Air-Q® SP Versus Air-Q® and I-gel: A Randomized Clinical Trial

Not Applicable

Completed

Conditions: Laryngeal Masks

Interventions: Device: air-Q
Device: i-gel
Device: air-Q SP

Registration Number: NCT01592760

Lead Sponsor: University of Wisconsin, Madison

Brief Summary: The air-Q Self-Pressurizing Intubating Laryngeal Airway (aILA SP) is a modification of the air-Q Intubating Laryngeal Airway (aILA). Besides the i-gel, it is the only breathing tube that sits above the vocal cords that does not require inflation of a cuff with air. The purpose of this study is to compare the ability of the aILA-SP to maintain patency of a patient's airway during general anesthesia with that of the aILA and i-gel devices. As a measure of this ability, we hypothesized that the airway sealing pressures will be equal between the aILA-SP and aILA, but superior when comparing the aILA-SP to the i-gel (i-gel will be lower).

Detailed Description: Laryngeal mask airways (LMAs) are a group of airway devices, alternatively referred to as supraglottic airways (SGAs), used in anesthesia that are positioned in the back of the throat (pharynx) above (supra) the glottis (windpipe opening) and the vocal cords. This is in contradistinction to a tracheal tube, which is an airway device that is placed through the vocal cords and extends to a position below the glottis (infraglottic) and resides in the trachea (windpipe). Since their first approval for use in the United States by the US Food and Drug Administration in the early 1990s, the application of SGAs has become more widespread. Initially, they were only used in anesthetized patients who were breathing on their own (i.e., spontaneously ventilating). This was, in large part, due to a relatively low airway seal pressure, the pressure with which the device seals against the throat, thereby, keeping the air pushed in by a breathing machine (ventilator) from getting into the stomach or leaking out around the device and out through the mouth - in either case, not going into the patient's lungs. The relatively low airway seal pressure (18 - 20 cmH2O) did not allow for the use of muscle relaxant (paralyzing) drugs and positive pressure ventilation. Successive generations of SGAs by a variety of manufacturers have overcome and continue to attempt to overcome limitations of earlier devices. In addition, accumulated clinical experience has made anesthesia providers more comfortable with their use. No SGA, however, is yet ideal, and incremental changes continue to appear to improve airway management and reduce airway morbidity (e.g., sore throat, jaw pain, etc.).

The air-Q® Intubating Laryngeal Airway (aILA, Mercury Medical, Clearwater, FL) is a newer, commercially-available, SGA designed for use as a primary airway and as an intubation conduit. It is available in polyvinyl chloride (PVC)-based, single use and silicone-based, reusable models. Information on its safety and effectiveness from a randomized, controlled trial in adults, undergoing general anesthesia, compared to that of the silicone-based, reusable aILA versus the LMA-Proseal™ (pLMA, North America, San Diego, CA), the current "gold standard" for SGA airway seal pressure, is available.

The air-Q® Self-Pressurizing (SP) Intubating Laryngeal Airway (aILA-SP, Mercury Medical, Clearwater, FL) is a commercially-available, modification of the silicone-based, reusable aILA. Its overall design is identical to the aILA, but incorporates a communication orifice between the air tube and cuff, which regulates airflow into and from the cuff during periods of positive pressure and spontaneous ventilation. As such, it incorporates a self-pressurizing cuff that does not require manual inflation. Such a cuff may be advantageous insofar as it dynamically adjusts its intra-cuff pressure and fit with the patient's pharyngeal and periglottic anatomy, which may lead to a reduction in airway morbidity, while still providing the high seal pressure afforded by the aILA design.

Lastly, the i-gel (Intersurgical Inc., Liverpool, NY) is a commercially-available SGA that uses a thermoplastic elastomer to create a non-inflating, anatomically-conforming, periglottic cuff. Studies have shown it to be an easily inserted, effective airway device with a lower incidence of sore throat and neck complaints. With exception to the aILA-SP, it is the only other commercially-available SGA that does not require cuff inflation.

To date, no reports are available on the clinical performance of the aILA-SP in relation to other SGAs. Thus, the primary purpose of this study is to compare the airway seal pressure (ASP) of the aILA-SP against the aILA and i-gel in adults undergoing general anesthesia. Airway seal pressure is the most common surrogate for ventilatory capacity used in SGA studies.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 225

Inclusion Criteria

≥ 18 years;
scheduled for an elective surgery or procedure; and
general anesthesia with placement of a SGA planned.

Exclusion Criteria

< 18 years of age;
non-English speaking;
known or believed to be pregnant;
prisoner;
has impaired decision-making capacity;
has symptomatic untreated gastroesophageal reflux;
has had a prior esophagectomy;
has a known or suspected hiatal hernia;
has vomited within twenty-four hours of the surgery or procedure;
has known oral pathology making a proper SGA fit unlikely; or
has any condition for which the primary anesthesia care team deems intubation with a tracheal tube to be necessary.

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
air-Q	air-Q	air-Q Intubating Laryngeal Airway, sizes 3.5 and 4.5 (Mercury Medical, Clearwater, FL, USA)
i-gel	i-gel	i-gel, sizes 3, 4, and 5 (Intersurgical Inc., Liverpool, NY, USA)
air-Q SP	air-Q SP	air-Q Self-Pressurizing Intubating Laryngeal Airway, sizes 3.5 and 4.5 (Mercury Medical, Clearwater, FL, USA)

Primary Outcome Measures

Name	Time	Method
Airway Seal Pressure After Device Placement	Measured within 5 minutes after device placement/study initiation	Airway seal pressure is defined as the pressure in cmH2O at which the needle of a manometer attached to the anesthesia circuit reaches equilibration, associated with an audible air leak from the subject's oropharynx or gastric insufflation, limited to a maximum pressure of 40 cmH2O. It is measured with the subject's head and neck in neutral position, the expiratory valve on the anesthesia machine closed, and the fresh gas flow set to five liters per minute.

Secondary Outcome Measures

Name	Time	Method
Device Position in Relation to the Vocal Cords	Measured within 5 minutes of successful study device placement	Device position in relation to the vocal cords is assessed with a flexible fiberoptic camera and graded as follows: 1 = full view of the vocal cords, 2 = partial view of the vocal cords including the arytenoids, 3 = view of the epiglottis only, and 4 = other (device cuff, pharynx or other structures).
Overall Clinical Usefulness	Reported by the device operator at the time of device removal	Excellent, good, fair, or inadequate. Scale defined by clinical measures and observations.
Device Use Time (Min)	Measured between successful device placement and device removal for any reason, approximately 2 hours	Device Use Time is the time recorded to the nearest minute of the period bounded by the time the device placement was determined to be adequate in the study subject to its withdrawal from the study subject.
Incidence of Gastric Aspiration	Measured between successful device placement and device removal for any reason.	Gastric aspiration is present when gross gastric contents or bile is observed on or within the device or within the subject's oropharynx. The outcome is the proportion of study subjects in whom the outcome measure was observed.
Device Placement Time	Measured at device placement/study initiation	Device placement time is the time measured in seconds from when the study investigator picks up the airway device to confirmation of ventilation by the presence of an adequate end-tidal carbon dioxide tracing on the monitor.
Device Ease of Insertion	Reported by the device operator at the time successful device placement is recorded.	Device ease of insertion is graded as either easy, slightly difficult, difficult, or impossible. The outcome measure is the proportion of successful study device placements recorded as easy versus slightly difficult versus difficult versus impossible.
Device Placement Success Rate	Measured at the time of attempted study device placement immediately after the induction of general anesthesia	Device placement success rate is defined as the proportion of devices successfully placed within three attempts at device placement.
Incidence of Gastric Insufflation	Measured within 5 minutes of device placement/study initiation	Gastric insufflation is present when audible air sounds are heard by stethoscope over the subject's epigastrium.
Oropharyngolaryngeal Morbidity at Discharge	Measured prior to discharge from phase II of the post-anesthesia care unit/recovery room	Perioperative oropharyngolaryngeal morbidity is assessed by the subject's response to standardized questions regarding oropharyngeal complaints.
Incidence of Oropharyngeal Injury	Measured in the post-anesthesia care unit/recovery room within 15 minutes after device removal	Oropharyngeal injury is defined as a new lip, tongue, buccal, or pharyngeal abrasion or laceration or dental damage observed in the immediate recovery area after use of a study device.
Oropharyngolaryngeal Morbidity at 24 Hours Post-operatively	Measured at 24 hours after device placement/study initiation	Perioperative oropharyngolaryngeal morbidity is assessed by the subject's response to standardized questions regarding oropharyngeal complaints.