Anesthesia awareness

Anesthesia awareness, or ‘intra-operative awareness’ occurs during general anesthesia, when the patients receives muscle relaxants but not enough general anesthetic or analgesic to prevent consciousness or, more importantly recall of events.

The experience is often extremely traumatizing for the patient who is unable communicate their distress due to the muscle relaxants.

Most current cases are attributed to human error. The others are thought to be due to either a predisposed tolerance or a tolerance induced by the interaction of other drugs. The causal human errors include inadequate drug dose, inadequate monitoring and failure to refill the anesthetic machine’s vaporisers with volatile anesthetic.

The prevalence of anesthesia awareness ranges from 0.1% to 0.2 %, or up to 4000 cases per year. The effects usually extend further than the event itself. Many victims experience post-traumatic stress disorder (PTSD), leading to long lasting after-effects such as nightmares, flashbacks, insomnia. It is also highly comorbid with alcoholism.

As with all forms of medical error, incidents of awareness are under-reported. Inadequate education about the full impact of awareness leads to an inadequate response by anesthesiologists and delayed treatment for victims. In many cases, doctors have ignored the post-operative complaints and have not referred patients for appropriate counselling.

As an additional preventative measure, some hospitals use a new device called a bispectral index monitor (BIS). BIS monitors features of the electrical pattern of brain activity, the electroencephalogram (EEG). It is unclear whether the use of BIS by anesthesiologists actually reduces the incidence of awareness. Victims contend that if such a device only prevents a few incidences, it is worthwhile.

Promininent victims

• Carol Weihrer, an activist