11.1 Respiratory Diagnosis

The current FNP-BC Test Content Outline scores Respiratory as one of the 13 body systems and asks you to select diagnostics, interpret them, and formulate differentials (Domain II). Implementation later tests what you prescribe. This section is the diagnostic chapter: name the disease correctly before you reach for an inhaler or an antibiotic.

Asthma versus COPD versus overlap

Asthma is a heterogeneous disease of variable respiratory symptoms — wheeze, shortness of breath, chest tightness, cough — that vary over time and intensity, plus confirmed variable expiratory airflow limitation. GINA is explicit: symptoms alone are not a diagnosis. Confirm variability with spirometry (bronchodilator reversibility is the usual first test), excessive peak-expiratory-flow variability, a clear response after controller therapy, or, when needed, a challenge test arranged with specialty care. Atopy, childhood onset, night or early-morning symptoms, and triggers (exercise, allergen, viral colds, NSAIDs in aspirin-exacerbated disease) support asthma. Normal spirometry on a good day does not exclude asthma; it means you still owe the patient a demonstration of variability.

COPD is persistent respiratory symptoms and airflow obstruction caused by airway and/or alveolar abnormalities, usually after significant exposure to noxious particles or gases — most often tobacco, but also biomass smoke and occupational dusts. GOLD confirms obstruction with post-bronchodilator FEV1/FVC <0.70. Compatible symptoms are progressive dyspnea, chronic cough, sputum, and recurrent lower-respiratory infections. GOLD 1–4 grades severity by post-bronchodilator FEV1 percent predicted (≥80%, 50–79%, 30–49%, <30%). Treatment grouping is ABE: symptom burden (mMRC or CAT) plus exacerbation history. Group E is frequent moderate exacerbations or any hospitalization — that label is about risk, not about a different spirometric ratio.

Asthma–COPD overlap (sometimes called ACO) is a descriptive label, not a single disease with its own code you must force. The patient has persistent post-bronchodilator obstruction and features of asthma — large reversibility, childhood asthma, atopy, or highly variable symptoms — often on a smoking background. The FNP trap is treating that person like “just COPD” with a long-acting bronchodilator alone. The asthma component means the regimen must include an inhaled corticosteroid. Uncertain or severe overlap belongs with pulmonary medicine; do not spend months escalating LAMA monotherapy while the eosinophilic, steroid-responsive half of the disease is untreated.

Peak flow versus spirometry

Spirometry is the diagnostic test. You need a full forced vital capacity maneuver, acceptable and repeatable curves, and — when obstruction is the question — pre- and post-bronchodilator values. FEV1/FVC defines obstruction. FEV1 percent predicted stages COPD. A significant bronchodilator response (classically an FEV1 increase of at least 12% and 200 mL) supports asthma or an asthma component; its absence does not prove COPD if the history is wrong. Restriction is only suggested by a low FVC with a normal or high ratio; you need lung volumes before you label interstitial or neuromuscular disease. Do not “diagnose COPD” from a peak-flow number.

Peak expiratory flow is a monitoring tool for people who already have an asthma diagnosis. It is effort-dependent, device-dependent, and too crude to confirm COPD or to sort restriction from obstruction. Use it to build an action plan off the patient’s personal best (green / yellow / red zones), to document variability when spirometry is pending, and to coach a known asthmatic through a viral week. A single low peak flow in the office is a data point, not a disease name. If the question is “does this adult have obstruction?”, order spirometry.

Pneumonia versus acute bronchitis versus COVID, influenza, and RSV

Acute bronchitis is a self-limited lower-airway inflammation, almost always viral, with cough lasting one to three weeks. The lung exam is typically diffuse or normal; vital signs are near normal; oxygenation is preserved. Chest radiograph is not routine when you have no focal findings, no hypoxia, no hemoptysis, and no systemic red flags. Antibiotics do not shorten typical viral bronchitis and they do create resistance and adverse effects. Call it what it is and treat symptoms, then reconsider if the course breaks the usual pattern.

Community-acquired pneumonia (CAP) is infection of the pulmonary parenchyma. Suspect it when cough travels with fever, pleuritic pain, dyspnea, tachypnea, hypoxia, or focal crackles, egophony, or dullness. A chest radiograph (or other imaging) that shows a new infiltrate supports the diagnosis and helps you avoid treating “bronchitis” that is actually lobar pneumonia. Site-of-care is the first decision: hypoxia, hypotension, confusion, respiratory rate in the 30s, inability to take oral therapy, or a frail older adult who cannot maintain hydration belongs in the emergency department, not on a five-day office antibiotic with a “call if worse” plan. CURB-65 and pneumonia-severity tools are aides, not a substitute for looking at the patient.

Influenza, COVID-19, and RSV overlap clinically. Test when the result changes management — antiviral eligibility, isolation, cohorting, or a different workup — especially in pregnancy, older adults, cardiopulmonary disease, and infants. Influenza in primary care is a timed antiviral decision (Section 11.2). RSV is most dangerous at the extremes of age. Do not invent a unique 2026 COVID protocol on the exam; treat testing as a decision tool and follow current CDC/IDSA outpatient antiviral criteria for high-risk COVID.

Pertussis and the prolonged cough

Immunized adolescents and adults still get Bordetella pertussis, and they present as a prolonged paroxysmal cough, often without the childhood whoop. Post-tussive vomiting, inspiratory whoop, or a cough that has already lasted two weeks with paroxysms should make you swab, not just add another inhaler. Nasopharyngeal PCR is most useful early; later in the course, clinical diagnosis plus public-health reporting still matters. Pertussis is reportable. Treat the index case (a macrolide is the usual class; follow current CDC dosing) and offer chemoprophylaxis to close contacts. Pregnancy Tdap each pregnancy is prevention, not a diagnostic test. The exam trap is calling every six-week post-viral cough “bronchitis” and missing a household outbreak.

Tuberculosis: who to test

Do not screen the entire waiting room. Test people at increased risk of infection or increased risk of progression: recent close contact, immigration from a high-prevalence region, incarceration or homelessness, healthcare exposure, HIV, TNF-inhibitor or other immunosuppression, silicosis, and some other high-risk medical conditions. IGRA (interferon-gamma release assay) is preferred in BCG-vaccinated people and in those unlikely to return for TST reading. TST cutoffs remain risk-stratified (5 mm in HIV, close contacts, and the immunosuppressed; 10 mm in recent immigrants, congregate settings, and healthcare workers; 15 mm when risk is low). A positive screen for latent infection is not a reason to start four-drug therapy in the hallway. Active TB — prolonged cough, night sweats, weight loss, hemoptysis, upper-lobe infiltrate — means isolation, NAAT/AFB, public-health notification, and specialty treatment. The FNP’s job is recognition and the right test, not improvising RIPE from memory.

OSA, PE, and lung-cancer red flags

Obstructive sleep apnea is a history diagnosis you then confirm with a sleep study. Use STOP-BANG conceptually: Snoring, daytime Tiredness, Observed apneas, high blood Pressure, BMI in the obesity range, Age over 50, large Neck, male Gender. Intermediate or high scores, resistant hypertension, atrial fibrillation, and marked somnolence all justify referral — not a stimulant for “fatigue.” Overnight oximetry can support suspicion; it does not replace a diagnostic sleep study when pretest probability is high.

Pulmonary embolism is an emergency differential, not an antibiotic-failure diagnosis. Red flags: sudden dyspnea, pleuritic pain, hemoptysis, unexplained tachycardia or hypoxia, syncope, and unilateral leg swelling or a known clot risk (surgery, cancer, estrogen, prior VTE, pregnancy). Wells and PERC help you think; they do not let you observe a hypotensive, hypoxic patient in clinic. Send unstable or high-probability patients to the emergency department for definitive imaging. Do not start a DOAC from the exam room on a hunch.

Lung cancer red flags in primary care: hemoptysis, unexplained weight loss, a new or changing cough in a person who smokes, persistent hoarseness, clubbing, recurrent pneumonia in the same lobe, or a non-resolving infiltrate. Order a chest radiograph now and escalate to CT and urgent pulmonary or oncology referral when the film or the story is wrong. Peak-flow diaries and “seasonal allergies” are not an acceptable delay. Separate from the symptomatic workup, USPSTF supports low-dose CT screening in adults aged 50–80 years with a 20 pack-year history who currently smoke or quit within 15 years — that is screening, not the workup of hemoptysis.

When a chest radiograph is indicated

Order CXR for suspected pneumonia, hemoptysis, suspected tuberculosis, unexplained weight loss with cough, hypoxia or focal findings, failed outpatient therapy, a toxic or older adult with fever and respiratory symptoms, and suspected foreign body or malignancy. Do not order it routinely for typical acute bronchitis or isolated viral upper-respiratory infection with a normal exam. A normal film does not exclude early PE, early pneumonia in a dehydrated patient, or asthma. A bad story plus a normal film means a different test, not reassurance by default.

FNP traps: treating every wheeze as asthma without airflow confirmation; labeling COPD from a smoking history without post-bronchodilator spirometry; giving azithromycin for three weeks of cough and missing pertussis; sending a PE home as “costochondritis”; and watching hemoptysis for a month because “peak flow was 80%.” Diagnosis first, then the respiratory drug class in Section 11.2.