fasting before procedural sedation
We have comprehensively reviewed the literature evidence relating to fasting and aspiration, and have used our consensus methodology to develop the first fasting and aspiration prevention recommendations specific to procedural sedation:
- An international multidisciplinary consensus statement on fasting before procedural sedation in adults and children. Anaesthesia 2020; 75:374-385.
Download a PDF of the fasting algorithm here.
Evidentiary summary conclusions
Question 1: Is there a difference in the incidence and outcome of pulmonary aspiration events in patients who receive general anesthesia and those who receive procedural sedation, and are the associated risks different between the two?
- Aspiration associated with general anesthesia is rare, with reasonable point estimates for its incidence—in aggregate samples and before consideration of risk factors—of 1:7,103 for adults and 1:4,800 for children, and reasonable point estimates of its resulting mortality of 1:78,732 for adults and <1:334,856 for children. (Quality of evidence: High)
- Aspiration associated with procedural sedation is rare, with the best available point estimate of its incidence 1:13,914 in a pediatric study. There are only nine reports of aspiration-associated deaths in the post-1984 medical literature, of which eight were during upper endoscopy. None occurred in children or in healthy adults. (Quality of evidence: High)
- The risk of aspiration during procedural sedation appears to be well under half that of general anesthesia, and the risk of aspiration-related death from procedural sedation (particularly non-endoscopic) appears to be substantially less than that with general anesthesia. (Quality of evidence: High)
Question 2: What are the known risk factors for pulmonary aspiration with general anesthesia and with procedural sedation?
- Esophageal endoscopy presents higher aspiration risk than other sedation procedures in adults (Quality of evidence: High) and likely children (Quality of evidence: Moderate).
- Greater underlying illness presents higher aspiration risk during procedural sedation in adults (Quality of evidence: High) and possibly in children (Quality of evidence: Low).
- Sedation for emergency procedures is not an identified risk factor for aspiration—unlike emergency anesthesia. (Quality of evidence: High)
Question 3: What is the evidence that fasting prior to general anesthesia or procedural sedation improves outcomes?
- There is no observed association between aspiration and non-compliance with typical fasting guidelines, either for general anesthesia or for procedural sedation, and in either adults or children. (Quality of evidence: Moderate)
- Regurgitated clear liquids appear to represent little or no risk of aspiration morbidity. (Quality of evidence: High)
- Imaging has frequently identified gastric fluids and solids in pre-operative patients compliant with existing fasting guidelines, indicating that general anesthesia is regularly and widely performed in patients whose stomachs are not empty. (Quality of evidence: High)
- Liberalized pre-anesthesia fasting in recent decades has not been associated with an increase in aspiration frequency. (Quality of evidence: High)
- There are multiple settings outside of the operating room which have been regularly non-compliant with typical fasting guidelines for decades, and without evidence of increased aspiration risk. (Quality of evidence: Moderate)
Question 4: Does pre-anesthesia and pre-sedation fasting negatively impact patient comfort, patient health, the anesthesia or sedation experience, or workflow?
- In clinical practice minimum fasting thresholds are often substantially exceeded. (Quality of evidence: High)
- Fasting is uncomfortable and, in children particularly, can lead to irritability, impaired cooperation, dehydration, hypoglycemia, and increased sedation failure. (Quality of evidence: High)
Question 5: What is the impact of published guidelines and clinical strategies for pre-operative or pre-procedural care (including fasting) on the prevention of pulmonary aspiration?
- There is no confirmation that specific strategies (including pre-procedural fasting) have a clinically important impact in preventing pulmonary aspiration. (Quality of evidence: Moderate)
Question 6: Are there barriers to the development of fasting recommendations for procedural sedation that differ from existing guidelines designed for general anesthesia?
- The longstanding precedent of guidelines stipulating that sedation fasting precautions be identical to those for general anesthesia presents challenges and barriers to clinicians and institutions wishing to clinically apply evidence of decreased aspiration risk with procedural sedation. (Quality of evidence: High)
Guiding principles for statement recommendations
Summary perspectives from general anesthesia
- Aspiration associated with general anesthesia is now extremely rare. When it does occur, it is frequently associated with airway maneuvers, e.g., tracheal intubation, extubation.
- Fasting does not guarantee an empty stomach. Research has verified that fasting-compliant patients sent for general anesthesia commonly have intra-gastric fluids and solids and, thus, anesthesia is—and likely always has been—regularly and widely administered to those with appreciable gastric contents.
- Regurgitated clear liquids appear to present no meaningful risk of clinically important aspiration morbidity or mortality.
Summary perspectives from both general anesthesia and procedural sedation
- Specific literature-identified factors predict patients at higher risk of aspiration.
- Fasting, as currently practiced, often substantially exceeds recommended time thresholds and has known adverse consequences, e.g., irritability, dehydration, hypoglycemia.
- There is no observed association between aspiration and compliance with common fasting guidelines.
Procedural sedation synthesis
- The probability of clinically important aspiration during procedural sedation is negligible. In the post-1984 literature there are no published reports of aspiration-associated mortality in children, no reports of mortality in healthy adults (ASA I or II), and just 9 reported deaths in adults ASA III or greater. Current concerns regarding aspiration vastly exceed the actual risk.
- Given the lower frequency of aspiration and mortality as compared to general anesthesia and the theoretical basis for lesser risk, fasting strategies in procedural sedation can reasonably be less restrictive.