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PreClinEazy X Cardiff Medsoc Lung Physiology and Pathology Saad SiddiqueIn this session we’ll co ver Ventilation & Perfusion Types of Respiratory Failures Lung Pathologies • Ventilation is the amount of air going into the alveoli • Perfusion is the amount of blood flow going to the alveoli • Ventilation = (V) V entilation & Perfusion Perfusion = (Q) • V/Q ratio = Ventilation / Perfusion • Deadspace = Ventilation without perfusion. Can be anatomical or physiological. V/Q ratio = infinity Zones of the Lungs • Each zone has a different ventilation and perfusion rate • V/ Q ratio is higher at the apex • V / Q ratio is lower at the base • The ideal V/Q ratio is 1. Perfusion • Perfusion is lowest at the apex and highest at the base • This is due to gravity pulling blood down towards the base Ventilation of the Lungs • At the apex of the lung, the alveoli are larger because of the more negative intrapleural pressure • At the base, the alveoli are smaller because of the less negative intrapleural pressure. Ventilation • Ventilation is highest at the base and lowest at the apex. • This is because the alveoli are more compliant at the base than the apexRecap of V/Q ratios (in health) If ventilation and perfusion is greatest at the base and lowest at the apex, why do these regions not have the same V/Q ratio? At the apices of the lungs, ventilation is reduced, however the perfusion is far more reduced resulting in a high V/Q ratio. At the bases of the lung ventilation is greatest, however the perfusion is far more greater resulting in a high V/Q ratioAnother way to explain V/Q ratios Zone 1 : No blood flow and Pa Pv capillaries collapse PA Pa PA Pv Zone 2 : Pulsatile blood flow Pa Pv Zone 3 : Continuous blood flow Question 1 A 63-year old woman presents to the GP with extreme A The V/Q ratio increases shortness of breath when exercising or lying down. The patient is sent for a Chest X-Ray and an arterial blood gas test B The V/Q ratio stays the same confirms the patient has a pulmonary edema. C The V/Q ratio decreases What effect does a pulmonary edema have on the V/Q ratio? Question 1 A 63-year old woman presents to the GP with extreme A The V/Q ratio increases shortness of breath when exercising or lying down. The patient is sent for a Chest X-Ray and an arterial blood gas test B The V/Q ratio stays the same confirms the patient has a pulmonary edema. C The V/Q ratio decreases What effect does a pulmonary edema have on the V/Q ratio? Pneumonia - Consolidation in the COPD - Mucus thickening resulting lungs leading to reduced ventilation in greater diffusion distance V/Q ratio is low V/Q ratio is low V/Q Ratios (in Disease) COPD - Destruction of pulmonary Pulmonary Edema - Fluid Pulmonary Embolism - Clot occludes the pulmonary capillaries supplying the alveoli overload in the lungs capillary or pulmonary artery V/Q ratio is low V/Q ratio is high V/Q ratio is highRespiratory Failure • Respiratory Failure is failure of the respiratory system to perform gas exchange • Respiratory Failure results in hypoxaemia with or without hypercapnia • Type 1 = Oxygenation Failure Respiratory Failure • Type 2 = Ventilation Failure • Hypoxaemia = Low oxygen in arterial blood (< 8 mmHg) • Hypercapnia = High carbon dioxide in arterial blood (>6 mmHg) Type 1 RF • Low O2 and normal CO2 • PaO2 < 8 kPa • High CO2 with/without low O2 • PaCO2 > 6 kPa • Oxygenation Failure • Treat using Oxygen Therapy • Ventilation Failure • Cannot treat by simply giving oxygen. Patient requires ventilatory support. Type 2 RFAn 83-year old male presents to the Emergency department A) Type 1 Respiratory Failure - Respiratory with difficulty breathing and severe muscle pain. An ABG Muscle Weakness was conducted and shows that the patient has low O2 and normal CO2 levels. B) Type 2 Respiratory Failure - Kyphoscoliosis What type of respiratory failure does the patient have and what is the most likely cause? C) Type 2 Respiratory Failure - V/Q mismatch D) Type 1 Respiratory Failure - Sepsis E) Type 1 Respiratory Failure - Obesity A) Type 1 Respiratory Failure - Respiratory An 83-year old male presents to the Emergency department Muscle Weakness with difficulty breathing and severe muscle pain. An ABG was conducted and shows that the patient has low O2 and B) Type 2 Respiratory Failure - normal CO2 levels. Kyphoscoliosis What type of respiratory failure does the patient have and C) Type 2 Respiratory Failure - V/Q what is the most likely cause? mismatch D) Type 1 Respiratory Failure - Sepsis E) Type 1 Respiratory Failure - ObesityCauses of T ype 1 RF Causes of T ype 2 RF • Increased Oxygen Consumption, • Respiratory muscle weakness eg, exercise, sepsis • Chest wall deformities, eg, • Low Alveolar Oxygen Content obesity, kyphoscoliosis • V/Q mismatch • Depression of respiratory centre • Diffusion deficit, eg, pneumonia of the brain • Right to left Shunt, egVM and • Lung disease, eg, emphysema Patent Foramen Ovale and asthmaLung PathologiesA 54-year old man presents to the emergency A) Lung abscess department coughing up a mixture of foul smelling sputum and pus. Y ou order a chest X-ray and this is B) Empyema what you see. What is the patient’s diagnosis? C) Idiopathic pulmonary fibrosis D) Pneumonia E) Pulmonary edemaA 54-year old man presents to the emergency A) Lung abscess department coughing up a mixture of foul smelling sputum and pus. Y ou order a chest X-ray and this is B) Empyema what you see. What is the patient’s diagnosis? C) Idiopathic pulmonary fibrosis D) Pneumonia E) Pulmonary edema Pneumonia Lung Abscesses Empyema • Parenchymal lung • Localised • Infection in the inflammation collections of pus pleural cavity and • Caused by infection, in the lung not the lung itself predominantly parenchyma • Mainly treated using bacterial • Often develop a a chest drain • Radiological diagnosis cavitating necrotic based upon presence area in the centre of consolidationINSERT IMAGE HERE INSERT IMAGE HERE INSERT IMAGE HERE Pneumonia Lung Abscess EmpyemaPulmonary Fibrosis Pulmonary fibrosis (IPF) is a chronic disease affecting the tissue surrounding the alveoli, in the lungs. Pulmonary fibrosis leads to the lung tissue becoming thick and stiff for unknown reasons. References https://www.youtube.com/watch?v=-mL_NQ3pKnA https://www.webmd.com/lung/lung-abscess-overview https://www.nidirect.gov.uk/news/recognising-signs-and-sympto ms-sepsis https://www.nhlbi.nih.gov/health/idiopathic-pulmonary-fibrosis https://www.ajronline.org/doi/10.2214/AJR.10.4873PLEASE FILL OUT THE FEEDBACK FORM PLEASE TUNE IN TO OUR REMAINING SESSIONS THIS WEEK