PHSI N303F Cardiopulmonary Physiotherapy Review PDF

PHSI N303F Cardiopulmonary Physiotherapy Review of Respiratory Physiology I Mechanics of Breathing Ms Eva Chan Senior Lecturer Department of Physiotherapy, HKMU 3 Sept 2024 Learning objectives After the lecture, you should be able to: r...

PHSI N303F Cardiopulmonary Physiotherapy Review of Respiratory Physiology I Mechanics of Breathing Ms Eva Chan Senior Lecturer Department of Physiotherapy, HKMU 3 Sept 2024 Learning objectives After the lecture, you should be able to: recognise the properties of the pulmonary structures and relation to their functions illustrate factors contributing to airflow resistance describe how inspiration and expiration take place by explaining the changes in pressure during respiratory cycle explain the regional difference in lung volume apply knowledge on breathing mechanics to pulmonary physiotherapy practice, including principles of airflow assessment and decision-making about choosing interventions involving positioning, breathing exercise, and secretion clearance HKMU Physiotherapy Revision on breathing Physiology Animations 2015 (hkmu.edu.hk) HKMU Physiotherapy ▪ Properties of the lung (Airway resistance, collateral ventilation, compliance, elastic recoil, surfactant) o Understand the terms o Respiratory mechanics o Clinical implications to physiotherapists HKMU Physiotherapy Airway resistance Resistance of respiratory tract to airflow during inspiration and expiration Calibre of the airways 1 Resistance α r4 Vicki Cobb Radius (=narrower) -> resistance carscoops HKMU Physiotherapy Bronchial smooth muscle Balanced activity between: Parasympathetic nervous system Bronchoconstriction Sympathetic nervous system bronchodilatation HKMU Physiotherapy Examples of pathological conditions reducing the calibre of the airways: Bronchoconstriction Secretion Mucosal oedema Tumour/mass Inhaled foreign body Loss of radial traction Citation: Chapter 7 Emergent General Medical Conditions, Gorse KM, Blanc RO, Feld F, Radelet M. Emergency Care in Athletic Training; 2010. Available at: https://fadavispt.mhmedical.com/content.aspx?bookid=2131&sectionid=159649978 HKMU Physiotherapy Collateral ventilation interalveolar (pores of Kohn) 1 - 2 μm bronchiole-alveolar (canals of Lambert) 25 - 30 μm interbronchial (channels of Martin) 80 - 150 μm (Main & Denehy , 2016) HKMU Physiotherapy  If there is NO airway bypass airway occlusion HKMU Physiotherapy  Clinical importance 1. Gas can find alternative routes to bypass obstructed airways 2. Increase lung volume, 8 recruit collateral ventilation, re-expand collapsed aveolli & airflow distal to plug → move the sputum more proximally version Incorporate with physiotherapy interventions Deep breathing with hold - Aid secretion removal - HKMU Physiotherapy Compliance > - Flexibility t Distensibility of an elastic structure Δ Pulmonary volume Δ Pressure Less compliant (stiff) at either extreme of lung volume (West & Luks, 2016) HKMU Physiotherapy Elastic recoil of the lung Fibers of elastin and collagen at alveolar walls and around vessels and bronchi resistance↑ T airway HKMU Physiotherapy Pulmonary surfactant A mixture of phospholipids and apoproteins Type II alveolar cells synthesize and secrete surfactant from 23 to 24 weeks’ gestation Visible Body HKMU Physiotherapy Pulmonary surfactant Reduce surface tension of liquid lining alveoli, thus preventing collapse of lung parenchyma Clinical significance: Insufficient surfactant -> reduced compliance (=stiff lungs), alveolar atelectasis, risk of developing pulmonary oedema Neonatal respiratory distress syndrome in premature infants freepik HKMU Physiotherapy Reduced compliance Increased compliance Large pressure is needed to increase the volume Pulmonary emphysema Increased fibrous tissue (pulmonary Aging fibrosis); alveolar edema Lung not being ventilated for long, especially having low lung volume (e.g. atelectasis) Reduced pulmonary surfactant HKMU Physiotherapy Extrapulmonary structures - reduced chest wall compliance: E.g. - Thoracic deformity - Raised intra-abdominal pressure Imagine how difficult you breath if you wear clothes of very small size HKMU Physiotherapy Work of breathing Work is done to move the lung and the chest wall to overcome resistive and elastic forces of airways, lungs and chest wall ─ Elastic resistance: 80% of the WOB ─ Airflow resistance: 20% of the WOB HKMU Physiotherapy How do patients present clinically if there is airflow limitation? Increased work of breathing SOB Wheeze Lowered O2 saturation HKMU Physiotherapy ▪ Properties of the lung (Airway resistance, collateral ventilation, compliance, elastic recoil, surfactant) ▪ Understand the terms o Respiratory mechanics o Clinical implications to physiotherapists HKMU Physiotherapy How does ventilation happen? Volume change Pressure change Gas flow HKMU Physiotherapy Human lung model https://www.kiwico.com/diy/stem/anatomy-biology/lung-model HKMU Physiotherapy Let’s answer the following questions 1. What happens to pressure inside a container if its volume increases? 2. Air flows from area of high / low pressure to that of high / low pressure. HKMU Physiotherapy P , V, = P2Vz Human Anatomy and Physiology HKMU Physiotherapy Human Anatomy and Physiology HKMU Physiotherapy Understand the terms Atmospheric pressure: pressure exerted by the gases in the air Intrapulmonary pressure or intra-alveolar pressure: pressure within the alveoli Intrapleural pressure: pressure within the pleural cavity Transpulmonary pressure: difference between the intrapulmonary and intrapleural pressures HKMU Physiotherapy  Freepik Lower pressure at higher altitude Freepik clipart-library Higher pressure under the sea HKMU Physiotherapy  (Always Negativeluny expan d Intrapleural pressure - - ↑ Averli expand Pal 17 -10 Pat1] -2.5 Weight of the lungs ↑ hydrostatic pressure HKMU Physiotherapy Clinical significance Pneumothorax: presence of air in the pleural space due to an abnormal communication between either the lung and the pleural space, or the atmosphere and the pleural space Citation: Chapter 27 The Thorax and -> lung collapse Abdomen, Prentice WE. Principles of Athletic Training: A Guide to Evidence-Based Clinical Practice, 17e; 2021. Available at: https://accessphysiotherapy.mhmedical.com/c ontent.aspx?bookid=2992&sectionid=2509639 98 Drain insertion to restore negative pressure HKMU Physiotherapy ▪ Properties of the lung (Airway resistance, collateral ventilation, compliance, elastic recoil, surfactant) ▪ Understand the terms ▪ Respiratory mechanics o Clinical implications to physiotherapists HKMU Physiotherapy Ventilation Inspiration: What happens to the intra-alveolar pressure? Rise or fall? Gas flows into the lungs Expiration: What happens to the intra-alveolar pressure? Rise or fall? Gas out of the lungs HKMU Physiotherapy Respiratory mechanics Citation: Chapter 9 Pulmonary Evaluation, DeTurk WE, Cahalin LP. Cardiovascular and Pulmonary Physical Therapy: An Evidence-Based Approach, 3e; 2017. Available at: https://accessphysiotherapy.mhmedical.com/content.aspx?bookid=2270&sectionid=176350331 HKMU Physiotherapy  Pre-inspiration Negative intrapleural pressure: tendency of the chest wall to expand outwards versus the tendency of the lungs to recoil inwards -5 0 Citation: Chapter 9 Pulmonary Evaluation, DeTurk WE, Cahalin LP. Cardiovascular and Pulmonary Physical Therapy: An Evidence-Based Approach, 3e; 2017. Available at: https://accessphysiotherapy.mhmedical.com/content.aspx?bookid=2270&sectionid=176350331 HKMU Physiotherapy  During inspiration End inspiration -2 0 -7 -8 Inspiratory muscles contract Air flow ceases when intra-alveolar -> thoracic cage diameter and lung volume pressure becomes equal to atmospheric increases pressure -> intra-alveolar pressure falls -> gas flows into the lungs HKMU Physiotherapy  During quiet expiration Inspiratory muscles relax and the lungs recoil passively -> reduces thoracic cage diameter and lung volume -> intra-alveolar pressure increases -> gas flows down the pressure gradient, from the lungs towards the mouth Gas flow will cease once intra-alveolar pressure becomes equal to atmospheric pressure HKMU Physiotherapy  Forced expiration Contraction of the expiratory muscles -> increases intrapleural pressure & intra-alveolar pressure +38 +30 HKMU Physiotherapy  Expiratory flow-volume curve Citation: Chapter 5 Pulmonary Physiology, kibble JD. The Big Picture Physiology: Medical Course & Step 1 Review, 2e; 2020. Available at: https://accessphysiotherapy.mhmedical.com/content.aspx?bookid=2914&sectionid=245544268 HKMU Physiotherapy Forced expiration at mid to low lung volume 0 28 30 Equal pressure point 32 +32 +30 HKMU Physiotherapy  0 33 35 37 +37 Exaggerated in patients with Using more effort +35 emphysema and those with severe obstructive lung disease more Pturbulence - - sputum  Phenomenon:- Dynamic compression of airways HKMU Physiotherapy ▪ Properties of the lung (Airway resistance, collateral ventilation, compliance, elastic recoil, surfactant) ▪ Understand the terms ▪ Respiratory mechanics ▪ Clinical implications to physiotherapists HKMU Physiotherapy Measurement of expiratory flow rate Spirometry - Forced expiratory volume (FEV1) - Forced vital capacity (FVC) Differentiation of restrictive versus obstructive diseases HKMU Physiotherapy  Positions of equal pressure points (EPP) Forced expiration at lung volumes above functional residual capacity (FRC) EPP: lobar/segmental bronchi EPP Forced expiration at decreasing lung volumes EPP: move distally into smaller more peripheral airways (Main & Denehy, 2016) HKMU Physiotherapy Forced expiration technique – huffing Principle component of Active Cycle Breathing Technique (ACBT) – combination of forced expiration and breathing control Huffing from mid to low lung volumes moves secretions from peripheral to more proximal airway Huffing from high lung volume or cough helps clear secretions from upper airway HKMU Physiotherapy Closing Volume When closing volume is reached, inspiration falls below the lower inflexion point on the pressure/volume curve a very large pressure is required to open airways and alveoli increase the work of breathing Closing volume increases with age, smoking, lung disease and position (supine > upright). HKMU Physiotherapy Positioning Based on the problems identified for the clients, you may position them to achieve certain goals of interventions like: ✓ To enhance the volume of particular side or part of the lung ✓ To improve matching of ventilation and perfusion ✓To achieve drainage of secretions HKMU Physiotherapy  Position: Upright Non-dependent -10 Alveolar size -2.5 Dependent HKMU Physiotherapy  Non-dependent Position: Side-lying Clinical implication: AEPHE > Alveolar size - If an adult patient suffers from atelectasis, to expand the affected lung more, the affected side can be put at the upper side (non-dependent) upon side-lying Dependent HKMU Physiotherapy  Supine vs prone lying Application in patients with acute respiratory distress syndrome (ARDS) Supine Prone https://www.researchgate.net/figure/Schemat ic-representation-of-strain-stress-distribution- and-its-impact-on-alveolar- size_fig3_283450861 HKMU Physiotherapy Challenges 1. Identify properties of the lung structures which constitute its compliance. 2. Illustrate the breathing mechanics with explanation of change of pressure. 3. Tell the indication of huffing and how it works. 4. Tell TWO indications of deep breathing exercise and how it works. HKMU Physiotherapy References Hough, A. (2018). Hough’s cardiorespiratory care: an evidence-based, problem-solving approach (Fifth edition.). Elsevier. Main, E., & Denehy, L. (Eds.). (2016). Cardiorespiratory physiotherapy : adults and paediatrics (Fifth edition.). Elsevier. West, J. B. & Luks, A. M. (2016). West’s respiratory physiology: the essentials (Tenth edition.). Wolters Kluwer. HKMU Physiotherapy