Nomad : Lung Compliance & Surfactant

NOMAD: RESPIPHYSIOL: Lung Compliance NOMAD: RESPIPHYSIOL: Lung Compliance II

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LUNG COMPLIANCE & LUNG COMPLIANCE & SURFACTANTSURFACTANT

ByByDr. M. Anthony David, MD.Dr. M. Anthony David, MD.

Professor of PhysiologyProfessor of Physiology


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LUNG COMPLIANCELUNG COMPLIANCE The ‘The ‘stretchabilitystretchability’ of the lung is ’ of the lung is

called it’s Compliance.called it’s Compliance. Compliance is defined as the Compliance is defined as the

volume change per unit volume change per unit pressure change during inflation pressure change during inflation or deflation.or deflation.

Volume change : VVolume change : V22 – V – V11

Pressure Change: PPressure Change: P22 – P – P11


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Compliance = Compliance = VV22 – V – V11

PP22 – P – P11

= = ∆ V∆ V

∆ ∆ PP

LUNG COMPLIANCELUNG COMPLIANCE


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Lung ComplianceLung Compliance

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12 14 16P1 P2

V2

V1

PRESSURE

VOLUME


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LUNG COMPLIANCELUNG COMPLIANCE Compliance:Compliance:

•StaticStatic•Dynamic: considers time dimension Dynamic: considers time dimension

also.also.•Specific = Specific = Static ComplianceStatic Compliance

FRCFRC

Used for comparing lungs of Used for comparing lungs of different sizes.different sizes.


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RESISTANCERESISTANCE The oppostion to the flow of The oppostion to the flow of

air in the respiratory air in the respiratory passages is called as passages is called as Resistance.Resistance.

TYPES OF RESISTANCE:TYPES OF RESISTANCE:• AIRWAYAIRWAY• VISCOUSVISCOUS• ELASTICELASTIC


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AIRWAY RESISTANCEAIRWAY RESISTANCE The resistance air encounters The resistance air encounters

while passing through the airways.while passing through the airways. Resistance depends on the tone of

the Respiratory smooth muscle. This accounts for 20% of the

Respiratory work done.


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VISCOUS RESISTANCE The resistance offered by the The resistance offered by the

opening up of the lung tissues.opening up of the lung tissues. Accounts for 20% of the work Accounts for 20% of the work

done.done. Is caused by the opening up of Is caused by the opening up of

the tissues and the lungs to air.the tissues and the lungs to air.


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ELASTIC RESISTANCEELASTIC RESISTANCE Is offered by the elastic recoil of

the lungs during inspiration. Decreases in diseases like

Emphysema. Increases in Fibrosis. Contributes to 60% of the work

done.


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REVIEWREVIEW Lung Compliance is defined as the Lung Compliance is defined as the

volume change per unit pressure volume change per unit pressure change during inflation or deflation.change during inflation or deflation.

Lung Compliance Lung Compliance = = ∆ V∆ V

∆ ∆ PP The opposition to flow air The opposition to flow air

encounters is called as encounters is called as resistance.resistance.


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REVIEWREVIEW Types of resistance :Types of resistance :

•AirwayAirway•ViscousViscous•ElasticElastic


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WORK OF BREATHINGWORK OF BREATHING Is the work done for breathingIs the work done for breathing Basically needed to overcome Basically needed to overcome

Resistance:Resistance:•Elastic resistance: 60%Elastic resistance: 60%•Airway resistance: 20%Airway resistance: 20%•Viscous resistance: 20%Viscous resistance: 20%


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AIR DISTRIBUTION IN THE AIR DISTRIBUTION IN THE LUNGSLUNGS

The dependent parts ventilate The dependent parts ventilate well.well.

The dependent part or theThe dependent part or the base base of of the lungs has:the lungs has:•Less recoilLess recoil•Better ventilation. Better ventilation.


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APEX

BASE


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FLOW VOLUME CURVE

0

50

Lung Volume

Flow

Rat

e

TLC RV


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PRESSURE – VOLUME CURVESPRESSURE – VOLUME CURVES

Obtained by plotting different lung Obtained by plotting different lung volumes against respective trans volumes against respective trans pulmonary pressures.pulmonary pressures.

Depict the relationship between Depict the relationship between Pressure & Volume of the lung.Pressure & Volume of the lung.


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PRESSURE – VOLUME CURVESPRESSURE – VOLUME CURVES

Inflation curve: Flat- steep- flatInflation curve: Flat- steep- flat•Easiest inflation at moderate Easiest inflation at moderate

pressures.pressures. Hysteresis: Gap between the Hysteresis: Gap between the

inflation and deflation curves.inflation and deflation curves.•Cause: Surface tension of the Cause: Surface tension of the

Alveolar fluid.Alveolar fluid.•Not seen with saline.Not seen with saline.


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PULMONARY SURFACTANTPULMONARY SURFACTANT

A chemical secreted by by the type II A chemical secreted by by the type II Alveolar cells.Alveolar cells.

Composition:Composition:• Dipalmitoyl Lecithin.Dipalmitoyl Lecithin.• Phosphatidyl Glycine.Phosphatidyl Glycine.• Other Phospholipids.Other Phospholipids.• Neutral lipids.Neutral lipids.• Proteins & CarbohydratesProteins & Carbohydrates


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SURFACTANT MOLECULESURFACTANT MOLECULE


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FUNCTIONS:•Reduces the surface tension of

the thin film of alveolar fluid. This makes it easier to inflate the lungs.

• Increases the Lung Compliance.

•Prevents the Tissue fluid formation.

PULMONARY SURFACTANTPULMONARY SURFACTANT


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Surfactant: FunctionSurfactant: Function


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Surfactant: Applied AspectsSurfactant: Applied Aspects

INFANT RESPIRATORY DISTRESS SYNDROME( IRDS):•Also called Hyaline Membrane

Disease.•Can be fatal.•Seen in premature babies:

As the surfactant production has not begun in them


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Adult Respiratory Distress Syndrome(ARDS):• Primarily due to cigarette smoking.

Surfactant: Applied AspectsSurfactant: Applied Aspects


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Nomad : Lung Compliance & Surfactant

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