Pulmonary/critical care medicine is a broad subspecialty of internal medicine that includes the diagnosis and management of disorders of the lungs, upper airways, thoracic cavity, and chest wall as well as the management of patients in intensive care units. The pulmonary specialist has expertise in neoplastic, inflammatory, and infectious disorders of the lung parenchyma, pleura, and airways; pulmonary vascular disease and its effect on the cardiovascular system; and detection and prevention of occupational and environmental causes of lung disease. Other specialized areas include respiratory failure and sleep-disordered breathing. Critical care physicians generally work in the intensive care units of hospitals and focus on critical illnesses and conditions (e.g., acute and chronic pulmonary disorders, trauma, and heart attacks). Most are internists specializing in pulmonary medicine and manage mechanical ventilators, place pulmonary artery catheters, and perform bronchoscopies; however, some intensivists specialize in anesthesiology, pediatrics, or surgery. The specialty spans the various phases of treatment, from the ambulance to the emergency room, surgical suite, and intensive and cardiac care units. Critical care physicians must be familiar with the surgical and medical problems that put patients in the intensive care unit. They must also know the cardiovascular, fluid, and respiratory management that is required to maintain critically ill patients. The care of critically ill patients raises many complicated ethical and social issues, and the intensivist must be competent in such areas such as end-of-life decisions, advance directives, estimating prognosis, and counseling of patients and their families. Pulmonologists treat a diverse clinical population and can work in private practices or in various hospital settings, including the respiratory therapy department, the pulmonary function laboratory, or the intensive care unit. An in-depth knowledge of internal medicine is useful to these physicians because pulmonary medicine touches upon other subspecialties.