Why do you need to stop eating 24 hours before surgery?

It is generally recommended to stop eating for at least 8-12 hours before surgery, rather than 24 hours. This is primarily done for safety reasons during general anaesthesia. Here's why:

1. Aspiration Risk: During general anaesthesia, the muscles that control swallowing and airway protection may be relaxed. This can increase the risk of aspiration, which is the accidental passage of stomach contents (food, liquids) into the lungs. Food particles or liquids in the stomach can cause choking, coughing, and potentially lead to pneumonia if they enter the lungs. By fasting beforehand, the stomach is relatively empty, reducing the risk of aspiration during and after surgery.

2. Delayed Gastric Emptying: Certain medications used during anaesthesia can slow down the emptying of the stomach. This delay can persist for several hours after the surgery. Having food in the stomach during this time can further delay gastric emptying and increase the risk of aspiration.

3. Nausea and Vomiting: After surgery, some patients experience nausea and vomiting due to the effects of anaesthesia, pain medications, or other factors. An empty stomach minimizes the chances of vomiting and reduces the risk of inhaling stomach contents during this period.

4. Electrolyte Imbalances: Electrolyte imbalances can occur if patients drink excessive amounts of water before surgery. While staying hydrated is important, clear fluids or specific preoperative drinks are typically recommended in the hours leading up to surgery to maintain fluid balance.

5. Clear Surgical Field: An empty stomach can provide a clearer surgical field for the surgeon, allowing for better visibility and potentially reducing the risk of complications during the procedure.

6. Postoperative Recovery: An empty stomach can facilitate a smoother and faster recovery after surgery. Nausea, vomiting, and other postoperative complications may be reduced by minimizing the risk of aspiration and other issues related to food in the stomach.

It's essential to follow the fasting instructions provided by your doctor or anaesthetist before surgery to ensure your safety during the procedure and your subsequent recovery.