What is the risk of aspiration if I drink a little water 2 hours before general anesthesia surgery?

From the Guidelines

Drinking a small amount of water 2 hours before general anesthesia poses minimal risk of aspiration for most healthy patients. According to the most recent and highest quality study, 1, current guidelines from anesthesiology societies generally consider clear liquids (including water) safe up to 2 hours before elective surgery. The stomach typically empties clear liquids within 1-2 hours, so water consumed 2 hours prior should have passed through your stomach by the time anesthesia begins.

Key Points to Consider

• Aspiration risk occurs when stomach contents can potentially enter your lungs during anesthesia, but clear liquids like water are rapidly absorbed and don't increase stomach volume significantly after this timeframe.
• Certain conditions like diabetes, obesity, pregnancy, or gastrointestinal disorders can delay stomach emptying and may require longer fasting periods.
• It is essential to follow specific pre-operative instructions from your anesthesiologist or surgeon, as individual circumstances may vary.
• The ESPEN practical guideline, 1, recommends that patients undergoing surgery, who are considered to have no specific risk of aspiration, shall drink clear fluids until 2 hours before anesthesia, with a strong consensus (97% agreement) and grade of recommendation A.

Important Considerations

• If you're uncertain about your particular situation, contact your healthcare provider for personalized guidance rather than making assumptions about fasting requirements.
• The implementation of these guidelines has not reported a dramatic rise in the incidence of aspiration, regurgitation, or associated morbidity or mortality, as stated in 1.
• Avoidance of fasting is also a key component of Enhanced Recovery After Surgery (ERAS), allowing intake of clear fluids, including coffee and tea, to minimize discomfort and headaches from withdrawal symptoms, as mentioned in 1.

From the Research

Risk of Aspiration with Preoperative Water Intake

• The risk of aspiration when drinking a little water 2 hours before general anesthesia surgery is considered low, according to studies 2, 3.
• A study published in the Canadian Journal of Anesthesia found that drinking 300 mL of clear fluid two hours before surgery had no effect on gastric fluid volume and pH in fasting and non-fasting obese patients 3.
• Another study suggested that clear liquid ingestion up to two hours before induction of anesthesia in healthy patients without risk factors is safe and does not increase the risk of pulmonary aspiration 2.
• The American Society of Anaesthesiologists (ASA) physical status score, emergency surgery, difficult airway management, and other factors can increase the risk of pulmonary aspiration, but these are not directly related to the timing of water intake 2, 4.

Guidelines for Preoperative Fasting and Fluid Intake

• The traditional nil per os (NPO) order for clear fluids and solids overnight or six to eight hours preceding the induction of anesthesia may be unnecessary for patients without risk factors 2.
• Liberalized guidelines for preoperative fasting and fluid intake have been shown to decrease discomfort, irritability, anxiety, thirst, and hunger in the perioperative period without increasing the risk of pulmonary aspiration 2.
• A study published in the Journal of Anesthesia reported a case where a patient drank 600 ml of a soft drink 2 hours before surgery and absorbed nearly all of it within the 2 preoperative hours, suggesting that 2 hours may be sufficient for preoperative fasting after soft drink intake 5.

Prevention of Regurgitation and Aspiration

• The use of parenteral and enteral antacids as premedication in urgent surgery can help prevent regurgitation and aspiration under general anesthesia 6.
• A protocol for patient preparation for general anesthesia in urgent surgery has been developed, which includes the use of antacids and other measures to reduce the risk of aspiration 6.
• Rapid sequence induction and intubation (RSI) can be an effective way to prevent pulmonary aspiration in patients at risk, and should be performed by experienced anesthesiologists with adequate equipment and monitoring 4.