Rachel Benmayor was giving birth to her second child via emergency caesarean section when it happened. She was put to sleep. But after blacking out briefly, she regained consciousness and awoke to excruciating pain. Ms Benmayor spent most of the operation awake: aware of voices, movement and pain, but unable to move due to the muscle blockade used in anaesthetics. It's the stuff of nightmares — and anaesthetists refer to it as "accidental awareness". Your anaesthesia experiences Ms Benmayor's story inspired author Kate Cole-Adams to write Anaesthesia: The Gift of Oblivion and the Mystery of Consciousness, which explores the experience of pain and what happens when patients wake up under the knife. Thankfully, that kind of experience is relatively rare. "One to two people in every thousand remember waking under an anaesthetic, and only a very small portion of them would be in terrible pain," Cole-Adams says. For those unlucky few, the experience, often likened to being trapped under a sheet of heavy glass, is terrifying and the emotional impact is enduring. When Cole-Adams appeared on RN's Life Matters, the show was inundated with people who wanted to share their experiences of anaesthesia gone wrong. "I woke up under anaesthetic and couldn't move or talk. I could hear them talk and feel the pain. I thought I was in the park being stabbed and murdered. The paralysis lasted as I came round and I started to choke and suffocate as I couldn't clear my throat. Fortunately, the staff realised and gave me oxygen until the paralysis went away." — Frances The experience of consciousness and paralysis while under anaesthesia is often associated with post-operative trauma and profound psychological disturbance. "After my elderly mum awoke from a broken leg operation, she was suffering hallucinations for many weeks; her terror was pitiful to watch. She suffered some long-term damage after that, with [the] occasional re-emergence of hallucinations." — Anna While waking up under anaesthesia is rare, many more patients are left with fragments of memories and a sense that something has occurred. "I recently had a general anaesthetic. I swear to this day I saw someone in surgery drop something red coloured and it smashed on the floor. I asked about it and they said I was dreaming." — Joy These examples suggest that anaesthesia-induced unconsciousness is characterised not by the absence of cognitive activity but rather its disruption. According to a thesis posited by George Mashour, professor of anaesthesiology and neurosurgery at the University of Michigan, anaesthetics interrupt what's known as "cognitive binding". Information continues to reach the brain, but the capacity to synthesise and integrate that information is compromised. Dr Mashour likens the process to an orchestra falling apart. "I broke my arm when I was about 11 and I woke during the setting of the arm. I thought I was in a dream and tried to move my head: my vision was blurry and I saw the large face of someone loom over me and say (in what seemed to be a slow droning voice) 'turn it up'. I looked at the ceiling, which was those white tiles ... to this day those white perforated ceiling tiles always remind me of it." — Elaine Anaesthesia getting safer Despite the disturbing experience of some patients, modern anaesthesia is extremely safe. "The death rate from general anaesthesia had dropped in the past 30 years from about one in 20,000 to one, maybe two, in 200,000," Cole-Adams says. "It's easy to forget that until the middle of the 19th century there was no general anaesthesia. In 1846 the first actual demonstration of anaesthesia happened and it was with a drug called nitrous oxide, which is still the workhorse of a lot of today's anaesthetics. "Laughing gas, which was developed along with ether at about that time, was world-changing: it changed medicine." Since then, the art of anaesthesia has been progressively refined. Today's anaesthetic cocktails are carefully titrated combinations of three elements: hypnotics, to induce unconsciousness; analgesics to mitigate pain; and a muscle blockade to prevent movement. The introduction of the last element in the 20th century revolutionised the process, allowing anaesthetists to lower doses and reduce the depth of unconsciousness. However, according to Cole-Adams, that means that for today's anaesthetists there is no way to be sure that a given patient is asleep, particularly once they are paralysed and cannot move. For all the advances in medicine and technology, the exact science of anaesthesia remains elusive. "Fundamentally, we still don't know how those drugs bring about unconsciousness," Cole-Adams says. Memories revealed by hypnosis More mysterious still is the nature of unconsciousness induced under anaesthesia. It's a problem that has long captivated the imaginations of doctors, researchers and writers. Just over half a century ago, Bernard Levinson, a psychiatrist in Johannesburg, conducted a dramatic and unrepeatable experiment. Ten dental patients were given an ether-based anaesthetic. During the operation, Dr Levinson staged a mock-crisis in which the surgeon was asked to exclaim, "I don't like the patient's colour. Much too blue. I'm going to give a little more oxygen." None of the patients had any memory of the event when they woke up. However, under hypnosis a month later, four could quote the surgeon's words verbatim and another four could remember fragments of the event. Though methodologically flawed and ethically problematic, the experiment illuminated a problem at the heart of anaesthesia, Cole-Adams says. Source
