Comparing high-flow nasal oxygen flow rates with a face mask before anesthesia in obesity
Tests nasal oxygen at two flow rates against a face mask in adults with obesity.
Plain-language title generated from the registry record
Registry title: Effect of Different-Flow High-Flow Nasal Cannula Versus Traditional Face Mask Oxygenation on Safe Apnea Time in Obese Patients
Key facts
- Where
- Lianyungang, ChinaSee the site
Could this be for you?
Answer for yourself. This is not a decision: only the study team can say whether you can take part.
- Are you between 18 and 65 years old?
Source: NCT07843810, who can take part
Where in China
- The First People's Hospital of LianyungangLianyungang, ChinaNo longer taking part
Questions to ask the study team
- How often do I need to come in, and for how long each time?
- Are travel costs paid?
- Can I keep my own doctor?
- What happens if I want to stop?
Trial details
- Who runs it
- The First People's Hospital of Lianyungang
- Trial code
- NCT07843810
- Record updated
- 28 September 2026
- Original description
Obesity is a growing global health problem, and patients with obesity are at higher risk of hypoxemia during induction of general anesthesia. This is because excess body weight reduces the lungs' oxygen storage capacity, causing blood oxygen saturation to decline faster than in normal-weight individuals once breathing stops. Currently, the most common preventive method is preoxygenation with a face mask delivering 100% oxygen for several minutes before anesthesia induction. However, face masks often fail to seal properly in obese patients, potentially compromising preoxygenation effectiveness.Read full original descriptionShow less
Effect of Different-Flow High-Flow Nasal Cannula Versus Traditional Face Mask Oxygenation on Safe Apnea Time in Obese Patients: A Prospective Randomized Controlled Trial
Obesity is a growing global health problem, and patients with obesity are at higher risk of hypoxemia during induction of general anesthesia. This is because excess body weight reduces the lungs' oxygen storage capacity, causing blood oxygen saturation to decline faster than in normal-weight individuals once breathing stops. Currently, the most common preventive method is preoxygenation with a face mask delivering 100% oxygen for several minutes before anesthesia induction. However, face masks often fail to seal properly in obese patients, potentially compromising preoxygenation effectiveness.
High-flow nasal oxygen therapy is a newer technique that delivers heated and humidified oxygen at high flow rates through nasal cannulae. It not only provides effective preoxygenation but may also continue to supply oxygen during apnea (apneic oxygenation), thereby prolonging the safe apnea time. Nevertheless, it remains unclear which flow rate is most effective and whether high-flow nasal oxygen is truly superior to conventional face masks.
This prospective randomized controlled trial will enroll 147 obese patients (BMI ≥ 28kg/m²) scheduled for elective surgery at Lianyungang First People's Hospital. Participants will be randomly assigned to one of three groups: (1) traditional face mask preoxygenation at 15 L/min, (2) high-flow nasal oxygen at 45 L/min, or (3) high-flow nasal oxygen at 70 L/min. All patients will receive 100% oxygen for 3 minutes. The primary outcome is safe apnea time - the duration from cessation of breathing until SpO₂ drops to 93%. Secondary outcomes include arterial blood gas values, patient comfort during preoxygenation, tolerance rate, and hemodynamic stability.
The study hypothesis is that high-flow nasal oxygen at 70 L/min will provide a longer safe apnea time than both traditional face mask preoxygenation and high-flow nasal oxygen at 45 L/min in obese patients. The results will provide high-quality evidence for optimizing perioperative preoxygenation strategies in this population.
Inclusion: Age 18 to 65 years; American Society of Anesthesiologists (ASA) physical status I ~ III; Scheduled for elective surgery under general anesthesia with endotracheal intubation; Body mass index (BMI) ≥ 28 kg/m²; Willing and able to provide written informed consent.
Exclusion: Current smoker or former smoker who quit less than 1 year prior to enrollment; Participation in another interventional clinical trial within 30 days prior to enrollment; Cardiac disease including ischemic heart disease, heart failure (New York Heart Association class ≥ 2), current arrhythmia, or pulmonary hypertension; Severe asthma or moderate to severe chronic obstructive pulmonary disease; Severe nasal obstructive disease that affects nasal ventilation or intubation; Pregnancy; Baseline peripheral oxygen saturation (SpO₂) < 95%; Known or anticipated difficult airway.