trachea (generation #1) primary bronchi (generation #2) conducting airways generations 1-16 2 o...

Trachea(Generation #1)

Primary Bronchi (Generation #2)

Conducting Airways Generations 1-16

2o Bronchi (Generation #3)

Respiratory ZoneGenerations ~17-23

Alveoli

Respiratory Bronchioles

PAPa Pv

Zone 1PA>Pa>Pv

Low Flow

PA

Pa Pv

PA

Pa Pv

Zone 2Pa>PA>Pv

Waterfall

Zone 3Pa>Pv>PA

Hi Flow

O2

CO2

venous arterial

PB=0

PA<0

Flow=P/R

O2

CO2

venous arterial

PB=0

PA<0

O2

CO2

venous arterial

PB=0

PA>0

Atmospheric AirHigh O2 (150 mmHg)

CO2 ~ 0

Alveolar AirO2 ~100 mmHgCO2 ~ 40 mmHg

Inspiration Expiration

Fick’s lawJ = DA (C/ X)

Lung

Chest Wall

StuckTogether

Lung

Air leakPneumothoraxLung collapses& Chest expands

Hemoglobin-O2 Binding Curve

0 20 40 60 80 1000

20

40

60

80

100

0

5

10

15

20

Venous

Arterial

CO2

PaO2 (mm Hg)

% H

b S

atu

rati

on

Hb

O2 co

nten

t (ml O

2 /dl)

VT

To

t al L

un g

Ca

pac i

ty

Expiratory Reserve

InspiratoryReserve

FRC

InspiratoryCapacity

Residual Volume

VitalCapacity

Expiratory Reserve

Residual Volume

VitalCapacity

VT

To

t al L

un g

Ca

pac i

ty

InspiratoryReserve

FRC

InspiratoryCapacity

TLC

RV RV

IC

VT

IR

FRCER

VC

VL

V1

VL

V1

C1V1=N C2(V1 +VL) =N

VL=(C1/C2)V1 –V1

Equilibrate Concentration

C1V1= C2(V1 +VL)

III. A Few Terms (for Your Convenience) Eupnia - Normal breathing. Apnea - cessation of respiration (at FRC). Apneusis - cessation of respiration (in the inspiratory phase). Apneustic breathing – Apneusis interrupted by by periodic exhalation. Hyperpnea – increased breathing (usual VT). Tachypnea – increased frequency of respiration. Hyperventilation – increased alveolar ventilation (PACO2 <37 mm Hg). Hypoventilation – decreased alveolar ventilation (PACO2 >43 mm Hg). Atelectasis – closed off alveoli, typically at end exhalation. Cheyne-Stokes Respiration – Cycles of gradually increasing and decreasing VT. Dyspnea- Feeling of difficulty in breathing. Orthopnea- Discomfort in breathing unless standing or sitting upright. Ppl - Pleural pressure (pressure in space between visceral and parietal plurae) PTP - Transpulmonary pressure (distending pressure of airway) PACO2 - Alveolar PCO2 (partial pressure of CO2). PaCO2 - arterial PCO2. PvCO2 - venous PCO2 PAO2 - Alveolar PO2 PaO2 - arterial PO2 PvO2 - venous PO2 PECO2 - PCO2 of exhaled air FECO2 – fraction of exhaled air which is CO2 (i.e. A= Alveolar, a= arterial, v= venous, E = exhaled, I = inspired)

VE – Expired volume (liters) . VE – ventilation (liters/min) . VA – Alveolar ventilation (liters/min)

Q – Blood Flow (liters/min)

Some Normal Values For Some Key Pulmonary Parameters FRC 2.5 0.5 L RV 1.2 0.3 L TLC 6.5 0.5 L VT 500 100 ml FVC 4.5 0.5 L FEV1.0 / FVC >75% Frequency 10-12/min V

A (norm) 5 0.5 L/min V

E (norm) 7 0.7 L/min V

E (max) 120-150 L/min Max. insp flow 7-10 L/sec

Max. exp flow 6-9 L/sec Compliance 60-100 mL/cm H20 PAO2 100 mm Hg PaO2 (21% O2) 90-95 mm Hg PaO2 (100% O2) >500 mm Hg PaCO2 40 3 mm Hg Arterial pH 7.37-7.43 PvO2 40 mm Hg PvCO2 46 mm Hg [Hb] 14-15 g/dL

Expiratory Reserve

Residual Volume

VitalCapacity

VT

To

t al L

un g

Ca

pac i

ty

InspiratoryReserve

FRC

InspiratoryCapacity

600 ml

2.5 L

1.2 L

5 L

~6

.5 L

Lung

Chest Wall

StuckTogether

Lung

As we remove airfrom pleural spacethe lung expands& the chest wallgets pulled in.

ChestWall

RecoilForce

Lung Wall

RecoilForce

Ppl = 0

Ppl = -2

Normal Emphysema lung recoil

Fibrosis lung recoil

Pneumo- thorax

Ppl= -8

Balance of Forces Determines FRCHooke’s Law: F = -kx

Intrapleuralspace

Incr

easi

ng

volu

me

Dec

reas

ing

vo

lum

e

Normal FRC

Ppl = -5

P1

P2

For same T, P1>P2

(I.e. 2T/r1 > 2T/r2)

LaPlace2T=PrP=2T/r

Sur

face

Are

a (r

elat

ive)

Surface Tension (dynes/cm)30 60

WaterDetergent

LungSurfactant Plasma

80

Surface Area Surface Tension

Surfactant40% Dipalmitoyl Lecithin25% Unsaturated Lecithins 8% Cholesterol27% Apoproteins, other phospholipids, glycerides, fatty acids

Sur

face

Are

a (r

elat

ive)

Surface Tension (dynes/cm)30 60

WaterDetergent

LungSurfactant

80

Surface Area Surface Tension

1. Reduces Work of Breathing2. Increases Alveolar Stability

(different sizes coexist)3. Keeps Alveoli Dry

Static Compliance Curves

-18-16-14-12-10-8-6-4-202

Normal

VT

FRCN

Pleural Pressure, Ppl (cm H2O)

Lu

ng

Vo

lum

e

Expiration

Inspiration


-18-16-14-12-10-8-6-4-202

Fibrosis(low compliance)

Normal

Emphysema(high compliance)

VT

FRCNVT

FRCF

VT

FRCE


Lu

ng

Vo

lum

e

ChestWall

RecoilForce

Lung Wall

RecoilForce

Normal FRC

Ppl = -5

Normal

Balance of Forces Determines FRCHooke’s Law: F = -kx

Intrapleuralspace

Incr

easi

ng

vol

ume

Dec

reas

ing

v

olum

e

Ppl = 0

Ppl = -2

Emphysema lung recoil

Fibrosis lung recoil

Pneumo- thorax

Ppl= -8

Lung has weight

-8

Ppl = -2

-5

Apex

Base

Chest Wall

Regional- Apex to Base Differences

-14-12-10-8-6-4-202

Apex

Base

Norm Lung Volume

Alveolar VolumeAlve Ventilation

Apex Base

++ ++

Inspiration

Inspiration


Lu

ng

Vo

lum

e

Regional- Apex to Base Differences

-14-12-10-8-6-4-202

ApexV

Base


Lu

ng

Vo

lum

eLow Lung Volume(shifts to lower V)

Alveolar VolumeAlve Ventilation

Apex Base

++++

Apex to Base Differences

-14-12-10-8-6-4-202

ApexV

Base


Lu

ng

Vo

lum

e

Low Lung V

Normal Lung V

PA (cm H2O)+1

-1

0

+0.5

-0.5

0

Air Flow (L/s)

1 2 3 4

time (sec)

-5

-8

Ppl (cm H2O)

The linear Dashed trace is the Ppl required to overcome recoil forces.More Ppl (solid curve) is required toovercome airway resistance to flow.N.B. P = PA-PB Resist•Flow.

VT (L)0.4

0

0.2

Respiratory Cycle


-5

-8

-8

-6

-5

Rest FRC

Inspiration

End Inspiration

+

0

0

- AirFlow

PA= 0

Ppl

End Expi-ration-FRC

Expiration

time

Respiratory CycleSingle VT Breath

PB=0


-18-16-14-12-10-8-6-4-202

Normal

VT

FRCN


Lu

ng

Vo

lum

e

Expiration

Inspiration

PA (cm H2O)+1

-1

0

+0.5

-0.5

0

Air Flow (L/s)

1 2 3 4

time (sec)

-5

-8

Ppl (cm H2O)

Case of ZERO Resistance

VT (L)0.4

0

0.2

Respiratory Cycle


-5

-8

-8

-6

-5

Rest FRC

Inspiration

End Inspiration

+

0

0

- AirFlow

PA= 0

Ppl

End Expi-ration-FRC

Expiration

time


PB=0

PA (cm H2O)+1

-1

0

+0.5

-0.5

0

Air Flow (L/s)

1 2 3 4

time (sec)

-5

-8

Ppl (cm H2O)

The linear Dashed trace is the Ppl required to overcome recoil forces.More Ppl (solid curve) is required toovercome airway resistance to flow.N.B. P = PA-PB Resist•Flow.

VT (L)0.4

0

0.2

Respiratory Cycle


-5

-8

-8

-6

-5

Rest FRC

Inspiration

End Inspiration

+

0

0

- AirFlow

PA= 0

Ppl

End Expi-ration-FRC

Expiration

time


PB=0

PA (cm H2O)+1

-1

0

+0.5

-0.5

0

Air Flow (L/s)

1 2 3 4

time (sec)

-5

-8

Ppl (cm H2O)

VT (L)0.4

0

0.2

Respiratory Cycle


-5

-8

-8

-6

-5

Rest FRC

Inspiration

End Inspiration

+

0

0

- AirFlow

PA= 0

Ppl

End Expi-ration-FRC

Expiration

time


PB=0

Case of HIGH Resistance

Mild Expiratory Effort (P+13)

0

Normal at FRC-5

0

Dynamic Compression of Airways

PTP=+5PPl - PA= -5

Strong Expiratory Effort (P+30)

+25

30 25 20 15 10 5 0

EPP

Normal

+28

30 25 20 15 10 5 0

EPP

Emphysema

in unsupported airways

13 10 8 6 4 2 0

EPP

Emphysema+11

PPl-PA=-2

-2

0

Dynamic Compression of Airways

EPPEqual Pressure Point(in supported airways)

+13

Mild Expiratory Effort (P+13)

+8

8 4 0

Normal at FRC-5

0

+13

+13

PTP=+5PPl - PA= -5

Low VL&Basal Alv

also like this

Airway Generation 5 1 0 15

Tot

al C

ross

Sec

tiona

l Are

a

ConductingZone

RespZone

v = Flow/A

NR= Dv/ =density D= diameter v= velocity = viscosity

Airway Generation

Res

ista

nce

Subsegmental Bronchi

5 1 0 15

Resistance

8lR= ——— r4

k•numberR= ————— A2

Lung Volume

Air

wa

y R

es

ista

nc

e

Normal

RecoilEmphysema

Fibrosis

Normal

ResistanceObstructive

RecoilRestrictive

time (sec)

Vol

ume

FRC

Inspiration

Forced Vital Capacity

TLC

FEV1.0 FVC

1 sec

FEV1.0 = 4 LFVC = 5 L % = 80%

RV

NormalTLC

FEV1.0

FVC

1 sec

FEV1.0 = 1.2 LFVC = 3.0 L % = 40%

RV

Obstructiveairway resist

Restrictivelung recoil

TLCFEV1.0

FVC

1 sec

FEV1.0 = 2.7 LFVC = 3.0 L % = 90%

RV

Effort Independent limb in forced expiration.

TLC RV

Exp

irato

ry F

low

Lung Volume

Flow-Volume Curves

Due to Dynamic Airway Compression and airway collapse.

Inverted Inspiration

RV

Exp

irato

ry F

low Forced expiration

Inspiration

Insp

irato

ry F

low

TLC Lung Volume

Normal

Obstructive

Restrictive

9 8 7 6 5 4 3 2 1 Lung Volume (L)

Flo

w R

ate

(L/s

ec)

9

TLC RV

Lung Volume (L)

6 5 4 3 2 1

3. Alveolar Plateau

1. 2. Dead Space Washout

4.

N2 C

once

ntra

tion

(%)

20

40

Critical Closing Volume Test

ClosingVolume

Apex to Base Differences

-14-12-10-8-6-4-202

ApexV

Base


Lu

ng

Vo

lum

e

Low Lung V

Normal Lung V

TLC RV

Lung Volume (L)

6 5 4 3 2 1

3. Alveolar Plateau

1. 2. Dead Space Washout

4.

N2 C

once

ntra

tion

(%)

20

40

Critical Closing Volume Test

ClosingVolume

IncreasedClosingVolume

PO2=100 mm Hg 21 ml O2/dL

PO2=100 mm Hg 0.3 ml O2/dL

O2

O2

PO2=100 mm Hg 21 ml O2/dL

PO2=100 mm Hg0.3 ml O2/dL dissolved20 ml O2/dL HB-O2

O2

O2

Expired Lung Volume (L)

0 0.2 0. 4 0.6 0.8

Alveolar Plateau

Inspired O2 dilutedby alveolar N2

N2 C

once

ntra

tion

(%)

20

40

A

B

Fowler’s Test Area A = Area B

Vd

The Bohr Equation

VD1 (PACO2 – PECO2) = VT PACO2

VD2 (PaCO2 – PECO2) = VT PaCO2

D. Sample Calculation VT = 600 ml PACO2 = 38 mmHg

PECO2 = 28 mmHg PaCO2 = 40 mmHg

VD1 = 600(38 – 28)/38 = 158 ml

VD2 = 600(40 – 28)/40 = 180 ml

E.Alveolar Ventilation . . . VE = VD + VA = VT frequency. . . VA = VE - VD

.1.For VT = 500 ml, f = 10/min, VD = 150 ml, what is VA?

.VA = 5000 - 1500= 3500 ml/min . .2.If VE is doubled by increasing VT what is VA? = 10,000 - 1500= 8500 ml/min . .3.If the same VE is obtained by doubling frequency, what is VA? = 10,000 - 3000= 7000 ml/min .Thus increasing VT rather than frequency is more effective for VE.

F. Alveolar Ventilation and CO2 production . VCO2 = Expired CO2 - Inspired CO2

.=VA FACO2

. VA x PACO2

= PA

.

.VCO2 K VA =

PACO2XIII. RESPIRATORY EXCHANGE RATIO . . RQ = VCO2/VO2 The relative amounts of O2 consumed and CO2 produced depends upon the fuel. Carbohydrate RQ = 1 Fat RQ = 0.7 Protein RQ = 0.8 A typical "normal" RQ is 0.8 The partial pressures of O2 and CO2 are also affected.

PACO2 40 RQ = = PIO2 - PEO2 50

Study Questions/ Exercises

Q: Why does this ratio necessarily reflect the RQ? Alveolar Gas Equation – Allows you to estimate PAO2 – PaO2 gradient. PAO2 = FIO2 (PATM – PH2O) – PaCO2/RQ + K = PIO2 – PaCO2/RQ K = PACO2 FIO2 ({1-RQ}/RQ) a small correction (2 mm Hg) usually ignored

XIV. RESPIRATORY GAS CASCADEPO2 PCO2

mm Hg mm Hg

Air (dry) 760 0.21 160 0Trachea (humidified; 760-47) 713 0.21 150 0Alveolus (some O2 absorbed by blood) 100 40

Arterial (R-L Shunt) 90 40+Mixed venous (O2 absorbed by tissues) 40 46

time in Capillary (sec)

0.25 0.5 0.75

PO

2 m

m H

g

20

40

60

80

100

NormalTransit TimeExercise

ShortensTransit

time

Thickened Alveolar

Membrane

O2 Diffusion in Pulmonary Capillaries(transit time)

Hemoglobin-O2 Binding Curve

0 20 40 60 80 1000

20

40

60

80

100

0

5

10

15

20

26

50

75

9097.5

PaO2 (mm Hg)

% S

atu

rati

on

of

Hem

og

lob

inH

b-O

2 con

tent

(ml O

2 /100 ml b

loo

d)

Bohr Shift Hb-02 Curve

0 20 40 60 80 1000

20

40

60

80

100

Normal Hb

Bohr Shift H+], CO2, Temp or DPG

H+], CO2

Temp

PaO2 (mm Hg)

% S

atu

rati

on

of

Hem

og

lob

in

0 20 40 60 80 1000

5

10

15

20

Myoglobin

Normal Hb

Anemia

Carbon Monoxide

PaO2 (mm Hg)

Hb

-O2 c

on

ten

t(m

l O2 /

100

ml b

loo

d)

Capillary Wall

CO2 + H2O — H2CO3 H+ + HCO3-

O2CO2

CO2Cl-

H+ + HbO2 HHb + O2

CarbaminoHHb-CO2

O2

TissueCO2 Loading & O2 Unloading

c.a.

Alveolar Wall

O2CO2

CO2

Cl-

H+ + HbO2 HHb + O2

CarbaminoHHb-CO2

O2

LungsCO2 Unloading & O2 Loading

c.a.

HCO3-

CO2 + H2O — H2CO3 H+ + HCO3-

O2 helps CO2 unloading

Arterial (O2)

Exercise Venous

37 40 43 46 49 52

46

48

50

52

54

Rest Venous

PCO2 (mm Hg)

CO

2 C

on

ten

t(m

l CO

2/1

00

ml b

loo

d)

HALDANE SHIFT

PO2 = 40PCO2 = 45

Normal VA/QLow VA/Q High VA/Q

CO2 = 45

PO2 = 150PCO2 = 0

PO2 = 100PCO2 = 40

PO2 = 150PCO2 = 0

. . .

Ventilation Perfusion Ratios

No flow

PO2 = 40PCO2 = 45

Low VA/Q.

Normal VA/Q.

PO2 = 100PCO2 = 40

High VA/Q.

PO2 = 150PCO2 = 0

PO2 (mm Hg)

PC

O2 (

mm

Hg)

50 100 150

50

Base

Apex

Flo

w o

f B

loo

d o

r A

irV

A /Q

Ratio

Bottom TopDistance up Lung

Ventilation

Perfusion

VA/Q

1

2

3

.

.

Region VA VA Q VA/Q PCO2 PO2 Apex + + + Base + ++ +

. .

Mechanisms of Hypoxemia

PaO2 PaCO2 PO2 (A-a) PaO2 with 100% O2 Hypoventilation low High Norm >550

Diffusion low norm-low high >550

R-L Shunt low norm-low high <550 . VA/Q Imbalance low norm-lo-hi high >550

Other Hypoxemias (without low PaO2)a. Anemiab. Carbon Monoxidec. Hypoperfusion (CV problem)

Local Controla. Low PAO2 vasoconstrictionb. Low PVCO2 bronchoconstriction

FourthVentricle

Nucleusretroambiguous(ventral)

NucleustractusSolitarius(dorsal)

C1

MedullaOblongata

CCut-off

Bvent

AInsp

Dors ts

PneumotaxicCenter

Apneustic Center

–

Periph &CentralChemo-receptors

+

RespiratoryMuscles

+

+

VagusStretch

+

Ton

ic In

sp D

rive

+Cut-offsignal

thresh

Arterial PO2 (mm Hg)

% m

axim

al f

iring

rat

e

50 100 500

50

75

25

Peripheral Chemoreceptor Responsiveness

BBB CSFPlasma

CO2

HCO3

+

H+

CO2 HCO3 + H+

Pumped

RespiratoryAcidosis (PaCO2)

CNS Acidosis then HCO3 is pumped in(& restores pHCNS faster than kidneys can restore pHsystemic)

BBB CSFPlasma

CO2

HCO3

+

H+

CO2 HCO3 + H+

Metabolic Acidosis

Hyperventilation& PaCO2

CNSAlkalosis !!!!

(then pump HCO3 out)

30 60 900

10

20

30

40

50

60

PCO2 = 40 mm Hg

PCO2 = 45 mm Hg

PCO2 = 20 mm Hg

PaO2 (mm Hg)

Ven

tilat

ion

(L/m

in)

Ventilatory Response to O2

35 40 45 50 550

20

40

60

PaO2 200 mm Hg

PaCO2 (mm Hg)

Ven

tilat

ion

(L/m

in)

PaO2 ~100 mm Hg

PaO2 ~ 60 mm Hg

Ventilatory Response to CO2

35 40 45 50 550

10

20

30

40

50

NormalMetabolic Alkalosis

Metabolic Acidosis

PaCO2 (mm Hg)

Ven

tilat

ion

(L/m

in)

Ventilatory Response to CO2

EFFECTS OF HIGH ALTITUDE A. At 10,000 ft PB=525 mmHg inspired PO2 is ~100 mmHg PAO2 is ~50 mmHg. At 15,000 ft PB=380 mmHg inspired PO2 is ~70 mmHg PAO2 is ~20 mmHg. At Mt Everest PB=250 mmHg, inspired PO2 is ~42 mmHg PAO2 is ~0 mmHg. At 63,000 ft PB=47 mmHg, inspired PO2 is ~0 mmHg tissues boils, H2O vapor. B. Acclimatization and hyperventilation at 10,000 ft Time at High Alt. PaO2 PaCO2 pH blood pH CSF VE [HCO3]

1 Hr low low high high - Hypoxic drive is restrained by low PaCO2 and high pH. 1-2 day. low low high Norm. - CSF chemoreceptors no longer limiting hyperventilation. 2-4 days low low Norm. Norm. Peripheral alkalosis no longer restraining hyperventilation. 30 Yrs. low Norm. Norm. Norm. - - Hypoxic response of chemoreceptors lost.

BBB CSFPlasma

CO2

HCO3

+

H+

CO2 HCO3 + H+

RespiratoryAlkalosis

high pHCSF limits Hyperventilation

When pHCNS

returns to norm (HCO3 pumped out)VE is less restrained