Anesthesia Considerations with Fatty Liver Disease
Fatty liver is described in the setting of non-alcoholic fatty liver disease (NAFLD) as well as alcoholic liver disease (ALD). While the pathogenesis of excess fat in the liver differs between the two conditions, both contribute heavily to the burden of liver disease worldwide. Indeed, non-alcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease worldwide. According to a recent systematic review and meta-analysis, the global prevalence of NAFLD increased from 25% in 1990-2006 to 38% in 2016-2019 1. Meanwhile, worldwide, ALD accounts for 4% of mortality and 5% of disability-adjusted life years, with Europe being the worst affected 2. Diminished liver function also affects an individual’s physical function as it relates to surgery and anesthesia. Given the global prevalence of fatty liver disease, it is critical to carefully address specific anesthesia considerations across clinical contexts.
The liver plays an important role in the metabolism and physiological homeostasis of the body 3. Given the unique structure and physiology of the liver, it is particularly important for an anesthesiologist to be familiar with hepatic pathophysiologic conditions and consequences of liver dysfunction.
In light of the impacts of fatty liver disease on the practice of anesthesia, it is critical first to screen for the presence of liver disease. The preoperative history and physical examination for patients scheduled for a procedure should include the risk factors, signs, and symptoms of liver disease 4. In addition, coagulopathy, intravascular volume, and the extra-hepatic effects of liver disease must be addressed before surgery as much as possible 5.
In liver disease, anesthetic drug distribution, metabolism and elimination may be altered—indeed the pharmacokinetics and pharmacodynamics of anesthetic drugs are significantly altered due to impaired liver function. While the uptake and onset of anesthetic drug action usually remains unaffected, hepatic clearance may be impacted. Hepatic clearance depends on the volume of distribution, functional hepatic blood flow, hepatic extraction ratio, and hepatic microsomal activity.
Since many anesthetic agents are metabolized in the liver, a recent study sought to assess the impacts of fatty liver disease on recovery from anesthesia. The single‐center, retrospective, case‐control study of adults who underwent anesthesia and concurrent abdominal imaging in a hospital setting found that patients with fatty liver suffered from delayed recovery from anesthesia. Interestingly, these results suggested that altered drug metabolism was independent of metabolic risk factors 6.
As a consequence, potent drugs like opioids may accumulate and the pharmacological actions of drugs such as benzodiazepines may be prolonged. In more extreme situations, the actions of non-depolarizing muscle relaxants such as vecuronium and rocuronium may also be prolonged, resulting in slow reversal of paralysis. Such considerations must be carefully weighed by the anesthetic team based on each individual clinical context.
Invasive monitoring tends to be recommended during major surgery 5. Close attention should further be paid to liver blood flow, renal function, encephalopathy, and the prevention of sepsis during the course of any operation 5.
Postoperative intensive care unit admission should be anticipated for patients with advanced liver disease. In certain situations, postoperative artificial ventilation may be appropriate, but in general, sedative drugs should be discontinued early and patients allowed to recover from anesthesia. In severe cases, worsening encephalopathy, jaundice, and ascites are very important clinical markers of decompensation of liver function. Invasive cardiovascular monitoring and careful fluid management should be continued to avoid the development of postoperative renal failure. In addition, coagulation should be monitored, as well as any signs of postoperative bleeding 5.
Although there remains little research focused on anesthesia in patients with fatty liver disease, it is clear that focusing on optimizing a patient’s condition preoperatively given liver dysfunction and choosing the correct anesthetic regimen and drugs for a particular clinical context is key to ensuring optimal patient safety and well-being 3.
References
1. Wong, V. W.-S., Ekstedt, M., Wong, G. L.-H. & Hagström, H. Changing epidemiology, global trends and implications for outcomes of NAFLD. J. Hepatol. (2023). doi:10.1016/j.jhep.2023.04.036
2. Mitra, S., De, A. & Chowdhury, A. Epidemiology of non-alcoholic and alcoholic fatty liver diseases. Translational Gastroenterology and Hepatology (2020). doi:10.21037/TGH.2019.09.08
3. Rahimzadeh, P., Safari, S., Reza Faiz, S. H. & Alavian, S. M. Anesthesia for patients with liver disease. Hepatitis Monthly (2014). doi:10.5812/hepatmon.19881
4. Anesthesia for the patient with liver disease – UpToDate. Available at: https://www.uptodate.com/contents/anesthesia-for-the-patient-with-liver-disease. (Accessed: 14th September 2023)
5. Vaja, R., McNicol, L. & Sisley, I. Anaesthesia for patients with liver disease. Contin. Educ. Anaesthesia, Crit. Care Pain (2009). doi:10.1093/bjaceaccp/mkp040
6. Shapses, M., Tang, L., Layne, A., Beri, A. & Rotman, Y. Fatty Liver Is an Independent Risk Factor for Delayed Recovery from Anesthesia. Hepatol. Commun. (2021). doi:10.1002/hep4.1772