Airway Clearance Techniques
I Definition: Airway clearance techniques include the use of invasive and noninvasive therapy to help mobilize and remove secretions and improve gas exchange.
II Airway Clearance Physiology
A Normal airway clearance (see Chapter 4)
1. Normal clearance of the airway depends on a patent airway, a functional mucociliary transport system, and an effective cough.
2. The mucociliary transport system functions from the larynx down to the respiratory bronchioles.
3. Goblet cells and submucosal glands are responsible for the majority of secretions in the central airways.
4. Ciliated epithelial cells in a coordinated wavelike motion move mucus toward the trachea and larynx where it can be swallowed or expectorated.
5. The normal respiratory tract produces approximately 100 ml of mucus per day.
B Four phases of normal cough reflex (Figure 36-1)
a. Inflammatory, mechanical, chemical, or thermal stimulus trigger airway sensory receptors, sending impulses to the brain’s medullary cough center.
a. In response to these afferent impulses the cough center reflexively stimulates the inspiratory muscles to initiate a deep inspiration.
1. Airway abnormalities that alter airway patency, mucociliary transport, or cough reflex may impede airway clearance and cause retention of secretions.
2. Mucous plugging can cause complete obstruction of the airway, resulting in atelectasis and impaired gas exchange because of shunting.
3. Partial obstruction from retained secretions restricts airflow, causing increased work of breathing, air trapping, overdistention, and ventilation/perfusion (
/
) mismatch.
4. Infectious processes caused by microorganisms in retained secretions cause an inflammatory response and the release of chemical mediators, resulting in increased mucus production.
5. Causes of impaired mucociliary transport in intubated patients
III Methods to Manage Thick Secretions
1. Bland aerosol therapy can be used for the management of thick, tenacious secretions in patients who have intact upper airways.
2. However, no studies have reported a benefit from external humidification in improving the character or mobilization of thick secretions.
3. Systemic hydration is the most effective method to improve the character of pulmonary secretions.
a. Approved for the management of cystic fibrosis
b. Delivered to the airway via small volume nebulizer
c. Efficacy not proven for acute exacerbations of cystic fibrosis or for the management of other chronic airway diseases
a. Delivered to the airway via small volume nebulizer or instillation into artificial airway
b. Has never been approved for inhalation
c. Few or no data to support its efficacy when nebulized
d. Can irritate the airway and induce bronchospasm
e. Effective when instilled into specific lung segments during bronchoscopy
A Suctioning through an artificial airway
b. Wheezing, rhonchi, or rales or decreased breath sounds
c. Unexplained increases in ventilator pressure during volume ventilation or decreases in tidal volume during pressure control ventilation
2. Sterile technique must be used when suctioning an artificial airway, except when an in-line suction catheter is used.
3. Preoxygenation can help minimize hypoxemia caused by suctioning.
4. The suction catheter should not remain in the airway for >15 seconds.
5. Sterile saline should not routinely be instilled into the airway. There is no evidence that this practice increases the amount of secretions removed from the airway, and it may worsen oxygenation. Sterile saline should only be used to help loosen exceptionally thick and tenacious secretions encountered during suctioning.
1. Patients with excessive secretions and a poor cough reflex may benefit from nasotracheal suctioning.
2. Placement of a nasopharyngeal airway may help to reduce trauma to the nasal passage from repeated suctioning.
a. Inability to clear secretions
b. Audible evidence of secretions in the large/central airways that persist despite patient’s best cough effort
1. Therapeutic bronchoscopy is used for the removal of foreign bodies from the airway, management of focal atelectasis, and airway occlusion caused by retained secretions.
2. There is limited evidence that routine bronchoscopy for removal of retained secretions provides any greater benefit than suctioning and chest physiotherapy techniques.
3. Bronchoscopy is beneficial for the removal of secretions from the airway for diagnostic testing purposes.
V Noninvasive Bronchial Hygiene
1. Postural drainage is a method of removing pooled secretions by positioning the patient to allow gravity to assist in movement of secretions. The patient should be positioned so that the affected lung segments are superior to the carina, with each position maintained for 3 to 15 minutes.
2. Indications (Modified from AARC Clinical Practice Guideline: Postural Drainage, 1991)
a. Inability or reluctance of patient to change body position
b. Poor oxygenation associated with position (e.g., unilateral lung disease)
c. Potential for or presence of atelectasis
d. Presence of artificial airway
e. Evidence or suggestion of difficulty with secretion clearance
f. Difficulty clearing secretions, with expectorated sputum production >25 to 30 ml/day (for an adult)
g. Evidence or suggestion of retained secretions in the presence of an artificial airway
h. Presence of atelectasis caused by or suspected of being caused by mucous plugging
i. Diagnosis of diseases such as cystic fibrosis, bronchiectasis, or cavitating lung disease
j. Presence of foreign body in airway
k. External manipulation of the thorax: Sputum volume or consistency suggesting a need for additional manipulation
3. Contraindications (Modified from AARC Clinical Practice Guideline: Postural Drainage, 1991)
a. The decision to use postural drainage therapy requires assessment of potential benefits versus potential risks. Therapy should be provided for no longer than necessary to obtain the desired therapeutic results. Listed contraindications are relative unless marked as absolute (A).
b. Positioning: All positions are contraindicated for
(1) Head and neck injury until stabilized (A)
(2) Active hemorrhage with hemodynamic instability (A)
(4) Recent spinal surgery or acute spinal injury
(8) Pulmonary edema associated with congestive heart failure
(9) Aged, confused, or anxious patients who do not tolerate position changes
(11) Rib fracture, with or without flail chest
c. Trendelenburg position is contraindicated for
(1) Recent gross hemoptysis related to recent lung carcinoma managed surgically or with radiation therapy
(5) Patients in whom increased ICP is to be avoided (e.g., neurosurgery, aneurysms, or eye surgery)
(6) Uncontrolled airway at risk for aspiration (e.g., tube feeding or recent meal)
d. External manipulation of the thorax (in addition to contraindications previously listed)
4. Hazards and complications (Modified from AARC Clinical Practice Guideline: Postural Drainage, 1991)
5. Standard postural drainage positions for each of the lung segments
a. Apical segments of right and left upper lobes: Patient in semi-Fowler’s position with head of the bed raised 45 degrees (Figure 36-2).
b. Anterior segments of both upper lobes: Patient supine with the bed flat (Figure 36-3).
c. Posterior segments of right upper lobe: Patient one-quarter turn from prone with the right side up, supported by pillows, and with head of the bed flat (Figure 36-4).
d. Apical-posterior segment of left upper lobe: Patient one-quarter turn from prone with the left side up, supported by pillows, and with head of the bed elevated 30 degrees (Figure 36-5).
e. Medial and lateral segments of right middle lobe: Patient one-quarter turn from supine with right side up and foot of the bed elevated 12 in. (Figure 36-6).
f. Superior and inferior segments of lingula: Patient one-quarter turn from supine with left side up and foot of the bed elevated 12 in. (Figure 36-7).
g. Superior segments of both lower lobes: Patient prone with head of the bed flat and pillow under the abdominal area (Figure 36-8).
