Week 9: Airway Clearance Therapy and Cough Physiology (Egan's Ch. 44) - Flashcards

Week 9: Airway Clearance and Cough Physiology — Study Notes (Egan's Ch. 44)

• Concept: Cough reflex and airway clearance are built from a sequence of phases and prerequisites. The quiz questions probe mechanics, clinical implications, assessment criteria, and therapeutic approaches.

Cough reflex: Phases and normal airway clearance prerequisites

• Normal cough reflex includes four sequential phases:
  • 1) Irritation
  • 2) Inspiration
  • 3) Compression
  • 4) Expulsion
  • These are the four numbered phases referenced in questions about normal cough.
• For normal airway clearance, all four components are needed:
  • Patent airway
  • Functional mucociliary escalator
  • Effective cough
  • Normal pulmonary compliance

Provocation and mechanics of coughing

• Cough can be provoked by multiple stimuli, including:
  • Anesthesia
  • Foreign bodies
  • Infection
  • Irritating gases
• During the compression phase of a cough, key events occur:
  • Expiratory muscle contraction
  • Opening of the glottis
  • Rapid drop in alveolar pressure

Mucus plugging and consequences of obstruction

• Retention of secretions (mucus plugging) can lead to:
  • Hypoxemia
  • Atelectasis
  • Shunting

Partial airway obstruction: physiologic effects

• Partial obstruction can cause:
  • Increased work of breathing
  • Air trapping or overdistention
  • (Contested option in questions: increased expiratory flows)
  • Ventilation/perfusion ratio imbalances

Cough and matrix of weakness: abdominal muscles and neuromuscular conditions

• Abdominal muscle weakness affecting cough typically compromises the compression and expulsion phases, making it harder to generate sufficient expiratory effort.
• In neuromuscular disorders with generalized weakness, the cough reflex phases most affected tend to be those requiring strong expiratory effort (compression and expulsion), though questions frame this as a targeted assessment of phases.
• Specific conditions mentioned in questions that impair cough phases include muscular dystrophy, amyotrophic lateral sclerosis (ALS), and cerebral palsy (impinging primarily on motor aspects of coughing).

Mucociliary clearance in intubated patients

• Factors that can impair mucociliary clearance in intubated patients include:
  • Tracheobronchial suctioning
  • Inadequate humidification
  • High inspired oxygen concentrations
• These three are recognized as impairing mucociliary function in the intubated patient (
  2, 3, and 4).
• Potentially, use of respiratory stimulants is not listed as a factor that impairs clearance in this context; stimulants may have different effects on clearance mechanisms.

Drug effects on mucociliary clearance (intubated patients)

• Drug categories that can impair mucociliary clearance include:
  • General anesthetics
  • Opiates
  • Narcotics
  • (Bronchodilators are typically not listed as impairing clearance in the same way; exam options group several categories.)
• The combination most commonly cited in questions is 1, 3, and 4 or similar, reflecting central depressants and opioids as contributors to reduced clearance.

Airway patency and factors affecting clearance

• Conditions that can impair airway patency and/or secretion clearance include:
  • Foreign bodies
  • Tumors
  • Inflammation
  • Bronchospasm
• The net concept: obstruction or inflammatory processes can impede clearance by either narrowings or mucous changes.

Mucociliary clearance: disease states and conditions

• Conditions that alter normal mucociliary clearance commonly include:
  • Cystic fibrosis (CF)
  • Ciliary dyskinesia (primary ciliary dyskinesia)
  • Asthma (airway hyperreactivity) can affect clearance dynamics
• Bronchospasm also influences clearance but is often categorized with obstruction rather than a pure mucociliary defect; exam framing often lists 2, 3, and 4 as changing clearance.

Secretion clearance: impairing factors and cough reflex modifiers

• Conditions impairing secretion clearance by affecting the cough reflex include:
  • Muscular dystrophy
  • Amyotrophic lateral sclerosis (ALS)
  • Cerebral palsy
  • Chronic bronchitis (often classified as secretion overproduction affecting clearance but not always impairing the reflex per se)
• The combination typically cited in exams for impaired cough reflex includes 1, 2, and 4 (excluding chronic bronchitis in some question banks), but an option set may present 1, 2, and 4 as a valid grouping.

Goals of airway clearance therapy (ACT)

• Major aims typically include:
  • Mobilize retained secretions
  • Improve pulmonary gas exchange
  • Reduce the work of breathing
• A common misconception to avoid: ACT is aimed at reversing underlying disease; rather, it supports clearance and gas exchange while the underlying condition is managed.

Volume thresholds and indications for chest physiotherapy

• Sputum production thresholds used in practice to justify chest physiotherapy:
  • Common reference: around 30 {mL/day} as a trigger for more aggressive clearance strategies; other options include 15 {mL/day}, 20 {mL/day}, and 10 {mL/day} depending on context.
• Measuring mucus production volume can involve practical everyday units, such as:
  • 1 ext{ tablespoon} vs 1 ext{ ounce} for coarse assessments of mucus volume.

Chest physical therapy (CPT) and sputum management decisions

• Associated conditions where CPT is especially beneficial include:
  • Chronic obstructive lung disease with higher expected sputum yield
  • Cystic fibrosis or bronchiectasis with mucus plugging and sputum retention
• A general rule discussed in the material: CPT can improve clearance when sputum production exceeds a certain threshold (often cited around 30 mL/day in many curricula).

Preventive uses of airway clearance therapy

• Best-documented preventive uses include:
  • Preventing retained secretions in acutely ill patients
  • Maintaining lung function in people with cystic fibrosis
  • Preventing postoperative pulmonary complications

Postoperative airway clearance assessment and planning

• Postoperative airway clearance planning factors include:
  • Patient’s age and respiratory history
  • Nature and duration of the current surgery
  • Number of prior surgical procedures
  • Type of anesthesia (local vs. general)
• These factors help decide whether a patient needs airway clearance interventions postoperatively and how aggressively to pursue them.

Initial and ongoing assessment: chest physical therapy considerations

• Key assessment domains include:
  • Posture and muscle tone
  • Breathing pattern and ability to cough
  • Sputum production
  • Cardiovascular stability
• A comprehensive assessment considers all four domains to tailor an ACT plan.

Clinical signs indicating retained secretions

• Signs suggesting retained secretions include:
  • Copious sputum production
  • Labored breathing
  • Increased inspiratory and expiratory crackles
    -fever is not a direct, universal marker of retained secretions in this context; fever has broader etiologies and not a specific hallmark of retention alone.

Postural drainage and related airway clearance therapies

• Airway clearance therapies include multiple modalities:
  • Postural drainage and percussion
  • Positive airway pressure (e.g., PEP, oscillatory devices)
  • Percussion, vibration, and oscillation devices
  • Incentive spirometry is primarily a lung expansion technique and is sometimes considered separately from clearance therapies depending on the source; the quiz frames incentive spirometry as a separate item in some questions.
• The concept of gravity-based technique refers to using body position to aid drainage of secretions from various lung segments.

Absolute contraindications to turning (postural drainage) and head-down positioning

• Absolute contraindications to turning/postural drainage commonly include:
  • Head and neck injury (until stabilized)
  • Uncontrolled airway at risk for aspiration
  • Unstable spinal cord injuries
• These contraindications guide when to modify or avoid gravity-assisted clearance.

Modifying head-down positions for specific patients

• You may modify head-down positions in patients with:
  • Unstable blood pressure
  • Cerebrovascular disorders
  • Orthopnea
• The goal is to balance therapeutic benefits with hemodynamic and neurologic safety for the patient.

Coordinating with nursing and postoperative planning

• In preparing a postural drainage schedule for a postoperative patient, key information to obtain from the nurse includes:
  • Patient’s medication schedule
  • (Other options include meal schedule and location of incision; the best practice is to coordinate timing with meds and clinical status to avoid adverse events.)

Quick reference: question topics mapped to core concepts

• Q1–Q2: Normal cough phases; prerequisites for airway clearance
• Q3–Q4: Cough provocation; mechanics of compression phase
• Q5–Q7: Secretion retention consequences; implications of partial obstruction; cough phases affected by abdominal weakness
• Q8–Q9: Neuromuscular causes of cough impairment; factors impairing mucociliary clearance in intubation
• Q10–Q12: Drug effects on clearance; conditions affecting patency and clearance; factors altering clearance (CF, PCD, asthma, etc.)
• Q13–Q14: Secretion-clearance impairment by disease; goals of ACT
• Q15–Q17: Sputum volume thresholds; measures to assess mucus production
• Q18–Q20: Preventive uses; postoperative assessment factors; essential laboratory data
• Q21–Q22: Assessment indices; signs of retained secretions
• Q23–Q25: Definitions of airway clearance therapies; gravity-based techniques
• Q26–Q30: Postural drainage indications and contraindications; arranging postoperative clearance; coordinating with care team

Key takeaways for exam preparation

• Remember the four phases of a normal cough and the three prerequisites for effective airway clearance (patent airway, mucociliary escalator, effective cough, compliant lungs).
• Be able to identify stimuli that provoke coughing and the physiological events during the compression phase (expiratory muscle effort, glottis dynamics, rapid pressure changes).
• Know the consequences of mucus plugging and partial airway obstruction on oxygenation, lung volumes, and ventilation-perfusion matching.
• Recognize how abdominal weakness and neuromuscular disorders alter cough effectiveness and which phases are most affected.
• Understand factors that impair mucociliary clearance in intubated patients (notably suctioning, inadequate humidification, high FiO2) and the drug categories that depress mucociliary function.
• Distinguish which conditions alter mucociliary clearance (CF, ciliary dyskinesia, asthma) and which factors impair the cough reflex (neuromuscular diseases and chronic bronchitis in various contexts).
• Grasp the goals of airway clearance therapy and the clinical thresholds (e.g., sputum volume) used to justify therapy, including typical quantitative cues like around 30 {mL/day} for aggressive clearance, and practical mucus-volume measures such as 1 {tablespoon}.
• Be able to list airway clearance therapies (postural drainage, percussion/vibration/oscillation, positive airway pressure) and understand the role of incentive spirometry as a lung-expansion tool rather than a primary clearance method in some settings.
• Know the key pre- and intraoperative factors when planning postoperative airway clearance (age, respiratory history, nature/duration of surgery, prior procedures, anesthesia type).
• Distinguish absolute contraindications to turning/postural drainage (e.g., head/neck injuries until stabilized, uncontrolled risk of aspiration, unstable spinal injuries) and when to modify head-down positions (e.g., in patients with unstable BP, cerebrovascular issues, orthopnea).
• Emphasize interprofessional communication with nursing to coordinate medication timing, positioning, and clearance schedules postoperatively.

30 ext{ points total}

If you want, I can convert these notes into a condensed summary with only the high-yield items or expand any section with more detail from Egan's Ch. 44 content you have in your course materials.