Sunday, March 14, 2021

Emergency Tracheostomy Case File

Posted By: Medical Group - 3/14/2021 Post Author : Medical Group Post Date : Sunday, March 14, 2021 Post Time : 3/14/2021
Emergency Tracheostomy Case File
Eugene C. Toy, MD, Lawrence M. Ross, MD, PhD, Han Zhang, MD, Cristo Papasakelariou, MD, FACOG

CASE 50
A 47-year-old woman is undergoing surgical removal of her gallbladder (cholecystectomy). Her medical problems include insulin-dependent diabetes mellitus and sleep apnea. After the anesthesiologist has administered the paralyzing agent (succinylcholine), the patient experiences spasms of the airway and difficulty breathing with the bag and mask. The anesthesiologist attempts to place an endotracheal tube by direct visualization (direct laryngoscopy), without success due to swelling (laryngeal edema). Meanwhile, the oxygen saturation content of the blood has decreased to a very low range of 80 percent. The anesthesiologist remarks that an emergency airway needs to be surgically opened.

 What is your next step?
 What anatomical landmarks will be most helpful?


ANSWER TO CASE 50:

Emergency Tracheostomy
Summary: A 47-year-old woman with a history of diabetes and sleep apnea is undergoing elective cholecystectomy. After receiving the paralyzing agent, the patient develops laryngospasm and is difficult to ventilate. Direct laryngoscopy and intubation attempts are unsuccessful, and oxygen saturation is low.

• Next step: Emergency tracheostomy or cricothyroidotomy

• Helpful anatomical landmarks: Cricoid and thyroid laryngeal cartilages


CLINICAL CORRELATION
A leading cause of mortality at elective surgery is related to anesthesia, specifically an inability to ventilate the patient. This woman is probably obese and difficult to intubate because of her short neck, and her sleep apnea is a concern. When oxygen saturation decreases to dangerous levels (<90 percent), brain and/or heart ischemia may ensue. Immediate correction of oxygenation is critical, and, as in this case, emergency tracheostomy is indicated. One of the most expedient methods is to enter the cricothyroid membrane in the midline, between the cricoid and thyroid laryngeal cartilages. This interval is usually palpable and is approximately one-third the distance from the top of the manubrium to the tip of the chin (mentum). A vertical incision is made in the membrane, and a tracheal tube is inserted. Alternatively, a needle can be inserted into the same membrane, and oxygen can be administered through a jet ventilator. However, this procedure must be revised rapidly because there is insufficient flow to remove carbon dioxide from the lungs. Nonemergency tracheostomies are performed inferiorly to the cricoid cartilage and the isthmus of the thyroid gland.


APPROACH TO:
The Neck: Upper Airway

OBJECTIVES
1. Be able to list the landmarks of the anterior neck and identify the muscles of the infrahyoid region
2. Be able to describe the cartilaginous skeleton of the larynx and the positions of the vocal cords in relation to palpable landmarks
3. Be able to describe the thyroid gland’s relationship to the larynx and its blood supply

DEFINITIONS
ABCs: This mnemonic reminds us that the priorities of emergency management are airway, breathing, and circulation.

ENDOTRACHEAL INTUBATION: Placement of a tube through the mouth or nose and through the vocal cords to secure the airway and/or provide mechanical ventilation.

TRACHEOSTOMY: Surgical establishment of an airway by an opening from the skin to the trachea. These are emergent when endotracheal intubation is impossible, and they are elective when the patient has need of a long-term airway.

CRICOTHYROIDOTOMY: Temporary method of establishing an airway by penetrating through the cricothyroid membrane. The procedure is nearly always performed emergently.

CHOLECYSTECTOMY: Surgical procedure to remove the gallbladder.

SLEEP APNEA: Condition in which the patient in unable to breathe because of temporary obstruction of the airway, usually occurring during sleep. Loud snoring, choking, or periods of cessation of breathing are typical.


DISCUSSION
Deep to the thin skin of the anterior neck is the platysma muscle, which is within the superficial fascia. Deep to the platysma are the infrahyoid (“strap”) muscles of the neck. The paired sternohyoid muscles extend from the posterior surface of the manubrium to the hyoid bone, and their medial borders are just lateral and parallel to the midline. The superior bellies of the omohyoid muscles lie just lateral to the sternohyoid muscles. Deep to these muscles are found the sternothyroid muscles, and continuing superiorly are the thyrohyoid muscles.

The skeleton of the larynx consists of the U-shaped hyoid bone, which lies at the level of the C3 vertebra, and nine cartilages. The epiglottis, thyroid, and cricoid cartilages are unpaired, whereas the arytenoids, corniculate, and cuneiform are paired. The thyroid cartilage, which resembles an open book, lies opposite the C4 and C5 vertebrae. Its two laminae are united anteriorly, and the laryngeal prominence (Adam’s apple) is easily palpated and typically visible in men. The cricoid cartilage is shaped like a signet ring; its larger laminar portion is posterior. It lies opposite the C6 vertebra. The thyroid cartilage is joined to the hyoid bone above and the cricoid cartilage below by ligaments and membranes. The true vocal cords extend from the vocal processes of the arytenoid cartilages atop the lamina of the cricoid cartilage to the posterior surface of the thyroid cartilage superior to the lower border of the cartilage (Figure 50-1). The interval between the thyroid and cricoid cartilages is closed by the cricothyroid membrane and is inferior to the true vocal cords (Figure 49-1). The cricothyroid muscle is also found laterally in this interval.

The thyroid gland, like the larynx, is enclosed within the pretracheal fascia. The large laterally placed lobes of the gland are applied to the surface of the laminae of the thyroid cartilage and the upper trachea, with the parathyroid glands

Emergency Tracheostomy anatomy

Figure 50-1. The larynx in coronal section, including the vocal cords.

embedded in their posterior surfaces. The right and left lobes are joined across the midline by the isthmus, which typically is inferior to the cricoid cartilage at the level of the second and third tracheal cartilage rings. In approximately 50 percent of individuals, a pyramidal lobe may be present that extends superiorly and overlies the cricothyroid membrane, but usually to one side of the midline. This remnant of the thyroglossal duct may be glandular or fibrous tissue. The thyroid and parathyroid glands are supplied by the paired superior thyroid arteries (direct branches from the external carotid arteries) and the inferior thyroid arteries, which are branches from the thyrocervical trunk. In 12 percent of individuals, a small midline artery, the thyroid ima artery, arises directly from the aortic arch or brachiocephalic trunk. It ascends on the anterior surface of the trachea to reach the isthmus.


COMPREHENSION QUESTIONS

50.1 A 24-year-old man is being evaluated for airway abnormalities. Palpation of the cricoid cartilage is normally at which vertebral level?
    A. C2
    B. C4
    C. C6
    D. T1

50.2 A 45-year-old woman is undergoing thyroid surgery for suspected thyroid cancer. The surgeon has taken a midline approach and encounters significant bleeding below the isthmus of the thyroid gland. Which of the following is the likely cause of the bleeding?
    A. Penetration into the trachea
    B. Superior thyroid artery
    C. Inferior thyroid artery
    D. Thyroid ima artery
    E. Inferior laryngeal artery

50.3 A 54-year-old woman has undergone partial thyroid resection due to a nontender cold nodule that likely represents cancer. One week after surgery, she complains of twitching of the right arm and “spasms” of both hands. Which of the following is the most likely explanation?
    A. Anxiety after surgery
    B. Effects of anesthesia
    C. Parathyroid glands removed
    D. Vagal nerve injury

50.4 An emergency cricothyroidotomy is thought to be warranted because of airway collapse and severe laryngoedema. Which of the following is the most accurate description of the location of the cricothyroid membrane?
    A. Immediately superior to the thyroid cartilage
    B. Immediately inferior to the thyroid cartilage
    C. Immediately inferior to the cricoid cartilage
    D. Just deep to the isthmus of the thyroid gland
    E. Immediately inferior to the hyoid bone


ANSWERS
50.1 C. The cricoid cartilage is usually located at the C6 vertebral level.

50.2 D. In up to 12 percent of individuals, a small midline artery, called the thyroid ima artery, arises from the aortic arch or brachiocephalic trunk and reaches the thyroid isthmus inferiorly.

50.3 C. The parathyroid glands are variably inside the thyroid gland. With resections of the thyroid, the small parathyroid glands may be affected, leading to decreased levels of calcitonin and, hence, hypocalcemia. The low calcium levels may cause clinical symptoms of muscle spasms, tetany, or even convulsions.

50.4 B. The cricothyroid membrane is just inferior to the thyroid cartilage and
superior to the cricoid cartilage.

ANATOMY PEARLS
 The cricoid cartilage lies at the level of the C6 vertebra.
 The true vocal cords lie superior to the cricothyroid membrane.
 The cricothyroid membrane is located inferior to the thyroid cartilage and superior to the cricoid cartilage.
A pyramidal thyroid lobe may overlay the cricothyroid membrane, close to the midline.
 In a small percentage of patients, a small midline artery, the thyroid ima, may directly supply the isthmus.

References

Gilroy AM, MacPherson BR, Ross LM. Atlas of Anatomy, 2nd ed. New York, NY: Thieme Medical Publishers; 2012:598−599, 601, 603. 

Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy, 7th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014:1018−1029, 1030−1032, 1045. 

Netter FH. Atlas of Human Anatomy, 6th ed. Philadelphia, PA: Saunders; 2014: plates 70, 76, 79−80.

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