Preoperative clear fluid fasting in patients undergoing nonemergency liver transplant: duration, hemodynamic and metabolic correlates. A prospective observational single-centre study
In a prospective observational study of 99 liver transplant recipients, preoperative clear fluid fasting was found to be substantially longer than the recommended 2-hour guideline, yet its duration showed no significant association with metabolic derangements or conclusive links to post-induction hypotension, highlighting a gap between practice and guidelines while underscoring the need for larger studies to clarify clinical consequences.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Before a major surgery, patients are told to stop eating and drinking for a certain amount of time. This rule exists to keep the stomach empty, reducing the risk that food or liquid could be breathed into the lungs while the patient is asleep. For decades, the standard advice was to stop all intake after midnight, but modern guidelines have softened this. Experts now say that clear liquids, like water or apple juice, can be safely consumed up to two hours before anesthesia. This change is based on the idea that the stomach empties these fluids quickly, leaving the patient hydrated and more comfortable without increasing danger. However, for patients waiting for a liver transplant, the situation is more complicated. These individuals often have severe liver disease, which can slow down how fast their stomachs empty and change how their bodies process energy. Because of this, it has been unclear whether the standard two-hour rule applies to them, or if the chaotic nature of transplant surgery—where organs arrive at unpredictable times—forces them to wait much longer.
A team of researchers at the Medical University of Warsaw in Poland decided to investigate this gap between official rules and real-world practice. They focused on adults undergoing non-emergency liver transplants, a group that is medically fragile and at high risk for sudden drops in blood pressure when anesthesia is started. The researchers wanted to know two things: how long these patients actually went without drinking clear fluids before their surgery, and whether that waiting time caused any immediate harm, such as a drop in blood pressure or changes in blood sugar and acid levels. They followed 99 patients who were scheduled for a transplant from a deceased donor. As each patient arrived in the operating room, the team recorded exactly when they last had a drink. They then monitored the patients closely during the induction of anesthesia, checking their blood pressure every few minutes and testing their blood for signs of metabolic stress.
The results revealed a significant disconnect between the guidelines and what actually happened in the operating room. While the rules suggest patients should drink up until two hours before surgery, the typical patient in this study waited twelve hours. Only three out of the 99 patients managed to drink within the recommended two-hour window. The vast majority waited much longer, with many going more than sixteen hours without a sip of water. This long wait was not due to a medical necessity but rather the logistical reality of transplant surgery, where the arrival of a donor organ is often unpredictable, leaving patients fasting while waiting for the call.
The researchers then looked to see if this extended fasting caused the feared complications. They examined whether the length of the fast made patients more likely to experience a sudden drop in blood pressure when the anesthesia drugs were first given. They also checked if longer fasting led to new problems with blood sugar, lactic acid, or acid-base balance during the surgery. The data showed no clear link between how long a patient fasted and these negative outcomes that met the study's strict statistical criteria. However, the analysis did reveal a signal suggesting that longer fasting might actually be associated with slightly lower odds of a blood pressure drop, though this finding was not statistically robust enough to be considered definitive. Patients who waited twelve hours did not have significantly different metabolic changes compared to those who waited less time.
Despite these findings, the authors are careful not to suggest that doctors should keep patients fasting longer. The study was designed to observe what was happening, not to prove that long fasting is safe or beneficial. The lack of a negative result does not mean that the two-hour rule is wrong; it simply means that in this specific group of patients, the extra hours of waiting did not appear to cause the specific problems the researchers were looking for. The study highlights a major issue in patient care: people are being made to wait far longer than necessary, which increases thirst and anxiety, without any clear medical benefit. The researchers conclude that while the current guidelines remain the standard, the real-world practice of forcing liver transplant patients to fast for many hours needs to be addressed through better communication and planning, rather than assuming that longer fasting is required for safety.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.