Prehospital Airway Management: Making the Right Choice
James J. Augustine // May 18, 2012
The presenting symptoms were similar to many other incidents in emergency care: confusion, disorientation, garbled speech and headaches. But this is actually a description of the EMS providers walking through the exhibit area of the big EMS meeting…
They were listening to multiple speakers in conference sessions, and looking through dozens of exhibits of new products that relate to airway management and ventilation for the EMS provider. How are EMS leaders and providers going to address the patient needs for a safe and effective airway in this time of expanding options?
The need for airway management remains the "A" goal in every trauma, cardiac, medical and pediatric algorithm designed for emergency care. There have never been the huge number and types of options now available for managing the airway, available to first responders, Basic Life Support (BLS), and Advanced Life Support (ALS) personnel.
EMS providers must be skilled in managing airways and ventilation using multiple devices, from airways using oral, nasal and tracheal devices; then attaching them to ventilating machinery that delivers oxygen, ambient air, and medications at various mixtures, rates and pressures.
With each type of patient encounter, the combination of devices must be chosen to improve the patient outcome or to minimize risks of a bad outcome. These two goals drive the choice of products that are purchased and placed in service, accompanied by the needed training to successfully use the devices in patient care.
Prior generations of EMS providers had basically three choices of managing an airway. They were using an oral or nasopharyngeal airway; endotracheal intubation through the nose or the mouth using a laryngoscope; or invasively placing a needle or tube through the neck and into the trachea.
Ventilation was performed through a bag valve mask (BVM). While each of these options is still available, there are many more options to ultimately manage the airway and ventilate. It has also been very clear that devices that work well in anesthesia testing are not necessarily devices that work effectively in emergency care.
The reason is very simple: anesthesia patients have an empty stomach, are not going to be moved through a building, and are often medicated to a point of being sound asleep and flaccid. In the EMS field, those conditions only occur when the patient is dead.
Our current EMS challenges are finding the combination of equipment and procedures that will work in struggling patients who still have muscle tone, usually have a full stomach and are going to need to be moved both horizontally and vertically as part of their emergency care. And our equipment and procedures need to be flexible enough to manage humans of every single size and every environmental condition.
The best airway management possible is the one that the patient does him or herself. Providing support to a patient so he or she can maintain an airway is always the best first option. Positioning is the best method of airway management in many injured and ill patients, especially for the first arriving crew.
In appropriate cases of injured patients, spinal immobilization should be performed simultaneously with an upright or lateral position for adult and pediatric patients. Ventilation and oxygenation can be supplemented with a cannula, a mask, or a BVM.
In adult patients, Continuous Positive Airway Pressure (CPAP) can be used to augment ventilation and oxygenation in a patient who is breathing on his own, and has an intact face to strap the mask to.
There is growing evidence to indicate that cardiac arrest patients can be managed with passive oxygenation and little or no assisted ventilation, until it is proven that high efficiency chest compressions and the first rounds of electrical stimulation of the heart (defibrillation or cardioversion) are not restoring cardiac function.
In all other critical EMS patient encounters, the combination of devices must then improve patient outcome or minimize risks of a bad outcome. Why have we chosen endotracheal intubation as the gold standard for essentially all emergency patient groups? Intubation allows the EMS provider to relieve or prevent obstruction, provide assisted ventilations in a patient that is not able to adequately inhale, to prevent aspiration of stomach contents, blood and other foreign material, and to help the patient manage secretions.
Intubation is a dangerous procedure if it will cause obstruction or result in a tube in the esophagus, put the patient at risk of aspiration, result in long periods of oxygen desaturation, or prevent adequate exhalation (which is the risk when intubating the severe asthmatic patient).
Airway maneuvers and devices are also dangerous if they cause damage to upper airway structures that lead to bleeding, infections and long term loss of voice and swallowing functions.
Our airway procedures and equipment are enhanced by a new range of monitors and ventilation devices that result in tremendously less risk of placing a device that causes short or long term hypoxemia or obstruction. Pulse oximetry and capnography devices allow the EMS provider to instantly acknowledge poor oxygenation or ventilation and a tube that is in the esophagus or obstructing the trachea.
Still at the top of important airway devices is a size range of oral and nasopharyngeal airways, with an accompanying BVM. For essentially all emergency patients, the correct placement of one of these devices allows seconds to minutes to choose and place more advanced tracheal tubes or rescue airway devices .
If there is obstruction to the larynx or trachea, a deeper device will have to be utilized, but that is only a small number of emergency patients. The simple oropharyngeal airway device has been enhanced with a set of modifications to the distal end that facilitate ventilation closer to the larynx, and/or facilitate the placement of an endotracheal tube.
That is essentially what a laryngeal mask airway (an LMA) is, and its newer cousins (AirQ and I-Gel). The simple BVM has also been enhanced to allow controlled pressure and flow (the Smart Bag).
A huge array of devices are now available to improve the success rate of endotracheal intubation through the nose or the mouth. Beyond the basic direct laryngoscope are now mechanical devices that increase the available light, improve the angle, and guide the tube toward the trachea. These devices may have visual enhancements and ports to channel away secretions, blood or emesis.
Among all these choices, the EMS providers and the system's medical director must have essential protocols for use, and make decisions about how to stock and train on the items that will allow the best outcomes.
There is also a cost to all of these devices. As a priority, for all of the devices, the providers must be adequately trained in to manage the care of adult and pediatric, trauma or medical, patients. Each patient may have different needs for oral, nasal and rescue airways.
A couple of training scenarios
A cardiac arrest patient has priority need for quality and high efficiency chest compressions, and use of defibrillation and/or cardioversion. The airway protocol may include protection from aspiration, use of an appropriately sized oral airway, and passive ventilation with supplemental oxygen mask or assisted ventilations with a rate of 8 to 10 breaths a minute. Only after return of spontaneous circulation will endotracheal intubation be considered.
A patient with an exacerbation of heart or lung disease may present in respiratory distress, and need airway and ventilator management. The airway protocol may include keeping the patient in his/her preferred position, using pulse oximetry to guide oxygen therapy, and applying CPAP to assist the patient who is showing signs of respiratory distress.
For the medical patient who is no longer able to maintain oxygenation or ventilation, or unable to clear secretions, or is vomiting, the protocol will include endotracheal intubation by qualified Advanced Life Support personnel.
The protocol may allow for drug assistance to help the patient accept the airway, and a period of pre-oxygenation to reduce the impact of the airway intervention. The protocol is likely to include the need to pick an appropriate size tube, leave the patient in a position that will minimize the risk of aspiration, monitoring the patient for hypoxemia and stopping the airway attempt if it occurs, and securing the tube once it is placed a certain distance below the vocal cords.
Tube placement must be confirmed with an appropriate device at the time of placement, and at regular intervals afterward as the patient is moved to the Emergency Department. A rescue airway option for a medical patient who cannot be intubated must include the sizes needed for very small and very large patients.
Patients with wheezing will be provided a medication nebulizer and supplemental oxygen, with consideration of giving other medications by intravenous and subcutaneous routes. As mentioned previously, endotracheal intubation of the asthmatic patient is usually avoided, because the tube often worsens the patient's condition. Instead, the airway is maintained with a simple oral or nasal device as further medical therapies are deployed.
A child who has suffered a respiratory or cardiac arrest has airway and ventilation needs that must be managed using pediatric devices. Many pediatric protocols are written to include first line use of oral airways and BVM ventilation, with perhaps one attempt at endotracheal intubation using an appropriately sized tube.
Rescuers should anticipate that a child will vomit and avoid maneuvers that insufflate the stomach. Few rescue airways are manufactured in sizes for children.
In a trauma case where the patient's airway or chest is already unstable, all airway interventions must take into account the need for ongoing spinal movement restriction.
Common elements of the trauma airway protocol include the need to prepare an oral airway, a nasal airway, several endotracheal tubes and the rescue device available for either failed endotracheal intubation, or to capture an invasive airway in the patient's trachea. The protocol will include devices for securing and maintaining the tube in the proper place while the patient is maintained in trauma packaging.
A number of pre-hospital studies1,2,3,4,5,6 underscore the dangers of pre-hospital airway management and the need to have ongoing monitoring to assure that tubes are in the correct place. All EMS airways should be approached with extreme caution, and EMTs provided with the training to use back-up rescue plans.
Providers and medical directors face many options for purchasing and placing each of these devices in service. After choices are made for basic airways, rescue devices must be purchased that meet the needs of the patients and the providers. Rescue airways have an important place in EMS. The selection of rescue airways is an important one, not for the airway that is ultimately selected, but for the training in proper use and patient selection that must be made.
1. Denver Metro Airway Study Group: A Prospective Multicenter Evaluation of Prehospital Airway Management. Prehosp Emerg Care. 13(3):304-10. 2009
2. Guyette FX, Wang H, Cole JS: King Airway Use By Air Medical Providers. Prehosp Emerg Care. 11(4):473-476, 2007
3. O'Connor RE, Slovis CM, Hunt RC, et al. Eliminating errors in emergency medical services: realities and recommendations. Prehosp Emerg Care.6:107-113. 2002
4. Katz SH, Falk JL. Misplaced endotracheal tubes by paramedics in an urban emergency medical services system. Ann Emerg Med. 37:32-37. 2003
5. Jemmett ME, Kendal KM, Fourre MW, et al. Unrecognized misplacement of endotracheal tubes in a mixed urban to rural emergency medical services setting. Acad Emerg Med. 10: 961-965. 2003
6. Jones JH, Murphy MP, Dickson RL, et al. Emergency physician verified out-of-hospital intubation: miss rates by paramedics. Acad Emerg Med. 11:707-709. 2004