I: Position the patient:
Ensure the bed is elevated to a level that is comfortable for the clinician. A rough guide is to position the patient’s head at the level of the clinician’s umbilicus. When preparing to intubate the patient’s trachea, the head and neck should be positioned using a combination of both cervical flexion and atlantooccipital (AO) extension. We describe this as the sniffing position. This enables the clinician to align the axes of the patient’s mouth, pharynx, and larynx during laryngoscopy (Fig. 6.6). In addition to the sniffing position, “ramping” up the upper thoracic spine using blankets or specially designed pillows (Troop Pillow) can be very useful to optimize the patient’s position prior to tracheal intubation.
Clinical Pearl:
Ideal positioning of the patient for direct laryngoscopy and tracheal intubation occurs when the external auditory meatus aligns in the same horizontal plane as the sternal notch when the patient is examined from the side (see Fig. 6.7, 6.8).
Atlantooccipital extension alone increases the angle between the axis of the pharynx and the larynx. By contrast, the combination of cervical flexion of the neck with AO extension results in the alignment of the axes of the pharynx and larynx.
Optimizing the position of the patient’s head, neck, and thoracic spine before attempting laryngoscopy is an important initial step to ensure a successful tracheal intubation. This is especially true in obese or pregnant patients (Fig. 6.8) or in cases of an anticipated difficult intubation. It is good practice to ensure that your first intubation attempt is your best attempt.
Clinical Pearl:
In addition to placing the patient in the sniffing position, ramping up the thoracic spine is an important maneuver to optimize the patient’s position prior to tracheal intubation.
Fig. 6.8 Ramping the thoracic spine to optimize the patients position for direct laryngoscopy and intubation. In addition to pillows under the shoulders and head, a special pillow (e.g., Troop pillow) can be used to ramp the thoracic spine (right image). The position is optimized when the tragus of the ear is in the same horizontal plane as the sternal notch.
Fig. 6.9 Direct laryngoscopy. A pillow is used to create cervical flexion. The operators right hand controls atlanto-occipital extension and facilitates the opening of the patient’s mouth. The curved laryngoscope blade has been inserted into the right side of the patient’s mouth, displacing the tongue to the left. The tip of the curved larygoscope blade is at the base of the tongue and epiglottis. An upward and forward (30 - 45 degree) lifting force is used to expose the glottis. Note the operator’s proper stance avoids a stooped posture.
II. Open the patient’s mouth:
The second step involves opening the patient’s mouth. First, the clinician stands directly behind the patient’s head and takes the laryngoscope in the left hand. The right hand is used to open the patient’s mouth and later to advance the ETT. Mouth opening can be accomplished by using the right hand to open the patient’s teeth (e.g., the scissors technique, as illustrated in Fig. 6.10) or by placing the right hand on the patient’s occiput and rotating the occiput backward to create AO extension (Fig. 6.9). Using the scissors maneuver, the clinician uses the index finger to pull up on the patient’s upper right incisors, which serves to open the patient’s mouth, extend the AO joint, and protect the teeth and lips. At the same time, the clinician uses the thumb to push down on the lower mandible and further open the patient’s mouth. This technique can be modified by opening the patient’s mouth using the right middle finger to depress the lower teeth (Fig. 6.10). If the clinician chooses the extra oral technique of mouth opening, the right hand is placed on the patient’s occiput and the patients’ head is rotated into the sniffing position. With this movement, the mandible drops and the patient’s mouth opens. This method of mouth opening is more suitable for the edentulous patient than the scissors technique.
Fig. 6.10 The scissors technique of opening the patient’s mouth for insertion of the laryngoscope. Left image: traditional scissors technique. The thumb pushes the mandible forward while the right index finger is used to pull back on the upper incisor. Right image: modified scissors technique.
Fig. 6.11 Common problems with direct laryngoscopy. I: Lifting the laryngoscope too early results in downfolding of the tongue, obscuring visualization of the glottis. II: Pushing the laryngoscope downward may cause the epiglottis to move posterior, obscuring the laryngeal view. III: Insertion of the laryngoscope blade too deeply (esophageal inlet) bypasses the glottic aperature.
III. Laryngoscopy:
The third step involves insertion of the laryngoscope into the patient’s mouth (Fig. 6.9, 6.10). The tip of the laryngoscope blade is advanced to the base of the patient’s tongue by rotating its tip around the tongue (Fig. 6.11). The laryngoscope blade should follow the natural curve of the oropharynx and tongue. The blade should then be inserted to the right of the tongue’s midline so that the tongue moves toward the left and out of the line of vision. The patient’s tongue should not be pushed into the back of the oropharynx, as visualization will be obscured. Once the tip of the blade lies at the base of the patient’s tongue (just above the epiglottis), firm, steady, upward and forward traction should be applied to the laryngoscope. The direction of force should be at 30° from the horizontal. Once the laryngoscope is properly positioned at the base of the tongue, avoid rotating it, as this action might exert pressure on the upper teeth and damage them. Damage is more common to the immobile upper maxillary teeth than to the lower mandibular teeth, which are free to move forward with the jaw during laryngoscopy. Fig. 6.12 shows how the larynx is more visible if the blade of the laryngoscope moves the patient’s tongue to the left of the mouth and out of the line of vision.
Students learning the technique of laryngoscopy universally adopt a stooped posture, placing their face within inches of the patient in an attempt to visualize the larynx. A stooped posture limits the power that can be exerted by their arm, making laryngoscopy technically more difficult to perform. In the stooped position, vision becomes monocular. The laryngoscope is typically rotated in an attempt to improve the view resulting in pressure being applied on the patient’s upper front teeth. With a stooped posture, it is difficult to visualize the upper teeth and larynx simultaneously while being aware of the pressure being placed on the upper teeth. By maintaining a more erect posture during laryngoscopy, an improved binocular view of both the teeth and larynx is possible. With a more erect posture the muscles of the arm and forearm can then be used to lift the soft tissues upward and forward with the left hand in the direction of the laryngoscope handle avoiding the need to rotate the laryngoscope with the wrist to improve the laryngeal view.
Laryngeal Anatomy:
In adults, the larynx is located at the level of the 4th to 6th cervical vertebrae. It consists of numerous muscles, cartilages, and ligaments. The large thyroid cartilage shields the larynx and articulates inferiorly with the cricoid cartilage. Two pyramidal-shaped arytenoid cartilages sit on the upper lateral borders of the cricoid cartilage. The aryepiglottic fold is a mucosal fold running from the epiglottis posteriorly to the arytenoid cartilages. The cuneiform cartilages appear as small flakes within the margin of the aryepiglottic folds.
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