Modified method of ultrasound gastric volume assessment for evaluating the risk of aspiration in different patient positions on the operating table: a prospective observational study

Introduction. The developed modified method of ultrasound gastric contents assessment in the patient’s position on the operating table with the head end raised by 30 degrees and with the operating table rotated to the right side by 30 degrees (30/30 position) allows evaluating the risk of aspiration without the need of physically turning the patient on the operating table and shows high diagnostic value comparable to the method on the right side. However, the unstable position of the patient made it difficult to implement it in clinical practice and required a reduction in the angles of the operating table.

The objective was to compare the data of ultrasound stomach volume assessment calculated using a modified formula with the patient in a 30/30 position on the operating table and with the patient in a position on the operating table with its head elevated by 15 degrees and rotated to the right side of the operating table by 15 degrees (15/15 position).

Materials and methods. The prospective observational study included 30 patients (14 men, 16 women). Ultrasound examination (U/S) of the stomach antrum was performed in the 15/15, 30/30, and right lateral decubitus. The volume of gastric contents was calculated using a modified formula for the 15/15 and 30/30 positions and the A. Perlas formula for the right lateral decubitus.

Results. After taking 200 ml of apple juice, the stomach antrum stretched and became more rounded, and hypoechoic fluid, which moved by gravity, was clearly visible. There were no statistical group differences in the volume of gastric contents between the 15/15 (162.01 (94.53; 205.20) ml), 30/30 (159.71 (113.04; 186.94) ml) and right lateral (160.59 (103.92; 192.23) ml) decubitus (p = 0.407). A detailed analysis between the groups, taking into account post-hoc comparisons, revealed no differences in the calculated gastric volume.

Conclusion. The study showed that the modified formula for measuring the gastric volume not only gives approximately the same results for predicting the risk of aspiration during induction of anesthesia for the 15/15 and 30/30 positions, but also maintains statistical comparability with the calculated volume of the stomach according to the A. Perlas formula on the right side.

1. Aleksandrovich Yu. S., Pshenisnov K. V., Shorahmedov Sh. Sh. Preoperative fasting during elective surgical interventions in children. Russian Bulletin of Pediatric Surgery, Anesthesiology and Resuscitation, 2024, vol. 14, no. 2, pp. 215–228. (In Russ.). http://doi.org/10.17816/psaic1786.

2. Lakhin R. E., Gettuev A. T., Mikhailyuk Yu. Yu. et al. Development of a modified formula for ultrasound assessment of gastric volume: a prospective observational study. Bulletin of Intensive Therapy named after A. I. Saltanov, 2025, no. 2, pp. 74–85. (In Russ.). http://doi.org/10.21320/1818-474X-2025-2-74-85.

3. Leiderman I. N., Gritsan A. I., Zabolotskikh I. B. et al. Perioperative nutritional support. Guidelines of the Federation of Anesthesiologists and Resuscitators. A. I. Saltanov Bulletin of Intensive Care, 2022, no. 4, pp. 7–20. (In Russ.). http://doi.org/10.21320/1818-474X-2021-4-7-20.

4. Arzola C., Perlas A., Siddiqui N. T. et al. Gastric ultrasound in the third trimester of pregnancy: a randomised controlled trial to develop a predictive model of volume assessment. Anaesthesia, 2018, vol. 73, pp. 295–303. http://doi.org/10.1111/anae.14131.

5. Bartusch O. M., Finkl M., Jaschinski U. Aspiration syndrome: epidemiology, pathophysiology, and therapy. Anaesthesist, 2008, vol. 57, no. 5, pp. 519–30, http://doi.org/10.1007/s00101-008-1348-4.

6. Bouvet L., Chassard D. Ultrasound assessment of gastric content in the obese patient: one more step for patient safety. Anesth Analg, 2014, vol. 119, no. 5, pp. 1017–1018. http://doi.org/10.1213/ANE.0000000000000403.

7. Bouvet L., Mazoit J. X., Chassard D. et al. Clinical assessment of the ultrasonographic measurement of antral area for estimating preoperative gastric content and volume. Anesthesiology, 2011, vol. 114, no. 5, pp. 1086–1092. http://doi.org/10.1097/ALN.0b013e31820dee48.

8. Çalışır F., Öksüz G. Comparison of gastric volumes using ultrasound in term pregnant women with and without gestational diabetes before elective cesarean delivery: an observational cohort study. J Matern Fetal Neonatal Med, 2025, vol. 38, no. 1, pp. 2508267. http://doi.org/10.1080/14767058.2025.2508267.

9. Collins G. S., Moons K. G. M., Dhiman P. et al. TRIPOD+AI statement: updated guidance for reporting clinical prediction models that use regression or machine learning methods. BMJ, 2024, vol. 385, e078378. http://doi.org/10.1136/BMJ-2023-078378.

10. Cubillos J., Tse C., Chan V. W. S. et al. Bedside ultrasound assessment of gastric content: an observational study. Can J Anaesth, 2012, vol. 59, no. 4, pp. 416–423. http://doi.org/10.1007/S12630-011-9661-9.

11. Demirel A., Özgünay Ş. E., Eminoğlu Ş. et al. Ultrasonographic evaluation of gastric content and volume in pediatric patients undergoing elective surgery: a prospective observational study. Children (Basel), 2023, vol. 10, no. 9. – P. 1432. http://doi.org/10.3390/CHILDREN10091432.

12. Desgranges F.P., Chassard D., Zieleskiewicz L. et al. Ultrasound assessment of gastric contents at the end of pregnancy. Int J Obstet Anesth, 2018, vol. 35, pp. 116–117. http://doi.org/10.1111/anae.14010.

13. Fujigaki T., Fukusaki M., Nakamura H. et al. Quantitative evaluation of gastric contents using ultrasound. J Clin Anesth, 1993, vol. 5, no. 6, pp. 451–455. http://doi.org/10.1016/0952-8180(93)90059-N.

14. Geriatric Anesthesia and Perioperative Management Group of the Chinese Society of Anesthesiology; National Alliance of Geriatric Anesthesia (NAGA); National Clinical Research Center for Geriatric Diseases (Xuanwu Hospital). [Clinical practice guidelines for perioperative fluid therapy in Chinese adult patients (2025 edition)], 2025, vol. 105, no. 2, pp. 128–154. http://doi.org/10.3760/cma.j.cn112137-20241003-02245.

15. Gola W., Domagała M., Cugowski A. Ultrasound assessment of gastric emptying and the risk of aspiration of gastric contents in the perioperative period. Anaesthesiol Intensive Ther, 2018, vol. 50, no. 4, pp. 297–302. http://doi.org/10.5603/AIT.a2018.0029.

16. Hveem K., Hausken T., Berstad A. Ultrasonographic assessment of fasting liquid content in the human stomach. Scand J Gastroenterol, 1994, vol. 29, no. 9, pp. 786–789. http://doi.org/10.3109/00365529409092511.

17. Inan S., Erdivanli B. Ultrasound evaluation of gastric emptying and comparison with patient-reported risk factors in elective surgical patients. J Clin Med, 2025, vol. 14, no. 2, pp. 641. http://doi.org/10.3390/jcm14020641.

18. Kaye A. D., Jones M. R., Viswanath O. et al. ASIPP Guidelines for sedation and fasting status of patients undergoing interventional pain management procedures. Pain Physician, 2019, vol. 22, no. 3, pp. 201–207. PMID: 31151329.

19. Kluger M. T., Culwick M. D., Moore M. R. et al. Aspiration during anaesthesia in the first 4000 incidents reported to webAIRS. Anaesthesia and Intensive Care, 2019, vol. 47, no. 5, pp. 442–451. http://doi.org/10.1177/0310057X19854456.

20. Kluger M. T., Short T. G. Aspiration during anaesthesia: a review of 133 cases from the Australian Anaesthetic incident monitoring study (AIMS). Anaesthesia, 1999, vol. 54, pp. 19–26.

21. Lienhart A., Auroy Y., Pequignot F. et al. Survey of anesthesia-related mortality in France. Anesthesiology, 2006, vol. 105, pp. 1087–1097.

22. Narayanasamy S., Weethee J. B., Rao D. S. et al. Point-of-care ultrasound for gastric volume measurement in a pediatric patient-look beyond the antrum: a case report. A A Pract, 2024, vol. 18, no. 7, e01824. http://doi.org/10.1213/XAA.0000000000001824.

23. Neelakanta G., Chikyarappa A. A review of patients with pulmonary aspiration of gastric contents during anesthesia reported to the departmental quality assurance committee. J Clin Anesth, 2006, vol. 18, pp. 102–107.

24. Ni X., Li J., Wu Q.W. et al. Ultrasound evaluation of gastric emptying of high-energy semifluid solid beverage in parturients during labor at term: a randomized controlled trial. J Anesth, 2024, vol. 38, no. 1, pp. 29–34. http://doi.org/10.1007/s00540-023-03269-2.

25. Perlas A., Arzola C. Pulmonary aspiration of gastric contents: can we improve patient outcomes? Anesthesiology, 2021, vol. 135, no. 2, pp. 209–211. https://doi.org/10.1097/ALN.0000000000003861.

26. Perlas A., Chan V. W. S., Lupu C. M. et al. Ultrasound assessment of gastric content and volume. Anesthesiology, 2009, vol. 111, no. 1, pp. 82–89. https://doi.org/10.1097/ALN.0B013E3181A97250.

27. Perlas A., Mitsakakis N., Liu L. et al. Validation of a mathematical model for ultrasound assessment of gastric volume by gastroscopic examination. Anesth Analg, 2013, vol. 116, no. 2, pp. 357–363. http://doi.org/11.1213/ANE.0b013e318274fc19.

28. Perlas A., Van De Putte P., Van Houwe P. et al. I-AIM framework for point-of-care gastric ultrasound. Br J Anaesth, 2016, vol. 116, no. 1, pp. 7–11. http://doi.org/:10.1093/BJA/AEV113.

29. Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration: Application to Healthy Patients Undergoing Elective Procedures: An Updated Report by the American Society of Anesthesiologists Task Force on Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration. Anesthesiology, 2017, vol. 126, no. 3, pp. 376–393. http://doi.org/10.1097/ALN.0000000000001452.

30. Queiroz V. N. F., Falsarella P. M., Chaves R. C. F. et al. Evaluation of gastric content in fasting patient during semaglutide use: an observational study. Surg Obes Relat Dis, 2025, vol. 21, no. 2, pp. 146–151. http://doi.org/10.1016/j.soard.2024.08.039.

31. Sander T., Urmson K., Langford L. et al. Determining residual gastric volume in healthy children using ultrasound. Can J Anaesth, 2023, vol. 70, no. 8, pp. 1323–1329. http://doi.org/10.1007/s12630-023-02526-y.

32. Sanivarapu R. R., Gibson J. Aspiration pneumonia. In: StatPearls. Treasure Island (FL): StatPearls Publishing; June 5, 2021. URL: https://www.statpearls.com/nurse/ce/activity/23265 (accessed: 10.11.25).

33. Schmitz A., Thomas S., Melanie F. et al. Ultrasonographic gastric antral area and gastric contents volume in children. Paediatr Anaesth, 2012, vol. 22, no. 2, pp. 144–149. http://doi.org/10.1111/J.1460-9592.2011.03718.X.

34. Sun J., Wei G., Hu L. et al. Perioperative pulmonary aspiration and regurgitation without aspiration in adults: a retrospective observational study of 166,491 anesthesia records. Annals of Palliative Medicine, 2021, vol. 10, no. 4, pp. 4037–4046. https://doi.org/10.21037/APM-20-2382.

35. Tacken M. C. T., van Leest T. A. J., van de Putte P. et al. Ultrasound assessment of gastric volumes of thick fluids: Validating a prediction model. Eur J Anaesthesiol, 2021, vol. 38, no. 12, pp. 1223–1229. http://doi.org/10.1097/EJA.0000000000001465.

36. Tan Y., Wang X., Yang H. et al. Ultrasonographic assessment of preoperative gastric volume in patients with dyspepsia: a prospective observational study. BMC Anesthesiol, 2022, vol. 22, no. 1, pp. 21. https://doi.org/10.1186/s12871-021-01559-4.

37. Van De Putte P., Perlas A. Ultrasound assessment of gastric content and volume. Br J Anaesth, 2014, vol. 113, no. 1, pp. 12–22. http://doi.org/:10.1093/bja/aeu151.

38. Van de Putte P., Vernieuwe L., Jerjir A. et al. When fasted is not empty: a retrospective cohort study of gastric content in fasted surgical patients. Br J Anaesth, 2017, vol. 118, no. 3, pp. 363–371. http://doi.org/10.1093/bja/aew435.

39. Warner M., Meyerhoff K., Warner M. et al. Pulmonary aspiration of gastric contents: a closed claims analysis. Anesthesiology, 2021, vol. 135, no. 2, pp. 284–291. https://doi.org/10.1097/ALN.0000000000003831.

40. Weimann A., Braga M., Carli F. et al. ESPEN practical guideline: Clinical nutrition in surgery. Clin Nutr, 2021, vol. 40, no. 7, pp. 4745–4761. http://doi.org/10.1016/j.clnu.2021.03.031.

41. Wolla C. D., Pecha T. J., Sirianni J. M. et al. Ultrasound assessment of preoperative gastric volume in fasted diabetic surgical patients: A prospective observational cohort study on the effects of glucagon-like peptide-1 agonists on gastric emptying. J Clin Anesth, 2025, vol. 104, 111853. http://doi.org/10.1016/j.jclinane.2025.111853.