NBME CBSE Question and Answer (2026)
| Newest Update Verified Answers with
Detailed Rationales | A+ Verified
• Neonatal Respiratory Distress:
Etiology + Tx -✓✓Maternal DM (*high insulin*)
or C-section (*low cortisol*)
TX: *dexamethasone* before birth
• Lung maturity determined with -✓✓Amniocentesis of Phospholipids (*type II
pneumocytes)
L >> S
• Type I pneumocytes -✓✓Squamous gas diffusion
• Elastase in lungs -✓✓macrophage: *lysosomes*
PMN: *azuronphilic granules*
• Elastin stretches and recoils due to -✓✓Lysine interchain crosslinks
• air pressure and
intrapleural pressure at FRC -✓✓Air pressure = 0
Intrapleural pressure = -5
• Pulm Vasc Resistance is lowest during -✓✓Exhale of Tidal Volume
• Lung Compliance is decreased by -✓✓LHF, pulmonary edema,
pulmonary fibrosis
• Lung Compliance is increased by -✓✓emphysema, age
• Obesity affects ERV and FRC -✓✓DECREASE
ERV & FRC
• Blood flow/min (pulmonary v systemic) -✓✓pulmonary = systemic
• Anatomic pulmonary shunting -✓✓Bronchial circulation causes
*decreased PO2 in LA/LV*
than in pulmonary capillaries
• More ventilation is at the -✓✓BASE
,• O2-Hgb dissociation LEFT shift -✓✓basic, cold, low 2,3 BPG
low pO2 (compensatory erythrocytosis)
• O2-Hgb dissociation RIGHT shift -✓✓low pH, high 2,3BPG, high T
HOT, ACIDIC
• CO2 transport to lungs -✓✓*carbonic anhydrase*
Cl shift
*Haldane*: CO2 released to lung
(*Bohr*: O2 release to tissue)
• CO poisoning causes -✓✓carboxyhemoglobin
no affect on PaO2
• Cyanide poisoning causes -✓✓lactic acidosis
• How to treat cyanide poisoning -✓✓*Amyl nitrite* --> Methemoglobin
THEN *Thiosulfate* (hydroxycobalamin)
• Normal A-a gradient -✓✓5-15
Hypoventilation: Heroin OD or high altitude
• Increased A-a gradient -✓✓*Diffusion impairment* (fibrosis)
*R-L shunt* (aspiration, ARDS)
*V/Q mismatch* (pulmonary edema
• AT --> AT II
where and how -✓✓ACE
(- high in sarcoidosis)
In small pulmonary bV
• C5a induces what -✓✓PMN influx (ie: in lungs)
• Korotkoff sound -✓✓BP cuff - appear and disappear
in inflation/deflation
• Pulsus Paradoxus -✓✓10mmHg difference in
Korotkoff sound
• Pulsus Paradoxus occurs in -✓✓Cardiac Tamponade
• Kussmaul sign -✓✓JVP rises *during inspiration*
Constrictive Pericardiditis
,• Restrictive/Interstitial Lung Disease:
A-a, FVC, FEV1, EFR -✓✓Airway widening due to *radial traction* from fibrosis
*increase Aa*
decreased FVC & FEV1
*Increased EFR*
• Sarcoidosis -✓✓*Th1 *noncaseating granulmona
bilateral hilar adenopathy
increased *ACE*
increased IL2, IFNg
1-a-hydroxylase in macrophages: vit D --> *HyperCa*
• Hyper Ca causes -✓✓stones, thrones, groans, psych overtones
• 1-a-hydroxylase in macrophages -✓✓PTH independent conversion of
Calcifediol to *calcitriol* (bioactive Vit D)
Vit D --> Hyper Ca
• Idiopathic pulmonary fibrosis -✓✓*Honeycomb* pattern
loss of Type 1 pneumocytes
*hyperplasia Type II* pneumocytes
• Goodpasture -✓✓HS II
Auto-Ab against BM destroys lung alveoli (*restrictive*) and renal glomeruli
• Obstructive Lung Disease -✓✓DECREASED FEV1, Decreased FVC
increased RV, FRC, TLC
**different shape
• COPD -✓✓PMN, mo, CD8
*V/Q mismatch:* O2 induced hypercapnia;
physio dead space
• Myeloperoxidase causes -✓✓Green sputum/pus
• Do not give O2 supplement to -✓✓COPD patient
Decreased stimulation of
*carotid bodies* = decreased RR
• TX COPD with -✓✓*Fluticasone* (glucocorticoid)
inhibit cellular reaction
, • a1-antitrypsin deficiency -✓✓Serine protease inhibitor
*LIVER*
*LUNG*: inc PMN elastase --> emphysema
• Asthma dx -✓✓*Methacholine* (maCh) challenge
= induce bronchoconstriction
to reduce FEV1
+ test = Airways ARE reactive
• B2 agonist MOA -✓✓B2 (Gs) --> AC --> increase *cAMP*
• Corticosteroid MOA -✓✓inhibit cytokine synthesis
suppress T lymphocyte
• mACh Antagonist ("tropium") MOA -✓✓*inhibit Vagal* via ACh
--> decreased Ca
• OSA causes -✓✓pulmonary HTN and RHF
increases EPO which worsens HTN
• EPO can do what
on Cardiovascular -✓✓worsen HTN
• Pulmonary Arterial HTN -✓✓*BMPR2*
High *endothelin*, Low NO
SMC hypertophy, fibrosis, narrow lumen
*P2 louder* than A2
• When is P2 louder than A2 -✓✓Pulmonary Artherial Hypertension
• TX pulmonary arterial hypertension -✓✓Endothelin-R antagonist:
- Bo*sentan*, Ambi*sentan*
PGEi (inc cGMP):
- Silden*afil*
• Pulmonary Embolism -✓✓*perfusion defect* (V/Q mismatch)
sudden SOB + calf swelling
Hypoxemia --> *Hyperventilate *
--> *Respiratory Alkalosis *
--> Metabolic compensation in 2 days
• dx pulmonary embolism -✓✓*D-dimer* test
CT angiogram
Lines of Zahn
| Newest Update Verified Answers with
Detailed Rationales | A+ Verified
• Neonatal Respiratory Distress:
Etiology + Tx -✓✓Maternal DM (*high insulin*)
or C-section (*low cortisol*)
TX: *dexamethasone* before birth
• Lung maturity determined with -✓✓Amniocentesis of Phospholipids (*type II
pneumocytes)
L >> S
• Type I pneumocytes -✓✓Squamous gas diffusion
• Elastase in lungs -✓✓macrophage: *lysosomes*
PMN: *azuronphilic granules*
• Elastin stretches and recoils due to -✓✓Lysine interchain crosslinks
• air pressure and
intrapleural pressure at FRC -✓✓Air pressure = 0
Intrapleural pressure = -5
• Pulm Vasc Resistance is lowest during -✓✓Exhale of Tidal Volume
• Lung Compliance is decreased by -✓✓LHF, pulmonary edema,
pulmonary fibrosis
• Lung Compliance is increased by -✓✓emphysema, age
• Obesity affects ERV and FRC -✓✓DECREASE
ERV & FRC
• Blood flow/min (pulmonary v systemic) -✓✓pulmonary = systemic
• Anatomic pulmonary shunting -✓✓Bronchial circulation causes
*decreased PO2 in LA/LV*
than in pulmonary capillaries
• More ventilation is at the -✓✓BASE
,• O2-Hgb dissociation LEFT shift -✓✓basic, cold, low 2,3 BPG
low pO2 (compensatory erythrocytosis)
• O2-Hgb dissociation RIGHT shift -✓✓low pH, high 2,3BPG, high T
HOT, ACIDIC
• CO2 transport to lungs -✓✓*carbonic anhydrase*
Cl shift
*Haldane*: CO2 released to lung
(*Bohr*: O2 release to tissue)
• CO poisoning causes -✓✓carboxyhemoglobin
no affect on PaO2
• Cyanide poisoning causes -✓✓lactic acidosis
• How to treat cyanide poisoning -✓✓*Amyl nitrite* --> Methemoglobin
THEN *Thiosulfate* (hydroxycobalamin)
• Normal A-a gradient -✓✓5-15
Hypoventilation: Heroin OD or high altitude
• Increased A-a gradient -✓✓*Diffusion impairment* (fibrosis)
*R-L shunt* (aspiration, ARDS)
*V/Q mismatch* (pulmonary edema
• AT --> AT II
where and how -✓✓ACE
(- high in sarcoidosis)
In small pulmonary bV
• C5a induces what -✓✓PMN influx (ie: in lungs)
• Korotkoff sound -✓✓BP cuff - appear and disappear
in inflation/deflation
• Pulsus Paradoxus -✓✓10mmHg difference in
Korotkoff sound
• Pulsus Paradoxus occurs in -✓✓Cardiac Tamponade
• Kussmaul sign -✓✓JVP rises *during inspiration*
Constrictive Pericardiditis
,• Restrictive/Interstitial Lung Disease:
A-a, FVC, FEV1, EFR -✓✓Airway widening due to *radial traction* from fibrosis
*increase Aa*
decreased FVC & FEV1
*Increased EFR*
• Sarcoidosis -✓✓*Th1 *noncaseating granulmona
bilateral hilar adenopathy
increased *ACE*
increased IL2, IFNg
1-a-hydroxylase in macrophages: vit D --> *HyperCa*
• Hyper Ca causes -✓✓stones, thrones, groans, psych overtones
• 1-a-hydroxylase in macrophages -✓✓PTH independent conversion of
Calcifediol to *calcitriol* (bioactive Vit D)
Vit D --> Hyper Ca
• Idiopathic pulmonary fibrosis -✓✓*Honeycomb* pattern
loss of Type 1 pneumocytes
*hyperplasia Type II* pneumocytes
• Goodpasture -✓✓HS II
Auto-Ab against BM destroys lung alveoli (*restrictive*) and renal glomeruli
• Obstructive Lung Disease -✓✓DECREASED FEV1, Decreased FVC
increased RV, FRC, TLC
**different shape
• COPD -✓✓PMN, mo, CD8
*V/Q mismatch:* O2 induced hypercapnia;
physio dead space
• Myeloperoxidase causes -✓✓Green sputum/pus
• Do not give O2 supplement to -✓✓COPD patient
Decreased stimulation of
*carotid bodies* = decreased RR
• TX COPD with -✓✓*Fluticasone* (glucocorticoid)
inhibit cellular reaction
, • a1-antitrypsin deficiency -✓✓Serine protease inhibitor
*LIVER*
*LUNG*: inc PMN elastase --> emphysema
• Asthma dx -✓✓*Methacholine* (maCh) challenge
= induce bronchoconstriction
to reduce FEV1
+ test = Airways ARE reactive
• B2 agonist MOA -✓✓B2 (Gs) --> AC --> increase *cAMP*
• Corticosteroid MOA -✓✓inhibit cytokine synthesis
suppress T lymphocyte
• mACh Antagonist ("tropium") MOA -✓✓*inhibit Vagal* via ACh
--> decreased Ca
• OSA causes -✓✓pulmonary HTN and RHF
increases EPO which worsens HTN
• EPO can do what
on Cardiovascular -✓✓worsen HTN
• Pulmonary Arterial HTN -✓✓*BMPR2*
High *endothelin*, Low NO
SMC hypertophy, fibrosis, narrow lumen
*P2 louder* than A2
• When is P2 louder than A2 -✓✓Pulmonary Artherial Hypertension
• TX pulmonary arterial hypertension -✓✓Endothelin-R antagonist:
- Bo*sentan*, Ambi*sentan*
PGEi (inc cGMP):
- Silden*afil*
• Pulmonary Embolism -✓✓*perfusion defect* (V/Q mismatch)
sudden SOB + calf swelling
Hypoxemia --> *Hyperventilate *
--> *Respiratory Alkalosis *
--> Metabolic compensation in 2 days
• dx pulmonary embolism -✓✓*D-dimer* test
CT angiogram
Lines of Zahn
