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)
