Archive page

Croat Nurs J. 2026; 10(1): 121-134 Review

Efficacy of High-Flow Nasal Cannula in Preventing Hypoxemia During Sedated Endoscopic Procedures:

A Literature Review

1,2Valentina Ješić

3 Jadranka Pavić

1 Marinko Vučić

1 Tihana Magdić Turković

3 Martina Smrekar

1 Sestre milosrdnice University Hospital Center, Zagreb, Croatia, Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, Zagreb, Croatia

2 Faculty of Health Sciences, University of Novo Mesto, Novo Mesto, Slovenia

3 University of Applied Health Sciences, Zagreb, Croatia

Article received: 26. 08. 2025.

Article accepted: 20. 10. 2025.

DOI: 10.24141/2/10/1/12

Author for correspondence:

Valentina Ješić

Sestre milosrdnice University Hospital Center, Zagreb, Croatia

E-mail: valentina.matic@yahoo.com

Keywords: high-flow nasal cannula, hypoxemia, endosco- pic procedures, sedation

Abstract

Introduction. Hypoxemia is a common and poten- tially serious complication during endoscopic proce-

dures performed under sedation, particularly in pa- tients with obesity, chronic respiratory disease, or reduced pulmonary reserve. The high flow nasal can- nula (HFNC) delivers heated and humidified oxygen at high flow rates with a stable fraction of inspired oxygen (FiO2), thereby reducing desaturation and improving oxygenation compared with conventional oxygen delivery methods.

Aim. This review evaluated the efficacy of HFNC in preventing hypoxemia during gastrointestinal endos- copy, bronchoscopy, and endoscopic retrograde chol- angiopancreatography (ERCP) under sedation, focus- ing on clinical applicability and patient safety.

Methods. A systematic search of PubMed, Web of Science, and Scopus (2015–2025) identified English language studies, including randomized trials, com- parative and observational studies, and reviews. Pre- defined inclusion criteria were applied, and outcomes included the incidence of hypoxemia, minimum SpO2, and the need for airway interventions.

Results. Of 628 records screened, 30 studies met the inclusion criteria (13 randomized trials, 3 prospective comparative, 1 observational, 3 retrospective, and 10 systematic reviews or meta-analyses). Most confirmed that HFNC reduces hypoxemia, increases minimum SpO2, and improves ventilation stability compared with conventional oxygen therapy. The greatest ben- efits were observed among high-risk patients such as elderly, obese, and those with respiratory disease. Op- timal flow rates ranged from 50 to 60 L/min, ensuring efficacy, comfort, and safety.

Conclusion. HFNC provides effective oxygenation support during sedated endoscopic procedures, reducing desaturation and the need for airway in- terventions. Standardized protocols and further re- search on long term outcomes are recommended.

Introduction

Hypoxemia is one of the most common and serious complications during sedated endoscopic procedures, particularly in patients at increased risk due to res- piratory diseases, obesity, or other factors that re- duce pulmonary reserve (1). Conventional methods of oxygenation support, such as conventional oxy- gen therapy (COT) delivered via nasal cannula or face mask, are often insufficient to maintain adequate ox- ygenation in conditions of increased oxygen demand and reduced respiratory volume caused by sedation

(2). Therefore, advanced non-invasive oxygenation methods are increasingly being applied in clinical practice, among which the high-flow nasal cannula (HFNC) is gaining an increasingly important role.

Despite the increasing use of HFNC, its application in procedural sedation and endoscopy has not yet been standardized, and the determination of optimal flow rates and indications varies across clinical cent- ers in different countries. In addition, considerable heterogeneity exists regarding study design, seda- tion protocols, and definitions of hypoxemia, which complicates the development of unified guidelines. Given the growing number of endoscopic procedures performed under sedation and the increasingly com- plex patient population, there is a need for a detailed analysis of the effectiveness of HFNC in this context. Numerous studies have shown that the incidence of hypoxemia during gastrointestinal endoscopy under sedation may range from as low as 1.8% to as high as 69% (9–12).

HFNC delivers heated and humidified oxygen at high           flow rates (typically 30–60 L/min) with precise con-

trol of the fraction of inspired oxygen (FiO2) (3). This technology provides partial positive pressure sup- port (PEEP effect), reduces dead space in the upper airways, improves alveolar ventilation, and enhances overall gas exchange (4). HFNC increases the partial pressure of arterial oxygen (PaO2), reduces respira- tory effort, and improves patient comfort compared with traditional methods (5). In addition, continuous airflow through the upper airways prevents rebreath- ing of carbon dioxide (CO2), thereby reducing the risk of hypercapnia, which is a common problem in sedat- ed patients during procedures such as bronchoscopy, gastroscopy, or endoscopic retrograde cholangiopan- creatography (ERCP).

The significance of HFNC is particularly evident in patients at high risk of developing hypoxemia, includ- ing elderly individuals, patients with elevated BMI, those with chronic lung diseases (e.g., COPD, intersti- tial lung disease), and patients undergoing prolonged or invasive endoscopic procedures (6,7). Numerous studies and meta-analyses report that HFNC reduces the incidence of hypoxemic episodes, the need for procedural interruptions, and additional airway in- terventions (e.g., mask ventilation, intubation), while simultaneously increasing minimum oxygen satura- tion (SpO2). Compared with COT or low-flow oxygen therapy, HFNC provides more stable oxygenation and better control of ventilation parameters, thereby con- tributing to the safer performance of procedures (8).

Aim

The purpose of this paper is to systematically ana- lyze the existing scientific literature on the effective- ness of high-flow nasal cannula (HFNC) in managing hypoxemia during endoscopic procedures. The study aims to identify the advantages of HFNC in compari- son with conventional methods of oxygenation sup- port. A particular emphasis was placed on outcomes such as improved oxygenation, reduced need for in- vasive ventilation, and patient safety.

Methods

A systematic literature search was conducted in July 2025 using the PubMed, Web of Science, and Sco- pus databases. Scientific articles published between 2015 and 2025 were reviewed. In accordance with PRISMA guidelines for systematic reviews, only arti- cles classified as Clinical Trial, Controlled Clinical Trial, Multicenter Study, Observational Study, Randomized Controlled Trial, Review, and Systematic Review were included.

Inclusion criteria comprised studies focusing on the use of high-flow nasal cannula (HFNC) in adult pa- tients with hypoxemia, including gastrointestinal endoscopy (gastroscopy, colonoscopy, EGD), bron- choscopy, and endoscopic retrograde cholangiopan- creatography (ERCP) performed under sedation. Pre- defined search keywords were used: “high flow nasal cannula,” HFNC, and hypoxemia. These terms were required to appear in the title, abstract, or keywords of the included articles to ensure their relevance.

Only studies published between 2015 and 2025 were included. This period was selected to capture the most recent decade of scientific evidence, re- flecting advances in high-flow nasal cannula technol- ogy, evolving procedural sedation protocols, and the growing number of clinical trials in this field. Studies published before 2015 were excluded to avoid out- dated technologies and practices that no longer rep- resent current standards.

The authors predefined the search objectives, es- tablished inclusion and exclusion criteria (see Table 1), and focused the analysis on studies investigating the use of HFNC compared with COT in adult patients. The search was further limited to articles available in English and required to contain either an abstract or full text. After duplicate removal using the Zotero ap- plication, a total of 628 records were identified for re- view (Figure 1). Two independent authors screened the titles and abstracts (n = 628), excluding 384 studies that did not meet the basic inclusion criteria or were deemed irrelevant. Full-text articles were re- trieved for 244 studies and assessed for eligibility. In the final selection round, 214 articles were excluded because they were not related to endoscopic proce- dures, resulting in 30 studies being included in the analysis, all directly addressing HFNC use in relation to endoscopic procedures.

Data extraction was conducted independently by two authors (VJ and JP), with accuracy verified through mutual comparison and consensus among all authors. The quality of the included studies was evaluated according to predefined criteria encom- passing study design, sample size, outcome report- ing, and overall methodological rigor.

Results

This systematic review includes 30 studies pub- lished between 2015 and 2025. The included stud- ies evaluated the effectiveness of high-flow nasal cannula (HFNC) in preventing hypoxemia during sedated endoscopic procedures, including gastroin- testinal endoscopy, bronchoscopy, and endoscopic retrograde cholangiopancreatography (ERCP). The PRISMA diagram (Figure 1) illustrates the selection

Identification of studies via databases and registers

Records identified from*: Databases (n = 3) PubMed (n = 37)

Web of Science (n = 174) Scopus (n = 570)

Records removed before screening:

Duplicate records removed (n

= 153)

Records screened (n = 628)

Records excluded** (n = 384 )

Reports sought for retrieval

(n = 244)

Reports not retrieved (n = 0)

Reports assessed for eligibility

(n = 30)

Reports excluded:

Reason 1

(n = 214)

Studies included in review

(n = 30)

Reports of included studies

(n = 0)

Included

Screening

Identification

Figure 1. PRISMA flow chart

process, and Table 2 provides a detailed overview of the included studies, including authors, study design, population characteristics, and key findings. To avoid redundancy, detailed numerical results are summa- rized in Table 2.

Most of the studies were conducted in China (n = 13), with additional studies originating from Japan (n

= 2), South Korea (n = 2), Australia (n = 2), Taiwan (n = 2), and Greece (n = 2), as well as single studies from Thailand, Egypt, Ecuador, France, India, and the United States. By study type, the included papers comprised 13 randomized controlled trials (RCTs), 3 prospective randomized comparative studies, 1 pro- spective observational study, 3 retrospective stud- ies, and 10 systematic reviews and meta-analyses.

As shown in Table 2, most studies confirmed that HFNC significantly reduces the incidence of hy- poxemia compared with COT and maintains higher minimum SpO2 values. Systematic reviews and meta- analyses particularly highlighted the reduced risk of hypoxemia, fewer procedural interruptions, and a decreased need for airway interventions (13, 20, 23,

25, 31, 32, 35, 37–39).

Randomized controlled trials (n = 13) demonstrated the superiority of HFNC across different populations and procedures, including bronchoscopy, ERCP, gas- troscopy, and endoscopic submucosal dissection (17, 19, 21, 24, 26, 28–30, 33, 36, 40–42). Several studies

(14, 22, 34) observed that HFNC and other methods, such as NIV or low-flow oxygen, showed comparable efficacy; however, HFNC more consistently provided greater stability of oxygenation in high-risk patients.

Retrospective and prospective studies further con- firmed that HFNC significantly reduces the occur- rence of desaturation and maintains stable SpO2 dur- ing procedures (14–16, 18, 21, 22, 27, 34).

A concise summary of these findings is presented in Table 2, which consolidates the numerical outcomes and key methodological details of all included studies.

In conclusion, the findings indicate that HFNC is most effective in preventing hypoxemia during sedated endoscopic procedures, with optimal flow rates of 50–60 L/min, and is associated with a lower risk of complications and reduced need for procedural inter- ruptions (13, 19, 42).

Discussion

This systematic review analyzed evidence from randomized trials, observational studies, and meta- analyses, all of which consistently show that HFNC significantly reduces hypoxemia and improves oxy- genation compared with COT. The following discus- sion summarizes key findings by procedure type and patient population.

HFNC during gastrointestinal endoscopy

Sedation during upper gastrointestinal endoscopic procedures often causes hypoventilation and air- way obstruction, increasing the risk of hypoxemia. Numerous studies confirm that the use of HFNC sig- nificantly reduces this risk compared with standard low-flow oxygen therapy. Meta-analyses consistent- ly report a 60–75% relative risk reduction with HFNC use (20,39).

For instance, Thiruvenkatarajan et al. (2023) demon- strated a lower incidence of hypoxemia and higher minimum oxygen saturation with HFNC (20), while Zhang et al. (2022) additionally reported a reduced need for airway interventions in patients undergoing sedated gastrointestinal endoscopy (37). In practice, HFNC markedly decreases desaturation episodes and maintains higher oxygen saturation levels than COT

(37). In practice, HFNC markedly decreases desatura- tion episodes and maintains higher oxygen satura- tion levels than COT.

These findings have been further supported by rand- omized trials. The multicenter ODEPHI RCT by Nay et al. (2021) showed that HFNC substantially reduced critical desaturation events in high-risk patients com- pared with standard oxygen therapy (30). Beyond reducing hypoxemia incidence, HFNC also decreases the need for procedural interruptions and airway maneuvers (20,30). Other studies confirmed that HFNC lowers the need for airway maneuvers and procedural interruptions, with the most pronounced benefit observed in preventing severe desaturation (9,11,22,30,37,40). The meta-analysis by Khanna et al. (2023) involving more than 3,000 patients also demonstrated significant reductions in desaturation incidents and procedure interruptions, together with higher minimum oxygen saturation (39). Although

Wang R, Li H-C, Li X-Y, Tang X, Chu H-W,

Yuan X, Tong Z-H, Sun B, 2021 (40)

Prospective randomized controlled trial

To compare modified HFNC and COT during bronchoscopy in reducing SpO2 < 90%

China

HFNC significantly reduced hypoxemia (12.5% vs 28.8%, p < 0.001) and maintained higher SpO2 during and after bronchoscopy.

Zhang W, Yuan X, Shen Y, Wang J, Xie K, Chen X, 2024 (42)

Prospective randomized controlled trial

To determine the optimal HFNC flow rate for preventing desaturation during bronchoscopy

China

The optimal HFNC flow rate for preventing desaturation in 95% of patients was 43.2 L/min

Feng Y, Chen Z, Wang J, 2024 (41)

Randomized controlled trial

To investigate the effect of transnasal HFNC therapy on gag reflex and oxygenation in elderly patients during fiberoptic bronchoscopy

China

HFNC improved SpO‐, reduced hypoxemia and gag reflex, with no significant impact on hemodynamics.

(95% CI: 36.4–56.0); 50–60 L/

min is recommended.

Lee et al. (2016) did not find a significant difference in overall hypoxemia rates, their results indicated that HFNC reduces the risk of severe hypoxemia compared with COT (8).

Collectively, the evidence shows that HFNC enhanc- es respiratory safety during sedated gastrointesti- nal endoscopy, leading to fewer and less severe de- saturation events and reducing the need for airway interventions.

HFNC during bronchoscopy

Similar benefits of HFNC have been reported during sedated bronchoscopy. Patients, especially those with impaired lung function, are highly susceptible to hypoxemia due to sedation and airway obstruction. Several studies indicate that HFNC is more effective than COT in maintaining oxygenation in this setting. The systematic review and meta-analysis by Su et al. (2021), including five RCTs, showed that HFNC sig- nificantly reduced hypoxemic events and increased

minimum SpO2 compared with COT (25). In practice, this means patients receiving HFNC were less likely to reach critically low saturation levels during the procedure.

HFNC has also been compared with other oxygena- tion techniques. The RCT by Saksitthichok et al. (2019) found comparable protection against desatu- ration between HFNC and NIV in high-risk hypoxemic patients, with no significant difference in lowest SpO2

(14). Only in the most severely hypoxemic subgroup (baseline PaO2 < 60 mmHg) did NIV provide slightly more stable oxygenation, suggesting a marginal ad- vantage of mechanical support in that population.

Observational studies (15,16) further confirmed that HFNC maintains stable SpO2 levels, often above 95%, without significant hypoxemia or procedural interruptions. Overall, HFNC improves oxygenation reserve, allowing safer and more continuous bron- choscopy with fewer complications related to oxygen deficiency.

High-risk patient populations and specific procedural conditions

The advantages of HFNC are particularly evident in vulnerable patient populations and specific proce- dural conditions. In a recent multicenter RCT (2025) in obese patients (BMI ≥ 28) undergoing sedated endoscopy, HFNC markedly reduced the incidence of hypoxemia, from 21% with COT to only 2%. Sub- clinical respiratory depression (SpO2 90–94%) also decreased from 36% to 5%, while severe hypoxemia was virtually eliminated (0% vs 4%) (19). These re- sults highlight the importance of HFNC in obese pa- tients, who desaturate more rapidly due to obstruc- tive physiology.

Similarly, in elderly patients and those with comor- bidities, HFNC has shown clear superiority over COT. Yin et al. (2024) found that among geriatric patients (>65 years) undergoing sedated gastroscopy, hy- poxemia occurred in only 3% with HFNC versus 23% with standard therapy, with higher minimum SpO2 values (28). This suggests that older patients, often more sensitive to sedatives, derive substantial ben- efit from HFNC.

The method has proven effective even under extreme environmental conditions. At high altitude (3600 m), HFNC significantly reduced hypoxemia incidence during endoscopic procedures (9% vs 37% with COT), completely preventing severe desaturation (26). This demonstrates its potential beyond conventional hos- pital settings, including environments with baseline hypoxemia caused by hypobaric conditions.

In transplant populations with reduced respiratory re- serve, HFNC has also shown benefit. In a randomized trial in post–lung transplant patients, Ben-Menachem et al. (2020) reported that HFNC nearly halved desat- uration events (43% vs 90%) and reduced procedural interruptions compared with COT (29). Collectively, evidence confirms that high-risk populations, includ- ing obese, elderly, hypoxemic, and post-transplant patients, experience the greatest clinical advantage from HFNC.

Comparison of HFNC with other methods of oxygenation support

HFNC has become a valuable tool for preventing hy- poxemia during invasive procedures under sedation, yet its limitations and comparison with alternative strategies remain relevant. Compared with non-inva- sive ventilation (NIV), HFNC provides similar oxygen-

ation support in most patients (14). Its main advan- tages are simplicity, comfort, and patient preference for nasal cannula over pressurized masks (43). How- ever, in severely compromised patients, NIV can of- fer stronger positive pressure and ventilatory assis- tance, outperforming HFNC in preventing profound hypoxemia or hypercapnia (44).

Not all studies have reported uniform benefits. In the trial by Sawase et al. (2023) during ERCP under mod- erate sedation, HFNC was applied with room air only (FiO2 21%, 40–60 L/min) and compared with low-flow O2. Under these conditions, HFNC did not signifi- cantly reduce hypoxemia or hypercapnia compared with COT (8% vs 5%; p = 0.674) (34). These results suggest that the effectiveness of HFNC depends on the delivered FiO2 and that benefits are more pro- nounced when oxygen-enriched flow (40–100% O2) is used, as is typical in clinical practice.

Regarding safety, most studies have not identified an increased rate of adverse events such as arrhyth- mias, aspiration, or post-procedural complications (19,29,39,45). Moreover, Lee et al. (2016) reported that HFNC significantly reduced the need to esca- late to more invasive support methods, including mask ventilation or NIV, in three of four analyzed tri- als (46). HFNC is generally safe and well tolerated, with minimal risk of mucosal dryness due to heated and humidified gas. Proper device setup, flow adjust- ment, and cannula fixation are essential for optimal performance.

Cumulative evidence supports HFNC as an effec- tive standard for sedated endoscopic procedures in patients at increased respiratory risk (20). Its capac- ity to reduce hypoxemia and emergent airway inter- ventions represents a major advance in procedural safety (30). Consequently, many centers have incor- porated HFNC into routine practice, especially for el- derly, obese, and pulmonary patients. Future studies should refine application protocols, including optimal flow rates, FiO2 levels, and duration. Based on cur- rent data, HFNC makes a substantial contribution to respiratory safety and deserves wider clinical imple- mentation (20).

Limitations

This systematic review has several methodological limitations. First, the literature search was restricted to three databases (PubMed, Web of Science, and Scopus) and to articles available in English which may

have introduced language and publication bias. Sec- ond, most of the included studies were conducted in Asian countries, particularly in China, which may af- fect the generalizability of the findings due to poten- tial differences in sedation protocols, clinical practice, and population characteristics. Third, heterogeneity across studies, including variable definitions of hy- poxemia, different saturation thresholds and incon- sistent flow and FiO2 settings, makes direct compari- son of results and meta-analytic conclusions more challenging. Finally, several of the included studies analyzed relatively small patient populations which may limit the statistical power and precision of the estimated effects of HFNC.

Conclusion

The analyzed studies clearly confirm that HFNC is a more effective method than COT for the prevention of hypoxemia during sedated endoscopic procedures. In addition to reducing the risk of desaturation, HFNC provides better oxygenation and decreases the need for additional airway interventions. Optimal flow rates of 50–60 L/min have proven to be the most ef- fective and well tolerated.

From a nursing perspective, understanding the prin- ciples, indications, and clinical application of HFNC can significantly improve peri-procedural patient management, particularly in high-risk populations. Integrating HFNC protocols into routine nursing prac- tice enhances respiratory safety, supports timely recognition of hypoxemia, and reduces the need for emergency interventions.

Future research should aim to define standardized protocols for HFNC use, compare different flow and FiO2 settings, and evaluate long-term outcomes and cost effectiveness across diverse clinical environ- ments. Further interdisciplinary studies are encour- aged to assess nursing-led education, monitoring strategies, and the role of nurses in optimizing HFNC implementation and patient outcomes.

Author Contributions

Conceptualization (VJ, JP, MV, TMT, MS); Data Curation (VJ), Formal Analysis (VJ, JP, MS); Writing – Original Draft (VJ), Writing – Review & Editing (VJ, JP, MV, TMT, MS). All authors reviewed and approved the final ver- sion of the manuscript.

Conflict of Interest

The authors declare no conflicts of interest.

Acknowledgments

Not applicable.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial or not for- profit sectors.

References

1. Geng W, Jia D, Wang Y, Jin S, Ren Y, Liang D, et al. A pre- diction model for hypoxemia during routine sedation for gastrointestinal endoscopy. Clinics. 2018;73:e513. https://doi.org/10.6061/clinics/2018/e513

2. Mohamed AM, Selima WZ. HFNC Oxygen Therapy vs COT in Prolonged Upper Gastrointestinal Endoscopy Inside the ICU: A Prospective, Randomized, Controlled Clinical Study. Indian J Crit Care Med. 2025;29(3):223–

   9. https://doi.org/10.5005/jp-journals-10071-24919

3. Petkar S, Wanjari D, Priya V. A Comprehensive Review on High-Flow Nasal Cannula Oxygen Therapy in Cri- tical Care: Evidence-Based Insights and Future Direc- tions [Internet]. Cureus. 2024. Available at: https:// www.cureus.com/articles/282755-a-comprehensive- review-on-high-flow-nasal-cannula-oxygen-therapy- in-critical-care-evidence-based-insights-and-future- directions Accessed: 27.07.2025.

4. Mukherjee D, Mukherjee R. High-Flow Nasal Cannula Oxygen Therapy in the Management of Respiratory Fa- ilure: A Review [Internet]. Cureus. 2023. Available at: https://www.cureus.com/articles/204106-high-flow- nasal-cannula-oxygen-therapy-in-the-management- of-respiratory-failure-a-review Accessed: 27.07.2025

5. Kim ES, Lee H, Kim SJ, Park J, Lee YJ, Park JS, et al. Effec- tiveness of high-flow nasal cannula oxygen therapy for acute respiratory failure with hypercapnia. J Tho- rac Dis. 2018;10(2):882–8. https://doi.org/10.21037/ jtd.2018.01.125

6. Chang Y, Baek MS, Kim SW, Lee SH, Kim JS, Park SY, et al. Home High-Flow Nasal Cannula in Patients with Chronic Respiratory Failure: A Literature Review and Suggestions for Clinical Practice. Tuberc Respir Dis. 2025;88(2):264–77. https://doi.org/10.4046/ trd.2024.0196

7. Long B, Liang SY, Lentz S. High flow nasal cannula for adult acute hypoxemic respiratory failure in the ED setting. Am J Emerg Med. 2021 Nov;49:352–9. https:// doi.org/10.1016/j.ajem.2021.06.074

8. Lee CC, Mankodi D, Shaharyar S, Ravindranathan S, Danckers M, Herscovici P, et al. High flow nasal cannula versus conventional oxygen therapy and non-invasive ventilation in adults with acute hypoxemic respiratory failure: A systematic review. Respir Med. 2016;121:100–

   8. https://doi.org/ 10.1016/j.rmed.2016.11.004

9. Yin X, Xu W, Zhang J, Wang M, Chen Z, Liu S, et al. High-Flow Nasal Oxygen versus Conventional Nasal Cannula in Preventing Hypoxemia in Elderly Patients Undergoing Gastroscopy with Sedation: A Randomi- zed Controlled Trial. Int J Med Sci. 2024;21(5):914–20. https://doi.org/10.7150/ijms.91607

10. Ma J, Tan L. Research Progress on Prevention and Treatment of Hypoxemia in Painless Gastroscopy: A

    Review Article. Asploro J Biomed Clin Case Rep. 2023 Apr 8;6(2):54–63. https://doi.org/ 10.36502/2023/ ASJBCCR.6291

11. Wang L, Zhang Y, Han D, Wei M, Zhang J, Cheng X, et al. Effect of high flow nasal cannula oxygenation on incidence of hypoxia during sedated gastrointestinal endoscopy in patients with obesity: multicentre ran- domised controlled trial. BMJ. 2025;e080795. https:// doi.org/10.1136/bmj-2024-080795

12. Qadeer MA, Lopez AR, Dumot JA, Vargo JJ. Hypoxemia du- ring Moderate Sedation for Gastrointestinal Endoscopy: Causes and Associations. Digestion. 2011;84(1):37–45. https://doi.org/10.1159/000321621

13. Wei C, Ma S, Jiang L, Wang J, Yuan L, Wang Y. A meta-analysis of the effects of transnasal high-flow oxygen therapy in gastrointestinal endoscopy. Front Med. 2024;10:11. https://doi.org/10.3389/fmed.2024.1419635

14. Saksitthichok B, Petnak T, So-ngem A, Boonsamgsuk V. A prospective randomized comparative study of high- flow nasal cannula oxygen and non-invasive ventilati- on in hypoxemic patients undergoing diagnostic flexi- ble bronchoscopy. J Thorac Dis. 2019;11(5):1929–39. https://doi.org/10.21037/jtd.2019.05.02

15. Arias-Sanchez P, Ledesma G, Cobos J, Tirape H, Jara- millo B, Ruiz J, et al. Changes in Oxygen Saturation During Fiberoptic Bronchoscopy: High- Flow Nasal Cannula versus Standard Oxygen Therapy. Respir CARE. 2023;68(6):727–33. https://doi.org/ 10.4187/ respcare.10598

16. Chung S, Choi J, Lee Y, Choi J, Oh J, Min K, et al. Cli- nical Effectiveness of High-Flow Nasal Cannula in Hypoxaemic Patients during Bronchoscopic Procedu- res. Tuberc Respir Dis. 2019;82(1):81–5. https://doi. org/10.4046/trd.2017.0104

17. Kim SH, Bang S, Lee KY, Park SW, Park JY, Lee HS, et al. Comparison of high flow nasal oxygen and conventi- onal nasal cannula during gastrointestinal endoscopic sedation in the prone position: a randomized trial. Can J Anesth Can Anesth. 2021;68(4):460–6. https://doi. org/10.1007/s12630-020-01883-2

18. Lee S, Choi J, Chung I, Kim D, Sim W, Kim T. Compari- son of high-flow nasal cannula and conventional nasal cannula during sedation for endoscopic submucosal dissection: a retrospective study. Ther Adv Gastro- enterol. 2023;16:17562848231189957. https://doi. org/10.1177/17562848231189957

19. Wang L, Zhang Y, Han D, Wei M, Zhang J, Cheng X, et al. Effect of high flow nasal cannula oxygenation on incidence of hypoxia during sedated gastrointestinal endoscopy in patients with obesity: multicentre ran- domised controlled trial. BMJ. 2025;e080795. https:// doi.org/10.1136/bmj-2024-080795

20. Thiruvenkatarajan V, Sekhar V, Wong DT, Currie J, Van Wijk R, Ludbrook GL. Effect of high-flow nasal oxygen on hypoxaemia during procedural sedation: a systematic review and meta-analysis. Anaesthesia. 2023;78(1):81–

    92. https://doi.org/10.1111/anae.15845

    
    

21. Ayuse T, Kurata S, Mori T, Kuroda S, Ichinomiya T, Yano R, et al. Examination of stabilization of sedation by Nasal High Flow in patients with endoscopic retrograde cho- langiopancreatography during sedation using Dexmede- tomidine. Medicine (Baltimore). 2023;102(23):e34004. https://doi.org/10.1097/MD.0000000000034004

22. Mohamed AM, Selima WZ. HFNC Oxygen Therapy vs COT in Prolonged Upper Gastrointestinal Endosco- py Inside the ICU: A Prospective, Randomized, Con- trolled Clinical Study. Indian J Crit Care Med. 2025 Mar;29(3):223–9. https://doi.org/10.5005/jp-jour- nals-10071-24919

23. Tao Y, Sun M, Miao M, Han Y, Yang Y, Cong X, et al. High flow nasal cannula for patients undergoing bronchos- copy and gastrointestinal endoscopy: A systematic review and meta-analysis. Front Surg. 2022 Aug 15;9. https://doi.org/10.3390/jcm13010081

24. Teng WN, Ting CK, Wang YT, Hou MC, Chang WK, Tsou MY, et al. High-Flow Nasal Cannula and Mandibular Advan- cement Bite Block Decrease Hypoxic Events during Se- dative Esophagogastroduodenoscopy: A Randomized Clinical Trial. BioMed Res Int. 2019;2019:4206795. https://doi.org/10.1155/2019/4206795

25. Su CL, Chiang LL, Tam KW, Chen TT, Hu MC. High-flow nasal cannula for reducing hypoxemic events in pati- ents undergoing bronchoscopy: A systematic review and meta-analysis of randomized trials. PloS One. 2021;16(12):e0260716. https://doi.org/10.1371/jour- nal.pone.0260716

26. Zhaxi D, Ci D, Quan X, Laba C. High-flow nasal cannu- la oxygen reduced hypoxemia in patients undergoing gastroscopy under general anesthesia at ultra-high altitude: a randomized controlled trial. BMC Anesthesi- ol. 2024;24(1):189. https://doi.org/10.1186/s12871-

    024-02568-9

27. Luo X, Xiang F. High-flow nasal cannula oxygen the- rapy versus conventional oxygen therapy in pati- ents undergoing bronchoscopy: a retrospective stu- dy. BMC Pulm Med. 2024 Dec 18;24(1). https://doi. org/10.1186/s12890-024-03440-9

28. Yin X, Xu W, Zhang J, Wang M, Chen Z, Liu S, et al. High-Flow Nasal Oxygen versus Conventional Nasal Cannula in Preventing Hypoxemia in Elderly Patients Undergoing Gastroscopy with Sedation: A Randomi- zed Controlled Trial. Int J Med Sci. 2024;21(5):914–20. https://doi.org/10.7150/ijms.91607

29. Ben-Menachem E, McKenzie J, O’Sullivan C, Havryk AP. High-flow Nasal Oxygen Versus Standard Oxygen during Flexible Bronchoscopy in Lung Transplant Patients: A Randomized Controlled Trial. J Bronchol Interv Pulmonol. 2020;27(4):259–65. https://doi. org/10.1097/LBR.0000000000000670

30. Nay MA, Fromont L, Eugene A, Marcueyz JL, Mfam WS, Baert O, et al. High-flow nasal oxygenation or stan- dard oxygenation for gastrointestinal endoscopy with sedation in patients at risk of hypoxaemia: a multicen- tre randomised controlled trial (ODEPHI trial). Br J Ana-

    esth. 2021;127(1):133–42. https://doi.org/10.1016/j. bja.2021.03.020

31. Doulberis M, Sampsonas F, Papaefthymiou A, Karamo- uzos V, Lagadinou M, Karampitsakos T, et al. High-flow versus conventional nasal cannula oxygen supple- mentation therapy and risk of hypoxia in gastrointe- stinal endoscopies: a systematic review and meta- analysis. Expert Rev Respir Med. 2022;16(3):323–32. https://doi.org/10.1080/17476348.2022.2042256

32. Sampsonas F, Karamouzos V, Karampitsakos T, Papai- oannou O, Katsaras M, Lagadinou M, et al. High-Flow vs. Low-Flow Nasal Cannula in Reducing Hypoxemic Events During Bronchoscopic Procedures: A Systema- tic Review and Meta-Analysis. Front Med. 2022 Feb 24;9. https://doi.org/10.1371/journal.pone.0260716

33. Zhang W, Wang JL, Fu S, Zhou JM, Zhu YJ, Cai SN, et al. Incidence of oxygen desaturation using a high- flow nasal cannula versus a facemask during flexible bronchoscopy in patients at risk of hypoxemia: a rando- mised controlled trial. BMC Pulm Med. 2022;22(1):389. https://doi.org/10.1186/s12890-022-02188-4

34. Sawase H, Ozawa E, Yano H, Ichinomiya T, Yano R, Miyaaki H, et al. Respiratory support with nasal high flow without supplemental oxygen in patients un- dergoing endoscopic retrograde cholangiopancreato- graphy under moderate sedation: a prospective, ran- domized, single-center clinical trial. BMC Anesthesiol. 2023;23(1):156. https://doi.org/10.1186/s12871-

    023-02125-w

35. Lee C, Ju T, Lai P, Lin H, Huang Y. Should We Use High- Flow Nasal Cannula in Patients Receiving Gastro- intestinal Endoscopies? Critical Appraisals through Updated Meta-Analyses with Multiple Methodologies and Depiction of Certainty of Evidence. J Clin Med. 2022;11(13). https://doi.org/10.3390/jcm11133860

36. Zhang W, Yin H, Xu Y, Fang Z, Wang W, Zhang C, et al. The effect of varying inhaled oxygen concentrations of high- flow nasal cannula oxygen therapy during gastroscopy with propofol sedation in elderly patients: a randomized controlled study. BMC Anesthesiol. 2022;22(1):335. https://doi.org/10.1186/s12871-022-01879-z

37. Zhang Y, He X, Chen Y, Yang S. The effectiveness of high-flow nasal cannula during sedated digestive en- doscopy: a systematic review and meta-analysis. Eur J Med Res. 2022;27(1):30. https://doi.org/10.1186/ s40001-022-00661-8

38. Wei C, Ma S, Wang J, Yang N, Wang D, Yuan L, et al. The effectiveness of transnasal high flow nasal cannula in bronchoscopy under sedation: a systematic review and meta-analysis. Front Med. 2024;11. https://doi. org/10.3389/fmed.2024.1428431

39. Khanna P, Haritha D, Das A, Sarkar S, Roy A. Utility of high-flow nasal oxygen in comparison to conventional oxygen therapy during upper gastrointestinal endosco- pic procedures under sedation: A systematic review and meta-analyses. Indian J Gastroenterol. 2023;42(1):53–

    63. https://doi.org/10.1007/s12664-022-01308-6

    
    

40. Wang R, Li HC, Li XY, Tang X, Chu HW, Yuan X, et al. Modified high-flow nasal cannula oxygen therapy versus conventional oxygen therapy in patients un- dergoing bronchoscopy: a randomized clinical trial. BMC Pulm Med. 2021 Nov 14;21(1):367. https://doi. org/10.1186/s12890-021-01744-8

41. Feng Y, Chen Z, Wang J. Observation of choking reaction and other related indexes in elderly painless fiberoptic bronchoscopywithtransnasalhigh-flowhumidification oxygen therapy [Internet]. Open Med Pol. 2024;19(1). https://doi.org/10.1515/med-2024-1064 Available at: https://www.scopus.com/inward/record.uri?eid=2- s2.0-85210768968&doi=10.1515%2fmed-2024-

    1064&partnerID=40&md5=b7fa142308a0419b135 65540a9eb7f7d

42. Zhang W, Yuan X, Shen Y, Wang J, Xie K, Chen X. Op- timal flow of high-flow nasal cannula oxygenation to prevent desaturation during sedation for bronchos- copy: a randomized controlled study. Ther Adv Res- pir Dis. 2024;18:17534666241246637. https://doi. org/10.1177/17534666241246637

43. Kunder V, Harris J, Moody D. Comparative Effective- ness of High-Flow Nasal Cannula and Noninvasive Ventilation in Acute Hypoxemic Respiratory Failure: A Scoping Review. Cureus [Internet]. 2025. Available at: https://www.cureus.com/articles/363831-compa- rative-effectiveness-of-high-flow-nasal-cannula-and- noninvasive-ventilation-in-acute-hypoxemic-respira- tory-failure-a-scoping-review Accessed: 30.07.2025.

44. Qin J, Wang G, Liao Y, Shang W, Han D. High flow nasal therapy versus noninvasive ventilation for AECOPD with acute hypercapnic respiratory failure: a meta- analysis of randomized controlled trials. Ann Inten- sive Care. 2025;15(1):64. https://doi.org/10.1186/ s13613-025-01480-w

45. Su J, Tie X, Chen Y, Zou T, Yin W. Successful applica- tion of airway pressure release ventilation in a child with severe acute respiratory distress syndrome induced by trauma: a case report [Internet]. BMC Pulm Med. 2024;24(1). https://doi.org/10.1186/ s12890-024-02894-1 Available at: https:// www.scopus.com/inward/record.uri?eid=2-s2.0- 85185133376&doi=10.1186%2fs12890-024-

    02894-1&partnerID=40&md5=470aed98944debaf b05ccd9f4564128a

46. Lee CC, Mankodi D, Shaharyar S, Ravindranathan S, Danckers M, Herscovici P, et al. High flow nasal cannula versus conventional oxygen therapy and non-invasive ventilation in adults with acute hypoxe- mic respiratory failure: A systematic review. Respir Med. 2016;121:100–8. https://doi.org/10.1016/j. rmed.2016.11.004