Preoperative Fasting in Infants and Children Janey Phelps

Preoperative Fasting in Infants and Children Janey Phelps, MD, FAAP University of North Carolina, Chapel Hill Children’s Hospital

Disclosures No relevant financial relationships

Learning Objectives: • Review history of NPO guidelines • Review current ASA NPO guidelines • Review controversial cases

History of Aspiration During Anesthesia 1853 • Soldier in Burma vomited during surgery for a gunshot wound to the thigh • Autopsy showed that trachea was “filled with vomited matters” 1862 • 1 st case report of death during anesthesia from inhalation of gastric contents 1940 • Charles Hall described 15 cases of aspiration in obstetric patients • 5 of the 15 patients died 1945 • Curtis Mendelson describes 66 cases of aspiration of stomach contents out of 44, 016 obstetric cases

Mendelson Syndrome • In addition to the case series, Mendelson conducted research on adult rabbits • 2 distinct Syndromes - Aspiration of solid material - Aspiration of liquid material

Mendelson Syndrome (con’t) Recommendations to prevent aspiration • NPO • Regional versus general anesthesia • Alkalinizing the stomach contents • Competent administration of anesthesia • Adequate equipment

History of NPO orders • 1 st book on anesthesia did not mention fasting 1847 • Fasting was to minimize unpleasantness of emesis • Sir Joseph Lister published fasting guidelines 1883 • Distinguished between solid meals and liquid 1947 • Synopsis of Anaesthesia advocated for no food within 6 hours of anesthesia • NPO after midnight 1960 • Children NPO solid and milk for 6 hours, liquids for 2 hours (Cohen 1970) • Roger Maltby, University of Calgary: randomized controlled trials to determine residual gastric volume (RGV) 1985 • Reduction of RGV in drinking groups (clears up to 3 hours) vs fasted groups (solids) 1990 • ASA NPO guidelines

Critical Gastric Volume • Gastric volume exceeds 25 ml with p. H < 2. 5 in 4080% of healthy patients who fasted for at least 8 hours • Human stomach is very distensible and can accommodate up to 1000 ml before intra-gastric pressure increases • 1986 Plourde and Hardy demonstrated in cats that gastric volume > 21 ml/kg was required to produce regurgitation while under ketamine anesthesia

Pulmonary Aspiration • 1985 -1992: 215, 488 general anesthetics reviewed for pulmonary aspiration - Bilious secretions or solid matter in tracheobronchial tree - Presence of new infiltrate on postop chest X-ray • • ASA 1 & 2 Elective surgeries: 1/8000 ASA 4 & 5 Emergency surgeries: 1/343 ~ 75 - 80% occurred during induction Mortality was 1/71, 829 Warner etal, Anesthesiology 1993

Pulmonary Aspiration and Pediatrics Pediatric Sedation Research Consortium (PSRC) database • 42 participating institutes • Reviewed 139, 142 sedation/anesthesia encounters from 2007 - 2011 • 10 cases of aspiration (8 of these patients were appropriately NPO (>2 hours for clears, >6 hours for solids) • No relationship between NPO interval and adverse pulmonary events • Positive correlation between ASA status > 2, emergency sedation status, and young age Beach ML, etal. Anesthesiology 2012.

Analysis of Aspiration Event Versus NPO for Solids Duration of NPO (solids) Total Cases Aspiration Event < 2 hrs 659 0 2 hrs 798 0 4 hrs 4, 208 0 6 hrs 23, 421 5 >8 hrs 100, 559 1 unknown 2, 127 0 Total 131, 772 6 5, 665 NPO 4 hours or less for solids with no aspiration event Beach ML, etal. Anesthesiology 2012.

ASA Guidelines for Preoperative Fasting • Revised in 2011 • Intended patient population for these guidelines are limited to healthy patients of all ages undergoing elective procedures • Not intended for women in labor • Intended for general anesthesia, regional anesthesia, or sedation/analgesia (MAC) • Following guidelines does not guarantee complete gastric emptying

ASA Guidelines for Preoperative Fasting • Clear liquids 2 hours - Examples water, fruit juices without pulp, carbonated beverages, clear tea, and black coffee - No alcohol - Volume is less important than type • • Breast milk 4 hours Infant formula 6 hours Light meal and nonhuman milk 6 hours Fried or fatty foods 8 hours

How many hours are required for NPO status requiring Oral contrast for CT scan? 1) 2) 3) 4) 5) 2 hours 4 hours 6 hours 8 hours negligible

Oral Contrast: Current Practices and Controversies • Goal is to obtain CT scan within 1 hour of contrast • Emptying of clear liquids is proportional to the volume present • Small bowel transit time - As fast as 15 minutes - Average 84 minutes - 83% is < 120 minutes Mahmoud M etal, Pediatric Radiology 2011.

Gastric emptying time of Oral Contrast • 101 patients, 3 – 18 years of age • Contrast enhanced abdominal CT - Acute appendicitis n=90 - Abdominal trauma n=10 - Suspected ileus n=1 • < 40 kg: 500 ml of contrast • > 40 kg: 750 ml of contrast • Senior radiologist reviewed scans to estimate gastric emptying times (GET) Berger-Achituv S etal, Gastroenterology 2010.

Gastric emptying time of Oral Contrast • Results of OCM in stomach - 75% at 48 +/- 5. 2 minutes - 50% at 74 +/- 7. 5 minutes - 25% at 135 +/- 32. 5 minutes • Mean time to drink OCM: 105. 1 +/- 27. 9 minutes Conclusion: advocate waiting minimum 3 hours after ingestion of OCM and GA

Ask the Experts 18 pediatric anesthesiologists: 5 Bowman Gray, 5 Duke and 8 UNC • 27. 8% have practiced < 5 years • 16. 6% have practiced 5 - 10 years • 55. 6% have practiced > 10 years • 72. 2% have > 5 years experience as a pediatric anesthesiologists

How many hours are required for NPO status requiring PO contrast for CT scan? Attendings 70. 00% 60. 00% 50. 00% 40. 00% 30. 00% 20. 00% 10. 00% 2 hours 4 hours 6 hours 8 hours negligible

How many hours are required to meet NPO status for hard candy? 1) 2) 3) 4) 5) 2 hours 4 hours 6 hours 8 hours negligible

How many hours are required to meet NPO status for hard candy? Attendings 70. 00% 60. 00% 50. 00% 40. 00% 30. 00% 20. 00% 10. 00% 2 hours 4 hours 6 hours 8 hours negligible

Parent’s Compliance with NPO Orders 120 Parents completed a survey after outpatient surgery Reasons for fasting Aspiration N&V Efficacy of Anesthesia Other Cantellow S et al. Pediatric Anesthesia 2012.

Parent’s Compliance with NPO Orders 9 8 7 6 5 4 3 2 1 0 Advised fasting times (median) Actual fasting times (median) clears solids • 13. 5% were out of compliance based on survey results • Increased fasting times places patients at risk for dehydration, especially if surgery is delayed Cantellow S etal, . Pediatric Anesthesia 2012.

Considerations • Some institutions in US are using 1 hour NPO for clears in children even though ASA recommendations are currently 2 hours • Point of Care Ultrasound (POCUS) can be used to determine gastric volume and may change how NPO guidelines are viewed in the future

Conclusions: • Although rare, aspiration pneumonia can lead to death • Adhering to NPO guidelines does not always prevent aspirations • All elective cases should adhere to ASA NPO guidelines - 2 hours clears 4 hours breast milk 6 hours formula/light meal 8 hours fatty or full meals • If patient has a full stomach and it is an emergency, perform a rapid sequence intubation

References: • Roberts and Shirley. Reducing the risk of gastric aspiration during cesarean section. Anesthesia and Analgesia. 1974; 53: 859 -868. • Warner MA, Warner ME, Weber JG. Clinical significance of pulmonary aspiration during the perioperative period. Anesthesiology. 1993; 78: 56 -62. • Beach ML, Cohen DM, Gallagher SM, Cravero JP. Major Adverse Events and Relationship to Nil per Os Status in Pediatric Sedation/Anesthesia Outside the Operating Room: A Report of the Pediatric Sedation Research Consortium. Anesthesiology. 2016 Jan; 124(1): 80 -8. • Keeter S, Benator RM, Weinberg SM etal. Sedation in pediatric CT: National survey of current practice. Radiology. 1990; 175: 745 -752. • Mahmoud M, Mc. Auliffe J, Donnelly L. Administration of enteric contrast material before abdominal CT in children: current practices and controversies. Pediatric Radiology. 2011; 41: 409 -412. • Berger-Achituv S, Zissin R, Shenkman Z, et al. Gastric emptying time of oral contrast material in children and adolescents undergoing abdominal computed tomography. Gastroenterology. 2010; 51: 31 -34. • Cantellow S, Lightfoot J, Bould H, Beringer R. Parents’ understanding of and compliance with fasting instructions for pediatric day case surgery. Pediatric Anesthesia. 2012; 22: 897 -890.