Intubating Laryngeal Mask— An Alternative to the Laryngeal Mask Airway?
ABSTRACT & COMMENTARY
Source: Baskett PJF, et al. The intubating laryngeal mask: Results of a multicenter trial with experience of 500 cases. Anaesthesia 1998;53:1174-1179.
This study investigated the use of a device, the intubating laryngeal mask (ILM), designed to assist in the management of the patient with a difficult airway. The aims of the study were to assess the ease of insertion and lung ventilation through the ILM, assess the ease of intubation using a flexible endotracheal tube passed blindly through the ILM, determine the learning curve of the acquisition of these skills, and assess the hemodynamic response both to the insertion of the ILM and to the passage of the tracheal tube through the device. The setting was the operating room and the investigators were anesthesiologists.
In 89% of cases, the insertion was described as easy. Ventilation using just the ILM was described as adequate in 95% of cases. Blind tracheal intubation through the ILM was achieved on the first attempt in 80% of the patients. Intubation in three attempts could not be accomplished in 19 of the 500 patients. Seventeen of the 19 failures occurred within the investigators’ first 20 attempts during the course of the study. Hemodynamic responses to the insertion of the device, as well as blind intubation through the device, were unremarkable. Baskett and colleagues concluded that the ILM is a viable and perhaps superior alternative to the laryngeal mask airway (LMA) in patients who present with a difficult airway problem.
Comment by Glenn C. Freas, MD, JD, FACEP
Inability to perform endotracheal intubation is one of the most difficult challenges we face. When the emergency physician has difficulty with direct laryngoscopy and endotracheal intubation, there are a variety of techniques and tools that have been described to assist in securing an airway, including: digital intubation, retrograde intubation using cricothyroid puncture and a guidewire, fiber-optically guided intubation LMA, and cricothyroidotomy.
Baskett et al compare the efficacy of the ILM with that of the LMA and none of the other techniques listed above. The technique that they describe for using the ILM is best used in combination with specially designed endotracheal tubes, which are straight, semirigid, and beveled differently than the standard tube. They assert that the LMA is too long and narrow to act as an acceptable guide for intubation in every case, and that it is not easy to remove the LMA once intubation has been accomplished. When the proper size ILM is used in combination with the specially designed endotracheal tubes, in experienced hands, the ILM may be superior to the LMA—given these data presented by Baskett et al. Caution should be used when extrapolating these data for use in our practice. The study was performed in the relatively ideal conditions of elective surgery in the OR. Patients with difficult airways were not the subject of the study. The investigators received special training in their technique and clearly demonstrated a learning curve requiring 20 or more attempts. Nonetheless, it would be foolish for emergency physicians to not consider adding this device to our repertoire for establishing an airway in difficult circumstances. Whether it favorably compares to other devices and techniques previously described will likely be a matter of personal preference.
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