SPIROMETRY IN PRIMARY CARE IMAD SHAWA, MD, FCCP DIRECTOR OF CRITICAL CARE CHAIRMAN OF MEDICINE FRANCISACN HEALTH-INDIANAPOLIS

I have no relevant financial relationships to disclose. disclosures

Respiratory pump Cardiac pump Air-Blood interface Basic physiology

Respiratory system Two balloons connected to air ducts Air is pumped into contact with the blood (Alveolar Capillary interface) Air is pumped back out Respiratory system

THE LUNGS

Respiratory system Balloon Size & amount of air: Air ducts: Spirometry Lung Volumes Air ducts: Airway resistance Air/Blood interface: Diffusion Pump strength neuromuscular test Respiratory system

Spirometry

What is Spirometry? Spirometry is a method of assessing lung function by measuring the total volume of air the patient can expel from the lungs after a maximal inhalation.

Flow Measuring Spirometer

Lung Volume Terminology

Lung Volume Terminology Inspiratory reserve volume Inspiratory capacity Total lung capacity Tidal volume Expiratory reserve volume Vital capacity Residual volume

Standard Spirometric Indicies FEV1 - Forced expiratory volume in one second: The volume of air expired in the first second of the blow FVC - Forced vital capacity: The total volume of air that can be forcibly exhaled in one breath FEV1/FVC ratio: The fraction of air exhaled in the first second relative to the total volume exhaled

Additional Spirometric Indicies VC - Vital capacity: A volume of a full breath exhaled in the patient’s own time and not forced. Often slightly greater than the FVC, particularly in COPD FEV6 – Forced expired volume in six seconds: Often approximates the FVC. Easier to perform in older and COPD patients but role in COPD diagnosis remains under investigation MEFR – Mid-expiratory flow rates: Derived from the mid portion of the flow volume curve but is not useful for COPD diagnosis

Indications Evaluation of Dyspnea Evaluation of cough Recognition of COPD in asymptomatic smokers Diagnosis of Obstructive and restrictive lung Dz Evaluation of response to Rx Surveillance for drug induced lung toxicity Pre-Op evaluation Neuro-Muscular weakness Disability evaluation Indications

Types of Spirometers Bellows spirometers: Measure volume; mainly in lung function units Electronic desk top spirometers: Measure flow and volume with real time display Small hand-held spirometers: Inexpensive and quick to use but no print out

Volume Measuring Spirometer

Desktop Electronic Spirometers

Small Hand-held Spirometers

Spirometry Predicted Normal Values

Predicted Normal Values Affected by: Age Height Sex Ethnic Origin

Criteria for Normal Post-bronchodilator Spirometry FEV1: % predicted > 80% FVC: % predicted > 80% FEV1/FVC: > 0.7 - 0.8, depending on age

Mixed Obstructive and Restrictive Spirogram Patterns Normal Obstructive Restrictive Mixed Obstructive and Restrictive

Normal Trace Showing FEV1 and FVC 5 4 FEV1 = 4L FVC = 5L FEV1/FVC = 0.8 Volume, liters 3 2 1 1 1 2 3 4 5 6 Time, sec

SPIROMETRY OBSTRUCTIVE DISEASE

Spirometry: Obstructive Disease Normal 5 4 3 Volume, liters FEV1 = 1.8L FVC = 3.2L FEV1/FVC = 0.56 2 Obstructive 1 1 2 3 4 5 6 Time, seconds

Bronchodilator Reversibility Testing Provides the best achievable FEV1 (and FVC) Helps to differentiate COPD from asthma Must be interpreted with clinical history - neither asthma nor COPD are diagnosed on spirometry alone

SPIROMETRY RESTRICTIVE DISEASE

Criteria: Restrictive Disease FEV1: normal or mildly reduced FVC: < 80% predicted FEV1/FVC: > 0.7

Spirometry: Restrictive Disease Normal 5 4 3 Volume, liters Restrictive FEV1 = 1.9L FVC = 2.0L FEV1/FVC = 0.95 2 1 1 2 3 4 5 6 Time, seconds

Mixed Obstructive/Restrictive FEV1: < 80% predicted FVC: < 80% predicted FEV1 /FVC: < 0.7

Mixed Obstructive and Restrictive Normal Volume, liters FEV1 = 0.5L FVC = 1.5L FEV1/FVC = 0.30 Obstructive - Restrictive Time, seconds Restrictive and mixed obstructive-restrictive are difficult to diagnose by spirometry alone; full respiratory function tests are usually required (e.g., body plethysmography, etc)

SPIROMETRY Flow Volume

Flow Volume Curve Standard on most desk-top spirometers Adds more information than volume time curve Less understood but not too difficult to interpret Better at demonstrating mild airflow obstruction

Flow Volume Curve Maximum expiratory flow (PEF) FVC Volume (L) Expiratory flow rate L/sec FVC RV TLC Inspiratory flow rate L/sec Volume (L)

Flow Volume Curve Patterns Obstructive and Restrictive Severe obstructive Restrictive Expiratory flow rate Expiratory flow rate Expiratory flow rate Volume (L) Volume (L) Volume (L) Reduced peak flow, scooped out mid-curve Steeple pattern, reduced peak flow, rapid fall off Normal shape, normal peak flow, reduced volume

Spirometry: Abnormal Patterns Obstructive Restrictive Mixed Volume Volume Volume Time Time Time Slow rise, reduced volume expired; prolonged time to full expiration Fast rise to plateau at reduced maximum volume Slow rise to reduced maximum volume; measure static lung volumes and full PFT’s to confirm

Spirometry - Possible Side Effects Feeling light-headed Headache Getting red in the face Fainting: reduced venous return or vasovagal attack (reflex) Transient urinary incontinence Spirometry should be avoided after recent heart attack or stroke

Unacceptable Trace - Poor Effort Normal Volume, liters Variable expiratory effort Inadequate sustaining of effort May be accompanied by a slow start Time, seconds

Unacceptable Trace – Stop Early Normal Volume, liters Time, seconds

Unacceptable Trace – Slow Start Normal Volume, liters Time, seconds

Unacceptable Trace - Coughing Normal Volume, liters Time, seconds

Unacceptable Trace – Extra Breath Normal Volume, liters Time, seconds

Some Spirometry Resources Global Initiative for Chronic Obstructive Lung Disease (GOLD) - www.goldcopd.org Spirometry in Practice - www.brit-thoracic.org.uk ATS-ERS Taskforce: Standardization of Spirometry. ERJ 2005;29:319-338 www.thoracic.org/sections/publications/statements National Asthma Council: Spirometry Handbook www.nationalasthma.org.au

Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2010