Simple lessons to guide oxygenation and ventilation
By COREY M. SLOVIS, MD, FACP, FACEP and KEVIN HIGH, RN, MPH, EMT
Nothing can be done to reverse hypoxic brain damage once it occurs. Because of this fact, maintaining an airway and ensuring adequate oxygenation supersedes everything other than scene safety. Each of us must have a well-planned algorithm to deal with both expected and unexpected problems we face when trying to stabilize a patient's airway. Similarly, once we've mastered the basic techniques of airway maintenance and ventilation, we should continue to stay current by learning newer concepts and treatments. The following "commandments" formalize a set of principles for airway management.
PHOTO COURTNEY McCAIN
Oxygenation and ventilation are the top priorities. There's an old medical adage that remains true: “Patients do not die or suffer brain damage because you cannot, or do not, intubate them; they die or suffer brain damage because you cannot, or do not, oxygenate and ventilate them.”
Care must center on oxygenation and ventilation. Becoming overly focused and developing tunnel vision during intubation attempts can ultimately lead to a disastrous end. Remember, the No. 1 priority is to oxygenate and ventilate the patient, not to place a device or perform a skill.1,2
Airway management does not mean intubation. Airway management means just that — managing the patient's airway to ensure patency, provide adequate ventilation and maintain appropriate oxygenation. This should be done in the most prudent and expeditious way available.
Many times we focus on using advanced measures or procedures, forgetting that they're often useless, and perhaps detrimental, without the basics. Merely performing a chin lift or jaw thrust can open and/or salvage many airways. The proper use of basic airway adjuncts, such as oral and nasal airways, can convert a difficult-to-ventilate patient into a stable, well-ventilated one.
The appropriate administration of high-flow oxygen is enormously beneficial. However, patients in extremis continue to be treated with low-flow oxygen or have ventilation attempted with improperly sized or fitted masks. Even worse, some hypoxic patients receive no oxygen therapy at all while their caregivers try multiple medications rather than simply providing oxygen.
Understanding proper oxygen administration and the rationale behind it are paramount. We must never forget that airway management is a collection of skills and techniques, not just an attempt to place a tube or another device into the patient's mouth or trachea.3
Be an expert at bag-valve-mask (BVM) ventilation. BVM ventilation is the most underrated — and perhaps most undermastered — EMS skill. Using properly fitting masks, using the correct size bag for your patient (an adult, a child or a neonate) and employing excellent technique are all imperative to good patient care. Proper technique involves lifting the mandible upward and using an oral airway (and/or a nasal airway) as an adjunct during BVM ventilation. Paying attention to the basics of this skill will make it maximally effective.4
Beware of using high bag volumes and pressures; both can cause gastric distention and increase the risk of regurgitation. The use of a nasogastric or an orogastric tube to decompress the stomach is optimal for the infant or child. Your system should consider use of nasogastric and orogastric tubes as airway adjuncts in the mask ventilation of pediatric patients.
Take advantage of clinical time in the operating room or any other opportunities you have to learn and master proper bagging techniques. Practice this skill, remembering that consistent airway basics are usually more helpful than occasional airway brilliance.
Finally, it's important to remember that two or three are better than one when it comes to BVM ventilation. Too many EMS providers feel embarrassed when they can't successfully bag a patient and prefer to let ineffective ventilations continue rather than ask for help.
A two- or three-person technique — with one provider maintaining a good mask seal, another provider bagging and a potential third individual providing cricoid pressure — is almost always more effective than one person trying to bag, maintain a good seal and not provide cricoid pressure.
Know your equipment. Becoming an expert in BVM ventilation starts with knowing your equipment. Does your bag have a reservoir? Where's the pop-off valve? What special features does your bag have?
That daily check sheet is there for a reason. You must regularly check and maintain your airway supplies and equipment. Airway equipment is arguably the most important thing you carry, so why not maintain and check it every shift? Be vigilant. A good provider leaves nothing to chance.
Having backups (e.g., laryngoscope blades, bulbs and handles) and the ability to troubleshoot equipment are also important. To enhance your knowledge base, read the product inserts that accompany BVMs, airways and endotracheal (ET) tubes. Manufacturers also provide a lot of information on their Web sites and in other publications.
No new piece of equipment should be introduced into your system without proper training and follow-up. Know all your airway management equipment, and assume personal responsibility for its proper functioning.
Suctioning is often best accomplished with three providers rather than two.
Know at least one rescue ventilation technique. Rescue ventilation can best be described as a ventilation attempt or technique to use in the face of a failed airway — a technique to use in the "can't-intubate/can't-ventilate" scenario.
The most basic rescue technique is two-person BVM ventilation. It should be tried immediately when you have difficulty ventilating a patient.
If multi-person ventilation isn't effective, at least two techniques should be considered — use of a blind insertion device, such as the CombiTube or King LT-D Airway, and use of the Laryngeal Mask Airway (LMA). These devices are easy to use, can be inserted quickly and safely, and can accomplish ventilation when previous airway attempts fail.5,6
The CombiTube allows for blind insertion in the most difficult of patients and situations and provides some protection against aspiration and higher airway pressures. Inexpensive, easy to learn and simple to master, the CombiTube or another blind insertion device should be in every provider's arsenal of equipment.
The LMA has found its way into the prehospital and emergency department (ED) settings. Its use as a rescue device has been well documented. It forms a seal around the laryngeal inlet and provides a pathway to ventilate the patient and some protection against aspiration. The ability to blindly insert this device and rapidly and effectively ventilate most patients makes it a great prehospital tool for difficult airways.
|Every provider should know at least one rescue ventilation technique. Four are pictured below. The LMA (A & B), CombiTube (C) and King LT-D Airway (D) are easy to use and allow for ventilation in patients with difficult airways in less than 20 seconds.|
PHOTOS RICHARD LESCALLETTE
Few skills are as fast, low-tech and efficacious as these. The LMA and CombiTube can be used to provide ventilation in less than 20 seconds in the hands of airway experts. Similarly, medical personnel with no previous airway skills and a brief manikin demonstration of the devices could effectively provide ventilation with either device in less than 45 seconds. Speed, success and low complication rates make these rescue ventilation techniques the best choices in the prehospital or emergency setting.
Develop a personal airway algorithm. Each provider should have an algorithm specific to their skill level and approved scope of practice. Not all patients and situations you encounter are going to be the same. Therefore, having only one or two skills in your repertoire constitutes a potentially dangerous, one-size-fits-all approach to airway management.
Everyone's algorithm should begin with the basics — sort of a "plain vanilla" approach. The basics taught in an American Heart Association Basic CPR course work great; begin there and then enhance your skills in a step-wise approach. Your algorithm should proceed from basic, less-invasive maneuvers to more advanced and potentially invasive techniques as indicated. Example: Start with BVM ventilation; advance to ET intubation; then place a blind esophageal device or use an LMA; and, finally, perform a needle cricothyrotomy.
Each provider must have a plan for a patient they can't intubate or ventilate. A can't-intubate/can't-ventilate scenario is a nightmare. When faced with a critically ill patient, each of us must have a carefully thought-out, step-by-step plan — one that was calmly devised and practiced, not one thought up at the spur of the moment in the middle of a panicked and potentially fatal situation.
Don't let your ego get in the way. Hubris (exaggerated pride) can be dangerous for your patient, your partner or colleagues, and your career. Remember, your goal is proper patient care and a good outcome, not skill accumulation or personal success. The "Rule of 2" is a good one to live by: If you're unsuccessful at a skill, give your partner a chance after you've failed twice.
Similarly, if you're unsure about how or when to perform a skill, ask for assistance. Teamwork in EMS is essential, so don't be embarrassed about asking for help. Just be thankful when it arrives. Do the right thing, and don't let your pride get in the way.
Invest time in learning airway skills. We all have a finite amount of time that we can use to keep our skills updated. Regularly devote training and practice time to airway management. Practice is important because, as time goes by, we often lose some of the finer points of airway management.
Try to not limit yourself to manikins. Work on gaining access to a local operating room or ED to practice and expand your skills. Contact the attending anesthesiologist or ED director, and explain your needs and goals. Many physicians and certified registered nurse anesthetists are happy to have someone accompany them for a day. During your time with these airway professionals, view airway anatomy and work on improving your BVM ventilation techniques in this controlled, well-lit environment.
Another way to maintain your airway skills is to read about the latest techniques and advances in airway management.7 The Internet is a great place to start. Here are a few well-organized and informative sites:
Finally, if the above venues are unavailable or don't meet your specific needs, you can attend a major EMS conference. Many sessions focus on advanced airway management and several offer hands-on training with simulators or cadavers.
Use an end-tidal CO2 (EtCO2) detector and/or esophageal detector device to confirm every intubation. For many years, the proper placement of an ET tube was thought to be best confirmed via the physical exam. The gold standard for confirming correct ET tube placement was thought to be observing the tube passing through the vocal cords, determining the presence of breath sounds over the chest, condensation in the ET tube and absence of breath sounds over the epigastrium. However, even with confirmation by all these signs, some patients are still esophageally intubated.8
Relying solely on a physical exam for ET tube confirmation is risking up to a 10% chance that the tube is in the wrong location. The physical exam is notoriously inaccurate and should not, by itself, be used to confirm ET tube placement.
If anesthesia personnel are required to use EtCO2 devices for patients they intubate, we should be required to use a confirmatory device, too. Remember that patients in the OR usually haven't eaten for six to 12 hours, have been evaluated with a full history and physical exam before the intubation and are intubated in a calm, quiet, well-lit operating room. Our patients, however, have to be intubated in the worst of conditions and are usually encountered with food in their stomach or blood or emesis in their mouths. Prehospital intubations are usually performed in uncontrolled settings, such as on the side of the road, or in poorly lit environments, including the inside of partially collapsed vehicles. Therefore, it's appropriate that we are required to use the same aids to confirm an intubation as the certified airway experts do. It's shocking to see published rates for unrecognized esophageal intubations by EMS providers as high as one in four when EtCO2 detectors aren't used.9
Another quick and easy way to confirm ET tube placement is with an esophageal detector device (EDD), which uses a syringe or bulb in an attempt to aspirate air from the trachea or esophagus.10 The rigid, cartilaginous trachea won't collapse around an ET tube, thus allowing the EDD to aspirate fully. If the tube is improperly placed in the esophagus, the soft tissue of the esophageal wall will collapse around the end of the tube, and little or no air can be aspirated by the EDD.
EDDs can be used in conjunction with the EtCO2 and should be mandatory in pulseless patients who don't have any detectable expired CO2. These devices are inexpensive, fast and simple to use. The use of one or both should be considered a standard of care for all intubations performed in any emergency setting.
When seconds count, don't count on seconds. Each airway maneuver or intubation attempt should be your best effort. Often, our best chance at getting a patient intubated or an airway placed is the first attempt. Maximize your chances by leaving nothing to chance. Carefully pre-oxygenate and appropriately position the patient, correctly position yourself, and then perform the procedure. Don't give a second-best effort to any airway management skill.
Each maneuver or attempt at airway management should be the clinician's best effort, using optimal skills and judgment. Taking an extra few seconds to verify that everything is optimally positioned and prepared for the existing conditions often means the difference between success and failure.
Excellent clinicians have a solid knowledge base and use sound principles to guide their practice. Most of us work in dynamic and, at times, uncontrolled settings. To succeed, you must follow some established guidelines. As you grow in your chosen career, also continue to improve your airway knowledge and strive to follow these commandments. Hopefully, they'll empower you to maximize your skills, expand your knowledge base and enhance your problem-solving abilities.
Corey M. Slovis, MD, FACP, FACEP, is professor and chair of the Department of Emergency Medicine at Vanderbilt University Medical Center, Nashville, Tenn., and serves as the medical director for Nashville Fire EMS. Slovis is also a member of the EMS1 editorial board. Throughout the 1980s, he served as medical director for the Grady Hospital EMS program and as the fire surgeon for the city of Atlanta.
Kevin High, RN, MPH, EMT is a flight nurse with Vanderbilt LifeFlight, Vanderbilt Medical Center, Nashville, Tenn. He began his career in EMS in the early 1980s. In 2003 he was chosen by the Association of Air Medical Services as Flight Nurse of the Year, and he is active in the air medical community.
- Wrenn K, Slovis C: "The ten commandments of emergency medicine." Annals of Emergency Medicine. 20:1146-1147, 1991.
- Stewart C: "Airway management with rapid sequence intubation (RSI)" parts I and II. Emergency Medical Services Magazine. 34(1):31: 31, 1999, and 34(3):52, 1999.
- Airway Management: Principles and Practice. Edited by Jonathan L. Benumor (Ed.). Mosby: St. Louis, 1996.
- Levitan RM: "Patient safety in emergency airway management and rapid sequence intubation: Metaphorical lessons from skydiving." Annals of Emergency Medicine. 42:81-87, 2003
- Pollack CV: "The Laryngeal Mask Airway: A comprehensive review for the emergency physician." Journal of Emergency Medicine. 20:53-66, 2001.
- Agro F, Frass M, Benumof JL, et al: "Current status of the CombiTube: A review of the literature." Journal of Clinical Anesthesia. 14:307-314, 2002.
- Kovacs G, Bullock G, Ackroyd-Stolarz S, et al: "A randomized controlled trial on the effect of educational interventions in promoting airway management skill maintenance." Annals of Emergency Medicine. 36:301-309, 2000.
- White SJ, Slovis CM: "Inadvertent esophageal intubation in the field: Reliance on a fool's 'gold standard' (editorial)." Academic Emergency Medicine. 4:89-91, 1997.
- Katz SH, Falk JL: "Misplaced endotracheal tubes by paramedics in an urban emergency medical services system." Annals of Emergency Medicine. 37:62-64, 2001.
- Bozeman WP, Hexter D, Liang HK, et al: "Esophageal detector device versus detection of end-tidal carbon dioxide level in emergency intubations." Annals of Emergency Medicine. 27:595-599, 1996.
Rule of Twos
By Darren Braude, MD, EMT-P and Kathy Kaestner, MA, EMT-P
Rule of Twos
- 2 people: One to ventilate, one to hold the mask
- 2 airways: NPA + OPA
- 2 fingers: For cricoid pressure
- 2 inches: Head elevation to sniffing position
- 2 seconds: Slow, gentle ventilation
- 2 PSI: Pounds per square inch = minimum pressures
Bag-valve-mask (BVM) ventilation is one of the most important EMS skills, but it's notoriously difficult to teach and perform. The Rule of Twos that we teach in our airway program can assist students and instructors alike. This strategy helps EMS providers remember optimal BVM technique for adults and older children.
Optimal technique may not be necessary with all patients. However, it's what you need to fall back on when things aren't going well. It should be noted that, despite optimal BVM technique, a few patients still can't be adequately ventilated. In these difficult situations, insert an LMA, a CombiTube or another rescue device.
PHOTO DARREN BRAUDE
Optimal BVM ventilation using the Rule of Twos on a medical patient for whom spinal precautions weren't indicated: Note the two-person technique to maintain the mask seal and ventilate the patient, with head elevation to the sniffing position, and cricoid pressure (by a third provider). Both an NPA and OPA of appropriate sizes are placed, although not visualized. Ventilation is slow and gentle using minimum pressures. The BVM is connected to high-flow oxygen.
The hardest part of performing BVM ventilation for most providers is achieving an adequate seal between the mask and the patient's face. Although the wrong size mask, facial trauma, facial hair and blood, emesis or secretions may impair the seal, the most common problem is technique. It's much easier to achieve and maintain a seal using a two-person technique. This component is, therefore, the first point of the Rule of Twos — one to ventilate, one to hold the mask.
The two-person technique is simple. One provider holds the mask with two hands (to provide a better seal), while the other provider slowly and gently ventilates the patient. The provider holding the mask is also responsible for maintaining the airway and spinal precautions, if indicated. A jaw-thrust maneuver (i.e., lifting the jaw toward the mask rather than vice versa) works well for maintaining the airway and can be combined with patient head-tilt if not contraindicated by potential cervical spine trauma.
Airway adjuncts, such as nasopharyngeal airways (NPA) and oropharyngeal airways (OPA), are often forgotten in the midst of a chaotic scene with a critical patient, but these simple devices can make a lifesaving difference. The second point of the Rule of Twos (NPA + OPA) reminds us that the use of two airway adjuncts is beneficial when you're having difficulty ventilating a patient.
An OPA and an NPA may be used together, and two NPAs can be used along with an OPA, if necessary. It's critical to ensure these devices are appropriately sized for each patient; a device that's too large or too small may actually impair ventilation.
Air, like water, will take the path of least resistance. To maintain optimal airflow into the lungs, resistance in the airway must be minimized and resistance in the esophagus maximized. Resistance in the upper esophagus is increased by using cricoid pressure, also known as Sellick's maneuver. The third point in the Rule of Twos is, therefore, the use of two fingers to perform cricoid pressure.
The cricoid ring, the only complete ring in the trachea, is located below the more obvious laryngeal cartilage. Pressure on the front of this ring will be transmitted to its back. The esophagus is then compressed between the back of the cricoid ring and the spinal column. It's important to apply firm pressure but not so much that the ring is misshapen; this may occlude the airway in small patients. Also, in the event of vomiting, cricoid pressure must be released to prevent esophageal rupture. Note: Application of cricoid pressure along with two-person BVM ventilation will require a third person.
Remember, cricoid pressure applied during intubation may actually impair the intubator's view of the larynx. Therefore, it's critical that cricoid pressure be released if you're having difficulty visualizing the vocal cords. If you continue to have trouble with visualization, perform external laryngeal manipulation.
ILLUSTRATION SHAYNE DAVIDSON
The sniffing position is achieved by extending the head (A) while simultaneously flexing the neck (B). Neck flexion is maintained by placing a few inches of padding behind the head. This position is optimal for both bag-valve-mask ventilation and endotracheal intubation.
As mentioned, minimizing airway resistance is one of the important goals of optimal BVM ventilation. The sniffing position is the best position to minimize airway resistance during BVM ventilation, and also happens to be the best position in which you can visualize the larynx during intubation (see Figure 1). The combination of forward flexion and extension of the neck is achieved by elevating the head at least two inches, which is the fourth point of the rule of twos.
Elevating the head can also assist with difficult intubations and can be increased with additional padding, if needed. This position is, obviously, contraindicated in the patient with suspected cervical spine trauma, which adds to the difficulty of adequately ventilating and intubating such patients.
The fifth point of the Rule of Twos reminds the provider to deliver a slow, gentle ventilation over two seconds, rather than faster ventilation. Slower ventilations result in more air going into the lungs than the stomach, a goal of optimal BVM ventilation.
Slow ventilation also prevents pressure damage to the lungs (i.e., barotrauma) and is the technique emphasized by the American Heart Association. The AHA uses the “squeeze-release-release” technique to stress this same point.
It's also important to allow sufficient time for exhalation, particularly if the patient has bronchospasm or another condition that impairs the flow of air out of the lungs.
Many EMS providers are misinformed when it comes to ventilation and left with the impression that more is better. Overly aggressive ventilation results in more air entering the stomach, which may eventually impair diaphragmatic movement and subsequent ventilation. It also predisposes the patient to vomiting with subsequent aspiration and can lead to lung damage as well as impaired venous blood return to the heart.
The lowest possible pressures and tidal volumes that create adequate ventilation should be used to prevent these complications. To emphasize this, the last point of the Rule of Twos is two PSI. Note: This is not the actual pressure being used, but a useful reminder to minimize these pressures.
Assess for adequate ventilation by observing minimal chest rise or hearing appropriate lung sounds. In the past few years, target tidal volumes have dropped from the recommended 10–15 cc/kg of a few years ago to 6–10 cc/kg. This change means that a 70 kg adult should receive about 550 cc per breath (8 cc/kg), or approximately one-half of a standard adult self-inflating bag.
For many rescuers, using one hand to squeeze the bag rather than two will help avoid over-ventilation.
Darren Braude, MD, EMT-P, serves as the medical director for the EMS Academy, Lifeguard Air Emergency Services and Emergency Airway Training Program. He is also an assistant professor of emergency medicine at the University of New Mexico. Contact him via e-mail at email@example.com.
Kathy Kaestner, MA, EMT-P, is an instructor at the EMS Academy and affiliated with the University of New Mexico.