Endotracheal Intubation

Christopher J. Wolcott, MD
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Subject: Endotracheal Intubation

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Introduction

Endotracheal intubation is a critical, life-saving procedure. To perform the procedure, physicians must rapidly assess the adequacy of the patient’s airway and need for ventilatory support. Once the decision to intubate has been made, the procedure should be performed rapidly and skillfully to prevent further deterioration or injury. 
The decision to intubate is determined by the patient’s failure to (i) oxygenate, (ii) ventilate, or (iii) protect the airway. These problems can occur simultaneously. Failure to oxygenate refers to impairment of gas exchange at the level of the alveoli, resulting in hypoxia and/or hypercarbia. Examples of failure to oxygenate include the patient with pulmonary edema, pneumonia, or pulmonary embolus. Pulmonary fibrosis, asthma, and chronic obstructive pulmonary disease (COPD) are restrictive lung diseases that may lead to a failure to ventilate, or physically move air into and out of the lungs. Ventilatory failure is often the end result of respiratory conditions associated with an increased work of breathing, accessory muscle use, and fatigue. The young and the elderly are particularly susceptible to ventilatory failure from fatigue. 
The patient that cannot maintain airway patency or clear secretions requires intubation to protect the airway. Examples of patients who require intubation to prevent aspiration include those with altered mental status from intoxication, closed head injury, central nervous system insult, or severe systemic illness or injury. Patients who require intubation to prevent airway occlusion include those with trauma to neck, upper airway edema, and chemical or thermal burns. The decision to intubate for airway protection is not only based on the patient’s current airway status but also on the anticipated clinical course. Intervening early in a relatively stable patient prior to a predicted airway occlusion or compromise allows for a more controlled intubation with fewer complications or risks of failure. 
 
Table 17-1.
Premedication Drugs

Rapid Sequence Intubation (RSI) Procedure

A discussion of the technique of endotracheal intubation would not be complete without a discussion of rapid sequence intubation (RSI). RSI is systematic process in which deep sedation and muscle paralysis are used to expedite intubation. Assemble all equipment, check equipment status, select the tube, and confirm cuff integrity. Preoxygenate a spontaneously breathing patient with 100% oxygen. This will saturate the hemoglobin with oxygen and allow more time to place the endotracheal tube before the patient must be reoxygenated by bag-valve mask (BVM). Administer FiO2 of 100% for 3 minutes by a nonrebreather mask or have the patient take four vital capacity breaths of 100% FiO2. Note that using positive pressure ventilation with a BVM to preoxygenate or to reoxygenate after a failed intubation attempt can cause gastric distention and increase the risk of vomiting and subsequent aspiration of gastric contents. If the patient is apenic or requires ventilatory support between intubation attempts, the BVM can be used with cricoid pressure. Gentle downward pressure on the cricoid cartilage will compress the esophagus and reduce the chance of gastric insufflation. 
Premedication refers to drugs given 3 to 5 minutes prior to sedation and muscle paralysis to blunt the “pressor response” of intubation (Table 17-1). This is the physiologic response caused by manipulation of the larynx, causing an increase in heart rate, blood pressure, intracranial pressure (ICP), and intraocular pressure (IOP). 
The induction phase refers to administration of medications to produce deep sedation (Table 17-2). These drugs are given by rapid intravenous push. 
 
Table 17-2.
Induction Agents
 
Table 17-3.
Paralytics
Finally, give an intravenous paralytic after sedation occurs (Table 17-3). Avoid succinylcholine use in major crush or burn injuries or in any condition with a risk of hyperkalemia. Apply cricoid pressure to reduce the risk of gastric aspiration. Once a neuromuscular blockade is induced, the patient loses protective airway reflexes. Place the endotracheal tube as described in Step 10, confirm its position, and secure it. 

Equipment

All necessary equipment should be kept in an accessible, consistent location. In an emergency department, it is recommended to check the equipment each morning to ensure it is complete and in good working condition. 
  • Laryngoscope handle (adult and pediatric) with charged batteries

  • Laryngoscope blades of various size (shown in Step 1):

    • Miller nos. 3 and 4 for most adults

    • Macintosh nos. 3 and 4 for most adults

    • Miller no. 0 for premature infants and neonates

    • Miller no. 1 for term infants

    • Miller no. 2 for small children

  • Endotracheal tubes of various sizes (shown in Step 2):

    • 7.0 to 7.5 mm for most adult females

    • 7.5 to 8.0 mm for most adult males

Although these sizes are the most common, tubes from 2.5 mm to 9 mm should be available. 
  • BVM attached to high-flow oxygen source

  • Suction with tip

  • Nasopharyngeal and oropharyngeal airways (shown in Step 1)

  • Capnography device (shown in Step 11)

  • Stylet

  • Spare batteries and light bulbs

  • Tracheal tube securing device:

    • Tape and mastic

    • Tracheal cloth ties

    • Commercial devices

  • Magill forceps to remove foreign material in posterior oropharynx

Indications

  • Respiratory or cardiopulmonary arrest

  • Severe exacerbation of a chronic medical condition, resulting in an unstable patient who cannot oxygenate and/or ventilate, which leads to

    • Hypoxia despite appropriate therapy

    • Hypercarbia, especially with altered mental status

    • Failure to ventilate because of

      • Fatigue

      • Airway obstruction

      • Neuromuscular disease

  • Trauma:

    • Central nervous system trauma associated with Glasgow coma scale (CS) ≤8

    • Injury to neck with airway compromise—Listen for stridor or voice changes:

      • Penetrating trauma associated with expanding hematoma

      • Blunt trauma associated with hematoma

    • Severe flail chest

    • Pulmonary injury resulting in poor oxygenation or ventilation

    • Multisystem trauma resulting in an unstable patient

  • Loss of airway protection because of altered mental status:

    • GCS ≤8

    • Advanced disease process

    • Intoxication

    • Sepsis

  • Anticipated clinical course:

    • Predicted decompensation of medical condition leading to respiratory failure

    • Severely injured patient requiring emergent surgery

    • Inhalation thermal injuries

    • Chemical injuries to the airway

    • Patient with increased work of breathing and fatigue despite therapy

    • Transfer of a patient to another facility with any of the previously mentioned conditions

Contraindications (Relative)

  • Unstable cervical spine fracture is a relative contraindication but should not prevent intubation when it is required to sustain life. If time permits, a clinician skilled in fiber optic laryngoscopy can intubate with minimal manipulation of the cervical spine.

  • Severe facial trauma is a relative contraindication but should not prevent intubation when it is required to sustain life. Debris and blood may prevent visualization of the vocal cords. Cricothyrotomy should be considered in this situation.

The Procedure

Step 1

Prepare the equipment. Confirm the bulb on the laryngoscope is working and properly fits the handle. Inflate the cuff on the endotracheal tube to ensure integrity, and insert the stylet. The equipment should also contain oropharyngeal and nasopharyngeal airways to enable more efficient bag valve mask ventilation should it be needed. 

Step 2

Evaluate for a difficult airway. This allows the physician to choose the equipment and method of intubation that will be most successful. If the clinician feels there may be a difficult airway, then another method of intubation should be considered (Table 17-4). 
 
Table 17-4.
Alternatives to Orotracheal Intubation
  • PITFALL: Factors contributing to difficult intubation include these:

    • An obese patient with a short “bull” neck: This patient will be harder to position and will deoxygenate more quickly. The larynx in a patient with a short neck is often more anterior and higher than normal, leading to difficulty aligning the axes.

    • Large teeth and tongue or the inability to open the mouth more than 3 cm: This leads to less room to place and maneuver equipment in the mouth.

    • Trauma, blood, debris, or vomitus obscure landmarks.

    • Severe ankylosing arthritis or a cervical collar limits movement of cervical spine.

Step 3

Position the patient. Place the patient in the “sniffing” position by extending the head on the neck and flexing the neck in relation to the torso. This position better aligns the oral axis with the laryngeal and pharyngeal axes. In the figures, the oral axis is represented by the red line, the laryngeal axis by the blue line, and the pharyngeal axis by the green line. In the neutral position (A), the axes do not line up, making it very difficult to see along the laryngeal axis. Note how the axes are in better alignment when the patient is placed in the sniff position (B). 
  • PITFALL: A patient with a cervical spine injury should not have any movement of the neck and will be more difficult to position.

Step 4

After adequate sedation and paralysis (see the section on rapid sequence intubation), the physician opens the patient’s mouth by placing the right thumb on the lower incisors and right index finger on the upper incisors. Using a scissor-like motion to push the jaw inferiorly with the thumb, the mouth is opened. 

Step 5

The operator holds the laryngoscope in the left hand and inserts the tip of the laryngoscope blade between the tongue and the lingual surface of the right mandibular teeth. As the blade is advanced along the lingual surface of the teeth, the tongue is displaced to the left. 
  • PITFALL: If the blade is started in the center of the mouth, the tongue will not be adequately displaced to the left and will obscure the view.

Step 6

Advance the blade over the base of the tongue while keeping a gentle “up and out” force on the handle. This force should be directed along the long axis of the handle of the laryngoscope represented by the black arrow. Remember to keep the tongue displaced to the left. 
  • PITFALL: Rotation of the handle represented by the red arrow in the figure instead of lifting up and out along its axis will lead to the handle or blade pressing against the lips and teeth, causing lacerations or avulsions.

Step 7

If using a Macintosh blade, advance the tip of the blade into the vallecula while maintaining the up and out force. 
  • PITFALL: Pushing the Macintosh blade too deeply into the vallecula will displace the epiglottis inferiorly, thus obscuring the view of the vocal cords.

Step 8

If using a Miller blade, place the tip just inferior to the epiglottis and lift up and out. 
  • PITFALL: If the Miller blade is passed beyond the epiglottis, the up and out force can lift the larynx and vocal cords out of view.

  • Pearl: If unable to visualize the vocal cords, the “B.U.R.P.” technique may be used. The clinician may apply backward, upward, and rightward pressure to the cricoid cartilage. This will maneuver the larynx into a more favorable position.

Step 9

When the vocal cords are visualized, an assistant should place the endotracheal tube with stylet in the operator’s right hand. The operator should never take their eyes off the vocal cords. 

Step 10

The endotracheal tube is inserted into the corner of the mouth to the right and parallel to the laryngoscope blade. This placement will prevent obscuring the view of the vocal cords. The tip of the tube and cuff should be advanced to the posterior oropharynx while continuing to visualize the vocal cords. Once the cuff is visualized passing the cords, it should be advanced 3 to 4 cm more and inflated. Topical paralysis of the cords can facilitate passage, either by placing 2 cc of 4% lidocaine down an endotracheal tube that is directly positioned above the vocal cords or by injecting lidocaine through the cricothyroid membrane to reach the cords. The membrane is identified by palpating the space inferior to the thyroid cartilage and superior to cricoid cartilage. A 31-gauge, 1-inch needle is passed at a 45-degree angle superiorly though the cricothyroid membrane toward the position of the vocal cords. Aspiration of air is essential to confirm placement in the airway. Lidocaine is injected into the cords to cause paralysis. 
  • PITFALL: Failure to observe the tube and cuff pass the vocal cords will increase risk of placing the tube into the esophagus.

  • PITFALL: Forcing the tube between the vocal cords can lead to vocal cord damage. See the section on complications.

Step 10
Step 10

Step 11

Confirm placement of endotracheal tube by first auscultating in the bilateral axillae and then epigastrum, followed by observing the chest rise and fall, end tidal CO2 detection, oxygen saturation, and chest x-ray. An Easy-Cap CO2 detector will change from purple to yellow when exposed to carbon dioxide. 
  • PITFALL: Failure to auscultate for breath sounds in the axillae may lead to a failure to identify a right mainstem bronchus intubation or esophageal intubation. In a right mainstem bronchus intubation, the clinician may hear breath sounds that have been transmitted from the right lung to the left when listening to the left parasternal area.

  • Pearl: The desired depth of the tube is 3 to 7 cm above the tracheal carina. This position will prevent damage to the carina by the tube if the patient’s head is flexed because flexion of the head can advance the endotracheal tube as much as 2 cm deeper into the trachea.

Step 11
Step 11

Step 12

Secure the endotracheal (ET) tube using tape with mastic, tracheal cloth ties, or a commercial device. The process of using tape to secure ET tube is shown in the figure. Split tape longitudinally as shown. Apply upper segment of tape to face and philtrum and lower segment wraps around tube. Applying mastic to skin will help secure the tape to face. 
Step 12
Step 12

Step 13

Use of umbilical cloth tape as a trach tie is a well-tested method. Loop the tie and pass ends through the loop around the ET tube. Tie a knot around the tube and loop to secure it in place. Loop ends around patient’s head above one ear and below the other and tie ends together. 
Step 13
Step 13

Step 14

There are several types of commercial securing devices that come with their own specific instructions. In general, the clinician will apply an adhesive strip with loop-and-hook surface to the philtrum. Apply a head strap around the head and secure to the hook and loop surface across the philtrum. Secure the tube in a plastic holder. Wrap the tape around the tube and tube holder to secure in place. 
Step 14
Step 14

Complications

  • Right mainstem bronchus intubation:

    • ET tube is advanced too deeply, and the tip enters the right main stem bronchus.

    • This can cause atelectasis of left lung because of lack of air entering the left lung.

    • Operator should confirm position of the tube through auscultation of equal breath sounds in the axillae and on the chest radiograph.

    • If more intense breath sounds are heard over right side of chest, the tube should be withdrawn while auscultating until equal breath sounds are heard.

  • Esophageal intubation:

    • Endotracheal tube is inadvertently placed into the esophagus.

    • Intense air movement is heard over the epigastric area while no breath sounds are heard in lung fields.

    • The patient’s vital signs will deteriorate.

    • Some physicians remove the misplaced tube and perform another attempt. Other physicians leave the misplaced tube in place and attempt endotracheal intubation using the misplaced tube to mark the esophagus.

  • Vocal cord trauma:

    • Attempting to force an oversized ET tube through narrow vocal cords may cause damage to the cords.

    • Selecting a smaller ET tube will allow easier passage of the tube.

  • Oral trauma:

    • Damage to the teeth and lips is common. This usually occurs when the operator attempts to improve visualization by pivoting the laryngoscope in the mouth (shown in Step 6). This will cause the handle to push against the teeth and lips. If all broken teeth and fragments cannot be accounted for, a chest radiograph must be obtained to determine their location.

    • To avoid oral trauma, the laryngoscope handle should be lifted in the “up and out” manner.

  • Tracheal perforation by the stylet: The stylet should not extend beyond the tip of the ET tube.

  • Aspiration: Positive pressure with the BVM may lead to gastric distention. Cricoid pressure and minimizing BVM use will decrease the amount of gas in the stomach.

  • Pneumothorax can occur with positive pressure ventilation especially if the patient has poor lung compliance or if the ET tube was placed in the right mainstem bronchus.

  • Arrhythmias may be caused by manipulation of the oropharynx by the laryngoscope. Also, prolonged attempts to place the ET tube may lead to hypoxia, bradycardia, or asystole. Premedication with atropine can blunt the bradycardic response to intubation.

Pediatric Considerations

A child’s physiologic response to medical conditions differs from that of an adult. For example, an adult’s vital signs may gradually deteriorate with disease progression, allowing the clinician time to respond to an impending cardiovascular or respiratory collapse. In contrast, vital signs in children may remain virtually normal despite progressive deterioration, providing little warning of the need for intervention. Grunting, retractions, nasal flaring, and lethargy are all indicators of poor respiratory status in a pediatric patient. 
If the child requires intubation, preoxygenation is critically important. Children cannot tolerate apnea as long as an adult, and shorter attempts to place the tube are warranted. During apnea, a preoxygenated 10-kg child will maintain nearly 100% SaO2 for approximately 2 to 3 minutes and drop to <90% SaO2 at approximately 4 minutes. The child will then drop from 90% to 0% in <45 seconds. A preoxygenated 70-kg adult will maintain oxygen saturation >90% for 8 minutes and then drop from 90% to 0% in 120 seconds. 
A child’s anatomy is also different from the adult’s. The child’s head and occiput are proportionally larger and may keep the head in a flexed position. Placing a towel or roll under the shoulders will help extend the neck. Further, the child’s tongue is proportionally larger and takes up more of the mouth than in an adult. The tongue must be controlled with the laryngoscope blade to obtain adequate visualization. Finally, the larynx in a child is more proximal than in an adult. This may lead to the placement of the laryngoscope blade too deeply and into the esophagus. Visualization of the entrance of the blade into the posterior oropharynx and advancement into larynx will help identify anatomical structures. A Miller blade is often preferred for infants and children. 

Postprocedure Instructions

After the ET tube is placed and confirmed to be in the correct position, the physician must secure the device using tape and mastic, 0.5-inch cloth umbilical tape, or a commercial device. Ventilator settings must be made. The settings will be based on the patient’s weight, medical problem, condition, and desired effect. Settings include but are not limited to ventilator mode, tidal volume, rate, pressure, and oxygen concentration. 
  • Ventilator modes:

    • Continuous mechanical ventilation (CMV) or assist/control. The ventilator delivers a minimum number of breaths per minute at a set tidal volume (control breath). If the patient takes a breath independently, the ventilator will deliver the preset tidal volume (assist breath). This mode is generally used for patients who are not breathing spontaneously.

    • Synchronized intermittent mandatory ventilation (SIMV). The ventilator delivers a minimum number of ventilations per minute with a set tidal volume as in CMV. However, the patient may breathe spontaneously at rate greater than the ventilator setting and at their own tidal volume. This mode is used when patients are being weaned from the ventilator to allow them to breathe some on their own without risk of respiratory failure due to fatigue.

    • Continuous positive airway pressure (CPAP). The ventilator assists with inhalation by delivering a predetermined pressure in the circuit. This pressure decreases the work of breathing by allowing the patient to overcome airway resistance with less effort. The tidal volume and respiratory rate are determined by the patient’s effort. This mode may be used when determining if the patient can be extubated or in various restrictive and obstructive lung diseases.

    • Pressure regulated volume control (PRVC). A form of CMV in which a target volume is set on the ventilator and the ventilator will vary the inspiratory flow of each breath to achieve the set volume at the lowest possible peak pressure. The ventilator adjusts pressure from breath to breath, as the patient’s airway resistance and compliance change, in order to deliver a set tidal volume. It also measures the tidal volume of each breath and compares it to the set tidal volume. If the measured volume is less than the set volume, the ventilator will increase the inspiratory pressure to deliver the set tidal volume. If the measured tidal volume is more than the set volume, the ventilator will decrease the pressure. This setting may increase inspiratory time to deliver the set volume without raising pressure above its set upper limit. The PRVC setting is not recommended in asthma or COPD because a longer inspiratory time may cause air trapping and auto-PEEP (positive end-expiratory pressure).

  • Tidal volume (VT):

    • VT is the volume of air inspired and expired during each breath.

    • In the past, many experts recommended 10 mL/kg as a good starting point. However, more recent data suggest a lower tidal volume of 6 to 8 mL/kg reduces the risk of barotrauma and ventilator-induced lung injury.

  • Respiratory rate:

    • The rate should be adjusted to approach a minute ventilation of 100 mL/kg. This minute ventilation is required to remove carbon dioxide produced by metabolism.

    • The rate should be adjusted with the following considerations:

      • The febrile patient produces 25% more carbon dioxide and requires 25% more breaths.

      • A hypercapneic patient may transiently require an increased respiratory rate to remove excess CO2. However, providing adequate ventilations through intubation and mechanical ventilation to a previously hypoventilating patient may be sufficient enough to correct hypercapnea without the need for hyperventilation.

  • The rate should be adjusted based on blood gas analysis or end tidal CO2 monitoring.

  • Pressure (PEEP):

    • Pressure is applied to the airway to increase alveolar pressure and keep the small airways open.

    • It may be increased and can improve oxygenation by preventing alveolar collapse.

    • Excess pressure may elicit barotraumas.

    • Most start at 5 to 10 cm H2O.

  • Fraction of inspired oxygen (FiO2):

    • Concentration of oxygen delivered to the lungs

    • Usually begins with 100% and is titrated down based on arterial blood concentration of oxygen or pulse oximetry

Coding Information and Supply Sources

The ICD-9 code is used for this procedure is the indication for intubation (symptom/diagnosis). 
Supplies for this procedure can be purchased from almost any medical supply house. 

Bibliography

Bailey H, Kaplan LJ. Mechanical ventilation. In: Roberts JR, Hedges JR, eds. Clinical Procedures in Emergency Medicine . Philadelphia: Saunders;  2004:146–170.
Clinton JE, McGill JW. Basic airway management and decision-making. In: Roberts JR, Hedges JR, eds. Clinical Procedures in Emergency Medicine . Philadelphia: Saunders;  2004:53–68.
Clinton JE, McGill JW. Tracheal intubation. In: Roberts JR, Hedges JR, eds. Clinical Procedures in Emergency Medicine . Philadelphia: Saunders;  2004:69–99.
Danzl DF, Vissers RJ. Tracheal intubation and mechanical ventilation. In: Tintinalli JE, Kelen GD, Stapczynski JS, eds. Emergency Medicine: A Comprehensive Study Guide . New York: McGraw-Hill;  2004:108–119.
Dronen SC, Hopson LR. Pharmacological adjuncts to intubation. In: Roberts JR, Hedges JR, eds. Clinical Procedures in Emergency Medicine . Philadelphia: Saunders;  2004:100–114.
Murphy MF, Murphy GW. Mechanical ventilation. In: Walls RM, Murphy MF, eds. Manual of Emergency Airway Management . Philadelphia: Lippincott Williams & Wilkins;  2004:320–326.
Schneider RE, Caro DA. Neuromuscular blocking agents. In: Walls RM, Murphy MF, eds. Manual of Emergency Airway Management . Philadelphia: Lippincott Williams & Wilkins;  2004:200–211.
Schneider RE, Caro DA. Pretreatment agents. In: Walls RM, Murphy MF, eds. Manual of Emergency Airway Management . Philadelphia: Lippincott Williams & Wilkins;  2004:183–188.
Schneider RE, Caro DA. Sedative and induction agents. In: Walls RM, Murphy MF, eds. Manual of Emergency Airway Management . Philadelphia: Lippincott Williams & Wilkins;  2004:189–199.
Schneider RE, Murphy MF. Bag/mask ventilation and endotracheal intubation. In: Walls RM, Murphy MF, eds. Manual of Emergency Airway Management . Philadelphia: Lippincott Williams & Wilkins;  2004:43–69.
Walls RM. Rapid sequence intubation. In: Walls RM, Murphy MF, eds. Manual of Emergency Airway Management . Philadelphia: Lippincott Williams & Wilkins;  2004:22–32.
2008 MAG Mutual Healthcare Solutions, Inc.’s Physicians’ Fee and Coding Guide. Duluth, Georgia. MAG Mutual Healthcare Solutions, Inc. 2007.
 
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