Limited clinical evaluation of an intubated patient
Table 3.2.Indications for intubation
Indication
Rationale
Comments
Ventilation
The patient is not safely breathing on their own
Circumstances make it difficult to match the patient’s inherent drive (e.g., salicylate toxicity)
Oxygenation
Intubation allows high FiO2 and positive end-expiratory pressure
Noninvasive ventilation may suffice for many patients
Protection
Alterations in mental status may blunt protective airway reflexes, and conditions such as vomiting may result in aspiration
Obstructive processes (e.g., expanding hematoma) may threaten tracheal patency
Expected course
A presently stable patient may be expected to deteriorate
Early intubation is often safer prior to deterioration
Metabolic demand
Decrease work of breathing in critically ill patients (e.g., severe sepsis)
Oxygen consumption from respiration alone can rise from baseline of 5% to 50%
Noninvasive ventilation
In patients protecting their airway, noninvasive ventilation (NIV) may be appropriate.
Many patients will improve dramatically with NIV and avoid intubation.
NIV provides:
Up to 100% FiO2
Pressure-support, decreasing the work of breathing
PEEP, overcoming shunt physiology (e.g., severe pneumonia, acute pulmonary edema).
Although alteration in mental status is a traditional relative contraindication to NIV, critically ill emergency department (ED) patients can be closely monitored by experienced airway operators.
NIV can be used to achieve two simultaneous goals:
It can potentially improve the patient sufficiently to obviate the need for intubation.
Barring sufficient improvement, NIV will optimize preoxygenation if intubation is necessary.
Oxygenation
Oxygenation is the primary concern in airway management.
As hemoglobin and oxygen bind cooperatively, desaturation is slow above SpO2 90%.
Below 90%, hemoglobin molecules quickly lose bound oxygen, and critical hypoxia can occur in seconds.
Due to the technical aspects of pulse oximetry, there is a lag of up to 2 minutes in the measured SpO2. Therefore, a reading in the 80–90% range may indicate that the actual SpO2 is much lower.
Laryngoscopy should be abandoned when SpO2 reads 90% in order for the patient to be reoxygenated.
Laryngoscopy and intubation
The following steps are necessary to place an endotracheal tube (or an EGA):
Positioning
Oxygenation
Equipment and discussion of back-up plan
Medication administration
Laryngoscopy and intubation (or EGA placement)
Postintubation management.
Positioning
Proper positioning is essential for laryngoscopy.
The same positioning principles will aid in preoxygenation and mask ventilation.
Proper positioning lifts the anterior pharyngeal structures off the posterior pharynx and optimizes glottis view.
A combination of head, neck, and body positioning can be used to optimize both of these goals.
Jaw thrust: lifting the jaw anteriorly by the angles of the mandible to open the pharynx.
Ear-to-sternal-notch: the patient’s head should be elevated in order for the external auditory meatus to be at the same level as the manubrium, in a plane parallel to the ceiling (Figure 3.2a).
Some patients (including: obese, with pleural effusions, at risk for vomiting) may benefit from elevating the head of the bed to 30 degrees while maintaining the same positioning principles (Figure 3.2b).
Positioning for a video laryngoscope (VL):
VL with conventional blades: positioning is unchanged.
VL with an angulated blade: completely neutral head and neck position, with the head flat on the bed and the face plane parallel to the ceiling.
Figure 3.2. Patient positioning.
Preoxygenation
The goal of preoxygenation is not merely to achieve an SpO2 of 100%, but also to de-nitrogenate the lungs, completely filling the lungs with oxygen to act as an oxygen reservoir during laryngoscopy.
Preoxygenate with a non-rebreather mask (NRB) set to 15 liters per minute or higher, for at least 3 minutes.
If hypoxia persists despite high-flow oxygen, the patient is likely shunting and may require PEEP delivered via NIV.
Obtunded hypoxic patients, if still ventilating on their own, may be safer to ventilate with NIV under close supervision than with bag-mask ventilation.
In the apneic patient, bag-mask ventilation (BMV) should be performed.
Two-operator technique will provide a better mask seal as one operator can use both hands to secure the mask to the patient’s face.
Nasal trumpets and oral airways, if tolerated, can be invaluable in maintaining pharyngeal patency.
Use slow, smooth, controlled breaths of only half the volume of a standard bag.
Patients obtunded due to severe metabolic acidosis will require a much faster respiratory rate, and must be ventilated during the apneic period to avoid cardiac arrest.
Most bags accept a PEEP valve if necessary.
Ventilators can be attached to masks, allowing for control of tidal volumes, respiratory rate, and PEEP if needed.
Fully obtunded and apneic patients oxygenate better with the rapid placement of an EGA.
Apneic oxygenation and oxygenation during laryngoscopy
NRB should be left in place during the apneic period.
As the oxygen in the lungs is filtered into the body, an O2-gradient is established allowing passive flow of oxygen from the high-FiO2 of the NRB to the lungs.
A nasal cannula set to 15 lpm will similarly provide high-flow oxygen during laryngoscopy.
If there are insufficient oxygen wall adaptors to provide three sources of oxygen (bag-mask, NRB, and nasal cannula), place a portable oxygen tank under the bed to provide a third source.
Extraglottic airways
Numerous EGA options exist, primarily laryngeal tubes (mainly used in the pre-hospital setting) and laryngeal masks.
EGA are typically used as rescue devices when it is difficult to provide BMV.
Laryngeal masks do not fully “secure” the airway as vomit may dislodge them.
Many second-generation laryngeal masks permit intubation through the mask.
Laryngoscopy
Principles of laryngoscopy are identical for direct and video laryngoscopy, with the exception of different positioning.
Suction should be available under the patient’s right shoulder. Two or more Yankauer suction tips may be necessary if blood, vomit, or copious secretions are expected.
Various devices exist for video laryngoscopy.
Many devices use traditional curved blades and may be used either directly or with the video monitor.
Devices with angulated or indirect blades are operated similarly but do not allow for direct visualization.
Angulated blades will often insert too far; if the glottis cannot be seen, withdraw slowly.
Lifting the handle straight toward the ceiling may also improve the view.
Video devices improve views but may be defeated by blood, mucus, or vomit.
Tube delivery may be more difficult as the angle of attack to the trachea is steeper.
Stylets vastly improve tube control and delivery and should be shaped straight to the cuff, then angled to 35 degrees.
Deliver the tube from the side (3-o’clock): rotation about the long axis will give subtle control in the vertical axis, and the tube will not obscure the glottic view.
A partial glottic view is sufficient if the tube can be directed above the posterior cartilages (Figure 3.3).
Tube delivery with angulated VL is often facilitated with malleable stylets shaped similarly to the blade, or with proprietary stylets.
Figure 3.3. View of the vocal cords. Grade I: the entire glottis opening is visualized. Grade II: only the posterior aspect of the glottis opening is visualized. Grade III: only the tip of the epiglottis is visualized. Grade IV: only the soft palate is visualized.
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Figure 3.1. (© Reuben Strayer & emupdates.com, used with permission. Adapted from: Reuben Strayer. Emergency Department Intubation Checklist v13. 2012. http://emupdates.com/2012/07/08/emergency-department-intubation-checklist-v13/; accessed July 23, 2012). 
Figure 3.2. Patient positioning. 
Figure 3.3. View of the vocal cords. Grade I: the entire glottis opening is visualized. Grade II: only the posterior aspect of the glottis opening is visualized. Grade III: only the tip of the epiglottis is visualized. Grade IV: only the soft palate is visualized. 
