Section 1: Asthma and COPD 1

Question 1

Therapy for COPD exacerbation

Answer 1

Bronchodilators (inhaled) = nebulized albuterol

Ipratropium (inhaled)

Steroids = prednisone or methylprednisone

Antibiotics = ceftriaxone

Counseling

Influenza vaccine

Pneumococcal vaccine

Question 2

List the most important features of a severe asthma exacerbation

Answer 2

Hyperventilation/ increased respiratory rate

Decrease in peak flow

Hypoxia

Respiratory acidosis

Possible absence of wheezing

Question 3

Enumerate the minimum management for patients with SOB

Answer 3

Oxygen

Continuous oximeter

CXR

ABG

Question 4

What is the best test to determine a diagnosis of reactive airway disease in an asymptomatic patient suspected of being asthmatic?

Answer 4

Methacholine stimulation testing

Question 5

What class of drug is methacholine?

Answer 5

Synthetic acetylcholine

Question 6

What happens when methacholine is administered to asthmatic?

Answer 6

Methacholine will decrease FEV1 if the patient has asthma.

Question 7

Name the two most frequently used pulmonary function tests

Answer 7

FEV₁ (forced expiratory volume in one second)

FVC

Question 8

What is the normal adult FEV₁/FVC ratio?

Answer 8

> 75%

Question 9

Describe the obstructive pattern in PFT

Answer 9

An FEV 1/FVC ratio of 70%

Total lung capacity (TLC) will be increased in some obstructive processes, such as COPD, whereas it may be normal or increased in asthma.

Question 10

Name some obstructive lung disease

Answer 10

COPD

Asthma

Chronic bronchitis

Bronchiectasis

Question 11

What is the meaning of DL_CO

Answer 11

Diffusing capacity of carbon monoxide

Question 12

What does DL_CO measure?

Answer 12

Measures the gas exchange capacity of the capilary-alveolar interface

Question 13

Why is DLCO normal in asthma

Answer 13

Because the alveoli are not affected

Question 14

What is the DLCO in COPD

Answer 14

The DLCO in COPD is decreased because some alveoli are destroyed and unavailable for gas exchange.

Question 15

Describe the restrictive pattern in PFT

Answer 15

Low FEV1, low FVC, but with normal or increased FEV1/FVC

Decreased TLC

An FVC of 80% is suggestive of restriction when the FEV1/FVC ratio is normal.

Question 16

Examples of diseases with restrictive pattern on PFT

Answer 16

Obesity

Interstitial lung disease

Inflammatory/fibrosing lung disease

Kyphosis

Question 17

Define hypoxia (or hypoxemia)

Answer 17

Defined as a room-air O₂ saturation of 88%

or a PaO₂ of 55 mm Hg on ABG measurement

or evidence of cor pulmonale.

Question 18

Diagnosis: Hypoxia not responding to supplemental oxygen

Answer 18

Shunt physiology

Question 19

Examples of diseases with ventilation-perfusion (V/Q) mismatch

Answer 19

Asthma

COPD

Nonmassive pulmonary embolus (PE)

Pneumonia.

Question 20

Features of ventilation-perfusion (V/Q) mismatch

Answer 20

Responds to oxygen

Increased arterial-alveolar oxygen (A-a) gradient

Question 21

What is the common cause of hypoventilation?

Answer 21

Oversedation from medications

Question 22

Features of hypoventilation

Answer 22

Responds to O2

Characterized by a normal A-a gradient

Question 23

Features of hypoxia due to decreased diffusion

Answer 23

Responds to O2

Characterized by an A-a gradient

Associated with a very low DLCO.

Le, Tao; Bhushan, Vikas; Herman Bagga (2010-09-21). First Aid for the USMLE Step 3, Third Edition (First Aid USMLE) (Kindle Locations 11153-11157). McGraw-Hill. Kindle Edition.

Question 24

Features of hypoxia due to high altitude

Answer 24

Responds to O2

Characterized by a normal A-a gradient

Question 25

Causes of SOB due to shunt physiology

Answer 25

Acute respiratory distress syndrome Significant lobar pneumonia Patent foramen ovale Patent ductus arteriosus.

Question 26

Features of SOB due to shunt physiology

Answer 26

Typically does not respond to O2 Characterized by an increased A-a gradient

Question 27

Differential diagnosis of Asthma presenting as chronic cough

Answer 27

Allergic rhinitis Postnasal drip GERD

Question 28

Differential diagnosis of wheezing

Answer 28

Asthma Foreign body aspiration Laryngeal spasm or irritation GERD CHF

Question 29

In asthma management, can inhaled corticosteroids be used in pregnancy

Answer 29

Yes, they are safe

Question 30

What is the implication of a normal PaCO2 in during an episode of asthma exacerbation

Answer 30

A normal Pco2 suggests that the patient is tiring out and is about to crash ## Footnote

Question 31

Outline the management of acute asthma

Answer 31

Initiate short-acting β-agonist (albuterol) therapy (nebulizer or MDI) Administer a systemic corticosteroid such as methylprednisolone or prednisone Begin inhaled corticosteroids as well Follow patients closely with peak flows, and tailor therapy to the response Chronic antibiotics (without evidence of infection), anticholinergics, cromolyn, and leukotriene antagonists are generally not useful in this setting

Question 33

Rx for exercise induced asthma

Answer 33

Inhaled bronchodilator prior to exercise

Question 34

What is the management of acute shortness of breath in a patient with COPD?

Answer 34

Oxygen and arterial blood gas (ABG) Chest x-ray Albuterol, inhaled Ipratropium, inhaled Bolus of steroids (e.g., methyl prednisolone) Chest, heart, extremity, and neurological examination If fever, sputum, and/ or a new infiltrate is present on chest x-ray, add ceftriaxone and azithromycin for community-acquired pneumonia.

Question 35

When to intubate patients with COPD?

Answer 35

Do not intubate patients with COPD for CO2 retention alone. These patients often have chronic CO2 retention. **Only intubate if there is a worsening drop in pH indicative of a worse respiratory acidosis**. Serum bicarbonate is often elevated due to metabolic alkalosis as compensation for chronic respiratory acidosis. ## Footnote

Question 36

List the typical physical findings in COPD

Answer 36

Barrel-shaped chest Clubbing of fingers Increased anterior-posterior diameter of the chest Loud P2 heart sound (sign of pulmonary hypertension) Edema as a sign of decreased right ventricular output (the blood is backing up due to the pulmonary hypertension)

Question 37

Laboratory findings in COPD

Answer 37

EKG: Right axis deviation, right ventricular hypertrophy, right atrial hypertrophy Chest x-ray: Flattening of the diaphragm (due to hyperinflation of the lungs), elongated heart, and substernal air trapping CBC: Increased hematocrit is a sign of chronic hypoxia. Reactive erythrocytosis from chronic hypoxia is often microcytic. An erythropoietin level is not necessary. Chemistry: Increased serum bicarbonate is metabolic compensation for respiratory acidosis. ABG: Should be done even in office-based cases to assess CO2 retention and the need for chronic home oxygen based on pO2 (you expect the pCO2 to rise and the pO2 to fall). Pulmonary function testing (PFT): You should expect to find the following: – Decrease in FEV1 – Decrease in FVC from loss of elastic recoil of the lung – Decrease in the FEV1/ FVC ratio – Increase in total lung capacity from air trapping – Increase in residual volume – Decrease in diffusion capacity lung carbon monoxide (DLCO) caused by destruction of lung interstitium

Question 38

Chronic medical therapy for COPD

Answer 38

Tiotropium or ipratropium inhaler Albuterol inhaler Pneumococcal vaccine: Heptavalent vaccine, Pneumovax Influenza vaccine: Yearly Smoking cessation Long-term home oxygen if the pO2 \< 55 or the oxygen saturation is \< 88 percent

Question 39

Name two interventions that lower mortality in COPD

Answer 39

Smoking cessation Home oxygen therapy (continuous)

Question 40

Spot Diagnosis: A case of COPD at an early age (\< 40) in a nonsmoker who has bullae at the bases of the lungs. ## Footnote

Answer 40

Alpha-1 antitrypsin deficiency

Question 41

Rx for alpha-1 antotrypsin deficiency

Answer 41

Alpha-1 antitrypsin infusion

Question 42

What is the most accurate diagnostic test for bronchiectasis?

Answer 42

High-resolution CT scan of the chest. ## Footnote

Question 45

Diagnosis: Decreased TLC, Decreased RV, Decreased VC, Normal FEV₁, Normal FEV₁/FVC ratio, Normal DL_CO

Answer 45

Extra-parenchymal (extra-thoracic) restriction * Kyphosis * Obesity

Question 46

Diagnosis: Increased TLC, Increased RV, Decreased FEV₁, Decreased FVC, Decreased FEV₁/FVC ratio, Decreased DL_CO

Answer 46

COPD

Question 47

Diagnosis: Normal or Increased TLC, Normal or Increased RV, Decreased FEV1, Decreased FVC, Normal or Decreased FEV1/FVC ratio, Normal or Increased DLCO

Answer 47

Asthma

Question 48

Diagnosis: Decreased TLC, Decreased RV, Decreased FEV₁, Decreased FVC, Normal or Increased FEV₁/FVC ratio, Decreased DL_CO

Answer 48

Fibrotic (or Interstitial Lung) Disease

Question 49

List the minimum that should be done for all patients with shortness of breath (SOB)

Answer 49

Oxygen Continuous oximeter Chest X-ray Arterial blood gas (ABG)

Question 50

Causes of low DL_CO

Answer 50

Emphesema Pneumonectomy Interstitial lung disease pulmonary embolism Pulmonary HTN

Question 51

Arterial blood gases measurements

Answer 51

pH: 7.35 to 7.45 PCO₂: 33-45mmHg PO₂: 75-105mmHg

Question 52

What is A-a gradient?

Answer 52

A-a gradient is alveolar-arterial gradient (PAO₂-PaO₂ gradient). It is a useful calculation for the assessment of oxygenation. A-a gradient increases with age and is only valid in room air. It is calculated as follows: PA0₂-Pa0₂ gradient = 150 - 1.25 X PaCO₂ - PaO₂ i.e., A-a gradient = [150 - (1.25 X PaCO₂) - PaO₂] **This gradient is between 5 and 15 mmHg in normal young adults. It increases with all causes of hypoxemia except hypoventilation and high altitude**