ANATOMY The cricothyroid membrane is located between the thyroid and cricoid cartilages ( Fig 1..6.-.2.A). Both of these structures are easily palpated. The cricothyroid membrane can be found approximately one-third the distance from the manubrium to the chin in the midline in patients with normal habitus ( Fig 16-.2.B).
In a patient with a short, obese neck, the membrane may be hidden at the level of the manubrium, while in a patient with a thin, long neck, it may be midway between the chin and the manubrium. The thyroid gland overlies the trachea; both of these structures are difficult to palpate.
FIG. 16-2. A. Anatomy of the neck. B. Location of the cricothyroid membrane.
The only vascular structure that may be injured during the course of a properly performed cricothyroidotomy is the thyroid ima artery, a branch of the aorta that runs up to the thyroid gland in the midline and infrequently reaches the level of the cricothyroid membrane. When injured, it needs to be surgically ligated to control the hemorrhage.
INDICATIONS AND CONTRAINDICATIONS Inability to orotracheally intubate an emergency patient is the prime indication for surgical or needle cricothyroidotomy. Orotracheal (or nasotracheal) intubation should be attempted first. In-line cervical stabilization must be maintained in trauma patients. If orotracheal intubation is unsuccessful, then cricothyroidotomy should be performed.
As mentioned earlier, surgical cricothyroidotomy is reserved for patients over the age of 12 years and is contraindicated in patients under the age of 12. Needle cricothyroidotomy is the procedure of choice in this age group.
COMPLICATIONS Acute complications following emergency cricothyroidotomy occur in up to approximately 10 percent of cases.5 Such complications include
1. Bleeding from the insertion site. Venous bleeding is almost always from small veins and usually stops (using a vertical neck incision decreases the chance of bleeding). Arterial bleeding can be from the thyroid ima artery or from a small artery at the base of the cricothyroid membrane. Apply gentle pressure to stop the bleeding. If bleeding persists, surgical control may be necessary in the operating room.
2. Misplacement of the tube. In an obese neck, it is possible to place the tube anterior to the larynx and trachea into the mediastinum. Ventilation is not possible. Manifestations of an incorrectly positioned tube are high airway pressures, absent breath sounds, and massive subcutaneous emphysema. The tube should be removed and a second attempt should be made.
3. Laceration of the structures of the neck. Laceration of the trachea, esophagus, or recurrent laryngeal nerves is extremely rare and is due to inadequate knowledge of the anatomy of the neck.
4. Pneumothorax. This complication is probably secondary to barotrauma caused by ventilation initiated immediately after tube placement.
Late airway complications may occur in up to 52 percent of cases. These complications include voice changes and laryngeal and/or tracheal stenosis. 67 and 8 EQUIPMENT NEEDED
1. Personal protective equipment
2. Scalpel with number-10 blade (preferable due to its greater width) or a number-11 blade
3. A 6-mm endotracheal tube or 6-mm tracheostomy tube (preferred) (Do not use a tube that is larger than 6 mm. A larger size is difficult to place through the cricothyroid membrane.)
4. Tape to secure the endotracheal tube in place; cloth ribbon and sutures to secure tracheostomy tube in place
PATIENT PREPARATION AND POSITIONING The patient should be placed supine with the neck positioned in the midline. Povidone iodine solution should be quickly applied to the skin if time permits. If the patient still has a patent airway (albeit minimal), oxygen should be administered by mask.
1. Stand to one side of the patient at the level of the neck. A right-handed practitioner should stand on the right side, and a left-handed practitioner on the left side.
2. Locate the cricoid ring. Place the index finger at the sternal notch and palpate cephalad until the first rigid structure is felt (cricoid ring). Roll the index finger one finger breadth above to locate the "hollow" between the cricoid and thyroid cartilages. This is the cricothyroid membrane ( Fig, 1.6-3).
3. Using the thumb and middle finger of the nondominant hand, stabilize the two cartilages.
4. Use the scalpel to make a vertical incision in the midline between the two cartilages. The incision should go through the skin and subcutaneous tissues. The structures are superficial, and care should be taken not to incise deeper, since this may result in damage to the cricoid or thyroid cartilage or vascular structures.
5. With the scalpel blade positioned horizontally, perforate the cricothyroid membrane so that the blade goes in approximately half its length ( Fig 16:4).
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FIG. 16-4. Surgical cricothyroidotomy: puncturing the cricothyroid membrane with a scalpel blade.
6. Place the back end of the scalpel handle into the incision in the cricothyroid membrane to widen the opening ( Fig 16-5).
FIG. 16-5. Surgical cricothyroidotomy: placing the scalpel handle to widen the hole in cricothyroid membrane.
7. Place the endotracheal tube (or tracheostomy tube) in the opening ( Fig, 1.6-6).
FIG. 16-6. Surgical cricothyroidotomy: endotracheal tube in place.
8. Secure the tube carefully with a ribbon and/or adhesive tape. If using an endotracheal tube, take special care that the tube is in no more than 2 to 3 cm; otherwise, the tube will slip down the right main-stem bronchus with even minimal movement.
9. Connect to a bag-valve-mask device for ventilation. Check for breath sounds for ventilation. If no ventilation is heard bilaterally, then pull the tube out and reinsert it. Constantly recheck for breath sounds to ensure that the endotracheal tube is correctly positioned. If breath sounds are absent only on the left side, then the tube has been inserted down the right main-stem bronchus and needs to be pulled back a few centimeters. This usually occurs with the use of an endotracheal tube.
DRESSING AND STABILIZATION If a tracheostomy tube has been used, a simple dressing may be fashioned by cutting a slit halfway down the middle of a 4-by-4 cm dressing and placing it under the tracheostomy tube. This tube may be secured with a ribbon placed through the phalanges of the tracheostomy tube. For added security, 2-0 nylon sutures may be used to fix the tube to the skin. Endotracheal tubes are extremely difficult to secure properly to the neck and should be changed to tracheostomy tubes whenever possible.
DEVICE REMOVAL The cricothyroidotomy tube may be removed once the patient has a patent airway, or has been changed to a tracheostomy tube, as mentioned above. Patency may be evaluated by deflating the cuff of the tube and assessing airflow by breathing or by speech.
Needle cricothyroidotomy entails insertion of a catheter (generally an intravenous catheter) through the cricothyroid membrane. Although this procedure is easier to perform than surgical cricothyroidotomy, it is greatly inferior in providing adequate ventilation. The diameter of the catheter used is the limiting factor for airflow.
ANATOMY See the discussion under "Surgical Cricothyroidotomy."
INDICATIONS AND CONTRAINDICATIONS The general indications are listed under "Surgical Clicothyroidotomy." However, needle cricothyroidotomy is usually deemed the only type of emergency surgical airway that is indicated in children under the age of 12 years. Although generally there are no contraindications to needle cricothyroidotomy, adult patients can be ventilated for only approximately 15 to 20 min and should have an alternative airway secured immediately (by surgical cricothyroidotomy, endotracheal intubation, or tracheostomy).
COMPLICATIONS Complications after needle cricothyroidotomy are less frequent than after surgical cricothyroidotomy. Bleeding at the puncture site and infection may occur. Inadvertent perforation of the esophagus or back wall of the trachea or larynx is infrequent. Massive subcutaneous emphysema will develop during ventilation. The catheter may also be misplaced in the soft tissues of the neck.
1. Personal protective equipment
2. A 14- or 12-gauge sheathed needle catheter
3. A 3-mL syringe
5. Wall oxygen source at 15 L/min (40 to 50 lb/in2) connected by tubing with a Y connector or fashioned with a side hole (a bag-valve-mask device can be substituted but is not optimal)
PATIENT PREPARATION AND POSITIONING See the discussion under "Surgica]C£icoihyro.!dotomy.!
STEPS OF PROCEDURE
1. The operator should be positioned above the head of the patient.
2. Locate the cricoid ring. Place the index finger at the sternal notch and palpate cephalad until the first rigid structure is felt (cricoid ring). Roll the finger one finger breadth above to locate the "hollow" between the cricoid and thyroid cartilages. This is the cricothyroid membrane ( Fig 1.6-7).
3. Attach a 3-mL syringe to the catheter (12- or 14-gauge).
4. Introduce the catheter into the subcutaneous tissue at a 90° angle to the skin. Aspirate gently while advancing the catheter over the needle. When air suddenly returns (indicating entry into the airway), change the angle to 45°, and advance the catheter over the needle into the larynx. Withdraw the needle and syringe
FIG. 16-8. Needle cricothyroidotomy: puncturing the skin with the needle and catheter.
5. Disconnect the 3-mL syringe from the bare needle.
6. Withdraw the plunger from the syringe and attach the plungerless 3-mL syringe barrel to the catheter in the neck.
7. Attach the adapter (from the end of a 7-mm endotracheal tube) to the end of the inserted catheter or the open end of the 3-mL syringe ( Fig, 16..-.9 and Fig.
16.-10.), or place a 7-mm endotracheal tube into the empty syringe barrel and inflate the balloon ( Fig 16z11).
FIG. 16-11. Needle cricothyroidotomy: endotracheal tube-syringe-catheter setup.
8. Attach the oxygen source to the adapter and start ventilation using 100% oxygen. Intermittent jet insuflation (50 lb/in 2) can be achieved by occluding the Y connector or side hole in the connecting tubing. Insuflate 1 s; then release the occlusion for 4 s. To achieve the required high pressures, it is best to use a jet injector regulated by a flowmeter attached to a wall unit on a tank. An unregulated wall unit or tank is a less optimal choice.
9. The operator must hold the catheter in place at all times until a definitive airway is obtained. The catheter is easily displaced with minimal movement. (The inspiration-to-expiration ratio may be as high as 1:10 or 1:15 due to the high resistance to flow. Ventilation will be inadequate, and a definitive airway must be obtained. This is only a temporary airway.)
DRESSING AND STABILIZATION Stabilization is achieved by the operator until another choice of airway is established, either tracheostomy or oro- or nasotracheal intubation (if possible). Dressings are not necessary.
DEVICE REMOVAL A needle cricothyroidotomy catheter should be removed as expediently as possible. The catheter almost always becomes inadvertently dislodged from the airway, and the ability to ventilate is poor.
1. Erlandson MJ, Clinton JE, Ruiz E, Cohen J: Cricothyroidotomy in the emergency department revisited. J Emerg Med 7:115, 1989.
2. Sise MJ, Shackford SR, Cruickshank JC, et al: Cricothyroidotomy for long-term tracheal access: A prospective analysis of morbidity and mortality in 76 patients. Am Surg 200:13, 1984.
3. Grewal H, Rao PM, Mukerji S, Ivantury RR: Management of penetrating laryngotracheal injuries. Head Neck 17(6):494, 1995.
4. Esses BA, Jafek BW: Cricothyroidotomy: A decade of experience in Denver. Ann Otol Rhino Laryngol 96:519, 1987.
5. Isaacs JH Jr, Pedersen AD: Emergency cricothyroidotomy. Am Surg 63:346, 1997.
6. Gleeson MJ, Pearson RC, Armistead S, Yates AK: Voice changes following cricothyroidotomy. J Laryngol Otol 98:1015, 1984.
7. Kuriloff DB, Setzen M, Portnoy W, Gadaleta D: Laryngotracheal injury following cricothyroidotomy. Laryngoscope 99:125, 1989.
8. Holst M, Hertegard S, Persson A: Vocal dysfunction following cricothyroidotomy: A prospective study. Laryngoscope 100:749, 1990.
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