13.2 Airway Clearance Techniques & Breathing Exercises

13.2 Airway Clearance Techniques & Breathing Exercises

[!NOTE] DHA Clinical Examination Benchmark: Mastery of airway clearance techniques (ACTs), chest physiotherapy, and therapeutic breathing exercises is a core testing domain on the DHA Physiotherapist licensing examination. Candidates must know the precise anatomical drainage postures for individual bronchopulmonary segments, absolute contraindications to head-down Trendelenburg positioning, the mechanical physics of collateral ventilation (Pores of Kohn), the operational differences between Flutter and Acapella oscillating PEP devices, and the Equal Pressure Point (EPP) theory governing pursed-lip breathing in obstructive lung disease.

Effective airway clearance is vital for preventing mucus plugging, atelectasis, secondary bacterial colonization, and respiratory failure in patients with bronchiectasis, cystic fibrosis, chronic bronchitis, and post-thoracoabdominal surgery.

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1. Postural Drainage (PD) Anatomy & Positional Guidelines

Postural drainage utilizes gravity to transport secretions from peripheral bronchopulmonary segments toward the central segmental, lobar, and mainstem bronchi, where they can be evacuated via coughing or suctioning.

+-----------------------------------------------------------------------------------+
|              Postural Drainage Positions for Bronchopulmonary Segments            |
+-----------------------------------------------------------------------------------+
| UPPER LOBES:                                                                      |
| 1. Apical Segments: Seated upright or leaning back 30-40°.                        |
|    - Percussion: Directly between the clavicle and top of scapula bilaterally.   |
| 2. Posterior Segment (Right): Prone, turned 1/4 onto left side, head/shoulders    |
|    elevated 45° on pillows. Percussion: Over right upper posterior back.          |
| 3. Posterior Segment (Left): Seated leaning forward 30-40° over a table/pillow.   |
|    - Percussion: Over left upper posterior thoracic wall above spine of scapula.  |
| 4. Anterior Segments (Bilateral): Supine flat, pillow under knees for comfort.    |
|    - Percussion: Directly between clavicles and nipples on both sides.            |
+-----------------------------------------------------------------------------------+
| MIDDLE LOBE & LINGULA (Requires 15° Trendelenburg / Bed Elevated 12-15 Inches):    |
| 5. Right Middle Lobe (Medial & Lateral): Supine, rotated 1/4 onto left side,      |
|    right arm raised. Percussion: Between right axilla and right nipple.           |
| 6. Lingular Segment (Left Upper Lobe): Supine, rotated 1/4 onto right side,       |
|    left arm raised. Percussion: Between left axilla and left nipple.              |
+-----------------------------------------------------------------------------------+
| LOWER LOBES - SUPERIOR SEGMENTS (Flat Bed):                                       |
| 7. Superior (Apical) Segments: Prone flat, pillow under abdomen/pelvis.           |
|    - Percussion: Over middle posterior back, directly below inferior scapular angle|
+-----------------------------------------------------------------------------------+
| LOWER LOBES - BASAL SEGMENTS (Requires 30° Trendelenburg / Bed Elevated 18 Inches):|
| 8. Anterior Basal Segments: Supine flat, knees flexed over pillow.                |
|    - Percussion: Over anterior lower rib margin (ribs 7-9) bilaterally.           |
| 9. Posterior Basal Segments: Prone flat, pillow under hips.                       |
|    - Percussion: Over posterior lower ribs adjacent to thoracic spine.            |
| 10. Lateral Basal Segments: Side-lying on contralateral side (drain right -> lie  |
|     on left; drain left -> lie on right). Percussion: Over lower lateral ribcage. |
+-----------------------------------------------------------------------------------+

Segmental Drainage Protocol Summary

Non-Negotiable Contraindications to Postural Drainage & Trendelenburg

Postural drainage positions that utilize the head-down (Trendelenburg) position carry severe hemodynamic and mechanical hazards:

+-----------------------------------------------------------------------------------+
|             CONTRAINDICATIONS TO HEAD-DOWN TRENDELENBURG POSITIONING              |
+-----------------------------------------------------------------------------------+
| 1. Increased Intracranial Pressure (ICP > 20 mmHg) or Acute Intracranial Injury   |
| 2. Uncontrolled Severe Systemic Hypertension (Resting BP >180/110 mmHg)           |
| 3. Acute Congestive Heart Failure / Frank Pulmonary Edema (Cardiac Overload)     |
| 4. Severe Gastroesophageal Reflux Disease (GERD) or Recent Tube Feeding (Aspiration)|
| 5. Recent Esophageal Anastomosis or Recent Thoracoabdominal Surgery               |
| 6. Acute Gross Hemoptysis (Active pulmonary hemorrhage)                           |
| 7. Massive Distended Abdomen, Ascites, or Recent Meal (<1-2 hours)                |
| 8. Aortic Aneurysm or Dissection Risk | Acute Unstable Spinal Injury              |
+-----------------------------------------------------------------------------------+

[!CAUTION] Clinical Adaptation: When treating a patient with lower lobe basal secretions who has a strict contraindication to Trendelenburg (e.g., severe GERD or elevated ICP), the therapist must modify the position by placing the patient flat (horizontal) in side-lying or prone. Never place an at-risk patient into head-down tilt!

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2. Manual Chest Physical Therapy: Percussion & Vibration

Manual chest physical therapy techniques are applied in conjunction with postural drainage positioning to loosen tenacious secretions from the bronchial tree.

Percussion (Chest Clapping)

• Technique: The therapist rhythmically claps the patient's thoracic wall over the targeted bronchopulmonary segment using cupped hands. The cupping forms an enclosed air cushion between the palm and chest wall, producing a hollow, drum-like "popping" sound. The trapped air cushion generates kinetic energy and acoustic shock waves that transmit through the chest wall and pleural space into the pulmonary parenchyma, shearing mucus from airway walls.
• Parameters: Applied rhythmically at a cadence of 100 to 480 claps per minute for 3 to 5 minutes per segment. The therapist's wrists and elbows remain relaxed, generating force through forearm and shoulder oscillation.
• Absolute & Relative Contraindications to Percussion:
  • Flail chest, rib fractures, or severe chest wall trauma.
  • Severe osteoporosis or prolonged systemic corticosteroid use.
  • Severe bleeding disorders (coagulopathy, Thrombocytopenia with platelet count <50,000/µL, or elevated INR >2.5–3.0).
  • Directly over skin grafts, open wounds, healing burns, or chest incisions.
  • Directly over subcutaneous emphysema.
  • Directly over pacemaker generators, internal cardiac defibrillators (ICDs), or thoracic drainage tubes.
  • Metastatic bone cancer involving the ribs or vertebral column.

Vibration and Shaking

• Technique: Manual vibration involves the application of a fine, rapid, oscillatory compressive movement to the chest wall. The therapist places both hands flat over the affected segment, co-contracts the shoulder and arm musculature, and applies downward gentle chest compression strictly during the exhalation phase of breathing.
• Prerequisite: Vibration must be preceded by a deep inspiration to ensure sufficient expiratory volume and airflow velocity to transport mobilized secretions.
• Shaking: A coarser, more vigorous bouncing oscillatory force applied to the chest wall during exhalation, often used in large, dense adult patients.

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3. The Active Cycle of Breathing Technique (ACBT)

The Active Cycle of Breathing Technique (ACBT) is a flexible, patient-directed airway clearance regimen that mobilizes secretions without inducing severe bronchospasm or oxygen desaturation. It is widely used in cystic fibrosis, bronchiectasis, and post-surgical atelectasis.

                      ACTIVE CYCLE OF BREATHING (ACBT)
                                     │
                                     ▼
               ┌───────────────────────────────────────────┐
               │       1. BREATHING CONTROL (BC)           │
               │ - Gentle, relaxed diaphragmatic breathing │
               │ - Normal resting tidal volume             │
               │ - Relaxes shoulders and upper chest       │
               │ - Prevents bronchospasm & desaturation    │
               └─────────────────────┬─────────────────────┘
                                     │
                                     ▼
               ┌───────────────────────────────────────────┐
               │  2. THORACIC EXPANSION EXERCISES (TEE)    │
               │ - 3 to 4 deep, active inspirations        │
               │ - Emphasis on lower thoracic rib expansion│
               │ - 3-second end-inspiratory hold           │
               │   (Recruits Pores of Kohn / collateral air)│
               │ - Passive, unforced exhalation            │
               └─────────────────────┬─────────────────────┘
                                     │
                                     ▼
               ┌───────────────────────────────────────────┐
               │       3. BREATHING CONTROL (BC)           │
               │ - Period of gentle resting recovery       │
               └─────────────────────┬─────────────────────┘
                                     │
                                     ▼
               ┌───────────────────────────────────────────┐
               │ 4. FORCED EXPIRATORY TECHNIQUE (FET/HUFF) │
               │ - 1 to 2 huffs performed with OPEN GLOTTIS│
               │ - Low-to-medium lung volume huff clears   │
               │   peripheral small airways                │
               │ - High lung volume huff clears central    │
               │   large airways into trachea/mouth        │
               └─────────────────────┬─────────────────────┘
                                     │
                                     ▼
               ┌───────────────────────────────────────────┐
               │       5. BREATHING CONTROL (BC)           │
               │ - Final recovery and reassessment         │
               └───────────────────────────────────────────┘

Pathophysiological Principle: Collateral Ventilation

During the Thoracic Expansion Exercise (TEE) phase, instructing the patient to perform a 3-second end-inspiratory hold (apneustic pause) allows air to redistribute behind retained mucus plugs via collateral ventilatory channels:

• Pores of Kohn: Microscopic openings between adjacent alveolar walls.
• Canals of Lambert: Interconnections linking pre-terminal bronchioles directly with neighboring alveoli.
• Channels of Martin: Interbronchiolar anastomoses.

Air entering via these collateral passages builds pressure behind the obstructing mucus plug, which helps push it forward toward the larger airways during the subsequent forced expiratory technique.

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4. Autogenic Drainage (AD)

Autogenic Drainage is an advanced, self-administered airway clearance technique developed by Jean Chevalier that uses controlled airflow velocity at varying lung volumes to shear mucus without creating the dynamic airway collapse seen during violent coughing.

+-----------------------------------------------------------------------------------+
|                       The Three Distinct Phases of AD                             |
+-----------------------------------------------------------------------------------+
| Phase 1: Unsticking (Peripheral Clearance)                                        |
|   - Patient breathes at low lung volume (near Expiratory Reserve Volume [ERV]).   |
|   - Slow, deep inspiration through nose, 2-3s hold, followed by controlled        |
|     exhalation down to low lung volume to loosen secretions in peripheral airways.|
+-----------------------------------------------------------------------------------+
| Phase 2: Collecting (Intermediate Clearance)                                      |
|   - Patient breathes at normal tidal volume (mid-lung volume).                    |
|   - Gathers and mobilizes secretions from peripheral bronchioles into medium-     |
|     sized bronchial branches.                                                     |
+-----------------------------------------------------------------------------------+
| Phase 3: Evacuating (Central Clearance)                                           |
|   - Patient breathes at high lung volume (up to Inspiratory Capacity [IC]).       |
|   - Mobilizes secretions from medium airways into central trachea, culminating in  |
|     a gentle, high-volume huff for expectoration.                                 |
+-----------------------------------------------------------------------------------+

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5. Positive Expiratory Pressure (PEP) & Oscillating PEP (OPEP)

Positive Expiratory Pressure therapy requires the patient to exhale against an expiratory resistor, generating positive intraluminal pressure that stents open collapsible bronchi, recruits collapsed alveoli via collateral channels, and shears secretions cephalad.

+-----------------------------------------------------------------------------------+
|                    Comparison of Leading OPEP Devices                             |
+-----------------------------------------------------------------------------------+
| Feature              | Flutter Device             | Acapella Device               |
+----------------------+----------------------------+-------------------------------+
| Mechanism            | Weighted stainless-steel   | Counterweighted rocker and    |
|                      | ball inside an angled cone | magnet mechanism              |
+----------------------+----------------------------+-------------------------------+
| Operating PEP        | 10 to 25 cmH2O             | 10 to 20 cmH2O (adjustable dial)|
+----------------------+----------------------------+-------------------------------+
| Oscillation Cadence  | 6 to 26 Hz                 | 8 to 18 Hz                    |
+----------------------+----------------------------+-------------------------------+
| Positional Dependence| GRAVITY-DEPENDENT:         | GRAVITY-INDEPENDENT:          |
|                      | Must be held strictly      | Operates at ANY angle or      |
|                      | horizontal or angled up.   | posture: Supine, Side-lying,  |
|                      | CANNOT be used in supine!  | Trendelenburg, or Sitting!    |
+----------------------+----------------------------+-------------------------------+
| Models Available     | Single universal unit      | Green (high flow >15 L/min)   |
|                      |                            | Blue (low flow <15 L/min)     |
+----------------------+----------------------------+-------------------------------+

Clinical Execution of OPEP Therapy

1. Patient sits upright (or in drainage posture if using Acapella), seals lips around mouthpiece, and inhales through the nose to about 75% of vital capacity.
2. Performs a 2 to 3-second end-inspiratory hold.
3. Exhales actively (not forcefully) through the device for 3 to 4 seconds, maintaining an expiratory pressure of 10 to 20 cmH2O.
4. Repeats for 10 to 15 breaths, followed by breathing control and 2 huffs (FET) to expectorate.

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6. Directed Cough vs. Huff Cough & Equal Pressure Point (EPP)

Understanding the biomechanics of coughing is critical for managing patients with floppy, unstable airways (COPD, emphysema, bronchiectasis).

                        THE EQUAL PRESSURE POINT (EPP) THEORY

   ALVEOLI               SMALL NON-CARTILAGINOUS            LARGE CARTILAGINOUS
 (Peripheral)                   AIRWAYS                           AIRWAYS
     │                             │                                 │
  [ P_alv ]  ───────────>   [ Intraluminal P ]  ───────────>    [ Central P ]
     ▲                             │                                 │
     │                             ▼                                 │
 Pleural P                   EPP: Intraluminal P                     │
 (Elevated in               = Pleural Pressure                       │
  Hard Cough)                      │                                 │
     │                             ▼                                 │
     └─────────────────> DYNAMIC COMPRESSION <───────────────────────┘
                         In COPD/Emphysema: EPP shifts
                         peripherally into floppy airways,
                         causing PREMATURE AIRWAY COLLAPSE
                         and MUCUS TRAPPING!

Mechanics of the Standard Directed Cough

• Inspiratory Phase: Deep inspiration (approximately 60–80% of vital capacity).
• Compressive Phase: Glottic closure accompanied by vigorous isometric contraction of the abdominal wall and internal intercostal muscles, driving intrathoracic pleural pressures above 100 to 200 cmH2O.
• Expulsive Phase: Sudden, explosive opening of the vocal cords, producing high-velocity airflow shearing secretions from central airways.

Why Directed Coughing Fails in COPD (The EPP Trap)

The Equal Pressure Point (EPP) is the anatomical location along the airway where the pressure inside the airway lumen exactly equals the surrounding intrathoracic pleural pressure. Downstream from the EPP (toward the mouth), pleural pressure exceeds intraluminal pressure, causing dynamic airway compression. In normal lungs, the EPP occurs within large, rigid, cartilaginous bronchi that resist collapse. In patients with COPD and emphysema who have lost alveolar elastic recoil, high pleural pressures generated during a hard cough shift the EPP peripherally into small, non-cartilaginous, floppy bronchioles, causing immediate dynamic collapse, paroxysmal coughing spasms, severe bronchospasm, and mucus trapping.

The Huff Cough (Forced Expiratory Technique)

In contrast, the Huff Cough is performed with an open glottis (the patient imagines fogging a mirror or saying "ha-ha-ha"). Because the glottis remains open, intrathoracic pleural pressure rises moderately rather than excessively, stabilizing the EPP within central cartilaginous airways, preventing peripheral airway collapse, reducing energy expenditure, and clearing secretions.

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7. Therapeutic Breathing Exercises

Pursed-Lip Breathing (PLB)

• Target Population: Chronic Obstructive Pulmonary Disease (COPD), emphysema, dynamic hyperinflation.
• Technique: The patient inhales slowly through the nose with mouth closed for 2 counts, purses their lips as if whistling or gently blowing out a candle flame, and exhales slowly and passively through pursed lips for 4 to 6 counts (inspiratory-to-expiratory ratio of 1:2 to 1:3).
• Biomechanical Mechanism: Pursed lips create an adjustable expiratory resistance at the mouth. This creates positive backpressure throughout the tracheobronchial tree during expiration, shifting the Equal Pressure Point centrally toward larger, cartilaginous airways. This prevents premature dynamic collapse of terminal bronchioles, facilitates more complete alveolar emptying, reduces dynamic hyperinflation (air trapping), lowers respiratory rate, and increases SpO2.

Diaphragmatic Breathing (Abdominal Breathing)

• Technique: Patient is placed in semi-Fowler's position with knees flexed over pillows. The clinician places one hand over the mid-epigastrium and one hand over the upper sternum. The patient is instructed to inhale deeply through the nose, causing the abdominal hand to rise outwards while the chest hand remains quiet, followed by a relaxed, passive exhalation.
• Indications: Used to decrease the metabolic work of breathing, reduce excessive recruitment of scalene and sternocleidomastoid accessory muscles, improve lower lung base ventilation, and promote autonomic relaxation.

Segmental Breathing (Localized Chest Expansion)

• Technique: Targeted tactile facilitation directed over specific hypoventilated lung areas (apical, lateral costal, or posterior basal). The therapist places their hands firmly over the target rib segment. At the end of exhalation, the therapist applies a quick stretch down and inward to stimulate muscle spindle stretch receptors of the external intercostals, followed by resisting inspiration as the patient expands against the clinician's hands.
• Indications: Asymmetrical atelectasis, post-thoracotomy recovery, pleural adhesion remodeling.

Incentive Spirometry (Sustained Maximal Inspiration, SMI)

• Clinical Purpose: Primary prevention and reversal of acute post-operative atelectasis following upper abdominal or thoracic surgery.
• Technique: Upright sitting position. The patient forms a tight seal around the mouthpiece, exhales normally, and performs a slow, deep, continuous inspiration to Total Lung Capacity (TLC), tracking visual biofeedback (volume or flow target). At peak inspiration, the patient performs a 3 to 5-second end-inspiratory hold, followed by relaxed exhalation.
• Prescription Dosage: 10 sustained maximal breaths every waking hour.

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8. Clinical Scenarios & DHA Exam Traps

Clinical Scenario: Post-Operative Airway Clearance

A 52-year-old male with a history of bronchiectasis undergoes an open partial gastrectomy. On post-operative day 2, he develops coarse crackles over the left lateral basal segment, accompanied by thick secretions, a low-grade fever (38.1°C), and SpO2 of 91% on room air. The surgeon requests chest physiotherapy. When reviewing the chart, the physical therapist notes that the patient has severe active gastroesophageal reflux disease and a nasogastric tube to suction.

• Clinical Decision: Draining the left lateral basal segment normally requires right side-lying with the foot of the bed elevated 18 inches (30° Trendelenburg). However, the patient's acute abdominal surgery and severe GERD make head-down positioning hazardous due to the high risk of gastric reflux and aspiration.
• Physiotherapy Intervention: The therapist positions the patient flat in right side-lying (no Trendelenburg tilt), applies gentle manual vibration during exhalation, trains the patient in the Active Cycle of Breathing Technique (using supported incision splinting with a pillow), and instructs him to perform low-volume huffs to clear secretions safely.

DHA Exam Traps to Avoid

• Trap 1: Flutter vs. Acapella in Bed-Bound Patients: When a clinical scenario asks which oscillating PEP device to prescribe for a patient who cannot sit up and must remain supine or in side-lying, selecting the Flutter device is incorrect. The Flutter device is strictly gravity-dependent and will not oscillate unless held horizontal or tilted upward. The Acapella utilizes a counterweighted rocker and magnet, functioning reliably in any patient position.
• Trap 2: Directed Hard Coughing in Emphysema: If asked how to clear secretions in a patient with severe COPD and emphysema who is exhausted from coughing, never recommend "take a maximal inspiration, close the vocal cords, and cough as hard as possible." Hard coughing shifts the Equal Pressure Point into floppy non-cartilaginous airways, causing immediate airway collapse and mucus trapping. The correct answer is the Forced Expiratory Technique (Huff cough).
• Trap 3: Incentive Spirometry Rate: DHA questions often test the correct execution of incentive spirometry. An answer indicating "inhale as fast and forcefully as possible 30 times in 2 minutes" is dangerous and incorrect. Rapid forceful inhalation causes turbulence, hyperventilation, and dizziness; the technique must be a slow, sustained inspiration with a 3–5 second hold, performed 10 times per hour.