Step 3 · 8–10%

Respiratory System

Asthma, COPD, pneumonia, clots, nodules and failing lungs, in the office and the ICU.

Asthma

Prove variable airflow obstruction, use ICS-formoterol as the reliever, check technique before stepping up, and give systemic steroids early in attacks.

Rules to know

Episodic wheeze, cough or chest tightness → spirometry; FEV1 rise ≥12% and ≥200 mL after bronchodilator supports asthma
Normal spirometry, asthma still suspected → methacholine challenge; a negative test makes asthma unlikely
Reliever inhaler for patients 12 and older → as-needed budesonide-formoterol rather than albuterol alone
Mild asthma, symptoms less than daily → as-needed low-dose ICS-formoterol only; no daily controller needed
Symptoms most days or waking weekly → low-dose ICS-formoterol daily and as needed (maintenance and reliever)
Still uncontrolled on medium-dose ICS-formoterol → add LAMA, check eosinophils and IgE, refer for biologics
Severe eosinophilic or allergic asthma despite high-dose ICS-LABA → specialist biologic (anti-IgE, anti-IL-5, anti-IL-4R, anti-TSLP)
Before stepping up → check inhaler technique, adherence, triggers, rhinitis, reflux, obesity and smoking
Well controlled for 3 months → step down slowly; keep some ICS in persistent asthma
LABA without ICS in asthma → never; it raises asthma deaths
Talks in words, accessory muscles, SpO2 under 90%, PEF ≤50% → severe attack
Asthma attack → repeated SABA (add ipratropium if severe), oxygen to 93–95%, systemic steroid within 1 hour
Severe attack not responding to bronchodilators → IV magnesium; ICU if worsening
Drowsy, silent chest, PaCO2 normal or rising → impending respiratory failure; prepare to intubate
PEF after ED treatment → ≥70% discharge; under 40% admit; between, decide by risk factors
Discharge after an attack → prednisone 5–7 days without taper, start or raise ICS, action plan, review within 1 week
Symptoms only with exercise → SABA or ICS-formoterol before exercise plus warm-up; daily ICS if symptoms persist
Pregnancy → continue ICS, budesonide best studied; uncontrolled asthma harms the fetus more than the drugs
Child 5–11 with moderate persistent asthma → low-dose ICS-formoterol daily and as reliever
Child under 5 who wheezes only with colds → short daily ICS course at illness onset plus as-needed SABA
Asthma, nasal polyps and reactions to aspirin or NSAIDs → aspirin-exacerbated respiratory disease; avoid NSAIDs, leukotriene modifier, desensitization
Asthma with fleeting infiltrates, central bronchiectasis, IgE over 1000 → allergic bronchopulmonary aspergillosis; prednisone plus itraconazole
Wheeze unresponsive to inhalers, inspiratory stridor, flat inspiratory loop → vocal cord dysfunction; laryngoscopy during symptoms
Symptoms better on weekends and holidays → occupational asthma; serial peak flows at and away from work, remove exposure
Montelukast → boxed warning for mood changes and suicidality; not a preferred controller
Every asthma patient → written action plan, yearly flu vaccine, smoke-free home

Traps that cost points

Albuterol alone for newly diagnosed mild asthma→ SABA-only therapy leaves inflammation untreated and raises severe attacks; use as-needed ICS-formoterol.
Feeling reassured by a normal PaCO2 in a breathless asthmatic→ Attacks should drive PaCO2 down; a normal or rising value signals fatigue and coming failure.
Adding a biologic before checking inhaler technique and adherence→ Most poor control comes from technique, adherence or comorbidity; fix those first.
Salmeterol alone for nighttime symptoms→ LABA without ICS increases asthma deaths; always pair it with an inhaled steroid.
Stopping inhaled steroids when a patient becomes pregnant→ Poor control causes maternal hypoxia, preeclampsia and low birth weight; keep the controller.
Chest x-ray and antibiotics for every asthma attack→ Image only for suspected pneumonia, pneumothorax or poor response; most triggers are viral.
Tapering a 5-day prednisone burst→ Short courses do not meaningfully suppress the adrenal axis; stop without taper.
Labeling asthma from symptoms alone→ Document variable obstruction by spirometry or bronchoprovocation; many labeled patients have another cause.

COPD & bronchiectasis

In the Brain

Confirm fixed obstruction, escalate inhalers by symptoms and exacerbations, treat flares with short steroids, selective antibiotics and NIV, and give home oxygen only to those who qualify.

Rules to know

Smoker or exposed adult with chronic cough or exertional dyspnea → spirometry; post-bronchodilator FEV1/FVC under 0.70 confirms COPD
Every COPD diagnosis → test alpha-1 antitrypsin once, especially if young, basal emphysema or liver disease
Few symptoms, no exacerbations → one long-acting bronchodilator (LAMA or LABA)
Symptomatic COPD without frequent exacerbations → LAMA plus LABA in one inhaler
Two moderate exacerbations or one hospitalization a year → LAMA-LABA; add ICS if blood eosinophils ≥300
Exacerbations despite LAMA-LABA → add ICS if eosinophils ≥100; otherwise roflumilast or azithromycin
ICS in COPD → raises pneumonia risk; avoid with repeated pneumonia or eosinophils under 100
Long-term azithromycin → ECG for QT and hearing check first; works best in former smokers
Exacerbations on triple therapy with eosinophils ≥300 → biologic (dupilumab or mepolizumab) through a specialist
Exacerbation with more dyspnea, sputum volume or purulence → SABA with ipratropium, prednisone 40 mg for 5 days
Exacerbation with purulent sputum or needing ventilation → antibiotics 5–7 days (amoxicillin-clavulanate, doxycycline or macrolide)
Exacerbation with pH ≤7.35 and PaCO2 over 45 → bilevel NIV; intubate if it fails or the airway is unprotected
Oxygen during a COPD flare → titrate to SpO2 88–92%; excess oxygen worsens hypercapnia
Admit a COPD flare → severe dyspnea, new hypoxemia, confusion, failed outpatient care, serious comorbidity
Resting PaO2 ≤55 or SpO2 ≤88% when stable → long-term oxygen at least 15 hours daily
PaO2 56–59 with cor pulmonale, edema or hematocrit over 55% → long-term oxygen
Moderate resting or exertional desaturation only → home oxygen does not prolong life
What prolongs survival in COPD → stopping smoking and oxygen for chronic resting hypoxemia
Symptomatic COPD or recent hospitalization → pulmonary rehabilitation, starting within weeks of discharge
Persistent daytime hypercapnia weeks after a hypercapnic admission → home NIV reduces readmission
Every COPD patient → influenza, COVID-19, pneumococcal, Tdap and age-eligible RSV vaccines
Any smoker → advise quitting every visit; varenicline or combination nicotine replacement with counseling
Severe upper-lobe emphysema, hyperinflation, low exercise capacity after rehab → lung volume reduction surgery or endobronchial valves
Edema, loud P2 and hypoxemia in COPD → cor pulmonale; correct hypoxemia, diuretics for volume
Cardioselective beta-blocker indicated in COPD → give it; benefit outweighs the small bronchospasm risk
Daily purulent sputum, recurrent infections, dilated airways on CT → bronchiectasis; airway clearance, test for CF, immune deficiency, ABPA, mycobacteria
Bronchiectasis with ≥3 exacerbations a year → long-term macrolide; inhaled antibiotics if Pseudomonas

Traps that cost points

ICS-LABA as the first inhaler in a new COPD patient→ Dual bronchodilation works better with less pneumonia; add ICS only for exacerbations with raised eosinophils.
Targeting 98% saturation with high-flow oxygen in a hypercapnic flare→ Hyperoxia worsens V/Q matching and CO2 retention; aim for 88–92% with controlled oxygen.
Home oxygen for a resting saturation of 90%→ Only severe resting hypoxemia benefits; moderate desaturation does not improve survival.
A 14-day prednisone course for a COPD flare→ Five days works as well with less hyperglycemia and myopathy.
Intubating an alert hypercapnic COPD patient without trying NIV→ NIV lowers intubation and death in acidotic flares; intubate if it fails or contraindications exist.
Diagnosing COPD from a chest x-ray or smoking history alone→ Spirometry is required; many breathless smokers have HF, obesity or another disease.
Skipping alpha-1 testing in a 42-year-old with emphysema→ Early or basal emphysema suggests deficiency; augmentation and family testing follow.
Antibiotics for every COPD flare→ Give them for increased sputum purulence or when ventilation is needed; otherwise bronchodilators and steroids suffice.

Pulmonary embolism

In the Brain

Set pretest probability first and let it pick the test, anticoagulate while waiting when suspicion is high, and keep thrombolysis for PE with shock.

Rules to know

Suspected PE → estimate pretest probability first (Wells or clinical gestalt); it chooses the next test
Low probability and all eight PERC criteria negative → no further testing
Low or intermediate probability → D-dimer; a normal result excludes PE
Patient over 50 needing a D-dimer → age-adjusted cutoff (age × 10 µg/L) cuts false positives
High probability or positive D-dimer → CT pulmonary angiography
High suspicion and low bleeding risk → start anticoagulation before imaging returns
Contrast allergy or severe kidney disease with a clear chest x-ray → V/Q scan
Pregnant with suspected PE → leg ultrasound if leg symptoms; else V/Q if chest x-ray normal, CTPA if abnormal
Too unstable for CT → bedside echo showing RV dilation, or a proximal DVT, justifies treatment
Stable PE without contraindications → DOAC; apixaban or rivaroxaban need no heparin lead-in
PE with severe kidney failure, antiphospholipid syndrome or mechanical valve → heparin then warfarin, not a DOAC
PE in pregnancy → weight-based LMWH through delivery and ≥6 weeks postpartum (≥3 months total); no warfarin or DOAC
PE with active cancer → DOAC or LMWH; LMWH preferred with luminal GI or GU tumors
PE after surgery or major trauma → 3 months of anticoagulation, then stop
Unprovoked PE or persistent risk factor → extended anticoagulation with yearly review if bleeding risk is acceptable
Extended therapy after 6 months → reduced-dose apixaban 2.5 mg twice daily or rivaroxaban 10 mg daily
PE with SBP under 90 for 15 minutes or shock → systemic thrombolysis, alteplase 100 mg over 2 hours
Shock with a contraindication to lysis or failed lysis → catheter-directed therapy or surgical embolectomy
Normotensive PE with RV strain and troponin rise → anticoagulate, monitor closely; rescue lysis only if decompensating
Low-risk PE (sPESI 0, no RV strain, reliable home support) → outpatient DOAC
Acute PE or proximal DVT, anticoagulation impossible → retrievable IVC filter; remove once anticoagulation starts
Recurrent PE on therapy → check adherence, cancer and antiphospholipid syndrome; switch to LMWH
Dyspnea persisting 3 months after PE → V/Q scan for chronic thromboembolic pulmonary hypertension; refer for endarterectomy
Isolated subsegmental PE, no DVT, no cancer, low risk → clinical surveillance can replace anticoagulation
Unprovoked PE → age-appropriate cancer screening only; no whole-body CT
ECG in PE → sinus tachycardia is most common; S1Q3T3 is uncommon
Hypoxemia, petechiae and confusion 1–3 days after long-bone fracture → fat embolism; supportive care
Sudden hypotension during central line placement or removal → air embolism; left side down, head low, 100% oxygen

Traps that cost points

Ordering a D-dimer when pretest probability is high→ A negative result cannot exclude PE at high probability; go to CTPA.
Holding heparin until the CT is read in a high-probability patient→ Delay raises mortality; anticoagulate empirically unless bleeding risk is high.
Thrombolysis for normotensive PE with RV strain→ Routine lysis prevents some decompensation but raises major and intracranial bleeding; reserve it for shock or deterioration.
Placing an IVC filter alongside full anticoagulation→ Filters add no survival benefit and increase later DVT; use them only when anticoagulation is impossible.
Warfarin for PE in pregnancy→ Warfarin crosses the placenta and is teratogenic; use LMWH.
DOAC for PE in triple-positive antiphospholipid syndrome→ DOACs allowed more arterial clots in these patients; warfarin is preferred.
Stopping anticoagulation at 3 months after an unprovoked PE→ Recurrence risk stays high; offer extended therapy if bleeding risk allows.
CT of abdomen and pelvis to hunt cancer after unprovoked PE→ Extensive screening has not improved outcomes; history, exam, basic labs and routine screening are enough.

Pneumonia, fungal infection & tuberculosis

In the Brain

Score severity to choose home, ward or ICU, match empiric drugs to setting and risk factors, and test for latent TB only in people you would treat.

Rules to know

Cough, fever and a new infiltrate → community pneumonia; decide site of care with CURB-65 or PSI plus judgment
CURB-65 0–1 → outpatient; 2 → consider admission; ≥3 → admit and assess for ICU
Healthy outpatient → amoxicillin 1 g three times daily or doxycycline; macrolide only where resistance is low
Outpatient with major comorbidity (heart, lung, liver, kidney, diabetes, alcohol, asplenia) → amoxicillin-clavulanate or cephalosporin plus macrolide or doxycycline, or levofloxacin
Pneumonia admitted to the ward → ceftriaxone with azithromycin, or a respiratory fluoroquinolone alone
Severe pneumonia in the ICU → beta-lactam plus macrolide or fluoroquinolone; consider hydrocortisone
MRSA or Pseudomonas coverage in CAP → only with prior respiratory isolation, or recent admission with IV antibiotics in 90 days
Antibiotic length in CAP → usually 5 days once clinically stable; longer for complications
No improvement after 72 hours → look for empyema, abscess, resistant or unusual organism, or wrong diagnosis; CT chest
Pneumonia starting 48 hours or more after admission → antipseudomonal beta-lactam; add vancomycin or linezolid for MRSA risk; 7 days
Witnessed vomiting and aspiration, infiltrate within hours → chemical pneumonitis; supportive care, antibiotics only if it persists past 48 hours
Suspected aspiration pneumonia → usual CAP regimen; extra anaerobic coverage only for abscess or empyema
Alcohol use, poor teeth, cavity with air-fluid level → lung abscess; ampicillin-sulbactam for weeks
High fever, diarrhea, confusion, hyponatremia → Legionella; urine antigen, azithromycin or levofloxacin
Necrotizing pneumonia after influenza → S. aureus including MRSA; vancomycin or linezolid
HIV with CD4 under 200, subacute dyspnea and hypoxemia → Pneumocystis; TMP-SMX plus prednisone if PaO2 under 70
Desert Southwest exposure, erythema nodosum → coccidioidomycosis; Ohio-Mississippi valley caves or bird droppings → histoplasmosis
Neutropenic fever, nodules with halo sign → invasive aspergillosis; voriconazole
Preschool child with pneumonia, well enough for home → high-dose amoxicillin; most cases are viral
Infant 1–3 months, afebrile staccato cough, past conjunctivitis → Chlamydia trachomatis; azithromycin
Latent TB testing → only risk groups: contacts, immigrants from high-burden areas, HIV, immunosuppression, congregate settings, health workers
BCG-vaccinated, or unlikely to return for a reading → interferon-gamma release assay instead of skin test
Skin test cutoffs → ≥5 mm for HIV, contacts, immunosuppressed; ≥10 mm other risk groups; ≥15 mm no risk
Positive TB screen → chest x-ray to exclude active disease before latent treatment
Latent TB → 3 months weekly isoniazid-rifapentine or 4 months rifampin; isoniazid 6–9 months if rifamycins unsuitable
Isoniazid → add pyridoxine; stop if ALT over 3 times normal with symptoms or over 5 times without
Weeks of cough, night sweats, weight loss, upper-lobe cavity → active TB; airborne isolation, 3 sputum AFB smears plus NAAT
Active drug-susceptible TB → 2 months RIPE then 4 months isoniazid-rifampin, directly observed; report to the health department
TB drug toxicities → ethambutol vision (red-green color), rifampin orange fluids and interactions, pyrazinamide gout and hepatitis
Before a TNF inhibitor or similar biologic → screen for latent TB

Traps that cost points

MRSA and Pseudomonas coverage for every admitted CAP→ Without prior isolation or recent IV antibiotics plus admission, standard regimens suffice; overuse breeds resistance and C. difficile.
Antibiotics for every aspiration event→ An early infiltrate after witnessed aspiration is chemical injury; treat only if it persists or the patient worsens.
Treating latent TB before a chest x-ray→ Single-drug therapy for unrecognized active TB breeds resistance; exclude active disease first.
Stopping isoniazid for an asymptomatic ALT twice normal→ Mild rises are common and often settle; stop at over 3 times normal with symptoms or over 5 times without.
Testing low-risk adults for latent TB→ False positives outnumber true ones in low-risk people; test only when you would treat.
Repeat chest x-ray before discharge to document clearing→ Radiographic clearing lags recovery by weeks; base discharge on clinical stability.
Ten to fourteen days of antibiotics for uncomplicated CAP→ Short courses work as well once the patient is stable and cause fewer adverse effects.
A fluoroquinolone for every outpatient pneumonia→ Keep fluoroquinolones for comorbid or allergic patients; tendon, QT and C. difficile risks are real.

Lung nodules & lung cancer

In the Brain

Screen the right smokers yearly, follow incidental nodules by size and risk, sample what grows, and recognize lung cancer from its paraneoplastic clues.

Rules to know

Age 50–80, ≥20 pack-years, smoking or quit within 15 years → yearly low-dose CT
Stop LDCT screening → 15 years since quitting, or illness limiting life expectancy or fitness for surgery
Before the first screening CT → shared decision-making visit plus cessation counseling for current smokers
Incidental solid nodule → compare with old images first; solid and stable for 2 years means benign
Solid nodule under 6 mm → no follow-up if low risk; optional CT at 12 months if high risk
Solid nodule 6–8 mm → CT at 6–12 months, again at 18–24 months if high risk
Solid nodule over 8 mm → CT at 3 months, PET-CT, or biopsy depending on probability
Popcorn, central, laminated or diffuse calcification → benign pattern; no workup
Ground-glass or part-solid nodule → slow growth, follow up to 5 years; an enlarging solid part is suspicious
High-probability nodule in a fit patient → surgical resection for diagnosis and cure
Suspected lung cancer → CT chest and upper abdomen, PET-CT, then biopsy the site proving the highest stage
Before lung resection → spirometry and DLCO; low predicted postoperative values need exercise testing
Non-small cell stage I–II → lobectomy; stereotactic radiation if inoperable
Advanced nonsquamous NSCLC → test EGFR, ALK, ROS1, KRAS and other drivers plus PD-L1 before treatment
Small cell → central with early spread; chemotherapy with immunotherapy or chemoradiation, rarely surgery
Euvolemic hyponatremia with a central lung mass → SIADH from small cell
Hypercalcemia, low PTH, central cavitating mass → squamous cell making PTHrP
Proximal weakness that improves with repeated effort, dry mouth → Lambert-Eaton; look for small cell
Rapid cushingoid features with hypokalemia → ectopic ACTH, often small cell
Clubbing with painful swollen wrists and ankles → hypertrophic pulmonary osteoarthropathy; image the chest
Shoulder pain, Horner syndrome, apical mass → superior sulcus (Pancoast) tumor
Hemoptysis in a smoker over 40 with normal chest x-ray → CT chest, then bronchoscopy if unexplained
Massive hemoptysis → protect the airway, bleeding side down, bronchoscopy or bronchial artery embolization
Young nonsmoker, central endobronchial mass, hemoptysis or recurrent pneumonia → carcinoid; resection
Remote asbestos work, one-sided effusion and pleural thickening → mesothelioma; thoracoscopic pleural biopsy
Multiple round nodules in a patient with cancer → metastases (breast, colon, kidney, melanoma, sarcoma)
Smoker with lung cancer → quitting improves treatment response and survival
Chest x-ray or sputum cytology for screening → no mortality benefit; do not use

Traps that cost points

LDCT for a 45-year-old with 25 pack-years→ Screening starts at 50; counsel cessation now.
Continuing screening 16 years after quitting→ Benefit fades; stop once 15 years have passed since cessation.
Serial CT for a 4 mm nodule in a low-risk nonsmoker→ Malignancy risk is under 1%; no follow-up is needed.
Biopsying the lung primary when a mediastinal node is enlarged→ Sample the node that would upstage the tumor; one procedure then diagnoses and stages.
Referring small cell lung cancer for lobectomy→ It is usually disseminated at diagnosis; systemic therapy is the backbone.
Repeated antibiotics for a non-resolving infiltrate in a smoker→ Persistent consolidation can be an obstructing cancer; image and consider bronchoscopy.
Working up a nodule without looking for earlier imaging→ Obtain prior images when possible; stability decides more than size.
PET-CT for a 5 mm nodule→ Small nodules fall below PET resolution; follow them with size-based CT.

Interstitial lung disease, sarcoidosis & pulmonary hypertension

In the Brain

Restriction with a low DLCO sends you to high-resolution CT; exposure history, age and pattern then name the disease and the treatment.

Rules to know

Restrictive pattern, low DLCO, crackles → high-resolution CT; then exposure, drug and autoimmune history
Older patient, dry crackles, clubbing, basal subpleural honeycombing → idiopathic pulmonary fibrosis
IPF → nintedanib or pirfenidone, oxygen, rehab, early transplant referral; no steroids
New ILD → ANA, RF, anti-CCP and myositis antibodies; connective tissue disease is a frequent cause
Bilateral hilar nodes, erythema nodosum, ankle arthritis, fever → Lofgren sarcoidosis; NSAIDs, usually resolves, no biopsy
Other suspected sarcoidosis → biopsy noncaseating granulomas (EBUS of hilar nodes); exclude TB and fungus
Newly diagnosed sarcoid → eye exam, ECG, calcium, creatinine and liver tests
Sarcoid with symptomatic lung, eye, heart or nerve disease or high calcium → prednisone; methotrexate to spare steroids
Sarcoid with palpitations, heart block or syncope → cardiac MRI or PET; pacing or ICD as indicated
Hypercalcemia in sarcoid → granulomas make calcitriol; steroids, limit vitamin D and sun
Bird keeper, farmer or hot-tub user with recurrent fever and dyspnea → hypersensitivity pneumonitis; remove the antigen
Shipyard, insulation or brake work decades ago → asbestosis: lower-lobe fibrosis, calcified pleural plaques
Asbestos plus smoking → lung cancer risk multiplies; quitting matters most
Sandblasting, quarrying, engineered stone → silicosis: upper-lobe nodules, eggshell node calcification; test for latent TB
Coal miner with upper-lobe nodules → coal workers' pneumoconiosis; may progress to massive fibrosis
Aerospace, electronics or ceramics worker with granulomas → berylliosis; beryllium lymphocyte proliferation test
Cotton worker with chest tightness on the first workday of the week → byssinosis
New cough or infiltrates on amiodarone, nitrofurantoin, methotrexate or checkpoint inhibitor → drug lung injury; stop the drug, steroids if severe
Prior bleomycin → keep inspired oxygen as low as possible during surgery
Flu-like illness then patchy consolidations that fail antibiotics → organizing pneumonia; steroids
Young smoker with upper-lobe cysts and nodules, pneumothorax → Langerhans cell histiocytosis; stop smoking
Migratory infiltrates with eosinophilia after travel → Loeffler syndrome; stool ova and parasites, treat the worm
Peripheral infiltrates, eosinophilia, asthma history → chronic eosinophilic pneumonia; prednisone works fast
Exertional dyspnea, loud P2, RV heave, high RV pressure on echo → pulmonary hypertension; right heart catheterization confirms
Pulmonary hypertension found → look for left heart disease, lung disease or hypoxemia; V/Q scan for chronic clots
Group 1 pulmonary arterial hypertension → vasoreactivity test; responders get high-dose CCB, others combined targeted drugs
PH from left heart or lung disease → treat the underlying disease; most PAH drugs do not help
Systemic sclerosis → yearly echo and PFTs with DLCO for PAH and ILD

Traps that cost points

Prednisone for idiopathic pulmonary fibrosis→ Steroid-based regimens increased death in IPF; use antifibrotics.
Biopsying classic Lofgren syndrome→ The triad is diagnostic and usually remits; keep tissue sampling for atypical cases.
Treating asymptomatic hilar-node sarcoid with steroids→ Many cases resolve on their own; treat for symptoms, organ threat or falling lung function.
Calling calcified pleural plaques asbestosis→ Plaques mark exposure and are benign; asbestosis is parenchymal fibrosis.
Starting PAH drugs for pulmonary hypertension due to HF→ In left heart disease, pulmonary vasodilators can worsen pulmonary edema; treat the heart.
Diagnosing pulmonary hypertension from echo alone→ Echo estimates; right heart catheterization confirms and classifies before targeted therapy.
Skipping the V/Q scan in new pulmonary hypertension→ Chronic thromboembolic disease can be cured surgically and CT can miss it; V/Q screens best.
Continuing nitrofurantoin despite new interstitial infiltrates→ Drug lung injury improves once the drug stops; review the medication list first.

Pleural disease & pneumothorax

In the Brain

Tap new effusions unless heart failure clearly explains them, drain infected or bloody pleural spaces, and decompress tension pneumothorax before any film.

Rules to know

New effusion without an obvious HF cause → diagnostic thoracentesis
Bilateral effusions with clear HF → diurese first; tap if fever, pleuritic pain, unequal sizes or no response
Light criteria → exudate if fluid/serum protein over 0.5, fluid/serum LDH over 0.6, or fluid LDH over two-thirds of serum upper limit
Transudate → heart failure, cirrhosis, nephrotic syndrome, low albumin
Diuresed HF patient with borderline exudate → serum minus fluid albumin over 1.2 g/dL means transudate
Exudate → infection, cancer, PE, TB, autoimmune disease, pancreatitis
Pneumonia with effusion over 1 cm on ultrasound or decubitus film → sample it
Complicated parapneumonic effusion → chest tube plus antibiotics for pH under 7.2, glucose under 60, positive Gram stain or culture, or pus
Loculated empyema draining poorly → intrapleural tPA with DNase, or VATS decortication
Lymphocytic exudate with high adenosine deaminase → TB pleurisy; pleural biopsy for culture
Very low pleural glucose → empyema, rheumatoid arthritis, TB or cancer
Milky fluid with triglycerides over 110 mg/dL → chylothorax; thoracic duct injury or lymphoma
Recurrent malignant effusion → indwelling pleural catheter or talc pleurodesis
Exudate with negative cytology, cancer still suspected → repeat once, then thoracoscopic biopsy
Large-volume thoracentesis → remove about 1.5 L at most per session to avoid re-expansion edema
Tall thin young male smoker with sudden pleuritic pain → primary spontaneous pneumothorax
Primary pneumothorax with minimal symptoms → observation is acceptable even when moderate in size
Primary pneumothorax with significant breathlessness → needle aspiration or small-bore drain
Pneumothorax with COPD, CF or ILD → secondary; admit, usually a chest drain
Recurrent pneumothorax or persistent air leak → VATS with pleurodesis
After pneumothorax → quit smoking; fly only after confirmed resolution; no scuba diving without surgical pleurectomy
Hypotension, absent breath sounds, tracheal shift, distended neck veins → tension pneumothorax; needle decompression now, then chest tube
Open sucking chest wound → occlusive dressing taped on three sides, then chest tube away from the wound
Paradoxical chest wall segment after trauma → flail chest; analgesia, oxygen, ventilation if failing
Rib fractures in an older adult → strong analgesia including nerve blocks, incentive spirometry to prevent pneumonia
Traumatic hemothorax → chest tube; over 1500 mL at insertion or over 200 mL per hour → thoracotomy
Retching then chest pain, neck crepitus, left effusion → esophageal rupture; contrast study or CT, surgery, antibiotics
Chest wall pain reproduced by palpation, normal workup → costochondritis; NSAIDs and reassurance

Traps that cost points

Tapping bilateral effusions in a patient with obvious HF→ Typical HF effusions resolve with diuresis; sample only with atypical features or no response.
Treating an empyema with antibiotics alone→ Pus or complicated fluid needs drainage; antibiotics penetrate the pleural space poorly.
Waiting for a chest x-ray to confirm tension pneumothorax→ It is a clinical diagnosis; decompress first.
Draining 3 liters in one sitting→ Rapid large removal risks re-expansion pulmonary edema; stop near 1.5 L or with chest discomfort.
Chest tube for every small primary pneumothorax→ Stable, minimally symptomatic patients do well with observation.
Discharging a COPD patient with a small pneumothorax→ Secondary pneumothorax is poorly tolerated; admit and usually drain.
Assuming one negative cytology rules out a malignant effusion→ Cytology misses many cancers; repeat once and proceed to thoracoscopy if suspicion remains.
Clearing a recent pneumothorax patient for scuba diving→ Pressure changes can collapse the lung again underwater; diving is unsafe without surgical pleurectomy.

Respiratory failure, ventilation & sleep breathing

In the Brain

Use the A-a gradient to find the mechanism, protect lungs on the ventilator, choose high-flow or NIV by the problem, and confirm sleep apnea with the right test.

Rules to know

Hypoxemia with normal A-a gradient → hypoventilation (opioids, neuromuscular weakness, obesity) or high altitude
A-a gradient → PAO2 = 713 × FiO2 − PaCO2/0.8; normal is about age/4 + 4
Hypoxemia that corrects with oxygen → V/Q mismatch; little correction → shunt (ARDS, consolidation, AV malformation)
Acute respiratory acidosis → HCO3 rises 1 per 10 mmHg PaCO2; chronic → about 4 per 10
Bilateral noncardiac opacities within a week of an insult → ARDS when PaO2/FiO2 ≤300
ARDS ventilation → tidal volume 6 mL/kg predicted body weight, plateau ≤30 cmH2O, PEEP to oxygenate
Moderate-severe ARDS with PaO2/FiO2 under 150 → prone positioning for most of the day (12–16 hours or more)
ARDS once shock resolves → conservative fluids to shorten ventilation
Acute hypoxemic failure without hypercapnia → high-flow nasal cannula over NIV
NIV works best → hypercapnic COPD flare, cardiogenic pulmonary edema, after extubation in high-risk patients
NIV contraindications → unprotected airway, vomiting, facial trauma, cardiac arrest, unstable shock, undrained pneumothorax
Intubate → failing NIV or high-flow, GCS ≤8, airway not protected, worsening acidosis, exhaustion
Ventilated patient suddenly desaturates → check tube displacement, obstruction, pneumothorax, equipment; disconnect and bag
High peak, normal plateau pressure → airway resistance (mucus, bronchospasm, kinked tube); both high → stiff lung or pneumothorax
Every ventilated patient daily → sedation interruption with a spontaneous breathing trial; extubate if passed
Ventilator pneumonia prevention → head of bed 30–45 degrees, daily sedation holiday, oral care
Myasthenia or Guillain-Barre with dyspnea → serial FVC and NIF; intubate if FVC under 20 mL/kg or NIF weaker than −30
Postoperative hypoxemia with basal dullness on days 1–2 → atelectasis; incentive spirometry, early walking
Most acutely ill adults on oxygen → aim SpO2 about 92–96%; 88–92% if CO2 retention risk
Snoring, witnessed apneas, sleepiness, obesity, resistant HTN → screen for OSA, then sleep testing
Suspected moderate-severe OSA without major comorbidity → home sleep apnea test
HF, neuromuscular or lung disease, opioid use, or negative home test → in-lab polysomnography
AHI ≥15, or ≥5 with symptoms or comorbidity → obstructive sleep apnea
OSA → CPAP first; weight loss (tirzepatide is approved), oral appliance or hypoglossal nerve stimulation if CPAP fails
BMI ≥30, awake PaCO2 over 45, no other cause → obesity hypoventilation; PAP therapy and weight loss
HFrEF with central apnea → optimize HF therapy; avoid adaptive servo-ventilation if EF ≤45%
Sleepy driver with untreated OSA → counsel not to drive drowsy until treated

Traps that cost points

Treating opioid-induced hypoventilation with oxygen alone→ The problem is ventilation; oxygen hides rising CO2. Reverse with naloxone or support breathing.
Tidal volume of 10 mL/kg actual body weight in ARDS→ Use predicted body weight from height; large volumes overstretch the lung and raise mortality.
NIV for a vomiting, obtunded patient→ An unprotected airway will aspirate; intubate.
More sedation for a ventilated patient with a sudden pressure spike→ Look first for pneumothorax, plugging or tube problems.
Waiting for hypercapnia before intubating a weakening Guillain-Barre patient→ CO2 rises late in neuromuscular failure; act on falling FVC and NIF.
Adaptive servo-ventilation for central apnea in HFrEF→ It increased mortality when EF was 45% or lower.
Home sleep test in a patient with severe COPD or HF→ Home tests miss hypoventilation and central events; order in-lab polysomnography.
Keeping every ICU patient at 100% saturation→ Hyperoxia offers no benefit and may harm; titrate to a target range.

Upper airway, sinus & throat

In the Brain

Most sore throats, sinus infections and coughs are viral; test and treat by criteria, and treat a lasting neck mass or hoarseness in a smoker as possible cancer.

Rules to know

Sore throat with cough, runny nose or hoarseness → viral; no strep test, no antibiotics
Fever, tonsillar exudate, tender anterior nodes, no cough → rapid strep test; treat only if positive
Negative rapid strep in a child or teen → confirm with throat culture; adults do not need one
Group A strep pharyngitis → penicillin V or amoxicillin for 10 days; cephalexin or azithromycin if allergic
Severe sore throat, muffled voice, trismus, uvula pushed aside → peritonsillar abscess; drain and give antibiotics
Teen with sore throat, posterior nodes, fatigue, splenomegaly → mononucleosis; heterophile test, no contact sports for at least 3–4 weeks
Rash after amoxicillin during mononucleosis → not a true penicillin allergy
Sinus symptoms under 10 days and improving → viral; saline, analgesics, intranasal steroid
Bacterial sinusitis criteria → ≥10 days without improvement, 3–4 days of high fever with purulence, or worsening after improving
Acute bacterial sinusitis in an adult → amoxicillin with or without clavulanate 5–7 days, or watchful waiting with assured follow-up
Sinusitis with eyelid swelling, vision change or severe headache → contrast CT, IV antibiotics, urgent ENT
DKA or neutropenia with black nasal eschar → mucormycosis; surgical debridement plus amphotericin B
Acute bronchitis, cough under 3 weeks, normal vitals and lung exam → no antibiotics; cough may last 3 weeks
Influenza in a high-risk outpatient (65 or older, pregnant, chronic disease) → oseltamivir, ideally within 48 hours
Hospitalized with influenza → oseltamivir however long symptoms have lasted
Chronic cough over 8 weeks, nonsmoker, normal chest x-ray → postnasal drip, asthma, reflux; stop ACE inhibitor, treat stepwise
Seasonal sneezing, itchy eyes, pale boggy turbinates → allergic rhinitis; intranasal corticosteroid first-line
Anterior nosebleed → lean forward, firm pressure on the soft nose 10–15 minutes; then vasoconstrictor, cautery or packing
Bleeding despite anterior packing, or posterior source → posterior balloon or pack, admit, ENT
Recurrent nosebleeds with lip and finger telangiectasias → hereditary hemorrhagic telangiectasia; screen for lung and brain AVMs
Hoarseness lasting 4 weeks, or sooner with smoking or neck mass → laryngoscopy
Adult neck mass ≥2 weeks without infection → contrast CT and fine-needle aspiration; no empiric antibiotics
Head and neck squamous cancer → tobacco and alcohol; oropharyngeal tumors in nonsmokers are often HPV-related
Adult with a new one-sided middle ear effusion → examine the nasopharynx for carcinoma
Child with fever, drooling, neck stiffness, widened prevertebral space → retropharyngeal abscess; contrast CT, IV antibiotics, drainage
Nasal septal perforation → cocaine use, granulomatosis with polyangiitis, trauma or prior surgery

Traps that cost points

Antibiotics for sore throat with cough and coryza→ Viral features predict a negative strep test; antibiotics add rash, diarrhea and resistance.
Throat culture after a negative rapid test in an adult→ Adult strep is less common and rheumatic fever rare; culture backup is for children and teens.
Antibiotics on day 5 of a sinus infection→ Most early sinusitis is viral; treat only once bacterial criteria are met.
Sinus CT for uncomplicated acute sinusitis→ Imaging cannot separate viral from bacterial disease; keep it for complications or surgical planning.
Withholding oseltamivir from an inpatient on day 4 of illness→ Hospitalized patients benefit even after 48 hours; treat.
Repeated antibiotic courses for a persistent neck mass in a smoker→ An adult neck mass without infection is cancer until proven otherwise; image and aspirate.
Labeling a mononucleosis patient penicillin-allergic after an amoxicillin rash→ The rash reflects the viral illness; avoid a lifelong mislabel.
Tilting the head back for a nosebleed→ Blood runs into the throat and stomach; lean forward and compress the soft nose.

Pediatric airway & lung disease

In the Brain

Steroids for croup, supportive care for bronchiolitis, the operating room for epiglottitis, bronchoscopy for a convincing foreign-body story, and a sweat test when growth and lungs both fail.

Rules to know

Barking cough and stridor after a cold, age 6 months–3 years → croup; single oral dose of dexamethasone
Croup with stridor at rest → nebulized racemic epinephrine plus dexamethasone; observe 2–4 hours after epinephrine
Croup diagnosis → clinical; neck film only if the diagnosis is unclear
Toxic, drooling, tripod position, muffled voice, high fever, incomplete vaccination → epiglottitis; secure the airway in the OR, then IV ceftriaxone
Croup-like illness then high fever, toxicity, poor epinephrine response → bacterial tracheitis; airway, vancomycin plus ceftriaxone
Infant whose cold progresses to wheeze, crackles and retractions → bronchiolitis; suction, fluids, oxygen if SpO2 under 90%
Bronchiolitis → no routine albuterol, steroids, antibiotics, chest x-ray or viral testing
Bronchiolitis admission → hypoxemia, poor feeding or dehydration, apnea, marked distress, very young or premature infant
RSV prevention → nirsevimab or clesrovimab before the first season unless the mother had RSV vaccine ≥14 days before birth
Toddler with sudden choking, then cough and one-sided wheeze → foreign body; rigid bronchoscopy
Suspected aspirated object with a normal film → expiratory or decubitus films show air trapping; bronchoscopy if history is strong
Choking infant who cannot cry → 5 back blows then 5 chest thrusts, repeat; no blind finger sweeps
Infant with coughing fits, whoop or apnea, post-tussive vomiting → pertussis; azithromycin at any age
Household contacts of pertussis → azithromycin prophylaxis whatever their vaccine status
Recurrent pneumonia, poor growth, greasy stools or nasal polyps → cystic fibrosis; sweat chloride ≥60 confirms
Abnormal CF newborn screen → sweat chloride test
CF care → airway clearance, dornase alfa, hypertonic saline, pancreatic enzymes, fat-soluble vitamins, CFTR modulator by genotype
CF with first Pseudomonas growth → inhaled tobramycin to eradicate
Recurrent sinusitis, otitis and bronchiectasis with situs inversus → primary ciliary dyskinesia
Apnea of prematurity → caffeine; usually resolves by about 37 weeks postmenstrual age; home monitors do not prevent SIDS
Well infant over 60 days, brief event under 1 minute, normal exam → low-risk BRUE; education, CPR teaching, no admission
Polyhydramnios, frothy drooling, choking at first feed, tube coils in chest → esophageal atresia with TE fistula
Distress at birth, scaphoid abdomen, bowel in chest → diaphragmatic hernia; intubate, no bag-mask, gastric decompression
Stridor worse supine and with feeds, better prone, thriving infant → laryngomalacia; reassure, resolves by about 18 months
Preterm infant still needing oxygen at 36 weeks postmenstrual age → bronchopulmonary dysplasia; RSV prevention, growth and PH monitoring
Recurrent pneumonia in the same lobe → foreign body, sequestration or congenital malformation; CT chest

Traps that cost points

Neck x-ray to diagnose typical croup→ Croup is clinical; imaging delays treatment and adds radiation.
Examining the throat with a tongue blade in suspected epiglottitis→ Agitation can trigger complete obstruction; keep the child calm and secure the airway in the OR.
Albuterol and steroids for bronchiolitis→ Neither changes the course; supportive care is the treatment.
Ruling out a foreign body because the chest x-ray is normal→ Most aspirated objects are radiolucent; a convincing history warrants bronchoscopy.
Erythromycin for pertussis in a 3-week-old→ Erythromycin is linked to pyloric stenosis in young infants; use azithromycin.
Abdominal thrusts for a choking 8-month-old→ Under 1 year use back blows and chest thrusts; abdominal thrusts can injure the liver.
Admitting a well, low-risk BRUE infant for extensive tests→ Low-risk events rarely signal disease; educate, teach CPR and arrange follow-up.
Bag-mask ventilation at birth for a suspected diaphragmatic hernia→ Air inflates the bowel in the chest and compresses the lung; intubate directly.