Dr. Anna Dunton-Gallagher
OFF THE LEASH
This week’s article is a follow-up to last week’s introduction to anesthesia. In that article I talked about the steps leading up to anesthesia, while today I will talk about what happens during and immediately after.
While patients are under anesthesia, we measure several things. One is with an EKG or electrocardiogram. This measures heart rate and shows us a graph of each heartbeat. This makes sure that we are alerted immediately if any small part of a heartbeat changes. An EKG gives us information about how each part of the heart is beating, and how the charges are being conducted across it. Changes in different parts of the waves mean different things and are treated differently.
Next, we measure blood pressure. This helps us monitor heart function, depth of anesthesia and hydration. Blood pressure is one of the most simple measures that give us a lot of information. We are able to tell if a pet is too light (getting wakeful) or too deep (body not responding enough) under anesthesia. We are also able to tell if the pet needs more intravenous fluids or less. We help gauge our pain control with this as well.
We measure oxygen saturation of the blood. We expect this number to be almost 100, so if it starts to drop we know immediately that for some reason the lungs are not sending oxygen to the blood properly. We also measure the speed of their capillary (small blood vessel) refill, which tells us how the body is circulating blood and their hydration status.
Temperature is measured. Changes in temperature are normal, because the body doesn’t regulate as well under anesthesia, so we must regulate for the patient. This is done with warming devices, and temperatures let us know how well the body is adapting. A cold soda will hold more gas than warm soda, and a cold patient will hold more anesthetic gas. Because they cannot self-regulate, it is important that we are effectively keeping them warm. This affects the depth of anesthesia and metabolism of the inhaled anesthesia.
We were taught something very important in vet school, and it came up on many tests. This is something I teach my technicians as well. If you see a dramatic change (in any measured value) what is the first thing you do?
The answer is that you look at and listen to the patient. Our technicians are the most valuable asset during anesthesia, as they spend every moment looking at, listening to and feeling your pet.
Once the procedure is over, we still monitor pets very closely as they wake up. At this point, we continue to keep them warm and measure alertness. Once patients are sitting up and watching us, we know that their body is back to regulate them well. We still keep them warm, comfortable and minimally stimulated until they are wiggling, wagging, eating or walking again.
This part of anesthesia is especially important for brachycephalic (smooshy-faced) pets. These pets breathe very well when under anesthesia, but once the endotracheal tube is removed they can struggle to breathe if not completely alert. This is a very important part of anesthesia that requires close attention to detail.
From admission to discharge, we keep a close eye on your pet. Typically the reasons for anesthesia in animals mean a big change in their quality of life. Not wanting a pet to undergo anesthesia usually means leaving them with a chronic condition like painful teeth, a painful leg, or masses that could be taken off before they are bothersome. Make sure that you ask questions of your vet if there is any area that you are worried about. Know that anesthesia is so closely monitored that a veterinarian will not recommend a procedure unless it is in the best interest of your pet.