Types of Anesthesia
By Joseph F. Talarico, D.O.
Your anesthesiologist takes several factors into account when recommending the type of anesthesia. Some of those factors include the type of surgery or non-operative procedure being performed and your medical history.
These types of anesthesia are not always clearly defined, and patients may progress from one level of sedation/anesthesia to a lighter or deeper level during the procedure. For this reason, the American Society of Anesthesiologists (ASA) considers anesthesia a continuum, from light sedation to general anesthesia.
For that reason, it is imperative that the physician supervising the administration of sedation/anesthesia be qualified to manage the patient that unintentionally progresses to a deeper level (i.e. from deep sedation to general anesthesia). Understanding that the level of sedation/anesthesia is a continuum, the ASA has published the following definitions:
Levels of Sedation:
Minimal Sedation A level of sedation that relieves anxiety but preserves consciousness. The patient is typically relaxed but readily responds to verbal commands. Blood pressure, heart rate and respiratory function are generally unaffected.
Moderate Sedation A level of sedation that depresses consciousness and relieves anxiety and pain. Under moderate sedation, purposeful response to verbal command or light tactile stimulation is maintained. Blood pressure, heart rate, and respiratory function are generally unaffected or minimally affected.
Deep Sedation A level of sedation in which the patient is not easily aroused, but responds purposefully to repeated or painful stimulation. Blood pressure and heart rate are generally maintained, but intervention may be required to maintain respiratory function.
The patient is completely unconscious, and not responsive to painful stimuli. Blood pressure, heart rate and respiratory function are often compromised.
Local or Regional Anesthesia
Some surgical procedures may be performed under local or regional anesthesia. Local anesthesia involves injecting an anesthetic directly surrounding the operative site, whereas regional anesthesia involves injecting an anesthetic in proximity to the sensory nerves supplying the operative site.
Regional anesthesia includes spinal and epidural anesthesia, as well as various peripheral nerve blocks, which can be used to anesthetize virtually any area of the body.
While these techniques are generally extremely effective in controlling pain, they are often supplemented with sedation or a general anesthetic to enhance patient comfort during surgery. Additional benefits of local or regional anesthesia include enhancement of postoperative pain control.
Who Can Administer Anesthesia
Registered nurses under the direction of the physician performing the procedure can safely administer minimal and moderate sedation. Deep sedation requires the supervision of a physician who maintains expertise in airway management and is able to manage a patient who unintentionally progresses to the level of general anesthesia.
General anesthesia may be administered by an anesthesiologist, a nurse anesthetist under the direct supervision of a physician, preferably an anesthesiologist, or in some states by an anesthesiologist’s assistant under the direct supervision of and anesthesiologist.
The choice of anesthetic or sedation is made by a physician taking into account various factors, including but not limited to the procedure being performed and the general medical condition of the patient.
While minimal and moderate sedation compromise heart and lung function to a lesser degree than deep sedation and general anesthesia, there are circumstances where deeper levels of sedation/anesthesia may in effect enhance safety.