What are the cardinal symptoms of respiratory-system disease?
Cough and dyspnea.
What types of causes can dyspnea have?
Pulmonary or non-pulmonary causes.
What does chest tightness or inability to take a deep breath suggest?
Obstructive lung disease.
What does air hunger or a sense of suffocation suggest?
Congestive heart failure.
When is a cough classified as acute?
When it lasts less than 3 weeks.
What does wheezing suggest?
Airway disease such as asthma or COPD.
What does stridor suggest?
Upper-airway obstruction.
What does dull percussion indicate on physical examination?
Pleural effusion.
What is the extent of the conducting zone in the airway?
It extends from the nose to the terminal bronchioles.
What is the function of the conducting zone in the respiratory system?
It transports gas without gas exchange.
What is the anatomic dead space volume of the conducting zone?
About 150 mL of air.
Which structures make up the respiratory zone?
Respiratory bronchioles, alveolar ducts, and alveolar sacs.
Where does gas exchange occur in the lungs?
In the respiratory zone.
What percentage of the alveolar surface do Type I pneumocytes cover?
They cover 96–98% of the alveolar surface area.
What is the primary function of Type I pneumocytes?
They perform gas exchange.
What are the characteristics of Type II pneumocytes?
They cover 2–4% of alveolar surface, are small cuboidal cells at alveolar corners, produce surfactant, and can become Type I pneumocytes.
What are the two types of blood supply to the lungs?
Pulmonary circulation and bronchial circulation.
What type of blood does pulmonary circulation carry to the alveoli?
Deoxygenated blood.
Where does pulmonary circulation return blood after gas exchange?
To the left atrium.
What does bronchial circulation supply with oxygenated blood?
Conducting airways and surrounding tissues.
What percentage of cardiac output does bronchial circulation receive?
1–2%.
How much bronchial blood returns to the right atrium?
About one-third.
How much bronchial blood returns to the left atrium?
About two-thirds.
What three processes are required for successful oxygenation and CO2 elimination?
Ventilation, perfusion, and diffusion.
What are the four basic lung volumes?
Inspiratory reserve volume, tidal volume, expiratory reserve volume, and residual volume.
What are the four lung capacities?
Inspiratory capacity, functional residual capacity, vital capacity, and total lung capacity.
How is each lung capacity formed?
By the sum of two or more lung volumes.
What does spirometry measure?
How a person inhales and exhales air volumes as a function of time.
What is forced vital capacity?
The volume delivered during a forceful and complete expiration after full inspiration.
What is forced expiratory volume in one second?
The volume delivered during the first second of a forced vital capacity maneuver.
Which lung volumes or capacities cannot be directly measured by spirometry?
Residual volume, total lung capacity, and functional residual capacity.
What causes an obstructive ventilatory defect?
Hindrance to airflow.
What characterizes an obstructive ventilatory defect?
Decreased airflow and decreased FEV1/FVC ratio.
What causes a restrictive ventilatory defect?
Inability to expand the alveoli.
What characterizes a restrictive ventilatory defect?
Decreased lung volume including total lung capacity and forced vital capacity.
When is FEV1/FVC considered low?
When it is less than 70%.
When is FVC considered low?
When it is less than 80% of predicted.
What does the acronym P-A-I-N-T stand for in restrictive causes?
Pleura, alveoli, interstitium, neuromuscular disease, thoracic abnormalities.
When does work of breathing increase?
With increased ventilation, mechanical load from reduced compliance or increased airflow resistance, or both.
What characterizes perfusion-limited gas exchange in pulmonary capillaries?
Gas equilibrates near the beginning of the capillary, so transfer increases mainly by blood flow.
Why is gas exchange diffusion-limited in some pulmonary conditions?
Gas does not equilibrate by the end of the pulmonary capillary.
Which gases behave diffusion-limited during strenuous exercise or lung disease?
Carbon monoxide and oxygen.
What is ventilation-perfusion heterogeneity?
Mismatch between alveolar ventilation and perfusion including wasted ventilation and shunt.
What lung function changes occur in idiopathic pulmonary fibrosis?
Increased elastic recoil, low lung volumes, normal airway resistance, reduced diffusing capacity, and low oxygenation.
What causes airway narrowing in acute asthma?
Smooth-muscle constriction, inflammation, and bronchial thickening.
How does acute asthma affect lung function tests?
Decreased FEV1/FVC, elevated FRC and RV, normal TLC, and normal diffusing capacity.
What lung function changes occur in severe emphysema?
Decreased elastic recoil, decreased FEV1/FVC, elevated lung volumes, and decreased FVC and FEV1.
Which views are included in routine chest radiography?
Posteroanterior, lateral, and lateral-decubitus views.
What type of imaging is non-ionizing and guides thoracentesis?
Ultrasound.
What does computed tomography assess in respiratory imaging?
Hilar and mediastinal disease.
How does contrast help in computed tomography?
It distinguishes vascular from non-vascular structures.
What is a use of high-resolution chest CT?
Assessing interstitial lung disease.
How does PET scanning identify malignant lung lesions?
By their increased glucose uptake.
Which lung lesions can cause false negatives on PET scans?
Carcinoid tumors, bronchoalveolar carcinoma, and lesions smaller than 1 cm.
How does pulmonary angiography demonstrate pulmonary embolism?
By showing a filling defect or abrupt termination of a pulmonary vessel.
How can sputum be collected in respiratory medicine?
Through spontaneous expectoration or sputum induction.
What are the purposes of thoracentesis?
Thoracentesis has diagnostic and therapeutic purposes.
What imaging guidance may be used during thoracentesis?
Ultrasound guidance may be used during thoracentesis.
What does bronchoscopy directly visualize?
The tracheobronchial tree is directly visualized by bronchoscopy.
What are the purposes of bronchoscopy?
Bronchoscopy has both diagnostic and therapeutic purposes.
What procedures does medical thoracoscopy or pleuroscopy allow?
It inspects the pleural surface, samples or drains pleural fluid, and permits pleural biopsy.
Under what conditions is medical thoracoscopy performed?
It is performed under conscious sedation and local anesthesia.
What advantage does thoracotomy have over VATS for biopsy?
Thoracotomy provides larger biopsy samples and can excise lesions too deep or near vital structures for VATS.
Test your knowledge with 30 questions on Respiratory Physiology and Diagnostics.
1. In respiratory-system disease, which symptoms are considered the cardinal ones?
2. A patient reports air hunger and a sense of suffocation; which description best matches the likely dyspnea pattern?
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