To the Editor
We are writing to introduce and discuss the Capnography Monitoring Bite Block Oxygenation (COMBO) endoscopy oropharyngeal airway, a novel airway management device with integrated capnography monitoring and dual oxygenation support. This device was developed to address persistent challenges in maintaining airway patency and oxygenation during esophagogastroduodenoscopy (EGD) under propofol sedation. Hypoxia remains a common complication, even with supplemental oxygen via nasal cannulas.1 While high-flow nasal oxygen and supraglottic jet oxygenation offer potential solutions, their effectiveness depends on ensuring airway patency—a goal hindered by tongue base collapse, the most common cause of airway obstruction during sedation.
Methods to address tongue base collapse include jaw thrust, nasopharyngeal airways, and oropharyngeal airways. However, these approaches have notable limitations: jaw thrust is labor-intensive for health care providers and often inconsistent; nasopharyngeal airways carry a risk of nasal bleeding; and conventional oropharyngeal airways obstruct endoscope insertion, limiting their use in endoscopic procedures. Although a new oropharyngeal airway can allow gastroscopy to pass through, it lacks capnography monitoring so that cannot avoid severe hypoxia.2
To overcome these limitations, Professor Diansan Su developed the COMBO endoscopy oropharyngeal airway. This multifunctional device (Figure) integrates a bite block, capnography monitoring, oxygenation support, and an innovative oropharyngeal airway design. The Video can provide the detailed process of the operation. Key features include the following:
- Modified bite block: Designed to secure the nasal cannula for preoxygenation, the bite block also features an ergonomic structure made from soft, medical-grade polymer to minimize mucosal trauma.
- Endoscopy channel: The airway incorporates an open longitudinal gastroscope channel on its convex surface, coated with a hydrophilic material to facilitate smooth insertion and movement of the endoscope.
- Dual oxygenation and capnography monitoring: The device includes oxygen supply and end-tidal carbon dioxide (CO₂) sampling channels positioned near the glottis, ensuring efficient oxygen delivery and accurate capnography readings.
- Supraglottic jet ventilation capability: The oxygen supply channel is compatible with a jet ventilation device, enabling supraglottic jet oxygenation and ventilation. This feature provides an additional safety net for maintaining oxygenation in challenging scenarios.
The COMBO device has received regulatory approval in China (Shanghai Equipment Registration No. 20232080037) and shows significant potential for improving patient safety during gastrointestinal endoscopic procedures. A multicenter study (NCT06081647) is currently underway to evaluate its efficacy and safety in reducing hypoxia during gastrointestinal endoscopy under propofol sedation. Preliminary findings from a study involving 12 obese patients have been promising. For instance, in a severely obese patient (body mass index [BMI] = 38.3), SpO₂ levels were maintained between 90% and 93% without manual intervention.
While the COMBO endoscopy oropharyngeal airway offers several advantages, challenges such as cost could limit its initial adoption. Key benefits and considerations include:
ADVANTAGES
- Enhanced oxygenation: The dual oxygen supply channels deliver oxygen more effectively than conventional methods,3 and the jet device provides an option for optimal oxygenation.
- Accurate capnography: The modified CO₂ sampling channels enable precise monitoring, improving patient safety.4,5
- Improved endoscope navigation: The hydrophilic coating on the gastroscope channel ensures smooth movement, even with simple water moistening.
- Patient safety: The device’s design minimizes airway obstruction, making it particularly beneficial for obese patients.
- Supraglottic jet oxygenation: The ability to provide supraglottic jet ventilation adds versatility and enhances airway management during complex cases.
DISADVANTAGES
- Risk of nausea: Suboptimal sedation levels may lead to nausea and increased oral secretions. To minimize these risks, it is recommended to first place the bite block correctly and then sedate the patient. Once an adequate depth of sedation is achieved, the oropharyngeal airway can be inserted, reducing discomfort and the likelihood of nausea.
We believe the COMBO device’s introduction represents a significant advancement in airway management during gastrointestinal endoscopy. A broader discussion within the medical community will help refine its application and address potential limitations, ensuring its optimal use in clinical practice. We hope this communication fosters further research and dialogue to enhance patient care.
Yueying Zheng
Department of Anesthesiology
The First Affiliated Hospital
Zhejiang University School of Medicine
Hangzhou, Zhejiang Province, China
Shaohui Guo
Department of Anesthesiology
The First Affiliated Hospital
Zhejiang University School of Medicine
Hangzhou, Zhejiang Province, China
Yuhan Zhang
Department of Anesthesiology
Renji Hospital
Shanghai Jiaotong University School of Medicine
Shanghai, China
Diansan Su
Department of Anesthesiology
The First Affiliated Hospital
Zhejiang University School of Medicine
Hangzhou, Zhejiang Province, China
diansansu@zju.edu.cn