12.4.1 What Is the LMA Fastrach™, or Intubating LMA, and Why Was It Developed?
While it is possible to intubate the trachea through an LMA, success rates are variable. Accordingly, an Intubating LMA (LMA Fastrach™, or Intubating LMA (ILMA), LMA North America Inc., San Diego, CA [Figure 12-2]) was designed by Dr Brain. The device has a rigid metal-curved airway tube with a guiding handle, an epiglottis-elevating bar, a deeper bowl, and ramp that directs an ETT up and into the larynx. The device is easy to use, is associated with high success rates of intubation, and has received widespread acceptance. The ILMA is a reusable device which can be cleaned and sterilized using an autoclave. A disposable device has also been recently introduced.
12.4.2 How Is Tracheal Intubation Performed Using the ILMA?
Tracheal intubation through the ILMA can be achieved blindly. To facilitate the insertion of an ETT through the ILMA, the following steps are recommended:
Lubricate the posterior side of the ILMA and the ETT (including the connector of the tracheal tube) with a water-soluble lubricant. Ensure that the ETT slides easily through the ILMA.
With the patient in a sniffing position, open the airway by using a head tilt. It should be emphasized that the insertion of an ILMA may be difficult if the interincisor gap is less than 20 mm.
Grasp the metal handle of the ILMA and insert the device straight back over the tongue to the back of the oropharynx. Then advance the cuff into the hypopharynx following the palatopharyngeal curve by rotating the device using the metal handle and maintaining gentle pressure against the palate. Once in place, inflate the cuff to achieve a seal for manual ventilation. The metal handle may be used to manipulate the device to achieve a seal to ensure adequate ventilation and oxygenation. The device should be gently rotated in the sagittal plane (commonly known as the first Chandy maneuver) to establish optimally unobstructed ventilation.43
While a number of ETTs, including the Mallinckrodt Hi-Lo PVC tube, can be used for tracheal intubation, the dedicated wire-reinforced silicone-tipped tracheal tube (TT) supplied with the ILMA has been shown to give the highest success rates.44 With the black vertical line on the tube facing the operator, insert the tube into the metal lumen of the ILMA until the horizontal black line on the tracheal tube meets the proximal end of the ILMA metal tube (Figure 12-2). At this point, the tip of the TT is just emerging from beneath the epiglottis-elevating bar. Resistance will be felt as the TT elevates this bar exiting the distal end of the ILMA, and entering the patient's glottis.
Tracheal placement is confirmed in the usual manner. Manipulation of the ILMA by lifting the device from the posterior pharyngeal wall using the metal handle (the second Chandy maneuver) may enhance successful passage in the event of failure. This manuever helps to prevent the TT from colliding with the arytenoids and minimizes the angle between the aperture of the ILMA and the glottis.45
Some evidence suggests that the ILMA in situ produces sufficient pressure on the posterior hypopharyngeal wall to potentially compromise mucosal blood flow.46 For this reason, except perhaps in an airway rescue or resuscitation situation, it is recommended that the device be withdrawn over the TT. A stabilizing rod is provided with the ILMA to hold the TT in position while the ILMA is withdrawn.
Many investigators have studied the effectiveness of the blind intubating technique through the ILMA. The reported mean (range) first-time and overall success rate is 73% (53-100) and 90% (44-100), respectively.46 Several factors that decrease success rates of blind intubation through the ILMA technique have been identified: the use of a #3 ILMA, instead of #4 or #5 ILMA, for adult male patients; the application of cricoid pressure; lifting the ILMA handle; the use of a collar; and an inexperienced practitioner.
12.4.3 What Other Techniques Have Been Described to Enhance Success Rates for Tracheal Intubation through the ILMA?
Several studies have been published evaluating the effectiveness of a laryngoscope to assist ILMA intubation. The overall success rate appears to be no better than the blind technique. Light-guided techniques employing a flexible lightwand (Trachlight™) have also been investigated, and have demonstrated improved success rates.47,48 Lightwand-guided intubation through the ILMA has a first-time and overall success rate of 84% and 99%, respectively.46 Recently, Wong et al49 reported the successful use of the Trachlight-assisted Fastrach intubation in a patient with a difficult airway secondary to the Hallermann-Streiff syndrome. In out-of-hospital tracheal intubation by an emergency physician, Dimitriou et al has shown that a flexible lightwand-guided tracheal intubation through the ILMA had a high success rate, with no failures in 37 patients.50
Pandit et al51 found that bronchoscopic-guided intubation had a higher success rate (95%) through the ILMA than through the LMA (80%), although the time to intubation was longer with the flexible bronchoscope (FB)-assisted technique, compared to the blind technique (74 seconds vs 49 seconds). Overall, in a range of studies, flexible bronchoscope-guided intubation through the ILMA has a first time and overall success rate of 87% and 96%, respectively. However, following a failed blind technique, flexible bronchoscope-guided intubation through the ILMA has a success rate of only 86%.46
Agro et al52 reported the use of a shorter fiberoptic device, Shikani Seeing Eye Stylet™, (Clarus Medical, Minneapolis, MN, USA) to facilitate a Fastrach intubation. Although tracheal intubation was successful, the investigators commented that the major limitation of the Shikani device was its inability to control the direction of the tip of the device.
Using the Patil Intubation Guide (Anesthesia Associates Inc., San Marcos, CA, USA), a whistle diaphragm to detect breath sounds, Osborn successfully intubated the trachea through the ILMA under topical anesthesia in a patient with a recent cervical spine fusion.53 In 2005, a case series was published describing the successful use of the airway whistle with the ILMA in four patients with known difficult airways.54
12.4.4 What Are the Indications for the ILMA?
The ILMA alone does not prevent the aspiration of gastric contents and may produce hypopharyngeal mucosal ischemia if it is left in place for a prolonged duration. Therefore, its role in routine airway management may be limited. However, when used as a temporizing measure, it is a highly effective device in the emergency environment, as an adjunct to failed or difficult BMV, and as a rescue device in the failed airway. Brain has suggested that the ILMA may not be indicated when the patient is anticipated to be an easy intubation (easy direct laryngoscopy), but may be of considerable benefit when the glottis is high and anterior (difficult direct laryngoscopy). Furthermore, recent studies have confirmed earlier findings that ventilation and intubation through the LMA Fastrach™ can be successfully achieved in obese patients with BMI greater than 30.55,56
With respect to emergency medical services (EMS) and prehospital care, the importance of early and effective airway control is universally acknowledged. Tracheal intubation under direct laryngoscopy is associated with a number of practical problems in prehospital trauma and there is evidence to suggest that the ILMA may play an important role in the prehospital setting, in securing the airway of trauma patients with a head injury.57,58
In a recent study by Gercek et al,59 the degree of cervical spine movement of three common methods of tracheal intubation in patients with C-spine injuries (direct laryngoscopy [DL], ILMA, and FB) were compared using real-time, three-dimensional ultra-sonography in healthy elective surgical patients with manual in-line immobilization. They showed that manual in-line immobilization reduced the cervical spine range of motion during different intubation procedures to a limited extent: the least diminution (ie, the greatest C-spine movement) occurred with DL (with an overall flexion/extension range of 17.57 degrees), versus significantly less c-spine movement with ILMA use (overall flexion/extension range of 4.60 degrees), and FB use (overall flexion/extension range of 3.61 degrees—oral, 5.88 degrees—nasal). Furthermore, the mean (± SD) total time required for intubation was shortest for the ILMA (16.5 ± 9.76 seconds), followed by DL (27.25 ± 8.56 seconds), and the longest for both FB techniques (oral: 52.91 ± 56.27 seconds, nasal: 82.32 ± 54.06 seconds).
The prime role of the ILMA lies in managing the airway of patients with a difficult or a failed airway. From a retrospective study involving 254 patients with difficult airways, including patients with either Cormack/Lehane Grade 4 views, immobilized cervical spines, stereotactic frames, or airways distorted by surgery or radiation therapy, the clinical experience with the ILMA (both elective and emergency use) has been largely positive.45,60
The Difficult Airway Society (UK) guidelines for management of the unanticipated difficult tracheal intubation in the nonobstetric adult patient without upper airway obstruction now include the ILMA.61
The LMA C-trach™ was a modification of the ILMA (Fastrach™) fitted with a fiberoptic camera to allow continuous visualization of the airway. When compared to the ILMA, it was shown to have a higher first attempt success rate, but a longer insertion time.62 This device is no longer available on the market, largely due to its cost.