The purpose of this study is to evaluate a new disposable supra-glottic airway device, the
i-gel airway (Intersurgical Ltd., Wokingham, England). We propose to test its ease of
insertion, position within the airway, drain tube patency and anatomic sealing properties
during mechanical ventilation in non-obese anesthetized patients undergoing elective general
surgery. The study device will be compared to the current standard in the industry, the LMA
During the past decade, several pharyngeal airways have been introduced for airway
management, such as the Laryngeal Mask Airway (LMA), the Cobra perilaryngeal airway, the
Esophageal Tracheal Combitube (ETC), the EasyTube, the Laryngeal Tube6, and the Streamlined
Liner of the Pharyngeal Airway (SLIPA). These airway devices have become very popular
because of their ability to maintain an airway without perturbing the trachea and can be
used in patients without muscle relaxation who are only lightly anesthetized.
The LMA Classic (cLMA) generally provides an adequate airway, but certain problems remain:
1. In 8-33% of LMA placements, more than one attempt is required.
2. It is sometimes difficult to advance the LMA without extending the neck (which is
contraindicated in some patients).
3. The device does not protect the airway from aspiration of gastric contents.
4. It does not provide an airtight seal around the larynx (the usual pressures causing
leakage of gas being 15-20 cm H20). Consequently, the device may function poorly
during positive-pressure ventilation.
5. The esophagus is included within the rim of the LMA in 10-15% of patients, directly
exposing the esophagus to positive airway pressures. This often results in insufflation
of the stomach and postoperative discomfort.
The LMA Unique (uLMA) is a disposable, inflatable supraglottic airway device that is based
on the LMA Classic design which has been used as the "model" in the industry. It has been
listed as a commonly accepted device for routine and rescue airway management and is now
listed in the American Society of Anesthesiologists (ASA) Difficult Airway Management
Algorithm as an airway conduit for tracheal intubation.
The i-gel (Intersurgical Ltd., Wokingham, England) is a cuffless, single-use supraglottic
airway device designed to provide a more effective seal than the uLMA, thus eliminating
problems 3-5 described above with the addition of a gastric drain. Made of a gel-like
thermoplastic elastomer, the i-gel has an anatomically-designed mask that allows quick, easy
insertion and can accurately position itself over the laryngeal framework to provide a
reliable perilaryngeal seal without the need for an inflatable cuff. In a preliminary
study, the peak airway pressures were found to be above 30 cm H2O with a sustained leak
pressure of 24 cm H2O versus an average of 18-21 cm H2O seen with the cLMA. According to the
100 patient trial, the i-gel is easier to insert, it has better sealing properties and there
is no cuffed inflates.
This clinical study has been designed to compare the i-gel and the uLMA, as to ease of
placement, ventilation during mechanical ventilation, proper positioning, seal pressures,
the patency of the drain tube, and finally, any complications with their use. Fiberoptic
observations through each device will provide information in relation to the epiglottis and
the distal opening of the device.
1. The subjects will be adult surgical candidates aged 18-80, ASA I-II, Mallampati I or
II, presenting for elective surgery who require general anesthesia in whom tracheal
intubation is not necessary.
2. Both male and female patients will be included.
Patients will be excluded from the study if they present as Mallampati III or IV, ASA
III-V or emergency status. Additionally, they will be excluded if they meet one of the
contraindication criteria of the LMA including:
1. obesity, (BMI > 35 kg/m2)
3. history of gastric regurgitation, heart burn, ileus or "full stomach"
4. history of low pulmonary compliance or high pulmonary resistance
5. known history of difficult endotracheal intubation or signs suggesting the
possibility of difficult intubation
6. pharyngeal pathology
7. upper airway obstruction due to laryngeal pathology