Over the last decade, the number of liver transplantation surgeries conducted has increased vastly [1]. With this increase, postoperative rates of survival are improving as well [1]. However, the likelihood of patients experiencing postoperative complications has also risen [1]. Acute kidney injury (AKI) is one of the most pressing complications for physicians to consider, given its frequency and deadliness following liver transplant surgery [2]. To combat AKI, medical practitioners need to understand its causes and comorbidities.
Among the risk factors for AKI, most are preoperative [2]. A 5-year retrospective study of 424 patients found that female sex, a weight greater than 100 kg, pre-existing diabetes mellitus, and severity of liver disease (indicated by a high Child-Pugh score) dramatically increase a patient’s risk of developing AKI [3]. Genetic factors may also play a role. One study found that patients who had the IL4-33 T/T genotype were more likely to develop AKI than those with alternate genotypes [2]. The researchers believe this association could emerge from the gene’s effect on inflammatory and anti-inflammatory cytokines, which impact the development of AKI [2]. Another preoperative predictor of AKI may be a higher body mass index (BMI) [4]. However, researchers offer this conclusion with a caveat, given how end-stage liver disease can render BMI an inaccurate measure of body composition [4].
Intraoperative risk factors are also important to note. One significant risk factor is the loss of blood during surgery, accompanied by transfusion of either red blood cells or plasma, which are associated with AKI [2, 3, 4]. Some studies have suggested that blood loss and transfusion significantly increase the risk of AKI when occurring in large quantities and when the blood that patients receive has been stored for a long time [2]. Hypotension is also a risk factor, with AKI incidence increasing the longer a patient’s mean arterial pressure (MAP) is less than 65 mmHg [5]. Other cardiac risks include elevated baseline right ventricular end-diastolic volume and baseline central venous pressure following the administration of anesthesia [2]. Additionally, longer surgeries (>480 minutes) are associated with a higher risk of developing AKI [2].
Certain factors related to the donor liver also increase the risk of AKI in certain liver transplant recipients. One study followed 88 liver transplant recipients whose liver donations came from victims of cardiac death [6]. The researchers found that these patients experienced a greater incidence of AKI following surgery, compared to patients who had received donation after brain death [6]. Scientists also noted how hepatic ischemic reperfusion injury consistently predicted postoperative renal dysfunction [6]. Other experiments have corroborated these findings by demonstrating how warm and cold donor liver ischemia time is strongly associated with AKI [2].
Unfortunately, AKI is a condition for which no effective treatment has yet been developed [2]. Therefore, it is integral that physicians take these risk factors into account to mitigate the likelihood of this condition.
References
[1] F. M. Carrier et al., “Effects of intraoperative hemodynamic management on postoperative acute kidney injury in liver transplantation: An observational cohort study,” PLoS One, vol. 14, no. 8, p. 1-14, August 2020. [Online]. Available: https://doi.org/10.1186/s12871-020-01228-y.
[2] I. M. Iljinsky and O. M. Tsirulnikova, “New trends in the study of post-transplant acute kidney injury after liver transplantation,” Vestnik Transplantologii I Iskusstvennyh Organov, vol. 21, no. 4, p. 108-120, February 2020. [Online]. Available: https://doi.org/10.15825/1995-1191-2019-4-108-120.
[3] I. A. Hilmi et al, “Acute kidney injury following orthotopic liver transplantation: incidence, risk factors, and effects on patient and graft outcomes,” British Journal of Anaesthesia, vol. 114, no. 6, p. 919-926, June 2015. [Online]. Available: https://doi.org/10.1093/bja/aeu556.
[4] A. Mrzljak et al, “Pre- and intraoperative predictors of acute kidney injury after liver transplantation,” World Journal of Clinical Cases, vol. 8, no. 18, p. 4034-4042, September 2020. [Online]. Available: https://doi.org/10.1093/bja/aeu556.
[5] A. Joosten et al., “Intraoperative hypotension during liver transplant surgery is associated with postoperative acute kidney injury: a historical cohort study,” BMC Anesthesiology, vol. 21, no. 1, p. 1-10, January 2021. [Online]. Available: https://doi.org/10.1186/s12871-020-01228-y.
[6] J. A. Leithead et al, “Donation After Cardiac Death Liver Transplant Recipients Have an Increased Frequency of Acute Kidney Injury,” American Journal of Transplantation, vol. 12, no. 4, p. 965-975, January 2012. [Online]. Available: https://doi.org/10.1111/j.1600-6143.2011.03894.x.