Does Pre-operative Gastric Ultrasound Influence Anaesthetic Decision-Making in Chronic Pain Patients? A Prospective Observational Cohort.

Official title

Does Pre-operative Gastric Ultrasound Influence Anaesthetic Decision-Making in Chronic Pain Patients? A Prospective Observational Cohort Study

Overview

Gastric POCUS has been validated and shown to be an accurate diagnostic tool in both healthy individuals and medically complex patient populations. Regional anaesthesiologists and pain management physicians frequently provide sedation or anaesthetic care for medically complex patients who fall outside the limited applicability of existing fasting guidelines, including patients with chronic pain, poor acute-on-chronic pain control, and those receiving acute or chronic opioid therapy. These patients are at risk of delayed gastric emptying and may therefore benefit from additional pre-procedural assessment using gastric ultrasound prior to elective interventions

Detailed description

This study is the first prospective evaluation of gastric ultrasound in this high-risk, understudied population, incorporating quantitative opioid exposure and focusing on its impact on real-time anaesthetic decision-making. By linking gastric ultrasound findings to changes in peri-procedural management, this work extends gastric POCUS from a diagnostic tool to a clinically actionable risk-stratification strategy.

The aim of this study is to determine whether pre-operative gastric POCUS provides decision-relevant information that influences peri-operative aspiration risk assessment and leads to modification of pre-defined anaesthetic management plans in chronic pain patients undergoing elective interventional procedures under sedation.

Pre-procedural gastric ultrasound will be performed immediately before initiation of sedation by the investigators experienced in gastric point-of-care ultrasound, each having completed at least 30 supervised examinations. A standardised scanning protocol was used. Qualitative assessment of gastric contents was performed in the supine position and in the right lateral decubitus position. When patient-related factors precluded these positions, scanning was performed in a semi-recumbent position at approximately 45°.

Gastric contents will be classified qualitatively as:

* Empty * Fluid (homogeneous hypoechoic contents) * Solid or mixed (heterogeneous contents with echogenic material) When fluid content was identified, the gastric antral cross-sectional area (CSA) was measured at rest in a parasagittal plane at the level of the abdominal aorta using the serosal tracing method, as previously described. Gastric fluid volume was estimated using the validated Perlas mathematical model.

In accordance with current literature and consensus recommendations, patients with solid or mixed gastric contents were classified as having a high aspiration risk. For patients with fluid contents, a gastric volume threshold of \>1.5 ml·kg-¹ body weight was used to define high aspiration risk. Patients with an empty stomach or fluid volumes ≤1.5 ml·kg-¹ were classified as low risk.

Following completion of gastric ultrasound and prior to initiation of sedation, the responsible anaesthetist reassessed the patient's aspiration risk incorporating the ultrasound findings. The anaesthetist documented whether the original anaesthetic management plan was:

* Unchanged * Modified to a more conservative approach (additional measures to reduce aspiration risk) * Modified to a more liberal approach Anaesthetic management modifications were made at the discretion of the responsible anaesthesiologist to ensure patient safety. The anesthesiologist responsible for patient care will not be blinded to ultrasound findings, consistent with the observational nature of the study.

Primary outcome measures

• The proportion of patients in whom pre-procedural gastric ultrasound resulted in a change to the pre-defined anesthetic management plan. [Time frame: 1- 2 hours]

Secondary outcome measures (3)

• Prevalence of high-risk gastric contents despite adherence to fasting guidelines [Time frame: 1- 2 hours]
• Associations between gastric ultrasound findings and patient-related factors, including opioid use and comorbidities [Time frame: 1-2 hours]
• Qualitative and quantitative gastric ultrasound findings [Time frame: 1-2 hours]

Eligibility criteria

Inclusion Criteria: Patients were eligible for inclusion if they met all of the following criteria:

• Age ≥18 years
• Scheduled for elective chronic pain interventional procedures under procedural sedation
• Adherence to standard preoperative fasting guidelines (≥6 hours for clear fluids and ≥8 hours for solids)
• Presence of at least one clinical factor associated with delayed gastric emptying or increased risk of pulmonary aspiration, including:
• Chronic opioid use (≥2 weeks)
• Acute opioid administration within 24 hours prior to the procedure
• Poorly controlled acute-on-chronic pain
• Diabetes mellitus without established autonomic neuropathy
• Symptoms of gastroesophageal reflux
• Reduced functional mobility
• ASA physical status II-III

Exclusion Criteria: Patients will be excluded if any of the following present:

• Age <18 years
• Previous gastric or esophageal surgery
• Known pregnancy
• Known hiatal hernia
• Severe neurological disorders affecting swallowing or gastric motility
• Established autonomic neuropathy affecting gastric emptying (e.g. advanced diabetic gastroparesis)
• Morbid obesity (body mass index ≥35 kg·m-²), due to known limitations in gastric ultrasound image acquisition and reduced validity of volume estimation models
• Inability to provide informed consent

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Cohort

Study locations

United Arab Emirates · 1 center

• Danat Al Emarat Women & Children Hospital — Abu Dhabi

Publications

• Gola W, Domagala M, Cugowski A. Ultrasound assessment of gastric emptying and the risk of aspiration of gastric contents in the perioperative period. Anaesthesiol Intensive Ther. 2018;50(4):297-302. doi: 10.5603/AIT.a2018.0029. Epub 2018 Sep 17. PMID 30221339
• Charlesworth M, Wiles MD. Pre-operative gastric ultrasound - should we look inside Schrodinger's gut? Anaesthesia. 2019 Jan;74(1):109-112. doi: 10.1111/anae.14516. No abstract available. PMID 30511749
• Pan X, Chai J, Gao X, Li S, Liu J, Li L, Li Y, Li Z. Diagnostic performance of ultrasound in the assessment of gastric contents: a meta-analysis and systematic review. Insights Imaging. 2024 Mar 27;15(1):98. doi: 10.1186/s13244-024-01665-0. PMID 38536581
• Haskins SC, Kruisselbrink R, Boublik J, Wu CL, Perlas A. Gastric Ultrasound for the Regional Anesthesiologist and Pain Specialist. Reg Anesth Pain Med. 2018 Oct;43(7):689-698. doi: 10.1097/AAP.0000000000000846. PMID 30052550
• Perlas A, Van de Putte P, Van Houwe P, Chan VW. I-AIM framework for point-of-care gastric ultrasound. Br J Anaesth. 2016 Jan;116(1):7-11. doi: 10.1093/bja/aev113. Epub 2015 May 7. No abstract available. PMID 25951832
• Kruisselbrink R, Gharapetian A, Chaparro LE, Ami N, Richler D, Chan VWS, Perlas A. Diagnostic Accuracy of Point-of-Care Gastric Ultrasound. Anesth Analg. 2019 Jan;128(1):89-95. doi: 10.1213/ANE.0000000000003372. PMID 29624530
• Perlas A, Chan VW, Lupu CM, Mitsakakis N, Hanbidge A. Ultrasound assessment of gastric content and volume. Anesthesiology. 2009 Jul;111(1):82-9. doi: 10.1097/ALN.0b013e3181a97250. PMID 19512861
• Bouvet L, Mazoit JX, Chassard D, Allaouchiche B, Boselli E, Benhamou D. Clinical assessment of the ultrasonographic measurement of antral area for estimating preoperative gastric content and volume. Anesthesiology. 2011 May;114(5):1086-92. doi: 10.1097/ALN.0b013e31820dee48. PMID 21364462

Identifiers

NCT: NCT07537582 · RPDAE/2026/102

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗