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Flashcards in Respiratory Deck (43):

For results to be consistent in spirometry, FVC and FEV1 have to be within what percentage?





What is a normal FEV1?



What is a normal FEV1/FVC ratio?




What is FEF25-75%?



Mean expiratory flow over the mid 50% of expiration



Describe a normal flow volume loop.

Top loop is expiration

bottom loop inspiration

PEF = airflow in large airways

FEF25-75% = small airways, effort independent

FEV1 = middle airways


What does this flow volume loop indicate?



What does this flow volume loop indicate?

Slow start


What does this flow volume loop indicate?

False start


What does this flow volume loop indicate?

Early termination


What does this flow volume loop indicate?

Variable effort


What does this flow volume loop indicate?

Not at TLC prior to start


What does a reduction in FVC indicate?

  • Reduced lung size
  • Restrictive lung disease or
  • severe air flow limitation.


What does a reduction in FEV1 indicate?

Airflow limitation or severe restrictive process. [earliest change associated with airflow limitation seen in small airways (FEF: 75 then 25-50)]


What do changes in FEV1/FVC ratio indicate?

Proportion of Vital Capacity expired in 1 second.

Normal is 80%

FEV1/FVC ratio is decreased in obstructive lung disease.

If <70%, COPD can be diagnosed.

In restrictive lung disease, both FEV1 and FVC are reduced, therefore FEV1/FVC ratio should be approximately normal or increased.


10 yr old girl with persistant wheeze and cough.

FVC 98%

FEV1 76%


FEF 25-75 34%

FEF50 44%

PF 77%

FIF 50% 116

Inspiratory loop normal

Concave expiratory loop = obstructive.

FVC good

FEV1 reduced

FEV1/FVC reduced

FEF 25-75 reduced


Obstructive picture - asthma


What do you expect to see in an obstructive picture in spirometry?

  • Low FEV1
  • Low FEF 25-75
  • Normal FVC
  • FEV1/FVC
  • Flow volume loop: Concave
  • Normal large airways – can reach PEF


  • Airways chockablock – air comes out slower like blowing through a straw
  • Bronchodilator responsiveness: >12% increase FEV1


14 yo boy with severe extensive bronchiectasis

  • FVC 85%
  • FEV1 42%
  • FEV1/FVC 42
  • FEF 25-75 13%
  • FEF50 15%
  • PF 69%
  • TLC 122%


Mod to severe obstructive lung disease

  • PEF reduced
  • Concave expiratory loop
  • FVC almost normal
  • FEV1 reduced
  • FEV1/FVC reduced
  • FEF 25-75 reduced
  • TLC high indicating air trapping

(FEV1/FVC ratio is decreased in obstructive lung disease)


What are the three main obstructive conditions?


Cystic Fibrosis



What is the main parameter to indicate obstructive lung disease in spirometry?



  • Normal >Lower limit of normal
  • Mild >70%
  • Moderate >50%
  • Severe >35%
  • Very severe <35%

- CF: FEV1 30% = 50% two year survival ... transplant


In obstructive airways disease, what is the most useful long-term measure of disease progression?


FEV1 is the most reproducible, most commonly obtained, and possibly most useful pulmonary function tests.

• objective measure of airflow in obstructive disease.

• FEV1 as a percentage of predicted norms is one of six criteria used to determine asthma severity. It provides an objective measure of airflow in obstructive disease.

• Lung hyperinflation can be adjusted for by FVC, which is why FEV1/FVC ratio of <80% for airflow limitation is used.

• Bronchodilator response with an improvement of >12% in FEV1 indicates obstruction.

• FEF25-75 considered by some to be more sensitive than the FEV1 for detecting early airway obstruction, but it has a wider range of normal values.


2008A Q36

A ten-year-old boy with severe bronchiolitis obliterans presents to the Emergency Department with increasing exercise intolerance over the previous week.
A capillary blood gas shows the following picture:
pH    7.29   [7.35 - 7.45]

pCO2    97 mmHg  [36 – 44 mmHg]

Bicarbonate (HCO 3 -)  45 mmol/L  [21 – 30 mmol/L]

Base excess  +18 mmol/L  [-3 – +3 mmol/L]

This result is most consistent with which of the following?

A. Acute on chronic respiratory acidosis.

B. Acute respiratory acidosis.

C. Chronic respiratory acidosis.

D. Mixed metabolic and respiratory acidosis.

E. Uncompensated metabolic acidosis. 

A. Acute on chronic respiratory acidosis
pH is acidotic.
CO2 is elevated indicating respiratory acidosis.
HCO3- and base excess are elevated indicating compensation for respiratory acidosis, indicates more chronic picture.
pH being low despite chronic compensation shows an acute on chronic picture.
B is incorrect because compensation in place - chronic.
C is incorrect because if chronic with such strong compensation, pH should be better.
D and E are incorrect because HCO3- would be low for metabolic acidosis


2 most common systems in primary ciliary dyskinesia?

1. respiratory

2. otological



A disorder characterized by the presence of a higher than normal level of methemoglobin (metHb, i.e., ferric [Fe3+] rather than ferrous [Fe2+] haemoglobin) in the blood.

Methemoglobin is a form of hemoglobin that contains ferric [Fe3+] iron and has a decreased ability to bind oxygen. However, the ferric iron has an increased affinity for bound oxygen.[1] The binding of oxygen to methemoglobin results in an increased affinity of oxygen to the three other heme sites (that are still ferrous) within the same tetrameric hemoglobin unit.

This leads to an overall reduced ability of the red blood cell to release oxygen to tissues, with the associated oxygen–hemoglobin dissociation curve therefore shifted to the left.


In a 10-year-old child with neuromuscular weakness, which of the following lung function tests best evaluates the degree of respiratory muscle weakness?

A. Forced expiratory volume in 1 second (FEV1).
B. Forced vital capacity (FVC).
C. FEV1/FVC ratio.
D. Functional residual capacity.
E. Maximal mid-expiratory flow

Forced vital capacity (FVC)

• Monitoring of patients with Duchenne Muscular Dystrophy includes 6 monthly pulmonary function testing, including FVC.

• FVC predicts development of hypercapnia and survival and a combination of FVC and blood gas results can be used to monitor disease progression.


Morquio's syndrome aka mucopolysaccharidosis IV

  • Abnormal heart development
  • Abnormal skeletal development
  • Hypermobile joints
  • Large fingers
  • Knock-knees
  • Widely spaced teeth
  • Bell-shaped chest (flared ribs)
  • Compression of spinal cord
  • Enlarged heart
  • Dwarfism
  • Heart Murmur
  • below average height for certain age


Oxygen dissociation curve - left shift(high affinity for O2)

1.Temperature decrease 

2. 2.3-DPG decrease 

3.p(CO2) decrease 

4.pH (Bohr effect) increase (alkalosis) 

5.type of hemoglobin fetal hemoglobin 



Oxygen dissociation curve - Right shift(low affinity for O2)

  1. Temp - Increase
  2. 2,3 DPG - Increase
  3. p(CO2) - Increase
  4. PH -Decrease(acidosis)
  5. Hgb- Adult Hgb


The calculation of Respiratory Compliance (Crs) in infants can be undertaken using the single-breath occlusion method. When using this technique, the most appropriate method of calculating respiratory compliance is:
A. the pressure at the airway opening recorded during occlusion, divided by flow.
B. the pressure at the airway opening recorded during occlusion, divided by total exhaled volume.
C. the time constant divided by the total exhaled volume.
D. the time constant divided by the airway opening pressure recorded during occlusion.
E. the total exhaled volume divided by pressure at the airway opening recorded during occlusion.

E. the total exhaled volume divided by pressure at the airway opening recorded during occlusion.


A 16-year-old girl is referred for evaluation of daytime tiredness.   She is reported to go to bed at 1.00 a.m. and to have difficulty rising in the morning for school.  At weekends she sleeps until early afternoon.  No medical or psychiatric symptoms are detectable. In addition to gradually advancing her bedtime to an earlier time, bright light therapy is recommended.
This is most effective if undertaken at which of the following time periods?

A. Early morning.
B. Late morning.
C. Mid afternoon.
D. Evening.
E. Prior to retiring.


A. Early morning.


Phototherapy — Exposure to bright light when awakening is an effective therapy for patients whose sleep onset insomnia is due to delayed sleep phase syndrome, a condition in which the onset of sleep is delayed because the individual's sleep-wake rhythm is longer than 24 hours.

Patients undergoing phototherapy sit in front of 10,000 lux light box (or a window with sunlight) for 30 to 40 minutes upon awakening (average indoor lighting is 300 to 500 lux, average sunny summer day is 100,000 lux). In addition, they markedly reduce their exposure to bright light in the evening (eg, they may keep their shades down and indoor lights dim). A response to therapy is generally evident after two to three weeks. Indefinite treatment is frequently necessary to maintain the benefits. In less severe cases, consistent awakening at a given time in the morning, followed by physical activity with exposure to outdoor light (eg, a walk outside, sitting next to a window with the shades and curtains open), may be sufficient even on a cloudy day.

Phototherapy may also be beneficial to patients whose insomnia is due to advanced sleep phase syndrome, a condition in which the individual desires sleep early and awakens early because their sleep-wake rhythm has shifted earlier. In this situation, exposure to bright light in the evening can help delay sleep onset.




2005, part b question 12

A nine-year-old girl with cystic fibrosis presents to clinic with a cough productive of brown sputum.  Her chest X-ray is shown opposite.
The most likely diagnosis is:

A. allergic bronchopulmonary aspergillosis.
B. atypical mycobacterium infection.
C. Burkholderia cepacia infection.
D. Staphylococcus aureus infection.
E. Stenotrophomonas maltophilia infection.


A. allergic bronchopulmonary aspergillosis.


A seven-year-old girl with a history of worsening dyspnoea on exertion is referred for lung function testing. The following results are obtained:

forced vital capacity (FVC)      70% predicted [80-100]
forced expiratory volume in 1 second (FEV1)    60% predicted [80-100]
forced inspiratory flow 50% / forced expiratory flow 50%
(FIF50%/FEF50%) ratio       0.5 predicted [0.9-1.1]

The most likely diagnosis is:
A. asthma.
B. extrathoracic airway obstruction.
C. interstitial lung disease.
D. poor effort.
E. respiratory muscle weakness

B. extrathoracic airway obstruction.
Variable extrathoracic obstruction — This flow-volume loop pattern is also known as dynamic or non-fixed extrathoracic obstruction. The pattern consists of a truncation of the envelope of the maximal inspiratory curve. During thoracic expansion with inspiration, the combination of atmospheric extraluminal pressure and negative (subatmospheric) intraluminal pressure results in decreased luminal size of the extrathoracic portion of the upper airway, thus accentuating the effect of any obstructive lesion in this region.

Turbulent flow and a Venturi effect also contribute to the drop in intratracheal pressure, producing further narrowing and flow limitation. In addition, the ratio of expiratory to inspiratory flow at 50 percent vital capacity — FEF(50 percent)/FIF(50 percent) — is elevated, with an average value of 2.2 (normal ratio: 1). Diseases that exhibit this pattern include laryngomalacia and tracheomalacia of the extrathoracic trachea, as well as structural or functional vocal cord abnormalities.


A six-week-old girl is referred to hospital for assessment of stridor, first noted a week previously.  She was born at term by normal vaginal delivery and weighed 2400 g.  She required no resuscitation and is bottle-fed and thriving.
On examination she is afebrile, alert and has a normal cry.  There are no dysmorphic features.  Biphasic stridor is heard in all positions, with a mild increase in respiratory work.  Her facial appearance is shown below.

What is the most likely diagnosis?

A.  Bilateral vocal cord paralysis.
B.  Bronchomalacia.
C.  Laryngomalacia.
D. Subglottic haemangioma.
E. Vascular ring.



D. Subglottic haemangioma.

Subglottic hemangioma associated with cutaneous hemangiomas in a “beard” distribution may be seen in PHACE syndrome 

P Posterior fossa brain malformations, most commonly the Dandy-Walker variant 

H Hemangiomas, particularly large, segmental facial lesions 

A Arterial anomalies 

C Cardiac anomalies and coarctation of the aorta 

E Eye abnormalities and endocrine abnormalities 

S* Sternal cleft, supraumbilical raphe, or both 


PFT in Cystic Fibrosis

Over time, the majority of CF patients develop an obstructive pattern on PFT. The most sensitive measures of early airway obstruction are increases in the ratio of residual volume to total lung capacity (RV/TLC) and decreases in the forced expiratory flow at 25 to 75 percent of lung volume (FEF25-75 percent). As disease progresses, spirometry reveals a decline in the forced expiratory volume in one second (FEV1) and the ratio of FEV1 to forced vital capacity (FEV1/FVC)

FEV1 is the most frequently measured in patients with CF.


Which of the following pathogens is most commonly associated with bronchiolitis obliterans?
A. Adenovirus.
B. Influenza virus.
C. Measles.
D. Mycoplasma pneumoniae.
E. Respiratory syncytial virus.

A. Adenovirus.

Adenovirus is the most likely virus to cause BO, but other pathogens including influenza, measles, and mycoplasma have also been identified in association with BO. BO is a prominent manifestation of chronic lung transplant rejection and can occur in children following transplantation. It is seen in children who have undergone hematopoietic cell transplantation.


A five-year-old boy presents with a 10-day history of purulent nasal discharge associated with fever and intermittent cough. His symptoms have failed to respond to a seven-day course of oral amoxycillin. He has had three similar episodes in the past year.
The most appropriate initial investigation is:
A. chest X-ray.
B. computed tomography (CT) scan of the facial sinuses.
C. culture of the nasal discharge with determination of antibiotic sensitivities.
D. plain X-ray of the facial sinuses.
E. serum immunoglobulin levels

B. computed tomography (CT) scan of the facial sinuses.



Treatment for obstructive sleep apnoea

1. Adenotonsillectomy

For children in whom adenotonsillectomy is contraindicated, who have OSA with minimal adenotonsillar tissue, who have persistent OSA despite adenotonsillectomy, or for whom there is a strong preference for a nonsurgical approach, go for positive airway pressure therapy.

Intranasal corticosteroids or leukotriene modifier therapy may be useful to treat mild OSA, and can be considered when adenotonsillectomy or CPAP/BPAP are not options for the child 


A 14-year-old girl with cystic fibrosis is reviewed in clinic. It is two months since her last review and in that time she has lost 2 kg in weight, and has had a 10% reduction in forced expiratory volume in one second (FEV1) but has had no recent wet cough. She has had normal stools. On examination her chest is clear.
Which one of the following is the most likely diagnosis?
A. Diabetes mellitus.
B. Gastro-oesophageal reflux.
C. Inadequate pancreatic supplementation.
D. Inadequate salt intake.
E. Recurrent active bronchitis.

A. Diabetes mellitus.


CF-related diabetes mellitus — Approximately 25 percent of individuals with CF develop CF-related diabetes (CFRD) by 20 years of age; the risk increases with age and varies with CF genotype and severity. CFRD is associated with clinical deterioration, including poor growth, deterioration of nutritional status, worsening lung function, and early death.    UPTODATE 


Which area of the lung has the highest ventilation/perfusion (V/Q) ratio in the erect position?
A. Anterior.
B. Diaphragmatic.
C. Middle.
D. Posterior.
E. Upper.

E. Upper


Question 68( 2000 part 1)
Interpret the flow volume loop shown below.
The findings are characteristic of which one of the following?
A. Interstitial disease.
B. Large airway obstruction.
C. Poor effort.
D. Skeletomuscular disease.
E. Small airway obstruction.

B. Large airway obstruction.



Saw tooth pattern in Pulmonary function tests

neuromuscular diseases,

Parkinson disease,

laryngeal dyskinesia,

pedunculated tumors of the upper airway,


upper airway burns,

obstructive sleep apnea (OSA).

snorers without sleep apnea

normal individuals.


Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)

Eosinophilic granulomatosis with polyangiitis (formerly called Churg-Strauss syndrome and also called allergic granulomatosis and angiitis) is a predominantly small-vessel vasculitis that is accompanied by asthma and eosinophilia. ANCA directed against both PR-3 and myeloperoxidase (MPO) may be seen 


Arterial carbon dioxide concentration is predominantly governed by:
A. alveolar volume.
B. dead space volume.
C. minute volume.
D. residual volume.
E. thoracic gas volume.

C. minute volume


An antenatal ultrasound reveals a right-sided thoracic lesion which appears to have a systemic blood supply. A computerised tomography (CT) scan performed after birth reveals an abnormal right lower lobe with air-filled cysts of varying size. Thickening and collapse are present within the same areas. Except for a cough the child has been asymptomatic but breath sounds are reduced in this area.
Which of the following is the most likely diagnosis?
A. Bronchogenic cysts.
B. Congenital lobar emphysema.
C. Cystadenomatoid malformation.
D. Polyalveolar lobe.
E. Pulmonary sequestration.

E. Pulmonary sequestration.