SPE3ESP - Pulmonary Function Lecture PDF

latrobe.edu.au SPE3ESP Understanding pulmonary function La Trobe University CRICOS Provider Code Number 00115M 1...

latrobe.edu.au SPE3ESP Understanding pulmonary function La Trobe University CRICOS Provider Code Number 00115M 1 latrobe.edu.au Lecture outcomes By the end of this lecture, you should be able to:  Discuss the mechanics of ventilation  Analyse and interpret static lung volume and capacity measurements, and dynamic lung volume measurements  Critically evaluate the factors affecting lung volume  Analyse the effect of obstructive and restrictive pulmonary diseases on lung volume  Describe the aetiology, pathophysiology, symptoms and management of asthma, exercise-induced bronchoconstriction, and chronic obstructive pulmonary disease (COPD)  Critically analyse the role and factors affecting exercise for common pulmonary diseases  Justify the recommendations for exercise testing and prescription for asthma and COPD  Discuss the considerations for exercise for asthma and COPD 2 1  latrobe.edu.au Respiratory system  Organs responsible for consuming oxygen and eliminating carbon dioxide.  Works with the circulatory system to deliver oxygen and remove waste. 3 latrobe.edu.au Mechanics of ventilation Ventilation (breathing): the movement of air flow between the atmosphere and the lungs. Boyle’s law: the volume of gas is inversely proportional to pressure (when temperature is constant).  Inspiration (active) – Inspiratory muscles contract – ↑ volume, ↓ pressure of thoracic cavity – Air moves into the lungs  Expiration (passive): – Inspiratory muscles relax – ↓ volume, ↑ pressure of thoracic cavity – Air moves out of the lungs 4 2  latrobe.edu.au Forced ventilation Active breathing that utilises additional muscles to rapidly expand and contract the thoracic cavity volume.  Active inspiration: contraction of accessory muscles to increase the volume of the thoracic cavity  Active expiration: contraction of accessory muscles to decrease the volume of the thoracic cavity 5 Lung volumes and capacities Static:  VT/TV, IRV, ERV, RV  TLC, VC, IC, FRC Dynamic:  FEV1/FVC  MVV 6 3  IRV Static lung VT/TV ERV volumes RV Lung Volume Definition Males (mL) Females (mL) Tidal Volume (VT/TV) Volume inspired or expired per breath 600 500 Inspiratory Reserve Volume (IRV) Maximum inspiration at the end of tidal inspiration 3000 1900 Expiratory Reserve Volume (ERV) Maximum expiration at the end of tidal expiration 1200 800 Residual Lung Volume (RLV) Volume in lung after maximum expiration 1200 1000 7 Static lung capacities IC = IRV + VT FRC = ERV + RV VC = IC + ERV TLC = VC + RV Lung Capacity Definition Males (mL) Females (mL) Total Lung Capacity (TLC) Volume in lungs after maximum inspiration 6000 4200 Vital Capacity (VC) Maximum volume expired after maximum inspiration 4800 3200 Inspiratory Capacity (IC) Maximum volume inspired following tidal expiration 3600 2400 Functional Residual Capacity (FRC) Volume in lungs after tidal expiration 2400 1800 8 4  latrobe.edu.au Dynamic lung volumes Lung volumes that depend on airflow levels in addition to air movement in a single breath:  Forced Vital Capacity (FVC)  Forced Expiratory Volume in 1s (FEV1)  Maximum Voluntary Ventilation (MVV) 9 latrobe.edu.au FEV1/FVC Ratio  Forced Vital Capacity (FVC): the volume of air (L) that can be forcefully and maximally exhaled after a maximal inspiration.  Forced Expiratory Volume in 1s (FEV1): the volume of air (L) that can be forcefully and maximally exhaled in the first second after maximal inspiration  FEV1/FVC: the ratio of FEV1 to FVC (%) – Healthy adults: > 70% – Healthy children: > 85% 10 5  latrobe.edu.au Peak Expiratory Flow  Peak Expiratory Flow (PEF)/Peak Expiratory Flow Rate (PEFR): Maximal flow rate achieved during maximally forced expiration initiated at full inspiration (L/min). 11 latrobe.edu.au Maximum Voluntary Ventilation (MVV)  The volume of air expired in a specified period during repetitive maximal effort – Breathe as fast and deeply as possible for 12 s – Extrapolate values to 1 min  Reference values: – Females: 80 – 120 L/min – Males: 140 – 180 L/min 12 6  latrobe.edu.au Factors affecting lung volumes and capacities  Age  Gender  Anthropometric measurements  Ethnicity  Other considerations: – Exercise – Altitude – Positioning and posture during testing 13 latrobe.edu.au SPE3ESP Pulmonary disease and exercise La Trobe University CRICOS Provider Code Number 00115M 14 7  latrobe.edu.au Understanding pulmonary disease Obstructive Pulmonary Diseases  Characterised by an increase in airway resistance – e.g. chronic bronchitis, emphysema, cystic fibrosis Restrictive Pulmonary Diseases  Characterised by a decrease in the lung’s ability to expand – e.g. deformities of the chest wall, pulmonary fibrosis, scoliosis Mixed Pulmonary Diseases  A combination of obstructive and restrictive pulmonary diseases 15 latrobe.edu.au Changes in dynamic lung volumes Obstructive ventilatory defect  FEV1/FVC only: – Adult: FEV1/FVC < 70% Parameter Obstructive Restrictive Mixed – Under 18: FEV1/FVC < 85% FEV1 ↓ ↓ or normal ↓ Restrictive ventilatory defect FVC ↓ or normal ↓ ↓  Spirometry + further evaluation of static lung volumes FEV1/FVC ↓ ↑ or normal ↓ Mixed ventilatory defect  Spirometry + further evaluation of static lung volumes Johnson & Theurer, 2014 16 8  latrobe.edu.au Asthma  Chronic inflammatory disease of the airways – Respiratory symptoms e.g. wheeze, shortness of breath, chest tightness, cough – Variable expiratory airflow limitation (↓ FEV1/FVC) – Heterogenous!  Prevalence – Highest in developed countries – Children: higher in boys than girls; Adults: higher in women than men  Types: e.g. child-onset allergic asthma, non-allergic asthma, late-onset asthma, occupational asthma 17 latrobe.edu.au Management Self-management:  Pharmacological: – Controllers: reduce inflammatory mechanisms – Relievers: relieve bronchoconstriction – Preventers: inhaled pre-exercise  Asthma Management/Action Plan  Education 18 9  latrobe.edu.au The role of exercise  Current guidelines recommend exercise as supplementary to medication  Effect on asthma: – (supervised) aerobic exercise reduced shortness of breath, improved asthma control, symptom-free days  Effect on lung function Mendes et al., 2010 – Generally no change or small improvement – Swimming?  Altitude training – Improved asthma control, reduced airway inflammation  Improves exercise capacity – important! Eichenberger et al., 2013 19 latrobe.edu.au Physical activity participation Individuals with asthma:  Have reduced exercise capacity  Are less likely to engage in physical activity  Are less likely to engage in intense exercise But consider…  Physical activity can be a trigger for asthma symptoms  Associated with intolerance and fear  Status of asthma control is a key determinant 20 10  latrobe.edu.au Exercise-induced bronchoconstriction  Acute airway narrowing (transient and reversible) that occurs during or after exercise – ↓ in FEV1 of ≥10% from baseline following exercise – Occurs within 2−5 min post-exercise, peaks 10 min post-exercise, resolves in ~60 min.  Symptoms: dyspnoea, wheezing, cough, chest tightness, excessive mucus production, feeling of a lack of fitness despite good physical condition.  Prevalence: ~5−20% (general pop) – 30–70% in elite/Olympic level athletes – 3 to 35% in children ≤16 years old  Diagnosis: Exercise Challenge Test 21 latrobe.edu.au EIB, asthma, and exercise  EIB occurs in ~90% of individuals with asthma  Other risk factors: allergies, family history of asthma  EIB associated with ↓ exercise participation, ↓ QoL  Strong evidence for warm-ups to induce “refractory period” – 10-15 min variable intensity (light and vigorous intervals) – EIB occurrence is attenuated 22 11  latrobe.edu.au Exercise prescription Aerobic Resistance Frequency Minimally 3d/wk; preferably up to 5d/wk At least 2d/wk performed on non-consecutive days. Intensity Begin with moderate intensity (40%-59% HRR/VO2 max). Strength: 60%-70% 1RM (beginners) If well tolerated, progress to 60%-70% after 1 month. ≥80% 1RM (experienced) Endurance: