AIRWAY, VENTILATION, AND OXYGENATION
IMPORTANT CONCEPTS IN AIRWAY MANAGEMENT
The assessment and management of a patient’s airway is the crucial initial priority in all circumstances. Usually, this is easily accomplished when faced with a talking, breathing, and coherent patient. Other times it is more difficult to determine if the patient’s airway is compromised, ventilatory rate inadequate, or air exchange is poor. Additionally, there may be circumstances when airway adequacy may become rapidly compromised secondary to a disease or injury (i.e., thermal injury to the face or anaphylaxis). When these conditions exist, an airway management approach must be determined rapidly and early airway management must be considered a priority.
The purpose of establishing an adequate airway (or protecting an airway from compromise) is to allow appropriate movement of air to maintain oxygenation and to facilitate elimination of CO2. There is a significant risk of hypoventilation and hypoxia with any airway intervention. This risk is often overlooked in the “heat of the battle.” Sometimes, during the actual procedure, healthcare providers lose sight of the need for basic airway and ventilatory management. As procedural attempts continue, the patient’s oxygenation status drastically decreases and their CO2 dramatically rises. Both of these conditions are associated with significant potential to worsen patient outcome. The practice of pre-oxygenating a patient (creating an oxygen reseviour by nitrogen wash-out) before DAI is specifically to minimize the hypoxia associated with airway procedures.
Hypoxia has been shown to decrease survival from pre-hospital trauma, especially in head injury. Similarly, increases in CO2 as a result of little or no ventilation (for example, during the time an advanced airway is being attempted) also decreases survival and worsens outcome in head injury patients. If the process of establishing an airway is prolonged (as much as 30 seconds), we may actually make the patient’s outcome worse, even though the airway is established. If attempts at advanced airway placement are difficult or prolonged, an assessment of the adequacy of BLS airway management must be made. It is better to maintain a BLS airway than make repeated or prolonged attempts to establish an advanced airway. All Providers on scene should be aware of periods of no ventilation (during airway management, transport or other circumstances) and make an effort to correct the situation immediately. In patients that can be ventilated effectively with a BVM, advanced airway attempts should be limited to two (2) in the non-arrested patient. The decision to intubate a patient must ALWAYS be focused on the needs of the patient, availability of equipment, skill of the intubating Provider and possible use of more advanced tools or experienced Providers that are en route to successfully intubate with the fewest number of attempts possible. Repeated unsuccessful attempts to intubate a patient that can be effectively ventilated are harmful. The use or deference of a “Patients” second or third intubation attempt is not a question of pride or failed ability. It is the patient that potentially suffers. It is acceptable (and in many cases expected) for all responders to defer the 2nd or 3rd Intubation attempt to a more experienced Provider as we work as a team to secure the airway.
AIRWAY MANAGEMENT APPROACH
Our approach to airway management is extremely important. The best decision on how to manage an airway can be reached by answering the following questions:
• Is the airway being adequately maintained?
• Is there a need to clear the airway?
• Is the airway being protected against aspiration?
• Is ventilation adequate?
• Is oxygenation adequate?
• Is there a condition present, or is there a therapy required that mandates airway adjuncts?
• Do I have the tools to correct this problem?
• Do I have the skills to correct this problem?
Airway procedures should be implemented starting with the least and progressing to the most invasive:
• Manual maneuver (chin lift, jaw thrust, etc.),
• BLS adjuncts (NPA, OPA),
• Cardiac Arrest airway (King LTS-D),
• Orotracheal intubation,
• Rescue airway (LMA Supreme, King LTS-D),
• Surgical / needle cricothyrotomy
If the patient’s airway cannot be maintained (i.e., inadequate ventilation), the Provider should immediately consider airway maneuvers (within their scope of practice) as listed above. If unable to establish an advanced airway, return to BLS maneuvers while evaluating the need for a rescue airway. If still unable to maintain adequate ventilation and/or airway protection, proceed to placement of the LMA, King LTS-D or other rescue airway. If STILL unable to ventilate, and the patient would be unlikely to survive, proceed to needle cricothyrotomy for the pediatric patient (10 years of age or less) or surgical cricothyrotomy (over 10 years old).
COMMON SENSE APPROACH TO FACILITATE DIFFICULT AIRWAY MANAGEMENT
• Audibly verbalize the procedure as it is being done (by intubating provider)
• Airway Axis Alignment by head repositioning (occipital / shoulder padding, “ramping”, sniffing)
• Consider laryngeal manipulation,
• Change your position,
• Change the blade,
• Change the provider who is intubating (this is often overlooked as a significantly useful approach)
• Re-evaluate the need for an advanced airway versus expedited transport of patient to definitive care
with BLS airway management
• Once the airway is established, secure it with tube holder
CONFIRMING AND MONITORING APPROPRIATE ADVANCED AIRWAY PLACEMENT
Once an advanced airway is placed, it is crucial that all efforts are made to ensure it is definitively placed. All advanced airway placements must be confirmed by ETCO2 capnography. Additionally, it is important to continuously monitor airway placement for changes related to movement or obstruction. It is essential that all advanced airway attempts, as well as confirmation of placement, be documented in the Patient Care Record (PCR) with copies of all monitoring equipment printouts (O2 saturation and ETCO2) when available.
Confirmation of an appropriately placed advanced airway is multi-faceted and should include:
• Visualizing the placement,
• Auscultating for breath sounds over both lungs and epigastrium,
• Observing for equal chest rise and fall,
• Monitoring ETCO2 (capnography),
• Monitoring pulse oximetry,
• Monitoring changes in vital signs, especially skin color
Once an advanced airway has been established, management of the tube or catheter should be of the
highest priority during any patient movement.
• An appropriately sized cervical collar should be applied immediately following successful placement
and securing of the airway.
• If patient is to be transported, they should be placed on a backboard and secured.
The only exception would be patients who cannot tolerate a supine position (i.e. awake
patient in respiratory distress, patient with pulmonary edema, etc.)
• The BVM is to be disconnected from the tube during any transitional movement including
Log-rolling patient onto a backboard
Moving patient onto a stretcher
Loading and unloading from ambulance or helicopter
Transfer to the hospital stretcher
The tube is to be reassessed following any patient movement
Appropriate demonstration of persistent ETCO2 is the most reliable indicator of tube placement in our assessment toolbox. All advanced airway placement must be confirmed by ETCO2 capnography. Additionally, it is important to continuously monitor tube placement for any changes related to movement or obstruction. Loss of ETCO2 is an immediate indicator of significant change, whether it is loss of tube placement or loss of perfusion. ALL changes in ETCO2 must be immediately evaluated to determine the reason for change.
VENTILATION / OXYGENATION – ADEQUATE / APPROPRIATE
After it has been confirmed that the patient has a patent airway, the next step is to assess ventilation and oxygenation status. An initial assessment of respiratory rate and depth, skin color, and mental status will give a quick picture of whether the patient is breathing and oxygenating adequately. Your physical assessment, ETCO2 monitoring, and pulse oximetry provide a very accurate picture of how well the patient is being ventilated and oxygenated. It is crucial that all Providers take responsibility for assessing adequate oxygenation and ventilation in every patient.
This can be accomplished by monitoring:
• Respiratory rate and depth,
• Skin color,
• Capillary refill,
• Lung sounds,
• Work of breathing,
• Patient position (i.e. Tripod),
• Ability (inability) to maintain secretions,
• Pulse oximetry and ETCO2 monitoring
OXYGENATION AND VENTILATION – THE IMPORTANT RELATIONSHIP
Ventilation is the mechanical aspect of breathing, in which O2 moves into the lungs and CO2 (normal byproduct of metabolism) moves out of the lungs. Proper ventilation requires both adequate tidal volume (500-600 cc for an adult male) and respiratory rate. Oxygenation is defined as “the addition of oxygen to any system, including the human body. ”With ventilation serving as the mechanical means of adding oxygen to the body, the patient must have sufficient oxygen available, and the ability for that oxygen to be utilized (O2/CO2 exchange). While ventilatory rate and depth are the key components, there are other factors that can affect whether or not the patient is being adequately oxygenated. Even if ventilation rate and depth are adequate, every patient must be evaluated for the need to have supplemental oxygen delivered and the most appropriate means for that to occur.
Considerations in determining a patient’s need for supplemental oxygen include:
• Level of consciousness
• Ventilation rate and depth
• Mental status
• Circulatory status
• Skin color
• Chief complaint
• Previous history
• Type of incident
A condition related to a patient’s breathing depth and rate that can create uncertainty for Providers is hyperventilation. Because the patient is breathing at an excessive rate and/or depth, he/she expels too much CO2. The lack of adequate CO2 causes a drop in the acid levels of arterial blood resulting in a condition called alkalosis. (Simply, the buildup of excess base in the body’s fluids) It is the alkalosis that causes many of the symptoms commonly associated with hyperventilation including anxiety, dizziness, numbness, tingling in the hands, feet, and lips, and a sense of difficulty breathing. Hyperventilation can occur as a response to serious illness or, in a healthy person, as a response to psychological stress. In either case, the key is thorough assessment to identify treatable conditions. All patients suffering from hyperventilation should be given supplemental oxygen, calm reassurance in a professional manner in an effort to normalize their respiratory rate and depth, and be offered transport to the hospital. When inadequate oxygenation is recognized, it is essential that steps be taken to immediately supplement the patient’s oxygen intake.
Remember our primary treatment goals for patients suffering from inadequate oxygenation include:
• Preventing or correcting hypoxia
• Normalizing CO2
• Minimizing the effects of secondary injuries
• Decreasing airway resistance
Once it is determined that supplemental oxygen is required, the question would be “how much?” A truly correct answer can only be reached by thoroughly evaluating your patient’s condition and considering the following guidelines:
• Nasal cannula at 2-6 L/min for patients suffering from minor injury or illnesses where lower liter flow
• Non-rebreather at 10-15 L/min (enough to keep reservoir filled) for patients presenting with altered
mental status, obvious difficulty breathing, poor skin color, poor circulatory status, possible or
confirmed CO Poisoning, etc.
• Bag-valve-mask at 15 L/min or greater (enough to keep reservoir filled) for patients with inadequate
ventilation rate and/or depth
VENTILATION RATE AND DEPTH
A common pitfall in ventilation is to over-ventilate the patient by providing too much volume or too fast a rate.
The physics that allow us to move air in and out of the lungs can also have a major impact on blood circulation (one more important inter-relationship between the ABCs). When a normally breathing patient takes in a breath, intrathoracic pressure decreases, allowing air to be “sucked in” due to the resulting pressure differential. This is in contrast to patients that are ventilated with positive pressure (whether intubated, Bag-Valve-Mask or Mouth-to-Mask). In these patients, we INCREASE intrathoracic pressure as we inflate the lungs. In this case, the heart itself is “squeezed” and doesn’t fill as well or move blood forward as well. Overly aggressive ventilation will have a dramatically adverse effect on circulation. If we don’t pay attention to rate and depth, we may actually harm the patient’s circulation, drop their blood pressure, and decrease perfusion. Ventilation depth and rate is variable and driven by the patient’s condition. We must be mindful of the volume and rate at which we are ventilating the patient. The majority of adult patients should be ventilated at a rate of 12 breaths per minute (see below). Studies have shown that excessive ventilation rates significantly decreased coronary perfusion pressures and ultimately patient survivability. This is particularly true in cases of cardiac arrest. Each ventilation should be sufficient to create adequate chest rise and be delivered over one second. In the absence of ETCO2 and pulse oximetry, rescue breathing (patients with a pulse) should be performed at the following rates
Age Group Ventilatory Rate
Neonates 40-60 bpm
Infants and Children 12-20 bpm
Adults 10-12 pbm
Today at our monthly inservice training, we were introduced to our new airway management protocols. I must say I am impressed, and excited. Many of the things that RM especially, has been advocating are outlined. ETCO2 has been required on all advanced airways, but there was a pretty good emphasis on this today.
This blog is in no way affiliated with the Lee County public safety organization. The views posted on this blog are the opinions of the authors.