From the Guidelines
Patients should be NPO for solids for at least 6 hours and clear liquids for 2 hours before surgery. This recommendation is based on the most recent and highest quality study, which suggests that preoperative fasting from midnight is unnecessary in most patients, and that clear fluids can be consumed up to 2 hours before anesthesia, while solids can be consumed up to 6 hours before anesthesia 1. The evidence from this study, published in 2022, indicates that this approach does not increase the risk of aspiration and can help prevent preoperative fluid depletion.
Key Points
- Solid foods and non-clear liquids should be avoided for at least 6 hours before surgery
- Clear liquids, such as water, apple juice, and black coffee, can be consumed up to 2 hours before surgery
- Necessary medications can typically be taken with a small sip of water up to 2 hours before surgery, unless otherwise instructed
- Patients with specific risk factors, such as delayed gastric emptying or gastroesophageal reflux, may require different fasting instructions
- The goal of preoperative fasting is to balance the risk of aspiration with the need to prevent fluid depletion and maintain patient comfort, as supported by the ESPEN guideline 1 and other studies 1.
From the Research
Preoperative Fasting Guidelines
- The duration of preoperative fasting varies depending on the type of surgery and the patient's condition.
- According to a study published in 2014 2, the median fast from solids was 13.5 hours for elective patients and 17.38 hours for emergency patients.
- The same study found that the median fast from fluids was 9.36 hours for elective patients and 12.97 hours for emergency patients.
- However, the study also noted that the instructions given to elective patients contributed to prolonged fasting times, and that the median fast for elective patients who fully complied with fasting advice would be 10 hours for solids and 6.25 hours for clear fluids.
Recommendations for Preoperative Fasting
- A study published in 2000 3 found that most anesthesiologists practicing outpatient anesthesia in the United States had already changed their practice pattern to conform to the recent recommendations of the American Society of Anesthesiologists task force on preoperative fasting time.
- These recommendations suggest that healthy adults undergoing elective surgery can have clear liquids up to 2-3 hours before the induction of anesthesia and a light breakfast up to 6 hours before elective surgery.
- Another study published in 1999 4 found that patients with jejunostomy tubes can be fed safely until the time of surgery, and that stopping tube feedings for at least 8 hours before surgery is not necessary.
Current Practices and Guidelines
- A literature review published in 2020 5 found that actual fasting time is often relatively longer than prescribed fasting times, and that anaesthetists possess greater knowledge of reduced preoperative fasting than other health professionals.
- The same review noted that new guidelines recommend that patients remain nil by mouth from clear fluids for 2 hours and from solids for 6 hours before elective surgery.
- Another study published in 2020 6 emphasized the importance of providing preoperative care that prepares patients to undergo surgery safely, but did not provide specific guidelines for preoperative fasting.