1 Pulmonary Function Tests J.B. Handler, M.D. Physician Assistant Program University of New England

2 Abbreviations ARDS- adult respiratory distress syndrome ARDS- adult respiratory distress syndrome DL CO - diffusion capacity for carbon monoxide DL CO - diffusion capacity for carbon monoxide Ht- height Ht- height Wt- weight Wt- weight SOB- short of breath SOB- short of breath Pred- predicted Pred- predicted Meas- measured Meas- measured PFT- pulmonary function test PFT- pulmonary function test ABG- arterial blood gas ABG- arterial blood gas

3 PFT’s: Indications Detect abnormalities and severity of lung function in presence of disease. Detect abnormalities and severity of lung function in presence of disease. –Monitor course of disease. Baseline pulmonary function prior to surgical, medical or radiation therapy. Baseline pulmonary function prior to surgical, medical or radiation therapy. Differentiation of obstructive vs restrictive disease. Differentiation of obstructive vs restrictive disease. Evaluate response to therapy, reversibility. Evaluate response to therapy, reversibility. Determine the preoperative risk of thoracic surgery. Determine the preoperative risk of thoracic surgery.

Lung Volumes Images.google.com

Lung Volumes Tidal Volume (TV): amount of air inhaled and exhaled at rest; normal= ml. Tidal Volume (TV): amount of air inhaled and exhaled at rest; normal= ml. Inspiratory Capacity (IC): beginning of normal inhalation to maximum inspiration Inspiratory Capacity (IC): beginning of normal inhalation to maximum inspiration. Images.google.com IC

Lung Volumes Inpiratory Reserve Volume (IRV): Volume measured from “top” of the TV (point of normal exhalation) to maximum inspiration. Inpiratory Reserve Volume (IRV): Volume measured from “top” of the TV (point of normal exhalation) to maximum inspiration. Expiratory Reserve Volume (ERV): Volume measured from the “bottom” of the TV (point of normal inhalation) to maximum expiration. Expiratory Reserve Volume (ERV): Volume measured from the “bottom” of the TV (point of normal inhalation) to maximum expiration. Images.google.com

Lung Volumes Residual Volume (RV): The amount of air left in the lungs following full exhalation to the ERV.. Residual Volume (RV): The amount of air left in the lungs following full exhalation to the ERV.. Functional Residual Capacity (FRC) = ERV + RV: amount of gas remaining in the lungs at the end of the tidal volume. Functional Residual Capacity (FRC) = ERV + RV: amount of gas remaining in the lungs at the end of the tidal volume. Images.google.com

Lung Volumes Vital Capacity (VC): volume of air measured from full inhalation to maximum exhalation Vital Capacity (VC): volume of air measured from full inhalation to maximum exhalation Total Lung Capacity (TLC): summation of the RV + vital capacity. Total Lung Capacity (TLC): summation of the RV + vital capacity. Images.google.com

Spirometer

10 Spirometry Forced Vital Capacity (FVC)- Following full inspiration, patient exhales as rapidly as possible, forcibly and completely- volume of air exhaled is measured; takes 5-6 seconds with majority in 1 second. Wide range of normal (see below). Forced Vital Capacity (FVC)- Following full inspiration, patient exhales as rapidly as possible, forcibly and completely- volume of air exhaled is measured; takes 5-6 seconds with majority in 1 second. Wide range of normal (see below). Volume obtained is expressed as a % of predicted normal. Normals are based on volumes obtained from thousands of healthy individuals of similar age, sex, ht and wt and race. Normal  80% of predicted. Volume obtained is expressed as a % of predicted normal. Normals are based on volumes obtained from thousands of healthy individuals of similar age, sex, ht and wt and race. Normal  80% of predicted.

11 Spirometry FEV 1 :Amount of air forcibly exhaled in the 1st second of the FVC maneuver (  80% of FVC volume). Normal  80% predicted; wide range of normal (see below). FEV 1 :Amount of air forcibly exhaled in the 1st second of the FVC maneuver (  80% of FVC volume). Normal  80% predicted; wide range of normal (see below). Volume obtained is expressed as a % of predicted normal. Normals are based on volumes obtained from thousands of healthy individuals of similar age, sex, ht and wt and race. Normal  80% of predicted. Volume obtained is expressed as a % of predicted normal. Normals are based on volumes obtained from thousands of healthy individuals of similar age, sex, ht and wt and race. Normal  80% of predicted.

12 Spirometry FEV 1 /FVC: Very important ratio; when reduced, helps identify presence of obstructive disease. Percentage reduction correlates with severity of obstruction; normal is %. Normal (or  ) in patients with restrictive disease. FEV 1 /FVC: Very important ratio; when reduced, helps identify presence of obstructive disease. Percentage reduction correlates with severity of obstruction; normal is %. Normal (or  ) in patients with restrictive disease. Obstructive airway disease: Asthma, COPD. Obstructive airway disease: Asthma, COPD. Restrictive disease: Interstitial lung disease, kyphoscoliosis, pleural disease & others). Restrictive disease: Interstitial lung disease, kyphoscoliosis, pleural disease & others).

13 Peak Expiratory Flow Rate Measured using simple hand held device. Measured using simple hand held device. Occurs within the first milliseconds of forced expiration and is a measure of maximum airflow rate. Occurs within the first milliseconds of forced expiration and is a measure of maximum airflow rate. Wide variation in normal ranges (age, ht and sex) adult males: L/minute. adult females: L/minute. Wide variation in normal ranges (age, ht and sex) adult males: L/minute. adult females: L/minute. Effort dependent. Effort dependent. When abnormal- indicator of large airways obstruction. When abnormal- indicator of large airways obstruction.

14 Peak Expiratory Flow Rate Clinical use: Assessment of patients with asthma. Clinical use: Assessment of patients with asthma. Patient determines “personal best” PEFR when most healthy, between asthma attacks. Patient determines “personal best” PEFR when most healthy, between asthma attacks.  PEFR often precedes symptoms.  PEFR often precedes symptoms. Guide for responsiveness to meds, worsening of episodes, when to get help, etc. Guide for responsiveness to meds, worsening of episodes, when to get help, etc.

15 Diffusion Capacity Tests gas exchange across the alveolar-capillary membrane. Tests gas exchange across the alveolar-capillary membrane. Per minute transfer of gas- Carbon Monoxide measured from alveoli to blood; DL CO. Per minute transfer of gas- Carbon Monoxide measured from alveoli to blood; DL CO. Decreased if thickened alveolar capillary membrane (pulmonary fibrosis, ARDS), or following loss of surface area of the alveoli. Decreased if thickened alveolar capillary membrane (pulmonary fibrosis, ARDS), or following loss of surface area of the alveoli. Most useful and decreased in interstitial lung disease (lecture to follow). Most useful and decreased in interstitial lung disease (lecture to follow). Normal mean is mL/min/mmHg. Normal mean is mL/min/mmHg.

16 Application of PFT’s Obstructive disease: asthma, COPD, bronchiectasis. Obstructive disease: asthma, COPD, bronchiectasis. Pattern: FVC normal or decreased mildly. FEV 1 decreased; reduction reflects severity. Pattern: FVC normal or decreased mildly. FEV 1 decreased; reduction reflects severity. FEV 1 /FVC decreased- reflects severity. FEV 1 /FVC decreased- reflects severity. Response to bronchodilator indicates reversible component. Response to bronchodilator indicates reversible component.

17 Application of PFT’s Restrictive disease: pulmonary fibrosis, sarcoidosis, kyphoscoliosis, neuromuscular disease, others. Restrictive disease: pulmonary fibrosis, sarcoidosis, kyphoscoliosis, neuromuscular disease, others. Pattern: FVC decreased, often markedly. FEV 1 decreased, often markedly. Pattern: FVC decreased, often markedly. FEV 1 decreased, often markedly. FEV 1 /FVC normal or increased. FEV 1 /FVC normal or increased. No response to bronchodilator. No response to bronchodilator.

18 Problem Solving 22 y.o male with cough, SOB, and wheezing. FVC – 3.63L (pred), 3.23L (meas), 89% pred FVC – 3.63L (pred), 3.23L (meas), 89% pred FEV L (pred), 2.24L (meas), 69% pred FEV L (pred), 2.24L (meas), 69% pred FEV 1 /FVC 69% (meas) Post bronchodilator: FEV 1 /FVC 69% (meas) Post bronchodilator: FVC- 3.23L FVC- 3.23L FEV L (meas) 83% pred FEV L (meas) 83% pred FEV 1 /FVC 84% (meas) FEV 1 /FVC 84% (meas) Interpretation: mild obstructive airways disease with post bronchodilator reversibility. Interpretation: mild obstructive airways disease with post bronchodilator reversibility. Diagnosis: Asthma Diagnosis: Asthma

19 Problem Solving 45 y.o black man with progressive shortness of breath. 45 y.o black man with progressive shortness of breath. FVC- 3.05L (pred), 0.81L (meas), 22% predicted FVC- 3.05L (pred), 0.81L (meas), 22% predicted FEV L (pred) 0.69L (meas), 24% predicted FEV L (pred) 0.69L (meas), 24% predicted FEV 1 /FVC 97% (meas) FEV 1 /FVC 97% (meas) No change post bronchodilator No change post bronchodilator Interpretation: Severe restrictive disease; no evidence of airway obstruction. Interpretation: Severe restrictive disease; no evidence of airway obstruction. Diagnosis: Sarcoidosis Diagnosis: Sarcoidosis

20 Pulse Oximetry Measures per cent oxygenation of hemoglobin (oxyhemoglobin). Measures per cent oxygenation of hemoglobin (oxyhemoglobin). Non-invasive; measures absorption of light passing through tissue, then calculates O 2 saturation of arterial blood. Non-invasive; measures absorption of light passing through tissue, then calculates O 2 saturation of arterial blood. Measured via electrodes placed on skin- fingertips, ear lobes. Measured via electrodes placed on skin- fingertips, ear lobes. Normal = 97% Normal = 97%

21 Arterial Blood Gas Measurement Requires arterial puncture Requires arterial puncture pH of arterial blood pH of arterial blood PO 2 : partial pressure of oxygen (mmHg) PO 2 : partial pressure of oxygen (mmHg) PCO 2 : partial pressure of carbon dioxide (mmHg) PCO 2 : partial pressure of carbon dioxide (mmHg) HCO 3 : calculated- bicarbonate; proportional to dissolved CO 2 in blood. HCO 3 : calculated- bicarbonate; proportional to dissolved CO 2 in blood.

O 2 -Hemoglobin Dissociation Images.google.com