Pneumologia SBPT common mistakes
Pneumologia SBPT · Understand the traps and how to avoid them.
On a spirometry question, the candidate labels a post-bronchodilator FEV1/FVC ratio below the fixed cutoff as irreversible obstruction without first confirming that the ratio was calculated from post-bronchodilator values and that the FVC maneuver met acceptability criteria.
Candidates memorize the fixed 0.70 ratio but rush the sequence: they compare pre-bronchodilator numbers, or accept a truncated FVC effort, and then jump to 'fixed obstruction' or 'DPOC' before checking bronchodilator response (an FEV1 or FVC gain of 200 mL and 12%).
What to do instead
Adopt a fixed reading order for every spirometry stem: (1) confirm acceptability/reproducibility, (2) read pre-bronchodilator FEV1/FVC, (3) read post-bronchodilator FEV1/FVC, (4) quantify the absolute and percent change, (5) only then classify. Write the four numbers down before choosing an option.
The candidate manages an acute asthma exacerbation in the emergency setting by ordering a chest radiograph and arterial blood gas routinely before starting inhaled short-acting beta-agonist therapy, and delays treatment until results return.
Hospital-based training habits and fear of missing pneumothorax or a mimic lead candidates to over-investigate; exam stems reward immediate bronchodilation and early systemic corticosteroid, with imaging and blood gas reserved for suspected complications, poor response, or impending respiratory failure.
What to do instead
Memorize the order of priorities: SABA by metered-dose inhaler with spacer or nebulizer, early systemic corticosteroid, oxygen to target saturation, then reassess. Reserve chest radiograph and blood gas for non-response, suspected pneumothorax/consolidation, or signs of fatigue and hypercapnia.
When a stem describes a patient with COPD and a raised blood eosinophil count, the candidate automatically adds an inhaled corticosteroid to the bronchodilator regimen regardless of exacerbation history, or conversely denies inhaled corticosteroid to a frequent exacerbator with elevated eosinophils.
Candidates treat eosinophils as a stand-alone switch rather than one factor in a risk-based decision; they forget that inhaled corticosteroid benefit is concentrated in patients with prior exacerbations and higher eosinophil counts, and that pneumonia risk and asthma overlap modify the choice.
What to do instead
Use a two-axis framework: exacerbation risk (number and severity in the past year) on one axis, eosinophil count and asthma features on the other. State explicitly in your reasoning when inhaled corticosteroid is indicated (recurrent exacerbations with elevated eosinophils, or asthma-COPD overlap) and when it should be avoided or de-escalated.
For a suspected pulmonary tuberculosis case, the candidate selects a diagnostic test without matching it to the clinical scenario, for example requesting only sputum smear microscopy in a patient with suspected extrapulmonary or smear-negative disease, or ordering an interferon-gamma release assay to diagnose active disease.
Candidates conflate tests for latent infection with tests for active disease, and forget that sensitivity of smear microscopy is modest and lower in extrapulmonary and HIV-coinfected patients; they also overlook that rapid molecular testing is the preferred initial test where available.
What to do instead
Build a decision table: rapid molecular assay as the initial test on respiratory specimens when active pulmonary disease is suspected; smear and culture for monitoring and drug susceptibility; interferon-gamma release assay or tuberculin skin test only for latent infection, never to rule in active disease. For extrapulmonary disease, specify the specimen (pleural fluid, lymph node, cerebrospinal fluid) and pair molecular testing with culture.
The candidate stages a lung cancer with a single imaging modality and then declares a treatment plan, without integrating mediastinal nodal assessment and distant staging, and without confirming tissue diagnosis and histologic subtype before discussing targeted therapy.
Stems present imaging findings in narrative form, and candidates stop at tumor size or a solitary nodule, forgetting that stage determines whether surgery, chemoradiation, or systemic therapy applies, and that molecular profiling (for example epidermal growth factor receptor, anaplastic lymphoma kinase, programmed death-ligand 1) is required before targeted or immunotherapy choices.
What to do instead
Use a fixed staging checklist: tumor size and local invasion, nodal stations (with the appropriate mediastinal sampling procedure), and distant disease including brain imaging in appropriate candidates. Then require tissue confirmation plus subtype and molecular markers before selecting systemic therapy. Write the TNM group before the treatment option.
The candidate classifies severity of a COPD exacerbation or of community-acquired pneumonia using a single abnormal value (for example oxygen saturation or respiratory rate) and ignores the composite scoring and the presence of acid-base disturbance or comorbid decompensation.
Candidates anchor on the most visually striking number in the stem and do not systematically apply severity criteria; they also forget that decision to admit or to escalate to ventilatory support depends on combined criteria and on trajectory rather than one measurement.
What to do instead
Before answering, list every severity criterion present in the stem in a column and count them. For pneumonia, apply a validated severity score and check for major criteria for intensive care. For exacerbation, document pH, carbon dioxide, oxygen saturation, work of breathing, and comorbidity, then state the disposition that follows.
The candidate interprets a pleural effusion without applying Light's criteria, or applies them but misclassifies a transudate as exudate because a single ratio was borderline, and then proceeds to the wrong management pathway.
Candidates remember the three criteria but not the logic that any single positive criterion makes the fluid an exudate, and they forget the exceptions (diuretic-treated heart failure, parapneumonic effusion) that require clinical correlation or additional testing.
What to do instead
Compute all three ratios explicitly: pleural protein to serum protein, pleural lactate dehydrogenase to serum lactate dehydrogenase, and pleural lactate dehydrogenase against the upper limit of normal for serum. Classify as exudate if any one is met, then immediately check the clinical context for a misleading result and state the next step (for example imaging, cytology, or drainage) rather than stopping at the label.
The candidate answers a question about long-term oxygen therapy or non-invasive ventilation by quoting the indication threshold but not the qualifying conditions: they recommend oxygen for a patient who is not stable or not optimally treated, or recommend non-invasive ventilation in a patient with a contraindication.
Thresholds are memorized in isolation from the prerequisites (clinical stability, two measurements, optimal medical therapy) and from contraindications (inability to protect the airway, severe encephalopathy, facial trauma, hemodynamic instability), so the candidate picks the right number in the wrong patient.
What to do instead
For every oxygen or ventilation question, verify eligibility before the threshold: stability and repeat measurement for long-term oxygen, and airway protection, consciousness, hemodynamics, and mask fit for non-invasive ventilation. State the contraindication check out loud in your reasoning before selecting an option.
The candidate answers a tuberculosis treatment question by naming the standard regimen but omits the duration, the intensive versus continuation phase, and the directly observed therapy and drug-susceptibility caveats, or applies the standard regimen to a patient with prior treatment or suspected resistance.
Regimens are learned as drug lists rather than as time-structured plans; candidates also skip the history of previous treatment and contact with resistant cases, which changes the regimen and the need for susceptibility testing.
What to do instead
Always write the regimen as phase, drugs, dose frequency, and total duration, then check three modifiers: prior treatment, known contact with resistant disease, and special situations (pregnancy, liver disease, HIV coinfection). If any modifier is present, state that susceptibility testing guides the regimen before naming drugs.
The candidate interprets a blood gas in a patient with an acute asthma or COPD exacerbation by reading only the partial pressure of oxygen and pH, ignoring that a 'normal' or rising carbon dioxide in a tiring asthma patient signals impending respiratory failure, and ignores the expected compensatory pattern.
Candidates expect hypercapnia to be the marker of severe COPD and therefore under-read the same value in asthma, where a normal carbon dioxide during a severe attack is an ominous sign; they also skip the calculation of expected compensation and the anion gap.
What to do instead
For every blood gas, read in a fixed sequence: oxygenation and alveolar-arterial gradient, pH, carbon dioxide, bicarbonate, expected compensation, and anion gap. In asthma, explicitly flag any carbon dioxide that is normal or rising as a warning sign requiring urgent reassessment and preparation for ventilatory support.