Circulation 80,350 • Volume 21, No. 4 • Winter 2006   Issue PDF

ASA Meeting Exhibits Feature Safety Themes

John H. Eichhorn, MD

Anesthesia patient safety persisted as a prominent theme in the massive exhibit hall at the American Society of Anesthesiologists Annual Meeting October 12-18 in Chicago. Both the Scientific and Educational Exhibits and also the Technical Exhibits from manufacturers and sellers of anesthesia-related equipment and supplies contained some new approaches to patient safety as well as many familiar themes with a few twists.

In the Scientific and Educational Exhibits, 14 of the 56 entries, 25%, in some way related to airway concerns. This again reinforces the suggestion that airway management remains likely the greatest technical/mechanical challenge for anesthesia professionals, because it is the one central component of practice that has changed the least in the “modern era” of anesthesia, as defined by the widespread adoption nearly 20 years ago of electronic monitors such as oximeters and capnographs to extend the power of human senses and allow much earlier detection of dangerous intraoperative situations. The fact remains that general anesthesia still today very often includes induction of unconsciousness and then paralysis of a patient’s ventilatory musculature when there is no specific certainty or even assurance that intubation of the trachea or even positive pressure ventilation will be possible. Accordingly, virtually all anesthesia professionals still today experience “difficult airway” situations with a frequency that depends on their type of patients and practice. Thus, airway tools of a wide variety, airway models, airway simulators, airway educational efforts, and the associated Scientific and Educational Exhibits as well as airway-related products for sale in the Technical Exhibits continue to constitute an appreciable fraction of the displays.

Among the airway related Scientific exhibits, prominently featured was a comparatively low-tech but apparently very useful new device from Belgium consisting of a specially shaped disposable inflatable bag that is placed under a patient’s upper torso (particularly a morbidly obese patient) and then inflated and adjusted to maximize the sniffing position (slight extension and increase of the sterno-mandibular distance) in order to align the airway and facilitate direct laryngoscopy (potentially replacing the mound of pillows, sheets, and towels or various foam-type inclines now used for this purpose).

Ohio was strongly represented with 2 exhibits from Cincinnati Children’s Hospital on pediatric airway equipment and techniques as well as a display from the Cleveland Clinic about using specialized CT scans to image and analyze airways (not yet by a long shot the long sought-after bedside device to map every patient’s airway preop but a step in that direction). Also from the Cleveland Clinic were 2 other exhibits: one an update for light-wand intubation of a difficult airway with accompanying computerized teaching support and the other a new “stylet forming device” to be used with a video laryngoscope in order to customize the endotracheal tube to a specific patient’s difficult airway. Another display from Cardiff, Wales, stressed the interesting problem that various pediatric laryngoscope blades with the same names are actually of different shapes and give different views of the airway, some better than others. In the educational mode, a French computerized virtual airway program was offered as an improved method to teach in 3-D the fiberoptic “navigation” of the difficult airway.

An exhibit from Baylor in Dallas focused on the problem of dealing with difficult airways in remote locations distant from the OR and its resources and personnel. The extensive display highlighted methods to adapt basic, readily achievable techniques for “the outfield.”

Another exhibit from Mt. Sinai in New York dealt specifically with topical anesthesia of the airway for awake fiberoptic intubation, emphasizing both traditional and new techniques.

Shifting emphasis, the “difficult extubation” was the subject of an entry from Spain and demonstrated a systematic sequential approach first to support extubated patients, and then, when needed, assist ventilation, attempt reintubation, or establish a surgical airway.

While not targeting airway manipulation, an exhibit from UMDNJ-RWJ in New Jersey dealt with a common related problem by featuring a new type of face tent intended to provide supplemental oxygen to sedated patients having upper endoscopy involving a bite block holding the mouth open while avoiding the common problem of CO2 rebreathing in prior efforts of this type. This display was very near the annual entry from the American Sleep Apnea Association and around the corner from the exhibit of the Society for Airway Management, all of which seemed somehow fitting.

Other safety-related topics covered in the Scientific and Educational Exhibits included an extensive presentation regarding fires during monitored anesthesia care, specifically outlining the cause of these fires and best measures to prevent them. An extensive multimedia display from Milwaukee Children’s Hospital highlighted common anesthesia machine mishaps and how to prevent them. Finally, while the potential safety benefits may not be as direct as from some of the other exhibits (but are nonetheless very real), from the same hospital was a provocative display about perioperative interpersonal conflicts and how to manage them. While documentation of anesthesia adverse events being caused or contributed to by “bad blood” between anesthesia professionals and other types of personnel is understandably hard to come by, it is certainly worth trying to prevent such conflicts that can be distracting and disruptive during anesthesia care.

Continuing the theme from the Scientific and Educational Exhibits to the corporate section, excluding the mega-exhibits from the large national companies with multiple product lines across the entire anesthesia spectrum, there were no fewer than 34 of the technical/commercial exhibits exclusively or largely devoted to equipment and supplies for airway management, again dramatically emphasizing the major role of improving airway handling as an ongoing component of the evolution of anesthesia patient safety. One company offered a new interlocking set of foam pillows, similar in purpose to the inflatable bag noted above, for use in positioning the torso, neck, and head of a difficult airway patient (greatly morbidly obese, for example) in the most favorable manner for direct laryngoscopy. Multiple large displays showed a panoply of all manner of airway tools and equipment. This genuinely dizzying array raises the question that there may be too many competing technologies and varieties of equipment available for there to be adequate investigation of their application, risks, and benefits. Frequently characteristic of the commercial marketplace in medical equipment, it appears that several manufacturers have rushed into production of new tools or technologies that have only been “tested” by their inventor and have never been the subject of peer-reviewed publications or multi-center clinical trials. While this quasi-shotgun approach may be entrepreneurially understandable, it makes for such a possibly bewildering array of choices to average anesthesia practitioners that it seems much easier for them to stick with the familiar Mac 3 or Miller 2 rather than try to figure out what may be better, either in general or in “difficult airway” scenarios. So far, there does not appear to be an organized effort by the profession to sort all this out. Further, clever as some of the new devices may seem, their significant cost is enough potentially to prevent their widespread trial, much less adoption, which likely contributes to the very slow pace of improvement in the prevention of the rare but dramatic unexpected airway problems and even overt emergencies upon induction of general anesthesia.

In any case, there were several updates and variations on the fiberoptic and video-assist
ed laryngoscopes, several of which were intended for routine everyday use. Some featured eyepieces, but more of them this year offered miniature cameras and video systems, including some that projected to very small screens (1.7 inch diagonal and attached directly to the laryngoscope handle, which is not much larger than a traditional one), to small free-standing screens that would rest on a stand or the patient’s chest, or to very large video monitors. One relatively large new video-intubation rigid apparatus from an endoscope manufacturer involves a large plastic laryngoscope blade through which an optical/light source bundle fits and rests next to a trough that guides the tube into the larynx under direct video imaging. The 1.5 x 3 inch screen is on the handle and has a sighting target on it that, when superimposed on the cords in the picture, indicates the tube is aimed straight down the larynx. The other manufacturers of fiberoptic bronchoscopes offered added new variations of laryngoscopes incorporating fiberoptics, making new “flexible intubation videoscopes.” Another system featured blades containing integral optics that would fit onto a traditional C battery-powered handle, claiming to give a view around the base of the tongue without the need to displace it as in traditional direct line-of-sight laryngoscopy. A new intubating stylet involves a starting guidewire that is used in the same manner as with the Seldinger technique for a vascular cannula. A new variant of “helpful” endotracheal tube has an integrated articulating tip that bends at the cuff, which is flexed to help approach an anterior larynx without use of a stylet by an internal wire actuated by pulling up on a plastic collar at the connector end of the tube.

Also new this year was a video-enabled laryngeal mask airway with the optics and camera incorporated into a handle similar to existing intubating laryngeal mask airways. The medium-sized screen is attached to the handle by a magnetic latch after the mask is placed in the airway. The manufacturer emphasizes that positive pressure ventilation can be continued during the video-guided intubation attempt, which requires the use of the existing dedicated extra-long endotracheal tubes and then the pusher to allow removal of the handle.

At the other end of the airway-management complexity and technology spectrum was a new product that is nothing more involved than sticky-backed disposable foam tape that is intended to be stuck on a regular steel laryngoscope blade, Mac or Miller, in such a position as to be even with the teeth during laryngoscopy, thus preventing the metal blade from touching teeth and reducing the risk of dental damage. The manufacturer stresses the utility of this remarkably simple “technology,” especially for attempts of new trainees of any type who are starting to learn direct laryngoscopy and endotracheal intubation.

Thematically related to the airway management products was a new emphasis on diagnosing and documenting obstructive sleep apnea preoperatively. One company offers a service that involves specific screening for any suspected OSA patient, including a 1-night, at-home test to help make the diagnosis and then a treatment plan as indicated with emphasis on the immediate post-general anesthetic period. Another company offers a product to be used in the preop screening process. It is a disposable battery-powered plastic strip worn overnight with thermal sensors in front of the nose and mouth that senses breathing pattern and efficiency in a manner that allows the indicator to analyze for the presence of OSA, even the night before surgery. The strip “develops” automatically in the morning and reveals a rating for OSA risk that can be incorporated into the anesthetic plan.

The problem of unintended baro- or volu-trama from leaving the anesthesia machine in manual ventilation mode with the APL (“pop-off”) valve completely closed (usually immediately following intubation) while distracted (say, taping in the tube) can now be addressed with a relatively simple new “ventilator safety valve” that goes between the breathing circuit tubing and the absorber head. It will automatically vent gas from the circuit if pressure exceeds 20 cm H2O for more than 6 seconds, thus preventing the accidental over-inflation of the breathing bag to dangerously high pressure and sometimes a startlingly large volume.

One other main theme of the technical exhibits was information management systems, for which there were 23 companies displaying products. One new entry comes from New Zealand (American headquarters in Nashville) that has automated patient data and an electronic anesthesia record but whose main focus is patient safety through preventing intra-op medication errors. Special drug carriers and organizers, bar-coded syringes, a bar-code reader, and a touchscreen are all integrated into a system that preliminary studies show decreases intraoperative anesthetic drug errors by 41%. Other systems had the expected screens, software, and printers, all with the similar claim that complete, organized, legible information about the anesthetic is, by definition, a safety benefit.

Other interesting new products with slightly indirect patient safety positive implications were seen among the displays. A spring-loaded color-coded syringe to be used to identify the epidural space with loss of resistance to saline automatically and definitively during slow advancement of a Touhy needle appeared to attract significant attention. Regarding maintenance IV infusions of propofol, either for TIVA or sedation, the propofol blood level can be monitored directly by measuring it in real time in the expired breath using a new detector based on “ion molecule reaction mass spectrometry.” A new twist was the new availability of ultrasound machines for purported anesthesia applications; several companies had such offerings. Finally, in a different vein, an interesting new product was displayed that visibly identifies vessels under the skin, greatly facilitating the cannulation of either subject veins or arteries. Near infra-red light in a special delivery system is focused on the skin, which shows green with the underlying vessels clearly visible as dark outlines. The initial offering is a roll-around stand with the device (a little smaller than a football) on an articulating arm; however, company representatives state that a hand-held model is in development.

Overall, patient safety remained a key focus of both types of exhibits at the ASA Annual Meeting. This recognizes both the current success in improving safety and also the significant challenges still remaining, such as, for example, in making genuine changes in practice, leading to lower risk of patient injury associated with issues in airway management.

Dr. John Eichhorn, Professor of Anesthesiology at the University of Kentucky, founded the APSF Newsletter in 1985 and was its editor until 2002. He remains on the Editorial Board and serves as a senior consultant to the APSF Executive Committee.