Egyptian Board Thoracic Diseases flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Alveolar gas equation

PAO2 = FiO2(PB − 47) − PaCO2/0.8. At sea level on room air, PAO2 ≈ 150 − PaCO2/0.8; used to calculate A-a gradient and assess hypoxemia mechanism.

A-a gradient

Difference between alveolar and arterial oxygen tension. Normal ≈ age/4 + 4 mmHg. Widened in V/Q mismatch, shunt, or diffusion limitation; normal in pure hypoventilation.

Oxygen content formula

CaO2 = 1.34 × Hb × SaO2 + 0.003 × PaO2. Dissolved oxygen contributes minimally at atmospheric pressure; anemia reduces content despite normal saturation.

West lung zones

Zone 1 apex: PA > Pa > Pv, dead space. Zone 2 middle: Pa > PA > Pv, Starling resistor. Zone 3 base: Pa > Pv > PA, perfusion. Explains V/Q heterogeneity.

Spirometry obstruction criterion

Post-bronchodilator FEV1/FVC < 0.70 or below lower limit of normal defines obstructive defect; severity graded by FEV1 % predicted.

Bronchodilator response

Increase in FEV1 or FVC of ≥12% and ≥200 mL after bronchodilator. Indicates reversible airflow limitation, supporting asthma diagnosis.

Light's criteria

Pleural fluid is exudate if protein ratio >0.5, LDH ratio >0.6, or LDH >2/3 upper normal serum. Sensitivity high; misclassifies some transudates.

EBUS-TBNA

Endobronchial ultrasound-guided transbronchial needle aspiration for mediastinal lymph node sampling; sensitivity >90% for lung cancer staging, avoiding mediastinoscopy.

GOLD ABE groups

COPD classification: A = 0–1 exacerbations, mMRC 0–1; B = 0–1 exacerbations, mMRC ≥2; E = ≥2 moderate or ≥1 hospitalization. Guides inhaled therapy.

Long-term oxygen therapy criteria

COPD with PaO2 ≤55 mmHg or SaO2 ≤88%, or PaO2 56–59 with cor pulmonale or polycythemia. Use ≥15 h/day to improve survival.

Bronchiectasis signet-ring sign

HRCT finding of dilated bronchus with adjacent pulmonary artery, indicating bronchiectasis. Airway clearance and targeted antibiotics are mainstays.

CURB-65

CAP severity score: confusion, urea >7 mmol/L, respiratory rate ≥30, blood pressure <90/60, age ≥65. Score ≥2 consider admission; ≥3 assess ICU.

Xpert MTB/RIF

Rapid molecular test detecting Mycobacterium tuberculosis and rifampicin resistance in sputum; high sensitivity and specificity; culture remains gold standard.

Aspergilloma

Fungal ball in pre-existing lung cavity, often from prior TB; causes hemoptysis. Treat with surgical resection or bronchial artery embolization.

Pneumocystis jirovecii pneumonia

Opportunistic infection in immunocompromised patients; ground-glass opacities, elevated LDH and beta-D-glucan. First-line treatment is trimethoprim-sulfamethoxazole.

IPF treatment

Idiopathic pulmonary fibrosis with usual interstitial pneumonia pattern; treat with pirfenidone or nintedanib to slow progression. Immunosuppression is not recommended.

Löfgren syndrome

Acute sarcoidosis triad: fever, erythema nodosum, arthritis, with bilateral hilar lymphadenopathy. Usually self-limited with good prognosis.

Silicosis

Occupational lung disease from silica inhalation; upper-lobe nodular fibrosis, eggshell hilar calcification; increased risk of tuberculosis and autoimmune disease.

Wells score for PE

Clinical probability score: >6 high, 2–6 moderate, <2 low. Combined with D-dimer to rule out PE in low or intermediate probability.

CTEPH

Chronic thromboembolic pulmonary hypertension: persistent dyspnea after PE. V/Q scan is screening; pulmonary endarterectomy is potentially curative.

OSA diagnosis

Apnea-hypopnea index ≥5 with symptoms or ≥15 regardless of symptoms on polysomnography. CPAP is first-line therapy.

Lung cancer molecular testing

For non-small cell lung cancer, test EGFR, ALK, ROS1, and PD-L1 before first-line systemic therapy to guide targeted treatment.

Malignant pleural effusion

Pleural fluid cytology sensitivity ~60%; thoracoscopy improves yield. Palliate with indwelling pleural catheter or pleurodesis.

Tension pneumothorax

Life-threatening pneumothorax with hemodynamic compromise; immediate needle decompression followed by chest tube. Do not delay for imaging.

ARDS Berlin definition

Acute onset within 1 week, bilateral opacities, PEEP ≥5, PaO2/FiO2 ≤300. Severity: mild 200–300, moderate 100–200, severe <100.

Lung-protective ventilation

Tidal volume 6 mL/kg predicted body weight, plateau pressure ≤30 cmH2O, driving pressure ≤15. Reduces mortality in ARDS.

Rapid shallow breathing index

Respiratory rate divided by tidal volume in liters; <105 predicts successful weaning from mechanical ventilation during spontaneous breathing trial.

Pediatric croup treatment

Dexamethasone for all severities; nebulized adrenaline for severe stridor. Barking cough and inspiratory stridor are typical.

Cystic fibrosis sweat test

Sweat chloride ≥60 mmol/L on two occasions confirms CF; 30–59 mmol/L is intermediate. Newborn screening uses immunoreactive trypsinogen.

Primary ciliary dyskinesia

Situs inversus, chronic rhinosinusitis, bronchiectasis; nasal nitric oxide <77 nL/min is supportive. Autosomal recessive inheritance.

Number needed to treat

NNT = 1/absolute risk reduction. Indicates how many patients need treatment for one additional benefit; lower NNT means greater effect.

GRADE system

Rates certainty of evidence and strength of recommendations; considers risk of bias, inconsistency, indirectness, imprecision, and publication bias.