Specimen Collection: Sputum by Suction (Respiratory Therapy)

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    Specimen Collection: Sputum by Suction (Respiratory Therapy)


    If the patient develops respiratory distress during the suctioning procedure, immediately withdraw the catheter and supply additional oxygen and ventilatory breaths as needed.


    Sputum is produced by cells lining the respiratory tract. It is normal for healthy lungs to produce sputum, but certain conditions can change the characteristics of sputum or increase the amount of sputum produced. A sputum specimen collection may be necessary for laboratory testing. Sputum specimen collection should be performed using proper sterile technique so that the sputum specimen is uncontaminated.

    The most common reason to obtain a sputum specimen is for a microscopic examination using a direct smear and culture and sensitivity. The direct smear uses a staining method that helps determine the type or shape of microorganism in the specimen. The culture and sensitivity test identifies specific microorganisms that cause the respiratory infection and helps to determine the most effective antibiotic treatment.undefined#ref5">5

    A sputum specimen should be obtained from the lower airways. Suction should be performed through the nose (nasotracheal suctioning) if the patient does not have an artificial airway. Use of a nasopharyngeal airway should be considered to reduce mucosal trauma and lessen the risk of cross contamination from the nasal passage. If an artificial airway is already present, suction should be performed through the existing artificial airway (endotracheal or tracheostomy tube suctioning).

    The two techniques used for suctioning include the open suction method (Figure 1)Figure 1, which uses a single-use open catheter primarily on patients who do not have an artificial airway, and the closed suction method (Figure 2)Figure 2, which uses a sterile sleeved closed catheter (or inline suction) for patients with an artificial airway, who may also be on a mechanical ventilator. The closed suction method (or inline suction) is preferable for patients who are being mechanically ventilated because it does not require the mechanical ventilator to be disconnected. Disconnecting the mechanical ventilator may lead to lung derecruitment and hypoxemia and risk of cross-contamination.1

    Generally, suctioning is well tolerated with minor discomfort and adverse reactions; however, there are risks associated with suctioning. The most serious risks are related to hypoxemia. Hypoxemia and vagal nerve stimulation of the airway can result in cardiac arrhythmias, laryngeal spasm, bradycardia, and hypotension.4 Other risks include trauma and bleeding caused by the suction catheter.


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    • Provide developmentally and culturally appropriate education based on the desire for knowledge, readiness to learn, and overall neurologic and psychosocial state.
    • Explain to the patient and family that suctioning is needed to obtain the sputum specimen.
    • Explain that temporary coughing, tearing, sneezing, gagging, or shortness of breath may happen during the procedure.
    • Encourage the patient to cough during the procedure to assist in expelling mucus from the upper airway.
    • Demonstrate splinting technique, if needed.
    • Encourage questions and answer them as they arise.



    1. Perform hand hygiene before patient contact. Don appropriate personal protective equipment (PPE) based on the patient’s need for isolation precautions or the risk of exposure to bodily fluids.
    2. Introduce yourself to the patient.
    3. Verify the correct patient using two identifiers.3
    4. Verify the practitioner’s order for the type of sputum analysis and specifications (e.g., amount of sputum, number of specimens, time of collection, method to obtain).
    5. For the patient without an artificial airway, ensure the patient has not recently eaten or used toothpaste or mouthwash because this may contaminate the sputum specimen.
    6. Determine the type of patient assistance needed to obtain a specimen.
    7. Assess the patient’s vital signs, including oxygen saturation (SpO2), respiratory rate (RR), heart rate (HR), and blood pressure (BP).
    8. Auscultate the patient’s breath sounds before and after the suctioning procedure for sputum specimen collection.


    1. Position the patient in the high Fowler or semi-Fowler position per the patient’s comfort level.
    2. Place a towel or paper drape across the patient’s chest, if needed.
    3. Splint surgical incisions or localized areas of discomfort. Instruct the patient to place hands or a pillow firmly over the area.
    4. If a speaking valve is present, remove it before suctioning.
    5. Prepare the vacuum suction source (wall or portable) and suction tubing to determine proper function.
    6. Set the suction regulator to less than 200 mm Hg for adults2 (no greater than what is required to remove secretions adequately).
    7. Ensure that an oxygen source is available.
    8. Gather additional equipment needed for the sputum specimen collection, including an appropriate-size suction catheter, inline sterile specimen container (sputum trap), and additional PPE as indicated.
    9. If using the closed suction method, connect a new sterile sleeved closed suction catheter to the patient’s artificial airway. Keep the sterile cap on the end until the sputum specimen trap is attached.


    1. Perform hand hygiene and don gloves, gown, mask, and eye protection or face shield.
    2. Verify the correct patient using two identifiers.3
    3. Explain the procedure and ensure that the patient agrees to treatment.
    4. Instruct the patient to breathe normally during suctioning to prevent hyperventilation.
    5. Using aseptic technique, prepare the sputum trap and connect the vacuum suction source tubing to the hard-plastic adapter on the sterile specimen trap.
      Keep the soft-rubber tubing on the specimen trap protected in the packaging to prevent cross contamination.
    6. Using aseptic technique, open and prepare the appropriate-size suction catheter. The suction catheter should occlude less than 70% of the inner diameter of the artificial airway.2
    7. Remove gloves and perform hand hygiene.
    8. Prepare for the sputum specimen collection.
      1. Open suction method
        1. Don sterile gloves prior to sputum collection.
        2. Pick up the sterile suction catheter with the dominant hand without touching any nonsterile surfaces. Pick up the sputum trap with the nondominant hand.
        3. Connect the sterile suction catheter to the soft-rubber tubing on the sputum trap (Figure 1)Figure 1.
      2. Closed (inline) suction method
        1. Don nonsterile gloves prior to sputum collection.
        2. Remove the sterile cap from the end of the closed suction catheter without allowing the end of the catheter to touch any nonsterile surfaces. Pick up the sputum trap.
        3. Connect the closed suction catheter to the soft-rubber tubing on the sputum trap (Figure 2)Figure 2.
          If using the closed suction method (Figure 2)Figure 2, ensure that the sleeved suction catheter is new and uncontaminated.
    9. Preoxygenate the patient for 30 to 60 seconds.1,4
    10. Gently insert the tip of the suction catheter through the nasopharynx, nasopharyngeal tube, endotracheal tube, or tracheostomy tube without applying suction.
      Rationale: Inserting the catheter without applying suction minimizes hypoxemia and trauma to the airway as the catheter is inserted.
    11. Advance the catheter into the nasopharynx, nasopharyngeal tube, endotracheal tube, or tracheostomy tube gently and quickly. Only advance the catheter to the end of the endotracheal or tracheostomy tube.
      Rationale: Entrance of the catheter into the larynx and trachea usually triggers the cough reflex.
    12. As the patient coughs, apply suction and gently withdraw the catheter. Limit the aspiration time to 15 seconds or less.2,4 Apply suction by placing the thumb of the nondominant hand over the suction port of the regular suction catheter or by depressing the suction button of the sleeved suction catheter.
      Suctioning longer than 15 seconds can cause hypoxia and mucosal damage.2,4
      If the patient shows signs of becoming hypoxemic during the procedure, discontinue the procedure immediately and provide oxygen as ordered.
    13. Release suction and completely remove the catheter from the nasopharynx, nasopharyngeal tube, endotracheal tube, or tracheostomy tube.
    14. Reoxygenate the patient and allow a short rest period for the patient to catch the breath and for oxygenation to return to baseline.
    15. Continue the procedure until enough of a specimen has been collected.
    16. Detach the catheter from the specimen trap.
      1. If using a sterile open suction catheter, dispose of it in the appropriate receptacle.
      2. If using a sleeved closed suction catheter, reconnect the vacuum suction tubing to the end of the closed suction catheter.
    17. Prepare the sputum specimen for laboratory testing.
      1. Detach the vacuum suction tubing from the hard-plastic sputum trap and connect the soft-rubber tubing to the hard-plastic adapter.
      2. Secure the top of the specimen container tightly.
      3. In the presence of the patient, label the specimen per the organization’s practice.3
      4. Place the labeled specimen in a biohazard bag and transport it to the laboratory immediately per the organization’s practice.
    18. Discard supplies, remove PPE, and perform hand hygiene.
    19. Document the procedure in the patient’s record.


    1. Monitor the patient’s response to the procedure, including vital signs and any adverse effects.
    2. Inspect the consistency, amount, and color of the sputum specimen.
    3. Reassess breath sounds.
    4. Observe the patient for anxiety. Reassure the patient.
    5. Observe the patient for signs and symptoms of pain. If pain is suspected, report it to the authorized practitioner.


    • Vital signs, including HR, RR, BP, and SpO2, return to baseline.
    • Oxygenation status is not compromised.
    • Adequate amount of sputum is collected.
    • Sputum specimen is not contaminated.


    • Hypoxemia
    • Increased respiratory rate and effort
    • Shortness of breath
    • Anxiety
    • Inadequate amount of sputum collected
    • Contaminated sputum specimen
    • Pain or discomfort


    • Method used to obtain specimen
    • Preoxygenation steps
    • Date and time of collection
    • Characteristics of sputum specimen, including amount, color, and consistency
    • Vital signs, including HR, RR, BP, and SpO2
    • Breath sounds
    • Patient’s tolerance of procedure
    • Education
    • Unexpected outcomes and related interventions


    1. American Association for Respiratory Care (AARC). (2010). AARC clinical practice guidelines: Endotracheal suctioning of mechanically ventilated patients with artificial airways 2010. Respiratory Care, 55(6), 758-764. (classic reference)* (Level VII)
    2. Blakeman, T.C. and others. (2022). AARC clinical practice guidelines: Artificial airway suctioning. Respiratory Care, 67(2), 258-271. doi:10.4187/respcare.09548 (Level VII)
    3. Joint Commission, The. (2023). National Patient Safety Goals for the hospital program. Retrieved April 20, 2023, from (Level VII)
    4. La Vita, C.J. (2021). Chapter 37: Airway management. In R.M. Kacmarek, J.K. Stoller, A.J. Heuer (Eds.), Egan’s fundamentals of respiratory care (12th ed., pp. 748-787). St. Louis: Elsevier.
    5. Prestholdt, F.J. (2022). Chapter 7: Clinical laboratory studies. In A.J. Heuer (Ed.), Wilkins’ clinical assessment in respiratory care (9th ed., pp. 117-140). St. Louis: Elsevier.

    *In these skills, a “classic” reference is a widely cited, standard work of established excellence that significantly affects current practice and may also represent the foundational research for practice.

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