Spirometry is a test used to measure lung function by having a patient forcefully exhale into a spirometer. It measures volumes like forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) to diagnose and monitor conditions like COPD. The document discusses the different types of spirometers, normal values, how to interpret tests for obstructive, restrictive, and mixed lung disease patterns, and practical considerations for administering spirometry tests.

1. SPIROMETRY Dr.Tasleem Arif Dept.of Chest Medicine SKIMS MC/H Bemina By

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

3. Why Perform Spirometry? Measure airflow obstruction to help make a definitive diagnosis of COPD Confirm presence of airway obstruction Assess severity of airflow obstruction in COPD Detect airflow obstruction in smokers who may have few or no symptoms Monitor disease progression in COPD Assess fitness in divers Assess prognosis (FEV 1 ) in COPD Perform pre-operative assessment

4. 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

5. Volume Measuring Spirometer

6. Flow Measuring Spirometer

7. Desktop Electronic Spirometers

8. Small Hand-held Spirometers

9. Standard Spirometric Indicies FEV 1 - 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 FEV 1 /FVC ratio: T he fraction of air exhaled in the first second relative to the total volume exhaled

10. 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 FEV 6 – 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

11. Spirogram Patterns Normal Obstructive Restrictive Mixed Obstructive and Restrictive

12. Predicted Normal Values Age Height Sex Ethnic Origin Affected by:

13. Criteria for Normal Post-bronchodilator Spirometry FEV 1 : % predicted > 80% FVC: % predicted > 80% FEV 1 /FVC: > 0.7

14. Normal Trace Showing FEV 1 and FVC 1 2 3 4 5 6 1 2 3 4 Volume, liters Time, seconds FVC 5 1 FEV 1 = 4L FVC = 5L FEV 1 /FVC = 0.8

15. SPIROMETRY OBSTRUCTIVE DISEASE

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

17. Spirometric Diagnosis of COPD COPD is confirmed by post–bronchodilator FEV 1 /FVC < 0.7 Post-bronchodilator FEV 1 /FVC measured 15 minutes after 400µg salbutamol or equivalent

18. Bronchodilator Reversibility Testing Provides the best achievable FEV 1 (and FVC) Helps to differentiate COPD from asthma Must be interpreted with clinical history - neither asthma nor COPD are diagnosed on spirometry alone

19. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD Preparation Tests should be performed when patients are clinically stable and free from respiratory infection Patients should not have taken: inhaled short-acting bronchodilators in the previous six hours long-acting bronchodilator in the previous 12 hours sustained-release theophylline in the previous 24 hours

20. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD Spirometry FEV 1 should be measured (minimum twice, within 5%) before a bronchodilator is given The bronchodilator should be given by metered dose inhaler through a spacer device or by nebulizer to be certain it has been inhaled The bronchodilator dose should be selected to be high on the dose/response curve (…..continued)

21. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD Spirometry (continued) Possible dosage protocols: 400 µg β 2 -agonist, or 80-160 µg anticholinergic, or the two combined FEV 1 should be measured again: 10-15 minutes after a short-acting  2 -agonist 30-45 minutes after the combination

22. Figure 5.1-6. Bronchodilator Reversibility Testing in COPD Results An increase in FEV 1 that is both greater than 200 ml and 12% above the pre-bronchodilator FEV 1 (baseline value) is considered significant It is usually helpful to report the absolute change (in ml) as well as the % change from baseline to set the improvement in a clinical context

23. SPIROMETRY RESTRICTIVE DISEASE

24. Criteria: Restrictive Disease FEV 1: % predicted < 80% FVC: % predicted < 80% FEV 1 /FVC: > 0.7

25. Volume, liters Time, seconds FEV 1 = 1. 9 L FVC = 2 .0 L FEV 1 /FVC = 0. 95 1 2 3 4 5 6 5 4 3 2 1 Spirometry: Restrictive Disease Normal Restrictive

26. Mixed Obstructive/Restrictive FEV 1 : % predicted < 80% FVC: % predicted < 80% FEV 1 /FVC: < 0.7

27. Mixed Obstructive and Restrictive Volume, liters 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) FEV 1 = 0.5 L FVC = 1.5 L FEV 1 /FVC = 0. 30 Normal Obstructive - Restrictive

28. PRACTICAL SESSION Performing Spirometry

29. Withholding Medications Before performing spirometry, withhold: Short acting β 2 -agonists for 6 hours Long acting β 2 -agonists for 12 hours Ipratropium for 6 hours Tiotropium for 24 hours Optimally, subjects should avoid caffeine and cigarette smoking for 30 minutes before performing spirometry

30. Performing Spirometry Breath in until the lungs are full Hold the breath and seal the lips tightly around a clean mouthpiece Apply nose clips Blast the air out as forcibly and fast as possible . Provide lots of encouragement! Continue blowing until the lungs feel empty

31. Watch the patient during the blow to assure the lips are sealed around the mouthpiece Check to determine if an adequate trace has been achieved Repeat the procedure at least twice more until ideally 3 readings within 100 ml or 5% of each other are obtained Performing Spirometry

32. Spirometry - Possible Side Effects Feeling light-headed Headache Getting red in the face Fainting: reduced venous return or vasovagal attack (reflex) Tran s ient u rinary incontinence Spirometry should be avoided after recent heart attack or stroke

33. Spirometry – Common Problems Inadequate or incomplete blow Lack of blast effort during exhalation Slow start to maximal effort Lips not sealed around mouthpiece Coughing during the blow Extra breath during the blow Glottic closure or obstruction of mouthpiece by tongue or teeth Poor posture – leaning forwards

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