1.4 Preoperative Fasting (NPO) Guidelines, Medication Management & Patient Education

Preoperative Fasting (NPO) Guidelines, Medication Management & Patient Education

Ensuring patient safety prior to anesthesia involves three core nursing pillars: enforcing evidence-based preoperative NPO (nil per os) guidelines to prevent pulmonary aspiration, managing chronic medications and herbal supplements, and delivering comprehensive preoperative patient education including informed consent verification and surgical site marking.

ASA Preoperative Fasting (NPO) Guidelines

Pulmonary aspiration of gastric contents during induction of general anesthesia can result in aspiration pneumonitis (Mendelson syndrome), severe hypoxemia, and acute respiratory distress syndrome (ARDS). The American Society of Anesthesiologists (ASA) practice guidelines establish minimum required fasting durations for healthy patients of all ages undergoing elective procedures under general anesthesia, regional anesthesia, or procedural sedation:

ASA Fasting Summary Table

Enhanced Recovery After Surgery (ERAS) Protocols

Modern ERAS protocols advocate for administering 450 mL of a 12.5% carbohydrate-rich clear drink 2 to 4 hours prior to anesthesia induction. Clear carbohydrate loading reduces preoperative thirst and anxiety, attenuates postoperative insulin resistance, preserves lean muscle mass, and decreases postoperative nausea.

High-Risk Gastric Emptying Conditions

Patients with delayed gastric emptying require extended fasting or rapid sequence induction (RSI) with cricoid pressure (Sellick maneuver). Risk factors include:

• Active Diabetes Mellitus (diabetic gastroparesis)
• Pregnancy (increased progesterone reduces lower esophageal sphincter tone)
• Morbid Obesity (BMI ≥ 40 kg/m²)
• Active Opioid Therapy or acute trauma
• Gastroesophageal Reflux Disease (GERD) or hiatal hernia

Perioperative Medication Management (Continue vs. Hold)

Systemic medications must be reviewed systematically in the preoperative clinic to determine which agents should be taken on the morning of surgery with a sip of water and which must be discontinued.

1. Cardiovascular Medications

• Beta-Blockers (e.g., metoprolol, atenolol): CONTINUE on the morning of surgery. Abrupt withdrawal causes rebound sympathetic hypersensitivity, severe hypertension, tachycardia, and perioperative myocardial infarction.
• Statins (e.g., atorvastatin): CONTINUE. Statins stabilize vascular plaque and reduce perioperative cardiac events.
• ACE Inhibitors (e.g., lisinopril) & ARBs (e.g., losartan): HOLD 24 hours prior to surgery. Continued use under general anesthesia causes refractory, severe intraoperative hypotension ("vasoplegia") unresponsive to standard adrenergic agonists like phenylephrine, requiring vasopressin administration.

2. Anticoagulants & Antiplatelets

• Aspirin: Continue for secondary prevention in patients with prior CAD or coronary stents, unless undergoing high-bleeding-risk surgery (neurosurgery, posterior eye surgery). Hold 7 days for low-risk indications.
• Clopidogrel (Plavix): Hold 5 to 7 days prior to elective surgery.
• Warfarin (Coumadin): Hold 5 days prior to surgery (target preop INR ≤ 1.5).
• Direct Oral Anticoagulants (DOACs - apixaban, rivaroxaban, dabigatran): Hold 24 to 48 hours prior to surgery depending on renal function (CrCl) and surgical bleeding risk.

3. Diabetes & Endocrine Agents

• Oral Hypoglycemics (metformin, sulfonylureas): HOLD on the morning of surgery. Metformin is held 24 to 48 hours prior if IV contrast media is administered due to lactic acidosis risk.
• Insulin: Long-acting basal insulin (NPH, glargine, detemir) is typically reduced by 20% to 50% (e.g., administer 50% of normal morning dose). Short-acting regular or lispro insulin is HELD while NPO, unless ordered as a sliding scale for hyperglycemia.
• GLP-1 Receptor Agonists (semaglutide/Ozempic/Wegovy, tirzepatide/Mounjaro): Per ASA consensus guidelines, HOLD daily GLP-1 RAs on the day of surgery, and HOLD weekly GLP-1 RAs for 1 full week (7 days) prior to elective surgery. GLP-1 agonists cause profound delayed gastric emptying, creating a high risk for residual gastric contents and pulmonary aspiration under anesthesia even after standard NPO fasting durations.

4. Herbal Supplements — The Rule of "2 Weeks"

All non-essential herbal and dietary supplements should be discontinued 2 weeks (14 days) prior to elective surgery:

• Bleeding Risk ("The 4 Gs"): Garlic, Ginkgo biloba, Ginseng, Ginger, as well as Vitamin E and Dong Quai, inhibit platelet aggregation and prolong bleeding time.
• Sedative & Anesthetic Interactions: Kava, Valerian, and St. John’s Wort potentiate GABA receptors, prolonging the sedative effects of general anesthetics. St. John's Wort also induces cytochrome P450 (CYP3A4), accelerating metabolism and reducing serum concentrations of oral contraceptives, cyclosporine, warfarin, and opioids.
• Cardiovascular Instability: Ephedra (Ma Huang) depletes endogenous catecholamines, causing intraoperative severe hypotension and dysrhythmias.

Patient Education, Informed Consent & Surgical Site Marking

Informed Consent Nursing Role

Obtaining informed consent is a non-delegable physician/surgeon responsibility. The surgeon must explain the diagnosis, proposed procedure, expected benefits, inherent risks, reasonable alternatives, and names of operating surgeons.

• Nursing Responsibility: The perioperative nurse serves as a witness to the patient's signature. The nurse verifies that:
  1. The signature is authentic.
  2. The patient possesses legal capacity and voluntary consent without coercion.
  3. The patient appears mentally competent and is not under the influence of sedating premedication.
  4. The patient confirms understanding of the procedure.
• Action if Patient Expresses Confusion: If the patient demonstrates a lack of understanding or asks detailed questions regarding risks/alternatives, the nurse must not attempt to explain the procedure; the nurse must contact the surgeon to return and re-educate the patient prior to sedation.

Universal Protocol & Surgical Site Marking

Per The Joint Commission (TJC) Universal Protocol, surgical site marking prevents wrong-site, wrong-procedure, wrong-person surgery:

• Who Marks: Marked by the licensed practitioner performing the procedure (or designated team member participating in the operation).
• When & How: Marked prior to moving the patient to the operating room, using an indelible marker that remains visible after surgical skin prep and draping.
• Patient Involvement: Performed with the active participation of the conscious, alert patient whenever possible. Initials or "YES" are preferred; never mark with an "X" (which can be interpreted as "do not operate here").

Preoperative Skin Antisepsis Education

Preoperative bathing with Chlorhexidine Gluconate (CHG) 4% soap the night before and the morning of surgery reduces skin microbial colonization (especially Staphylococcus aureus). Instruct the patient to apply CHG from the neck down, leave on skin for 1 to 3 minutes, and rinse thorough. Instruct patients never to shave the surgical site with a razor at home; razor shaving causes microscopic skin abrasions that increase SSI rates by 10-fold. If hair removal is necessary, it must be performed in the preoperative holding area using electric hair clippers with disposable heads.

Exam Traps & Clinical Pitfalls

• Exam Trap: Believing the perioperative nurse's signature on an informed consent form means the nurse explained the surgical risks. The nurse only witnesses the signature and confirms patient competence and voluntariness.
• Clinical Pitfall: Allowing a patient who took their weekly Ozempic (semaglutide) 2 days ago to undergo elective general anesthesia without alerting anesthesia. GLP-1 agonists cause delayed gastric emptying; ultrasound gastric volume assessment or rapid sequence induction may be required.