Lung Function Tests

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					Respiratory Measurement I

LUNG FUNCTION TESTS
PY3002

Dr P. KIPPELEN

LECTURE OUTLINE
• • • • Tests of ventilatory capacity Lung volumes Gas exchange Exercise tests

• Bronchial provocation tests • IOC rules for asthma testing in athletes

FORCED EXPIRATION TEST
• • • • Simplest test One of the most informative Requires minimal equipment Trivial calculations

• Majority of patients with lung disease: abnormal forced expiration

THE SPIROMETER
• Old version
– spirometer bell – kymograph pen

• New version
– portable

RESPIRATORY MANOEUVRE

 Maximal
breath in

 

 Maximal
breath out

FEV1 & FVC
• Forced expiratory volume in 1 second
– 4.0 L FEV1 FVC

• Forced vital capacity
– 5.0 L – usually less than during a slower exhalation

• FEV1/FVC = 80%

FLOW-VOLUME CURVE
in HEALTHY subjects
(in L/sec)

(in L)

FVC

FLOW-VOLUME CURVE
in respiratory patients • Restrictive disease
–  expansion of
the lung – e.g., interstitial fibrosis

• Obstructive disease
 FEV1  FVC

–  resistance to airflow – e.g., COPD, asthma

BRONCHIAL PROVOCATION TESTS
• Exposure of the airways to a stimulus
– allergen – exercise – pharmacological bronchoconstrictive agent

• Response of the smooth muscle ?
– baseline FEV1 – post-exposure FEV1

 Airway hyperresponsiveness

EXERCICE TESTING
5

4

Normal subject

FEV1 in Litres

3

Drop in FEV1  10% = positive test
Asthmatic patient

2

Exercise
1 0 8

Spirometry
14

20

Time in Minutes

LUNG VOLUMES

• Values obtained by simple spirometry
• For the others parameters additional measurements needed

LUNG VOLUMES
Residual Volume Tidal volume
Expiratory reserve volume

Dead space

Total lung capacity

Vital capacity

Tidal volume

Inspiratory reserve volume

FUNCTIONAL RESIDUAL CAPACITY
• Measured by
– body plethysmography – helium dilution

• Body plethysmography
– mouthpiece obstructed – rapid panting

 during inspiration  pressure of the air in the lungs  air in the box expands slightly   pressure in the box

By applying Boyle’s law (P · V = constant)  lung volume obtained

FUNCTIONAL RESIDUAL CAPACITY
At beginning After several minutes

• Helium dilution • Spirometer of known volume
and helium concentration connected to the patient
• Closed circuit • Law of conservation of mass

[He] initial · Vs = [He] final · (Vs + VL)
 Unknown lung volume can be calculated

RESIDUAL VOLUME

RV = FRC - ERV

INTERPRETATION of RESULTS
• In patients with obstructive diseases
– airway closure occurs at an abnormally high lung volume

  FRC (functional residual capacity)   RV (residual volume)

• Patients with reduced lung compliance (e.g., diffuse
interstitial fibrosis)
– stiffness of the lungs + recoil of the lungs to a smaller resting volume

  FRC   RV

GAS EXHANGE
 Blood gases
= most important measurement in the management of respiratory failure – puncture of the radial artery or
– indwelling radial artery catheter

• PaO2 – normal value = 95 mmHg (85-100) –  with age (85 mmHg at 60)
–  VA/Q inequality

– Hypoxemia:  in PaO2

CAUSES OF HYPOXEMIA
• Hypoventilation
–  alveolar ventilation
Diffusion impairment

• Diffusion impairment
–  blood-gas barrier thickening –  contact time

O2

• Shunt
• VA/Q inequality
+ residence at high altitude
Shunt

BLOOD GASES
• PaCO2
– normal values : 37-43 mmHg – almost unaffected by age

• Cause of  PaCO2
– hypoventilation – VA/Q inequality
–  blood-gas barrier thickening –  contact time

• pH
– acidosis
– respiratory acidosis / metabolic acidosis

– alkalosis
– respiratory alkalosis / metabolic alkalosis

GAS EXHANGE
 Diffusing capacity
– of the lungs to CO – manoeuvre:
– vital capacity breath of 0.3% CO + 10% helium – breath holding for 10 sec – full exhalation

• Why CO ?
– CO taken up by the blood along the capillary – uptake of CO determined by
– diffusion properties of the blood-gas barrier (thickness & area)
– rate of combination of CO with blood  number cells in capillaries

EXERCISE TESTS
• Why exercise ?
– at rest, the normal lung has enormous reserves of function – during exercise,  reserves
 exercise can reveal minor dysfunctions – to assess disability

• Common variables
– – – – – work load total ventilation respiratory frequency tidal volume HR
– – – – ECG blood pressure VO2, VCO2 arterial PO2, PCO2 and pH

DYSPNEA
• Sensation of difficulty with breathing • Demand of ventilation out of proportion to the patient’s ability to respond to that demand • Inability to adjust CO2 and pH • Common in - unfit people
- elderly people - respiratory patients

• But assessment difficult

Respiratory Measurement II

HOW TO DETECT ASTHMA IN ATHLETES ?
PY3002

Dr P. KIPPELEN

APPENDIX A OF THE OLYMPIC ANTI-DOPING CODE
The List of Prohibited Substances and Prohibited Methods dated 1st January 2003 states that: Formoterol, Salbutamol, Salmeterol, Terbutaline

are: “Permitted by inhaler only to prevent and/or treat asthma and exercise-induced asthma.”

2001 IOC WORKSHOP
• Recent Olympics:  in the number of athletes notifying the need to inhaled a beta2-agonist (IBAs)

Games Los Angeles Atlanta Nagano Sydney

IBAs 119 383 128 607

Athletes 6802 10677 2296 11087

Percent 1.7% 3.6% 5.6% 5.5%

NB: At Seoul and Barcelona notification unnecessary. Notifications from Montreal unavailable

2001 IOC WORKSHOP
• High prevalence of misdiagnosed asthma/EIB in the athletic population (Rundell et al., 2001) • No scientific evidence to confirm that IBAs  performance
– at pharmacological doses! – beta2-agonists, when administered systemically, do have anabolic effects

• Skewed distribution of notifications of IBAs by sport with a higher prevalence in endurance sports

2001 IOC WORKSHOP
• MEDICATION - Under-use of inhaled corticosteroids - Daily use of IBAs may result in tolerance and increased airway reactivity
(Inman et al., 1996; Hancox et al., 1999,2002)

Hancox et al., AJRCCM, 2002

MAJOR OUTCOME
• Since Salt Lake City (2002): athletes have to prove they have got asthma/EIB to be allowed to take IBAs • Which pulmonary function tests can be used ?
– baseline spirometry: but (supra)normal values usually registered in elite athletes – response to IBAs: +12% FEV1 from baseline = proof of airway narrowing

– bronchial provocation tests

BRONCHIAL PROVOCATION TESTS
• Objective to detect airway hyperresponsiveness (AHR)

• Direct stimuli
– methacholine – histamine  only ONE mediator

• Indirect stimuli
– exercise – hypertonic saline – eucapnic voluntary hyperventilation  a lot of mediators released

METHACHOLINE
• Inhalation of increasing doses of a pharmacological agent • Response of the smooth muscle • Dose or concentration that induce a 20% drop in FEV1
• Principal limits:
Cumulative % of subjects 80 70 60 50 40 30 20
Athletes

Controls

– Non specific for the diagnosis of asthma
(Langdeau et al. 1999)

– Do not exclude EIB

10
0

<2

<8

<16

16

PC20 Methacholine (mg/ml)

EXERCISE TESTING
• Methods
– – – – High intensity exercise 6-8min duration Post-exercise spirometry (3, 5, 7, 10 & 15min) If FEV1 drop  10% : consistent with EIB

• In the lab:

– Choice limited to 2 or 3 ergometers – Neutral air conditions

 False negative tests (Rundell et al. 2000) • In the field:
– Recommended – But not always feasible

 Need surrogate challenges

HYPERTONIC SALINE
• Hypothesis:
– Changes in the osmolarity of the airways  Cells shrinks  Release of inflammatory mediators  Airway narrowing

• Methods:
– – – –

exposure to a saline solution time progressively increased FEV1 recorded 1 min after each exposure If FEV1 fall  15% = consistent with asthma

 Very messy

EUCAPNIC VOLUNTARY HYPERVENTILATION
• 6min of hyperpnoea
% Fall in FEV1

– dry air – 4.9% CO2

50

40 30
20

• 10% fall in FEV1 • Specific for diagnosis of EIA
(Rundell et al. 2004)

10 0
n = 22

• Recommended by the IOC

6 min EVH

6 min Exercise

IBAs USE SYDNEY vs ATHENS
SYDNEY 2000
(notified)

ATHENS 2004
(approved)

• NOC

IBAs

PERCENT

IBAs

PERCENT

• • • • • •

NZL AUS UK USA CAN FIN

31 128 62 112 55 10

21.1% 20.7% 19.9% 18.9% 18.6% 14.3%

11 65 62 50 11 4

11.3% 13.7% 23.3% 9.1% 4.1% 6.6%

Anderson et al. submitted

ASTHMA IN TEAM GB
Dickinson et al., 2005

CONSEQUENCES OF THE NEW RULE
• Dickinson et al., Thorax, 2005 –  false positive diagnosis
• 21% of athletes with a previous diagnosis of asthma have failed to the demonstrate evidence of asthma

–  false negative diagnosis
• 10% of athletes with no history or previous diagnosis of asthma were tested positive

 Only athletes who need the medication get it!

ASTHMA & MEDALS IN ATHENS
• 56 athletes met the criteria to use asthma medication. They won: - 7 Gold - 7 Silver - 3 Bronze medals
• 13 athletes failed to meet the IOC criteria and were subsequently removed from asthma medication won: - 2 Gold medals

 Asthma and sport not incompatible !!!

KEY POINTS
• Since Salt Lake City, compulsory for Olympic athletes to prove they have got asthma to use IBAs
 approval given by a scientific independent panel of the IOCMC

• Recommended tests for the diagnosis of asthma/EIA in athletes:
- exercise tests - eucapnic voluntary hyperpnea

• Systematic screening for asthma in elite athletes
  number of misdiagnosis  better management of the disease

FURTHER READING
• BOOKS - Allergic and respiratory disease in sports medicine. Weiler JM.
Clinical Allergy and Immunology, Marcel Dekker, 1997 - Pulmonary pathophysiology. The essentials. Fifth Edition. West JB. Williams & Wilkins, 1995

• ORIGINAL PAPERS – Dickinson JW, et al. Impact of changes in the IOC-MC asthma
criteria: a British perspective. Thorax. 2005 Aug;60(8):629-32. – Anderson SD, et al. Responses to bronchial challenge submitted for approval to use inhaled beta2-agonists before an event at the 2002 Winter Olympics. J Allergy Clin Immunol. 2003 Jan;111(1):45-50.

• REVIEWS - Anderson SD, Brannan JD. Methods for "indirect" challenge tests

including exercise, eucapnic voluntary hyperpnea, and hypertonic aerosols. Clin Rev Allergy Immunol. 2003 Feb;24(1):27-54. – Rundell KW, Jenkinson DM. Exercise-induced bronchospasm in the elite athlete. Sports Med. 2002;32(9):583-600.


				
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