Egyptian Board Thoracic Diseases cheat sheet

Alveolar gas equation: PAO2 = FiO2(PB − PH2O) − PaCO2/R, with R ≈ 0.8; at sea level on room air PAO2 ≈ 150 − PaCO2/0.8.

A-a gradient = PAO2 − PaO2; normal ≈ age/4 + 4 mmHg; widened gradient indicates V/Q mismatch, shunt, or diffusion limitation rather than pure hypoventilation.

Oxygen content: CaO2 = 1.34 × Hb × SaO2 + 0.003 × PaO2; the dissolved component is negligible at atmospheric pressure.

Oxygen delivery: DO2 = CO × CaO2; tissue hypoxia can result from low cardiac output despite normal SaO2.

West zones: zone 1 apex (PA > Pa > Pv) → dead space; zone 2 middle (Pa > PA > Pv) → Starling resistor; zone 3 base (Pa > Pv > PA) → perfusion.

Compliance = ΔV/ΔP; normal static lung compliance ≈ 200 mL/cmH2O; ARDS and fibrosis reduce compliance, emphysema increases it.

Shunt equation: Qs/Qt = (CcO2 − CaO2)/(CcO2 − CvO2); shunt does not correct with supplemental oxygen.

Hypoxic pulmonary vasoconstriction diverts blood from poorly ventilated units; global hypoxia causes pulmonary hypertension.

CO2 transport: ~70% as bicarbonate via carbonic anhydrase, ~23% carbaminohemoglobin, ~7% dissolved; Haldane effect enhances CO2 unloading in lungs.

Spirometry obstruction: FEV1/FVC < 0.70 post-bronchodilator (or < LLN); severity graded by FEV1 % predicted (GOLD: ≥80 mild, 50–79 moderate, 30–49 severe, <30 very severe).

Bronchodilator response: ≥12% and ≥200 mL increase in FEV1 or FVC indicates significant reversibility.

Restrictive pattern: reduced FVC with preserved or increased FEV1/FVC; confirm with reduced TLC (<80% predicted).

DLCO < 75% predicted suggests parenchymal or vascular disease; adjust for hemoglobin and altitude.

Six-minute walk test: minimal clinically important difference ≈ 30 m in COPD; desaturation <88% indicates exertional hypoxemia.

Chest radiograph: silhouetting of the right heart border suggests right middle lobe; left hemidiaphragm elevation suggests left lower lobe or abdominal process.

CT pulmonary angiography is first-line for suspected PE in hemodynamically stable patients; V/Q scan preferred when contrast is contraindicated.

EBUS-TBNA is preferred for mediastinal staging of lung cancer; sensitivity >90% for paratracheal nodes.

Pleural fluid Light's criteria: exudate if protein ratio >0.5, LDH ratio >0.6, or LDH >2/3 upper normal serum.

Asthma control assessed by GINA: daytime symptoms, night waking, reliever use, activity limitation; step-up if uncontrolled despite adherence.

Asthma exacerbation: repeated salbutamol, ipratropium, systemic corticosteroids; add magnesium sulfate for severe unresponsive cases.

COPD GOLD ABE: A = 0–1 exacerbations and mMRC 0–1; B = 0–1 exacerbations and mMRC ≥2; E = ≥2 moderate or ≥1 hospitalization.

COPD inhaled therapy: LABA+LAMA for group B; add ICS if blood eosinophils ≥300 or history of asthma features.

Long-term oxygen therapy in COPD: PaO2 ≤55 mmHg or SaO2 ≤88%, or PaO2 56–59 with cor pulmonale or polycythemia; ≥15 h/day improves survival.

Bronchiectasis: high-resolution CT shows dilated airways with signet-ring sign; sputum culture guides antibiotics; airway clearance is cornerstone.

Cystic fibrosis diagnosis: sweat chloride ≥60 mmol/L on two occasions, or CFTR genotype plus characteristic phenotype.

Alpha-1 antitrypsin deficiency: test serum level in early-onset emphysema, basilar predominance, or family history; augmentation therapy for eligible patients.

CAP severity: CURB-65 (confusion, urea >7 mmol/L, RR ≥30, BP <90/60, age ≥65); score ≥2 consider hospitalization, ≥3 ICU assessment.

TB diagnosis: sputum AFB smear and culture, Xpert MTB/RIF for rapid detection and rifampicin resistance; culture remains gold standard.

Latent TB treatment options: 6–9 months isoniazid, 4 months rifampicin, or 3 months isoniazid+rifapentine weekly.

Active TB standard regimen: 2 months HRZE followed by 4 months HR; extend if cavitation or positive culture at 2 months.

Aspergilloma: pre-existing cavity with fungal ball; hemoptysis is common; treat with surgical resection or bronchial artery embolization.

Invasive aspergillosis: galactomannan antigen and CT halo sign; voriconazole first-line.

Pneumocystis jirovecii pneumonia: ground-glass opacities, elevated LDH, beta-D-glucan; treat with trimethoprim-sulfamethoxazole.

Parasitic pulmonary disease: Löffler syndrome from Ascaris; hydatid cyst from Echinococcus; avoid aspiration to prevent anaphylaxis.

Empyema: pleural fluid pH <7.20, glucose <60 mg/dL, LDH >1000, or loculation indicates drainage.

IPF: usual interstitial pneumonia pattern on HRCT (subpleural, basal, honeycombing); treat with pirfenidone or nintedanib; no immunosuppression.

Sarcoidosis: bilateral hilar lymphadenopathy, non-caseating granulomas; Löfgren syndrome (fever, erythema nodosum, arthritis, hilar adenopathy) has good prognosis.

Hypersensitivity pneumonitis: exposure history, centrilobular nodules and air trapping on HRCT; antigen avoidance and corticosteroids.

Asbestosis: diffuse interstitial fibrosis with pleural plaques; latency >20 years; increased risk of mesothelioma and lung cancer.

Silicosis: upper-lobe nodular fibrosis, eggshell calcification of hilar nodes; associated with TB and autoimmune disease.

Berylliosis: granulomatous disease resembling sarcoidosis; beryllium lymphocyte proliferation test confirms sensitization.

Connective tissue disease–associated ILD: NSIP pattern common in scleroderma; screen with PFTs and HRCT.

Pneumoconiosis prevention: exposure control, respiratory protection, and surveillance with chest imaging and spirometry.

Wells score for PE: >6 high, 2–6 moderate, <2 low; combine with D-dimer to rule out in low/intermediate probability.

D-dimer age-adjusted cutoff: age × 10 µg/L for patients >50 years; high sensitivity, low specificity.

PE risk stratification: sPESI or PESI; high-risk = shock or hypotension → systemic thrombolysis or embolectomy.

Anticoagulation for PE: DOACs preferred for most; LMWH for cancer-associated thrombosis; duration ≥3 months, extended if unprovoked or recurrent.

CTEPH: persistent dyspnea after PE; ventilation-perfusion scan is screening test; pulmonary endarterectomy is curative.

Pulmonary arterial hypertension: mean PAP ≥20 mmHg, PCWP ≤15, PVR >3 Wood units; treat with ERA, PDE5 inhibitor, or prostacyclin.

OSA diagnosis: apnea-hypopnea index ≥5 with symptoms or ≥15 regardless; STOP-BANG screening.

OSA treatment: CPAP is first-line; mandibular advancement device for mild/moderate; weight loss and positional therapy adjuncts.

Obesity hypoventilation syndrome: BMI ≥30, daytime PaCO2 ≥45 mmHg, sleep-disordered breathing; treat with CPAP or bilevel ventilation.

Lung cancer staging: TNM 8th edition; stage I–II resectable, IIIA multimodality, IV systemic therapy; mediastinal staging with EBUS or mediastinoscopy.

Non-small cell lung cancer: test EGFR, ALK, ROS1, PD-L1 before first-line systemic therapy; targeted therapy for actionable mutations.

Small cell lung cancer: limited stage → concurrent chemoradiotherapy; extensive stage → platinum-etoposide plus immunotherapy.

Malignant pleural effusion: cytology sensitivity ~60%; thoracoscopy increases yield; indwelling pleural catheter or pleurodesis for palliation.

Mesothelioma: asbestos exposure, pleural thickening, poor prognosis; pemetrexed plus platinum.

Solitary pulmonary nodule: >8 mm requires PET-CT or biopsy; low-risk <6 mm can be followed with interval CT.

Pneumothorax: tension → immediate needle decompression then chest tube; primary spontaneous may resolve with observation if small.

Pleural infection: chest tube drainage plus antibiotics; intrapleural fibrinolytics with DNase for loculated empyema.

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.

PEEP titration: higher PEEP for moderate-severe ARDS; prone positioning for PaO2/FiO2 <150 for ≥16 h/day.

Weaning: spontaneous breathing trial with PS 5–8 or T-piece for 30–120 min; assess rapid shallow breathing index <105.

Noninvasive ventilation: first-line for COPD exacerbation with acidosis (pH 7.25–7.35); contraindicated in altered consciousness or facial trauma.

Ventilator-associated pneumonia: occurs >48 h after intubation; diagnose with new infiltrate plus clinical signs; treat with broad-spectrum antibiotics de-escalated by culture.

Sepsis-associated hypotension: norepinephrine first-line; fluids 30 mL/kg crystalloid for initial resuscitation.

Permissive hypercapnia acceptable in ARDS and status asthmaticus; avoid if raised intracranial pressure.

Pediatric asthma: diagnosis supported by reversibility or bronchial challenge; inhaled corticosteroids are controller of choice.

Croup: barking cough, stridor; treat with dexamethasone and nebulized adrenaline for severe cases.

Bronchiolitis: RSV most common; supportive care; avoid routine bronchodilators or corticosteroids.

Cystic fibrosis newborn screening: immunoreactive trypsinogen followed by sweat chloride; early nutritional and airway clearance improve outcomes.

Primary ciliary dyskinesia: situs inversus, chronic rhinosinusitis, bronchiectasis; nasal nitric oxide <77 nL/min is supportive.

Congenital diaphragmatic hernia: pulmonary hypoplasia and persistent pulmonary hypertension; gentle ventilation and iNO as needed.

Immunodeficiency: recurrent sinopulmonary infections suggest antibody deficiency; check immunoglobulins and vaccine responses.

Pediatric OSA: adenotonsillectomy first-line for most children with obstructive sleep apnea.

Levels of evidence: systematic reviews/meta-analyses of RCTs highest; GRADE rates certainty and strength of recommendations.

Number needed to treat = 1/absolute risk reduction; confidence intervals indicate precision of effect estimates.

Randomized controlled trial: randomization reduces selection bias; intention-to-treat analysis preserves comparability.

Systematic review: PRISMA reporting; assess risk of bias with tools such as Cochrane RoB 2.

Informed consent: must disclose purpose, risks, benefits, alternatives, and right to withdraw; ensure voluntariness.

Research ethics: institutional review board approval; Declaration of Helsinki principles; vulnerable populations require additional safeguards.

Publication bias: funnel plot asymmetry; prospective trial registration reduces selective reporting.

Clinical practice guidelines: AGREE II assesses quality; recommendations should be based on systematic evidence review.