Responsiveness under anaesthesia

Hi, My 7 year old female cat recently took a visit to a hospital to investigate sudden pain in her spine which was causing difficulties moving. They performed blood tests, heart exam, MRI and a spinal tap under aneasthesia. The MRI showed signs of inflammation on the lumbar spine and the other tests indicated chronic toxoplasmosis for which she is now on antibiotics. During this process I was informed by the vet herself that my cat woke up during the spinal tap because of the pain it caused due to the position they needed to put her in. This resulted in only a small sample being taken. After asking that this be put formally in the report (since it had been omitted) the vet then revised this wording and ended up formally recording that my cat had become “responsive” during the spinal tap. Since the spinal tap was straight after the MRI, I asked if it had been possible she was awake during the MRI too, to which I had a categorical “no”. When questioned why she became responsive at all, the only explanation I was given was that it was because of the pain. After expressing my concern at the fact that anaesthesia is meant to stop them feeling pain, the vet explained that sometimes when the pain is so great they can actually become responsive… I have been focused on getting my cat better and so continued to work with the vet but as time approaches to take her back for a follow up I am more and more uneasy about the competence of the vet. Particularly if they need to put her under anaesthesia again and repeat the spinal tap. I’d like to understand if it is indeed possible / normal for a cat to become responsive under anaesthesia if the pain is that intense. And if not, what is likely to have happened? It will help make my mind up as to whether to return to the same vet. I expect it’s better for continuity of care that the same vet reassess her but if this is negligence then I will have to seek an alternative practice. thank you for the help.

Hello - I'm sorry to hear that things didn't go too smoothly with your cats' procedure and of course, I wasn't there so am in no position to speak for your vet; as ever, I would recommend asking them about it.  As a vet, I prefer clients to raise such doubts because it helps me to explain in the most helpful way. I am pleased to hear that the MRI was diagnostic. Usually a cat needs to lie very still for a diagnostic MRI to take place; I don't think they could have been awake if this was achieved, unless some kind of immobilising agent was used (that keeps the cat still without them being asleep). The purpose of anaesthesia is two-fold; to keep the animal still and "asleep" in order that the procedure is safe (especially if there is a needle inserted near their spinal cord, which could cause damage) and to control the pain. It is important that someone controls the depth of anaesthesia - too deep and the patient's heart rate and blood pressure may drop - this can even happen to a fatal extent (you will have heard of pets unable to come round).  Too 'shallow' and they risk waking up / moving about / jumping off the table.  Of the two evils, this is the safer one.  Usually there is a nurse whose job it is to measure and report back to the vet on the control the of anaesthetic depth. However, response to pain is not only linked to the depth of anaesthesia - it can also be reduced using pain relief.  Additional pain relief could be given for a spinal tap - for example, local anaesthetic to help the needle go through the skin. 'Responsive' leg movement implies "responsive to (in this case, painful) stimuli" as in, the anaesthetic is too 'light' or the pain relief insufficient given what is happening.  The early signs of this can include the heart-rate increasing and the respiratory rate increasing (HR and RR normally both drop under general anaesthesia).  Depending how quickly this happens, this can progress to the eyes moving around as they do in a sleeping human and sometimes, a limb beginning to move - just as a person might do as they shift into the lighter phases of sleep.  It may end in them waking up. Usually, a nurse will be monitoring the patient's Heart Rate and Rep rate, and various other parameters under GA (often using machines) and will notice this happening, and ask to give more drugs in order 'deepen' the anaesthetic.  This may include a pain-killer.   It would be usual, in surgery, for the nurse to say, 'Hold still - she's waking up a bit' or 'hold on, she's too light' and the vet to stop, while drug doses (usually inhalational drugs at this stage, but sometimes delivered through a drip) are adjusted, in order to make the anaesthetic deeper.  You might also hear 'he's a bit deep' and for the nurse to reduce the doses until they were satisfied the anaesthetic was safe. Animals do experience / react to strong pain under light anaesthesia, but are probably less conscious of it.  If there is a needle being inserted into an animal's spine, the anaesthetist really would want to the animal to be 'deep' enough not to respond to that pain, because if they wake up enough to move in the wrong direction, they could damage the spinal cord / result in paralysis. For me it sounds as though this patient was responsive to the pain and the vet said 'Right, I don't think it's safe to give any more drugs or try that again let's wake them up,' which is a safe way to respond to a less-than-ideal situation.  Different cats react differently to different situations and if your vet wasn't confident putting a needle into the spine or make the pain relief deeper, the correct thing to do would be to abandon it. A Good question might be, 'Could something be done differently in order to stop this from happening again if the procedure was to be repeated?' I find it encouraging that your vet didn't continue with a procedure they felt to be unsafe;  they woke the patient up and were honest enough that they reported what happened to you.  However, it does sound as though the two of you need a good talk - and you need to air your concerns and hear their responses. I don't know how experienced your vet is, but it may also be possible to refer the case to someone more experienced for your peace of mind.

Oh dear, I do seem to have written an essay.  In short:

• The level of pain relief, depth / safety of anaesthesia and immobilisation of the patient can be a constant juggling act throughout a procedure, especially a painful one.
• Its sounds as though the vet felt unable to get it right on this occasion; if they are going to try again, I would hope that they have some idea of what to do differently.  Another face to face chat might help, now that you are both calmer. Alternatively, they might also consider referral.
• It is encouraging that the vet identified that conditions were not ideal, woke the patient up and admitted to you that they had been concerned; this is considerably better than pressing on with a procedure and risking damage to your cat.
• I hope that something there is of help.