Early Predictive Factors of Acute Kidney Injury in Severely Burned Patients
Published Date: September 20, 2017
Early Predictive Factors of Acute Kidney Injury in Severely Burned Patients
Hamza D. Sama 1*, Tchetike PF1,2, Egbohou P1, Amouzou KS3, Moghazy A4, Kabore F5, Zoumenou E6, Tomta K1, Hemou PF7, and Chobli M6
1Service of Anesthesia Resuscitation, CHU Sylvanus Olympio, Lomé, Togo
2Service of the Great Burns, Hôpital Saint Louis, Paris, France
3Department of Plastic Surgery and Burns, CHU Sylvanus Olympio, Lomé, Togo
4Department of Plastic Surgery and Burns, Ismailia, Egypt
5Service of Anesthesia Resuscitation, CHU Blaise Compaoré, Ouagadougou, Burkina Faso
6University Hospital of Emergency, SPAR CNHU Cotonou, Bénin
7University Hospital Kara, Togo
*Corresponding author: Hamza D. Sama, Department of Anesthesia, Resuscitation and Critical Care Medicine, Sylvanus Olympio University Teaching Hospital, Lomé, Togo, E-mail: email@example.com.
Citation: Sama HD, Tchetike PF, Egbohou P, Amouzou KS, Moghazy A, et al. (2017) Early Predictive Factors of Acute Kidney Injury in Severely Burned Patients. J Eme Med Int Care 3(3): 122
Objective: To determine the early predictive factors of acute kidney injury in severe burned patients under mechanical ventilation.
Patients and Method: We conducted a three-year retrospective study analysis of severely burned patients hospitalized at the burn treatment center in Saint Louis Hospital in Paris from 1st January 2012 to 1st January 2015. The KDIGO 2012 classification of the acute renal failure was used. Patients aged over 18-year-old, admitted to the ICU fulfilling the criteria of tracheal intubation and under mechanical ventilation were included in this study.
Results: Over our study period from 1st January 2012 to 1st January 2015, 89 patients were included with a prevalence of acute renal failure at 37% using the KDIGO classification. Taking into account the use of extra-renal purification, the initial severity of the burn (p < 0.001), day zero of hospital admission creatinine (p < 0.001) and inhalation of smoke (p = 0.017) seems to predict the occurrence with the introduction of extra-renal purification in severe burns. Study of the initial severity of the burn and the occurrence of acute renal failure gives a p value of 0.09.
Conclusion: No early predictive factor of acute renal failure in severe burn was found in our study.
Keywords: Early predictive factors; Severe burns; Acute renal failure
Acute Kidney Injury (AKI) is a clinical and biological syndrome defined as a rapid decline in renal filtration function. AKI is one of the most frequent diseases in intensive care units reported in as 35% to 65% ICU patients . AKI is a risk factor for 45% to 55% mortality and major morbidity [2,3] with level of serum creatinine as low as 26.2 μmol/l . Definition of AKI has evolved along the past years [3,4]. In 2012 KDIGO (Kidney Disease Improving Global Outcome) experts had harmonized definitions of AKI . Therefore, definition of AKI became: rise of plasma creatinine over 26.5 μmol/l within 48 hours or rise of plasma creatinine over 1.5 times the last known value or what is supposed to be the value within the seven previous days, or oliguria of 0.5 ml/kg/h or lower within at least six hours. Severely burned patients are population at high risk of AKI due to a prolonged and increased inflammatory process.
Few studies using RIFLE score  reported a prevalence of 24–53.3% and a mortality rate range 25% and 57% [7–9]. Only few studies have been conducted about early predictive factors of AKI among severely burned population.
The purpose of this study was to determine early risk factors of AKI using the KDIGO 2012 score.
This was a retrospective study based on the analysis of medical charts of burn patients who were treated with mechanical ventilation in the Burn care center of Saint Louis (Paris, France). The duration of study was three years from 1st January 2012 to 1st January 2015. Care protocol was standardized in the study period for fluid resuscitation, surgical management and extra-renal purification. In case of kidney failure based on serum creatinine, extra-renal purification was indicated for oligouria, anuria not responding to volume expansion, non-controllable metabolic acidosis, threatening hyperkalemia, and pulmonary edema not controllable by diuretics treatment.
Patients aged over 18-year-old, admitted to the Saint Louis burn ICU fulfilling the criteria of tracheal intubation and under mechanical ventilation were included in this study. Patients that had preexisting kidney injury and those for whom care limitation was indicated within the first 48 hours was excluded in this study.
Following parameters have been documented: age, gender, times of burn injury and admission, eventual administration of Cyanokit in pre-hospital setting, the total burn surface area (TBSA), Simplified Severity Index (SSI) II at admission time; highest serum creatinine of the first seven days, use or extra-renal purification (type and modality), usage of nephrotoxic medication, urea and serum creatinine at discharge from ICU, and mortality rate. Patients have been divided in to three groups for the early predictive factors for kidney failure: G1, general population (all patients aged over 18-yrear-old), G2 (patients having extra renal purification), G3 (patient not having extra renal purification).
Data were collected and analyzed using SPSS 2015-IBM. Quantifiable variables were expressed by mean and standard deviation, and unquantifiable variables were expressed by number and percentage. Student t-test and Chi-Square tests were used to compare continuous and discontinuous variables. Tests were considered significant for a p value inferior to 0.05.
In the three years period, 92 patients were eligible for the study. Among them, three were not included because they were admitted 48 hours after the burn injury, thus 89 patients were included in the study. Characteristics of the global population at admission time are reported in the table 1.
Table 1 : Characteristics of the population.
Early AKI was diagnosed in 32 patients (37%) during the early seven days of care. Among them, 19 had dialysis thus representing 31.3% of AKI group and 11.3% of global population. In the study period 18 (20.2%) patients died.
With regard to groups, 89 patients belong to G1 (global population), 11 patients G2 (patients that have extra-renal purification), and 78 patients G3 (patients that have no extra-renal purification). In comparison, patients with AKI were older, had greater TBSA, higher SSI-II, and serum creatinine at day zero of hospital admission. SSI- II had tendency to predict early AKI among burned patients under mechanical ventilation (Table 2).
Table 2: Comparison of patients with AKI and without AKI.
For the purpose to compare patients with early AKI having purification three groups have been defined as depicted in table 3. Comparative observation of the three different groups showed that patient having purification were older, with more extended TBSA, statistically significant for SSI-II (p < 0.001) and serum creatinine at day zero of hospital admission (p < 0.001). TBSA tended to predict extra renal purification in burns under mechanical ventilation (p = 0.073).
Table 3: Comparison of extra renal purification and non extra renal purification patients.
When comparing risk factors that predict extra renal purification in burned patients, we studied: comorbidities (HTN, diabetes), inhalation injuries. There was no significant difference among patients under dialysis with or without HTN, diabetes, use of angiotensin converting enzyme (ACE) inhibitor, diuretics and pre-hospital Cyanokit use. Statistically significant difference was found among patients with inhalation injury and those with no inhalation injury (p = 0.017). About patients with proven smoke inhalation, those without extra renal depuration have a high rate 25 (78,8%).
Our retrospective study found that prevalence of AKI was 37% according to KDIGO 2012. Dialysis was performed for 11.3% of the global population. Mortality in our population was 20%. TBSA tended to predict extra renal purification as well but with no statistically significant value. When considering factors associate to the burn, only inhalation injury was predictive for extra renal purification. These results are on line with what is generally found in the literature [7–11]. In a study conducted using RIFLE as diagnostic method, prevalence of AKI ranged between 24% and 53%, while a study using extra renal purification showed a prevalence ranging between 4.8% and 14.6% as depicted in table 4. Prevalence in our study seemed to among the highest of all reported. This can be explained by the severity of burns in the patients of our study, the role of mechanical ventilation on renal perfusion, sensibility and specificity of KDIGO 2012 score for AKI.
Table 4: Comparaison of AKI prevalence on severe burn patient.
The mortality in our study was 20.2%, low when compared with others datas that reached 80% in a study . Generally, mortality rate tended to lower along the time. This could be attributed to more insight in pathophysiology of burns and optimization of surgical and resuscitation care. Thus, early surgery in burns that comprises escharotomy, multiple step surgery on limited surfaces, contributes to reduce incidence of subsequent rhabdomyolysis and AKI due to hypovolemia by massive blood loss. Precise evaluation of TBSA by a certified plastic surgery board, volemia monitoring with PICCO catheter as well as urine output monitoring allow to avoid insufficient resuscitation that cause of AKI by ischemia, or fluid overload that cause AKI by congestion.
In spite of the severity of burns, TBSA did not appear as a predictive factor in our study but tended to predict extra-renal purification. Nevertheless, Sabry et al.  found TBSA was predictive for AKI in a study of 40 patients presenting with mild to severe burn injuries. Moreover, Schneider et al.  in a study of 220 severely burned patients reported that TBSA was a predictive factor for AKI past the 48 hours of care.
Mean age in our patients was 49.7-year-old. In a study related to markers of AKI in thermal burned patients, Sabry et al.  did not found age to be a predictive factor for AKI. Mean age of patients in this study was 39.7-year-old. In addition, Schneider et al.  reported that age only predicted AKI with no discrimination even though their study population was important. In our study, absence of age as predictive factor may be the fruit of optimal care of burns nowadays, sensibility and specificity of KGIDO score, young age of patients, and the low population number. Comorbidities as diabetes and HTN, and ongoing medications as ACE inhibitors and diuretics were not positive predictive factors. Other factors as organ failure, under or over fluid resuscitation, as well as inhalation injury had a non-negligible role. Even though septic episodes are generally seen far in the care of severely burned patients, in our center, from the 7th day, care of severe septic shock in patients with AKI [15,16] may contribute to considerably decline in mortality and morbidity.
Prevalence of early AKI in our study was 37% when using KDIGO classification. Only initial severity of the burn injury tends to predict an AKI. This negative result could be the fact of small study population, and optimization of burn care nowadays. When using AKI as need for extra renal purification, initial severity of burns, inhalation injury, serum creatinine at day zero of hospital admission appear to be predictive factors for extra-renal purification. The total burn surface area tends to predict extra-renal purification as well, but with no discrimination. AKI remains frequent and seen in severe burned patients. Nevertheless, no universally accepted recommendation about prevention as well as care of this complication exists at date. Further multicenter retrospective studies could help to fill this gap.
Conflict of Interest
Authors declared that they have no conflict of interest.
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Copyright: © 2017 Sama HD, et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.