Pulmonary System Physiology

1
(No Transcript)
2
Methods and Considerations in performing the FVC
test

• Deep breath
• Exhale Fast and forceful
• Nose clip
• Posture
• Guidelines set by ATS (American Thoracic Society)

3
Terminology

• FEV1
• FEV3
• FVC
• FEV1/FVC ratio

4
Lung Disease

• Obstructive Disease
• Decrease FEVI
• Decrease FEVI/FVC ratio
• Restrictive Disease
• Decrease FEVI
• Decrease FEV3
• Decrease FVC
• Normal FEVI/FVC ratio

5
Degrees of Obstructive Disease based upon
FEVI/FVC ratio
6
Functions Pulmonary System

• Exchange of carbon dioxide and oxygen
• Acid base balance
• Temperature homeostasis
• Filtering and metabolizing toxic substances

7
Overview

• Anatomy of the pulmonary system
• Muscles of ventilation
• Pulmonary Physiology
• Lung Volumes and Capacities
• Respiration/ Pulmonary Diffusion
• Ventilation and Perfusion
• Neurochemical Regulation of Breathing

8
Pulmonary Anatomy

• Bony Thorax
• Internal Structures
• Muscles of Ventilation

9
Bony Thorax

• Anterior border of the thorax
• Lateral border of the thorax
• Posterior border of the thorax
• Shoulder girdle

10
Internal Structures

• Upper Airways
• Nose
• Pharynx
• Larynx
• Lower airways
• Conducting airways
• The respiratory unit
• Lung structures
• Right lung
• Left lung
• Pleura
• Visceral, parietal, intrapleural space

11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
Muscles of Ventilation

• Inspiration
• Rest
• Exercise/ forced inspiration
• Expiration
• Rest
• Exercise/ forced expiration

15
Inspiration Muscles of ventilation

• Diaphragm (2 hemi diaphragms each with a central
  tendon)
• Arched high in the thorax at rest (dome) and
  pulled downward flattening the dome when
  contracted -gt protrusion of the abdominal wall
  during inhalation.
• External Intercostals
• Bucket handle movement of the rib cage.

16
Muscles of ventilation

• Diaphragm
• Highly fatigue resistant
• Contains a large volume of mitochondria and high
  levels of oxidative enzymes.
• Contraction increases cephalo-caudal,
  antero-posterior, lateral dimensions of the
  thorax.
• Length-tension relationship
• Effective functioning of the diaphragm depends on
  its shape.
• Diaphragm fatigue occurs when the capacity for
  force generation is compromised.

17
Accessory Muscles of ventilation

• Accessory muscles Used when a more rapid or
  deeper inhalation is required.
• Scalenes and SCM Raises upper 2 ribs
• Levator costarum and serratus Raises remaining
  ribs.
• Trapezius, pectorals, serratus fix the shoulder
  girdle.

18
Expiratory Muscles of ventilation

• Expiratory muscles of ventilation
• Resting exhalation A passive process achieved by
  elastic recoil of the lung.
• Expiratory muscles used when a more rapid and
  fuller expiration is needed
• Quadratus lumborum
• Internal Intercostals
• Abdominal muscles (T6 L1)

19
Clinical consideration

• What do you think happens with ventilation in
  patients who lack functional abdominal
  musculature?
• How can we assist breathing in this population?

20
Mechanics of breathing

• Inflation entails the inspiratory muscles
  overcome
• The tendency of the lung to recoil inward
• Resistance to flow offered by the airway
• Lung Distensibility/ Compliance
• A change in volume for a given change in
  pressure.
• Emphysema Compliance is high
• Pulmonary fibrosis Compliance is low

21
Respiratory Muscles

• Forces acting on the Rib cage
• Inspiratory muscle contraction -gt outward pull -gt
  Sub atmospheric alveolar pressure -gt Induces
  airflow into the lung.
• Following activation of the inspiratory muscles
  -gt lung expansion -gt elastic recoil -gt causes
  inward pull -gt balances outward forces -gt
  Expiration occurs as a passive process.

22
Respiration/ Pulmonary Diffusion

• Respiration Diffusion of gases across the
  alveolar capillary membrane
• Arterial oxygenation
• Alveolar ventilation

23
Pulmonary Diffusion

• Process by which gases are exchanged in the
  lungs.
• Amount of gas exchange depends on the partial
  pressure of each gas.
• Gases diffuse along a pressure gradient from
  areas of high concentration to areas of low
  concentration.

24
(No Transcript)
25
Arterial Oxygenation

• The ability of arterial blood to carry oxygen
• PaO2 /PO2
• Hyperoxemia
• Hypoxemia/ hypoxia
• SaO2 or SpO2
• FiO2
• Supplemental oxygen

26
Alveolar Ventilation

• Ability to remove CO2 from the pulmonary
  circulation and maintain pH
• pH 7.35-7.45
• P CO2 (35-45)
• Hypercapnia
• Hypocapnia
• H CO3 (22-28 meq/L)

27
Transport of Oxygen and Carbon Dioxide

• O2 is transported in the blood bound to
  hemoglobin (oxyhemoglobin).
• Hemoglobin O2 saturation decreases when
• PO2 decreases
• pH decreases
• Temperature increases
• CO2 is transported back to the lungs as
  bicarbonate ion.

28
(No Transcript)
29
Respiratory Regulation of Acid-Base Balance

• Excess H ions (low pH) impairs muscle
  performance.
• H ions stimulate inspiration.
• In addition excess H ions from increased
  lactate, may be buffered by bicarbonate ion,
  preventing acidosis.

30
(No Transcript)
31
Ventilation and Perfusion

• Optimal respiration occurs when ventilation and
  perfusion are matched.
• Types of ventilation perfusion relationships
• Dead space
• Shunt

32
Effects of body position on ventilation perfusion
relationship

• Upright position
• Perfusion
• Ventilation
• V/Q Ratio
• Other body positions

33
Control of Ventilation

• Receptors (Baroreceptors, chemo receptors,
  stretch receptors) adjust the ventilatory cycle
  by sending information to the controller.
• Central control center Cortex, pons, medulla,
  ANS
• Ventilatory muscles institute changes deemed
  necessary by the central controllers.

34
(No Transcript)
35
Terminology

• PaO2
• PaCO2
• ph
• HCO3
• Sa02

36
Normal ABG Values

• PaO2 gt80 mm Hg
• PaCO2 35-45 mm Hg
• ph 7.35 7.45
• HCO3 22 -28 mEq/L
• ABGs reported as
• PaO2/PaCO2/pH/HCO3

37
Terminology

• Hypoxemia
• PaO2 lt 80 mm Hg
• Hyperoxemia
• PaO2 gt 100 mm Hg
• Hypocapnia
• PaCO2 lt 35 mm Hg
• Hypercapnia
• PaCO2 gt 45 mm Hg

38
Terminology

• Acidosis
• pH lt 7.35
• Alkalosis
• pH gt 7.45
• Respiratory and Metabolic Processes
• Compensated vs. Uncompensated Processes
• Hypoxic Drive in Patients with COPD

39
Guidelines for ABG Interpretation

• Check the pH
• Examine the PCO2 determine if the pH change is
  due to a primary respiratory process.
• Examine the HCO3 - determine if the pH change is
  due to a primary metabolic process.
• Determine changes in PCO2 and HCO3 to see if the
  primary process has been compensated.

40
Acid Base Disturbances

• Respiratory Acidosis
• Respiratory Alkalosis
• Metabolic Acidosis
• Metabolic Alkalosis

41
Respiratory Acidosis

• pH Dec.
• PCO2 Inc.
• HCO3 WNL
• For every 10 pt. change in PCO2, there is a 0.08
  change in pH in the OPPOSITE direction.

42
Causes of Respiratory Acidosis

• Obstructive Lung Disease
• CNS depression with or without neuromuscular
  disorders
• Hypoventilation from pain, over sedation, chest
  wall deformities, secretion retention.
• Cardiopulmonary arrest

43
Respiratory Alkalosis

• pH Inc.
• PCO2 Dec.
• HCO3 WNL

44
Causes of Respiratory Alkalosis

• Hyperventilation from nervousness, anxiety,
  fever, pain, or mechanical ventilation.
• Hypoxia
• Pulmonary embolism, pulmonary fibrosis.
• Brain injury
• Congestive heart failure or hepatic insufficiency.

45
Metabolic Acidosis

• pH Dec.
• PCO2 WNL
• HCO3 Dec.
• For every 10 pt. change in HCO3, there is a 0.15
  change in pH in the SAME direction.

46
Causes of Metabolic Acidosis

• Diabetic ketoacidosis
• Lactic acidosis
• Renal failure, renal tubular acidosis

47
Metabolic Alkalosis

• pH Inc.
• PCO2 WNL
• HCO3 Inc.

48
Causes of Metabolic Alkalosis

• Fluid loss from upper GI tract (vomiting)
• Diuretic or corticosteroid therapy
• Severe potassium depletion
• Cushings disease, hyperaldosteronism.

49
Compensated Respiratory Acidosis

• pH WNL
• PCO2 Inc.
• HCO3 Inc.

50
Compensated Respiratory Alkalosis

• pH Inc.
• PCO2 Dec.
• HCO3 Dec.

51
ABGS in Decision Making

• 65 year old male with diagnosis of COPD.
  Currently SOB, SpO2 is 0.89. Should you only give
  2 L or higher FiO2?
• pH 7.33
• PaCO2 34
• PaO2 55

52
Interpret the following ABGs

• pH 7.35
• PaCO2 38
• HCO3 24

53
Interpret the following ABGs

• pH 7.21
• PaCO2 61
• HCO3 23

54
Interpret the following ABGs

• pH 7.54
• PaCO2 35
• HCO3 33

55
Interpret the following ABGs

• pH 7.33
• PaCO2 76
• HCO3 37

56
Interpret the following ABGs

• pH 7.20
• PaCO2 36
• HCO3 15

57
Interpret the following ABGs

• pH 7.29
• PaCO2 30
• HCO3 14

58
Pulmonary Pathophysiology 101

• Principle 2 Most of the variance in pulmonary
  disease is explained with a dichotomy.

59
Pulmonary Pathophysiology Dichotomy

• Obstructive Impairment
• Acute vs. Chronic
• If chronic reversible vs. irreversible
  components
• Restrictive Impairment
• Intra Pulmonary vs. Extra Pulmonary
• Acute vs. Chronic

60
COPD Statistics

• 12.1 million adults ages 25 and older reported
  being diagnosed with COPD in 2001.
• About 24 million adults have evidence of impaired
  lung function indicating that COPD is under
  diagnosed.
• About 726,000 hospitalizations for COPD occurred
  in 2000. More females than males were
  hospitalized for COPD (404,000 vs. 322,000).

National Center for Health Statistics., Maryland
U.S. Department of Health and Human Services,
CDC, NCHS. Vital and Health Stat 2(126), 1999.
61
Emphysema Chronic Bronchitis
62
Changes in peak VO2 (top left, A), peak VE (top
right, B), and peak VT standardized as percentage
of predicted vital capacity (bottom left, C)
during exercise and postbronchodilator FEV1
(bottom right, D) in 54 patients with COPD who
had complete data sets with no missing data every
6 months over 5 years
Oga, T. et al. Chest 200512862-69
63
Relationships between the change in peak VO2 and
the change in postbronchodilator FEV1 (left, A)
and between the change in peak VO2 and the change
in peak VE (right, B) in patients with COPD
Oga, T. et al. Chest 200512862-69
64
Pulmonary Pathophysiology

• Medical Tests extent of Impairment
  reversible/irreversible?
• VQ Scan Ventilation Perfusion Matching
• ABGs Respiration
• SpO2 Respiration
• CxR
• PFTs Ventilation Volumes and Flows
• FVC, FEV1, FEV1/FVC
• DLCO

65
Pneumonia - Definition

• A multistage inflammatory reaction of the distal
  airways from the inhalation of bacteria, viruses,
  microorganisms, foreign substances, gastric
  contents, chemicals, or as a complication of
  radiation therapy.

66
Pneumonia - Classification

• Community acquired pneumonia
• Nosocomial pneumonia

67
Phases of Pneumonia

• Alveolar edema with exudate formation.
• Alveolar infiltration with bacterial
  colonization, WBC, RBC, and macrophages
• Alveolar consolidation with dead bacteria, WBC,
  and fibrin.
• Resolution with expectoration or enzymatic
  digestion of infiltrative cells.

68
Types of Pneumonia

• Bacterial Pneumonia
• Viral Pneumonia
• Aspiration Pneumonia
• Pneumocystis carinii pneumonia

69
Bacterial Pneumonia

• Gram positive bacteria
• Streptococcal (pneumococcal)
• Gram negative bacteria
• Klebsiella, haemophilus, influenza, pseudomonas,
  aeruginosa, proteus, serratia.

70
Pertinent Findings

• Fever
• Shaking chills
• Chest pain if pleuritic involvement
• Productive cough purulent, blood streaked,
  rusty sputum.
• Breath sounds bronchial, crackles
• Tachypnea
• Increased WBC
• Hypoxemia

71
Viral Pneumonia

• Interstitial or intra-alveolar inflammatory
  process.
• Viral agents
• Influenza
• Cytomegalovirus
• Adenovirus
• Herpes
• Parainfluenza
• Measles

72
Pertinent Findings

• Recent history of URI
• Fever, chills, headache
• Dry cough
• Decreased breath sounds/ crackles
• Normal WBC
• Hypoxemia and hypocapnia
• Interstitial infiltrate on CXR

73
Aspiration Pneumonia

• Aspirated material causing an acute inflammatory
  process within the lungs.
• Seen in patients with impaired swallowing
  (dysphasia), impaired consciousness,
  neuromuscular diseases, recent anesthesia.

74
Pertinent Findings

• Symptoms may begin hours after aspiration.
• Cough Dry at onset -gt putrid secretions.
• Dyspnea, tachypnea
• Cyanosis
• Wheezes, crackles, dim. breath sounds.
• Hypoxemia
• Fever
• WBC with varying degrees of leukocytosis

75
Pneumocyctis carinii Pneumonia

• Pumonary infection casued by a protozoan in
  immunocompromised paatients.
• Often seen in patients with HIV
• Physical Findings
• Weakness
• Fever
• Non-productive cough
• Crackles
• Accompanied by weakness, fatigue

76
Pulmonary Assessment

• Patient Interview
• Physical Examination

77
Patient Interview
78
Physical Examination

• Vital signs
• Observation
• Auscultation
• Laboratory tests
• Radiographic examination

79
Vital signs

• Heart rate
• Blood pressure
• Temperature
• Respirations

80
Observation

• Breathing pattern
• Color

81
Auscultation

• Normal breath sounds
• Bronchial breath sounds
• Adventitious (extra) sounds
• Crackles
• Wheezes
• Rhonchi

82
Laboratory Tests

• ABG analysis
• Sputum studies
• Pulmonary function tests
• Lab values
• WBC
• Hematocrit
• Hemoglobin

83
Radiographic Examination

• Chest x-ray

84
Pneumonia
RUL Infiltrate
85
PA and Lateral View RML Pneumonia