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Ch.22 Respiratory physiology: the effects of anesthesia

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Title: Ch.22 Respiratory physiology: the effects of anesthesia


1
Ch.22 Respiratory physiologythe effects of
anesthesia
  • ??? 1?
  • ???

2
Cellular respiration
1.Aerobic metabolism 2.Anaerobic metabolism
  • ?? ?? ??? blood ? inspired air??? gas exchange?
    ?? ???, O2? ?? CO2? ??? ?? ?
  • 1. Aerobic Metabolism
  • O2? ????, energy? ???.
  • carbohydrates, proteins? two-carbon fragments
    (acetyl CoA) ? ????.? CO2? ???? ?? ??? energy?
    NAD, FAD, GTP? ????.? ????? Oxidative
    phosphorylation ? ?? adenosine triphosphate(ATP)
    ? ??
  • glucose  
  • C6H12O6 6O2    ?  6CO2 6H2O energy
  • energy ADP   P  ? 38 ATP ??
  • ?? ??? ?? ATP ?  ADP P energy
  • Cell? ATP ADP  10 1 ? ????.
  • ATP? ???? ?? ??? ?? ????, metabolic substrate? ??
    ???? ????? ???? ?

3
Cellular respiration
1.Aerobic metabolism 2.Anaerobic metabolism
  • Respiratory quotient (RQ)
  • ? total CO2 production(VCO2)? oxygen
    consumption (VO2)?? ??
  • RQ of carbohydrates, lipid, protein 1.0, 0.7,
    0.8
  • ?? ??? ?? VCO2 200mL/min  VO2 250mL/min? NL
    RQ  0.8
  • (????? protein? primary fuel source?
    ???? ???, fats? carbohydate combination??? ????.)
  • VO2    10(weight)
  • 2. Anaerobic Metabolism
  • 02? ???? ?? energy? ??
  • glucose? pyruvate, latic acid? ??? ??
  • ??? ?? ATP??(2ATP)
  • 3.Effects of Anesthesia on Cell Metabolism
  • ????? VO2? VCO2? ? ? 15?? ????
  • ?? ?? ??? ?? ??? ????

3/4
4
Functional respriatory anatomy
1.Rib musles 2.Trachea 3.Circulation 4.innervati
on
  • Rib Cage Muscles of Respiration
  • contraction of the diaphragm
  • the base of the thoracic cavity ? 1.5 -7cm ??
  • chest volume ??? 75
  • accessory respiration muscle? ??? ??? ??? ????.
  • ?? ??? ?????? ? ?, SCM, scalene, pectoralis
    muscle ??.
  • SCM rib cage?????? ??? ??.
  • scalene ??? upper rib? inward movement? ????.
  • pectoralis muscle chest expansion? ???.

5
Functional respriatory anatomy
1.Rib musles 2.Trachea 3.Circulation 4.innervati
on
  • Expiration? supine position ? passive?? ??????
    upright positoin ? active?? ????
  • Exhalation? abdominal muscles (rectus abdominis,
    external and internal oblique, transversus) ???
    internal intercostalis ? ???? ??? ?? ????.
  • some pharyngeal muscle airway patency ??? ??
  • genioglossus, levator palati, tensor palati,
    palatopharyngeus, palatoglossus  

6
Functional respriatory anatomy
1.Rib musles 2.Trachea 3.Circulation 4.innervati
on
  • 2. Tracheobronchial Tree
  • ? ??? ?? alveoli? gas? ??
  • ? ??? ??? ?? trachea??
    alveolar sacs?? 23
    division? ??.
  • alveolar sac? 17 alveoli? ?? ? 3???
    alveoli? 50-100m2 ???
    membrane ? ??.
  • Mucosa? ??? ciliated columnar? ???? ??
    cuboidal??? ?????
    alveolar epithelium? ??.
  • gas exchange flat epithelium
  • ??? ?? smaller airways? patency? ??
    ??? elastic recoil?
    radial traction? ???? ??.

7
Functional respriatory anatomy
1.Rib musles 2.Trachea 3.Circulation 4.innervati
on
  • Alveoli
  • Alveolus ?? ??   0.05-0.33 mm
  • in supine, largest alveolar apex  ,smallest
    base
  • inspiration? alveolar size? ?????.
  • respiratory epithelium two cell type
  1. type ?pneumocyte flat ?? tight junction ? ????
    albumin ?? oncotically  active molecules ? ???
    ???? ??? ??.
  • type ? pneumocyte round cell?? cytoplasmic
    inclusion(lamellar bodies)? ???? surfactant?? ???
    ????. ?? cell division ? ?? type?pneumocyte,
    alveolar macrophages, mast cells, lymphocytes,
    and APUD cell, Neutrophils? ????.

8
Functional respriatory anatomy
1.Rib musles 2.Trachea 3.Circulation 4.innervati
on
  • ??? alveolus? wall? ???? ??
  • thin side (lt 0.4? )
  • gas exchange? ??,
  • alveolar epithelium
  • capillary endothelium
  • thick side (interstitial space)
  • fluid and solute exchange ??
  • pulmonary interstitial space ?
  • ?? elastin, collagen, ??? nerve fibers ?
    ????.
  • ??? 1-2?? alveolus? structural support ? ????.

9
Functional respriatory anatomy
1.Rib musles 2.Trachea 3.Circulation 4.innervati
on
  • 3. Pulmonary Circulation Lymphatics
  • ?? two circulations? ????
  • bronchial circulation
  • Lt heart?? ??
  • Trachea???? pumonary bornchioles ?? support ?.
  • pulmonary circulation
  • Rt heart ?? pulmonary artery? ?? bronchus? ?? ??.
  • ?? ????? CO2? ???? O2? ?? four main pulmonary
    veins? ?? left heart ? ????.
  • Two circulation ??? direct connection? ??
  • ???? ?? ??? ?? ???? ??? ??? ??? ?.

10
Functional respriatory anatomy
  • Pulmonary Capillaries
  • ????? ?? ?? ??? pulmonary circulation??
    capillary network? ?? ??? ??? alveolar size ? ??
    ?? ???.
  • pulmonary capillary endothelium? 5nm ?? ????? ?
    ??? ??? ?? albumin?? ? molecules ? ??? ????
  • alveoli? ?? ?? ??? Macrophages? ?? bacterial
    infection? ???? foreign particles ? ?????.

11
Functional respriatory anatomy
  • Pulmonary Lymphatics
  • Interstitial spaces?? ????
  • Lymph nodes ? tracheobronchial chain? ????
    airways? ?? ???? ????.
  • ?  ? ?? ??? drainage channels? trachea? ????
  • left lung?? ?? fluid? ?? thoracic duct ? ?????
  • ?? right lung ?? ?? ?? right lymphatic duct ?
    ????.

12
Functional respriatory anatomy
1.Rib musles 2.Trachea 3.Circulation 4.innervati
on
  •  4.Innervation
  • Diaphragm? phrenic nerves (C3-C5 nerve roots) ?
    ??
  • unilateral phrenic nere block? ? 25?? pulmonary
    function??
  • accessory muscle activity
  • intercostal muscle ? ?? ??? thoracic nerve roots?
    ??
  • vagus nerves ? tracheobronchial tree? ????? ??
  • bronchial smooth muscle ? secretory gland? ?????
    ?? ??
  • vagal activity bronchoconstriction , bronchial
    secretion ??
  • sympathetic activity (T1-T4) bronchodilation, se
    cretion ??
  • nonadrenergic, nonchoinergic bronchodilator
    system? ???
  • a- and ß- adrenergic receptors? pulmonary
    vasculature ? ?????  pulmonary vascular tone? ??
    effect ? ???

13
 BASIC MECHANISM OF BREATHING
  • Reoxygenates desaturated blood eliminate CO2
  • Exchange of alveolar gas ??? ??? small cyclic
    pr. gradient ? ?? ????.

14
 BASIC MECHANISM OF BREATHING
  • Spontaneous Ventilation
  • spontaneous breathing?? normal pressure
    variation? ????.
  • Pressure alveoli ? ? gt surrounding
    (intrathoracic) pressure
  • pleural pressure ? intrathoracic pressure ?? ?
    ????.  
  •        P transpulmonary  Palveolar  -
    Pintrapleural
  • Inspiration? chest ? ???? intrapleural pressure?
    -5cmH2O ?? -8 or 9cmH2O? ??    ? ????? alveolar
    pr.??, ??? alveolar-upper airway gradient ??
  • expiration?, returns intrapleural pressure to
    -5cmH2O
  • elastic recoil of lung reversal of
    alveolar-upper airway gradient ? ????.

15
 BASIC MECHANISM OF BREATHING
  • Spontaneous Ventilation
  • spontaneous breathing?? normal pressure
    variation? ????.
  • Pressure alveoli ? ? gt surrounding
    (intrathoracic) pressure
  • pleural pressure ? intrathoracic pressure ?? ?
    ????.  
  •        P transpulmonary  Palveolar  -
    Pintrapleural
  • Inspiration? chest ? ???? intrapleural pressure?
    -5cmH2O ?? -8 or 9cmH2O? ??    ? ????? alveolar
    pr.??, ??? alveolar-upper airway gradient ??
  • expiration?, returns intrapleural pressure to
    -5cmH2O
  • elastic recoil of lung reversal of
    alveolar-upper airway gradient ? ????.

16
BASIC MECHANISM OF BREATHING
  • Mechanical Ventilation
  • Positive airway pressure? ????.
  • Inspiration?, upper airway? ??? ??? ??? alveoli?
    gas flow ??
  • Expiratory phase of the ventilator? positive
    pressure? ???? ???? gas? alveoli ??? ???.
  • Respiratory Pattern? ?? Anesthesia ? ??
  • Position? anesthetic agents ? ?? ???.
  • supine position?, abdominal breathing predominate
  • ????? ??? ???? light anesthesia? irregular
    breathing patterns? ????.
  • inhalation agent rapid shallow
  • nitrous-narcotic slow deep
  • Induction? expiratory muscles? ????? expiration
    becomes active
  • Inhalation agent? RR? ?? ??? tidal volume? ????

17
MECHANICS OF VENTILATION
  • ?? ??? ????? ?????, respiratory system? ??? ??
    ????.
  • Respiratory system? elastic resistance ?
    gas-liquid ???, ??? nonelastic resistance? ???.
  • Elastic resistance of tissue ? gas-liquid ???
    gas flow ? ?? static condition ???? lung
    volume?  pressure ??.
  • elastic resistance? ???? ?(work)? energy? ??? ??
    ?? ??? energy? ????? ???
  • Nonelastic resistance to gas flow  air flow ?
    tissue deformation? ?? ?? ??? ????.
  • nonelastic resistance? ????? ??? energy? ?? ????.

18
MECHANICS OF VENTILATION
  • 1.Elastic Resistance
  • Lung? chest ? elastic properties? ???.
  • chest? expand outward ??? ,?? lung? collapse???
    ??? ??
  • recoil properties of the chest deformation? ??
    ????? ??? ??? ??
  • recoil properties of the lung elastin fiber? ??
    ? ??? ?? alveoli?? ?? air-fluid ???? ??????.  
  •  
  • Surface Tension Forces (????)
  • alveoli? ?? ?? gas-fluid ???? ??? bubbles?? ??
  • surface tension forces? interface? ??? ???
    alveolar collapse? ????.
  • pressure 2 surface tension
  •                                radius
  • alveolar??   alveolar collapse ??? pressure ?
    surface tension? ???? alveolar size? ?????. (?
    surface tension? ???, alveolar size? ??? ??)
  • pulmonary surfactant ? ?? surface tension? ????
    (??? ????)  lung? collapse ??

? Surfactant? ? ???.
19
MECHANICS OF VENTILATION
  • Compliance
  • elastic recoil ???? ??
  • (change in volumue divided by change in
    distending pressure)
  • supine position chest wall compliance
    ??(abdominal contents? ???)
  • lung compliance is defined as
  •      CL           change in lung
    volume
  •                            change in
    transpulmonary pressure
  •       normal 150-200mL/cm H2O
  •       lung volume, pulmonary blood volume,
    extravascular lung water, inflammation and
    fibrosis?? ?? ??? ?? ??? ???.
  • Chest wall compliance       change in chest
    volume
  •                                     
    change in transthoracic pressure
  •        normal 200mL/cm H2O
  • total compliance (lung and chest wall together)
    100mL/cm H2O
  •  1             1          1
  • Ctotal            CW            CL

20
MECHANICS OF VENTILATION
  • 2.Lung Volumes
  • ????? ???? important parameter
  • lung capacities? ????? ??? ????? 2?? ? ???
    volume? ???? ????.

21
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22
MECHANICS OF VENTILATION
  • Functional Residual Capacity
  • ?? ?? ???? lung volume
  • ?? lung? inward elastic recoil ? chest? outward
    elastic recoil? ?????.
  • nitrogen wash-out or helium wash ,body
    plethysmography? ??
  • FRC ? ????? ??
  • Body habitus height? ??, obesity? ???
  • sex ???? 10 ??
  • posture supine or prone position? ??
  • lung disease lung, chest? compliance? ???? ??,
    restrictive pulmonary disorder?? ??
  • diaphragmatic tone 

23
MECHANICS OF VENTILATION
  • Closing Capacity
  • small airway? cartilaginous support? ??, ?? ???
    radial traction? ?? airway? ?? ??.
  • lung? basal area?? patency(???)? lung volume? ??
  • closing capacity? ?? airway? ?? ??? ?? volume
  • tracer gas(Xenon133)?? ??
  • ?? FRC?? ??
  • posture? ??? ?? ???    
  • age? ?? ??
  • Vital Capacity
  • ?? ?? ? ??? ? ?? ???
  • body habitus, respiratory muscle strength and
    chest lung compliance? ??
  • normal 60-70mL/Kg

FRCclosing capacity 44?
24
MECHANICS OF VENTILATION
  • 3. Nonelastic Resistances
  • Airway Resistance to Gas Flow
  • ???? gas flow? laminar flow? turbulent flow? ???
    ??? ??
  • laminar flow ?? ?? ??? ?? ?? ?? gas flow? ?? ??
    ?? ??
  •             Flow      Pressure gradient
  •                               Raw(airway
    resistance)               
  •             Raw     8 Length Gas viscosity
  •                             p (Radius)4
  • turbulent flow ???? ???? gas flow ? ??
  •           Pressure gradient  flow2 Gas
    density
  •                                      
    Radius5
  • Resistance gas flow? gas density? ??,
  • Radius? 5???
    ???(airway caliber? ??)

25
MECHANICS OF VENTILATION
  • Turbulent or laminar flow ??? Reynold number?
    ????
  •    Reynold number linear velocity
    diameter gas density
  •                               
     gas viscosity
  • laminar flow lt1000   only distal to small
    bronchioles(lt1mm)   
  • turbulent flow gt1500   larger airway
  • total airway resistance 0.5-2 Cm H2O/L/s
  • medium sized bronchi (before 7th generation)? ??
    ?? ???
  • airway resistance ??? ??
  • bronchospam, secretion, mucosal edema
  • volume-related flow-related airway collapse

26
MECHANICS OF VENTILATION
??? 1??? ??? volume
??? 2575 ?? ??? volume
  • A. Volume-Related Airway Collapse
  • at low lung volume (loss of radial traction)
    small airway ? resistance ??? airway resistance?
    ??? lung volume? ???
  • B. Flow-Related Airway Collapse
  • forced exhalation??, ???? transmural airway
    pressure? ??? airway collapse? ??? ? ?? (dynamic
    airway compression)
  • two contributing factors
  • generation of a positive pleural pressure
  • a large pressure drop across intrathoracic airway
  • equal pressure point dynamic compression? ????
    airway point? ??
  • ????? cartilagenous support? ?? 11th generation
    of bronchioles??
  • Emphysema, asthma ??? ??
  • A. Forced vital Capacity
  • ??? ??? ? ??? ??? ???? ??? ?? ??? ?? ??? ???
    ????.
  • FEV1/FVC airway obstruction? ??? ??
  • ????? FEV1/FVC gt 80
  • FEV1 FVC effort-dependent
  • FEF25-75 effort independent, ? ??? ? ??
    obstruction measurement

27
MECHANICS OF VENTILATION
  • 4.Work of Breathing (WOB)
  • ??? ????? ??????, ??? ??? WOB? inspiratory
    muscle(primarily diaphragm)? ?? ??? ??.
  • Ventilation ?? ??? resistance? ???? ??.
  • 1. elastic recoil of the chest lung
  • 2. frictional resistance to gas flow
  • 3. tissue frictional resistance
  • Respiratory muscle? ?? ?? ???? 23? ???? ?? ???
    ???? 10? ????, ??? 90? ?? ??
  • due to elastic airflow resistance

28
MECHANICS OF VENTILATION
  • 5. Effects of Anesthesia on Pulmonary Mechanics
  • Effects on Lung Volume Compliance
  • Induction supine position ?? additional 15-20
    reduction in FRC (400mL in most patients) - loss
    of normal end-expiratory diaphragmatic tone
  • Closing capacity ?? ??? ???? ????
  • Effects on Airway Resistance
  • FRC? ??? airway resistance? ???? ??? ???? ??????
    bronchodilating properties? ???? ???
  • Effects on the Work of Breathing   
  • ?? ? work of breathing? ??? lung chest wall
    compliance? ???? ?? ????.

29
VENTILATION/PERFUSION RELATIONSHIPS
  • 1.Ventilation
  • Minute ventilation(?? ???) respirtory rate
    tidal volume (VT)
  • alveolar ventilation(VA) respiratory rate (VT
    - VD)
  • Dead space ( VD) tidal volume (VT) ??? gas
    exchange? ???? ?? ??
  • physiologic anatomic dead space    alveolar
    dead space
  •   (nonrespiratory
    airway)  (not perfused alveolar)
  • ????? 150mL (?? 2mL/kg)
  • ???? tidal volume? ? 450mL ???
  •      VD         PACO2  - PECO2        33
  •      VT               PACO2  
  •   ( PACO2 alveolar CO2,  PECO2 mixed expired
    co tension)

30
VENTILATION/PERFUSION RELATIONSHIPS
  • Distribution of Ventilation
  • Ventilation? ?? ?? ??? ???? ????? ???.
  • right  lung  gt  left lung (53 47)
  • lower area (dependent)  gt upper area 
    (transpulmonary pr.? ??)
  • Upper lung area? alveoli? ??? ???? ??, ??? non
    compliant ?
  • Lower lung area(Dependent area)? smaller alveoli?
    ? ? compliant ??? expansion? ? ?
  • ?? ??? pulmonary ventilation? ??? ??
  • ???? ????? ????? ???? ??. ??? ????? ???? ??
    compliance? resistance ? ? ???? ????? alveolar
    filling? ????? ????? ???.

31
VENTILATION/PERFUSION RELATIONSHIPS
  • 2. Pulmonary Perfusion
  • ?? ?? 5L/min? ?? ????, ??? 70-100mL? gas
    exchange? ???? ?? pulmonary capillary? ??.
  • capillary volume? ??? ?????? total pulmonary
    blood volume? 500-1000mL  ???? ?? ? ??.
  • supine position?? erect ?? 27???? pul. blood
    volume ??

32
VENTILATION/PERFUSION RELATIONSHIPS
  • Pul. vascular tone? ?? ?? local factor?
    autonomic sys. ?? ????
  • Pul. arterial alveolar hypoxia? Pul.
    vasoconstriction
  • leukotrienes ??, NO ????? ???
  • Intrapulmonary shunting? ?? hypoxemia? ????.
  • hypercapnia acidosis vasocontstrictor effect
    (hypocapnia?? vasodilate)

33
VENTILATION/PERFUSION RELATIONSHIPS
  • Distribution of Pulmonary Perfusion
  • lower (dependent) portion  gt upper portion
  • zone 1 alveolar dead space 
  • ? PAgtPagt Pv ? ???? ???? pul.capill? ??? ??
  • zone 2 arterial-alveolar pressure gradient? ??
  • zone 3 arterial-venous pressure gradient? ??
  • Ventilation/Perfusion Ratios
  • alveolar ventilation (VA) 4L/min     pulmonary
    capillary perfusion 5L/min
  • ? V/Q rate 0.8 (0 (no ventilation) - ???(no
    perfusion))
  • no ventilation
    intrapulmonary shunt
  •      0.3  lt  V/Q lt 3.0
  • V/Q ratio? ??? ?? ???? O2? resaturated ???.
    CO2? ???? ???? ??

34
VENTILATION/PERFUSION RELATIONSHIPS
  • Ventilation/Perfusion Ratios
  • alveolar ventilation (VA) 4L/min    
  • pulmonary capillary perfusion 5L/min
  • ? V/Q ratio 0.8
  • (0 (no
    ventilation) - ???(no perfusion))
  •    normal   0.3  lt  V/Q lt 3.0
  • V/Q ratio? ??? ???? resaturated ???. CO2?
    ?????
  • ?? ??
    ???? ???

35
VENTILATION/PERFUSION RELATIONSHIPS
  • 3.Shunts
  • Shunt ???? ?? mixed venous blood? ????? ?????
    ????? ?? ?? (right to left shunt)
  • Absolute shunt anatomic shunt V/Q is zero
  • Relative shunt low but finite V/Q ratio

36
VENTILATION/PERFUSION RELATIONSHIPS
  • Venous Admixture
  • pulmonary end-capillary blood? artery?? oxygen
    tension??? ???? ?? ????, pulmonary end-capillary
    blood? ????? ?? mixed venous blood? ?? ???
  • venous admixture (Qs)? total cardiac output (QT)?
    ??? ??
  •    QS                 CcO2  -  CaO2
  •    QT                   CcO2  -  CvO2
  • CcO2 ???? pulmonary end-capillary bl.? oxygen
    content
  • CaO2 arterial oxygen content
  • CvO2 mixed venous content
  • ?? Qs/ QT?  deep bronchial vein? pulmonary vein,
    thebesian circulation, low V/Q ratio ?? ?? lung
    area?? communication? ?? ??
  • ???? venous admixture? 5???? shunt ?? ?? ??
    ????.

37
VENTILATION/PERFUSION RELATIONSHIPS
  • 4.Effects of Anesthesia on Gas Exchange
  • Dead space
  • Hypoventilation
  • Intrapulmonary shunt? ?????.
  • ?? ?? ? ??? ?? atelectasis? airway collapse? ?
    ???? ?? ?? ?? venous admixture? 5-10 ???? .

38
VENTILATION/PERFUSION RELATIONSHIPS
  • NO? ??? inhalation agents? high dose?? hypoxic
    pulm.vasoconstriction? ???? hypoxemia? ????
    ? ??, O2 tension? 3040 ?? hypoxemia ? ????,
    PEEP? venous admixture? ?????.
  • ??? high inspired oxygen concentration(gt50)? ???
    absolute shunt? ???? ? ??.

39
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  •  gas? ??? ?? ??? gas pressure? ??? ????.
  •     PIO2 PB x FiO2
  • 159.6mmHg 760mmHg x 0.21
  • PB barometric pr. 
  • FiO2 inspirarted oxygen? ??
  • ?? x 7? mmHg? ??? ? ??
  • kilopascal? ??? ?? ??

40
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  • I. Oxygen
  • Alveolar Oxygen Tension (PAO2)
  • ?? ? ??? gas? humidification ?? ??? ??? inspired
    tension? ????? ??
  •            PIO2 (PB -PH2O) FiO2
  • alveoli?? ??? gas? ?? ???? alveolar gas(O2, CO2)?
    ????. ???
  •            PAO2 PIO2 -PaCO2/RQ
  • PaCO2 arterial CO2 tension, RQ respiratory
    quotient
  • Inspired oxygen concentration() x 6 PAO2 mmHg

41
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  • Pulmonary End-Capillary Oxygen Tension (PcO2)
  • ????? PcO2 PAO2
  • PcO2 (pul.end-capil.O2 tension)
    alveolar-capillary membrane ??? oxygen diffusion
    rate? pulmonary capillary blood volume transit
    time? ?? ??
  •      capillary transit time pulmonary capillary
    blood volume
  •                                      
    cardiac output
  •                                70mL / 
    5000mL/min   (0.8sec)
  • alveolar gas??? blood? ?? ????? ?? rate-limiting
    factor
  • ? O2? Hb ??? ??

42
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  • pulmonary diffusing capacity
  • alveolar-capillary membrane?
    permeability
  • pulmonary blood flow? ?? 
  •                
  • alveolar-capillary membrane?? ?? ??? oxygen
    diffusing capacity(DLO2)? ??
  •           DLO2      oxygen uptake
  •                         PAO2 PcO2
  • PcO2? ??? ??? ? ?? DLCO? ?? ??
  •           DLCO       carbon monoxide uptake
  •                              PACO  -PcCO
  • DLCO? ??? alveolar capillary memb.? ?? gas
    transfer? ??? ??
  • due to abnormal V/Q ratio, destruction of
    alveolar-capillary membrane, short capillary
    transit time

43
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  • Arterial Oxygen Tension (PaO2)
  • alveolar-arterial oxygen partial gradient(A-a
    gradient)? 15mmHg????
  • ??? ?? ?? 20-30mmHg? ??   
  • PaO2      102 -age/3  
  • noraml range 60-110mmHg(8-13kPa)
  • ??? FRC? ?? ???? closing capacity? ??? ??? ??   

44
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  • Arterial Oxygen Tension (PaO2)
  •   
  • hypoxemia? ?? ?? ??? alveolar-arterial
    gradient??? ??
  • A-a gradient ? right to left shunt, V/Q scatter?
    ??, mixed venous oxygen tension?? ?? ??
  • A-a gradient? shunt? ?? ???? mixed venous
    tension? ???
  • oxygen ??? hemoglobin ??? ?? PaO2? ??? ???
    (high oxygen consumption low hemoglobin
    concentration? A-a gradient? ????, PaO2? ????)

45
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  • Mixed Venous Oxygen Tension (PvO2)
  • SVC, IVC, heart? ???? vein ?? ???? ?? ??
  • normal 40mmHg
  • ?? oxygen consumption oxygen delivery? ???
    ??? ????.
  • pul. artery catheter? ?? ? ? ??.

46
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  • 2.Carbon Dioxide
  • Mitochondria?? aerobic metabolism? ? ???
  • Mixed Venous Carbon Dioxide Tension (PvCO2)
  • normal 46mmHg
  • ??? ???? ?? ??????? blood? ??? ??
  • Alveolar Carbon Dioxide Tension (PACO2)
  • Total CO2 ??? alveolar ventilation(CO2 ??)??
    balance? ????.
  •                PACO2     VCO2
  •                               VA
  • PACO2 ? CO2 ???? CO2 ??? ? ???
  • ???? ???? ??, CO2 ???? ?? ?? ???? ??, ?? ?? CO2 ?
    ?? ? ????? ? ? ?? ??? ?? ??? PACO2? alveolar
    ventilation? ? ???? ??

47
ALVEOLAR, ATERIAL VENOUS GAS TENSIONS
  • Pulmonary End-Capillary Carbon Dioxide Tension
    (PcCO2)
  • PcCO2 PACO2
  • alveolar-capillary membrane? ?? CO2 diffusion
    rate? ??? 2???
  • Arterial Carbon Dioxide Tension (PaCO2)
  • normal PaCO2? 38 /- 4mmmHg ( 5.1 0.5KPa)
  • ???? arterial to alveolar gradient? ??? V/Q
    abnormality ??? ??? 
  • End-Tidal Carbon Dioxide Tension(PETCO2)
  • end-tidal CO2 tension? ????? PaCO2? ?? ?? ??
  • PACO2-PETCO2 gradient? 5mmHg ??

48
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • 1.Oxygen
  • 2 form?? ?? solution? ?? ???, hemoglobin? ?????
    association?
  • Dissolved Oxygen
  • ?? ???? ?? ???? ??? Herney's law? ?? ?? ? ??. 
  •          Gas concentration    a partial
    pressure
  •                a ??? ??? ??? ????? gas ?? ??
  • ?? ????? ?? 0.003mL/dL/mmHg
  • Hemoglobin
  • 4?? heme? 4?? protein subunit?? ??? complex large
    molecule
  • Heme oxygen-binding site? essential part? iron
    porphyrin compound
  • ?? hemoglobin molecule (hemoglobin A1)
  • 2?? a- 2?? ß-chain?? ??
  • 4?? subunit? amino acid residue?? weak bond? ??
  • hemoglobin 1g? 1.39mL? ??? ?? ? ??.

49
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • Hemoglobin Dissociation Curve
  • ? hemoglobin ? 4?? ????? ???
  • hemoglobin saturation? Hb? ??? ??? ? ?? O2 ? ??
    ??? Hb? ??? O2? ?? percent? ??
  • ?? 3?? ?? ??? ??? 4?? ?? ??? ????
  • Saturation? 90 ??? ??? ?? ??? oxygen receptor?
    ???? curve? flatten ?? ??.

50
TRANSPORT OF RESPIRATORY GASES IN BLOOD
Alkalosis Hypothermia 2,3-DPG??
  • Factors influencing the Hemoglobin Dissociation
    Curve
  • Hydrogen ion concentration
  • CO2 tension
  • Temperature
  • 2,3-diphosphoglyceride (2,3-DPG)concentration
  • P50 hemoglobin? 50? ???? oxygen tension
  • shift to right (increasing P50)
  • make more oxygen available to tissue
  • shift to left (decreasing P50)
  • oxygen affinity ??, reducing availablity to
    tissue
  • normal P50 26.6mmHg(3.4kPa)

Acidosis Hyperthermia 2,3-DPG??
P50
Affinity? ?? O2 release to tissue O2 uptake? ??
??.
26.6mmHg
51
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • Abnormal Ligands Abnormal Forms of Hemoglobins
  • carbon monoxide, cyanide, nitric acid, ammonia ??
    ?? ?? hemoglobin? ??? ? ?? (shift to left)
  • ?carbon monoxide 200-300? ??
  • ?carboxyhemoglobin? ??
  • methemoglobin heme? ?? iron? trivalent form??
    ??(?? ?? ??)
  • methylene blue or ascorbic acid? methemoglobin??
    Hb??? ??? ????.
  • abnormal hemoglobin protein subunit
    composition? variation? ?? ??
  • fetal hemoglobin, hemoglobin A2. sick hemoglobin

52
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • Oxygen Content
  • Total O2 content solution? ?? ?? ?? hemoglobin?
    ?? ???? ?? ?
  • oxygen content (0.003mL O2/dL blood/mmHg)
    PO2
  •                          
    (SO2 Hb 1.31mL/dL blood)
  • CaO2 19.5mL/dL blood     CvO2 14.8mL/dL blood
  • ???, arteriovenous difference? ?? ? ??.
  • CaO2 -CvO2 4.7mL/dL

53
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • Oxygen Transport
  • respiratory circulatory function? ?? ??
  • Total oxygen delivery to tissue(DO2) arterial
    oxygen content cardiac output (QT)
  • DO2 20mL O2/dL blood 50dLper blood/min
  •           1000mL O2/min 
  • Frick equation? ?? ??, ?? ?, ? ??? ?? ??? ????
  •         oxygen consumption   VO2   QT (CaO2 -
    CvO2)
  •                   CaO2    VO2        CvO2
  •                               QT
  • extraction fraction (CaO2- CvO2)/ CaO2 5/20
    25
  • ??? hemoglobin? ??? ?? ? 25? ??, ???? ??? 25??,
    ??? 25??? ??
  • delivery?? ?? ?????? ?? consumption? ??
    (extraction? ?? ??)

54
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • Oxygen Store
  • ???? ?? ?? ???? 1500ml
  • 1. oxygen remaining in the lung (FRC) important
    store (80?? ????)
  • 2. Hemoglobin? ??   ???    
  • 3. dissoluted in body-fluid       ???
  • ?? ?? oxygen content FiO2 FRC
  • FiO2 0.21       FRC  2300mL  ? 90? ? severe
    hypoxemia ??. (O2 content480ml)
  • FiO2 1          FRC  2300mL    ?  4-5? ?
    ????
  • ??? ??? induction? preoxygenation? ??? ??.

55
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • 2.Carbon Dioxide
  • Transfort 3 form
  •      1.dissolved in solution, 
  • 2. bicarbonate 
  •      3.carbamino compound??? protein
  • Dissolved Carbon Dioxide
  • ???? ? ???   0.067mL/dL/mmHg

56
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • Bicarbonate
  • ?? ?? carbonic acid? bicarbonate? ??
  •       H2O    CO2  ?  H2CO2  ?  H    HCO3-
  • On the venous side of systemic capillary
  • ???? carbonic anhydrase ? ??? CO2? ???? ???,
    ????? bicarbonate? ?? plasma? ?????
  • ??? balance? ?? chloride? plasma?? ???? ????
  • In pulmonary capillary
  • chloride ion? ???? ?? ???, ???? bicarbonate ion?
    ??? CO2? ???? alveoli?? ????
  • ?? Chloride or Hamburger shift ?? ??.
  • Carbamino Compounds
  •     R-NH2    CO2  ?  RNH-CO2-    H
  • carbamino-hemoglobin? ??? CO2? ??
  • deoxygenated hemoglobin? oxygenated hemoglobin?
    ?? 3.5??? CO2? ? ? ??

57
TRANSPORT OF RESPIRATORY GASES IN BLOOD
  • Effects of Hemoglobin Buffering on Carbon Dioxide
    Transport
  • Hemoglobin? histidine? ??? physiologic PH???
    buffer? ??
  • Hb? oxygenated state? ?? ???? ????.
  • Tissue capillary?? ???? ?? O2? ???? ??
  • CO2   H2O    HbO2 ? HbH    HCO3-    O2
  • Lung?? ??? ?? CO2? ???? ??
  • O2    HCO3-    HbH  ?  H2O    CO2    HbO2
  • Carbon Dioxide Stores
  • ?? 120L in adult
  • ?? dissolved CO2? bicarbonate ???
  • ??? ?? ?? imbalance?, 20-30? ??? ??? ???
    equilibrium? ?? 

58
CONTROL OF BREATHING
  • brain stem ? respiratory center??? rhythmic
    neural activity? ??
  • 1.Central Respiratory Center
  • Medulla?? ????, two medullary group of neuron ?
    ??.
  • 1.dorsal respiratory group inspiration ?? ???
  • 2.ventral respiratory group expiration ?? ???
  • basic rhythm
  • dorsal group??? intrinsic, spontaneous discharge
    activity ?? dorsal ventral group??
    reciprocating activity? ??
  • two pontine area? dorsal medulla? ??? ??
  • ??? respiratory rate rhythm ????
  • 1. lower pontine (apneustic) center  excitory
  • 2. upper pontine (pneumotaxic) center 
    inhibitory

59
CONTROL OF BREATHING
  • 2.Central Sensor (Chemoreceptor)
  • anterolateral surface of medulla
  • respond to CSF (H)? ??
  • effective in regulating PaCO2
  • (BBB is permeable to dissolved CO2)
  • PaCO2? ??? CSF H? ???? chemoreceptor? ??? ???,
    adjacent respiratory medullary center? ???
    alveolar ventilation(CO2 ??)? ??????? PaCO2? ???

60
CONTROL OF BREATHING
Pph. chemoRc Lung receptors
  • 3.Peripheral Sensor
  • Peripheral Chemoreceptors
  • 1. carotid bodies (at the bifurcation of the
    common carotid arteries)
  • principal peripheral chemoreceptor in human
  • PaO2, PaCO2, PH, arterial perfusion pressure? ???
    ??
  • Glossopharyngeal nerve ? ?? central respiratory
    centers ? ??????.
  • cyanide, doxapram, large dose of nicotine?? ???
  • PaO2? ???? 50mmHg??? ???? ??? ????? ???.
  • cell of the carotid body (glomus cell)
    dopaminergic neuron
  • cf) antidopaminergic drug, bilateral carotid
    surgery
  • ? hypoxia? ??  pph. ventilatory response? ????
  • 2. aortic bodies (surrounding the aortic arch)

61
CONTROL OF BREATHING
Pph. chemoRc Lung Receptor
  • Lung Receptors
  • carried centrally of vagus nerve
  • stretch receptor smooth muscle of airway? ??
  • lung? ??? ??? inspiration ?? (Herning-Breuer
    inflataion reflex)
  • lung? ???? ?? ?? exhalation? ?? ?(deflation
    reflex)
  • human? ?? minor role
  • irritant receptor( in tracheobronchial mucosa)
  • J (juxtacapillary) receptors (interstitial space
    within alveolar wall) interstitial space vol.
    ?? ?? ?? ????? ???? dyspnea? ???

62
CONTROL OF BREATHING
  • 4.Effects of Anestheisa on the Control of
    Breathing
  • Hypoventilation? ???.
  • Dual mechanism
  • central depression of the chemoreceptor
  • depression of external intercostal muscle
    activity
  • hypoventilation? ??? ????? ?? 

63
NON-RESPIRATORY FUNCTIONS OF THE LUNG
  • Filtration Reservoir Function
  • Filtration
  • acts a filter for debris
  • facilitates breakdown entrapped fibrin debris
  • Reservoir function
  • Pul. Circulation? systemic circulation? ??
    reservoir ??
  • Metabolism
  • 1.pneumocyte? surfactant?? ? ???, extrahepatic
    mixed-function oxidation? major portion? ??
  • 2.neutrophil macrophage oxygen derived free
    radical
  • 3.pulmonary endothelium metabolize a variety of
    vasoactive compound
  • 4.angiotension?? angiotensin?? ??(surface of the
    pul. endotheium)
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