Anesthesiology Principles: Decoding The Mystery

By Alfreda Miller-Coleman, MD

Have you ever been intrigued by anesthesiology and its basic principles? Were you aware there are several types of anesthesia available to patients? Because anesthesia may be viewed as an enigma, my goal is to provide a brief explanation regarding anesthesiology and the services available for patients.

Anesthesiology (the study of anesthesia) is a specialty of medicine concerned with the perioperative care of patients. Perioperative describes anesthesia care that is provided to patients before, during, and after their surgical procedures. Physicians, who are known as anesthesiologists, have twelve or more years of postgraduate training and are responsible for ensuring that patients receive anesthesia care safely. Nurses or assistants may help in the provision of anesthetic care, although this is not a requirement. Patients are evaluated before surgery, managed throughout the surgical procedure, and monitored while recovering from anesthesia and surgery.

The type of anesthesia necessary for surgery is determined by the nature of the surgical procedure. Developing a plan for the patient’s care throughout the perioperative process is the responsibility of the anesthesiologist. The anesthesiologist reviews the patient’s medical history and has a detailed conversation regarding the surgical procedure and the appropriate anesthetic. Educating the patient regarding their anesthesia and the options available for their care is of paramount importance.

The delivery of anesthesia is safer now due to the advances in monitoring and the improvements in the medications utilized. The American Society of Anesthesiologists, a national organization that maintains the standards of practice, mandates that vital signs and levels of oxygen, carbon dioxide, and anesthetic gases are monitored during every anesthetic performed. Other parameters such as circulatory functions and blood gases are monitored as well, depending upon the type of surgery and the patient’s medical history. There are many medications involved during the anesthetic process. These medications, some of which have been utilized for years, have been tested and approved by the Food and Drug Administration. As time has progressed, medications with better safety profiles and limited side effects have been developed for safe use during the perioperative process.

There are four different types of anesthesia: general, regional, sedation, and local. General anesthesia involves using intravenous (IV) medications and anesthetic gases to render a patient unconscious. The patient is unaware of their surroundings and the sensation of pain. Anesthetic gases are given to the patient through a breathing tube or a mask. The breathing tube or mask is connected to an anesthesia ventilator by a long tube commonly known as an anesthesia circuit. The anesthetic gases and oxygen flow from the anesthesia machine to the patient. Depending on the type of surgery, the anesthesia team will connect the patient to the ventilator or allow the patient to spontaneously breathe. The anesthetic state is maintained until the completion of the surgical procedure. Throughout the course of the procedure, multiple medications are administered to the patient. Some of these medications maintain a state of relaxation, control vital signs, assist with pain control, and prevent nausea from the anesthetic. At the end of the surgical procedure, the anesthetic gas is discontinued and the patient is allowed to awake from the anesthetic state. The patient is taken to the recovery unit for post-anesthesia care. 

Regional anesthesia occurs when a local anesthetic is used to anesthetize or alleviate the sensation of pain from the portion of the body requiring surgery. Examples of regional anesthesia include epidural, spinal, and peripheral nerve blocks. Epidurals involve the placement of medication within the epidural space in the spinal area. This space is accessed with a special needle large enough to inject medications through the needle or through a special catheter that is placed within the space. Epidurals are commonly used to help relieve pain for women throughout the laboring process. They are also utilized for patients requiring joint replacements, lung procedures, or abdominal surgery. In the case of chronic pain management, some patients receive medications within the epidural space to assist with pain and inflammation from spinal lesions caused by degenerative disease and injuries.

Spinal anesthesia, a technique like epidural anesthesia, can be used for some of the same reasons previously stated. A spinal block is achieved by injecting medication through a small needle into the fluid that surrounds the spinal cord. Spinal blocks are commonly used for cesarean sections, as well as for joint replacements and repair of lower extremity fractures. Peripheral nerve blocks entail anesthetizing a specific area of the body by placing local anesthetic around nerves that give sensation or movement to that part of the body. For example, the nerves that control the shoulder joint can be anesthetized; therefore, the patient has a decreased level of pain after the surgical procedure. Other common areas of the body that can be anesthetized include the elbow, hand, knee, and foot. Peripheral nerve blocks can also alleviate pain within the chest wall and the abdomen. 

Sedation, which is also known as monitored anesthesia care (MAC), involves the administration of intravenous medications to create a state of drowsiness. This category of anesthesia can be used alone or in combination with regional or local anesthesia. Sedation can be classified as mild, moderate, or deep. Mild sedation is achieved when patients are given medications to relax and relieve anxiety. Patients maintain the ability to communicate with anesthesia providers. Mild sedation is commonly used when a large amount of anesthetic is not required due to the type and length of the procedure. One example is cataract surgery. With moderate sedation, also known as “conscious sedation”, patients are drowsy.  However, they are still able to respond to verbal or tactile stimulation. It frequently accompanies procedures in which regional anesthesia is the primary anesthetic. The patient is moderately sedated for comfort and management. Deep sedation occurs when a patient is sedated to the point where they are only responsive to repeated painful stimuli. An example of deep sedation is the administration of propofol for endoscopy and colonoscopy procedures.  

Lastly, local anesthesia results when a small area of the body is injected with local anesthetic medication or covered with an anesthetic cream. The patient is conscious or may receive a form of sedation when this type of anesthesia is used. It is appropriate for suturing lacerations or for dental procedures. Anesthetic cream is used to assist in the placement of intravenous access in children.

During your lifetime you may need a surgical procedure that will require one of the types of anesthesia described in this article. Many patients present with a degree of apprehension regarding anesthesia and its administration. The best way to combat fear is to educate yourself regarding the specialty of anesthesiology and how it is practiced. Therefore, a well-informed patient will no longer view anesthesiology as a mystery.