Respiratory System

1. Respiratory System John P. McDonough, CRNA, Ed.D., ARNP

2. Pulmonary System Structures • Lungs • Airways • (upper & lower) • Vasulature • Chest wall

3. Lungs • Right • upper, middle & lower • Left • upper & lower • Lobes  segment  lobules • Mediastinum • contains heart, great vessels, esophagus

4. Conducting Airways (upper) • Nasopharynx • Oropharynx • Laryngopharynx

5. Conducting Airways (lower) • Larynx • Trachea • divides at the carina • Bronchi

6. Conducting Airways (lower) • Lobar bronchi • Segmental bronchi • Subsegmental bronchi (nonrespiratory)

7. Gas Exchange Airways(Respiratory Unit) • Subsegmental bronchi (respiratory) • Terminal bronchioles • Alveolar ducts • Alveoli

8. Bronchial Walls • Epithelial lining • exocrine gland cells, ciliated cells • Smooth muscle • Connective tissue

9. Alveoli • 25 (birth)  300 (adulthood) million • Where most gas exchange takes place • alveolocapillary membrane • Secretes surfactant

10. Pulmonary Circulation • Facilitates gas exchange • Delivers nutrients to lung tissue • Reservoir for the left ventricle • Filter for the circulation • Less pressure & resistance than systemic • MAP 18 Vs 90 • 100 ml blood / 70-100 m2 • Bronchial circulation  pulmonary

11. Thoracic Cavity • Chest wall • Diaphragm • Lungs • Pleura • visceral & parietal • Mediastinum • Heart & great vessels

12. Volumes & Capacities • Alveolar dead space • Alveolar ventilation • Anatomic dead space • 1 ml / pound, 33% of each breath • Dead-space ventilation • Functional residual capacity • Minute volume

13. Volumes & Capacities(continued) • Physiologic dead space • Residual volume • Tidal volume • Total lung capacity • Vital capacity

14. Control of Ventilation • Voluntary Vs involuntary • Respiratory center (brain stem) • Chemoreceptors

15. Lung Receptors • Irritant • epithelium of conducting airways • Stretch (Herring-Breuer reflex) • smooth muscle of airways • J-receptors (juntapulmonary) • capillaries of alveolar septa

16. Chemoreceptors • Monitor pH, PaCO2 & PaO2 • Central chemoreceptors • near respiratory center • sense change in pH by H+ ion in CSF • Peripheral chemoreceptors • H+ changes  PaCO2 • CO2 + H2O  H2CO3 HCO3 + H+

17. Chemoreceptors(continued) •  ventilation  PaCO2 • CO2 diffuses across blood/brain barrier • H+  pH  • Center  rate & depth of respiration • Center sensitive to small changes (1-2 Torr) • Chronic disease will desensitize receptor

18. Chemoreceptors(continued) • Peripheral receptors • Aortic arch, aortic bodies, carotid bodies • Some sensitivity for PaCO2 & pH • Primarily react to PaO2 • Marked hypoxia (PaO2 <60 Torr) required

19. Mechanics of Breathing • Muscles are usually for inspiration only • 2 major muscles • intercostal & diaphragm • Accessory muscles • sternocleidomastoid & scalenes

20. Mechanics of Breathing(continued) • Alveolar surface tension • surfactant reduces it • Law of Laplace P= (2T/r) • Elasticity • Compliance

21. Airway Resistance(Poiseuille’s Law) • 50-66% occurs in the nose • Next highest, oropharynx & larynx • Should be little in lung conducting airways • Except in: • edema • obstruction • bronchospasm

22. Gas Transport • Intake of O2 by Ventilation of the lungs • Diffusion of O2 across PCM • Systemic capillaries get arterial blood • Diffusion of O2 into cell • Diffusion of CO2 into systemic capillaries • Pulmonary capillaries get venous blood • Removal of CO2 by ventilation of the lungs

23. Tests of Pulmonary Function • Spirometry • measures volumes and capacities • Diffusing capacity • measure ability for gas transport across PCM • Arterial blood gas analysis • Radiographs • chest x-ray

24. Arterial Blood Gases • Art Venous • pH 7.35-7.45 7.33-7.43 • PCO2 mm Hg 35-45 41-57 • PO2 mm Hg 80-100 35-40 • HCO3- mEq/L 22-26 24-28 • SO2 96-98% 70-75% • Base Excess -2 to +2 0 to +4

25. Effects of Aging • Loss of elastic recoil • Stiffening of the chest wall • Alterations in gas exchange • Increases in flow resistance • All influenced other factors • environmental, disease, body size, race & gender

26. S/S of Pulmonary Disease • Dyspnea • exertional, orthopnea, PND • Abnormal breathing patterns • Kussmaul, “purse lipped”, Cheyne-Stokes • Hypo/hyperventilation • Cough • Hemoptysis

27. S/S of Pulmonary Disease(continued) • Cyanosis • Pain • Clubbing • Abnormal sputum

28. Conditions Caused by Pulmonary Disease • Hypercapnia • Hyoxia • Acute respiratory failure • Pulmonary edema • Aspiration • Bronchiolitis

29. Conditions Caused by Pulmonary Disease (continued) • Pneumothorax • Plural effusion • Pulmonary fibrosis • Pneumoconiosis

30. Chronic Bronchitis • Occurs for at least 3 months, in 2 years • 20 X increase in smokers • Inflammation of bronchi (irritants/infection) • Muscle hypertrophy • Mucus gland hyperplasia • Inflammation • H. flu (Haemaphilus influenzae) & Streptococcus pneumoniae are common

31. Emphysema • Permanent  size of gas exchange airways • Destruction of alveolar walls • Obstruction from anatomical change • Primary- 1-2% of cases • 1-antitrypsin deficiency (70-80% likelihood) • Secondary most common

32. S/S of Emphysema • Dyspnea on exertion  at rest • Often no cough and little sputum • Thin patient • Tachypnea • Prolonged expiration

33. Chronic Obstructive Pulmonary Disease • Includes chronic bronchitis & emphysema • Next to heart disease as cause of death in adults <65 • >33% of all VA patients have COPD • smoking is the primary cause

34. Asthma • Reactive airways and bronchospasm • Extrinsic (most common) • mast cell activation • triggered by dust, mold, pollen, etc • Intrinsic • no known allergic cause • seen in adults >35 and often severe • triggered by drugs, irritants, infections, cold

35. Asthma(continued) • Inflammation  hyperresponsiveness • Thickening of airways • edema, vascular congestion,  mucus • Muscle (bronchial) spasm

36. Asthma(continued) • Sensation of chest constriction • Wheezing (inspiratory & expiratory) • Dyspnea • Cough (often non-productive) • Prolonged inspiration • Tachycardia • Tachypnea