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  • Respiratory Therapy

  • Pulmonary Function Tests (PFTs)

  • Differential Diagnosis of PFTs

  • Oxygen Supplementation

  • Pulse Oximetry

  • Postoperative Pulmonary Care

  • Bronchopulmonary Hygiene

  • Aerosol (Nebulizer) Therapy

  • Topical Medications

  • Inhalers

  • Chest Physiotherapy

    • Incentive Spirometry

    • Flutter Devices (Acapella©, Aerobika©, Cornet©)

    • High-Frequency Chest Wall Oscillation Device


Respiratory therapy is a vital component of healthcare. For any patient, initial medical care begins with assessment of the ABCs: Airway, Breathing, and Circulation. Respiratory therapy includes key components of airway and breathing management and support. The objective is the care of all types of patients with cardiopulmonary diseases. Functions of the respiratory therapist include emergency care, airway management, ventilatory support, oxygen therapy, aerosol therapies, chest physiotherapy (CPT), physiologic monitoring, and pulmonary diagnostics. Special precautions relating to disease transmission due to aerosol generating respiratory procedures are reviewed in Chapter 19 on Universal and Standard Precautions.


Pulmonary function tests (PFTs) are essential in the diagnosis of a variety of pulmonary disorders. Common PFTs include spirometry, lung volume determinations, and diffusing capacity. Other components include maximal voluntary ventilation (MVV), maximal inspiratory effort (MIP), and maximal expiratory effort (MEP). Important spirometric measurements include forced vital capacity (FVC), forced expired volume in 1 s (FEV1), and FEV1/FVC. Spirometry results indicate the presence of obstructive airway diseases such as asthma or chronic obstructive pulmonary disease (COPD) when the FEV1/FVC ratio is <0.70 or <LLN (lower limit of normal). A fixed ratio of <0.70 should be used in adults 65 years or older who are at risk for COPD. The LLN should be used for younger patients or never smokers. Both methods can lead to over- and underdiagnosis. If the FVC is <LLN and the FEV1/FVC ratio is normal, this suggests restrictive lung diseases such as interstitial lung disease or neuromuscular disease. Restrictive lung disease must be confirmed by lung volume testing.

Obtain spirometry before and after administration of bronchodilators unless contraindicated to evaluate for reversible obstruction. A bronchodilator response is considered significant if the FEV1 or the FVC improves by 12% and at least 200 mL.

Order lung volumes, determined by helium dilution or body plethysmography, to definitively diagnose restrictive lung disease. Restriction is present when TLC <80% of predicted normal. Hyperinflation is present if TLC >120%, and air trapping is present if residual volume (RV)/TLC is >50%. A reduction in diffusing capacity is used in the diagnosis of interstitial lung disease and pulmonary vascular disease. Spirometry and diffusing capacity should be measured in all patients being considered for lung resection surgery.

Normal PFT values vary with age, sex, race, and body size. Normal values for a given patient are established from studies of healthy populations and are provided along with the results. The most commonly used ...

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