呼吸衰竭RespiratoryFailure—英文课件.ppt

Respiratory Failure Dr. Sat Sharma Univ of Manitoba RESPIRATORY FAILURE “inability of the lung to meet the metabolic demands of the body. This can be from failure of tissue oxygenation and/or failure of CO2 homeostasis.” RESPIRATORY FAILURE Definition Respiration is gas exchange between the organism and its environment. Function of respiratory system is to transfer O2 from atmosphere to blood and remove CO2 from blood. Clinically Respiratory failure is defined as PaO2 60 mmHg while breathing air, or a PaCO2 50 mmHg. Respiratory system includes: CNS (medulla) Peripheral nervous system (phrenic nerve) Respiratory muscles Chest wall Lung Upper airway Bronchial tree Alveoli Pulmonary vasculature HYPOXEMIC RESPIRATORY FAILURE(TYPE 1) PaO2 60mmHg with normal or low PaCO2 ? normal or high pH Most common form of respiratory failure Lung disease is severe to interfere with pulmonary O2 exchange, but over all ventilation is maintained Physiologic causes: V/Q mismatch and shunt HYPOXEMIC RESPIRATORY FAILURE CAUSES OF ARTERIAL HYPOXEMIA 1. ?FiO2 2. Hypoventilation (? PaCO2) Hypercapnic 3. V/Q mismatch Respiratory failure (eg.COPD) 4. Diffusion limitation ? 5. Intrapulmonary shunt - pneumonia - Atelectasis