The state of "anesthesia" means different things to different individuals and is as much a philosophical state as a neuro-scientific one. While the definition of anesthesia itself, as the loss of "awareness," is rather vague, a pragmatic definition of anesthesia as the provision of a combination of amnesia, analgesia (pain control), and muscle relaxation to allow the performance of surgery or interventional procedures is more useful. Anesthesiologists are also responsible for physiologic homeostasis while the patient is in the anesthetized state providing for the safest and most comfortable perioperative experience possible.
Anesthesiologists and the anesthesia care team, including Certified Registered Nurse Anesthetists (CRNAs) and Anesthesia Assistants (AAs), work to provide a wide range of perioperative services including preoperative evaluation, intraoperative management, post-operative management, intensive care unit (ICU) care, and acute and chronic pain management. The consultant anesthesiologist will function to some degree in all these roles in each patient he/she takes care of, taking into consideration numerous factors when deciding on an anesthetic plan with the surgeon and patient.
This topic discusses an overview of anesthesia and anesthetic choices focusing on intraoperative management and the risks and benefits of anesthetic choices.
GOALS OF ANESTHESIA
The primary goal of anesthesia is the maintenance of physiologic homeostasis. This includes monitoring and treatment of cardiovascular, pulmonary, neurologic and renal functions and changes during the perioperative period to minimize adverse outcomes. Optimizing intraoperative physiology may help speed recovery and provide for perioperative organ system protection.
Amnesia — Amnesia refers to the lack of memory of the intraoperative and perioperative experience. It is reliably achieved by inducing a state of unconsciousness as a result of general anesthesia. A three year study including 87,361 patients found six patients reporting recall under general anesthesia (incidence 0.0068 percent, or 1 per 14,560) . This is the largest study to date looking at recall under general anesthesia. The rate of 1 in 14,560 is lower than the 0.1 and 0.9 percent rate generally reported in the literature. Previous studies have generally focused on specific patient populations at higher risk for recall, such as obstetric, trauma or cardiac patients, while this study included a wide range of procedures. Differences may also be due to observer or surveyor bias, and perceived differences in implicit versus explicit awareness.