9/22- Cases: Obstructive Lung Diseases Flashcards
- A 60-yo male with an 80-pack year history of smoking presents with progressive dyspnea on exertion and a chronic productive cough.
- A chest radiograph demonstrates typical changes in COPD.
- Pulmonary function testing reveals a forced vital capacity (FVC) of 3.2 liters (85% predicted) and FEV1 of 1.1 liters (56% predicted)
- Arterial blood gases: pH 7.40, PaC02 43, Pa02 62.
What changes on the chest radiograph are suggestive of COPD?
- Increased air space/retrosternal space
- Flat diaphragm?
What are the 2 broad categories of lung dysfunction defined by PFTs?
1. Obstructive airway disease
- Decreased FEV1/FVC (under 0.7) and FEV1 (under 80%)
2. Restrictive airway disease
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What disease processes commonly demonstrate obstruction?
- COPD (chronic bronchitis and emphysema)
- Asthma
- Bronchiectasis, cystic fibrosis
- Upper airway obstruction (tumors, vocal cord tumors…)
What are the requirements for qualification for long-term oxygen therapy?
- PaO2 < 55 mmHg or SaO2 < 88%
On room air (not currently experiencing exacerbation)
OR
- PaO2 < 59 mm Hg and evidence of at least one of the following:
- Pulmonary Hypertension (P wave > 3 mm in LII, LIII, or aVF
- Cor pulmonale (dependent edema)
- Erythrocytosis (Hct > 56%)
What factors may affect the prognosis of pts with COPD?
BODE index (prognosis)
- BMI (low BMI, < 21, -> increased mortality)
- Obstruction (lower FEV1)
- Dyspnea (measured by MRC dyspnea scale)
- Exercise
How is chronic bronchitis defined?
Clinically
- Chronic cough for at least 3 months
- Occurring at least 2 consecutive years
How is chronic bronchitis characterized pathologically?
- Submucosal hyperplasia of mucus glands
- Increased Reid index (Reid Index is ratio of submucosal glands to distance measured from endothelium to cartilaginous wall)
- Contributes to mucus plugs
- Typically neutrophilic inflammation (typical of COPD)
- Peripheral airway narrowing may be present
What are the 2 pathological classifications of emphysema?
- Which lobes affected
- Associations
(Emphysema = permanently enlarged airspaces due to destruction of tissue in alveolar-septal walls; lack of elastic recoil)
1. Centriacinar (centrolobular)- typically seen in smokers; upper lobe disease
2. Panacinar (panlobular)- typically seen with alpha-1 antitrypsin deficiency; lower lobe disease
- Begins in more distal airways: alveolar ducts and alveoli
If the patient (case below) had been 40 yo, what disease process might be important and who should be screened for this?
- A 60-yo male with an 80-pack year history of smoking presents with progressive dyspnea on exertion and a chronic productive cough.
- A chest radiograph demonstrates typical changes in COPD.
- Pulmonary function testing reveals a forced vital capacity (FVC) of 3.2 liters (85% predicted) and FEV1 of 1.1 liters (56% predicted)
- Arterial blood gases: pH 7.40, PaC02 43, Pa02 62.
Younger pt presenting with emphysema and airway obstruction should be evaluated for alpha-1-antitrypsin deficiency
Indications:
- Chronic bronchitis with airflow obstruction in a never-smoker
- Bronchiectasis, esp in absence of clear risk factors for the dz
- Premature onset of COPD, with moderate/severe impairment by (or before) age 50
- Family history of early onset COPD or α-1 antitrypsin deficiency
- Cirrhosis without apparent risk factors (since a1-AT deficiency causes liver cirrhosis)
Case)
- An asthma patient presents to the emergency room in severe respiratory distress.
- The patient receives vigorous treatment with inhaled beta-agonists.
- After 30 minutes of aggressive treatment, arterial blood gases revealed, on supplemental oxygen (2 liters/minute), pH 7.24, PaC02 60, and Pa02 of 100.
- The patient remains in respiratory distress. What is this patient’s acid base disorder?
- Is the degree of decrease in pH expected?
- What is the A-a difference?
- Respiratory acidosis due to hypoventilation
- If acute: 0.08*(60-40)/10 = 0.16, so that would predict a pH of 7.24
- A-a difference may be skewed because he’s on supplemental oxygen
What findings on physical exam demonstrate respiratory distress?
- What history/symptoms indicate severity?
- PR > 120/min
- RR > 30/min
- Pulsus paradoxus
- Accessory muscle use
- Abdominal paradox: when you inhale, diaphragm goes down and abdomen typically goes out; opposite signals inspiratory muscle (diaphragm) fatigue
- Silent chest: decreased/absent air entry sounds
- Altered mental status
What are some factors that may precipitate or aggravate asthmatic symptoms?
Predisposing factors: atopy, gender
Causes: allergens, occupational sensitizers like plastics, colder weather, medications (i.e. allergic response to aspirin)
Contributing factors: respiratory infections, small size at birth, obesity, air pollution, and smoking
What treatment is recommended for person in acute exacerbation of obstructive lung disease?
- Oxygen
- Short-acting bronchodilators Q20 min
- Monitor PEFR
- Maintenance: LABA + inhaled corticosteroids
What might be considered in your DDx of wheezing?
- Asthma
- Foreign object
- Tumor/malignancy
- Pulmonary edema
- Acute pulmonary embolism
- Vocal cord paresis (more stridor)
What pathological findings might be demonstrated in a patient with asthma?
- Sm hypertrophy (due to chronic irritation and contraction)
- Inflammation
- Thickening of basement membrane of epithelium
- Goblet cell metaplasia; possible mucus plugs (Curschmann spirals; due to goblet cells rather than submucosal gland hypertrophy seen in chronic bronchitis)
Describe pathogenesis of bronchiectasis
Destruction of normal muscle and elastic tissue in airways due to repeated inflammation and…
- Could be caused by cystic fibrosis
- Severe childhood infections (pneumonia)
What is the best way to diagnose bronchiectasis? Treatment?
HRCT
Treatment:
- Focal: surgical
- Diffuse: hypertonic saline, mucolytics, treat infection; could give prophylactic Abx (macrolides for anti-inflamms)
