Is it time to rethink fasting times in the emergency department?

Chumpitazi, CE, Camp, EA, Bhamidipati, DR, et al. “Shortened Preprocedural Fasting in the Pediatric Emergency Department.” The American Journal of Emergency Medicine, vol. 36, no. 9, 2018, pp. 1577–1580.

The relationship between pre-procedural fasting times and aspiration and/or pulmonary complications are often a topic in anesthesia and sedation literature. In particular, fasting or nil per os (NPO) guidelines for urgent procedures outside of the operating room continue to be vague.  Prolonged fasting times can often be difficult for both emergency providers and families to manage. The American Society of Anesthesiologists (ASA) guidelines focus on 2 hours of fasting for clear liquids and up to 8 hours for full fatty meals. The American College of Emergency Physicians (ACEP) states that procedures in the emergency department (ED) setting should not be delayed based on fasting times alone. Many studies looking specifically at fasting times and adverse events often are under-powered, or may not focus specifically on patients in the ED setting. 

The 2018 study by Chumpitazi, et al, describes aspiration rates and rates of vomiting in patients with shortened pre-procedural fasting times. Patients requiring urgent procedures within this study cohort were shortened from a fasting time of 8 hours for a full meals and 6 hours for a snack to 3 hours for both meals and snacks. Clear liquid fasting requirements were shortened to zero hours. Procedure type, demographic data, NPO times and length of procedure were studied in addition to vomiting rates. 

2188 patients were included in this study. 1472 were in a “standard fast group” and 716 in a “shortened” fast group. Only 98 patients vomited and there were no reported cases of aspiration. Results for patients with shortened fast times showed that ketamine only, as a single sedation agent, was primarily used in ~83.5% of cases. Fracture reduction was the most common sedated procedure (29.9% of patients in the shortened fast group) followed by incision and drainage of an abscess (29.2%). The average length of emergency department stay was 7 hours in patients who fasted a shortened length of time, compared to 7.6 hours for patients who fasted at the standard length of time. 

Given this, is NPO time itself an independent risk factor for aspiration? The authors raise the question in their discussion. They state that independent factors such as ASA class II or higher and age less than one year appear to be more predictive of adverse outcomes. Additionally, the authors make the point that due to already existing ED wait times, patients requiring sedation are already fasted well beyond 3 hours, with ED length of stays that approach 7 hours in many cases. This appears to be the same for both the standard and shortened fasting groups. There are several limitations to this study.  Although data was collected at one of the largest pediatric EDs in the country, the study still represents data from a single center with results that may not be generalizable to other institutions. Second, while data was prospectively collected, fasting data was missing for ~10% of all patients.   Overall, it appears that a shortened pre-procedural fasting time, namely with ketamine does not appear to increase overall rates of vomiting in the ED.

Carmen D. Sulton, MD