BASIC REVIEW OF ENDOTRACHEAL INTUBATION FOR PROVIDERS AT A MASS CASUALTY

Abstract

Background

During a mass casualty scenario (whether manmade or natural disaster), healthcare providers could likely be overwhelmed by patients, many of whom would need airway support. In such a situation, medical personnel from a wide variety of backgrounds may be called upon to provide airway management. Such personnel could include emergency medical technicians, nurses, physician’s assistants and physicians from all specialties. In our current practice, a similar mix of medical providers are being tasked with increased airway management to support conscious sedation delivery. Increasing demand for airway management skills requires more airway training for medical personnel who may be involved in disaster medicine or other ‘out of operating room’ care.

Methods

To support the growing airway training needs for medical providers, especially in the advent of a mass casualty situation, a virtual training platform was created in collaboration with the Telemedicine and Advanced Technology Research Center, Medical Material and Research Command, US Army, the United States Army Chemical Care Casualty Division, Aberdeen Proving Grounds, MD and a consortium of universities. This project was funded by an unrestricted educational grant from Karl Storz Endoscopy America, Inc and from a grant from the Telemedicine and Advanced Technology Research Center, Medical Material Research Command, US Army.

Its goal is to gradually develop a comprehensive virtual training textbook to support personnel involved in medical disaster management and other out of operating room patient care requiring appropriate airway skills.

Results

This web-based manuscript is intended to represent the initial training module in support of the collaborative airway management training project. A mannequin-based intubation training module followed by intubation experience in the operating room are meant to complete the full instructional package. The initial training module was designed with an emphasis on graphics. The web-based format will allow this teaching material to be shared among university and government partners who need to train personnel in airway management. Continual feedback is being obtained from our partners to allow improvement and updating. The intended audience for this training would include any student learning intubation, both medical and paramedical personnel.

Conclusions

Airway training for a wide range of healthcare providers will be a growing facet of civilian and military medicine in the future. The need for such training is being driven by increasing conscious sedation procedures and the potential for manmade mass casualty situations. Military need is driven by increased healthcare at far forward combat locations. This training is designed to support continually evolving educational needs for such airway management. The initial airway training module presented here as an electronic manuscript affords the ability to continually update the information based on changing educational needs and user feedback through the collaborative efforts of participating institutions.

In the future, a full spectrum of shared, collaborative airway management training programs might be created using the proposed training paradigm.

LEARNING OBJECTIVES

1. Review airway anatomy to include how to recognize patients whose anatomy may make intubation difficult.

2. Review the basic intubation sequence to include use of standard laryngoscopes.

3. Discuss confirmation of proper endotracheal tube placement.

4. Review conditions which may pose a contraindication to tracheal intubation and airway manipulation.

INTRODUCTION

A primary goal of this project is to emphasize the value of a basic airway management training program to support disaster medicine training needs. Airway management is at the core of care for the injured patient during a mass casualty event. In addition, the requirement for emergency surgery may necessitate the use of much conscious sedation to facilitate surgical care for a large number of casualties. Many personnel other than anesthesia providers will therefore be assisting with airway management. The following review is intended to provide a basic overview of orotracheal intubation to support mass casualty airway care and out of operating room airway management training. This manuscript describes the proof of this concept and furnishes the didactic material used in this first of several training modules.

This review of basic intubation technique was prepared to support disaster medical training for the Chemical Care Casualty Branch at Aberdeen Proving Grounds, MD. The same instructional format may be useful to support civilian analgesia/sedation training.

IMPORTANCE OF AIRWAY MANAGEMENT

The vital importance of airway management is well documented in the anesthesia literature. While studying the incidence and causes of cardiac arrest due to anesthesia, Keenan and Boyan reported that failure to provide adequate ventilation was responsible for 12 of 27 cardiac arrests during the operative period.^1,2 The American Society of Anesthesiologists (ASA) closed-claims study showed that the single largest source of unfavorable outcomes during anesthesia was adverse respiratory episodes accounting for 34% of 1541 liability claims.^2,3 Seventy-five percent of the undesirable events in this closed-claims study were due to inadequate ventilation (38%), esophageal intubation (18%), and difficult tracheal intubation (17%).^2,3 Death and brain damage were outcomes in nearly 85% of the cases studied. ^2,3 Cheney et al. analyzed 300 liability claims for ventilation-related undesirable outcomes and identified airway trauma, pneumothorax, airway obstruction, aspiration, and bronchospasm as recurring patterns of management error or patterns of injury.^2,4

In the pre-hospital situation, inadequate airway management is a major contributor to morbidity and mortality.⁵ Helm et al. have reported that several studies examining pre-hospital deaths from trauma in the UK have shown that airway obstruction was thought to have contributed to death from major trauma in up to 85% of patients.^5,6,7 Other studies have shown that trauma patients may benefit from pre-hospial endotracheal intubation.⁵ In patients with multiple trauma, an overall decrease in mortality from 36 to 26% was seen when pre-hospital intubation was performed.^5,8 In patients with isolated severe traumatic brain injury, a decrease in mortality from 49% to 23% was demonstrated when pre-hospital intubation was performed. Given these data, it is clear that management of the airway is key for safe pre-hospital care and for the care of the patient with compromised respiratory status during a mass casualty event.

BASIC AIRWAY MANAGEMENT

The following basic steps are important when managing the airway of a patient. (1) A thorough airway history and physical examination must be performed. When this is not possible, as with mass casualties, point 4 becomes even more important. (2) Develop a management plan for use of a supraglottic means of ventilation (e.g. ventilation without intubation using devices such as a face mask, Combitube, laryngeal mask airway [LMA], etc.). Supraglottic airway management devices will be discussed in future training modules developed by our group. (3) A management plan for both intubation and extubation is necessary. In a mass casualty situation, many patients will require intubation due to airway loss from trauma. A number of these patients will likely undergo surgical treatment. After surgery, if the patient is extubated and is unable to tolerate extubation, it may be very difficult to reintubate them. This scenario must be seriously considered, especially in the patient whom was a difficult initial intubation. (4) An alternative plan of action should be formulated in case emergencies develop or the patient is difficult to intubate.

REVIEW OF ANATOMY

There are two openings where air can enter the upper airway. These are the nasopharynx and the oropharynx (as shown in Figure 1.) The nasopharynx begins just posterior to the internal nasal cavity and extends to the soft palate. The oropharynx begins at the soft palate and extends to the hyoid bone. The oropharynx serves as both a food and respiratory passage way. The laryngopharynx begins at the level of the hyoid bone and connects posteriorly with the esophagus and anteriorly with the larynx. The glottic opening (as shown in Figure 2) is covered by the epiglottis. The epiglottis moves freely to prevent aspiration of food from the oropharynx into the trachea. During swallowing it covers the glottic opening. During intubation, the endotracheal tube is inserted through the vocal cords into the trachea.

Figure 1.

Anatomy of the upper airway.

Figure 2.

Anatomy of the glottic opening.

PREOPERATIVE EVALUATION

Preoperative evaluations are performed on patients before receiving an anesthetic (including conscious sedation). The preoperative evaluation includes an assessment of anatomic characteristics that may make mask ventilation or intubation of the trachea difficult. Basic standards for preanesthesia care (to include preoperative evaluations) have been outlined by the American Society of Anesthesiology.^2,19 These standards would be applicable to any patient undergoing airway management including those under conscious sedation.

Preoperative Evaluation of the Upper Airway

Preoperative evaluation of the Upper Airway includes dental examination, determination of the size of the tongue versus pharyngeal size, atlanto-occipital joint extension, and anterior mandibular space (thyromental distance).²

Problems with exposure which may be seen during intubation include an anterior larynx, prominent upper incisors, large posteriorly located tongue or micrognathia (a small mandible). An anterior larynx occurs when the larynx protrudes anteriorly from the axis of the neck (as shown in label 1 on Figure 3). Prominent upper incisors are upper teeth that protrude (as shown in number 2 on Figure 3) and obstruct the oral opening. A large posteriorly located tongue (as shown in number 3 on Figure 3), is seen when the tongue is so large it allows less space in the oral cavity to visualize the glottic opening. Micrognathia decreases the relative space available to visualize the glottic opening (as shown in Figure 3).

Figure 3.

Alignment of the oro-pharyngeal axis with the axis of the trachea by optimizing the position of the head on a pillow.

Size of Tongue Versus Pharynx

The size of the tongue versus the oral cavity can be visually graded by assessing how much the pharynx is obscured by the tongue. This is the basis for the Mallampati classification of the airway (see Table 1).^9,10 Mallampati theorized that a disproportionately large tongue base could hinder exposure of the larynx. Since the tongue base cannot easily be measured directly, the size of the tongue is estimated by the Mallampati classification by noting the visibility of pharyngeal structures when the patient is observed with his mouth fully opened and the tongue fully extended. Mallampati originally proposed three oropharyngeal classes, but this was modified by Samsoon and Young to four classes as shown in the drawings below. ^9,10,20 When the entire uvula is visible (Class 1 airway-Figure 4), the laryngoscopic view is expected to be classified as Grade I (tracheal intubation by direct laryngoscopy expected to be easy) in contrast to the Class IV score where only the hard palate is seen (Figure 7), which is expected to be a technically difficult or impossible intubation.^2,9 The Mallampati class (Figures 4-7) (in isolation, as a sole method of airway evaluation) has met with only moderate success (low positive predictive value) in identifying patients who are subsequently found to have a difficult intubation.^11,12

Table 1.

Mallampati Classification

MALLAMPATI AIRWAY CLASSIFICATION SYSTEM
Class	Direct Visualization, Patient Seated	Expected Laryngoscopic View
I	Soft palate, fauces, uvula, pillars	Entire glottic opening
II	Soft palate, fauces, uvula	Posterior commissure
III	Soft palate, uvular base	Tip of epiglottis
IV	Hard palate only	No glottal structures

Modified from: Mallampati RS, Gatt SP, Gugino LD et al: A clinical sign to predict difficult tracheal intubation: A prospective study. Can Anaesth Soc J 32:429, 1985.

Figure 4.

An example of Mallampati Class I: Patient sits upright; head in neutral position; opens mouth as wide as possible; protrudes tongue; Soft palate: anterior, posterior tonsillar pillars are visible; uvula visible - all of it.

Figure 7.

An example of Mallampati Class IV: The soft palate is not visible; a difficult intubation is predicted; consider awake intubation.

Atlanto-Occipital Joint Extension

Preoperative evaluation of cervical spine mobility (atlanto-occipital joint extension) can be performed by having the patient sit with the head erect facing the examiner and then extending the joint as much as possible. Normal extension is 35 degrees. Decreases in this range of motion may be associated with difficulties in aligning the oral and laryngeal axes during intubation.⁹ (See Figure 8).

Figure 8.

Angle measuring the extension of the atlanto-occipital joint: Angle between erect and extended planes of occlusal surface of upper teeth; normal 35 degrees; limited in spondylosis, rheumatoid arthritis, cervical nerve compression, trauma.

Anterior Mandibular Space

The anterior mandibular space is evaluated by asking the patient to maximally extend the head and measuring the distance from the notch of the thyroid cartilage to the tip of the mentum (thyromental distance-see Figure 9).⁹ If the thyromental distance is less than 6 cm, the laryngeal axis will make a more acute angle with the pharyngeal axis. This will make atlanto-occipital extension more difficult and create problems in aligning the laryngeal and pharyngeal axes. This is typically encountered in patients with a receding mandible or a short neck with a large neck circumference.^2,9,13

Figure 9.

Measurement of the thyromental distance: From notch of thyroid cartilage to bony point of the chin; with head maximally extended; distance more than 6.5 cm associated with technically easy tracheal intubation.

Dental Examination

A preoperative dental examination is needed to ascertain the presence of loose teeth, dental prostheses or other dental abnormalities.⁹ Loose teeth or dental prosthesis may be dislodged during the intubation process and result in aspiration. Protruding incisors (buck teeth) may make it difficult to obtain an adequate laryngeal view during intubation.

PATIENTS WITH RECENT TRAUMA

A future training module will address airway examination with recent trauma in greater depth. In patients who have sustained a recent trauma, assessment of the stability of the cervical spine is critical. The presence of pain on movement should be determined. If this is not possible, radiographic examination may be required.² If the patient is wearing a neck brace, it will lead to a lack of extension and possible increased difficulty in visualization of the airway. The cervical brace may need to be removed to proceed with intubation²⁰. However, the head should be maintained in a neutral position with manual axial in-line stabilization by an assistant when the cervical collar is removed.²⁰ This will be discussed and illustrated in a follow-on training module in this series.

TECHNIQUE FOR OROTRACHEAL INTUBATION

Equipment needed for endotracheal intubation include: gloves, a properly sized tracheal tube with stylet, a laryngoscope, a functioning suction catheter with Yankauer tip and facilities to provide positive pressure ventilation of the lungs with oxygen.⁹ In a mass casualty field situation, anesthetic drugs to facilitate intubation will likely not be available to first responders. During a mass casualty, oxygen may be in short supply and the patient will likely need to be ventilated with air.

Preoxygenation

Preoxygenation (also known as denitrogenation) should be performed in all cases before intubation, if time permits.^2,14 Preoxygenation allows the replacement of the nitrogen volume of the lung (around 69% of the functional residual capacity [FRC] when the patient is breathing room air) with oxygen, to provide a reservoir for diffusion into the alveolar capillary blood after the onset of apnea.^2,15 Preoxygenation with 100% O₂ and spontaneous ventilation with a tight-fitting face mask for 3-5 minutes can furnish up to 10 minutes of oxygen reserve following apnea in a patient without significant cardiopulmonary disease and a normal oxygen consumption.^2,16

The most common reason for not achieving a maximum alveolar FIO₂ during preoxygenation is a loose-fitting mask, allowing the entrainment of room air.^2,14 This can be prevented by holding the mask tightly to the patient’s face, ensuring a secure seal during preoxygenation, thereby preventing entrainment of room air.

Less time-consuming methods of preoxygenation have also been described. Using a series of 4 vital capacity breaths of 100% O₂ over a 30-sec period, a high arterial PaO₂ (339 torr) can be achieved, but the time to desaturation is consistently shorter as compared to techniques of breathing 100% O for 5 min.^2,17

Another method described is “the modified vital capacity technique.” When using this technique, the patient is asked to take eight deep breaths of 100% oxygen in a 60-sec period.^2,14,18

TYPES OF LARYNGOSCOPES

All common types of laryngoscopes consist of a handle and a blade which has a light source allowing the intubator to see the larynx. There are two major types of blades used with laryngoscopes, curved (Macintosh blade) or straight (Miller blade) as shown in Figure 10.

Figure 10.

Major types of laryngoscope blades: curved (example Macintosh) and straight (example Miller). For differences in usage, see text.

Curved (Macintosh) Blade

When intubating with a curved (Macintosh) blade, the tip of the curved blade is placed into the space between the base of the tongue and the pharyngeal surface of the epiglottis (the vallecula)(see Figure 13). After the blade is inserted into the vallecula, it is then lifted with an anterior movement, away from the upper teeth. This movement is sometimes described as “lifting towards the patient’s feet”, which stretches the hypo-epiglottic ligament, thereby elevating the epiglottis and exposing the glottic opening.

Figure 13.

Laryngoscopy with curved blade: Blade tip advanced into space between base of tongue (anterior) and pharyngeal surface of epiglottis (posterior); forward / upward movement of blade, i.e. away from upper teeth; “lift toward patient’s feet”.

Straight (Miller) Blade

When using the Miller blade, the tip of the straight blade is passed beneath (posterior to) the laryngeal surface of the epiglottis (thereby “picking up” the epiglottis) (see Figure 14). Anterior movement of the blade “lifting towards the patient’s feet” and away from the upper teeth directly elevates the epiglottis and exposes the glottic opening.

Figure 14.

Laryngoscopy with straight blade: Tip advanced beneath laryngeal surface of epiglottis; forward / upward movement of blade; “lift towards patient’s feet”.

Table 2 shows the sizes and lengths of endotracheal tubes to be used for each age, as modified from references 2 and 5. An alternative method of determining the size of the endotracheal tube is to divide the age by 4 and add 4 to give the size of the tube in millimeters (internal diameter). For example, to determine the size for a 4 year old child, a 5 mm diameter tube is required (4 divided by 4 equals 1, then add 4); for an 8 year old child, a 6 mm diameter tube is required (8 divided by 4 equals 2, then add 4); for a 12 year old child, a 7 mm tube is required (12 divided by 4 equals 3, then add 4).

Table 2.

The sizes and lengths of endotracheal tubes to be used for each age as modified from references 2 and 9

Table 2 - Size and Length of Endotracheal Tubes For Intubation:
age	ET Tube Size (mm)	Distance from Lips to Mid Trachea (cm)
Premature	2.5	8
Full Term	3.0	10
1-6 mo	3.5	11
6-12 mo	4.0	12
2yr	4.5	13
4	5.0	14
6	5.5	15
8	6.5	16
10	7.0	17-18
12	7.5	18-20
14 and older	8.0-9.0	20-22

INTUBATION SEQUENCE

If intubating from an operating table, the intubator should adjust the table height so that the patient’s face is approximately at the level of the standing intubator’s xiphoid process.

Place the Patient’s Head in the “Sniffing Position”

The “sniffing position” is based on the concept of “the elderly gentleman sniffing the early morning air.” The person is standing and “pushes the head forward” while “lifting the chin up.” Note the head is vertical, or perpendicular to the ground (see Figure 11).

Figure 11.

Sniffing position: Flex head forward on a pillow to place the plane of the face on the same level as the anterior chest wall (sternum); extend the neck, or “point the chin towards the ceiling”; aligns pharyngeal and laryngeal axes.

To optimize the intubating position, the patient’s head should be elevated 8 to 10 cm with pads under the occiput and the shoulders remaining on the table. The neck is therefore lifted forward, while the head is flexed. The plane of the face is now horizontal or parallel to the ground. In obese subjects, the pillow under the head must be enlarged until the plane of the face is at the same height as the anterior chest wall.

Note, in this position, the laryngoscope blade is pulled towards the subject’s feet (i.e. downward), and not towards the ceiling as in the extension position described in many textbooks). The flexion position serves to align the pharyngeal and laryngeal axes. Next the patient’s head is extended at the atlanto-occipital joint which aligns the oral axis with the pharyngeal and laryngeal axes. This position will in most cases allow a straight line for passage of the endotracheal tube from the lips to the glottic opening (see Figure 12).

Figure 12.

Intubating position with all 3 axes aligned: Extension of head; aligns oral cavity with conjoint pharyngeal - laryngeal axis; blade can expose glottis in this position.

Insertion of Laryngoscope

The patient’s mouth can usually be opened to allow insertion of the blade by extending the patient’s head. If this does not achieve adequate mouth opening, use the right hand to place the index finger on the patient’s upper central incisors; the thumb is then placed on the lower incisors, in front of the index finger.

Holding the mouth open with the right index finger and thumb, carefully insert the blade of the laryngoscope into the mouth with the left hand, avoiding contact with the exposed teeth. Moving from the right corner of the mouth toward the midline of the mouth and pharynx, move (sweep) the tongue to the left side of the mouth and pharynx. Using the heel of the right hand on the patient’s forehead to extend the head, open the patient’s mouth further to expose the epiglottis and vocal cords by lifting up on the laryngoscope handle. Lift in the same direction as the plane of the handle, as shown by the diagram in Figures 13 & 14. Do not use the front upper teeth as a fulcrum for the laryngoscope. This will cause breakage of the teeth. Lift the laryngoscope away from the upper teeth, i.e. towards the feet.

Visualize the structures of the pharynx. Look for the epiglottis. If you do not see the epiglottis, but see only mucosal folds, the laryngoscope blade is probably in the esophagus and you will need to carefully withdraw the blade into the mouth. As you slowly withdraw, the epiglottis should come into view.

When using a curved (Macintosh) blade, the intubator positions the blade tip behind the epiglottis in the vallecula. The floor of the mouth is raised by lifting the handle of the laryngoscope. The epiglottis is elevated and it (and the vocal cords) will come into view. If using a straight (Miller) blade, the blade tip is inserted just beyond the epiglottis. The blade is then lifted towards the patient’s feet bringing the vocal cords into view.

When the vocal cords are under direct visualization, the endotracheal tube is inserted between the cords and into the trachea. As shown in Figure 15, views of the glottic opening during laryngoscopy can vary from a complete view of the vocal cords and entire glottic opening to an obstructed view of only the base of the arytenoid cartilage. These glottic views were classified by Cormack and Lehane into 4 CL views (Grade 1 - full view of the glottic opening to Grade 4 - only the soft palate is visible).¹³ The better the CL view during laryngoscopy, the easier the insertion of the endotracheal tube through the glottic opening in most patients.

Figure 15.

Classification of view obtained during direct laryngoscopy: Grade 1 - full view of glottic opening; Grade 2 - Posterior portion of glottic opening visible; Grade 3 - only tip of epiglottis visible; Grade 4 - only soft palate visible.

Reprinted with permission from Studies in Health Technology and Informatics 132 (2008);33; Boedeker BH, Berg BW, Bernhagen M, Murray WB. Direct versus Indirect Laryngoscopic Visualization in Human Endotracheal Intubation: A Tool for Virtual Anesthesia Practice and Teleanesthesiology. ©2008, with permission from IOS Press.

Insert the tube through the cords until the cuff goes out of view. We recommend using a styletted tube which is easier to maneuver in the airway (see Figure 16). After the distal tip of the endotracheal tube is inserted through the glottic opening, have an assistant remove the stylet. Then advance the tube until the cuff is approximately 1 cm past the vocal cords. Check the depth of insertion; typically the 19-21 cm marks should be at the level of the teeth. Then remove the laryngoscope carefully to prevent damage to the teeth. Firmly grasp the newly inserted endotracheal tube. Inflate the cuff on the endotracheal tube and carefully remove the stylet unless previously accomplished. Then connect the endotracheal tube to a ventilation circuit.

Figure 16.

An endotracheal tube with a stylet.

CONFIRMATION OF ENDOTRACHEAL TUBE PLACEMENT

Squeeze the ventilation bag and auscultate over all lung fields and abdomen as shown in Figure 17. The chest should rise symmetrically with each delivered breath. Breath sounds should be bilaterally equal. If you hear breath sounds only over the right side, but not over the left, the endotracheal tube is probably located in the right mainstem bronchus and needs to be pulled back a little until breath sounds are heard over the left side as well. In adults however, the tube should not be pulled back beyond 20 cm for fear of unintended extubation. It is important to listen over the stomach for evidence of unintentional esophageal intubation (see below). Confirm the presence of CO₂ with a chemical detector. Alternatively, use a suction device to confirm placement in a large gas containing space. Note that it is possible to get a CO₂ waveform with esophageal intubation, but this waveform will rapidly dissipate (decrease in size over 2-3 breaths). Esophageal intubation should be detected by auscultation over the stomach and chest.

Figure 17.

Confirmation of endotracheal tube placement by auscultation: Auscultate both lungs and stomach - sounds may be referred from stomach; bilaterally equal breath sounds -rule out endobronchial intubation; CO₂ detector; pulse oximetry is a late indicator of incorrect placement of the tube.

If correct placement of the endotracheal tube is confirmed by auscultation and CO₂ measurement, secure the endotracheal tube to the patient with tape or an endotracheal tube securing device. After the tube is secured, auscultation should be performed again to ensure the tube was not moved during taping.

Further steps after intubation

If you do not hear breath sounds over the chest, or if the patient is difficult to ventilate, or if you hear bubbling over the stomach with each delivered breath, then the endotracheal tube is in the esophagus and must be removed immediately.

Replace the mask and ventilate the patient by mask for 3 to 4 breaths before maneuvers such as changing to a more optimal blade or repositioning the patient are accomplished and a second attempt at endotracheal intubation is performed.

If the second attempt fails, try to have a more experienced laryngoscopist attempt the intubation. This should be done because even though you may be able to ventilate the patient by mask, continued intubation attempts may cause you to lose the ability to mask ventilate due to airway trauma (i.e. edema and/or bleeding). If unable to intubate the patient, you may be able to manage the airway with an LMA or combitube. This concept will be reviewed in detail under our advanced airway management section which will be created in this series.

COMPLICATIONS FROM AIRWAY MANAGEMENT

During anesthesia, difficulty in managing the airway is the most important cause of major anesthesia related morbidity and mortality.²⁰ Difficulties in managing the airway can occur during masking or intubation. When a patient is being mask ventilated, excessive positive airway pressures can insufflate the stomach with air and increase the chance of aspiration. If an inexperienced airway manager places an oral airway improperly, it may force the tongue into the oropharynx and increase airway obstruction. Improper placement of a supraglottic airway may also obstruct the airway and worsen ventilation. When a patient is being adequately ventilated by mask or other supraglottic means (such as an LMA), it may be preferable for providers who are not expert in intubation to continue ventilation by mask until an experienced intubator arrives to assist. Attempts to intubate, if the procedure is not successfully performed, may cause swelling of the airway or bleeding, which may result in loss of the airway (inability to mask ventilate or intubate the patient).

Complications of Intubation

When an intubation is performed, the most common complication of intubation is damage to the teeth. This is not life threatening unless the tooth is dislodged into the oral cavity and is aspirated into the trachea or bronchi. Other common complications of endotracheal intubation include laceration of the lips, tongue or pharynx. These are generally not serious unless the trauma to the tongue or pharynx causes excessive swelling and bleeding which makes visualization of the glottic opening so difficult that the intubation cannot be performed, creates an aspiration problem from bloody secretions or results in the inability to mask or ventilate the patient (loss of the airway). Hemodynamic changes may occur during laryngoscopy which can cause a significant sympathetic stimulation if the patient is not adequately anesthetized. These changes may result in cardiac ischemia or vascular accident. Laryngospasm may also occur in the inadequately anesthetized patient. This usually resolves with holding positive pressure under mask but may require administration of a muscle relaxant (succinylcholine). Bronchospasm may occur from tracheal irritation. This may require treatment with inhalation of epinephrine or isoproterenol or a beta-agonist (such as albuterol, metaproterenol, or terbutaline) or by deepening the level of a volatile anesthetic.²⁰ Other less common complications of intubation include perforation of the trachea or esophagus, retropharyngeal dissection, fracture of the cervical spine, or increased intracranial or intraocular pressure. In the case of the difficult-to-intubate patient who is also difficult to mask ventilate, hypercarbia, hypertension, and cardiac arrhythmias may be seen. To mitigate the complications of intubation, it is important to optimize intubating conditions during the “first look” (i.e. first attempt at intubation). This can be done with placing the patient in the most optimal intubating position, having an experienced laryngoscopist perform the intubation and anticipating difficult intubations which would allow the intubator to consider alternate methods of securing the airway such as a fiberoptic or awake intubation. Attempts at intubation must be carefully performed to prevent converting an airway which may be mask ventilated into a more swollen airway in which mask ventilation may not be possible.²⁰

SUMMARY

Anesthesia providers maintain patent airways, provide mask ventilation or intubate patients as a part of their normal practice. But for most medical providers, intubation is a procedure that is rarely performed. This lack of practice makes it very challenging for a non anesthesia provider to accomplish successful intubations during emergency situations. A basic training module is provided to assist. Further training modules, intubation practice performed in a simulation laboratory and practice in the operating room mentored by anesthesia staff may increase the success and safety of out of operating room intubations.

Figure 5.

An example of Mallampati Class II: Tonsillar pillars and tip of uvula are hidden by base of tongue

Figure 6.

An example of Mallampati Class III: Only the soft palate is visible; a difficult intubation is predicted; consider awake intubation.