One of the first major discoveries relevant to the field of pulmonology was the discovery of pulmonary circulation. Originally, it was thought that blood reaching the right side of the heart passed through small 'pores' in the septum into the left side to be oxygenated, as theorized by Galen; however, the discovery of pulmonary circulation disproves this theory, which had previously been accepted since the 2nd century. Thirteenth century anatomist and physiologist Ibn Al-Nafis accurately theorized that there was no 'direct' passage between the two sides (ventricles) of the heart. He believed that the blood must have passed through the pulmonary artery, through the lungs, and back into the heart to be pumped around the body. This is believed by many to be the first scientific description of pulmonary circulation.[3]
Although pulmonary medicine only began to evolve as a medical specialty in the 1950s, William Welch and William Osler founded the 'parent' organization of the American Thoracic Society[4], the National Association for the Study and Prevention of Tuberculosis.[5] The care, treatment, and study of tuberculosis of the lung is recognised as a discipline in its own right, phthisiology.[6] When the specialty did begin to evolve, several discoveries were being made linking the respiratory system and the measurement of arterial blood gases, attracting more and more physicians and researchers to the developing field.[7]
Surgery of the respiratory tract is generally performed by specialists in cardiothoracic surgery[8] (or thoracic surgery)[9], though minor procedures may be performed by pulmonologists. Pulmonology is closely related to critical care medicine[10] when dealing with patients who require mechanical ventilation. As a result, many pulmonologists are certified to practice critical care medicine in addition to pulmonary medicine. There are fellowship programs that allow physicians to become board certified in pulmonary and critical care medicine simultaneously. Interventional pulmonology is a relatively new field within pulmonary medicine[11] that deals with the use of procedures such as bronchoscopy[12] and pleuroscopy to treat several pulmonary diseases.[13] Interventional pulmonology is increasingly recognized as a specific medical specialty.[14]
The pulmonologist begins the diagnostic process with a general review focusing on:
hereditary diseases affecting the lungs (cystic fibrosis[15], alpha 1-antitrypsin deficiency)
exposure to toxicants (tobacco smoke,[16] asbestos, exhaust fumes, coal mining fumes, e-cigarette aerosol,[17])
exposure to infectious agents (certain types of birds, malt processing)
an autoimmune diathesis that might predispose to certain conditions (pulmonary fibrosis, pulmonary hypertension)
Physical diagnostics[18] are as important as in other fields of medicine.
Inspection of the hands for signs of cyanosis or clubbing, chest wall, and respiratory rate.
Palpation of the cervical lymph nodes, trachea and chest wall movement.
Percussion of the lung fields for dullness or hyper-resonance.
Auscultation (with a stethoscope) of the lung fields for diminished or unusual breath sounds.
Rales or rhonchi heard over lung fields with a stethoscope.
As many heart diseases can give pulmonary signs,[19] a thorough cardiac investigation is usually included.
Pulmonary clinical procedures include the following pulmonary tests and procedures[20][21]:
Laboratory investigation of blood (blood tests). Sometimes arterial blood gas measurements are also required.
Spirometry the determination of maximum airflow at a given lung volume as measured by breathing into a dedicated machine; this is the key test to diagnose airflow obstruction.
Pulmonary Function Tests including spirometry, as above, plus response to bronchodilators, lung volumes, and diffusion capacity, the latter being a measure of lung oxygen absorptive area
Bronchoscopy[22] with bronchoalveolar lavage (BAL), endobronchial and transbronchial biopsy and epithelial brushing
Scintigraphy and other methods of nuclear medicine
Positron emission tomography[25] (especially in lung cancer)
Polysomnography (sleep studies[26]) commonly used for the diagnosis of sleep apnea
Surgical procedures
Major surgical procedures on the heart and lungs are performed by a thoracic surgeon.[27] Pulmonologists often perform specialized procedures to get samples from the inside of the chest or inside of the lung. They use radiographic techniques to view vasculature of the lungs and heart to assist with diagnosis.