Clinics in Medical Education

CLINICAL

Pulmonary Aspiration During Anesthesia: Is the Incidence Truly Increasing, or Are We Finally Measuring It Better?

Miguel Magallanes, MD
Federico Puerta Martinez, MD

Issue 3 | Volume 2 | August 2026

KEY TAKEAWAYS

  1. Aspiration remains rare, but its true incidence is uncertain: Differences in definitions, recognition, documentation, and surveillance make perioperative pulmonary aspiration difficult to measure accurately. 
  2. Delayed gastric emptying does not equal aspiration: GLP-1 receptor agonists are associated with increased residual gastric contents, yet current evidence has not demonstrated a corresponding increase in documented pulmonary aspiration. 
  3. We may be detecting risk better, not necessarily seeing more aspiration: Greater awareness, improved reporting, and tools such as gastric ultrasound may identify high-risk patients and events that previously went unrecognized. 
  4. Fasting time is only part of the assessment: Gastric ultrasound can provide a direct assessment of gastric contents in selected patients, supporting a more individualized approach when fasting history alone does not adequately define aspiration risk.

BACKGROUND

Pulmonary aspiration is uncommon, but when it occurs, it can lead to serious respiratory complications and even death.(2,4,9,12) A recent analysis of nearly one million anesthetic encounters estimated that clinically recognized perioperative aspiration occurs in approximately 1 in 5,500 cases.(3) Although the true burden may be higher, reported cases depend on whether the event is recognized, documented, coded, and captured by the surveillance system being used.(4,9) Studies comparing different reporting methods have identified aspiration events that were missed when only one source was reviewed. As a result, subtle cases, or those that become apparent only after the procedure, may not always be classified as perioperative aspiration. 

The 2023 American Society of Anesthesiologists (ASA) Practice Guidelines for Preoperative Fasting reaffirmed the recommended fasting intervals for healthy patients undergoing elective procedures: 2 hours for clear liquids, 4 hours for breast milk, 6 hours for infant formula, non-human milk, or a light meal, and at least 8 hours following a fatty meal.(1) These recommendations continue to serve as the foundation of perioperative fasting for healthy elective patients. At the same time, the guidelines recognize that they are not intended for all patient populations. Individuals with conditions or medications that may impair gastric emptying or increase the risk of regurgitation may still have significant residual gastric contents despite following standard fasting recommendations. For these patients, perioperative assessment should extend beyond fasting duration alone and take individual risk factors into account.(1) 

The widespread use of glucagon-like-peptide-1 receptor agonists (GLP-1RAs) has brought renewed attention to the limitations of relying on fasting duration alone to estimate aspiration risk. As evidence regarding their effects on gastric emptying has evolved, perioperative recommendations have shifted from a uniform approach toward one that is more individualized. Current guidance recognizes that most patients can safely continue GLP-1RA therapy before elective procedures, while recommending additional precautions for those at higher risk of delayed gastric emptying. These precautions may include dietary modifications (24-hour liquid-diet only), adjustments to the anesthetic plan, or point-of-care gastric ultrasound when the findings are expected to influence clinical management. More recent consensus statements continue to support this patient-centered approach, emphasizing that perioperative decision-making should be based on the overall clinical picture rather than medication use alone. (5,6,7,8) 

Despite these advances in perioperative risk assessment, an important question remains. In daily clinical practice, anesthesiologists are increasingly encountering patients with factors that may delay gastric emptying despite adherence to recommended fasting guidelines. At the same time, large observational studies and national databases have not shown a corresponding increase in documented pulmonary aspiration. This raises an important question: is the incidence of perioperative pulmonary aspiration truly changing, or are improvements in risk assessment, documentation, and diagnostic tools allowing clinicians to identify events that may have previously gone unrecognized?(4,6,9)

WHY ASPIRATION MAY BE UNDERRECOGNIZED

Determining the true incidence of perioperative pulmonary aspiration remains challenging because there is no universally accepted definition of what constitutes an aspiration event. Some studies define aspiration as witnessed regurgitation with visualization of gastric contents below the vocal cords, whereas others include aspiration pneumonitis, aspiration pneumonia, or postoperative respiratory complications that develop shortly after anesthesia. (4,9,12) As a result, similar clinical events may be classified differently across studies and institutions, making direct comparisons of reported aspiration rates difficult. 

The diagnosis becomes even more challenging when aspiration is not recognized at the time it occurs. Small-volume aspiration may produce few immediate clinical signs, with respiratory symptoms becoming apparent only hours after the procedure. In these situations, postoperative hypoxemia, fever, leukocytosis, or new pulmonary infiltrates may be attributed to more common postoperative conditions such as atelectasis, pulmonary edema, or pneumonia, particularly when no aspiration event was witnessed.(9,12) Institutional differences in surveillance and reporting practices add another layer of complexity. Hospitals with established quality-improvement programs, standardized adverse-event reporting, or greater use of diagnostic tools such as gastric ultrasound may identify and document more aspiration-related events than centers that rely primarily on voluntary reporting. Therefore, differences in reported aspiration rates may reflect variations in event recognition and documentation rather than a true change in the incidence of pulmonary aspiration.(4,9,12)

WHAT CURRENT META-ANALYSES TELL US

Recent systematic reviews and meta-analyses consistently show that patients receiving GLP-1 receptor agonists are more likely to have increased residual gastric contents and experience procedure delays or cancellations because of concerns about delayed gastric emptying. Despite these findings, the available evidence has not demonstrated a statistically significant increase in documented pulmonary aspiration or aspiration pneumonia. This does not necessarily mean that aspiration risk is unchanged. Most of the available studies are retrospective and rely on inconsistent definitions of aspiration, variable postoperative follow-up, and different reporting practices across institutions, all of which may contribute to underrecognized events and outcome misclassification.(5,6,7,8,10,12) Together, the current evidence suggests that clinicians have become better at identifying patients with delayed gastric emptying, while the true incidence of perioperative pulmonary aspiration remains difficult to define.

WHY ONE INSTITUTION MAY OBSERVE MORE ASPIRATION EVENTS

An increase in aspiration events observed at a single institution should be interpreted in the context of the patient population and local clinical practice rather than viewed as definitive evidence that the overall incidence of pulmonary aspiration is increasing. Centers caring for a larger number of patients undergoing emergency procedures, or those with conditions associated with delayed gastric emptying — including obesity, diabetes, gastrointestinal disorders, or GLP-1 receptor agonist use — may naturally encounter more patients at risk of aspiration. (5,6,7,8,10,12,14,15) 

At the same time, increased awareness of aspiration risk, wider implementation of gastric ultrasound, more standardized documentation, and active quality-improvement initiatives may lead clinicians to recognize and report events that might previously have been attributed to other postoperative pulmonary complications.(4,9,14,15,16) These factors, together, may help explain why one institution reports more aspiration events even when large multicenter studies and national databases do not demonstrate a similar trend.

THE EMERGING ROLE OF GASTRIC ULTRASOUND

Recognizing that fasting duration does not always reflect gastric emptying has renewed interest in point-of-care gastric ultrasound. Rather than estimating aspiration risk based solely on the time since the last meal, gastric ultrasound allows clinicians to directly assess gastric contents immediately before anesthesia. This bedside examination can identify an empty stomach, clear fluids, or solid contents, providing information that may be particularly valuable when the patient’s aspiration risk is uncertain or when the clinical history is inconclusive.(14,15,16) 

Professional societies increasingly recognize gastric ultrasound as a useful adjunct in selected patients, not as a replacement for standard fasting guidelines. Its role is strongest when the results are expected to influence perioperative management, such as in patients with suspected delayed gastric emptying, uncertain fasting status, or other factors associated with increased aspiration risk.(1,5,8,14,16) 

Although gastric ultrasound cannot prevent pulmonary aspiration, it provides something that fasting guidelines alone cannot: a direct assessment of gastric contents, which can help clinicians decide whether to proceed with surgery, modify anesthetic technique, extend fasting, or postpone an elective procedure. As it becomes more widespread and operator experience continues to grow, gastric ultrasound has the potential to refine perioperative risk assessment and support more individualized clinical decision-making.(5,8,14,15,16)

REFERENCES

  1. 1. Joshi GP, Abdelmalak BB, Weigel WA, et al. 2023 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting: a modular update of the 2017 guidelines. Anesthesiology. 2023;138(2):132-151. doi:10.1097/ALN.0000000000004381. 
  2. Cook TM, Woodall N, Frerk C. Major complications of airway management in the UK: results of the Fourth National Audit Project. Part 1: Anaesthesia. Br J Anaesth. 2011;106(5):617-631. doi:10.1093/bja/aer058. 
  3. Anesthesiology News. Large study details incidence, outcomes of perioperative aspiration. Anesthesiology News. 2025 Feb 4. 
  4. Zdravkovic M, Berger-Estilita J, Kovacec JW, Sorbello M, Mekis D. A way forward in pulmonary aspiration incidence reduction: ultrasound, mathematics, and worldwide data collection. Braz J Anesthesiol. 2023;73(3). doi:10.1016/j.bjane.2021.05.004. 
  5. Oprea AD, Ostapenko LJ, Sweitzer B, et al. Perioperative management of patients taking glucagon-like peptide 1 receptor agonists: SPAQI multidisciplinary consensus statement. Br J Anaesth. 2025;135(1):48-78. doi:10.1016/j.bja.2025.04.001. 
  6. Elmati PR, Sai G, Qasba RK, et al. GLP-1 agonists and the risk of pulmonary aspiration during elective upper endoscopy: a systematic review and meta-analysis. Open Respir Med J. 2025;19(1). doi:10.2174/0118743064372550250603061720. 
  7. Huang H, Hu C, Liu F, Ji F, Fu Y, Cao M. Glucagon-like peptide-1 receptor agonists and impaired gastric emptying: a pharmacovigilance analysis of the US FDA adverse event reporting system. Br J Anaesth. 2024. doi:10.1016/j.bja.2024.10.013. 
  8. Baettig SJ, Filipovic MG, Bomberg H, Hofer CK, Ganter MT. Anaesthesiologic management of patients at risk of pulmonary aspiration: a Swiss consensus statement. BMC Anesthesiol. 2026;26(1). doi:10.1186/s12871-026-03835-7. 
  9. Battaglini D, De Rosa S. Aspiration after anesthesia: chemical versus bacterial, differential diagnosis, management, and prevention. Semin Respir Crit Care Med. 2024;45(6):659-668. doi:10.1055/a-2458-4450. 
  10. Pereira T, Pereira ROL, Maia E, et al. Impact of glucagon-like peptide-1 receptor agonists in patients undergoing anesthesia or sedation: systematic review and meta-analysis. Perioper Med (Lond). 2024;13(1). doi:10.1186/s13741-024-00439-y. 
  11. de Pretis N, Calderini E, Mora SM, et al. Aspiration pneumonia after ERCP under anesthesiologist-administered sedation: prevalence, risk factors and clinical outcomes of an underestimated adverse event. Medicina (Kaunas). 2025;61(12):2172. doi:10.3390/medicina61122172. 
  12. Gupte T, Knack A, Cramer JD. Mortality from aspiration pneumonia: incidence, trends, and risk factors. Dysphagia. 2022;37(6). doi:10.1007/ s00455-022-10412-w. 
  13. Sitges-Milà C, Boixeda Viu R, Almirall J. Aspiration pneumonia: epidemiology, risk factors, etiology, diagnosis, treatment, prophylaxis, and prognosis. Barcelona Respir Netw Rev. 2025;11(2). doi:10.23866/brnrev:2025-m0132. 
  14. Razak A, Baburyan S, Lee E, Costa A, Bergese SD. Role of point-of-care gastric ultrasound in advancing perioperative fasting guidelines. Diagnostics (Basel). 2024;14(21):2366. doi:10.3390/diagnostics14212366. 
  15. Pan X, Chai J, Gao X, et al. Diagnostic performance of ultrasound in the assessment of gastric contents: a meta-analysis and systematic review. Insights Imaging. 2024;15(1). doi:10.1186/s13244-024-01665-0. 
  16. Haskins SC, Kalagara H, Bronshteyn YS, Perlas A. ASRA Pain Medicine narrative review and expert practice recommendations for gastric pointof-care ultrasound to assess aspiration risk in medically complex patients undergoing regional anesthesia and pain procedures: infographic. Reg Anesth Pain Med. 2025:rapm-2025-106926. doi:10.1136/rapm-2025-106926.