Does decreasing NPO for clear fluids to 1 hour increase the incidence of adverse respiratory events?
Myron Yaster MD, Libby Elliott MD, and Francis Veyckemans MD
Should the current clear liquid fasting period remain 2-hours or be reduced to one? We’ve discussed this issue several times in previous PAADs (09/14/2021 https://ronlitman.substack.com/p/npo-for-clear-liquids-star-wars-edition and 07/ 19/2021 https://ronlitman.substack.com/p/npo-guidelines-are-they-bubbameisters ) and concluded that the 2 hour fasting guideline for clear liquids was not supported by evidence and that a 1 hour fast was reasonable.1-4
In today’s PAAD, Schmitz et al.5 performed a large prospective, observational, multi-institutional cohort study in Switzerland to investigate the incidence of adverse respiratory events after implementing a new, national, 1 hour fast recommendation in children. Myron Yaster MD
Original article
Schmitz A, Kuhn F, Hofmann J, Habre W, Erb T, Preuss M, Wendel-Garcia PD, Weiss M, Schmidt AR. Incidence of adverse respiratory events after adjustment of clear fluid fasting recommendations to 1 h: a prospective, observational, multi-institutional cohort study. Br J Anaesth. 2024 Jan;132(1):66-75. doi: 10.1016/j.bja.2023.10.009. Epub 2023 Nov 11. PMID: 37953199.
Because general anesthetics blunt or abolish protective airway reflexes, pre‐operative and pre-procedural fasting is employed to minimize gastric content and volumes and in turn, decrease the risk of pulmonary aspiration. By and large fasting guidelines appear to have worked.6 Aspiration during elective anesthesia is extremely rare, however, and our current concerns about aspiration may be out of proportion to the actual risk, particularly for clear liquids. Indeed, several national societies, but not the ASA,7 have published consensus statements encouraging 1-h fasting times for clear fluids in children.1,3,8 In fact, the parents are invited/encouraged to give small amounts of clear fluids up to one hour before the induction of anesthesia, avoiding forcing their child to drink.
“The Swiss Society of Paediatric Anaesthesia (SSPA) decided in 2018 to recommend a 1-h fasting time for clear fluids for children. This statement was endorsed by the Swiss Society of Anaesthesiology and Perioperative Medicine (SSAPM) and recommends a maximum volume 3 mL/kg of non-thickened and non-carbonated clear fluid (water, clear [non-opaque] fruit juice, ready diluted drinks, and non-fizzy sport drinks). The aim of today’s prospective, observational, multiinstitutional cohort study was therefore to investigate the incidence of pulmonary aspiration, gastric regurgitation, and vomiting after implementing the nationally recommended 1-h fasting instructions for clear fluids among various Swiss hospitals and office-based anaesthesia providers where anesthesia is performed on pediatric patients. All patients aged 0 to 15 yr undergoing general anaesthesia for an elective procedure who had received fasting instructions of 1 h for clear fluids were included in this audit.”5 “The primary outcome was the perioperative (defined as the time from anesthesia induction to emergence) incidence of pulmonary aspiration, gastric regurgitation, and vomiting.”5
Ok, what did they find? “From June 2019 to July 2021, 22,766 anesthetics were recorded with pulmonary aspiration occurring in 25 (0.11%), gastric regurgitation in 34 (0.15%), and vomiting in 85 (0.37%) cases. Most aspiration events occurred during induction (40%), followed by awakening (28%). No major morbidity or mortality was associated with pulmonary aspiration. Subgroup analysis by effective fasting times (<2h [n=7306] vs > 2h [n=14 660]) showed no significant difference for pulmonary aspiration rates between these two groups (9 [0.12%] vs 16 [0.11%], p=0.678). Median effective fasting time for clear fluids for the total population was 157 [104-314; 2-2385] min, 753.0 min for solids [445-875, 225-2273], and 310 min [266-396; 185-2186] min for milk. In the 7306 children in whom a fasting less than 2h was effectively achieved, the median time was 89 min [70-104; 2-119]. Schmitz et al. conclude that “Implementing a national recommendation of 1-h clear fluid fasting was not associated with a higher incidence of pulmonary aspiration compared with previously reported data.”5
Another finding was that in spite of 1-h prescription for clear fluids, a fasting time less than 2h was achieved in only a third of the participating children. However, using a 1-h clear fasting instruction reduces the median effective fasting time to 157 min. This is a clear improvement with respect to prolonged fasting, as can be seen from published data using a 2-h fasting instruction for clear fluid. As the risk of pulmonary aspiration is similar for 1 h and 2 h of clear fluid fasting this study supports the preoperative fasting guidelines for children of the ESAIC,1
There is abundant published data indicating that 1 hour fasting policies are safe and well tolerated in children. In the U.S., making the change to a 1 hour clear liquid fast will be hindered until the ASA changes its guideline recommendations. In all countries change will be hampered by inertia and by the idea “if it ain’t broke why fix it?” At an editorial level, the PAAD executive council has realized the need to review not only quality improvement studies (and the journals that publish them) but also the equally important need to look at implementation science articles and journals. In other words how do you get change, like a 1 hour fast, implemented into everyone’s practice? To that end, Dr. Lynn Martin has assembled a team to do just that. So, keep your eyes open as we open an entirely new dimension of articles that will be reviewed in the PAAD.
Finally, Hurricane Helene decimated the Baxter plant in North Carolina, which supplies over half of the IV fluid in the United States. Communications with Wake Up Safe sites have shown that most providers are being asked to limit or ration which patients receive IV fluid and the volumes they receive. Given the fact that oral hydration is effective and well tolerated, and IV fluid is limited have you changed your policies to allow a one hour clear fluid fast? Are you concerned that maintaining the 2 hour limit in light of the recent IV fluid shortage is potentially harmful to patients? If you are changing your policies, what obstacles did you have to overcome? Send your thoughts and comments to Myron who will post in a Friday reader response.
References
1. Frykholm P, Disma N, Andersson H, et al. Pre-operative fasting in children: A guideline from the European Society of Anaesthesiology and Intensive Care. European journal of anaesthesiology 2022;39(1):4-25. (In eng). DOI: 10.1097/eja.0000000000001599.
2. Vutskits L, Davidson A. Fluid Fasting in Children: Solid Science? Anesthesiology 2020;133(3):493-494. (In eng). DOI: 10.1097/aln.0000000000003406.
3. Green SM, Leroy PL, Roback MG, et al. An international multidisciplinary consensus statement on fasting before procedural sedation in adults and children. Anaesthesia 2020;75(3):374-385. (In eng). DOI: 10.1111/anae.14892.
4. Lee JJ, Price JC, Duren A, et al. Ultrasound Evaluation of Gastric Emptying Time in Healthy Term Neonates after Formula Feeding. Anesthesiology 2021;134(6):845-851. (In eng). DOI: 10.1097/aln.0000000000003773.
5. Schmitz A, Kuhn F, Hofmann J, et al. Incidence of adverse respiratory events after adjustment of clear fluid fasting recommendations to 1 h: a prospective, observational, multi-institutional cohort study. British journal of anaesthesia 2024;132(1):66-75. (In eng). DOI: 10.1016/j.bja.2023.10.009.
6. Habre W, Disma N, Virag K, et al. Incidence of severe critical events in paediatric anaesthesia (APRICOT): a prospective multicentre observational study in 261 hospitals in Europe. Lancet Respir Med 2017;5(5):412-425. (In eng). DOI: 10.1016/s2213-2600(17)30116-9.
7. Joshi GP, Abdelmalak BB, Weigel WA, et al. 2023 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting: Carbohydrate-containing Clear Liquids with or without Protein, Chewing Gum, and Pediatric Fasting Duration-A Modular Update of the 2017 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting. Anesthesiology 2023;138(2):132-151. (In eng). DOI: 10.1097/aln.0000000000004381.
8. Linscott D. SPANZA endorses 1-hour clear fluid fasting consensus statement. Pediatric Anesthesia 2019;29(3):292-292. DOI: https://doi.org/10.1111/pan.13585.