Presentation on theme: "Interpreting Spirometry: Patient or Data? David Robiony-Rogers CRFS Service Leader Respiratory Medicine Capital & Coast District Health Board."— Presentation transcript:
Interpreting Spirometry: Patient or Data? David Robiony-Rogers CRFS Service Leader Respiratory Medicine Capital & Coast District Health Board
The colours of disease
The colours of respiratory disease
For the movie conscious...
For the spacer conscious...
Medication type colour coding...
Spirometry Spirometry is the timed measurement of dynamic lung volumes during forced expiration and inspiration, and is used to quantify how effectively and how quickly the lungs can be emptied.
Spirometry: Graphic Displays Volume time curveFlow volume loop
Spirometry Interpretation Acceptability *minimum of 3 acceptable manoeuvres *good start and satisfactory effort *no artefacts induced by coughing or glottic closure in 1st second, or equipment problems *minimum of 6 seconds exhalation and/or plateau in the volume time curve *Maximal inspiration prior to blow
Artefacts a)No artefact b)Cough within 1 st second of forced exhalation c)Incomplete exhalation/early termination (glottic closure) d)Slow start/submaximal forced effort at start of blow e)Hesitant start
Spirograms Normal and problematic
Flow Volume Loops Normal and problematic
Reproducibility *two largest FVC within 0.150 L (150ml) of each other *two largest FEV1 within 0.150 L (150ml) of each other *must meet criteria for acceptability If the reproducibility criteria is not met after a total of 8 tests, stop testing.
Disease Patterns Obstructive pattern A disproportionate reduction of maximal airflow from the lung in relation to the maximal volume Restrictive pattern Characterised by a normal FEV 1 /VC ratio and reduction in FVC below the 5th percentile of the predicted Mixed pattern Characterised by the coexistence of obstruction and restriction, and is defined physiologically when both FEV 1 /FVC and FVC are below 5th percentiles of the predicted value
Spirometric overlap between Asthma and COPD *COPD has been described as a disease characterized by fixed airflow obstruction because in many patients FEV1 values improve little after bronchodilator challenge. *Current guidelines on diagnosis and management describe COPD as a condition that is partially reversible because some patients exhibit substantial improvements in FEV1 (despite an FEV1-FVC ratio that remains below 0.70) that compares in magnitude to what is observed in some asthma patients. *Tashkin et al (2008) have shown that about 54% of a large COPD cohort (N = 5756) exhibited an improvement in FEV1 values > 12% and 200 mL, while about 65% of patients had FEV1 increases > 15%. *This substantial overlap in FEV1 reversibility between asthma and COPD underscores an important limitation of using this measurement to distinguish between asthma and COPD. Can Fam Physician. Oct 2011; 57(10): 1148–1152.
The overlap of Asthma and COPD
Disease Patterns The presence and site of disease have various effects on the volume- time and maximal expiratory flow volume curve Vitalograph Ltd 1986 &2000
Normal Ventilatory Function The pattern of the lung and spirogram show a pattern of normality Vitalograph Ltd 1986 &2000
Age: 22, Gender: Female; Height: 166 cm, Weight: 69.3 kg; BMI: 25.15 Spirometry measureBestReferenceRef ± CI FVC, L 3.633.953.2 – 4.7 FEV1, L 3.023.432.8 – 4.0 FEV1/FVC, % 8376.3 – 95.9
Reversible Obstruction The lungs and spirogram show a pattern of airway obstruction (black), with the spirogram showing a marked improvement after the administration of a bronchodilator (red) Vitalograph Ltd 1986 &2000
Age: 29; Gender: Female; Height: 162 cm; Weight: 98.6 kg; BMI: 37.57 Spirometry measurePre bronchodilator best Post bronchodilator best % improvementReferenceRef ± CI FVC, L 2.223.51 58 3.75 3.1 – 4.4 FEV1, L 1.49 2.68 80 3.18 2.6 – 3.8 FEV1/FVC, % 67 76 74.9 – 94.4
Irreversible Obstruction The lungs and spirogram show a pattern of airflow obstruction, with the spirogram showing little or no improvement after the administration of a bronchodilator Vitalograph Ltd 1986 &2000
Response to ß2-agonist ß2-agonist bronchodilator *Dose: 4 puffs of ß2-agonist delivered through a spacer device *Wait 15-20 minutes before repeating spirometry *Significant response defined as >12% and more than 200mL increase in either the FEV1 or FVC.
Spirometry: Pre & Post ß2-agonist
Severity classification Degree of severityFEV1 % predicted Mild>70 Moderate60-69 Moderately severe50-59 Severe35-49 Very severe<35 Severity of any spirometric abnormality based on the forced expiratory volume in one second (FEV1) ATS/ERS Task Force: Standardisation of lung function testing. Interpretative strategies for lung function tests. Eur Respir J 2005; 26: 948
Interpretation algorithm National Asthma Council Australia: www.nationalasthma.org.au Yes No
Spirometry interpretation algorithm: Primary Care Respiratory Alliance of Canada Asthma vs COPD (history)Consistent with asthma Refer to specialist FEV1, 12% and 200mL Restrictive disorder Reduced < LLNNormal (not COPD) FVC ≥ 80% predicted FEV1 and FVC ß2-agonist Reduced < LLNNormal > LLN Pre ß2-agonist FEV1/FVC ratio Modified from Primary Health Care Alliance of Canada spirometry interpretation algorithm 2011
https://www.youtube.com/watch?v=yNDKD_xI684 Spirometry Education Pulmonary Function Tests (PFT): Lesson 2 - Spirometry Published on Feb 3, 2014 A discussion of FEV1, FVC, FEV1/FVC ratio, and the flow volume loop, including how these are used in the diagnosis of various lung diseases, with a particular focus on the distinction between obstructive and restrictive lung disease. A summary of flow volume loop patterns in upper airway obstruction is covered as well.