From the Guidelines
Patients undergoing surgery with general anesthesia should fast from solid foods for 6 hours and clear liquids for 2 hours before the procedure, except for medications which can be taken with a small sip of water up to 2 hours before surgery. This recommendation is based on the most recent and highest quality study available, which suggests that preoperative fasting from midnight is unnecessary in most patients 1. The guidelines aim to reduce the risk of pulmonary aspiration during anesthesia by ensuring the stomach is relatively empty, while also considering the patient's comfort and reducing the risk of dehydration.
Some key points to consider include:
- Stopping solid foods 6 hours before surgery
- Discontinuing clear liquids 2 hours before surgery
- Allowing medications to be taken with a small sip of water up to 2 hours before surgery
- Considering individual patient needs, such as diabetic patients who may require special instructions regarding medication timing and glucose monitoring
- Following specific instructions provided by the surgical team, as requirements may vary based on individual health conditions and procedure type
It's worth noting that the traditional "midnight NPO" rule has been modified, and evidence shows that prolonged fasting can lead to dehydration and increased patient discomfort without improving safety 1. The most recent guidelines recommend a more flexible approach to preoperative fasting, taking into account the type of surgery, the patient's health status, and the risk of aspiration 1.
From the Research
NPO Guidelines for Patients Undergoing Surgery or Procedures Requiring General Anesthesia
- The guidelines for NPO orders have been revised to reduce the duration of pre-procedural fasting, as evidence suggests that the risk of aspiration is low 2, 3.
- Current guidelines support a reduced fasting duration before procedures necessitating anesthesia or sedation, but many health systems still use NPO past midnight 2.
- A quality improvement initiative at a single academic health system in Southeast Texas aimed to reduce the use of NPO past midnight by 50% within 6 months and was successful in reducing NPO past midnight usage to only 33% of pre-procedural diet orders 2.
- Surgery remains the most common indication for continued use of NPO, and aspiration events and procedural delays were rare 2.
- Liberal approaches allowing clear fluids up to 1 hour prior to anesthesia or until premedication/call to the operating room have shown no increase in adverse events among children, and similar reports in the adult cohort are scarce 3.
Medication Management During NPO
- The decision to continue or stop antihypertensive medications during the perioperative period is crucial to ensure patient safety, and current evidence supports the perioperative continuation of β-blockers, calcium-channel blockers, and α-2 agonists 4.
- Diuretics should be discontinued on the day of the surgery and resumed in the postoperative period, and debates persist about the continuation of renin-angiotensin-aldosterone system inhibitors 4.
- Anesthesiologists should have a working knowledge of the systemic implications of hypertension and the common medications used in the treatment of hypertension, including diuretics, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and renin-inhibiting agents 5.
Exceptions to NPO
- Medications, especially those related to hypertension management, may be continued during the NPO period, but the decision should be made on a case-by-case basis 4, 5.
- The use of multimodal general anesthesia strategies, which include the administration of different drugs together to create the anesthetic state, may also affect NPO orders and medication management 6.