidney injury

Abstract

Background: Early acute kidney injury (AKI) is a frequent fatal complication of severely burned patients. Although significant progress has been made in fluid resuscitation, intensive care, and renal replacement therapy (RRT) technology in recent years, the incidence and mortality rate in severely burned patients with AKI remains considerable. This study aims to provide theoretical evidence for prevention and treatment by investigating the clinical characteristics and risk factors influencing the incidence and severity of early AKI in severely burned patients.

Methods: This 3-year retrospective, single-center study was conducted in critically ill burned patients admitted to the Burn ICU at Guangzhou Red Cross Hospital of Jinan University. Patients whose age is older than 18 years with ≥30% burned total body surface area (TBSA) were enrolled in this study. Those patients who arrived at our burn ICU>72h after injury or died within 48h from arrival were excluded. Data of 128 patients were studied in the final. Demographic and injury details were recorded. KDIGO criteria were used to assess the incidence and severity of early AKI. Factors influencing early AKI were determined using univariate and multiple logistic regression analysis.

Results: Between January 2016 and December 2018, Data from 128 critically ill burned patients were available for analysis. The median age was 44.9±16.8 years; 68.8% of the patients were male. The median TBSA% was 60 (IQR, 41.3-80%). According to the KDIGO criteria, 36 patients (28.3%) developed early AKI, as follows: stage 1 AKI, 69.4% (25/36); stage 2 AKI, 13.9% (5/36); and stage 3 AKI, 16.7% (6/36). The incidence of early AKI was associated with TBSA%, full-thickness TBSA%, abbreviated burn severity index on admission (ABSI), inhalation injury, mechanical ventilation, cardiovascular complications, and rhabdomyolysis. Multiple logistic regression analysis indicate that TBSA% (OR=0.224, p=0.007), full-thickness TBSA% (OR=0.254, p=0.014), ABSI (OR=18.326, p=0.009), and rhabdomyolysis (OR=24.036, p=0.000) were independent risk factors for the occurrence of early AKI. Significant factors influencing the severity of early AKI included full-thickness body surface area burns, electrical burns, and rhabdomyolysis. Full-thickness TBSA% (OR=1.437, p=0.041) and rhabdomyolysis (OR=5.401, p=0.035) are associated with mortality. The risk of death due to the occurrence of AKI was 5.407 in the Cox model adjusted for TBSA%, full-thickness body surface area burns, ABSI and rhabdomyolysis. Three patients died, all of whom had stage 3 AKI, accounting for 8.3% (3/36) of AKI patients. The death rate of stage 3 AKI who did and did not receive early RRT was 33.3% and 66.7%, respectively.

Conclusion: Rhabdomyolysis is an independent risk factor for early AKI and closely related to the severity of early AKI in critically ill burned patients. Although with a high incidence of early AKI in severely burned patients, most of them are mild. Early adequate fluid resuscitation, timely and effective escharotomy, reducing the incidence and severity of rhabdomyolysis, most of them can achieve a relatively good prognosis.

Keywords: Acute kidney injury (AKI); Burns; CRRT; Fluid resuscitation; Rhabdomyolysis.