Incidence of Post-laparotomy Acute Kidney Injury Among Abdominal Trauma Patients and Its Associated Risk Factors at King Abdulaziz Medical City, Riyadh

Background This research study investigates the prevalence of acute kidney injury (AKI) in trauma patients undergoing emergency laparotomies. AKI is a common complication in major surgeries and is associated with various adverse effects. The study aims to explore the relationship between AKI and other comorbidities in this specific context. Methodology This is a retrospective cohort study. All patients who had laparotomy after abdominal trauma at King Abdulaziz Medical City (KAMC) and met the inclusion criteria were included in the study. Nonprobability consecutive sampling was used. Data were collected by chart review using the Best-Care system at KAMC. Descriptive statistics were used to summarize and describe the characteristics of the study participants. Frequencies and percentages were calculated for categorical variables, such as comorbidities. For continuous variables, mean and standard deviations were calculated and tabulated. All statistical calculations were performed using IBM SPSS Statistics for Windows, Version 27.0 (IBM Corp., Armonk, NY, USA). Results This research study included 152 patients who underwent laparotomy, and the majority of patients (146, 96%) did not experience AKI. Several comorbidities were observed, with hypertension and diabetes being the most prevalent at 37 (24.3%) and 35 (23%), respectively. Intraoperative hypotension was experienced by 23 (15.1%) patients, while 129 (84.9%) did not have this issue. Norepinephrine was the most common vasopressor used (25.7%), followed by ephedrine and a combination of norepinephrine and epinephrine. Gender and age groups did not show significant associations with AKI, comorbidities like diabetes, heart failure, and chronic kidney disease (CKD) demonstrated significant relationships with AKI. There was no significant difference in eGFR and serum creatinine baseline levels between patients meeting AKI criteria and those who did not. Conclusions The low overall incidence of AKI in this patient population is encouraging. However, healthcare professionals must be aware of the significant impact of comorbidities such as diabetes, heart failure, and CKD on AKI development. Vigilant monitoring of postoperative kidney function, particularly serum creatinine levels within the first 48 hours, is essential for early detection and timely intervention. By understanding and addressing these risk factors, healthcare providers can take proactive steps to prevent and manage AKI in patients undergoing laparotomy, ultimately leading to improved patient outcomes and reduced healthcare costs.


Introduction
Emergency laparotomies is an umbrella term that encompasses many emergent surgical procedures, whether it is trauma-or non-trauma-related. Although emergent laparotomies are lifesaving procedures, they are associated with a higher risk of mortality and morbidity compared to elective surgeries [1,2]. The preoperative, intraoperative, and postoperative statuses hold significant predictive value for the prognosis. In a study of postoperative complications following emergency laparotomy, it was found that age is one of the major risk factors affecting mortality. Specifically, 30% of patients aged 80 or older died within 28 postoperative days [3]. Additionally, the presence of other comorbidities such as hypertension, diabetes, coronary artery disease (CAD), and complications that occur during the surgery such as intraoperative hypotension and postoperative complications, including hemodynamic instability and nosocomial infections, greatly negatively influence the prognosis [4].
AKI is a clinical syndrome characterized by a precipitous decline in the function of the kidney and can affect its structure. It encompasses various etiologies, including kidney-specific diseases (e.g., acute interstitial nephritis, acute glomerular, and vasculitic renal diseases), nonspecific conditions (e.g., ischemia and toxic injury), and extrarenal pathology (e.g., acute postrenal obstructive nephropathy) [5]. According to the definition provided by Kidney Disease: Improving Global Outcomes (KDIGO), AKI is confirmed by any of the following: increase in serum creatinine (SCr) by 0.3 mg/dL (26.5 μmol/L) or more within 48 hours; increase in SCr to 1.5 times or more of the baseline, which is known or presumed to have occurred within the prior seven days; or urine volume less than 0.5 mL/kg per hour for six hours or more [5]. AKI is a common complication of patients undergoing major surgery and is associated with both short-and long-term complications and adverse effects such as ICU admission, longer hospital stay length, and chronic kidney disease (CKD) [3]. A study conducted in Portugal for noncardiac surgical patients (231 emergency surgery) showed that AKI accounts for 33% of postoperative intensive care unit (ITU) admissions [6]. Moreover, a UK cohort study done on 144 patients who underwent emergency laparotomy demonstrated that the incidence of renal complications was reported in 11.8% of the cases.
This study aims to identify the prevalence of acute kidney injury (AKI) in trauma patients undergoing laparotomy and the association between AKI in trauma-related emergency laparotomy and other comorbidities.

Materials And Methods
This study was conducted at King Abdulaziz Medical City (KAMC), a tertiary National Guard Hospital in Riyadh, Saudi Arabia. The hospital was instituted in May 1983, with a capacity of 3,133 beds approximately. It has a level I trauma center and serves as the trauma center in the region. The study is a retrospective cohort study that aims to investigate the Incidence of post-laparotomy AKI among abdominal trauma patients and associated risk factors at KAMC, Riyadh. It included all patients who had laparotomy after abdominal trauma. The sampling technique utilized for the study was nonprobability consecutive sampling, including all patients who met the inclusion/exclusion criteria. Data were collected by chart review using the Best-Care system at KAMC, and only the research team members collected the data. The collected data included patient demographics, comorbidities, quantitative factors such as estimated glomerular filtration rate (eGFR), serum creatinine baseline and after 48 hours from surgery, and surgery-related and aftersurgery data such as the need for renal replacement therapy (RRT) and mortality.
The statistical analysis was conducted to examine the relationships and differences between variables in the study, as well as to determine the significance of the findings. The analysis involved both descriptive and inferential statistical tests.
Descriptive statistics were used to summarize and describe the characteristics of the study participants. Frequencies and percentages were calculated for categorical variables, such as comorbidities. For continuous variables, mean and standard deviations (SDs) were calculated and tabulated.
Additionally, the Fisher's Exact Test and Mann-Whitney U test were conducted to find the association of different variables with AKI. The nonparametric Mann-Whitney U test was chosen owing to the nonnormal distribution assessed by the application of the Kolmogorov-Smirnov test (P < 0.05). The significance level for all statistical tests was set at P < 0.05, indicating a 95% confidence interval. All statistical calculations were performed using IBM SPSS Statistics for Windows, Version 27.0 (IBM Corp., Armonk, NY, USA).

Results
A total of 152 patients were included in the analysis and evaluated for AKI. The majority of patients (146, 96%) did not meet the KDIGO criteria for AKI. On the other hand, a smaller proportion of patients, specifically 6 (4 %) individuals, met the criteria for AKI ( Figure 1).

FIGURE 1: Patients meeting the KDIGO criteria of AKI.
AKI, acute kidney injury; KDIGO, Kidney Disease: Improving Global Outcomes Table 1 provides descriptive statistics on the demographic data and comorbidities related to AKI postlaparotomy. The study included a total of 152 patients. Among them, 56 (36.8%) individuals were female, while 96 (63.2%) individuals were male. Regarding age distribution, the majority of patients 79 (52%) were aged between 19 and 50 years, followed by 33 (21.7%) who were aged between 51 and 70 years, and the rest were aged between 0 and 18 and >70 years. Regarding body mass index (BMI) categories, the overweight and normal categories encompassed the majority of patients, accounting for 50 (32.9%) and 45 (29.6%), respectively. The comorbidities observed in the patients were hypertension in 37 (24.3%) individuals, diabetes in 35 (23%) individuals, and other comorbidities in a few patients.      Table 3 provides information on qualitative factors associated with AKI post-laparotomy. The table presents the count and percentage of patients meeting or not meeting the KDIGO criteria for AKI based on various factors, along with the associated P-values. The analysis of gender showed that 2 (3.6%) females and 4 (4.2%) males met the KDIGO criteria for AKI, while the majority did not. The P-value (1.000) suggests no significant association of gender with AKI. Across different age groups, higher proportions of AKI were observed in the 51-70 years group (3, 9.1%) and the group aged more than 70 years (2, 10%), in comparison to the other age groups. However, the overall P-value (0.061) indicates a lack of statistical significance. Regarding comorbidities, diabetes, and heart failure showed a significant association with AKI (P < 0.05). For diabetes, 4 (11.4%) patients met the criteria, while 31 (88.6%) did not (P = 0.025). For heart failure, 2 (22.2%) patients met the criteria, while 7 (77.8%) did not (P = 0.041). CKD also showed a significant association with AKI. Two (50%) patients met the criteria, while 2 (50%) did not (P = 0.008). The rest of the comorbidities did not show any significant association. The remaining factors, including duration of surgery, intraoperative hypotension, vasopressor use, blood loss, post-laparotomy renal replacement therapy, and patient mortality, did not demonstrate significant associations with AKI.

Qualitative factors
Meeting the KDIGO criteria of AKI?

Discussion
In this study, we investigated the incidence of AKI following laparotomy, exploring various demographic, comorbidity, surgical, and qualitative factors that may influence AKI development.
Our study examined 152 patients who underwent laparotomy, with 6 (4%) patients meeting the KDIGO criteria for AKI after laparotomy. This indicates a relatively low incidence of AKI in the immediate postoperative period in this particular patient population. The majority of patients (146, 96%) did not develop AKI following the surgical procedure.
Regarding the demographic data, we observed a higher proportion of males 96 (63.2%) compared to females 56 (36.8%) in the study cohort. Age distribution showed a significant number of patients 79 (52%) falling into the group of 19-50 years, and the most commonly encountered comorbidities were hypertension 37 (24.3%) and diabetes 35 (23%). The associations between gender and age groups with AKI did not reach statistical significance, suggesting that AKI development was not influenced significantly by these demographic factors.
However, comorbidities such as diabetes, heart failure, and CKD were found to be significantly associated with AKI. Patients with diabetes exhibited an 11.4% incidence of AKI, while those without diabetes had a much lower rate (P = 0.025). Similarly, heart failure showed a 22.2% incidence of AKI compared to 7.8% in patients without heart failure (P = 0.041). CKD also demonstrated a strong association with AKI (P = 0.008). These findings emphasize the importance of recognizing preexisting comorbidities, as they can play a critical role in the development of AKI following laparotomy [7].
Regarding the descriptive statistics on surgical factors, the duration of surgery was found to be statistically nonsignificant, with the majority of patients falling into Class 1 68 (44.7%) and Class 2 65 (42.8%). However, this finding is not consistent with previous studies that reported a positive correlation between prolonged surgery duration and AKI incidence. These studies showed that longer surgical durations might increase the risk of AKI due to prolonged exposure to anesthesia and potential hypoperfusion of the kidneys [8,9].
Intraoperative hypotension is another critical factor that may contribute to the development of AKI. In this study, 23 (15.1%) of patients experienced intraoperative hypotension, while the majority did not. Hypotension can lead to reduced renal blood flow, resulting in renal ischemia and subsequent injury [10]. The incidence of AKI in patients who experienced intraoperative hypotension should be compared to those who did not to determine if there is a significant association between AKI and intraoperative hypotension.
Vasopressor use, particularly norepinephrine, was administered to a significant proportion of patients 39 (25.7%). Previous studies have suggested that vasopressor use during surgery can affect renal perfusion and function, potentially contributing to AKI [11,12]. The impact of different vasopressors on AKI incidence should be explored further in future studies.
Blood loss during surgery is another factor that may influence the development of AKI. In this study, the majority of patients (80.3%) were categorized as Class 1 for blood loss. Significant blood loss can lead to hypotension and decreased renal perfusion, contributing to AKI development [13]. Comparing AKI incidence among patients with varying levels of blood loss may help confirm this association.
In this study, post-laparotomy RRT was required in 9 (5.9%) of the patients. The need for RRT indicates severe AKI and a higher risk of adverse outcomes [14]. Identifying factors associated with RRT requirements can help in risk stratification and timely intervention.
Regarding the qualitative factors associated with AKI post-laparotomy. Gender did not show a significant association with AKI, but contradicting other studies showed a significant association in both males and females depending on age groups as per this reference study [15]. The role of gender in AKI development remains controversial and warrants further investigation.
In terms of age, both the 51-70 years group and the more than 70 years group exhibited higher proportions of AKI. However, the overall P-value did not achieve statistical significance. Advanced age has been recognized as a risk factor for AKI in various studies [16,17], and a larger sample size might reveal significant associations in this study.
Comorbidities such as diabetes, heart failure, and CKD showed significant associations with AKI. Diabetic patients had a higher AKI incidence (11.4%), consistent with previous research that reviewed a casematched retrospective study that showed the incidence of postoperative AKI in diabetes mellitus (DM) was 30.7%. Additionally, another study reviewed in the same research showed high DM prevalence in AKI with 19.6% [18]. Heart failure and CKD were also significantly associated with AKI, indicating the importance of recognizing these conditions as risk factors during preoperative evaluation [19].
Regarding the quantitative factors associated with AKI. There was no significant difference in eGFR between patients meeting AKI criteria and those who did not. This suggests that the baseline kidney function alone may not be sufficient to predict AKI occurrence, and other factors may be more influential [20].
However, the mean serum creatinine level after 48 hours from surgery was significantly higher in patients meeting the AKI criteria compared to those who did not. This indicates that the postoperative serum creatinine level can be a valuable indicator of AKI development and supports the findings of previous studies [21].
It is essential to acknowledge some limitations of our study. First, the relatively small sample size may have affected the statistical power to detect certain associations, particularly when examining rare events like AKI. Expanding the sample size in future studies could strengthen the analysis. Additionally, there might be some missing quantitative data that could influence the assessment of AKI occurrences. By placing more emphasis on gathering quantitative data in the future, we can potentially achieve a more accurate evaluation of AKI. Additionally, this study's single-center design might limit the generalizability of the findings to other populations and healthcare settings.

Conclusions
The low overall incidence of AKI in this patient population is encouraging. However, healthcare professionals must be aware of the significant impact of comorbidities such as diabetes, heart failure, and CKD on AKI development. Vigilant monitoring of postoperative kidney function, particularly serum creatinine levels within the first 48 hours, is essential for early detection and timely intervention. By understanding and addressing these risk factors, healthcare providers can take proactive steps to prevent and manage AKI in patients undergoing laparotomy, ultimately leading to improved patient outcomes and reduced healthcare costs.

Additional Information
Disclosures