Transtracheal aspiration
Objectives: Aetiological diagnosis of lower respiratory tract infection by microscopic examination and culture of "transtracheal" sputum. Isolated pathogenic bacteria will be tested for antibiotic susceptibility. The specimen is uncontaminated by oropharyngeal organisms.
This type of collection should only be performed if: the expectorated sputum is unrevealing or confusing, the patient cannot raise sputum, or the patient is likely to be infected with anaerobic bacteria or unusual organisms (immunodeficiency, lung abscess).
Contraindication: Bleeding diathesis, uncontrollable cough, uncooperative patient, untreated hypoxemia.
Specimen: Sputum.
Collection time: Preferably before any antibiotic is prescribed (may not be relevant if fungal or parasitic infection is suspected).
Equipment: Sterile sponge, skin disinfectant, gloves, syringe, needle, lidocaine 1% without epinephrine, Intracath®, syringe, sterile saline, transport container, plaster.
Procedure: 1. The collection should only be done by a physician experienced in the procedure.
2. Locate the cricothyroid space.
3. Put on gloves, disinfect the skin, and drape.
4. Infiltrate the skin with lidocaine in the midline down to the cricothyroid membrane (avoid injecting lidocaine into the trachea).
5. Bevel the Intracath needle on the syringe and hold the needle 1,5 cm from the point to avoid plunging it too deeply.
6. Aim the Intracath needle 45° caudal to the skin and firmly thrust it through the membrane; confirm the position by aspiration of air.
7. Remove the syringe and thread the catheter down into the trachea.
8. Remove the stylet from the catheter, slide the needle out of the trachea over the cannula.
9. Attach the 10 mL syringe to the catheter and aspirate during cough. If the specimen is inadequate or the patient does not cough, inject 2-3 mL of sterile saline and aspirate again.
10. Withdraw the catheter, apply pressure to the puncture site, cover with a plaster, and order bed rest for 8 hours.
Complications: 1. Bleeding into trachea
Aetiology: Bleeding diatheses, entry into infracricoid venous plexus.
Prevention: Check bleeding studies before procedure, ensure puncture is between thyroid and cricoid cartilage.
Treatment: Immediate endotracheal intubation, if ventilation is compromised.
2. Subcutaneous or mediastinal emphysema
Aetiology: Entry of air into subcutaneous tissue or mediastinum through puncture site.
Prevention: Should not be done in patients with uncontrollable cough. Apply pressure to the puncture site for 5 minutes, prescribe bed rest for 8 hours after the procedure.
3. Catheter aspiration
Aetiology: Catheter cut off, when the catheter is pulled back through the needle.
Prevention: Never withdraw the catheter through the needle.
4. Cardiac arrhythmia or arrest
Aetiology: Vagal stimulation in hypoxemic patient.
Prevention: Ensure adequate oxygenation.
Storage: Refrigerated (2-8° C).
Transportation: Preferably in a cooling box (2-8° C), if delayed for more than 2 hours.
Reporting: A culture report will be available in 2-3 days.
Comments: The specimen is uncontaminated by oropharyngeal flora. If Mycobacterium tuberculosis or other fastidious organisms are needed these should be specified on the request form.