Interpreting Spirometry Vikki Knowles BSc(Hons) RGN Respiratory Nurse Consultant G & W`CCG
Why Spirometry? supports diagnosis classifies defect - obstructive/restrictive assesses -severity of defect - response to treatment - suitability for anaesthesia monitors progress
Lung Volumes
What is spirometry? measures volume of air expelled from lungs after maximal inspiration Without regard to time -relaxed vital capacity VC As a forced manoeuvre -forced vital capacity FVC -forced expiratory volume in 1 second FEV 1
Pre Test Considerations
Contraindications? Haemoptysis of unknown origin Pneumothorax Unstable cardiovascular status Thoracic, abdominal or cerebral aneurysms Recent eye surgery Recent thoracic or abdominal surgery
Before you start Check..
A reliable result 3 x forced manoeuvres Best 2 within 5% and 100 ml of each other The curve should be smooth and free of irregularities The curve should reach a plateau
Rejecting results Second breath Early termination of effort Inadequate inspiration Poor seal around mouthpiece Slow start to expiration Coughing, vocalising, puffing cheeks Leakage, nose, tube, bellows Early termination of the blow (<3secs) Submaximal effort Obstructing mouthpiece by tongue or false teeth
Normal values FEV1 > 80% predicted (Measured FEV1/Predicted X 100) FVC > 80% Predicted (Measured FVC/Predicted x 100) FEV1/FVC ratio > 70% or LLN (Measured FEV1/Measured FVC x100)
Predicted Values Europe Cogswell, Solymar, Zapletal (1975) 6-17 years, ECCS (1993) 18-120 years.
Normal Spirometric curve FEV1%FVC = (4.05 x 100)/4.85= 83.5%
Peter Age 30 Symptoms Nocturnal breathlessness Wheeze SOBOE Hypersomnolence
Peter (2) PMH Possible asthma Morbid Obesity Family history Mother and brother asthma Drug Treatment Salbutamol prn Social History Non smoker Taxi driver
Peter (3) PEFR 520 FEV1 2.74 (77%) FVC 3.44 (80%) FEV1% 79% SpO2 98% CXR Lung fields clear
Normal FEV1 and VC with SOB,? Dyspnoea in this group should be investigated fully Most Patients - Exercise Induced Asthma Alveolitis Diffuse Pulmonary Fibrosis Heart Disease Pulmonary Thromboembolism Neurological/Metabolic causes
Obstructive Disorder Lumen of airway affected by Inflammation Bronchoconstriction Excessive mucous production Asthma COPD Bronchiectasis
Obstructive Picture
Ann History 54 yr old female Breathless for several years Ex smoker of 2 months 40 pack years No FH atopy Farmer s wife Breathless at night
Ann Symptoms and medication SOBOE Productive cough 3 courses antibiotics and prednisolone last 12 months MRC Dypnoea 3 Bilateral mild ankle oedema On Salbutamol and Beclometasone
Ann Investigation results On chest auscultation: wheeze, no crackles CXR NAD, heart size normal O 2 saturations 93% on air at rest PFTs Echocardiogram: NAD FBC: Normal
Reversibility Testing
Treatment Add LABA/LAMA combination Continue salbutamol prn Discontinue beclometasone consider combination LABA/ICS if continued exacerbations Pulmonary Rehabilitation Self Management Plan
Result Feels well Able to help with work on the farm more fully again
Severity COPD
Restrictive Disorder Ability of the lungs to expand affected by Inflammation/fibrosis/scarring Rib cage deformity Muscular or neuromuscular weakness Fibrosis Pneumoconiosis Kyphoscoliosis Ankylosing spondylitis Polio Surgery
Restrictive picture
Brian Symptoms Shortness of breath for 2 months Dry Cough
Brian PMH Nil of note Childhood illnesses Drug Tx None FH Father Ca Lung Social Hx Ex smoker (12 pack years) Retired garage mechanic
Brian O/E: Fine end inspiratory crackles CXR: Patchy shadowing mid and lower zones
Combined defect Features of obstructive and restrictive defect Cystic fibrosis Severe COPD
Combined picture
Combined picture
Calculations % of predicted Measured x 100 Predicted FEV 1 /FVC ratio FEV 1 x 100 FVC % Difference Difference x 100 Highest value Eg 1.2 x 100 =33% 3.6 Eg 2.7 x 100 =75% 3.6 Eg PF220 increases 310 110 x 100 =35% 310
Interpretation