Airway management is a basic and essential skill of anyone caring for an injured or a seriously ill patient. Although many patients can be managed with a non-invasive airway, many benefit from endotracheal intubation.
Much has been written about the hazards of endotracheal intubation, even in this latter patient group. Paralytics have been suggested, and utilized, by some ground and air EMS systems, but concern has arisen over the ability of crews to achieve effective intubation even with paralytics.
One study, for example, showed esophageal intubation rates for all patients as high as 25%.1 The challenge for prehospital advanced life support (ALS) providers, then, is achieving a balance between the need for intubation and safely achieving that intubation.
Even in the most controlled circumstances, endotracheal intubation can be challenging. Although the addition of routine end-tidal CO2 (EtCO2) monitoring has reduced the incidence of esophageal intubation, it does not reduce the difficulty of the prehospital intubation process. In the field, poor lighting conditions, bad weather, the physical location of the patient, injuries to the neck and spine, and variations in skill levels of the operators contribute to that difficulty. But new technology may be able to provide some, if not all, of the solution to that dichotomy.2
The goal of any new airway technology should be to reduce multiple attempts at intubation, as well as prevent dental, mouth and airway trauma, desaturation, intracranial hypertension, pneumothorax, pulmonary aspiration and even iatrogenic death from an unrecognized esophageal placement.2
The Advent of Video Laryngoscopy
For many years, direct laryngoscopy (DL) has been the gold standard by which to achieve intubation, performed with either curved or straight laryngoscope blades. However, DL often yields surprisingly poor laryngeal views. Alternatives have been explored, but most have proved to be difficult to master, time consuming, unreliable and costly. Even rigid fiber-optic laryngoscopes—the technology on which “modern” DL is based—hasn’t been widely used, despite its advantages. What has been needed is a device that provides a full view of the glottic airway during laryngoscopy and is easy to learn and master by medical personnel who may or may not frequently perform intubations.
A significant advance took place in this realm when the video laryngoscope (VL) was developed for use in the surgical suite. These devices have a camera lens incorporated into the handle or blade, allowing the image of the larynx/
glottis to be displayed on a monitor that’s either directly attached to, or separate from, the blade/camera system. The ability to see the larynx while intubating, even in the most difficult patients, as well as being able to use the monitor as a teaching tool, are recognized as important advancements in airway management.
Although many of these devices (i.e., McGrath Series 5 from LMA North America, TruView from Truphatek, Storz DCI, AWS-S100 from PENTAX Medical Co., Video Macintosh Intubating Laryngoscope System from Volpi AG and GlideScope® from Verathon Medical®) have proved their worth in the hospital setting, a new design was necessary for use in the prehospital environment. This new device would have to be rugged, small and easy to manipulate when working in difficult field conditions.
Currently, the only product on the market that we believe meets all of the criteria for
use in the prehospital environment is the compact GlideScope Ranger.
The Ranger has a digital camera lens incorporated into the center (versus the tip) of its specialized blade, which allows a wider view of the vocal cords on its monitor. A unique anti-fogging technology provides an unobstructed view of the larynx throughout the entire process of tube placement, a feature that’s especially valuable during emergency intubation. It weighs less than 2 lbs. and is engineered to be dependable in a variety of challenging field conditions, including very high or low temperatures, high humidity, and high altitude.
The Ranger is powered by a rechargeable lithium battery, which provides a minimum of 90 minutes of continuous use. A rigid stylet aids in the control of the endotracheal tube (ETT) as it enters the larynx. The blade has a 60º curvature in the midline to match anatomical alignment, so it doesn’t require a “line of sight” for a good view. The high-resolution color display monitor provides a clear picture of the larynx and vocal cords even in bright light, which, again, transforms it into a valuable teaching tool.
There appear to be special benefits to the GlideScope Ranger for trauma patients with limited mouth opening or in cervical immobilization.3 Very little force is required to expose the glottic opening with the blade so manipulation of the head and neck is reduced. It also functions well in situations where blood or other fluids are present, in mildly obese patients, and because direct visualization of the glottis is unnecessary during intubation, the GlideScope Ranger is less stimulating, an advantage for use in semi-awake patients.
A New Technique
The manner in which tracheal intubation is performed with the GlideScope is unique to its design. The handle is held in the left hand in the same way that one would hold a standard laryngoscope, while the blade is inserted between the teeth under direct vision. It’s important to start out in the midline of the tongue and to stay on the midline. (There’s no need to sweep the tongue out of the way, as is usually the practice with conventional laryngoscopes.)
When the uniquely curved blade passes the teeth, the clinician can now follow the landmarks on the video monitor proceed to the larynx. Identifying the glottis is generally easy. The only technical difficulty with the GlideScope may be guiding the ETT toward the image of the glottis seen on the screen. This difficulty is encountered because the camera is directed (by design) at a 60º angle.
The manufacturer recommends bending the ET tube to conform to the shape of the blade for a gentle curve of 60º. Still, the angle by which one inserts the tube is quite steep. A special stylet developed to lessen the difficulty of passing the tube into the trachea is available, but if advancing the tube presents a problem, withdrawing the GlideScope 1–2 cm will allow the larynx to drop down and reduce the angle required to insert it correctly.
The main limitation of the GlideScope is that there may be a physical resistance in the advancement of the ET tube; with a little practice this limitation is easily overcome. But once familiar with the steep angle of approach, the device is extremely easy to handle.
The following are examples from Whatcom (Wash.) Medic One of the type of cases in which the GlideScope Ranger may be extremely useful.
Case 1: EMS responded to a conscious 57-year-old female, a victim of a fire that started in her home. She had second-degree burns on her legs, buttocks and thighs greater than 30% of her body. She had redness of her face, but no obvious singeing of nares. There were questionable particulates in her oral cavity, but no voice change. Pulse oximetry was 93% on room air, rising to 95% on oxygen given by non-rebreather (NRB) mask. The patient had a history of smoking one pack per day. Respiratory rate was 30 but appeared unlabored. Blood pressure was 130/90, heart rate was 110. She was awake and talking.
Because she was 25 miles from a community hospital and 100 miles from a burn center, and although a major airway burn was not expected, it was elected to provide rapid sequence intubation (RSI) as a precaution prior to helicopter transport to the burn center. RSI was conducted, and the GlideScope Ranger was used to visualize the airway.
Surprisingly, the crew found she had soot in her pyriform sinuses, edema of her glottic opening and significant erythema of the entire region. The GlideScope made possible a quick (18 seconds) and easy intubation, and the video monitor provided an excellent teaching opportunity the prehospital personnel involved. In addition to direct visualization, EtCO2 further confirmed correct tube placement.
Case 2: EMS responded to a 60-year-old male in severe respiratory distress. He was in the bedroom of a manufactured home. He suffered from severe Pickwickian syndrome related to morbid obesity, and had a body mass index (BMI) of 43. (His weight was approximately 656 lbs).
He was obtundent and had a pulse ox of 85%. Blood pressure could not be obtained in the patient’s current position, and moving the patient would require assistance that was not available at the time. His respiratory rate was 40, shallow and labored. Oxygen by NRB mask did not improve his condition.
In light of further deterioration, intubation was the only alternative. However, his BMI and body habitus were going to make it a difficult intubation. He was sedated with midazolam and, using the Ranger, was intubated within 26 seconds. Despite limited mouth opening and a difficult position, tube passage was assured via excellent visualization of his vocal chords.
Case 3: EMS responded to a 67-year-old male in cardiac arrest found in an alley behind a tavern. It was 2 a.m. and raining, and he was difficult to get to because vehicle access was blocked by construction in the area. The first responding basic life support (BLS) unit started CPR with bag-mask ventilation (BMV) performed with extreme difficulty.
The patient had vomited copious amounts of stomach contents. The AED showed that no shock was indicated. After suctioning the oral cavity, intubation was performed with the Ranger in 33 seconds. Tube placement was confirmed by direct visualization on the GlideScope monitor and EtCO2. The patient, who had probably sustained a primary respiratory arrest, was successfully resuscitated.
Case 4: EMS responded to a car struck by a semitruck at high speed. The driver of the car was trapped in the vehicle and had significant craniofacial trauma. His airway was compromised, and he had agonal respiration. To extricate him, extensive rescue operations were required.
A paramedic was able to intubate the patient from the open windshield using a Ranger with the blade of the laryngoscope reversed. It took two attempts and 42 seconds to place the tube, with suctioning required after the first attempt. Confirmation of tube placement was done via direct visualization on the GlideScope monitor and EtCO2.
These case reports demonstrate the capabilities of a video laryngoscope, now available to EMS personnel, in performing emergency intubation. In the first case, without video visualization it would have been difficult to diagnose the glottic swelling that was unsuspected on initial examination. In the second case, this high-BMI patient with complex anatomy might not have been able to have any airway achieved. In the third, a dark night, aspiration and other factors made any airway extremely difficult. And in the fourth, it’s unlikely the intubation could have taken place at all until the patient was extricated from the vehicle.
The ability to successfully intubate critical patients in the field, especially those who present with difficult airways for a variety of reasons, is an important advancement in emergency airway management.
The Impact on Prehospital care
The potential impact of video laryngoscopy on prehospital medicine may be significant, especially for ground services that are often faced with difficult airways and air medical personnel who must work in tight quarters while airborne.
As previously mentioned, field intubations are by definition fraught with potential complications, such as esophageal intubation, pneumothorax, reduced ventilation and oxygenation, and pulmonary aspiration.2 Because of the ability to visualize the airway without distortion from fogging to, in effect, “see around the corner,” many of these complications can be avoided.
One study looked at Cormack-Lehane ratings (Grades 1–1V) of those obtained with the GlideScope in 15 patients with cervical collars.4 The Cormack grading in 14 of the 15 patients (93%) was reduced by one when using the GlideScope. Five Grade I1 patients became Grade 1 using the GlideScope. The average time of intubation with the GlideScope was 38 seconds without complications, including any damage to the teeth. This improvement in visualization of the glottis during intubation is a major factor in the conclusion of some that direct laryngoscopy for emergency intubation will become a relic.2,3
The GlideScope has also become the method of choice for many in training of airway management.5 Currently, Whatcom Medic One is conducting a crossover study of video camera-assisted intubation versus traditional laryngoscopy. Although preliminary data is encouraging, many questions remain to be answered. These include cost versus benefit and skill maintenance of the traditional technique when a camera system isn’t available. Time and the marketplace, we believe, will help answer those questions. However, a new era of airway management may soon be on all of our horizons.
Disclosure: The author has received no monetary support from Verathon Inc. His EMS system, Bellingham/Whatcom County, Wash., has received support from Verathon in the form of four video laryngoscopes for evaluation and research purposes.