Postoperative HypoxemiaNCT07841223
Transoral Nasal Cannula Oxygen Therapy for Mouth-Breathing Patients in the Postanesthesia Care Unit
A study testing Transoral nasal cannula oxygen delivery in people with Postoperative Hypoxemia, run by Nanjing First Hospital, Nanjing Medical University at 1 site in China.
Trial summary
Postoperative hypoxemia is a common complication in the postanesthesia care unit (PACU). Patients who breathe through the mouth after tracheal extubation may receive limited benefit from standard nasal cannula oxygen therapy, because the nasal cavity functions as an ineffective dead space during mouth breathing. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Postoperative Hypoxemia
- What is being tested?
- Transoral nasal cannula oxygen delivery
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 64 participants
- Where
- 1 siteChina
- Study dates
- 8 Oct 2026to 31 Dec 2027
- Phase
- Interventional
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Aged older than 18 years;
- American Society of Anesthesiologists (ASA) physical status classification I-III;
- Undergoing elective thoracic or abdominal surgery under general anesthesia with postoperative transfer to the postanesthesia care unit (PACU);
- Anticipated PACU stay of at least 30 minutes to allow an adequate observation window for data collection;
- Recovery of spontaneous breathing after tracheal extubation, and confirmed as persistent mouth breathing by the standardized three-step assessment procedure (visual screening, cotton-fiber airflow verification, and mirror confirmation);
- Written informed consent signed by the patient or a family member.
Who cannot join
- Preoperative diagnosis of severe obstructive sleep apnea-hypopnea syndrome (apnea-hypopnea index [AHI] >30) or requirement for continuous positive airway pressure therapy;
- Severe hypoxemia requiring immediate escalation of oxygen therapy (SpO2 <90% or PaO2 <60 mmHg);
- Requirement for reintubation or placement of an oropharyngeal or nasopharyngeal airway after surgery;
- Hemodynamic instability requiring vasoactive agents to maintain mean arterial pressure (MAP <65 mmHg).
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
YING ZHANG contact
China1 site, 1 recruiting
- Recruiting
Nanjing First Hospital, Nanjing Medical University
Nanjing, Jaingsu, 210006
Shuai Wang, +8618852095101, wangshuaisj@126.com
About this study
Official title: Transoral Nasal Cannula Oxygen Delivery on Postoperative Hypoxemia for Mouth-breathing Patients After Surgery: a Randomized Controlled Crossover Trial
Postoperative hypoxemia is a common complication in the postanesthesia care unit (PACU). Patients who breathe through the mouth after tracheal extubation may receive limited benefit from standard nasal cannula oxygen therapy, because the nasal cavity functions as an ineffective dead space during mouth breathing. Clinical observations suggest that placing the prongs of a nasal cannula inside the mouth (transoral oxygen delivery) rapidly improves oxygenation in these patients. However, no randomized controlled trial has formally verified this effect.
This single-center, randomized, controlled, crossover trial will enroll 64 adult patients identified as persistent mouth breathers after extubation in the PACU following elective thoracic or abdominal surgery under general anesthesia. Each participant will receive, in a randomized sequence, both standard nasal cannula oxygen delivery (4 L/min for 10 minutes) and transoral nasal cannula oxygen delivery (4 L/min for 10 minutes), separated by a 5-minute washout period, so that each participant serves as his or her own control.
The primary outcome is the incidence of hypoxemia (peripheral oxygen saturation [SpO2] <90% sustained for at least 10 seconds, or oxygenation index [PaO2/FiO2 ratio] <300 mmHg) during each oxygen delivery period. Secondary outcomes include the incidence of SpO2 <92%, time to achieve SpO2 >=95%, oxygenation index measured by arterial blood gas analysis, need for escalation of oxygen therapy, vital signs, patient comfort and adverse effects, PACU length of stay, and respiratory complications within 24 hours after surgery. The results are expected to provide high-level evidence for optimizing oxygen therapy strategies for mouth-breathing patients in the PACU.
Read the detailed description
This is a single-center, randomized, controlled, crossover trial conducted in the Department of Anesthesiology, Pain and Perioperative Medicine, Nanjing First Hospital, Nanjing Medical University, China.
Screening and assessment of mouth breathing: Adult patients recovering from general anesthesia for elective thoracic or abdominal surgery are assessed 5 minutes after tracheal extubation using a standardized three-step procedure: (1) visual screening (lip separation >0.5 cm, visible anterior teeth, and lowered mandibular position, observed for 0-10 s); (2) airflow verification using cotton fiber wisps placed approximately 1 cm in front of both nostrils and the lips to identify the dominant ventilation pathway (10-25 s); and (3) mirror confirmation of exhaled vapor condensation together with observation of tongue position (25-40 s). Persistent mouth breathing is confirmed when all three steps are positive and no spontaneous mouth closure lasting more than 3 seconds occurs during the 40-second observation period.
Interventions: (a) Standard nasal cannula oxygen delivery: a standard dual-prong nasal cannula is placed in both nostrils with an oxygen flow of 4 L/min for 10 minutes. (b) Transoral nasal cannula oxygen delivery: the two prongs of the same nasal cannula are joined and placed in the oral vestibule at the inner aspect of the mouth corner (approximately at the buccal mucosa corresponding to the first molar), to a depth of no more than 3 cm, with an oxygen flow of 4 L/min for 10 minutes. A 5-minute washout period, during which nasal oxygen delivery is resumed, separates the two intervention periods.
Randomization and sequence: Eligible participants are randomly assigned in a 1:1 ratio to one of two sequences. Sequence A (nasal first): nasal oxygen delivery for 10 minutes, 5-minute washout, then transoral oxygen delivery for 10 minutes. Sequence B (transoral first): transoral oxygen delivery for 10 minutes, 5-minute washout, then nasal oxygen delivery for 10 minutes.
Measurements: SpO2 is monitored continuously throughout all periods. Arterial blood gas is sampled at minute 10 of each intervention period through the indwelling radial arterial catheter placed for routine intraoperative monitoring (approximately 1 mL per sample) to calculate the oxygenation index (PaO2/FiO2 ratio). Vital signs, comfort scores, and adverse effects are recorded at predefined time points.
Safety management: Continuous pulse oximetry is maintained throughout the study. Predefined safety exit criteria are applied (e.g., SpO2 <85% sustained for more than 2 minutes, or SpO2 <88% during any intervention); oxygen therapy is escalated immediately (face mask, reservoir mask, high-flow nasal cannula, or noninvasive ventilation) whenever clinically indicated, and an anesthesiologist is present in the PACU at all times. The same cannula is disinfected with cotton swabs when switched between the nasal and oral routes to prevent cross-infection.
- Conditions
- Postoperative Hypoxemia
- Being tested
- Transoral nasal cannula oxygen delivery
- Keywords
- Nasal cannula, Transoral oxygen delivery, Postanesthesia care unit (PACU), Oxygen therapy, Crossover trial, Pulse oximetry (SpO2), Oxygenation index
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Transoral nasal cannula oxygen deliveryOther
The two prongs of a standard dual-prong nasal cannula are joined and placed in the oral vestibule at the inner aspect of the mouth corner (approximately at the buccal mucosa corresponding to the first molar), to a depth of no more than 3 cm to avoid stimulating the gag reflex. Oxygen flow is set at 4 L/min with standard humidification for 10 minutes.
| Study group | Role | What they receive |
|---|---|---|
| Sequence ON: Transoral oxygen first, then nasal oxygen | Active comparator | Participants receive transoral nasal cannula oxygen delivery (4 L/min for 10 minutes), followed by a 5-minute washout period (nasal oxygen delivery resumed), and then standard nasal cannula oxygen delivery (4 L/min for 10 minutes). Receives: Other: Transoral nasal cannula oxygen delivery |
| Sequence NO: Nasal oxygen first, then transoral oxygen | Active comparator | Participants receive standard nasal cannula oxygen delivery (4 L/min for 10 minutes), followed by a 5-minute washout period (nasal oxygen delivery resumed), and then transoral nasal cannula oxygen delivery (4 L/min for 10 minutes). Receives: Other: Transoral nasal cannula oxygen delivery |
What is being measured
The primary outcome is the main question the study is designed to answer.
Incidence of hypoxemia during the oxygen delivery periods
Hypoxemia is defined as peripheral oxygen saturation (SpO2) <90% sustained for at least 10 seconds, or an oxygenation index (PaO2/FiO2 ratio) <300 mmHg measured by arterial blood gas analysis at minute 10 of the intervention period. The outcome is reported as the proportion of participants experiencing hypoxemia during the nasal oxygen delivery period compared with the transoral oxygen delivery period.
Measured: During each 10-minute oxygen delivery period in the PACU (each participant undergoes two consecutive intervention periods)
Secondary outcomes (14)
Incidence of SpO2 <92%
Proportion of participants with peripheral oxygen saturation (SpO2) <92% at any time during each oxygen delivery period.
Measured: During each 10-minute oxygen delivery period in the PACU
Oxygenation index (PaO2/FiO2 ratio)
Calculated from arterial blood gas sampled through the indwelling radial arterial catheter at minute 10 of each intervention period; compared between the nasal and transoral oxygen delivery periods.
Measured: At minute 10 of each 10-minute oxygen delivery period
Time to achieve SpO2 >=95%
Time elapsed from the beginning of each intervention until peripheral oxygen saturation reaches >=95%.
Measured: From the start of each oxygen delivery period, up to 10 minutes
Proportion of participants requiring escalation of oxygen therapy
Proportion of participants requiring escalation to a simple face mask (>=6 L/min), reservoir mask, high-flow nasal cannula (HFNC), or noninvasive ventilation (NIV) because of SpO2 <90% or respiratory distress.
Measured: Throughout the PACU stay (up to 24 hours after surgery)
Respiratory rate
Respiratory rate (breaths/min) recorded at each predefined time point.
Measured: Preoperatively; at the start of surgery; at the end of surgery; after extubation; 1 minute before and 1 minute after each change of oxygen delivery route; at PACU discharge
Heart rate
Heart rate (beats/min) recorded at each predefined time point.
Measured: Preoperatively; at the start of surgery; at the end of surgery; after extubation; 1 minute before and 1 minute after each change of oxygen delivery route; at PACU discharge
Mean arterial pressure (MAP)
Mean arterial pressure (mmHg) recorded at each predefined time point.
Measured: Preoperatively; at the start of surgery; at the end of surgery; after extubation; 1 minute before and 1 minute after each change of oxygen delivery route; at PACU discharge
Airway plateau pressure
Airway plateau pressure (cmH2O) recorded from the anesthesia ventilator.
Measured: At the start and at the end of surgery
Positive end-expiratory pressure (PEEP)
Positive end-expiratory pressure (cmH2O) recorded from the anesthesia ventilator.
Measured: At the start and at the end of surgery
Oral dryness score
Oral dryness assessed with a visual analog scale (VAS) ranging from 0 to 10, where 0 indicates no dryness and 10 indicates the worst imaginable dryness. Higher scores indicate worse (more severe) dryness.
Measured: Immediately after completion of each 10-minute oxygen delivery period
Overall comfort score
Overall comfort assessed with a visual analog scale (VAS) ranging from 0 to 10, where 0 indicates maximal discomfort and 10 indicates maximal comfort. Higher scores indicate better comfort.
Measured: Immediately after completion of each 10-minute oxygen delivery period
Pharyngeal irritation / nausea score
Patient-reported pharyngeal irritation and nausea, each graded on a 4-point scale: 0 = none, 1 = mild (symptoms present but tolerable), 2 = moderate (causing discomfort but not requiring intervention), 3 = severe (requiring intervention). Higher scores indicate worse symptoms.
Measured: Immediately after completion of each 10-minute oxygen delivery period
Length of PACU stay
Total duration of stay in the postanesthesia care unit, in minutes.
Measured: From PACU admission to PACU discharge (up to 24 hours after surgery)
Respiratory complications within 24 hours after surgery
Composite of reintubation, pneumonia, atelectasis, and requirement for prolonged oxygen therapy, reported as the number and proportion of participants with each event.
Measured: Within 24 hours after surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Sep 2026
- Study start8 Oct 2026
- Primary completion1 Dec 2027 (estimated)
- Study completion31 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Postoperative HypoxemiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 64 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Nanjing First Hospital, Nanjing Medical University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Shuai Wang, Nanjing First Hospital, Nanjing Medical University
- Investigators
- Shuai Wang, Principal investigator, Nanjing First Hospital, Nanjing Medical University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07841223
- Sponsor's protocol ID
- KY20260723-02
- Status last verified
- Oct 2026
- First submitted
- 15 Sep 2026
- Last updated
- 9 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: All data relevant to the study are included in the article. Data supporting the findings are available from the corresponding author upon reasonable request.