John C. Sakles
Calvin A. Brown III
Introduction
When tracheal intubation was invented more than 100 years ago, it was performed blindly using the fingers to palpate the laryngeal inlet and guide the tube into the trachea. Shortly thereafter, laryngoscopes were invented, allowing for direct visualization of the larynx. These laryngoscopes were essentially metal spatulas with a light bulb on the tip. The blade lifted the tongue out of the way, and the light bulb illuminated the glottic structures. The straight blade, or Miller blade, was introduced by Robert Miller in 1941, and 2 years later, Sir Macintosh introduced the curved or Mac blade. Interestingly, little has changed, and modern-day intubations are still largely performed with Miller and Mac blades. There have been minor developments in laryngoscopes throughout the years, but their core design remains unaltered. Over the past few years, the most significant change in the field of intubation is video laryngoscopy. This technology involves placement of a micro-video camera on the laryngoscope blade to transmit glottic images to an external monitor, allowing the operator to perform tracheal intubation while watching the video screen instead of looking directly through the mouth. Video laryngoscopy has several important advantages over traditional direct laryngoscopy. First, video laryngoscopy magnifies the view of the airway and allows the operator to see the airway in greater detail, thereby increasing the chance of successful intubation. Second, the anterior angulation of the blade and placement of the video camera allow the operator to see structures that would be difficult or impossible to see under direct vision. Furthermore, video laryngoscopy can enhance education by allowing other health care providers to visualize the anatomy the operator is viewing. The use of the video laryngoscope also makes it possible to record the procedure to provide an excellent teaching resource and documentation for the medical record. There have been several video laryngoscopes introduced over the past few years. This chapter reviews the most important video laryngoscopes currently available on the market.
Devices
GlideScope Video Laryngoscope
Device Components
GlideScope System
The GlideScope Video Laryngoscope (GVL) consists of a video laryngoscope with a micro-video camera encased within a modified MacIntosh blade, a rechargeable 7-in. video liquid crystal display (LCD) monitor, and a video cable that transmits the image between the two. There are three system configurations for the GVL system and two mounting options. The monitor can be mounted on a five-legged mobile stand or attached to an intravenous line pole with a C-clamp. The third configuration is to purchase the GVL within a hard shell case with foam compartments housing the monitor, cable, and room for all three blades (Fig. 14-1A). This configuration is ideal for mobile or remote field emergency applications.
The laryngoscope portion of the GVL consists of a combined handle and laryngoscope blade that are made from durable medical-grade plastic. The video camera is placed in a recess midway along the undersurface of the laryngoscope blade, protecting it from contamination from bodily secretions. In addition, the GVL incorporates an antifog mechanism that heats the lens around the video camera, thereby eliminating fogging during laryngoscopy. There are three blade sizes for the GVL: large, midsize, and small. The large blade corresponds to an adult size blade and can be used for most adults, including those who are morbidly obese. The medium-size blade is similar to a pediatric blade and can be used to intubate toddlers up to small adults. The small blade is considered a neonatal blade and is for use in newborns to toddlers 1 or 2 years of age. Because the GVL does not incorporate an endotracheal tube (ETT) guide or stylet connected to the device, ETTs of any size can be used.
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Figure 14-1 • A: The GlideScope Video Laryngoscope system in the hard shell case configuration. The battery-operated monitor is held securely in place with the foam protective insert. Three blades are present in the set: large, midsize, and small. B: The GlideScope Ranger with its protective neoprene case. The cord wraps around the device, and the blade locks in place on the left-hand side. The blade and cord detach from the monitor and can be sent for sterilization. The “working light” on the handle is helpful when using the device in low light conditions such as in the prehospital setting. |
The laryngoscope attaches to a 7-in. LCD monitor via a video cable that also carries power to two light-emitting diodes (LEDs) mounted alongside the video camera to provide illumination. The monitor has a video-out port that requires a proprietary cable to connect to the RCA video input, allowing the image to be transmitted to another monitor or recording device. The monitor can be rotated to the optimal viewing angle, and the cradle rests on a mobile telescoping pole that allows easy adjustment of the height of the monitor. The unit is powered by standard alternating current (AC) or backup rechargeable lithium battery. The battery can provide 90 minutes of continuous use and has a low battery indicator light to warn the operator that the unit must be plugged in.
The GVL's solid design makes it well suited for emergent use in suboptimal conditions where the device is likely to be handled roughly.
GlideScope Cobalt
The GlideScope Cobalt is a disposable one-time use version of the original design. The Cobalt consists of a flexible video baton housing the micro-video camera that inserts into a disposable clear plastic blade, called the Stat, which serves to protect the video system. The Cobalt connects to the same color video LCD monitor as the original GlideScope, and is used in identical fashion as the original GlideScope. Currently, there are two blade sizes available, a large blade for adult patients and a small blade for small adult and pediatric patients. The Cobalt blade is angled slightly more anterior than the original design. The Cobalt can be used with the standard GlideScope video monitor; however, it cannot be used with the portable Ranger unit. The primary advantage of the Cobalt is its single-use design—eliminating the logistical problems, costs, and downtime associated with sterilization of the traditional GlideScope.
GlideScope Ranger
The GlideScope Ranger is a rugged, portable, battery-operated GlideScope unit designed for field use (Fig. 14-1B). It uses a transreflective (TFT) 3.5-inch screen, allowing the operator to see the airway anatomy even while viewing the monitor outdoors in bright sunlight. The Ranger's blade, although somewhat smaller than the original blade, has been designed with a 60-degree viewing angle suitable for visualizing anterior airways. It also incorporates a similar antifogging system to maintain a clear view of the airway at all times. The video camera is positioned approximately halfway along the blade to protect the lens from contamination, including secretions, blood, and vomitus. The rechargeable lithium polymer battery provides 90 minutes of use. The GlideScope Ranger is contained within a soft-sided case with belt attachments for ease of use and mobility. The manufacturer recently has developed the Cobalt Ranger, which will incorporate the Cobalt design within the Ranger system. Two blade sizes are available for the Cobalt Ranger, a small blade and a large blade.
Use of Device
The GlideScope can be used for routine intubations and can also be considered an alternative airway device for difficult or failed airways. The device's distal angulation makes it ideally suited to visualize and intubate an anterior larynx where direct laryngoscopy has proven unsuccessful. Because it does not require direct visualization of the larynx through the mouth, it is useful when cervical mobility or mouth opening is limited. Patients in whom it is desirable to minimize movement of the neck are excellent candidates because little force is needed to expose the glottis with the laryngoscope blade. The GlideScope performs well in the presence of secretions, blood, and vomitus, and thus is a good choice in these circumstances.
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Figure 14-2 • Intubation being Performed in the Emergency Department Using the Standard GlideScope. Note that the operator has the GlideScope placed directly in the midline and is inserting the tube from the right side of the mouth. The inset photo demonstrates what the operator sees on the GlideScope monitor. Note that the larynx appears in the upper half of the view. This is by design so the operator can see and direct the “approach” of the tube to the airway. A small amount of blood is present on the interarytenoid notch and right vocal cord. |
The GlideScope is used in the following manner to perform tracheal intubation (Fig. 14-2). The handle is grasped with the left hand, in the same fashion as a conventional laryngoscope, and the tip of the laryngoscope blade is gently inserted between the teeth under direct vision. The critical point here is to start out in the midline of the tongue and to ensure that the device remains in the midline of the mouth and upper airway. There is no sweeping of the tongue to the left as is done with conventional laryngoscopy. It is difficult to identify landmarks if the blade is off midline. As soon as the tip of the laryngoscope blade passes the teeth, the operator should direct his or her attention to the video monitor and use the landmarks on the video screen to navigate to the glottic aperture. Typically, the uvula will be seen if the blade is correctly situated in the midline. The operator should then continue to walk the blade down the tongue and past the uvula, with a slight elevating motion until the epiglottis is seen. At that point, it is best to continue advancing the blade into the vallecula, with some gentle upward force, to lift the epiglottis out of the way. The blade should ultimately be seated in the vallecula, much in the same way that a Macintosh blade would be. If the glottic view is insufficient, often a gentle tilt of the handle will expose it fully, in contrast to the lifting motion with a conventional laryngoscope. If the glottic aperture still cannot be exposed, the blade can be withdrawn a bit, placed under the epiglottis, and used like a Miller blade to physically displace the epiglottis up and out of the way. The problem with doing this is that this tends to tilt the larynx more sharply, making advancement of the tube into the trachea technically more challenging. Identifying and exposing the glottis is the easy part of using the GlideScope. The challenging part is directing the ETT toward the image of the glottis displayed on the video screen. This is technically more challenging for two reasons. First, the GlideScope video camera is directed at an angle of 50 to 60 degrees, and thus, the angle of attack of the tube is quite steep. The second issue is that using the screen to navigate to the glottis requires some stereoscopic skill and hand-eye coordination that may not come naturally to all operators. The critical factor in getting the tube to enter the trachea is configuring the ETT into a shape that conforms to that of the GlideScope blade before inserting it into the patient's mouth, and for the operator to look directly into the mouth when inserting the tube, until the distal tip of the tube is felt to be in proximity with the distal end of the laryngoscope blade, at which time the eyes are redirected to the video screen to guide the tube through the glottis. There are several options for bending the tube to facilitate insertion. The manufacturer recommends simply bending the ETT to conform to the shape of the GlideScope blade: a gentle curve of 60 degrees. The manufacturer has recently developed a preformed rigid ETT stylet that provides the appropriate curve and angle for the ETT to allow proper placement at the glottic opening. An alternative approach is to bend the tube at a right angle just proximal to the cuff, similar to the configuration of the tube when using the Trachlight (see Chapter 11). The tube is then inserted into the right corner of the mouth and rotated upward, at which point the tip of the tube should be pointing at the glottis. Gentle forward rotation of the tube on the apex of the bend will then allow the operator to align the tip of the tube perfectly with the glottic entrance. Advancement of the tube then allows the tip to pass through the cords under video visualization. At this point, because of the extreme angulation, it is often difficult to continue advancing the tube into the trachea, and thus, it is helpful to withdraw the stylet several centimeters, or even completely, while maintaining gentle steady forward pressure on the tube. In addition, if the GlideScope is withdrawn about 2 cm, the larynx drops down, lessening the angle of attack and thus greatly facilitating further advancement of the tube. As with conventional laryngoscopy, the ETT can sometimes become engaged on the arytenoids, so the manufacturer has developed a GlideRite ETT with a soft tapered tip to facilitate entry of the tube through the glottic inlet. This tube can be used with the GlideScope or any other device.
The only absolute contraindication to use of the GlideScope is restricted mouth opening of less than 16 mm because this is the width of the widest portion of the blade.
The GlideScope laryngoscope blade must be cleaned and disinfected after each use. Gross contaminants and large debris can be scrubbed off with a surgical scrub brush or enzymatically removed with a proteolytic compound such as Enzyme or Medzyme. For sterilization of the blade, Steris, Sterrad, ethylene oxide, pasteurization, or glutaraldehyde are all acceptable and safe. The electrical connector cap should be placed over the contact port on the laryngoscope handle to prevent corrosion of the contacts. The only method of sterilization that is absolutely contraindicated is autoclaving, which involves exposure of the device to very high temperatures that will damage the video camera element. In fact, the laryngoscope blade has a silver temperature indicator that turns black if the device is exposed to temperatures exceeding 80°C.
GlideScope Ranger/Cobalt
The use of the GlideScope Ranger system is identical to the original version, except the slightly increased blade angulation requires less lifting force during laryngoscopy.
Intubation is performed with the GlideScope Cobalt system, as with the other GlideScope units. The major difference between this and the original version is the development of a disposable blade that attaches to a newly designed flexible video baton. The disposable blade, called a Stat, is easily slid over the flexible baton and locks in place with a plastic notched mechanism. This combination provides a similar view to the original GlideScope, and the user can follow the previous recommendations for use. After the intubation is complete, the Stat can be pulled off the video baton and discarded, and another intubation can be immediately performed by simply sliding on a new disposable Stat blade. This design provides a more rapid turnaround time than sterilization. If necessary, the video baton can be cleaned and sterilized similar to other GlideScope units by using a nonautoclavable method such as Sterrad or Steris.
Summary
The GlideScope is a rugged, well-designed device with many features that are compatible with emergency intubation. There are multiple configurations and blade sizes that allow the devices to be used in a variety of clinical situations. Due to its anterior video angulation, superb antifog capabilities, and capacity to maintain an adequate view despite secretions, the GlideScope is one of the most useful videoscopes for emergency intubations.
Karl Storz Video Laryngoscope Intubating System
Device Components
The C-MAC video laryngoscope is a completely new system from Karl Storz in 2008, which replaces the original Storz video laryngoscope (VL), and incorporates numerous improvements. The original VL consists of a fiberoptic and video system integrated into a series of traditional laryngoscope blade styles and sizes. The light provided by this system is more than 100 times greater than the illumination provided by a conventional battery powered Macintosh laryngoscope, but the system is prone to fogging and requires application of an antifog solution to the fiberoptic lens before use. The laryngoscope connects to a conventional fiberoptic light source and video processing unit or to a unified telepak display unit with a flip up eight inch color monitor. The new C-MAC system abandons fiberoptic and conventional video in favor of a CMOS micro video camera, which provides an enhanced field of view and resists fogging, thus requiring no antifog solution. The device incorporates a video recording system, a unique feature among video laryngoscopes that supports both teaching and quality management. The C-MAC is powered by a rechargeable lithium battery, permitting 90 minutes of operation without a power source. A 7 inch video screen with a single cable and straightforward controls greatly simplifies operation over the old VL system (Fig. 14-3). Both the original VL and the new C-MAC are based on specially modified conventional laryngoscope blades, so they do not require a specially curved stylet as is used with the Glidescope. The distally placed video source significantly improves the glottic view when compared to direct laryngoscopy, but for particularly difficult “anterior” airways, it may not be as good as the more sharply angulated blade on the Glidescope. On the other hand, for most airways, tube insertion should be easier with the VL or C-MAC than with the Glidescope because the stylet is shaped as for conventional laryngoscopy, thus permitting more direct insertion and avoiding the impingement on the anterior trachea that occurs with the Glidescope.
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Figure 14-3 • The new C-MAC video laryngoscopy system. The blade incorporates a CMOS image sensor and light system, which conveys the image to the screen via a single cable. Courtesy of Karl Storz Endoscopy. |
As is the case for other video laryngoscopes, the C-MAC blades cannot be autoclaved because this will damage the micro video camera. However, most other types of sterilization, such as Steris, Sterad, and Cidex, are acceptable.
Use of Device
After the C-MAC or VL is brought to the bedside and connected to the monitor, the light intensity is adjusted as desired (continuous range for the VL, three discrete intensity selections for the C-MAC.) A drop of antifog solution is applied to the fiberoptic lens of the VL, but this is not required for the C-MAC. The blade is inserted like a traditional Miller or Macintosh blade with the exception that the traditional tongue sweep is not needed. The operator views the uvula on the screen and follows the midline until the epiglottis comes into view. Then the blade is used in a traditional fashion with blade placement either within the vallecula with anterior lift or under the epiglottis, both providing visualization of the glottic inlet (Fig. 14-4). The angle of attack is less acute than with the GlideScope, and the tube is curved in a similar shape that used for conventional direct laryngoscopy.
Summary
The Storz C-MAC is a dramatic improvement over the prior VL system, with enhancements, including a CMOS video sensor, elimination of fiberoptics, avoidance of fogging, much more simple assembly and operation, portability, and a significantly lower price. The original VL has numerous blade sizes and styles ranging down to a Miller 0, which are easily interchangeable, and a similar array of blades is anticipated for the C-MAC system.
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Figure 14-4 • Intubation using the older style VL. The glottic image is shown in the lower right. Note the traditional curve of the endotracheal tube, as it is being aligned for insertion. Courtesy of Karl Storz Endoscopy. |
McGrath Video Laryngoscope Series 5
Device Components
The McGrath video laryngoscope(MVL) (Fig. 14-5) consists of three main parts. First, the handle of the video laryngoscope is made of latex free medical-grade rubber and stainless steel, housing a single AA battery to power the device and an attached 1.7-inch color LCD monitor. The power button is placed at the top of the handle. Second, the camera module incorporates a light source and a micro-video camera that illuminates the hypopharynx and provides a view of the glottis. The last component is a disposable laryngoscope blade made of medical-grade optical polymer that attaches to the camera stick module and can allow one to manipulate and displace the tongue. The blade can be adjusted into three different positions, creating the desired length to facilitate intubation for various anatomical and patient differences. However, there is not a locking mechanism for the three blade positions, and thus, the potential exists for the blade to slip on tension during intubation. A locking pin keeps the blade from disengaging completely from the handle. The MVL does not incorporate antifog technology, nor does the device incorporate a channel guide within the blade, so any ETT size can be used using a standard stylet.
The LCD screen attaches to the proximal portion of the handle module and can be adjusted for an optimal viewing angle. Placement of the screen at the top of the handle improves operator comfort by allowing visualization of the device and patient simultaneously.
The LCD screen can be rotated to a variety of positions to optimize clarity and can be rotated along the axis of the handle so the device can lay completely flat. The camera, display, and light are powered by a single AA 1.5-V battery providing approximately 60 minutes of operating time. A battery warning indicator begins to flash when little operating time remains. The MVL does not incorporate an auto-off feature, so the device will completely exhaust the battery if left on.
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Figure 14-5 • McGrath Video Laryngoscope. The disposable plastic blade is engaged on the camera stick. The camera stick is in the midposition. Sliding the camera stick forward one notch will lengthen the blade, allowing it to be used for larger patients, while retracting it one notch will shorten it, allowing it to be used for smaller patients. The video monitor is attached to the upper aspect of the handle and can be rotated to the optimal position for viewing. |
The MVL is constructed of durable materials and demonstrates a solid feel in the operator's hand. Because it is essentially a conventional laryngoscope with a small screen attached, it is extremely portable. A protective carrying case is not included with the MVL, increasing the risk of damage during transport.
Use of Device
There is little setup needed for the MVL, and once a disposable blade is placed on the camera stick and the device turned on, it is ready for use (Fig. 14-6). The MVL is inserted into the patient's oropharynx much like a traditional laryngoscope; however, rather than sweeping the tongue to the left, the blade is introduced along the midline. The tip of the blade is then guided into the vallecula and used to lift the tongue anteriorly, similar to a conventional Macintosh blade. The device functions best using a curved blade approach; however, a straight blade technique can be used if needed. The latter technique distorts the anatomical landmarks, however, and is not the recommended technique described by the manufacturer. Once a clear view of the airway, appears on the LCD, the operator uses a standard ETT with a malleable stylet to intubate the trachea while visualizing the process on the video screen. The manufacturer recommends the ETT be bent into a hockey stick shape at a point roughly 5 cm from the tip of the tube. This facilitates advancement of the tip of the tube through the glottic inlet. The MVL is smaller and more portable than the GlideScope and Storz VL, thereby facilitating ease of use; however, this portability increases the risk for theft, loss, and damage.
After intubation, the disposable blade is removed and discarded while the handle is cleaned with an antiseptic towelette. The disposable blade does not protect the handle or proximal portion of the device; therefore, it is susceptible to contamination, and the rubber handle can be somewhat difficult to clean and sterilize. The device cannot undergo Steris or Sterrad sterilization procedures.
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Figure 14-6 • Intubation Using the McGrath Video Laryngoscope. As with other video laryngoscopes, the device is inserted in the midline and can be used with either a straight blade approach or a curved blade approach. The picture shows the view of the glottis as seen with a curved blade approach, which tends to cause less distortion of the laryngeal anatomy and facilitates tube passage. This view was the initial view attained during laryngoscopy. As the blade was left in the patient's mouth during laryngoscopy, the lens became increasingly fogged, making visualization of the structures much more difficult. It is highly recommended that antifog solution be applied to the tip of the blade prior to insertion. |
Summary
The McGrath is a compact, easy-to-use, intuitive device that is the most similar to direct laryngoscopy. The device feels comfortable in the operator's hand and does not require a lot of education or setup time. Therefore, the learning curve is short. The blade is narrower than the other devices, and for patients with large tongues, this can hinder the operator's view. Without the application of antifogging solution, the blade fogs quickly in emergency situations. The delicate nature of the device and lack of an included case make it less suitable for prehospital use.
Pentax Airway Scope, AWS-S100
Device Components
The Pentax airway scope (PAS) consists of two components (Fig. 14-7). The first, an unconventional handle with a more linear design that encompasses a monitor screen, power button, battery compartment, video-out port, locking connection ring for the disposable blade, and a flexible cable that houses the light source and CCD micro-video camera. The PAS has a disposable sleeve that covers and protects the reusable handle from contamination. The second component is a polycarbonate Lexan disposable blade that incorporates an ETT channel and 12F suction port. The blade does not feature an antifog mechanism; however, the Lexan plastic technology used in the blade reportedly resists fogging and contamination. As of this writing, only a single adult-size blade is available that will accept ETT sizes between 6.0 and 8.5 mm internal diameter. The ETT is preloaded alongside the disposable blade with clips that hold the tube in place. The PAS has a green reticle that can be displayed on the LCD screen to guide the user into the correct position for ETT placement. The 2.4-inch color LCD monitor is attached to the handle and can be tilted into various positions to allow easier viewing. The PAS has video output capabilities, allowing the image to be transmitted to an external video monitor or recording device. The PAS is powered by two AA 1.5-V batteries that provide approximately 60 minutes of continuous operation. A low battery indicator flashes to alert the operator when 5 minutes of battery life remain. The PAS has a protective soft carrying case with preformed foam compartments to house the scope, video cables, and extra batteries. The case does not include space to carry blades.
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Figure 14-7 • Pentax Airway Scope. The disposable blade is attached to the rigid handle. On the side of the blade, the tube guide that holds the endotracheal tube in place can be seen. The video monitor is on the upper posterior aspect of the handle and can flip up for easier viewing or for viewing when intubating the patient face to face. The little plastic disc on the side of the handle screws off to allow access to the video-out port. An optional disposable clear plastic sleeve can be placed on the handle to protect it from gross contamination by body fluids. |
The PAS is solidly built of strong orange plastic and stainless steel, and has an ergonomic fit within the operator's hand. The laryngoscope is portable and can easily be transported.
The PAS is anticipated to become available in the United States in 2008.
Use of Device
There is virtually no setup for the PAS. A disposable blade is locked onto the video cable, the plastic sheath is secured, and the device is turned on and ready for use (Fig. 14-8). The operator may select whether he or she wants the reticle displayed on the LCD by pressing the on-off button. Antifog solution is recommended for use because the Lexan plastic resists fogging but does not eliminate it. The device is advanced midline along the posterior pharyngeal wall, resulting in elevation of the epiglottis. If the epiglottis is visualized, a Miller or straight blade technique must be used for successful intubation. The reticle is “aimed” at the vocal cords for appropriate position. The reduction in ETT maneuverability requires the PAS to be positioned correctly in front of the glottic inlet and decreases the operator flexibility to manipulate the ETT. Therefore, the operator does not use a stylet or provide manual control over the distal portion of the ETT. The ETT is advanced from the channel through the vocal cords. The PAS has the option of recording the intubation via the video output port. This feature allows one to record the entire intubation procedure for later viewing and teaching purposes. The PAS can be rinsed in water without submersion and wiped clean. The protective sheath and disposable blade make the PAS easy to clean and quickly ready for another intubation.
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Figure 14-8 • Intubation Using the Pentax Airway Scope. The operator is guiding the tube into the airway by advancing it through the tube guide. No stylet is necessary. The inset photo shows the view of the glottis seen on the attached monitor by the operator. The scope must be positioned so the green reticle is centered over the glottic inlet. Here, the reticle is to the right of the glottic inlet. Also, the tip of the blade must lift the epiglottis out of the way so the tube can pass unobstructed into the airway. |
Summary
The PAS is a well-built device video laryngoscope with outstanding optics. However, the lack of an antifog mechanism can impair the quality of the image and make successful intubation more difficult. A more significant problem with the design of the PAS is the requirement to “dip” the scope along the posterior pharynx to elevate the epiglottis. Therefore, if any secretions such as blood or vomitus are present within this location, the scope becomes contaminated and the operator has complete loss of view, making intubation impossible. Unfortunately, this is not an infrequent scenario for emergency intubations.
Res-Q-Scope II
Device Components and Setup
The Res-Q-Scope II (RQS) contains a main video unit with an attached 2.75-inch LCD monitor that is completely mobile to allow for optimal viewing angles (Fig. 14-9). The device is powered by a rechargeable lithium battery pack. A separate backup emergency power source using four AA batteries is included with the device. A low battery indicator light is displayed on the main video unit. The second piece of the RQS is a disposable laryngoscope blade that contains a channel to preload the ETT and an oxygen/suction port. The blade is currently available in one adult size that will accept ETT sizes between 6.0 and 8.5 mm internal diameter. The preloaded ETT is directly inferior to the camera position and is advanced superiorly into the glottic opening. The device contains a video outport for recording. The blade connects to the main video unit via a standard nine-prong VGA connection.
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Figure 14-9 • The Res-Q-Scope II. The video monitor attaches to the top of the device and can be flipped or rotated to virtually any position for optimal viewing by the operator. The tube guide is on the posterior aspect of the laryngoscope blade, and an endotracheal tube can be seen within it. As can be seen, the proximal portion of the tube is directed laterally, and the scope is removed from the mouth after intubation while extracting the tube laterally. A video-out port is present on the top of the main unit (blue piece). |
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Figure 14-10 • Intubation Using the Res-Q-Scope II. Note that the distal placement of the video camera results in an extreme close-up of the airway. Poor illumination, coupled with a low-quality video camera, and low-resolution screen results in an unacceptably poor image of the airway. Lack of an antifog feature further degrades the visibility of the airway. The glare at the top of the screen is from the focused light source of the device and is not artifact. |
The RQS comes with a durable metal case that houses the device extra battery pack, video cables, and two blades. However, the RQS is less sturdy overall than other devices.
Use of Device
The RQS requires little setup time. A disposable blade is connected to the main body of the RQS; however, on occasion, the blade can be difficult to connect, and some minor manipulations must be made for adequate connection. The RQS does not have antifog capabilities, and antifog solution cannot be used because there is no protective cover for the video lens. Therefore, the device is very prone to fogging during intubation. The device is turned on, and instead of insertion via midline, the device is inserted perpendicular to the axial plane at the lateral border of the mouth, and then rotated 90 degrees while advancing the scope into the hypopharynx (Fig. 14-10). If a midline insertion is needed, it will be difficult given the bulk of the device, and the anterior chest wall can impede the insertion of the RQS due to its length. The light source of the RQS is suboptimal, providing weak illumination and a poor view of the anatomical structures. The device should be inserted along the posterior pharyngeal wall and used to lift the epiglottis, providing a view of the glottic inlet. The ETT is advanced from the underside of the RQS and through the vocal cords. However, given the superior direction of the ETT advancement, the view of the glottic inlet can be impeded during intubation. After intubation, the disposable blade can be discarded, and the RQS body wiped with an antiseptic towelette.
Summary
The RQS is an inexpensive alternative to the more costly video laryngoscopes previously mentioned. However, despite the cost savings, the functionality of the RQS, including the optical quality, illumination, and significant lens contamination and fogging, is unacceptable. Therefore, based on the aforementioned limitations and problems with this scope, it cannot be recommended for emergency airway management.
Conclusion
Video laryngoscopy is progressing at a rapid pace, and the technique generally provides a superior glottic view with less effort than with direct laryngoscopy. Video laryngoscopy is an invaluable tool both in routine emergency airway management and as a first-line adjunct for difficult airways. The video-assisted laryngoscopes will outperform conventional laryngoscopy in those patients with reduced mouth opening, cervical spine immobility, and head and facial trauma. Several models have disposable versions that greatly reduce cleaning time and the potential spread of infectious agents. We have also discovered additional areas where these devices are particularly helpful: confirmation of ETT placement for patients in whom tube location is in question, visualization of upper airway obstructions and foreign material, and aiding in difficult tube exchanges. Most important, all video-assisted laryngoscopes allow real-time feedback for assistance or airway management education. The instructor can provide advice for successful intubation while allowing the operator to maintain control of the scope.
Direct laryngoscopy for the purpose of endotracheal intubation was introduced into clinical medicine almost 70 years ago. Since then, little has changed in its application and performance. The development of video laryngoscopes over the past few years, typified by the GVL, is the most innovative advancement in the field of laryngoscopy and intubation made to date. It is likely video laryngoscopy will soon supplant conventional direct laryngo-scopy for emergency airway management.
Evidence
1. What is known about the GlideScope in clinical practice? The GVL is the most extensively studied device since the advent of this technology. Several studies have looked at its performance both in routine intubations and in difficult airway scenarios. Agro et al. (1) compared the glottic exposure achieved with the GlideScope to the view obtained with a Macintosh blade in 15 patients with cervical immobilization. They found that the GlideScope improved the Cormack-Lehane (C-L) view of the glottis by one grade in 14 out of 15 patients. In one patient, who was a grade III airway, the GlideScope did not improve the view of the glottis so the patient was intubated with the aid of a bougie. The glottic views in this series of patients were poor during conventional laryngoscopy, when compared to a routine operating room (OR) population or to previous intubation studies, suggesting a difficult airway cohort, although the author did not report this. For example, using a standard Macintosh blade, 1 patient was a grade 4, 9 patients were grade 3, 5 patients were grade 2, and no patients were grade 1. Thus, in this small series, the vocal cords could be identified in only 5 out of 15 patients (33%), compared with 95% in routine OR series. In an abstract by Sakles et al. (2), the GlideScope (GVL) was compared to two fiberoptic airway devices, the UpsherScope (US) and the Shikani optical stylet (SOS; see Chapter 13). Emergency medicine residents with no prior experience with these devices were asked to intubate manikins, and the success rate for each device and the time needed to perform the intubation was evaluated. The GVL was successful 100% of the time and, on average, required one attempt and 65 seconds to perform the intubation. The US had a success rate of 71% and, on average, required 1.4 attempts and 65 seconds. The SOS was successful in only 43% of the cases and, on average, required 2.2 attempts and 128 seconds. Sun et al. (3) performed the only randomized clinical trial comparing the GlideScope to direct laryngoscopy. Two hundred healthy preoperative patients were randomly assigned to laryngoscopy with either a conventional Macintosh 3 blade or GlideScope. All patients were initially assigned a C-L grade by a separate anesthetist using a Mac 3. In most patients with C-L grade >1 (28/41), the laryngoscopic view was improved using the GlideScope, and nearly all patients with a C-L grade 3 or higher view had improvement in glottic exposure. However, time to ETT placement took an average of 16 seconds longer in the GlideScope group. In 2005, Cooper et al. (4) published a multicenter trial with 728 consecutive patients evaluated with both direct laryngoscopy and the GlideScope. Nearly all patients (99%) had a C-L grade of 1 or 2 using the GlideScope, which significantly improved a poor direct laryngoscopic view in the majority of cases. Intubation success was 96%, and failed intubations occurred despite adequate visualization, again suggesting that difficulty with ETT manipulation can impair intubation success. A 90-degree angle placed proximal to the cuff has been suggested as the optimal ETT shape to help facilitate tracheal intubation (5,6). A smaller performance assessment in 50 preoperative surgical patients again showed laryngoscopic superiority of one to two C-L grades using the GlideScope compared to direct laryngoscopy (7). In simulated difficult airway scenarios, the GlideScope also seems to perform equal to or better than direct laryngoscopy. A recent manikin study evaluated 30 anesthetists using a MacIntosh laryngoscope versus the GlideScope in three simulated difficult airways: cervical rigidity, pharyngeal obstruction, and tongue edema (8). Although numbers were small, the GlideScope was superior to direct laryngoscopy in the pharyngeal obstruction scenario. There was no significant advantage in the other settings. Other smaller studies have shown similar results with the GlideScope significantly outperforming conventional Macintosh laryngoscopes both in preoperative patients and in selected difficult airways such as ankylosing spondylitis (9,10). Overall, the GlideScope appears to be superior to direct laryngoscopy in providing optimal visualization of the laryngeal inlet and vocal cords in both routine and difficult airways. The data suggest a slightly longer time to tube placement; however, an ETT configuration that includes a 90-degree angle may expedite intubation. Specialized, preformed ETTs with angled tips and easily retractable stylets are now available. Due to their more recent introduction, there are no published studies yet evaluating the GlideScope Ranger or the GlideScope Cobalt. Currently, data are being gathered with respect to the GlideScope's use in emergency airway management as part of the National Emergency Airway Registry Project (NEAR).
2. What are the advantages of the Karl Storz Video Laryngoscope Intubating System? Two recent studies have evaluated the VL compared to direct laryngoscopy and the GlideScope, respectively. Kaplan et al. (11) published a large prospective multicenter trial of 865 patients undergoing general anesthesia with paralysis. The operator would obtain the best view with direct visualization then record the best view using the video monitor. Intubation was then performed using the video monitor. Visualization was considered easy when a C-L grade 1 or 2 was obtained by either method and was significantly easier using the video monitor when compared to direct visualization. In addition, maneuvers such as external laryngeal manipulation and BURP (Backward, Upward, Rightward Pressure) were less often needed for adequate visualization with video assistance. In addition to improving glottic exposure, the video laryngoscope will likely become an effective teaching tool for airway managers in training (12). There are no published studies to date evaluating this tool in emergency department populations, but the NEAR V–EVAL (Emergency Video-Assisted Laryngoscopy) study is currently underway.
3. Are there any studies related to use of the McGrath Video Laryngoscope? Only one study has evaluated the MVL. Shippey et al. (13) described their initial experience in 75 preoperative patients, all with normal airway anatomy. This small prospective single-center study recorded intubation success rates, laryngoscopic view, and time to ETT placement, and found that in nearly all patients (99%), a C-L grade 1 or 2 was obtained with an average time of 6.3 seconds needed for optimal visualization. Overall success rate was 98%. Although this preliminarily shows promise for the MVL, more study is needed before a firm recommendation can be made.
4. What is the experience with the Pentax Airway Scope? There is little published about this device. Suzuki et al. (14) published their experience with 100 patients undergoing elective surgery and compared the C-L grade obtained with the Macintosh laryngoscope with that of the PAS. They were able to obtain grade 1 views on every patient using the PAS and in 65% of patients using a conventional laryngoscope. Any recommendation about this device is premature, and its performance in difficult or emergency airway situations has not been adequately studied.
5. Are there any data supporting the use of the Res-Q-Scope? No studies are published as of this writing.
References
1. Agro F, Barzoi G, Montecchia F. Tracheal intubation using a Macintosh laryngoscope or GlideScope in 15 patients with cervical spine immobilization [letter]. Br J Anaesth 2003;90:705–706.
2. Sakles JC, Tolby N, VanderHeyden TC, et al. Ability of emergency medicine residents to use alternative optical airway devices. Paper presented at the Western Meeting of the Society for Academic Emergency Medicine; April 2003; Phoenix, AZ.
3. Sun DA, Warriner CB, Parsons DG, et al. The GlideScope video laryngoscope: randomized clinical trial in 200 patients. Br J Anaesth 2005;94(3):381–384.
4. Cooper RM, Pacey JA, Bishop MJ, et al. Early clinical experience with a new video laryngoscope (GlideScope) in 728 patients. Can J Anaesth 2005;52(2):191–198.
5. Dupanovic M, Diachun CA, Isaacson SA, et al. Intubation the GlideScope videolaryngoscope using the “gearstick technique.” Can J Anaesth 2006;53(2):213–214.
6. Jones PM, Turkstra TP, Armstrong KP, et al. Effect of stylet angulation and endotracheal tube camber on time to intubation with the GlideScope. Can J Anaesth 2007;54(1):21–27.
7. Rai MR, Dering A, Verghese C. The GlideScope system: a clinical assessment of performance. Anaesthesia 2005;60(1):60–64.
8. Benjamin FJ, Boon D, French RA. An evaluation of the GlideScope, a new video laryngoscope for difficult airways: a manikin study. Eur J Anaesthesiol 2006;23(6):517–521.
9. Hsiao WT, Lin YH, Wu HS, et al. Does a new video laryngoscope (GlideScope) provide better glottic exposure? Acta Anaesthesiol Taiwan 2005;43(3):147–151.
10. Lai HY, Chen IH, Chen A, et al. The use of the GlideScope for tracheal intubation in patients with ankylosing spondylitis. Br J Anaesth 2007;98(3):408–409.
11. Kaplan MB, Hagberg CA, Ward DS, et al. Comparison of direct and video-assisted views of the larynx during routine intubations. J Clin Anesth 2006;18(5):357–362.
12. Kaplan MB, Ward DS, Berci G. A new video laryngoscope—an aid to intubation and teaching. J Clin Anesth 2002;14(8):620–626.
13. Shippey B, Ray D, McKeown D. Case series: the McGrath videolaryngoscope—an initial clinical evaluation. Can J Anaesth 2007;54(4):307–313.
14. Suzuki A, Toyama Y, Katsumi N, et al. Pentax-AWS improves laryngeal view compared with MacIntosh blade during laryngoscopy and facilitates easier intubation. Masui 2007;56(4):464–468.
