Critical care is provided for patients who are suffering from life-threatening conditions. The doctors who work with these people are often called intensivists. They focus on a range of different issues, so they can serve people who need immediate and life-saving care. Since people who need critical care are suffering from such a wide variety of issues, intensivists must have a thorough understanding of diverse types of medical issues and the devices and medications needed to treat them.

An oncologist is a medical professional who has the education and training necessary to diagnose and treat various type of cancers. Oncologists practice in hospitals and medical centers, university hospitals, and research organizations. In addition to diagnosing and treating tumors and cancer, they conduct research to learn more about cancer and how it acts in the body to help develop new treatment options.

An internist or Internal Medicine doctor is someone who specializes in diagnosing and treating illnesses, diseases, and health problems. Most internists are also primary care doctors and treat patients on a regular basis. They can diagnose and treat common illnesses or more serious problems. Most people see an internist regularly. Those with chronic illnesses may do so on a monthly or even weekly basis. Internists are the most common types of doctors.

A Pulmonologist is a healthcare professional who specializes in pulmonary care or lung care. Pulmonologists diagnose, treat, and research pulmonary diseases and problems. They may have special knowledge of other types of internal medicine and specialties, as well, and they work closely with other doctors to help make patients comfortable and improve their health.