1 - Intro to PFTs

Info from 'Wilkins' Clinical Assessment in Respiratory Care,' 9th edition

tidal volume (TV, V_T)

volume of air that a person inhales and exhales during normal breathing

inspiratory reserve volume (IRV)

volume of air that a person can inhale beyond normal inspiration

expiratory reserve volume (ERV)

volume of air that a person can exhale beyond normal expiration

residual volume (RV)

volume of air that is left in the lungs after maximal expiration

inspiratory capacity (IC)

maximum amount of air that a person can inhale

(V_T + IRV)

functional residual capacity (FRC)

amount of air left in lungs after normal expiration

(ERV + RV)

vital capacity (VC)

maximum amount of air that a person can inhale and exhale

(IRV + V_T + ERV)

total lung capacity (TLC)

total amount of air that the lungs can hold

(IRV + V_T + ERV + RV)

obstructive lung disease

lung impairment that reduces/limits flow

examples:

• COPD (emphysema + bronchitis)

• bronchiectasis (excessive production of purulent secretions)

• asthma

• cystic fibrosis (CF)

• upper/large airway obstruction

restrictive lung disease

lung impairment that reduces volume

examples:

• pulmonary fibrosis/interstitial lung disease

• pleural/chest wall disease

• obesity

• mesothelioma

• neuromuscular disease

• surgery

• acute lung disease

other types of lung impairments

• coronary heart failure (CHF) / cor pulmonale

• lung transplantation

PFT categories

• spirometry (airway function)

• lung volumes & ventilation

• diffusing capacities

• blood gases & exchange tests

• cardiopulmonary exercise testing

• specialized testing

goals of PFTs

• detect:

  • airflow limitation

  • restriction

  • impaired gas transfer abnormalities

  • respiratory muscle weakness

• assess lung function over time

spirometry indications

• diagnose presence/absence of disease

• quantify extent of known disease

• measure effects of environment exposure

• determine effects of therapy

• assess risk for surgery

• evaluate disability/impairment

• research

total lung volume/capacity study indications

• diagnose/assess restrictive/obstructive lung disease

• differ between restrictive or obstructive disease

• assess response to therapy

• preoperative assessment of patient with respiratory compromise

• determine extent of hyperinflation

• standardize lung function measurement

diffusing capacity (DLCO) indications

• evaluate progress of parenchymal disease

• evaluate respiratory compromise in systemic disease

• evaluate COPD

• evaluate CV disease

• quantify disability for interstitial lung disease

• evaluate pulmonary hemorrhage, polycythemia, L-to-R shunt

arterial blood gas (ABG) indications

• evaluate adequacy of lung function

• determine need for supplemental oxygen

• monitor mechanical ventilatory support

• document severity/progression of known lung disease

• provide supporting other PFT measurements

exercise testing indications

• evaluate exercise tolerance

• document/diagnosis exercise limitations

• evaluate for pulmonary rehab

• assess pre-op risk

• assess disability

• evaluate therapeutic interventions

specialized PFTs

• bronchoprovocation

• hyper-reactivity

• metabolic measurements

• disability determination

patient preparation for PFTs

• stop certain medications (inhalers, nebulizers, etc.)

• smoking cessation (1-4 hours before test)

• no large meals or exercise before test

• consider accommodations if applicable

measurements done before PFTs

• age

• height (if patient can’t stand, use wingspan)

• gender

• race/ethnicity

• weight

physical assessment before PFTs

• lung sounds

• HR

• SpO₂

history information prior to PFTs

• reason for test

• family history

• personal history

• occupational/environmental exposure

• smoking habits

• cough

• dyspnea

• current medications

PFT performance and sequence

• policies/procedure (ie, American Thoracic Society [ATC])

• protocols

  • established

  • adapted

  • timing

• patient instruction

  • valid data

  • COACHING (watch for inability)