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Catheter‐Through‐the-Needle Technique
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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.
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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.
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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).
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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.
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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.
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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.
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Catheter‐Over‐the-Needle Technique
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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.
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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.
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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).
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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.
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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.