High-flow oxygen compared with standard oxygen to prevent low oxygen levels during sedated gastrointestinal endoscopy
| ISRCTN | ISRCTN69124611 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN69124611 |
| Sponsor | National Institute of Emergency Medicine "Pirogov" |
| Funder | Investigator initiated and funded |
- Submission date
- 23/03/2026
- Registration date
- 25/03/2026
- Last edited
- 25/03/2026
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Surgery
Plain English summary of protocol
Background and study aims
During gastrointestinal endoscopy performed under sedation, patients may develop low oxygen levels due to the effects of sedative drugs on breathing. Standard oxygen therapy delivered through a nasal cannula may not always be sufficient to prevent this. High-flow oxygen therapy delivers warmed and humidified oxygen at higher flow rates and may improve oxygen levels. The aim of this study is to compare high-flow oxygen with standard oxygen therapy in preventing low oxygen levels during sedated endoscopy.
Who can participate?
Adults aged 18 years or older undergoing planned gastrointestinal endoscopy under sedation in a hospital setting.
What does the study involve?
Participants receive oxygen therapy during their endoscopic procedure as part of routine care. Depending on the attending anesthesiologist’s decision, patients receive either standard oxygen through a nasal cannula or high-flow oxygen therapy. Vital signs, including oxygen levels, heart rate, and blood pressure, are monitored continuously during the procedure. The study records any episodes of low oxygen levels and any interventions required to support breathing.
What are the possible benefits and risks of participating?
Participants may benefit from improved monitoring and oxygen support during the procedure. There are no additional risks beyond standard clinical care, as both oxygen delivery methods are routinely used in clinical practice.
Where is the study run from?
The study is conducted at University Hospital “N. I. Pirogov”, Sofia, Bulgaria.
When is the study starting and how long is it expected to run for?
The study starts in March 2025 and runs until August 2025.
Who is funding the study?
Investigator initiated and funded.
Who is the main contact?
Mina Vapireva, MD
mvapireva@gmail.com
Contact information
Public, Scientific, Principal investigator
21 Totleben Blvd.
Sofia
1606
Bulgaria
 ORCID ID |
0009-0003-1064-212X |
|---|---|
| Phone | +359 888722749 |
| mvapireva@gmail.com |
Study information
| Primary study design | Observational |
|---|---|
| Observational study design | Cohort study |
| Scientific title | Adult patients undergoing sedated gastrointestinal endoscopy receiving high-flow nasal oxygen compared with low-flow nasal oxygen for the prevention of hypoxemia: a prospective observational study |
| Study acronym | HFNO-ENDO |
| Study objectives | The aim of this study is to evaluate whether high-flow nasal oxygen is associated with a reduced incidence of hypoxemia compared with low-flow nasal oxygen in adult patients undergoing sedated gastrointestinal endoscopy. The study also aims to assess the impact of the oxygenation strategy on airway interventions and procedural safety in routine clinical practice. |
| Ethics approval(s) |
Approved 20/03/2025, Ethics Committee of the National Institute of Emergency Medicine "Pirogov" (21 Totleben Blvd., Sofia, 1606, Bulgaria; +359 29154411; pirogov@pirogov.bg), ref: EK-04-25/20.03.2025 |
| Health condition(s) or problem(s) studied | Hypoxemia during gastrointestinal endoscopy under procedural sedation in adult patients |
| Intervention | This is a single-center prospective observational cohort study conducted in adult patients undergoing elective gastrointestinal endoscopy under procedural sedation. Patients receive either low-flow nasal oxygen or high-flow nasal oxygen. Baseline demographic and clinical data are recorded. Continuous monitoring includes pulse oximetry, heart rate, and non-invasive blood pressure. The occurrence of oxygen desaturation and other adverse events is recorded throughout the procedure. Oxygen desaturation is defined as peripheral oxygen saturation below 90 percent. Airway interventions and escalation of oxygen therapy are documented. Statistical analysis is performed to compare outcomes between the two groups and to identify factors associated with desaturation. |
| Intervention type | Device |
| Phase | Not Applicable |
| Drug / device / biological / vaccine name(s) | High-flow nasal oxygen delivery system (heated and humidified oxygen therapy) and standard low-flow nasal cannula oxygen therapy |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 29/08/2025 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Mixed |
| Lower age limit | 18 Years |
| Upper age limit | 100 Years |
| Sex | All |
| Target sample size at registration | 140 |
| Total final enrolment | 140 |
| Key inclusion criteria | 1. Adults aged 18 years or older 2. Undergoing elective gastrointestinal endoscopy (upper, lower, or combined) 3. Receiving procedural sedation 4. Inpatients |
| Key exclusion criteria | 1. Emergency procedures 2. Endoscopic retrograde cholangiopancreatography 3. Hemodynamic instability 4. Contraindications to sedation 5. Pregnancy 6. Refusal to participate |
| Date of first enrolment | 21/03/2025 |
| Date of final enrolment | 29/08/2025 |
Locations
Countries of recruitment
- Bulgaria
Study participating centres
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|---|
| IPD sharing plan |
Editorial Notes
25/03/2026: Trial's existence confirmed by Ethics Committee of the National Institute of Emergency Medicine "Pirogov".
