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.
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;
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).
Crossover
Transoral nasal cannula oxygen delivery
Other interventionThe 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.
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.
Incidence of SpO2 <92%
Proportion of participants with peripheral oxygen saturation (SpO2) \<92% at any time during each oxygen delivery period.
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.
Time to achieve SpO2 >=95%
Time elapsed from the beginning of each intervention until peripheral oxygen saturation reaches \>=95%.
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.
Click on the lead sponsor to view all of their trials.
