Wednesday, July 19, 2017

Anaesthesia, anaesthetic awareness, risks and opportunities

Hero couldn't stay away from my copy of Anaesthesia: The Gift of Oblivion. 

Do animals experience anaesthetic awareness? I don’t know the answer, but the question is more complicated than you think. When a colleague asked me this question a few weeks ago, I went looking for literature and found very little. What I did discover was an incredible book, Anaesthesia: The Gift of Oblivion by journalistKate Cole-Adams.

She became intrigued by the question many years ago, when she met a woman at a dinner party who recounted being conscious during a caesarean when she had been given a general anaesthetic. The experience was traumatic, and had an ongoing impact on the patient. Hearing this story prompted Cole-Adams to undertake a decade-long exploration:
Each day specialist doctors known as anaesthetists (or, in America, anaesthesiologists) put hundreds of thousands of people like you and me into chemical comas to enable other doctors to enter and alter our insides. Then they bring us back again. It is mind-blowing. But quite how this daily extinction happens and un-happens remains uncertain. Researchers know that a general anaesthetic acts on the central nervous system – reacting with the slick membranes of the nerve cells in the brain to hijack responses such as sight, touch and awareness. They have nominated areas and processes they know are important: the microscopic channels through which neurons blast their chemical relays; the electrical circuits that pulse and groove between different regions of the brain. But they still can’t agree on just what it is that happens in those areas, or which of those things that happen matter the most, or why they sometimes happen differently with different anaesthetics, or even on the manner – a sunset? An eclipse? – in which the human brain segues from consciousness to not.
In interviews with anaesthetists, psychologists, hypnotists, scientists and people who have had experiences of anaesthetic awareness, Cole-Adams asks some of the philosophical questions about anaesthesia, like whether pain occurs when we are unconscious (and what the impact of that might be), and whether if it does occur, but is forgotten, it matters? What is the nature of this awareness, is it all one big hallucination, or something else?

Anaesthetic awareness isn’t something that simply happens when you underdose a patient who sits up halfway through surgery and eyeballs you. The subject may be completely “locked in”, unable to move, and oblivious to the medical team. It is said to be extremely rare, but surely is something we should be concerned about – after all, anaesthesia is meant to stop the patient from feeling, experiencing.

As Cole-Adams explains, anaesthetic awareness may not be bad per se, but it may have long term effects on the behaviour of the patient. This, she says, “carries risks and opportunities”. Suppose, for example, you could have a positive impact on clinical outcomes if you said positive things to the human patient while they are anaesthetised? Cole-Adams doesn’t explore what might happen to animals, but I found myself asking whether some of the strategies explored by scientists might improve outcomes in animal patients. For example, if our patients can hear, would it be beneficial to talk in reassuring tones? Human patients feel better if their name is spoken to them as they emerge from anaesthesia – what about dogs and cats? (How do we know or not know?).
Cole-Adams explores the concept of consciousness and what this means for humans. Do we have a continuous self? Are our loved ones simply a working hypothesis that we test through observation? Why might things we don’t know we know – things stored unconsciously – impact our behaviour. 

(One of my favourite passages is where she declares that “Consciousness is a small boat on an immense sea. We may learn to row, we may even rig up a sail, but we can’t know what’s beneath, let alone control it.” It reminds me of a painting by Helen Norton, called He Was In Control)

Post-operative cognitive dysfunction is a documented phenomenon in human patients – does it occur with animals? How could we detect it and, importantly, how could we prevent it?   

While my questions about animals weren’t answered in this book (Cole-Adams focuses on human patients), it is a fascinating combination of science and humanities, covering some amazing experiments and explaining why – although they could be done in the 1960s – today’s ethics committees would not approve, exploring the history of anaesthesia, and linking this with the subjective experience of patients. As a veterinarian, we don’t have access to the latter even by self-report, and there are some major differences between anaesthesia of humans and animals. We don’t, for example, use BIS (bispectral index) monitors to measure brain activity, and as far as I know there are no long-term studies looking at animal behaviour pre- and post- anaesthesia, or indeed looking at the impact of anaesthetic complications on post-operative behaviour in any systematic way.

I recommend this book to anyone interested in medical journalism and pathography, philosophy of science, anaesthesia or psychology. It is beautifully written, well-researched, and represents the fruit of a truly multidisciplinary “slow-burn” project.

Anaesthesia is available through Text Publishing.