Introduction to Oral Airways in Anesthesia
Oral airways are vital tools for maintaining airway patency in both emergency and controlled anesthesia settings. Anesthesiologists often rely on these devices to keep the airway open, prevent soft tissue obstruction, and facilitate other airway devices like endotracheal or supraglottic airways. Over time, various designs of oral airways have emerged, each with specific features and advantages.
In this article, we’ll explore the most commonly used oral airways, focusing on the Guedel, Berman, and Ovasapian airways, along with other specialized options. We’ll delve into their unique features, use cases, and key differences to help you make informed choices in clinical settings.
Why Oral Airways are Essential in Airway Management
Oral airways serve several critical functions in anesthesia and resuscitation:
- Maintaining airway patency: By preventing the tongue or soft palate from occluding the airway, they help keep the airway open, allowing for unimpeded ventilation.
- Facilitating ventilation: They allow unobstructed passage of air or supplemental oxygen through the oropharynx.
- Assisting with intubation: Some oral airways, like the Ovasapian, are designed specifically to assist in fiberoptic intubation.
The right oral airway can make a significant difference in a procedure’s success and patient safety, as improper airway management can lead to hypoxia, brain damage, or even death.
Types of Oral Airways
Oral airways come in different shapes, sizes, and materials. Here are the key types used in anesthesia:
Guedel Airways
Inventor: Arthur Guedel, an American anesthesiologist
Design: A hollow, tubular design with a bite block
Purpose: General airway patency
The Guedel airway is a widely used and classic choice. It has a simple tubular shape, with a rigid outer wall and a central channel that allows for airflow and the passage of suction catheters if necessary. The Guedel is usually made of semi-rigid plastic and is designed to keep the tongue away from the posterior pharynx, preventing airway obstruction.
Pros:
- Easy to insert and position
- Provides a clear path for ventilation and suctioning
- Protects against occlusion from biting, thanks to its integrated bite block
Cons:
- Can cause soft tissue injury if improperly sized
- Not ideal for intubation guidance
Berman Airways
Inventor: Initially developed by Warren Berman
Design: A split-channel design with lateral grooves
Purpose: Oral airway management and assistance with fiberoptic intubation
The Berman airway is distinguishable by its lateral channels or “grooves.” This open design allows for the insertion of a fiberoptic bronchoscope or endotracheal tube while maintaining airway patency. The grooves also provide additional flexibility in airway management, making it suitable for a range of scenarios.
Pros:
- Open channels allow for suctioning and visualization
- Can be used as an aid for fiberoptic intubation
- Less likely to occlude due to secretions
Cons:
- Bulkier than the Guedel airway
- May require more training to use effectively in intubation scenarios
Ovasapian Airways
Inventor: Anthony Ovasapian, a pioneer in fiberoptic intubation
Design: A unique design tailored for fiberoptic intubation
Purpose: Primarily for facilitating fiberoptic-guided intubations
The Ovasapian airway was specifically designed to aid in fiberoptic intubations. Its concave shape and hollow center channel provide a clear path for the bronchoscope or endotracheal tube. Unlike the Berman or Guedel, this airway has a distinct flared end to stabilize it within the mouth during fiberoptic procedures.
Pros:
- Excellent for fiberoptic intubation in difficult airways
- Stabilizes the fiberoptic scope, reducing the risk of airway trauma
- Allows continuous oxygenation during intubation attempts
Cons:
- Limited use outside of fiberoptic intubation
- May cause trauma if used improperly
Williams Airways
Design: Partially enclosed tubular design with an open side
Purpose: Supraglottic airway management and fiberoptic intubation
The Williams airway is another option commonly used for fiberoptic intubation. It has a partially closed tube with one open side, allowing for the insertion of fiberoptic equipment or endotracheal tubes. It’s particularly useful in managing challenging airways where direct visualization is required.
Pros:
- Versatile; can be used for ventilation and intubation
- Excellent for fiberoptic-assisted procedures
Cons:
- Not suitable for standard ventilation
- Can be challenging for novice users
Other Specialized Oral Airways
Other types of oral airways are available, each with specific applications:
- Nasal Trumpet (Nasopharyngeal Airway): Used for nasopharyngeal access, particularly in patients with oral trauma or trismus.
- Esophageal Obturator Airway (EOA): Less commonly used today, it was once employed in emergency settings but has largely been replaced by supraglottic devices.
- King LT Airway: Though technically a supraglottic airway, it is designed for ease of insertion in emergencies.
Comparing Oral Airways: Key Features
| Airway Type | Main Use | Advantages | Disadvantages |
|---|---|---|---|
| Guedel | General airway patency | Easy to use, bite protection | Limited use in intubation |
| Berman | General & fiberoptic aid | Lateral channels for suction and bronchoscopy | Bulkier, requires training |
| Ovasapian | Fiberoptic intubation aid | Stabilizes scope, good for oxygenation during intubation | Limited use outside intubation |
| Williams | Fiberoptic & supraglottic | Versatile for ventilation/intubation | Challenging for beginners |
| Nasal Trumpet | Nasopharyngeal patency | Useful with oral trauma | Risk of nasal injury |
Choosing the Right Oral Airway
Selecting the appropriate oral airway depends on several factors:
- Purpose: If you’re looking for a general-purpose airway, a Guedel may suffice. For fiberoptic intubation, an Ovasapian or Williams would be better suited.
- Patient’s Anatomy: Consider the patient’s oral and pharyngeal anatomy, as certain airways may cause trauma or discomfort in smaller patients.
- Clinical Setting: In emergencies, ease of insertion is crucial. The Guedel and Berman airways are often faster to deploy.
- Skill Level: More advanced airways like the Williams may require training, making them less ideal for rapid use in urgent scenarios.
Oral Airways are Not Bite Blocks
The human dental arrangement is a result of evolutionary adaptation, optimizing the mouth for both cutting at the front and grinding at the back. Incisors and canines handle the cutting and tearing of food, while premolars and molars specialize in grinding it down.
Placing a bite block in the back of the mouth by the molars provides maximal leverage and protection during medical procedures for several key reasons:
Maximal Biting Force at the Molars
- Lever Mechanics of the Jaw: The human jaw functions like a lever, with the temporomandibular joint (TMJ) acting as the fulcrum. The molars are closest to this fulcrum.
- Stronger Force Generation: Because of their proximity to the fulcrum, the molars can exert a stronger biting force than the front teeth (incisors and canines).
- Effective Force Absorption: Placing the bite block at the molars allows it to absorb and withstand the maximum potential force generated by the jaw muscles.
Protection of Airway Devices
- Preventing Tube Occlusion: For patients with airway devices like endotracheal tubes, a bite block by the molars prevents them from biting down and occluding these tubes.
- Reducing Risk of Dislodgement: It helps maintain the position of airway devices by minimizing movement caused by involuntary biting or clenching.
Preservation of Dental Structures
- Molars Designed for Force: Molars have broader surfaces and stronger roots to handle significant pressure during chewing.
- Preventing Dental Damage: Placing the bite block at the molars reduces the risk of damaging more delicate front teeth, which are not designed to withstand heavy forces.
- Even Force Distribution: It helps distribute the biting force evenly across the stronger teeth, minimizing the risk of tooth fractures or dislodgement.
Enhanced Patient Safety and Comfort
- Minimizing Gag Reflex: Positioning the bite block at the back reduces the likelihood of stimulating the gag reflex compared to placing it near the front of the mouth.
- Comfortable Fit: The bite block is more securely and comfortably placed in the molar area, which is less intrusive for the patient.
Efficient Muscle Relaxation
- Targeting the Masseter Muscle: The masseter muscle, one of the main muscles responsible for chewing, exerts its force primarily at the molars.
- Reducing Muscle Strain: A bite block placed at the molars can help relax the jaw muscles by providing a counterforce, reducing the risk of muscle cramps or spasms.
Placing a bite block by the molars maximizes leverage due to the jaw’s anatomical and mechanical properties. It ensures that the device can effectively absorb the strongest biting forces, protects the patient’s teeth and any airway equipment, and enhances overall safety and comfort during medical procedures. This strategic placement leverages the jaw’s natural design to provide optimal protection and efficiency.
Patient Safety Considerations in Oral Airway Use
Ensuring patient safety is paramount in airway management. Here are some key considerations:
- Sizing: The correct size is essential to prevent trauma or airway obstruction.
- Insertion Technique: Avoiding forceful insertion can reduce the risk of tissue damage.
- Monitoring: Continuous monitoring of oxygenation and ventilation is crucial, especially during intubation.
- Sterility and Hygiene: Ensure proper cleaning and sterilization between uses to prevent infection.
As the American Society of Anesthesiologists noted, “Maintaining airway patency is one of the most critical responsibilities in anesthesia” (ASA Guidelines).
Summary
In summary, here’s a quick recap of the main types of oral airways:
- Guedel: Simple, reliable for general use
- Berman: Split-channel, suitable for fiberoptic or suction catheters
- Ovasapian: Designed for fiberoptic intubation
- Williams: Versatile but requires skill
Each airway has unique features that suit specific clinical needs. The right choice can make airway management smoother and safer.
References
- American Society of Anesthesiologists. Practice Guidelines for Management of the Difficult Airway. Available at: ASA
- Hagberg CA, Benumof JL. **Benumof and Hagberg’sAirway Management**. Philadelphia, PA: Elsevier; 2007.
- Miller RD, Eriksson LI, Fleisher LA, et al. Miller’s Anesthesia. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014.
By carefully selecting the correct oral airway and using it appropriately, anesthesiologists can significantly improve patient outcomes and minimize risks during airway management.
