Introduction to the i-gel as an Intubation Conduit
The i-gel® is a second-generation supraglottic airway device (SAD) distinctive for its soft, non-inflatable cuff made from a gel-like thermoplastic elastomer [1.5.3]. This material is designed to mirror the perilaryngeal anatomy, creating a seal without the need for cuff inflation, which can simplify and speed up insertion [1.8.6, 1.5.3]. Initially introduced as a ventilation device, its wide, short airway channel has made it a popular option for use as a conduit for passing an endotracheal tube (ETT), particularly in difficult airway scenarios or as a rescue technique [1.2.1, 1.8.3]. Unlike some other intubating SADs, such as the Intubating Laryngeal Mask Airway (ILMA), the i-gel does not have a specifically designed ETT, leading to studies on which commercially available tubes perform best [1.2.1]. Its design includes several features that are advantageous for intubation, such as an epiglottic rest to prevent airway obstruction and buccal cavity stabilization to reduce rotation [1.8.4].
Techniques for Intubating Through an i-gel
Intubation through an i-gel can be performed using two primary methods: blind intubation or fiberoptic-guided intubation. The general procedure begins with standard i-gel insertion.
Standard i-gel Insertion Procedure
- Preparation: Select the correct i-gel size based on the patient's weight [1.3.2]. Prepare equipment including suction, lubricant, and an ETCO2 monitor [1.3.4].
- Lubrication: Apply a water-based lubricant to the back, front, and sides of the i-gel's cuff [1.3.2].
- Positioning: Place the patient in the "sniffing" position (head extended, neck flexed) and gently press down on the chin [1.3.2].
- Insertion: Introduce the soft tip of the i-gel into the mouth, gliding it along the hard palate until definitive resistance is felt [1.3.2].
- Confirmation: Confirm placement by ventilating and observing for adequate chest rise and a square waveform on the capnograph [1.3.4].
Fiberoptic-Guided Intubation
Fiberoptic-guided intubation is generally considered the more successful and safer method. Studies have shown that using a fiberoptic bronchoscope (FOB) can significantly improve success rates, with some studies reporting up to 100% success, even in patients with predictors of a difficult airway [1.2.1, 1.5.1]. The wide channel of the i-gel often provides a good to excellent view of the glottic opening [1.5.1, 1.5.6]. The technique involves passing the lubricated FOB through the i-gel's airway channel to visualize the vocal cords, advancing the scope into the trachea, and then railroading a pre-loaded ETT over the scope.
Blind Intubation
Blind intubation through an i-gel is also possible but has a more variable and generally lower success rate compared to fiberoptic-guided methods [1.2.3]. Success rates for blind intubation have been reported in various studies, with first-attempt success ranging from as low as 15% in difficult airways to around 66-69% in elective cases [1.2.1, 1.2.3]. The overall success rate is often lower than with devices specifically designed for blind intubation, like the LMA Fastrach® [1.4.1, 1.4.4]. Maneuvers such as lateral displacement of the larynx can sometimes improve the success rate [1.2.1]. However, blind techniques carry a higher risk of esophageal intubation or airway trauma [1.8.1].
Success Rates and Choice of Endotracheal Tube
The choice of endotracheal tube significantly impacts the success of intubation through an i-gel. Since the i-gel does not have a designated tube, clinicians must choose from standard available options.
One study directly compared Polyvinyl chloride (PVC), Intubating Laryngeal Mask Airway (ILMA), and flexometallic ETTs for blind intubation via an i-gel [1.2.1].
- PVC ETTs: These tubes demonstrated the highest first-attempt (68%) and overall (88%) success rates. The study concluded that the inbuilt curvature of the PVC tube helps direct it toward the laryngeal inlet after exiting the i-gel [1.2.1].
- ILMA ETTs: These are straight, floppy tubes that, while passing easily through the i-gel, had more difficulty navigating through the vocal cords, resulting in lower success rates [1.2.1].
- Flexometallic ETTs: These also showed lower success rates compared to PVC tubes [1.2.1].
Fiberoptic-guided intubation through the i-gel generally yields much higher success rates, often equivalent to or better than other SADs [1.5.1]. When using a fiberoptic scope, the i-gel has been shown to provide a better view of the glottis compared to the LMA-Fastrach™ [1.5.1].
Comparison with Other Supraglottic Airways
The i-gel's performance as an intubation conduit is often compared to the LMA Fastrach®, which is considered a gold standard for blind intubation through a SAD [1.4.1].
| Feature | i-gel | LMA Fastrach® (ILMA) |
|---|---|---|
| Primary Function | Ventilation and intubation conduit [1.8.4] | Primarily an intubation conduit [1.5.1] |
| Blind Intubation Success | Generally lower overall success rate (approx. 73-82%) compared to LMA Fastrach [1.4.4, 1.2.3]. | Higher overall success rate (approx. 90-96%) [1.4.1, 1.2.3]. |
| Fiberoptic View | Provides a better view of the glottic opening [1.5.1]. | View can be less optimal compared to i-gel [1.5.1]. |
| Insertion Speed | Faster insertion due to no cuff inflation [1.5.3, 1.8.6]. | Slower insertion due to its rigid structure and cuff inflation [1.5.3]. |
| Design | Soft, non-inflatable cuff mirroring anatomy [1.5.3]. | Rigid, curved shaft with an inflatable cuff and guiding ramp [1.2.3]. |
| Complication Rate | Lower rates of sore throat and trauma compared to some LMA models [1.8.6, 1.5.6]. | Higher rates of sore throat reported in some studies [1.8.6]. |
While the LMA Fastrach® is superior for blind intubation, the i-gel offers advantages such as faster insertion, better fiberoptic view, and lower complication rates, making it a preferable conduit for fiberoptic-guided intubation [1.5.3, 1.5.6]. The newer i-gel® Plus model includes features like a ramp in the airway tube specifically to optimize the direction for intubation [1.6.6].
Complications
While generally safe, intubation through an i-gel is not without potential complications. These are similar to those associated with other SADs and include:
- Airway Trauma: Minor trauma, indicated by blood on the device upon removal, can occur in 4-13% of cases [1.7.2].
- Sore Throat: The incidence is generally lower with the i-gel compared to cuffed devices [1.8.6].
- Nerve Injury: Rare cases of lingual or mental nerve injury have been reported [1.7.2].
- Laryngospasm: Can occur, with an incidence of around 1.2% in large studies [1.8.1].
- Failed Intubation/Esophageal Placement: A significant risk, especially with the blind technique [1.8.1].
Conclusion
Yes, you can intubate down an i-gel, and it is frequently used as a conduit for endotracheal intubation, especially in difficult airway algorithms [1.2.1, 1.8.3]. For blind intubation, a standard PVC endotracheal tube appears to offer the highest success rate, though this method is less reliable than using an LMA Fastrach® [1.2.1, 1.5.3]. The i-gel excels as a conduit for fiberoptic-guided intubation, where its design often provides a superior view of the vocal cords, leading to high success rates and faster procedures compared to other devices [1.5.1, 1.5.6]. Its ease of insertion and lower postoperative morbidity make it a valuable and versatile tool in modern airway management. For more information, you can consult resources from the Difficult Airway Society.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Airway management procedures should only be performed by trained and qualified medical professionals.
