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Lung Function Tests. Sema Umut. Lung Factors Affecting Function. Mechanical properties Resistive elements. Mechanical Properties. Compliance Describes the stiffness of the lungs Change in volume over the change in pressure Elastic recoil

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Lung function tests

LungFunctionTests

Sema Umut


Lung factors affecting function
Lung Factors AffectingFunction

  • Mechanical properties

  • Resistive elements


Mechanical properties
Mechanical Properties

Compliance

  • Describes the stiffness of the lungs

  • Change in volume over the change in pressure

    Elastic recoil

  • The tendency of the lung to return to it’s resting state


Resistive properties
Resistive Properties

  • Determined by airway caliber

  • Affected by

    • Lung volume

    • Bronchial smooth muscles

    • Airway collapsibility


A test should be
A TEST SHOULD BE

  • Acceptabile,easy

  • Noninvasive

  • Cost effective

  • Informative

  • Reproducible


Spirometry
Spirometry

Acceptabile,easy

Noninvasive

Costeffective

Inexpensive

Informative

Reproducible


Spirometry1
Spirometry

  • It is the most commonly used lung function screening study

  • It should be the clinician's first option


When can spirometry help us?

  • - Diagnosing disease

  • - Monitoring disease

  • - Prognosis

  • Directing therapy


Indications for spirometry
Indications for Spirometry

Diagnostic

  • To evaluate symptoms, signs, or abnormal laboratory tests

    • Dyspnea

    • Wheezing

    • Cough

    • Abnormal breath sounds

    • Overinflation

    • Expiratory slowing

    • Cyanosis


Abnormal laboratory tests
Abnormallaboratorytests

  • Hypoxemia

  • Hypercapnia

  • Polycythemia

  • Abnormal chest radiographs


To screen individuals at risk of having pulmonary diseases

  • Smokers

  • Individuals in

    occupations with

    exposures to

    injurious substances


Indications for spirometry1
Indications for Spirometry diseases

  • To assess preoperative risk

  • To assess health status before physical activity programs

  • To evaluate therapy


Disability impairment evaluations
Disability diseases /ImpairmentEvaluations

  • To assess individuals for legal reasons


Prognosis diseases

Survival predictor of

general population

Copenhagen City Heart Study

13,900 subjects for 25 yrs

Lange P. J Clin Epidemiol

1990; 43: 867-873.

Cox proportional hazards

FEV1/ht2 best index

Framingham study


Spirometry Requirements diseases

1. Good equipment

2. Good technicians (efor dependent)

3. Good clinicians

- correct indication

- correct use / presentation of the data

- correct decision making


Pulmonary function testing relates
Pulmonary Function Testing relates diseases

  • Age : Smaller lung volumes as we age

  • Gender : The lung volumes of males are larger than females

  • Height

  • Race


Perform manoeuvre
Perform manoeuvre diseases

  • Attach nose clip, place mouthpiece in mouth

  • Inhale completely and rapidly

  • Exhale maximally until no more air can be expelled

  • Repeat for a minimum of 3 manoeuvres


Forced diseases VitalCapacity FVC

  • Total volume of airexpiredforcefullyafter a fullinspiration

  • Patientswithrestrictivelungdiseasehave a decreasedvitalcapacity


Slow vital capacity svc
Slow Vital Capacity (SVC) diseases

  • This is the total volume of air expired slowly after a full inspiration

  • If the SVC is greater than FVC,it indicates the presence of obstructive disease


Forced Expiratory Volume in 1 Second diseases

FEV1

Volume of air expired in the first second during maximal expiratory effort


Fev1 fvc
FEV1/FVC diseases

  • Percentage of the forced vital capacity which is expired in the first second of maximal expiration to forced vital capacity

  • In health the FEV1/FVC is usually around 80%

  • Decrease in FEV1/FVC means obstruction


Tidal volume TV diseases

The volume of air moved during normal quiet breathing (about 0.5 L)


Residuel volume rv
RESIDUEL VOLUME (RV) diseases

The volume of air remaining in the lungs after a forceful expiration (about 1.0 L).


Functional residuel capacity frc
FUNCTIONAL RESIDUEL CAPACITY(FRC diseases )

The amount of air remaining in the lungs after a normal quiet expiration


Total lung capacity tlc
TOTAL LUNG CAPACITY (TLC) diseases

It is the volume of air in the lungs when the person has taken a full inspiration

TLC = RV + VC


Tlc rv frc
TLC,RV,FRC diseases

Can not be measured by spirometry

  • Helium dilution

  • Nitrogenmetry

  • Body plethysmography


INTERPRETATION OF SPIROMETRY diseases

  • Compare the measured values of the patient with normal values derived from population studies

  • The percent predicted normalis used to define normal and abnormal and to grade the severity of the abnormality


Categories of disease
Categories of Disease diseases

  • Obstructive

  • Restrictive

  • Mixed


Spirogram diseases measurestwocomponents - airflowandvolume

Ifflow is reduced, thedefect is obstructive

Ifvolume is reducedthedefect is restrictive


Interpretation
Interpretation diseases

FVC and FEV1 are normal – NORMAL

FVC is low but FEV1/FVC is >80 RESTRICTIVE

FEV1/FVC < 70% OBSTRUCTIVE


Spirometry2
Spirometry diseases

  • Obstruction (FEVı /FVC) < %70


Obstructive lung diseases
Obstructive Lung Diseases diseases

  • Asthma

  • Chronicobstructivepulmonarydisease


COPD diseases

-COPDis characterized by airflow limitation that is not fully reversible

-The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gases


Diagnosis of COPD diseases

EXPOSURE TO RISK

FACTORS

SYMPTOMS

cough

tobacco

sputum

occupation

shortness of breath

indoor/outdoor pollution

è

è

è

SPIROMETRY


Asthma
Asthma diseases

  • Asthma is a chronic inflammatory disease of the airways

  • Inflammation causes the airways to narrow periodically

  • Thisproduces wheezing and breathlessness

  • Obstruction to air flow is reversible


Bronchodilator Test diseases

  • Evaluates how responsive the patient is to a bronchodilator medication

  • Spirometry is repeated about 15 minutes after giving a bronchodilator (400 mg salbutamol)


Why test for reversibility
WHY TEST FOR REVERSIBILITY? diseases

  • To determine best function

  • To follow rate of change in PFTs over time

  • To exclude asthma

  • To determine response to therapy


Reversibility
REVERSIBILITY diseases

Increase of 200 ml or 12-15% of the baseline FEV1 shows

REVERSIBLE

OBSTRUCTION

40

Both drugs combined

30

20

10

0

0

2

4

6

8


Restriction
Restriction diseases

  • Restriction means a decrease in lung volumes


Extrinsic restrictive lung disorders
Extrinsic Restrictive Lung Disorders diseases

. Neuromuscular Disorders

. Scoliosis, Kyphosis

. Rib fractures

. Pleural Effusion

. Pregnancy

. Gross Obesity

. Tumors

. Ascites


Intrinsic restrictive lung disorders
Intrinsic Restrictive Lung Disorders diseases

  • Pnuemonectomy

  • Pneumonia

  • Lung tumors

  • Interstitial lung diseases

  • Sarcoidosis

  • Lung oedema


Flow – Volume Loop diseases

is a measure of how much air can be inspired and expired from the lungs

It is a flow rate measurement


Restrictive lung disease
Restrictive Lung Disease diseases

  • Characterized by diminished lung volume

  • Decreased TLC, FVC

  • Normal FEV1/FVC ratio


Large airway obstruction can be detected by flow volume loop
Large Airway Obstruction diseases can be detected by Flow – Volume Loop

  • Characterized by a truncated inspiratory or expiratory loop


Extra thoracic upper airway obstruction
Extra-thoracic diseases Upper Airway Obstruction


Peak Expiratory Flow Rate PEFR diseases

  • The maximum flow rate during the forced vital capacity maneuver

  • Useful to monitor asthma


Measuring pef
Measuring PEF diseases

PEF must be achieved as rapidly as possible and at a high lung volume as possible

The subject must be encouraged to blow as vigorously as possible


When is pef useful
When diseases is PEF useful?

PEF can be very useful in diagnosing occupational asthma


Arterial blood gases indication
ARTERIAL BLOOD GASES diseases INDICATION

  • Oxygenation

  • Ventilation

  • Acid-Base Status


Arterial blood gases
ARTERIAL BLOOD GASES diseases

  • Blood gases is a measurement of how much oxygen and carbon dioxide is in the blood

  • Determines the acidity (pH) of the blood


Arterial blood gases1
ARTERIAL BLOOD GASES diseases

  • Blood is taken from an artery

  • The blood may be collected from the radial artery, the femoral artery , or the brachial artery


Arterial blood gases2
ARTERIAL BLOOD GASES diseases

  • After the blood is taken, pressure is applied to the site for a few minutes to stop the bleeding

  • The sample must be quickly sent to a laboratory


Blood gas report
Blood Gas Report diseases

  • pH 7.4

  • PaCO2 (mm Hg) 40

  • PaO2 (mm Hg) 110 - 0.5(age)

  • HCO3- (mmol/L) 24

  • B.E. (mmol/L)0

  • O2 saturation >90%


Causes of a low pao 2
Causes of a low PaO diseases 2

  • V/Q mismatch

  • Dead space ventilation

  • Shunt

  • Diffusion Impairment

  • Alveolar Hypoventilation

  • Altitude


Alveolar hypoventilation
Alveolar Hypoventilation diseases

  • Reduced Respiratory Drive

  • Pump failure


Analysis of ventilaton
ANALYSIS OF VENTILATON diseases

  • Hypercapnea > 45 mm Hg Hypoventilation

  • Respiratory Acidosis

  • Hypocapnea < 35 mm Hg Hyperventilation

  • Respiratory Alkalosis


Respiratory alkalosis
Respiratory alkalosis diseases

  • Low levels of carbon dioxide in the blood due to alveolar hypervetilation (breathing excessively)


Respiratory acidosis
Respiratory acidosis diseases

  • The kidneys and lungs maintain the body's acid/base (pH) balance

  • Respiratory acidosis develops when carbon dioxide is elevated

  • Primarily caused by alveoler hypoventilation ( decreased breathing)


Pitfalls
Pitfalls diseases

  • Venous Sample

    _PaO2 = 40, PaCO2 = 45

    • Free flow into syringe

  • Air-bubble in syringe

    • Falsely elevated PaO2

  • Arterial blood sample should be transported on ice under anaerobic conditions


Spirometry is essential in respiratory evaluation as tension arterial measurement is essential in cardiovascular evaluation


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