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.

A general surgeon is a medical professional who performs surgery on patients. General surgeons typically perform common surgeries and have attended college and medical school to learn the skills needed to perform them successfully. They also care for their patients before and after operations and can give an accurate prognosis after the surgery is complete and the patient has had time to heal.

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 nephrologist is a medical professional who specializes in diagnosing and treating diseases and disorders that affect the kidneys. Nephrologists are often referred to as kidney specialists. Some nephrologists also do research that helps them learn more about kidney diseases, so they can produce better treatments for their patients.