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 lt60 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(Poiseuilles 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

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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

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S/S of Pulmonary Disease(continued)

• Cyanosis
• Pain
• Clubbing
• Abnormal sputum

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Conditions Caused by Pulmonary Disease

• Hypercapnia
• Hyoxia
• Acute respiratory failure
• Pulmonary edema
• Aspiration
• Bronchiolitis

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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
  lt65
• gt33 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 gt35 and often severe
• triggered by drugs, irritants, infections, cold

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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