Chapter 28. Transtracheal Aspiration

Transtracheal aspiration is a technique for the collection of bronchial secretions for laboratory evaluation and culture. This technique is useful when standard sputum collection has not provided adequate material or determination of the infective agent(s). Specimens collected by this technique are free of contamination from nasal, oral, and pharyngeal secretions. This technique was first described in 1959.1 Several modifications to the original technique have been made.2–5 This technique may be more properly named transcricothyroid membrane aspiration.

The most superficial portion of the cervical airway begins at the inferior thyroid cartilage and extends inferiorly to the thyroid isthmus (Figure 28-1). The inferior border of the thyroid cartilage is attached to the cricoid cartilage by the cricothyroid ligament. This is formed by a thicker central conus elasticus and laterally by thinner ligaments that are covered by the cricothyroid muscles (Figure 28-1B). The internal surface is covered by the mucous membrane of the larynx. Collectively, this is often referred to as the cricothyroid membrane or cricovocal membrane. The paired cricothyroid arteries cross from lateral to medial to form an arch that anteriorly crosses the upper one-third of the cricothyroid membrane. The pyramidal lobe of the thyroid occasionally extends superiorly to this level.

Transtracheal aspiration is indicated for the collection of tracheobronchial secretions for laboratory evaluation. Often, previous attempts to collect standard coughed and expectorated sputum samples have failed to yield adequate samples or reveal the etiology of a pulmonary infection. Patients who do not appear to be responding to the appropriate antibiotic regimen that was indicated by evaluation and culture of sputum samples may benefit from this technique to better determine the pathogen(s). This is particularly true in cases of atypical or mixed flora, as in suspected aspiration pneumonias, where this technique may yield superior culture results when compared to sputum samples.6

Patients who are unable to cooperate with or tolerate the required positioning should not be selected for this technique.7 Agitated patients requiring sedation that may affect respiratory effort should be avoided. Traumatically injured patients should have the cervical spine cleared for possible injury prior to performing the procedure. Patients with known or suspected blood dyscrasias (e.g., abnormal platelet counts, elevated prothrombin, or partial thromboplastin times) should not be subjected to this technique due to the increased risk of tracheal hemorrhage. The physician must be able to easily identify the patient's anatomic landmarks, including the thyroid and cricoid cartilages and the intervening cricothyroid membrane. Patients with abnormal or distorted anatomy should be excluded. Patients who are endotracheally intubated or have a tracheostomy do not require this procedure.

• Sterile gown, gloves, and mask
• Pillow or padding for shoulders
• Povidone iodine solution or chlorhexidine solution
• Sterile gauze squares
• Normal saline solution, sterile and preservative-free
• Local anesthetic solution, 3 mL (1% lidocaine HCl)
• 3 mL syringes
• 30 mL syringe
• 25 to 27 gauge needles, ½ in
• 18 to 22 gauge catheter-through-the-needle
• 18 to 22 gauge catheter-over-the-needle, 3 in long
• 18 to 19 gauge needles, 1 ½ in
• Pulse oximeter
• Cardiac monitor
• Sterile specimen container
• Bandage, 1 in wide
• Sterile drapes or towels
• Resuscitation equipment including emergent airway management supplies

Explain the procedure, its risks, and its benefits to the patient and/or their representative. Obtain an informed consent. Place the patient on cardiac monitoring and continuous pulse oximetry. Administer supplemental oxygen and establish intravenous access.

Sedation is not generally required. A small dose of midazolam (1 to 5 mg IV) may be used, if appropriate, for light sedation. Deep sedation should be avoided, as it may compromise respiratory efforts and increase the risk of aspiration of gastric contents.

Place the patient supine in bed. Place a pillow or appropriate padding under the patient's shoulders and upper back to allow for comfortable hyperextension of the neck. Identify by palpation the thyroid cartilage, laryngeal prominence (Adam's apple), cricoid cartilage, and cricothyroid membrane. These are the anatomic landmarks that will be used to identify the proper site for performing the procedure.

Catheter‐Through‐the-Needle Technique

The operator should follow universal precautions with the use of a mask, eye protection, a sterile gown, and sterile gloves. Using sterile technique, prepare the equipment. Draw 3 to 5 mL of sterile and preservative-free normal saline solution into a 30 mL syringe with a sterile needle. Attach an appropriately sized needle from a catheter-through-the-needle set (18 to 20 gauge for an adult, 20 to 22 gauge for a child) to a 3 mL syringe. An alternative technique is to draw up 1 to 2 mL of sterile saline into the syringe before attaching the catheter-through-the-needle. Draw up 1 to 3 mL of local anesthetic solution into a 3 mL syringe armed with a 25 to 27 gauge needle.

Position the patient as noted above. Using sterile technique, prepare the neck. Clean the anterior neck of any dirt and debris. Apply povidone iodine or chlorhexidine solution and allow it to dry. Place sterile towels or a sterile drape to isolate the anterior neck. Palpate the anterior neck and reidentify the thyroid cartilage, laryngeal prominence, cricoid cartilage, and cricothyroid membrane. Leave the nondominant index finger over the cricothyroid membrane for reference.

Apply a small subcutaneous wheal of local anesthetic solution below the skin at the anterior midpoint of the cricothyroid membrane (Figure 28-2). Inject 0.5 to 1.0 mL of local anesthetic solution into the subcutaneous tissues down to the level of the cricothyroid membrane, taking care not to distort the anatomy. Reidentify the cricothyroid membrane by palpation. Insert the needle on the syringe, directed caudally and at a 30° to 45° angle to the skin (Figure 28-3). Continue to advance the needle while applying negative pressure to the syringe (Figure 28-3A). Stop advancing the needle when air is aspirated into the syringe. This signifies that the needle is inside the trachea. If using a saline filled syringe, air bubbles will be clearly visible within the saline. Hold the needle securely and remove the syringe. Insert the catheter through the needle (Figure 28-3B). While holding the catheter securely, withdraw the needle until the tip has exited the skin of the neck (Figure 28-3C). Place the needle guard over the needle. This will prevent shearing off of the catheter. Apply the 30 mL syringe containing saline to the catheter (Figure 28-3C).

Ask the patient to cough if they are not already doing so. Aspirate with the 30 mL syringe as the patient coughs. If no specimen is obtained, instill the sterile saline. Once again, ask the patient to cough if not stimulated by the saline. Aspirate until a specimen is acquired. An alternative to using a large syringe for aspiration is the use of low wall suction and a Lukens tube or a similar trap device to collect the specimen.

Remove the catheter, needle, and syringe as one unit. Hold direct pressure on the puncture site for 3 to 5 minutes. Apply a bandage or sterile dressing to the puncture site. Place the specimen in a sterile container and have it transported to the laboratory.

Many physicians are reluctant to use the catheter-through-the-needle system as there is the possibility of shearing off the catheter within the trachea. This can be prevented by applying the needle guard over the needle immediately after it is withdrawn from the skin.

Catheter‐Over‐the-Needle Technique

The more commonly used technique is to use a catheter-over-the-needle (angiocatheter) system (Figure 28-4). The operator should follow universal precautions. Cleanse, prepare, and anesthetize the patient as above.

Using sterile technique, prepare the equipment. Draw 3 to 5 mL of sterile and preservative-free normal saline solution into a 30 mL syringe with a sterile needle. Attach an appropriately sized catheter-over-the-needle (18 to 20 gauge for an adult, 20 to 22 gauge for a child) to a 3 mL syringe. An alternative technique is to draw up 1 to 2 mL of sterile saline into the syringe before attaching the catheter-over-the-needle. Draw up 1 to 3 mL of local anesthetic solution into a 3 mL syringe armed with a 25 to 27 gauge needle.

Reidentify the cricothyroid membrane by palpation. Insert the catheter-over-the needle on the syringe, directed caudally and at a 30° to 45° angle to the skin (Figure 28-4A). Continue to advance the catheter-over-the-needle while applying negative pressure to the syringe. Stop advancing the catheter-over-the-needle as soon as air is aspirated into the syringe. This signifies that the needle is inside the trachea. If using a saline filled syringe, air bubbles will be clearly visible within the saline (Figure 28-4B). Hold the syringe securely and advance the catheter until its hub is against the skin (Figure 28-4C). Remove the needle and syringe. Apply the 30 mL syringe containing saline to the catheter (Figure 28-4D).

Ask the patient to cough if they are not already doing so. Aspirate with the 30 mL syringe as the patient coughs. If no specimen is obtained, instill the sterile saline. Once again, ask the patient to cough if not stimulated by the saline. Aspirate until a specimen is acquired. An alternative to using a large syringe for aspiration is the use of low wall suction and a Lukens tube or a similar trap device to collect the specimen.

Remove the catheter. Hold direct pressure on the puncture site for 3 to 5 minutes. Apply a bandage or sterile dressing to the puncture site. Place the specimen in a sterile container and have it transported to the laboratory.

The patient should be observed for bleeding at the puncture site, the development of subcutaneous emphysema, any changes in sputum production, or hemoptysis. Obtain a chest radiograph immediately after the procedure to look for subcutaneous air and/or a pneumothorax.

The patient should remain on continuous pulse oximetry to monitor possible deterioration in respiratory status. Obtain a chest radiograph in 24 hours to look for subcutaneous air and/or a pneumothorax. Any procedure that might stimulate coughing should be avoided for at least 24 hours.

The complications range from minimal hemoptysis and localized subcutaneous emphysema to massive pulmonary hemorrhage and death.8–13 Minimal hemoptysis was seen in 15% of pediatric patients in one study and commonly in several adult studies. Localized subcutaneous emphysema in the anterior neck occurred in 5% to 18% of patients. There are rare reports of fatal endotracheal hemorrhage, profound coughing with development of massive subcutaneous and mediastinal emphysema, vomiting and aspiration of gastric contents, cardiac dysrhythmias, and sudden cardiac death. There is at least one case of fatal gastrointestinal hemorrhage from ruptured esophageal varices and Mallory–Weiss tears following “unrestrainable” coughing.

Transtracheal aspiration is a useful technique for obtaining uncontaminated specimens for analysis and culture. The procedure is best used in those patients who have complicated courses or are failing to respond to appropriate treatment or when there is a high index of suspicion for aspiration pneumonia and more atypical infectious agents.