20 asthma/bronchiolitis 9 ventilation 4 neonate 4 ent ... · pdf filerespiratory data...

FRACP Course 2015

Respiratory Data InterpretationAssoc Prof Cass Byrnes

Respiratory Questions in FRACP

22 PFTs interpretation

20 Asthma/Bronchiolitis

16 Cough/Stridor/Croup

15 Sleep Medicine (↑)

15 Cystic fibrosis

15 Pneumonia/TB (↑)

13 CXR interpretation

10 ABG/Physiology

9 ventilation

4 neonate

8 congenital anomalies

4 ENT

1-2 Bx, Bronch Oblit, tonsillitis, sinusitis, foreign body, sarcoidosis, PCD, matetrnal smoking

Respiratory Questions account for 6-12% (11-2006) (9-2007) (9-2008) (18-2009) (14-2010) (7-2011)

NB: Many will have flow volume loop, ABG, CXR

Spirometry

Draw a normal flow volume loop.

Lung function indications1. Diagnosis Evaluation of symptoms (cough, wheeze)

Evaluation of signs (hyperinflation, crackles)

Investigations of abnormal findings (CXR, SaO2)

2. Monitoring Effectiveness of therapy

Course of disease / prognosis

Detect pulmonary adverse events

3. Evaluation of disease / impairment Assessment of disease severity

Assessment of operative risk

4. Research outcomes

Range of lung function testing Spirometry

Lung volumes

Airways resistance

Diffusion capacity

Maximum mouth pressures

Brnchodilator challenges

Exercise testing

Provocation challenges

NiOx testing

Flow Volume Loop

Flow (L/s)

Volume (L)

Expiratory

Inspiratory

Label axes and inspiratory/expiratory sections

Flow Volume Loops - normal

FEV1/FVC ratio

FEV1

Flow(L/s)

Volume (L)

Calculated -FEV1cannot be read off this graph

Residual volumeFVC

Peak flow

Flow Volume Loop

Mid expiratory flow

Mid inspiratory flow

Question In the performance of spirometry in 6-12 year old children, the flow volume curves should appear similar in configuration on repeat testing. What is the maximum allowable variation on repeat testing?

A. 5%

B. 10%

C. 15%

D. 20%

E. 25%

paper

Variations & QualityBody position FVC 7-8% ↓supine 1-2% ↓sitting

Neck position ↑ with hyperextension

Effort

Circadian rhythms ↓morning ↑ afternoon

Based on height (or arm span), age, gender

Best of 3 attempts

Max of 8 attempts

Reproducibility within 5%

Prior to test No bdr for 6 hours No LABA for 12 hours No meal for 1 hour

Flow volume loops - abnormalExpiratory

InspiratoryWhat are the abnormal features?What diseases would you see this in?

FLOW(L/s)

VOLUME (L)

Flow volume loops - abnormal

Obstructive loop – eg asthma, cystic fibrosis

Peak flow is (usually) lower

Concave expiratory curve

Calculated FEV1 will be lower (FEV1/FVC < 70%)

FEF 25-75 lower

Inspiration relatively preserved


What are the abnormal features?What diseases would you see this in?

Flow(L/s)

Expiratory

Volume (L) Inspiratory

Flow volume loops - abnormalRestrictive – eg neuromuscular disease, chest wall problems,

interstitial disease

Configuration of loop is narrowed because of reduced exhaled volume

Flow rates are preserved because of elastic recoil of lungs

FEV1/FVC ratio is increased


Describe this loop - Possible problem?

Flow(L/s)

Expiratory



Variable extra thoracic obstruction – eg vocal cord paralysis, vocal cord dysfunction

During expiration the vocal cords are passively blown aside

During inspiration vocal cord moves passively with the inhalation and obstructs the glottis


Flow(L/s)

Expiratory

Volume (L) InspiratoryDescribe this loop - Possible problem?

Flow volume loops - abnormalVariable intrathoracic obstruction – eg tracheomalacia

During expiration there is loss of support resulting in resulting in a narrow trachea and reduced flow

During forced inspiration the negative pleural pressure holds the floppy trachea open



Flow(L/s)

Expiratory



Fixed obstruction of upper airway – eg tracheal stenosis, bilateral vocal cord paralysis, (goitre)

Inspiration and expiration are limited equally

Flow Volume Loops - abnormal

Flow(L/s)

Volume (L)

Expiratory

InspiratoryDescribe this loop - Possible problem?


Poor effort

Loss of loop contour

Inspiration over extending compared to expiration suggesting not started from full lung capacity


Flow(L/s)

Volume (L)


Expiratory

Inspiratory


Hyperventilation

Reduced expiratory and inspiratory efforts


Flow(L/s)

Volume (L)

Expiratory

InspiratoryDescribe this loop - Possible problem?


coughing

After longstanding respiratory symptoms in a 14 yr old girl on no medication this CXR and flow volume loop is most consistent with?

A Abnormal ciliary beat frequency

B Production of green sputum

C Foreign body

D High sweat chloride measurement

E High Immunoglobulin E levels

Question

In obstructive airways disease the most useful long-term measure of disease progression is:

A. Forced expiratory flow 25-75% (FEF25-75%)

B. Forced expiratory flow 50%

C. Forced expiratory flow in one second (FEV1)

D. Forced vital capacity (FVC)

E. Peak expiratory flow (PEF)

paper

FEV1Values

CFFEV1 < 30% : 50% 2 year survival – consider transplant referral

DMD FVC < 60% : REM sleep disordered breathing

FVC < 40% : NREM/REM sleep disordered breathing

FVC 20% : Daytime respiratory failure

Normal >LLN (N >75%-85%, varies with age)

Mild >70%Moderate >50% Severe >35%Very severe <35%

Question

Which spirometry measure is the most sensitive in children with small airways disease

A. FVC

B. FEV1

C. FEF 25%-75%

D. Peak flow.

E. FEV1/FVC ratiopaper

Examples of Incorrect Manouevres Question

Which of the following is the chief determinant ofintra-thoracic airway resistance in normalchildren?A. Airway lengthB. Alveolar pressureC. Lung elastic recoilD. Lung volumeE. Number of conducting airways

paper

Airway Resistance

• Nasal airway = 40-50% of total resistance• Resistance through a single small airway is high, but there are so many of

them, airway resistance is highest in the intermediate bronchi (4th to 8th gen)• Airway resistance decreases as lung volume increases because the airways

distend as the lungs inflate, and wider airways have lower resistance• Lung elastic recoil is the major determinant of TLC and RV

http://oac.med.jhmi.edu/res_phys/Encyclopedia/AirwayResistance/AirwayResistance.HTML

Physiology

Poiseuille’s Law v = πr 4 p/8cl

Where: v= flow, r=radius, p=pressure, c=viscosity constant, l = length. Because radius to the 4th makes a big difference.

The airways are not rigid- upper – narrow with inspiration, dilate with expiration- lower – dilate with inspiration, compressed by expiration

EMQ For each flow volume loop given – select the most likely clinical case from those below

A. 10 year old boy with Duchennes Muscular Dystrophy under-going routine respiratory assessment

B. An ex VLBW 26week gestation infant who required prolonged respiratory support including ventilation now 6 years of age

C. 6 year old boy being evaluated for cough who appears otherwise well

D. 15 year old boy with severe bronchiectasis being referred for transplantation assessment

E. 8 year old boy with Morquio syndrome and significant tracheomalacia

EMQ For each flow volume loop given – select the most likely clinical case from those below

A.14 year old girl with CF and significant lung disease for ongoing respiratory assessment

B. 12 year old boy with previous severe adenoviral pneumonia being evaluated for ongoing respiratory disease with a CT scan showing a heterogeneous ground glass mosaic pattern

C. 7 year old girl who has been recently noticed to have SOB on exercise since starting school

D. A 9 year old girl with developmental delay being evaluated for cough

E 12 year old girl with asthma who still has some bronchodilator responsiveness despite being on IHCS & LABA (not taken before LFTs)

Diffusion Factor

CO → into lungs → across membranes → attach to Hb

Diffusion difficulties:Interstitial lung disease

Confounding factors:Low volume

alveolar volume, resection

Low Hbanaemia

Low blood flowshunt

Diffusion factorDLCO = CO inspired – CO expired (presented as %)

CO inspired DLCO corrected – corrected for Hb

KCO = DLCO corrected for Hb & Alveolar volume

Respiratory Pressures in NMD

Options used

Mouth pressures

Sniff pressures

Cough flow.

Inspiration= diaphragmatic strength.

Expiration = abdominal & intercostal muscle ability.

Paper – ages ago

Assessment of respiratory muscle strength- especially applicable to determine ability to cough & clear secretions.

Respiratory Pressures in NMD

Options used

Mouth pressures

Sniff pressures

Cough flow.

Inspiration= diaphragmatic strength.

Expiration = abdominal & intercostal muscle ability.

Paper – ages ago

Assessment of respiratory muscle strength- especially applicable to determine ability to cough & clear secretions.

Compliance

C = ∆ V ∆ P

How distensible it is

↓ RDS, atelectasis, surfactant

↓ surfactant deficiency

(↑ old age, emphysema)

Arterial Blood Gases

Acid-Base Assessments

1. pH - Look at the pH: acidosis, alkalosis, normal

2. Pattern:pCO2 – respiratory componentHCO3 – metabolic component

3. Clues – Clinical context and/or other biochemistry results ?suggestive of a particular disorder

NB: PaO2 is not part of acid base analysis– it is an indication of oxygen status

Acid base disorders – common patterns.

Respiratory Acidosis acid pH high CO2

acute – HCO3 normal chronic – HCO3 high

Respiratory Alkalosis alkali pH low CO2

HCO3 normal or low

Metabolic Acidosis acid pH low HCO3

CO2 normal or low

Metabolic Alkalosis alkali pH high HCO3

CO2 normal/high

Mixed (both) acidosis: acid pH, high CO2, low HCO3

Acid base disorders.Respiratory AcidosisAirway obstructionAcute resp failureAsthma CNS depression

Respiratory Alkalosis HyperventilationAspirin overdose

Metabolic Acidosis Sepsis Tissue ischaemia Renal failure Diarrohea Paracetamol overdose

Metabolic Alkalosis GI loss of H+ - vomiting Diarrohea with excess Cl loss Cl- loss with hypovolaemia (CF) Renal loss of H+ - diuretics HCO3 administration

QuestionThe following arterial blood gas results are obtained.

pH 7.31 [7.36-7.44]PaCO2 29mmHg [35-46]

PaO2 80mmHg [80-100]Bicarbonate 14mmol/L [22-26]

The best explanation for these results is:A. Acute respiratory acidosisB. Chronic respiratory acidosisC. Chronic respiratory alkalosisD. Metabolic acidosisE. Metabolic alkalosis

QuestionA 10 year old boy with severe bronchiolitis obliterans presents

to the ED dept with increasing exercise intolerance over the previous week.

A capillary gas shows the following picture:pH 7.29 (7.35-7.45)pCO2 97mmHg (36-44mmHg)HCO3 45 mmol/L (21-30 mmol/L)BE +18 mmolL (-3 to +3mmol/L)

The result is most consistent with which of the following?A. Acute on chronic respiratory acidosisB. Acute respiratory acidosisC. Chronic respiratory acidosisD. Mixed metabolic and respiratory acidosisE. Uncompensated metabolic acidosis

paper

QuestionAn eight-year-old boy is admitted with an episode of acute asthma. Hisoxygen saturation is 92% in air. He is prescribed prednisolone 1 mg/kgand hourly salbutamol 12 puffs. Three hours later his oxygen saturationin air has dropped to 89%. He looks well and is less distressed thanwhen admitted. He has widespread wheeze with good air entry.

Based on these findings, the most appropriate next step in hismanagement is:

A. Add ipratroprium bromideB. Blood gas analysisC. Change to intravenous salbutamolD. Chest X-ray to rule out a pneumothoraxE. Reduce frequency of salbutamol

paper

QuestionIn a patient presenting with a severe acute exacerbation of asthma, arterialblood gases on breathing room air show:

PaCO2 31 mmHg [36-44] (4.1kPa)PaO2 59 mmHg [80-100] (7.9kPa)pH 7.47 [7.36-7.44]

The hypoxaemia worsens with the administration of an intravenous beta-2agonist bronchodilator. The PaCO2 is unchanged. Which one of the followingmechanisms best explains the worsening of this patient’s hypoxaemia?

A. Increase in cardiac outputB. Increase in oxygen consumption by skeletal muscleC. Peripheral systemic arterial dilatationD. Pulmonary arterial dilatation in low ventilation-perfusion ratio (V/Q) unitsE. Pulmonary vasoconstriction

paper

Asthma physiology• Bronchospasm, mucus plugging, & edema in peripheral airways→ air trapping.• Obstruction & hyperinflation and therefore hypoxia → decreased alveolar

perfusion. • This → V/Q mismatch.

• Early acute asthma – hypoxemia triggers an increase in minute ventilation (hyperventilation). Differences in O2 & CO2 dissociation curves allow over-ventilated units to compensate for under-ventilated units for CO2 but not O2.

• Can get respiratory alkalosis.

• As asthma progresses, V/Q mismatch increases resulting in normal or high CO2(and worsening hypoxia). Can get respiratory acidosis & then metabolic (mixed) acidosis is a late development.

• B2 agonists result in bronchial airway smooth muscle dilatation (bronchodilation) but also vasodilation resulting in increased perfusion (cardiac output) to poorly ventilated alveolar units.

http://www.emedicine.com/ped/topic2150.htmSalbutamol & hypoxia: Tal A et al, Chest 1984; 86: 868-869

Oxygen Dissociation Curve

Reduced Hb affinityfor O2 → better tissue delivery

Left Right

↓ H+ ions ↑ H+ ions

↓ temp ↑ temp

↓ pco2 ↑ pco2

↓ 23DPG ↑ 23DPG

↓ ATP in cells ↑ ATP in cells

↑ carboxyHb ↓ zinc

↑ metHb

Carbon dioxide

Radiology

Shape of chest and appearance of bones change with age

A. Bronchiolitis

B. Enlarged heart and cardiac failure

C. Normal thymus

D. Azygous lobe

E. Right upper lobe consolidation

3 month old boy with mild ongoing respiratory distress following a recent RSV positivebronchiolitis infection. The CXR shows: A. Bronchiolitis

B. Enlarged heart & cardiac failure

C. Normal thymus

D. Azygous lobe


A. Bronchiolitis D. Azygous lobe

B. Enlarged heart & cardiac failure E. Right upper lobe

C. Normal thymus consolidation

A. Bronchiolitis


C. Normal thymus

D. Azygous lobe


A. Bronchiolitis


C. Normal thymus

D. Azygous lobe


A. Bronchiolitis


C. Normal thymus

D. Azygous lobe


The infant CXR

thymus

A BronchoscopyB Lung function testsC CT scan of his chestD Ciliary biopsyE Sweat test

2 year old boy with episodes of otitis media, runny nose, 1 pneumonia and on resolution of the pneumonia, this CXR. What is the best next test?

3 year old boy with a 4 day history of cough having recently started at playcentre and has an otherwise unremarkable past history. Your next step in viewing these CXR.

This 2 month old term infant presented with tachypnoea and increasing work of breathing. The child was previously well and thriving. Which of the following is true as regards the most likely diagnosis:

A. BronchiolitisB. Congenital diaphragmatic hernia C. Congenital Lobar emphysemaD. Vascular ringE. Congenital pulmonary airway malformation

This infant had significant respiratory distress at birth and grew Staph Aureus.

This is the CXR at Day 5 and shows:

A. Congenital pulmonary airway malformation

B. Congenital diaphragmatichernia

C. Congenital lobar emphysemaD. PneumatocoeleE. Pneumothorax

A. Congenital pulmonary airway malformation

B. Congenital diaphragmatic hernia

C. Congenital lobar emphysema

D. PneumatocoeleE. Pneumothorax

This infant had significant respiratory distress at birth and grew Staph Aureus.

This is the CXR at Day 5 and shows:

Following an URTI, this 12 year old boy has had a cough, sweats, exercise intolerance, loss of weight & become increasingly breathless over the last 2 weeks. You think there is also some stridor on examination.

Looking at the CXR you think he has:A. LymphomaB. Pneumonia and effusionC. TBD. CardiomyopathyE. Neuroblastoma

Made up




Looking at the CXR you think he has:A.Lymphoma

B. Pneumonia and effusion

C. TB

D. Cardiomyopathy

E. Neuroblastoma

Describe the type of changes seen in the next 3 slides of infants with respiratory disease?

Neonatal CXRs

1. Pneumonia - effusion

2. Asthma – pneumothorax – cong lobar emphysema – bronchiolitis

3. Hilar adenopathy (TB) - central tumour - cardiac

4. CPAM – cong diaphragmatic hernia – pneumatocoeles – cong lobar emphysema – lung cysts

5. Miliary presentation – CMV, TB, LIP, PCP

6. Neonatal – CLD, surfactant deficiency, interstitial lung disease

Radiology sequences:Resources

Flow-volume loopshttp://www.spirometrie.info/fvc.html

Flow volume loops interpretation ATS/ERS Guideline: ERJ 2005;26:948-968

RadiologyThe Neonatal CXR & Interpretation of the Paediatric Chest

Xray. R Arthur.

“Respiratory Physiology: The Essentials.” John B West (Lippincott Williams and Wilkins) 8th edition.

USE THE RESOURCES TO KEEP YOU GOING

GOOD LUCK

20 asthma/bronchiolitis 9 ventilation 4 neonate 4 ent ... · pdf filerespiratory data...

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