It is a little spoken truth that general anesthesia, the rendering of unconsciousness and the accompanying and important pain elimination it provides, carries with it the unavoidable and incompletely addressable risk of death and permanent or temporary disability. This fact is as true in human medicine as it is in veterinary medicine and these risks will never be completely eliminated.
Why? Because in the artificial manipulation of consciousness comes manipulation of the essential processes of maintaining life, and those processes operate within a varying band of effectiveness that is exceeded at our peril.
Safe general anesthesia, is to some extent an oxymoron, as biological systems are imperfect and the minds that manipulate those systems for intended beneficial purposes are not without flaw. We can only attempt to be careful, thoughtful and honest, but can never guarantee perfection. That's God's domain.
The seeming randomness of anesthetic deaths in veterinary medicine has created fear in the minds of the public, a fear that is not entirely undeserved. Who does not have a story, either personal or second hand, of someone who has lost a pet to anesthesia? Despite huge advances in medicine and science over the last 50 years these losses still occur and the public has little ability to demand safer anesthesia, a mysterious procedure they often fear but do not understand. The pet owning public also does not understand what makes an anesthesia safe and veterinarians vary in the level of service and safety they are able to deliver. Remember too, there is no absolute safety that can be guaranteed.
Young healthy animals are more likely to emerge unscathed from even poorly administered anesthesia whereas animals that have disorders, hidden or otherwise, may not perfectly tolerate even perfectly administered anesthesia. I'll add here, that old age is not a disease. It is not true that age adds risk of anesthesia in and of itself. It is true, however, that older animals have a higher risk of having chronic ailments which themselves may complicate anesthesia. A more complete evaluation before anesthesia is thus warranted in older animals.
Conversely, young animals may compensate for, and thus hide, signs of illness that an older animal may not be able to. Thus there is ample reason to properly evaluate every animal before anesthesia. Finally, full evaluations add costs and since owners must choose whether to allow those precautions and those costs, they are not always done. Some veterinarians work with owners, allowing declination of procedures and some do not allow such declinations.
I do not know if it is true that those regularly doing less precautionary tests and procedures make fewer "I regret to inform you...." telephone calls, however, I am willing to bet that when and if they must make such a terrible call, they can more easily be fully honest in saying that every precaution was taken. No need for excuses or half truths.
The truth is, we do not know in most cases why anesthetic deaths occur. Autopsies ("necropsies" in pets) are rarely done and when they are, are often inconclusive. Unless a defined disease process existed before the pets death, it was likely the consequences of anesthesia itself that led to the unfortunate death of a pet.
What are these consequences? General anesthesia slows down the physiologic processes of life and in so doing renders unconsciousness and insensitivity to pain. These latter characteristics allow surgery and otherwise painful procedures to be done, without pain, often curing or diagnosing disease (tumor removal, exploratory) or leading to a better quality of life for a pet (ovariohysterectomy, castration, dentistry).
In slowing these processes down, certain adverse events cannot be allowed to occur. These include a drop in blood pressure, especially to the brain, with the loss of vascular resistance (muscles in blood vessels relax and blood pressure may fall) that anesthesia brings. Also a drop in body temperature may occur as the bodies chemical reactions slow, producing less heat and if the body cavities are opened, evaporation of normal cavity fluids cools the organs. Too, the reduced flow of blood may lead to reduced heart blood flow as well and this may irritate the heart muscle cells. This can lead to abnormal heart rhythms ("arrythmia") which can also lead to blood pressure dropping and a worsening cycle leading to heart stoppage or brain injury from low blood pressure.
So what to do? In private practice we do not have the student and resident manpower resources that universities and large institutions have, however, very fortunately we do have access to the same sophisticated anesthetic monitoring equipment they have, and we can, should and do make use of that technology to help us create safe anesthetic procedures.
It has been said, "There is no unsafe anesthesia, just unsafe anesthetists." There is a lot of truth to that and yet safety comes at a price. Pet owners should uniformly want that level of safety. If they all did, veterinarians would uniformly have to deliver it. There is no uniformity however, and there can't be because of the great diversity in what the public wants from us and what they are willing to pay for services. Veterinarians can only choose who to serve and try to ensure that the people they want to serve, get the services they want and at a price they are willing to pay.
Real general anesthetic safety comes at a higher price. It involves at least the following:
1. medical history free of signs of disease
2. physical examination within X days of the planned procedure
3. laboratory testing sufficient to determine the absence of overt disease and normally functioning kidneys and liver, and normal blood cell counts within X days of the planned procedure
4. normal electrocardiogram within X days of the planned procedure
5. re-examine day of procedure
6. intravenous catheter with warmed fluid bag hooked up and dripping
7. endotracheal intubation with gas anesthesia
8. working devices to maintain body temperature
9. working inspected anesthesia machine
10. redundant oxygen supply
11. electronic monitor hooked up and reading blood pressure, electrocardiogram, body temperature, oxygen saturation
12. a dedicated (no phone answering, no leaving doctors side) technician recording values and noting unwanted trends in those values
13. a previously formulated and discussed plan on how to address unexpected changes in blood pressure, temperature, electrocardiogram
14. close by presence of labeled, unexpired drugs needed for dealing with unexpected anesthetic issues
15. more warmed fluids available
16. recovery cage nearby and easily observable
17. followup examination as needed to quickly address any post-anesthetic issues
In my opinion, at a minimum, this is what is required to make general anesthesia as safe as it can be.
One can't really evaluate anesthetic judgement on the part of a doctor you otherwise trust. There is no obvious basis on which to do so. You can, however, ask specifically about the above list of interventions as their use implies good anesthetic judgement.
Not every anesthetic event can be completely safe, as is the nature of working with living creatures, especially those that may be ill, however, they can be made as safe as possible by doing all that can be done to minimize risk. These interventions are what I currently do. I am certain that the vast majority of my colleagues also do these things, to make their anesthesias as safe as they can be. I do wish all did so.
You have the right to ask whether your pet will be managed with these interventions. Expect to pay more for a doctor who does these things. In accepting that expense, you are guaranteeing to the extent that any guarantee is possible, that your pet will be as safe as can be. Good medical judgement cannot be directly discerned. In the case of general anesthesia, however, the physical manifestations of the good judgement required to administer it safely can be.
The three posts below are representative of peri-anesthetic deaths that are not fully explained, but that may well have been related to hidden abnormalities, perhaps undetectable in advance. Questions remain, however, about shortcomings in pre-anesthetic evaluation and in anesthetic delivery technique, and those unanswered questions harm the trust that you, the pet owning members of the public have in veterinarians. That concerns me too.
It is my hope that by your learning in detail what makes a safe anesthesia, and by your asking questions about how your pets anesthesia will be managed, and by your demanding the highest level of safety possible and finally by your willingness to pay for that degree of safety, many fewer animals will be lost to anesthesia in the future. I hope you have found this article informative. Thank you
Recent examples of peri-anesthetic deaths: