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AIRWAY CLEARANCE Karen Conyers, BSRT, RRT Airway Clearance Pulmonary Physiology and Development Impaired Airway Clearance Airway Clearance Techniques Therapy Adjuncts PULMONARY PHYSIOLOGY AND DEVELOPMENT Birth Respiratory Function – – Airways – – – Terminal respiratory unit not fully developed Respiratory function performed by alveolar-capillary bed Little smooth muscle Small airway diameter Increased airway resistance Lung compliance – – Incomplete elastic recoil Decreased lung compliance Age 2 Months Alveoli – – – Respiratory muscles – – 24 million alveoli present Alveoli small but fully developed Ability to form new alveoli Underdeveloped accessory muscles Diaphragm is primary muscle of respiration Response to increased ventilatory demands – Respiratory rate increases, not tidal volume Ages 3 to 9 Months Increasing strength – – Baby learns to hold head up, reach for things Upper body strength develops, including accessory muscles for respiration Changes in respiratory function – – – Learns to sit up: rib cage lengthens Greater chest excursion Increased tidal volume Age 4 Years Lung development – – Development of pre-acinar bronchioles and collateral ventilation (pores of Kohn) Development of airway smooth muscle Age 8 Years Continued lung development – – – – Alveolar development complete Alveolar size increases Total lung volume increases 300 million alveoli (increased from 24 million at age 2 months) Adult Lung Gradual loss of volume Loss of elasticity – Environmental effects – – – Decreasing compliance Smoking Air pollution Occupational hazards Disease effects Factors Affecting Airflow Airway resistance Turbulent airflow Airway obstruction Normal Airway Resistance Decreasing cross-sectional area from acinus to trachea causes increased resistance, as airflow moves from small to large airways. Cross-sectional areas: – – – – trachea diameter 4th generation bronchi bronchioles acinus cross-section 2 cm 20 cm 80 cm 400 cm Greatest airway resistance in large airways; laminar airflow in small airways Airway Obstruction Increased airway resistance – – Bronchospasm Inflammation Hypersecretion of mucus – – Acute process Chronic disorder Mucus Mucus produced by goblet cells in airway Chronic airway irritation of goblet cells increased numbers larger quantities of mucus Cilia move together in coordinated fashion to move mucus up airways IMPAIRED AIRWAY CLEARANCE Impaired Airway Clearance: Factors Ineffective mucociliary clearance Excessive secretions Thick secretions Ineffective cough Restrictive lung disease Immobility / inadequate exercise Dysphagia / aspiration / gastroesophageal reflux Results of Impaired Airway Clearance Airway obstruction Mucus plugging Atelectasis Impaired gas exchange Infection Inflammation A Vicious Cycle Entering the Cycle ASTHMA NEUROMUSCULAR WEAKNESS PRIMARY CILIARY DYSKINESIA ASPIRATION GASTROESOPHAGEAL REFLUX CYSTIC FIBROSIS ASPERGILLOSIS AIRWAY CLEARANCE TECHNIQUES Airway Clearance Techniques Goals Conventional Methods Newer Therapies Therapy Adjuncts Goals Interrupt cycle of lung tissue destruction Decrease infection and illness Improve quality of life Conventional methods Cough Chest Physiotherapy Exercise Cough Natural response Only partially effective Frequent coughing leads to “floppy” airways May be suppressed by patient Chest Physiotherapy (CPT) Can be used with infants Requires caregiver participation Technique dependent Time consuming Physically demanding Requires patient tolerance Effectiveness debated Exercise Recommended for most patients Pulmonary rehabilitation expectation Training – – Ability to exercise related more to muscle mass than to pulmonary function Improves oxygen uptake by muscle cells Many patients limited by physical disability Newer Therapies PEP valve Flutter In-Exsufflator HFCWO (Vest) Intrapulmonary percussive ventilation (IPV) Cornet PercussiveTech HF PEP valve Positive Expiratory Pressure Action: splints airways during exhalation Can be used with aerosolized medications Technique dependent Portable Time required: 10 - 15 minutes Flutter Action: loosens mucus through expiratory oscillation; positive expiratory pressure splints airways Used independently Technique dependent Portable May not be effective at low airflows Time required: 10 - 15 minutes In-Exsufflator Action: creates mechanical “cough” through the use of high flows at positive and negative pressures Positive/negative pressures up to 60 cm of water Used independently or with caregiver assistance Technique independent Portable ABI Vest (HFCWO) Action: applies High Frequency Chest Wall Oscillation to entire thorax; moves mucus from peripheral to central airways Used independently or with minimal caregiver supervision May be used with aerosolized medications Technique independent Portable Time required: 15-30 minutes Intrapulmonary Percussive Ventilation (IPV) Action: “percussion” on inspiration, passive expiration; dense, small particle aerosol Used independently or with caregiver supervision Used with aerosolized meds Technique dependent May not be well tolerated by patient Time required: 20 minutes Other devices Cornet – – Similar to action of Flutter Lower cost, disposable PercussiveTech HF – – – Hand-held device used with aerosol meds Similar to action of IPV Requires 50 PSI gas source European / Canadian Techniques Huff cough (forced expiratory technique) Active Cycle of Breathing Technique (ACBT) Autogenic Drainage Forced Expiratory Technique “Huff” cough – – – – – Three second breath hold Open glottis Prevents airway collapse Effective technique for “floppy” airways Easy to learn Active Cycle of Breathing Technique Three steps: – – – Breathing control Thoracic expansion / breath hold Forced expiratory technique May be performed independently Easily tolerated Autogenic Drainage Three phases – – – Unsticking Collecting Evacuating May be performed independently Harder to teach and to learn than other techniques May be difficult for very sick patients to perform Autogenic Drainage Cough IRV UNSTICKING VT Normal Breathing ERV RV Complete Exhalation COLLECTING EVACUATING THERAPY ADJUNCTS Therapy Adjuncts Antibiotics Bronchodilators Anti-inflammatory drugs Mucolytics Nutrition Antibiotics Oral Intravenous Nebulized – Aminoglycosides: P. aeruginosa Gentamycin: 40-80 mg Tobramycin: 40-120 mg Tobi: 300 mg per dose: high dose inhibits mutation of P. aeruginosa in lung Bronchodilators Hyperreactive airways common in many pulmonary conditions Albuterol, Atrovent MDI or nebulized Administered prior to other therapies Mucolytics Mucomyst (acetylcysteine) – – Pulmozyme (dornase alfa or DNase) – – Breaks disulfide bonds Airway irritant Targets extracellular DNA in sputum Specifically developed for cystic fibrosis Hypertonic saline – – Sputum induction Australian studies Anti-inflammatory Drugs Inhaled steroids via metered dose inhaler Oral or IV prednisone High-dose ibuprofen (cystic fibrosis) Nutrition Connection between nutrition and lung function! Worsening lung function increased work of breathing & frequent coughing increased caloric need Increasing dyspnea decreased caloric intake malnutrition decreased ability to fight infection worsening lung function Interrupting the Vicious Cycle AIRWAY CLEARANCE TECHNIQUES