Cutting-edge concepts for airway management
June 1, 1999 6 minutes read
Cutting-edge concepts for airway management
Advances provide options for critical intubation
When you’re faced with a patient with a difficult airway, you need as many options as possible. "There are a number of new approaches in airway management which ED nurses must be aware of," emphasizes Ron M. Walls, MD, FRCPC, FACEP, chair of the department of Emergency Medicine at Brigham and Women’s Hospital in Boston. "It’s extremely important for nurses to keep up to date with these changes."
Here are updates on the latest in airway techniques, equipment, and medications:
• Techniques. The biggest change in airway management over the past 10 years has been the advent and widespread use of neuromuscular blocking agents, especially succinylcholine, to facilitate ED intubation, notes Walls. "Physicians have received additional training in this important technique, either in residency training programs or in special continuing medical education courses," he says.
This permits safer, faster, and more successful intubation using a technique called rapid sequence intubation (RSI). "Emergency nurses should be aware of the principles of RSI, including the application of the Sellick maneuver, which is a posterior displacement of the cricoid cartilage against the interior surface of the sixth cervical vertebral body, compressing the esophagus and, thus, preventing passive regurgitation of gastric contents," says Walls.
Know the drugs used for RSI, the expected sequence, and recommended doses of these drugs, and the monitoring used for rapid sequence intubation, including blood pressure, pulse, oximetry, and end-tidal CO2, recommends Walls.
New devices are emerging
Rapid sequence intubation involves the simultaneous administration of a potent sedative agent, such as etomidate or midazolam, with a neuromuscular blocking agent, usually succinylcholine, to render a patient unconscious and paralyzed for rapid tracheal intubation.
The technique involves pre-oxygenation and other specific steps to achieve tracheal intubation rapidly and safely, with minimal risk of aspiration of gastric contents, Walls says. "This is a technique that ED nurses should be familiar with," he stresses.
Other techniques, such as cricothyrotomy, are not new to ED airway management, but are vitally important, Walls explains. "Cricothyrotomy occurs in about 1% of all ED cases of airway management," he says. "New devices are just coming on-line and ED practitioners can expect to see more of them as time goes on."
• Equipment. New devices are emerging that are useful in the difficult and failed intubation scenario, Walls notes. "The intubating fiberoptic bronchoscope is becoming more widely used in EDs by emergency physicians," he says. "New laryngoscopes, such as the Bullard rigid fiberoptic scope, and new devices, such as the Intubating Laryngeal Mask Airway (ILM) and the lighted stylet, are expanding emergency airway management."
It’s possible to intubate through the Laryngeal Mask Airway (LMA), notes Robert Schneider, MD, FACS, FACEP, residency director of the department of emergency medicine at Carolinas Medical Center in Charlotte, NC. "You can take up to a nine endotracheal tube and pass it through the aperture of the fast track, and right into the glottic opening, [or] use a fiberoptic bronchoscope or pharyngoscope and do direct endoscopy through the LMA or intubate over it," he explains.
The fast track LMA consists of a mask around the glottic opening, Schneider says. "It’s like having a mask around the face, except it’s a mask (the diaphragm portion of the fast track) that fits around the glottic opening, as opposed to fitted securely around the airway. You have an opportunity to oxygenate the patient and then intubate them right through the fenestrations of the device."
Combitubes are another rescue device that EMS personnel might be using, says Schneider. "It’s like the old esophageal obturator airway (EOA) tubes, except you are able to oxygenate the patient with the Combitube even if you inadvertently place it into the airway. With the EOA, you didn’t have an opening at the distal end of the tube. If you were unfortunate enough to place the tube into the airway instead of the esophagus, you were stuck,"
The Combitube may be used in the prehospital setting for patients whose airway reflexes are depressed. "Otherwise, the patient won’t tolerate the tube," Schneider notes. "Some prehospital providers are using the Combitube instead of rapid sequence intubation to oxygenate the patient until they can get them to a primary treatment facility where the patient can then undergo definitive endotracheal intubation."
The Combitube is also used in the ED as a rescue device. "If you have a patient you are unable to intubate, you can put a Combitube in there and continue oxygenation until you can figure out an alternative way of intubating the patient," says Schneider. "But the Combitube doesn’t substitute for having a cuffed endotracheal tube beneath the cords."
Know the basic mechanics of the tube and the principles behind it, Schneider advises. "You have two balloons on the Combitube. The larger one, which is inflated first, is in the hypopharnyx, and that balloon usually takes 100 cc of air. It’s important to blow that up first so it takes on the anatomy of the pharynx, and then inflate the esophageal balloon," he explains.
The oxygenation port of the Combitube differs from the LMA in that it oxygenates by approximation rather than sitting over the glottic aperture like the LMA does, Schneider notes. "The LMA simulates the standard bag that we use, whereas the Combitube is a series of holes placed circumferentially around the tube. You’ve got an obstruction above (hypopharyngeal balloon) and below (esophageal balloon), and you insufflate oxygen, hoping that enough oxygen finds its way into the patient’s airway."
Both are easy devices to pass, says Schneider. "The Combitube is like passing an NG tube. It’s not that difficult, you just need to understand and follow the anatomy," he says. "The fast track LMA is also extremely easy to pass."
In addition, end-tidal CO2 detectors are now so readily available that they should be used for all ED intubations to ensure that the tube has been placed in the trachea and not in the esophagus, Walls reports.
• Medications. "The most important new airway medication may be Rocuronium, a relatively new, more rapidly-acting agent in the same class as pancuronium and vecuronium," says Walls. "This drug can be used in place of succinylcholine, when succinylcholine is contraindicated, to achieve rapid tracheal intubation."
As with all neuromuscular blocking agents, Rocuronium does not sedate the patient, Walls notes. "Concomitant use of a potent sedative or induction agent is necessary, as it is with succinylcholine," he says.
Etomidate is an older induction agent that is finding new life in the ED, Walls reports. "This drug causes rapid loss of consciousness and is more hemodynamically stable than most other available induction agents," he says. "It is commonly used with succinylcholine for RSI."
It is also key to understand the pharmacology of RSI, and know the milligram-per-cc dose is of every agent you’re administering, warns Schneider.
"Ketamine is a perfect example of an agent that comes in two different concentrations. If you think you’re giving the weaker one but you’re actually giving the stronger one, you’re obviously going to get a result that you weren’t anticipating," he says.
Sources
For more information about airway management, contact:
• Robert Schneider, MD, FACS, FACEP, Carolinas Medical Center, Department of Emergency Medicine, P.O. Box 32861, Charlotte, NC 28232. Telephone: (704) 355-3181. Fax: (704) 355-7047. E-mail: [email protected].
• Ron M. Walls, MD, FRCPC, FACEP, Department of Emergency Medicine, Harvard Medical School, 75 Francis St., Boston, MA 02115. Telephone: (617) 732-5989. Fax: 617-278-6911. E-mail: [email protected].
• An emergency airway course features an intensive, hands-on workshop that focuses exclusively on ED airway management, including rapid sequence intubation, surgical airway management, rescue devices such as the LMA, Combitubes, lightwand, special approaches to the difficult airway, and pediatric airways. For more information, contact Ron Walls, MD, FRCPC, FACEP, by e-mail at [email protected], or call (617) 732-5989.
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