Maintaining the airway is everything. The difference between a successful surgery and a devastating result rests in properly maintaining control of this delicate passage. From controlling sedation levels to using tried and true equipment to discovering the benefits of some new LMAs, here are tips and techniques for better airway management.
Avoid over-sedation. The first thing to consider in proper airway management is the depth of sedation; specifically, don't over-sedate your patients. For moderate sedation, the patient should be able to maintain his own airway and respond to verbal stimuli. As one of my mentors said, "It's hard to kill a breathing patient."
When administering sedation, especially for the geriatric population or those with complex medical conditions, go slowly and give the medications time to work. A direct monitor of breathing can also help. Changes in pulse oximetry are a late finding of apnea. Some companies are developing transcutaneous carbon dioxide monitors that may help in detecting over-sedation in spontaneously breathing patients. In the past we used a precordial stethoscope - it sat on the chest and was connected to an earpiece so that you could hear heart and breath sounds; this is still a valuable monitoring tool.
Remember the facemask. But what if the patient needs more sedation? The old standby - the facemask - is far from obsolete. We typically begin preoxygenation through a simple facemask. Adding mask straps to hold it in place frees up your hands the way the newer equipment does. It also minimizes the cost of maintaining an airway since you don't need to open any other devices. A rolled towel or bath blanket behind the neck helps tip the head back a bit and opens the airway. I like to pad the straps as they come over the cheekbones with a folded gauze pad to minimize pressure over the facial nerve. You can add an oral airway (Guedel or other designs) to maintain airway patency. Don't forget that a little continuous positive airway pressure (CPAP) can help splint open the airway with a facemask. This is the most economical way to manage the airway in many patients.
Take advantage of LMAs. Sometimes, the anesthesia provider needs to clear the facial area and get his hands out of the way so surgeons can accomplish the procedure. Then there are those beards and prominent noses that make the mask fit difficult. Maybe there's not a specific indication for endotracheal intubation. Also, intubation typically requires drugs to facilitate laryngoscopy and seems more invasive. Fortunately, there's been an explosion in technology to help in those situations when a facemask is inappropriate.
The first-to-market is the venerable laryngeal mask airway (LMA). Originally only available in a reusable silicone form (now known as the LMA-Classic), it is now available in many styles. These include the LMA-Fastrach, LMA-Unique, LMA-Flexible and LMA-ProSeal. While you can use the LMA-Classic as a bridge to fiberoptic intubation, the LMA-Fastrach is specifically designed to minimize obstruction to the fiberscope and passage of the endotracheal tube. The Portex Soft Seal Laryngeal Mask resembles the LMA-Unique as it is a single use cuffed device that is inserted into the pharynx and cups the glottic opening. The Cobra Perilaryngeal airway supports the airway soft tissue and opens the airway while using a cuff to provide a seal for assisted or controlled ventilation. A similar device is the PAXpress oropharyngeal airway. The Streamlined Liner of the Pharynx Airway (SLIPA) is another supraglottic device. Unlike the previous devices, this is an uncuffed device that allows for supported ventilation.
The Mask Market: What's New in LMAs
The elusive airway - it is the bread and butter (and bane) of every anesthesia providers' existence. There are significant advances in the management of the surgical patient airway in recent years - both for routine anesthesia, and for the urgent/emergent rescue of a difficult airway.
LMA North America was the first to stake claim on a safe and versatile made-for-the-operating room, non-endotracheal tube airway. Their LMA, at this moment, can claim to be the only supra-laryngeal airway that is listed on the ASA difficult airway algorithm. That said, we all don't drink Coke, and many people like Pepsi even better. There are other LMA-type airways out there. In addition, several companies entered the fray with very attractive airway enhancement devices for management of the difficult airway in both everyday and emergency situations.
Nellcor/Tyco introduced a full line of disposable laryngeal mask airways that come in eight incremental sizes. Unlike the original LMA, the inflation tubing doesn't reside in the tubing itself, but instead runs across the top of the dome of the airway, purportedly preventing rollover. The product also has an epiglottic shelf/barrier that prevents the epiglottis from closing off the airway. Lastly, Nellcor/Tyco emphasizes that its airway contains no crossbars, thus allowing a suction catheter to be passed easily through the opening.
Mercury reps will tell you that their CookGas ILA (intubating laryngeal airway) is easier to place than the original LMA because of its oval-shaped top. The oval shape is touted as a built-in prevention to the irritating tendency of these types of airways to fold-over or flip-flop during placement or maintenance. With a keyhole-shaped airway, you can fit up to a size 8.5 endotracheal tube - and any type of endotracheal tube will work with the ILA. The ILA is reusable and autoclavable up to 40 times.
For the enhancement of difficult airway management, many new products will be available within the next year. As examples, LMA North America has the C-Trach (a combination endoscope-intubating device that features a monitor for viewing the trachea that sits right on top of the LMA handle) and Medline has the EndoFlex endotracheal tube. The EndoFlex lets clinicians rapidly and safely adjust the tube's tip to handle a variety of potentially difficult airway situations. With an attachment, the EndoFlex lets you bend the flexible tip to fit in anatomically challenging locations. Olympus has the PortaView LF intubating fiberoptic scope and the PortaView LF-V videoscope with a CCD chip at the tip so you can take pictures. The Olympus models let you enable the zoom on the fly in difficult intraoperative conditions. Rounding out this group, Karl Storz added a battery light source to its video laryngoscope, providing a strong light to the portable semi-rigid intubating telescope. This device allows projection of the airway image on an OR monitor.
For anyone who has ever struggled with a folding/bending/flip-flopping LMA airway or an emergency difficult airway situation, the biomedical industry has afforded us consumers a healthy playing field of competition and many exciting new products from which to choose.
- Adam F. Dorin, MD, MBA
Some advantages of these devices over the traditional facemask include:
- freeing up the providers' hands for other tasks;
- aiding in ventilation for patients with redundant pharyngeal tissues/big tongues that may partially obstruct the airway; and
- easier use than a facemask in bearded patients.
Patients may need lighter depths of anesthesia to tolerate supraglottic devices than an endotracheal tube, which is important to consider if you plan local anesthesia for post-operative or pre-emptive analgesia. Also, patients may have a lower incidence of sore throats and coughing at emergence. If a patient has a history of asthma, the supraglottic devices help avoid triggering bronchospasm from endotracheal intubation.
Where these devices really shine, however, is in emergency airway management. Most healthcare providers who aren't anesthetists or anesthesiologists don't perform endotracheal intubation often enough to be comfortable with the technique. However, these devices, as well as the Laryngeal Tube Airway, EasyTube and the Combitube, are easier to place than an endotracheal tube and thus may be better for the occasional provider as a rescue airway device. However, even the experienced anesthesia provider should have one of these devices available for the unexpected difficult ventilation/difficult intubation patient.
You can sterilize/autoclave reusable laryngeal masks up to 40 times. The single-use, disposable devices may be preferable in areas that don't plan on general anesthesia, such as endoscopy suites, because they have lower acquisition costs and eliminate the issues of processing for re-use. The major players in the disposable laryngeal mask market are Portex SoftSeal, Intersurgical Solus, Ambu Laryngeal Mask, LMA Unique, and, most recently, the LaryngoSeal Laryngeal Mask.
Be aware of laryngoscope upgrades. There is nothing like the old standby laryngoscope for the majority of endotracheal intubations, especially since the development of fiberoptic bundles to transfer the brighter light from halogen lamps for better visualization.
There are some new advances in this. The McCoy laryngoscope and the Flexiblade have controllably flexing tips that may enhance the view of the larynx by allowing a little more upwards motion without levering on the upper teeth. You can use the gum-elastic bougie as well as endotracheal tube changers in combination with the laryngoscope when the visualization is poor. If the view is difficult, placing the thin bougie (Eschmann Tracheal Tube Introducer, Portex Tracheal Tube Introducer) or tube changer (Sheridan TTX Exchanger, Cook Airway Exchange Catheter) may be easier than the larger endotracheal tube. Once placed, you can guide the endotracheal tube over it. I prefer the tube changer since it's hollow and you can use it to deliver some oxygen to the patient.
Another type of tool is the lighted stylet (Light Wand or TrachLight). This uses the principle of transillumination to identify the trachea in a blind intubation technique. While a good trick to have up one's sleeve, the learning curve may prevent relying on this for unexpected use.
In addition, NovaMed provides an MRI-safe laryngoscope. These handles and blades afford clinicians a solution for emergency intubations without the need to remove the patient from the magnetic resonance (MR) environment.
Avoiding Airway Complications
Liability from difficult airway management arises throughout the perioperative period, with two-thirds of this liability occurring on induction of anesthesia and one-third occurring during maintenance, emergency or recovery from anesthesia, a researcher has found.
A recent review of legal claims found that difficult airway claims mostly involved perioperative care (88 percent) and arose throughout the perioperative period: 66 percent upon induction, 15 percent during surgery, 12 percent at extubation and 5 percent during recovery, says Karen B. Domino, MD, MPH, a professor of anesthesiology at the University of Washington School of Medicine in Seattle. Dr. Domino reviewed 187 difficult airway management claims in the ASA closed claims database for her study.
Dr. Domino explained how major perioperative airway complications might be avoided to improve patient safety in a presentation before the New York State Society of Anesthesiologists' December 2004 Postgraduate Assembly in Anesthesiology. She began by citing the American Society of Anesthesiologists' 2003 practice guidelines' recommendation that an airway exam and review of a patient's anesthesia records should, whenever possible, precede the initiation of anesthetic care and airway management. "The intent of the history and physical exam is to detect factors and physical characteristics that may indicate the presence of a difficult airway," she writes in an abstract of the presentation.
Since induction of anesthesia led to difficulties in two-thirds of the cases studied, Dr. Domino says you should consider airway management methods. "Awake intubation has been advocated as the safest technique to secure the airway in a cooperative patient for a difficult airway," writes Dr. Domino. "Our data suggest that awake intubation in the setting of anticipated airway difficulty is an underused safety strategy."
Difficulties in the other one-third of cases occurred during maintenance, emergency or recovery situations. According to the guidelines, she notes, staff members should develop a plan for managing difficult airways in a number of different situations.
"The rescue ability of emergency non-surgical ventilation techniques may have been reduced by the effects of multiple preceding attempts at conventional intubation," writes Dr. Domino. "Persistent attempts at intubation were associated with poor outcome."
- David Bernard
Look for improved visuals. When direct laryngoscopy is difficult or impossible, there are numerous aids to improve the visual field, most employing fiberoptic technology in some form. Several of these are on the market, but they're expensive to acquire and maintain.
A traditional intubating fiberscope (Olympus, Karl Storz and others) is a smaller diameter than a standard bronchoscope and will fit through a smaller endotracheal tube (generally about a 5mm- or 5.5mm-internal diameter rather than the 7mm-diameter for a bronchoscope). The GlideScope is a little different in that the camera is in the blade of what would be a traditional laryngoscope and sends the signal along embedded wires to the monitor. Wires are easier to maintain than traditional fiberoptic bundles that are notorious for being easily damaged.
Other devices use a combination of the traditional metal blade with fiberoptic technology. These include Bullard Laryngoscope, the Wu Scope and the Upsher Scope. These devices have the advantage over video scopes in that they're self-contained - they have a light source, eyepiece and fiberoptic bundled all together. Their use is similar to the standard laryngoscope, except that you don't need to establish a direct line-of-site. They may be easier to use for the occasional user than a flexible fiberoptic scope would be.
One new device, the Shikani Seeing Optical Stylet, consists of a handle that contains a light source and a malleable section that lets it conform to the patient's anatomy. Direct viewing through the eyepiece is straightforward. The advantages of this device over a traditional flexible fiberscope is that steering the tip is more intuitive, it is more compact and is less likely to be damaged in storage.
Tips to remember
When all is said and done, here are some simple tips to remember for better airway management:
- avoid over-sedation;
- have the right size facemask available, as well as mask straps;
- have a supraglottic airway device available for the unexpected - either the unexpected difficult airway (for experienced anesthesia providers) or the unexpected need to manage an airway;
- have a fiberoptic (or miniature camera) device available for the difficult airway that requires endotracheal intubation; and
- be familiar with the American Society of Anesthesiologists Difficult Airway algorithm.
Remember that successful airway management incorporates the best of the old with the latest that new technology has to offer.