Definition of Anesthesia awareness
Anesthesia awareness: The situation that occurs when a patient under general anesthesia becomes aware of some or all events during surgery or a procedure, and has direct recall of those events. Because of the routine use of neuromuscular blocking agents (also called paralytics) during general anesthesia, the patient is often unable to communicate with the surgical team if this occurs.
The frequency of anesthesia awareness has been found to range between 1 and 2 per 1,000 patients undergoing general anesthesia. (The administration of general anesthesia to 21 million patients annually in the US translates to the occurrence of 20,000 to 40,000 cases of anesthesia awareness each year.) Patients experiencing awareness report auditory recollections (48%), sensations of not being able to breathe (48%), and pain (28%). Over half of these patients experience mental distress following surgery, including an indeterminate number with PTSD (posttraumatic stress disorder).
The frequency of anesthesia awareness has been found in multiple studies to range between 1 and 2 per 1,000 patients undergoing general anesthesia. (The administration of general anesthesia to 21 million patients annually in the US translates to the occurrence of 20,000 to 40,000 cases of anesthesia awareness each year.)
Patients experiencing awareness report auditory recollections (48%), sensations of not being able to breathe (48%), and pain (28%). Over half of these patients are reported to experience mental distress following surgery, including an indeterminate number with . Some patients describe these occurrences as their "worst hospital experience," and some determine to never again undergo surgery. Some patients describe these occurrences as their "worst hospital experience," and some determine to never again undergo surgery.
The incidence of awareness is reported to be greater in patients in which the dose of general anesthetic must be smaller and carefully titrated to decrease significant side effects, for example, a patient who is hemodynamically unstable. Procedures typically identified as falling into this category are some cardiac, obstetrical (for example, C-section) and major trauma cases. Factors contributing to the risk of anesthesia awareness include the increasing use of intravenous (IV) delivery of anesthesia, as opposed to inhalation anesthesia, and the premature lightening of anesthesia at the end of procedures to facilitate turnover of the operating room.
Monitoring patients under general anesthesia to prevent anesthesia awareness can be challenging. Despite a variety of available monitoring methods, awareness is difficult to recognize while it is occurring. Typical indicators of physiologic and motor response, such as high blood pressure, fast heart rate or movement, or hemodynamic changes, are often masked by the use of paralytic agents to achieve necessary muscle relaxation during the procedure, as well as the concurrent administration of other drugs necessary to the patient's management, such as beta-blockers or calcium channel blockers.
To overcome the limitations of current methods to detect anesthesia awareness, new methods are being developed that are less affected by the drugs typically used during general anesthesia. These devices measure brain activity. These electroencephalography (EEG) devices are also called level-of-consciousness, sedation-level and anesthesia-depth monitors. These devices may have a role in preventing and detecting anesthesia awareness in patients with the highest risk.
The anesthesia professional must often balance the psychological risks of anesthesia awareness against the p-physical risks of excessive anesthesia for many critical medical conditions. Anesthesia awareness is also called unintended intraoperative awareness.
Last Editorial Review: 10/28/2004
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