ABIM Pulmonary key terms

The fraction of the forced vital capacity exhaled in the first second. A post-bronchodilator value below 0.70 in adults defines airflow obstruction and is the spirometric cornerstone of COPD diagnosis.

Retention of excess gas in the lungs at end-expiration, reflected by a residual volume above predicted or by a concave expiratory flow-volume curve. It causes hyperinflation and worsens dyspnea during exertion in obstructive disease.

An acute worsening of dyspnea, cough, or sputum beyond usual day-to-day variation that requires additional therapy. Triggers include respiratory infection and air pollution; treatment centers on short-acting bronchodilators, systemic corticosteroids, and antibiotics when indicated.

A bronchial provocation test in which an inhaled cholinergic agonist is given in escalating doses while FEV1 is measured. A fall of 20 percent or more supports airway hyperresponsiveness and helps diagnose asthma when baseline spirometry is normal.

An inherited disorder producing low or dysfunctional antiprotease, leading to early panlobular emphysema that is often basilar, and sometimes to liver disease. Serum level screening and genotyping are indicated in young patients or basilar-predominant COPD.

A histologic and radiologic pattern of patchy fibrosis with fibroblastic foci and honeycombing, typically peripheral and basilar with little ground-glass opacity. It is the hallmark pattern of idiopathic pulmonary fibrosis and carries a poor prognosis.

Clustered thick-walled cystic airspaces in subpleural, basilar lung regions that share walls and represent destroyed, fibrotic lung. It is a key high-resolution CT feature of usual interstitial pneumonia and usually indicates advanced disease.

An immune-mediated interstitial lung disease caused by repeated inhalation of organic antigens, presenting acutely with ground-glass opacities or chronically with fibrosis. Diagnosis rests on exposure history, imaging pattern, bronchoalveolar lavage lymphocytosis, and sometimes antigen testing.

A multisystem granulomatous disease of unknown cause that frequently involves the lungs and intrathoracic lymph nodes. Imaging often shows bilateral hilar adenopathy with perilymphatic nodules, and corticosteroids are used when organ function is threatened.

The single-breath diffusing capacity estimates gas transfer across the alveolar-capillary membrane. It is reduced in emphysema, interstitial lung disease, pulmonary vascular disease, and anemia, and helps interpret restrictive and obstructive physiology.

Pulmonary hypertension caused by intrinsic small-vessel disease, including idiopathic, heritable, drug-related, and connective-tissue-associated forms. It is precapillary, with elevated pulmonary vascular resistance and a normal pulmonary capillary wedge pressure.

Precapillary pulmonary hypertension persisting after organized thromboembolic obstruction of pulmonary arteries. It is the only pulmonary hypertension group treated with potentially curative surgery, so ventilation-perfusion scanning is mandatory during evaluation.

Invasive measurement of right atrial, pulmonary artery, and pulmonary capillary wedge pressures together with cardiac output. It distinguishes precapillary from postcapillary pulmonary hypertension and is required before starting pulmonary vasodilator therapy.

A nuclear imaging study comparing inhaled tracer distribution with intravenously injected particle perfusion. Mismatched segmental defects suggest pulmonary embolism, and a normal or very low probability result effectively excludes it in appropriate patients.

Acute hypoxemic respiratory failure with bilateral opacities not fully explained by cardiac failure, occurring within a week of a known insult. The Berlin definition grades severity by the PaO2/FiO2 ratio measured on positive end-expiratory pressure.

Positive airway pressure maintained at end-expiration during mechanical ventilation. It recruits collapsed alveoli, improves oxygenation, and reduces ventilator-induced lung injury, but excessive levels impair venous return and can cause barotrauma.

Delivery of positive pressure through a mask without an artificial airway. It reduces intubation and mortality in acute hypercapnic exacerbations of COPD and is used for cardiogenic pulmonary edema and selected immunocompromised patients.

Respiratory failure with an arterial carbon dioxide tension above roughly 45 mm Hg, reflecting alveolar hypoventilation. Causes include COPD, neuromuscular weakness, obesity hypoventilation, and sedative toxicity; treatment targets the underlying cause and adequate alveolar ventilation.

A ventilation strategy using low tidal volumes near 6 mL/kg predicted body weight and limited plateau pressures to reduce volutrauma. It improves survival in acute respiratory distress syndrome and is widely applied to other critically ill patients.

Repetitive upper airway collapse during sleep causing apneas or hypopneas with oxygen desaturation and arousals. It produces daytime sleepiness and is associated with hypertension, cardiovascular disease, and motor vehicle crashes.

The number of apneas plus hypopneas per hour of sleep recorded on a sleep study. A value of 5 or more with symptoms, or 15 or more regardless of symptoms, defines obstructive sleep apnea and grades its severity.

Cessation of airflow during sleep without respiratory effort, reflecting instability or loss of central ventilatory drive. It occurs in heart failure as Cheyne-Stokes respiration, after stroke, and with opioid use or high-altitude exposure.

The combination of obesity, daytime hypercapnia, and sleep-disordered breathing after other causes of hypoventilation are excluded. Positive airway pressure therapy improves gas exchange, symptoms, and survival.

Acute infection of the lung parenchyma acquired outside hospital, most often due to Streptococcus pneumoniae. Severity scores guide the site of care, and empiric antibiotics target typical and atypical organisms.

A severity score for pneumonia using confusion, urea above 7 mmol/L, respiratory rate of 30 or more, low blood pressure, and age 65 or older. Higher scores predict mortality and inform admission decisions.

Asymptomatic infection with Mycobacterium tuberculosis without clinical or radiographic disease. It is detected by tuberculin skin testing or interferon-gamma release assays and treated with preventive regimens to reduce progression to active tuberculosis.

Irreversible abnormal dilation of bronchi with chronic cough, purulent sputum, and recurrent infection. High-resolution CT shows dilated airways with thickened walls and loss of tapering; management includes airway clearance and targeted antibiotics.

Annual low-dose CT for high-risk adults, generally ages 50 to 80 with a 20 pack-year history who currently smoke or quit within 15 years. It reduces lung cancer mortality but yields frequent false-positive findings requiring structured follow-up.

Testing of advanced non-small cell lung cancer tissue for driver alterations such as EGFR mutations, ALK and ROS1 rearrangements, and PD-L1 expression. Results determine eligibility for targeted therapy and immunotherapy.

A minimally invasive technique using ultrasound to sample mediastinal and hilar lymph nodes through the airway. It stages lung cancer, helps diagnose sarcoidosis, and obtains tissue for molecular testing.

Pleural fluid is exudative when protein or lactate dehydrogenase exceeds two-thirds of the serum value, or fluid LDH exceeds two-thirds the upper limit of normal serum LDH. These criteria separate exudates from transudates with high sensitivity.

Fluid accumulation in the pleural space due to cancer involving the pleura, most often from lung or breast carcinoma. It causes dyspnea and is managed with thoracentesis, indwelling pleural catheters, or pleurodesis.

Progressive air in the pleural space with positive pressure that collapses the lung and impairs venous return, causing hypotension and hypoxia. It is a clinical diagnosis requiring immediate needle decompression or tube thoracostomy without waiting for imaging.

Diffuse interstitial fibrosis from cumulative asbestos exposure, appearing as basilar reticular opacities with pleural plaques. Latency is typically decades, and the disease is distinct from asbestos-related lung cancer and mesothelioma.

Fibrotic lung disease from inhaling crystalline silica, producing upper-lobe nodules, progressive massive fibrosis, and increased tuberculosis risk. It is irreversible, so prevention through exposure control is essential.

Asthma caused or worsened by workplace exposures, either through sensitization to a specific agent after a latency period or through irritant effects. Diagnosis uses work-related symptom patterns, serial peak flow records, and specific challenge testing.

Reduced total lung capacity with a preserved or increased FEV1/FVC ratio, reflecting small lungs or a stiff chest wall. Causes include interstitial disease, obesity, kyphoscoliosis, and neuromuscular weakness.

The peak negative mouth pressure generated against an occluded airway, reflecting inspiratory muscle strength. A value less negative than about -60 to -70 cm H2O suggests respiratory muscle weakness.

Combined lateral and anteroposterior spinal curvature that restricts chest wall movement, producing a restrictive defect and, in severe cases, chronic hypoventilation and cor pulmonale. Noninvasive ventilation may be required.