Endotracheal Intubation: Still the Gold Standard

by Matthew A. Knealing |

Effective and aggressive emergency airway management for the prehospital healthcare provider has been endotracheal intubation for nearly thirty years. In the past 4 to 7 years many medical device companies have invented many new devices that all claim to be better than endotracheal intubation. Many magazines and books targeted towards ambulance personnel and emergency room personnel have debated this topic; one month they will be for endotracheal intubation and the next month be opposed.

This essay will show clinical-based evidence on why endotracheal intubation is still the airway of choice. This paper will also look at the drawbacks that people have brought up about endotracheal intubation as well. Even with modern day advancements, endotracheal intubation is still the gold standard for the pre-hospital provider dealing with emergent airway management.

Before discussing the pros and cons of endotracheal intubation (ET intubation), a few terms and descriptions must be reviewed. Endotracheal intubation is a procedure in which a healthcare provider uses a tool called the laryngeal blade to open a patient’s airway, lift the tongue and visualize the vocal cords which are the opening to the trachea (windpipe) and then place a tube in the trachea (Finucane & Santora, 2003, p. 61).

This procedure is only done when the patient is unconscious or sedated, and has no gag reflex intact. Endotracheal intubation is often performed during cardiac arrest, or during another medical procedure called rapid sequence induction, or RSI, in which patients are sedated and paralyzed so their breathing can be effectively mechanically controlled if they are unable to (Singer, Mervyn, Webb, & Andrew, 2009). These previous mentioned procedures take hours of dedication, trial and error to become efficient at them.

Introduced to the market roughly seven years ago, the King Airway is another option for the emergent airway management. This device tested by the United States Military is a device that is placed blindly, like sticking a large tube into a patient’s mouth and pushing until it cannot go any further. It is meant to be placed into the patient’s esophagus, where a balloon inflates at the end manually via a hollow wire that runs through the device. Once the device is inflated and the esophagus is obstructed, air is then forced into the trachea based on the concept that it has nowhere else to go.

This requires far less training, and has been shown to be an effective backup to ET intubation. The King airway can be placed by emergency medical technicians (EMT’s) nurses, paramedics and physicians. However ET intubation can only be performed by paramedics in the prehospital setting and not their counterpart EMT partners. Paramedic training is roughly 2 years more than EMT training.

Improving Patient Survival
Although a procedure used for over a century in the hospital setting, and over 30 years in the prehospital setting, new information about patient survival linked to ET intubation is still forthcoming. Research has shown that patients with severe head injuries intubated in the prehospital setting have a 10 percent lower mortality rate (Winchell & Hoyt, 1997, p. 592-597). This was the average finding in a group of 1,092 patients. The study also showed a decrease in mortality rate of 27 percent in patients with isolated severe head injuries (Winchell & Hoyt, 1997, p 592-597).

The study was based on patients with a Glasgow Coma Score (GCS) of eight or less, a score that is typically associated with the patient being fully unconscious, or only responsive to painful stimulus such as pushing down on the patient’s sternum (breastbone). The overall conclusion of the study found that patients presenting with a GCS of eight or less in the prehospital setting, who were intubated, had a dramatic increase in survival rates (Winchell & Hoyt, 1997, p. 592-597).

 Endotracheal Intubation in Cardiac Arrest Patients
Most people when they hear the word cardiac arrest think of what they have previously seen on an episode of House or Grey’s Anatomy. Television patients seem to always survive, no matter what the case, but roughly only a quarter of people that go into cardiac arrest end up living (Nadkarni et al. 2006, p. 50-57). After Cardiopulmonary Resuscitation (CPR) is performed and the patient regains a pulse, very few survive and remain neurologically intact at hospital discharge.

A research study released in 2012 showed that patients who were ET intubated over other airway devices had a higher survival rate in the first 24 hours following cardiac arrest, as well as long term survival rates (Wang et al. 2012, p. 1061-1066). This study was conducted in 10 different major metropolitan areas throughout the United States and Canada. In the conclusion of this study they recommended that emergency medical services medical directors to consider adding intubation to their service, if not already in place (Wang et al. p. 1061-1066).

“Sudden cardiac arrest (SCA) is the leading cause of death among adults in the United States” (Carlbom et al. 2014, p. 5). The Cardiac Arrest Registry to Enhance Survival (CARES) is an online resource to help keep track of prehospital cardiac arrests, as well as hospital cardiac arrests in which CPR was performed (McMullan et al. 2013, p.617-622). Not all patients who go into cardiac arrest receive CPR, some patients have signed a POLST form with their doctors stating that if they go into cardiac arrest to not try and revive them.

This is very common in the elderly patients as well as terminally ill patients. An analysis of data from the CARES network was recently released. It showed that ET intubation was associated with a higher return of spontaneous circulation, (ROSC) than with any other airway device on the market as well as improved neurological outcome at hospital discharge (McMullan et al. 2013, p. 617-622). The study also showed that if ET intubation was not available, patients had a higher survival rate with any other advance airway on the market than with no interventions at all (McMullan et al. 2013, p. 617-622).

The Dangers of the King Laryngeal Tube Device
The King Laryngeal Tube Device often referred to as “The King” or just “King” is a blind insertion supraglottic airway device (SAD), placed into a cardiac arrest patient or an unconscious patient. The King has gained popularity over the last decade with its ease of use and the ability to place with limited training (Gaither, Matheson, Eberhardt, & Colwell, 2010, p. 368). It is placed by lifting the jaw with the thumb in the patient’s mouth and the forefinger under the jaw bone. It is then inserted into the mouth until it is at the patient’s lip level.

When first introduced to the market it was originally thought to be safer and more effective than ET intubation. A case study released in the Annals of Emergency Medicine showed that the King airway was directly linked to tongue engorgement and tongue edema (Gaither et al, 2010, p. 368). The case mentioned a 67 year old male patient who had suffered a withdrawal seizure from acute alcohol abuse and had a King airway placed by paramedics before arriving at the hospital.

Within 3 hours the patient had tongue engorgement and was progressively getting worse. After being admitted to the hospital the patient had the King airway removed and was ET intubated (Gaither et al. 2010, p. 368). “The patient’s tongue swelling, protrusion, and color improved within minutes of Laryngeal Tube Removal (Gaither et al. 2010, p. 368).

This patient had no allergies, or autoimmune diseases so tongue engorgement could not be linked to the latex part of the King airway (Gaither et al. 2010, p. 368). In conclusion to the study, Gaither stated, “We believe compromise of venous drainage from the tongue is the most likely explanation for the patient’s lingual engorgement” (Gaither et al. 2010, p. 368).

Medical research and studies are often performed on swine (pigs) at many universities and hospitals. An article released in 2012 in the medical journal Resuscitation showed how the use of the King airway may be detrimental to patients in cardiac arrest. “Impairment of Carotid Artery Blood Flow by Supraglottic Airway use in a Swine Model of Cardiac Arrest” showed that the proper use of the King airway still caused damage to the patient in cardiac arrest (Segal et al. 2012, p.1027).

The study used nine swine models that were induced into cardiac arrest, had a King Airway placed and then had CPR performed on them. In each pig, blood flow pressures were measured in the aortic, right atrial, the common carotid and intracranial areas. “Results from this study in pigs suggests that there may be unanticipated consequences of using SAD’s in the management of patients in low-flow states such as cardiac arrest” (Segal et al. 2010, p. 1027).

This was an important finding since the King airway had up to this point been considered to have limited effect on the neurological outcome of patients. The study concluded with, “In pigs undergoing CPR, use of SAD originally designed for human use was associated with a significant reduction in carotid blood flow when compared with an endotracheal tube” (Segal et al. 2010, p. 1027).

Improving Endotracheal Intubation Success
Endotracheal intubation is a skill that takes many hours to master and can prove difficult for the inexperienced paramedic, but there are assist devices that can help. A device known as the gum-elastic bougie can help novice and inexperienced paramedics perform endotracheal intubation with ease. It is a 70 centimeter long, semi ridged guide wire coated in rubber, and it helps facilitate intubation. Slightly bent at one end, it is used by viewing the vocal cords and passing through them into the trachea. Once in the trachea an endotracheal tube can then slide over the gum-elastic bougie and proceed into the trachea.

Many providers see this as a crutch, but there are several flight medic agencies that requires its use in all intubations. Dogra, Falconer and Latto stated, “One of the simple aids to unexpected intubation is the gum-elastic bougie. We recommend that all trainees at an early stage in their career be taught how to use the gum-elastic bougie” (Dogra, Falconer, & Latto 1990, p. 775). Referencing that study “Successful Difficult Intubation,” it was shown that there was a 100 percent success rate when using the gum-elastic bougie properly during intubation. (Dogra et al, 1990, p. 775)

Another device gaining popularity in endotracheal intubation assist, is the video assist laryngoscope. Called indirect laryngoscope by medical personnel, “they relay the image from a distal camera” (Popat, 2009, p. 146). These devices are either attached to a cord that runs to a monitor or have a battery powered camera on the laryngoscope handle. When the healthcare provider prepares to intubate they do not actually have to look into the patient’s mouth, they pass the tube through the mouth and watch it go into the trachea on the live video feed (Popat, 2009, p. 146).

This device has been used in emergency rooms for nearly a decade and is gaining popularity on the ambulance as well (Popat, 2009, p. 146). The likelihood of not being able to intubate a patient with this device is low. Despite its effectiveness for ET intubation success, cost is a major barrier to widespread use in the field.

 Opposing Views
There are opposing views to endotracheal intubation in the pre-hospital setting. Some medical personnel believe it takes too much time to successfully do, or that it cannot be properly taught in paramedic school in such a short time. Although these are very good points, endotracheal intubation has been shown to be the best emergent airway in the back of an ambulance.

Most emergency medical services carry both the endotracheal tube and the King. The King airway is often seen as a backup for paramedics if intubation is unsuccessful. The 2 main points that favor the King airway are; the ability to use it quickly, and also the ability for individuals to learn how to properly use it in a short timeframe.

Opposing views of endotracheal intubation typically come from accidental esophagus intubations. 3 things can be used to help prevent esophagus intubations are clinical assessment, oesophageal detection devices, and carbon dioxide detectors (Perkins, Nolan, & Soar, 2012, pg. 34). The clinical assessment consists of listening for breath sounds over the lungs, and seeing mist in the endotracheal tube after intubation.

Oesophageal detection devices are objects that work on the basis of pressure; they are placed on the endotracheal tube and pulled back. It looks like a large syringe; if it pulls back with resistance the endotracheal tube is in the esophagus, if it is pulled back without resistance it is in the trachea.

Carbon dioxide detectors come in various forms, but they all accomplish the same thing. They are placed on the endotracheal tube and measure any detectible amount of carbon dioxide coming through the tube. If there is carbon dioxide present, it means the tube is correctly placed in the trachea; if there is none present, the tube is in the esophagus.

Using these techniques can let the provider know that the tube is in the right place, and air is getting delivered to the patient’s lungs, with the preferred method being end tidal carbon dioxide (Perkins et al. 2012, pg. 34).

Training Time
One of the major drawbacks to endotracheal intubation is the time it takes to learn how to perform. A skill done by physicians since the early 1900’s only became part of emergency medical services in the late 1970’s. Prior to then, there was no classification of paramedics on ambulances, only emergency medical technicians and first aid technicians. Seeing a need for advanced medicine in the pre-hospital setting, the paramedic was created in the early 1970’s.

A paramedic course takes roughly 2 years to complete, which doesn’t yield enough time to learn intubation. The King airway is taught in EMT and paramedic school along with several other basic airways. It has been shown that only 2 hours of training is needed to learn how to be competent in the use of the King airway (Franscone et al. 2011, p. 1534). Initial ETI training is between 17 and 32 hours, with between 6 and 10 ETI placements attempted during that time (Franscone et al. 2011, p. 1534). The King airway is a valid choice for emergency medical services that do not employ paramedics.

 No Need for a Backup Device
A pilot study of the King airway in rural Iowa gave some insight on the use of supraglottic airways. In 2008 Russi, Hartley, and Buresh showed that using the King airway first in cardiac arrest patients that there was no need for a backup. This study took place over 12 months with a total of 13 patients with a mean age of 60.7 years old (Russi, Hartley & Buresh, 2008, p. 135). It concluded, “All patients had cardiopulmonary or traumatic arrest. The King was successfully placed on the first attempt in all but one case” (Russi et al, 2008, p. 135). They contribute the one failure to the patient having jagged teeth. Upon second attempt the King airway was placed properly (Russi et al, 2008, p. 135).

This information shows the effectiveness in regards to placement of the King airway, but does not state the long-term patient outcomes. For an ambulance staffed with paramedics, having a King airway stocked can prove useful if intubation is unsuccessful. In these cases the King airway is then seen as the backup device to the endotracheal tube. In concluding their study, “Although this pilot project is small, it emphasizes the need for additional rapid airway management adjuncts given the number of ETI failures” (Russi et al, 2008, p. 138).

The Few Pitfalls of Endotracheal Intubation
With any medical device there are some drawbacks to endotracheal intubation. From a study published in 1980, there are a few pitfalls to be discussed. The overview was done by 3 doctors conducted on 150 adult patients. Their study showed “excessive cuff pressure to achieve seal of the airway was the most common problem during endotracheal intubation (19 percent)” (Stauffer, Olson, & Petty, 1980, p. 66). Since then, larger cuffs have been placed on the endotracheal tube. Currently the cuffs on the endotracheal tubes hold 10 mL of air, about three-quarters the size of a golf ball. This is enough to hold the tube in place in the trachea but does not cut back on carotid blood flow to the brain.

One other point observed was the ability of patients to self-extubate; this occurred in 13 percent of patients (Stauffer et al, 1980, p. 66). The ability to self-extubate is due to the patient becoming increasingly conscious and then being able to pull out their endotracheal tube. The 2 previously-talked about faults about the endotracheal tube prove to be minor and have been improved, or are not comparable to the endotracheal tube itself.

 If All Else Fails
There is 1 final option that can be used in the pre-hospital setting if the endotracheal tube and King Airway are unable to be placed. For patients 8 years and older it is called surgical cricothrotomy, and for patients younger there is needle jet insufflation. These are both used if airway management cannot be completed by accessing the trachea through the patient’s mouth.

The adult version is an infield surgical procedure, where an incision is made vertically just below the Adams apple, then a horizontal cut or puncture is made in the cricothyroid membrane. Once this opening is made the endotracheal tube is placed in the opening into the trachea, and respiration for the patient can begin.

The King Airway cannot be used in this technique due to its size. The needle jet insufflation procedure is done by inserting a needle into the cricothyroid membrane. Once the needle is in the trachea, oxygen can be delivered through the needle forcefully with the use of a bag valve device.

As one can see from the proceeding paragraphs, it is easy to see why endotracheal intubation is still the gold standard for airway management in the pre-hospital setting. There is no doubt that it is a difficult procedure to learn, but with training and adjunct assistant devices, it becomes a very doable procedure in the field. With that being said, there still is a place for the King airway device; for ambulance services without paramedics it is a valid option for airway management. It is also a good backup for endotracheal intubation if unforeseen events make intubation not plausible. Commitment towards training will be the key to keeping endotracheal intubation in the pre hospital setting an option for emergency airway management.



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