Steven Lefevor
Hemodynamic influence of acepromazine or dexmedetomidine premedication in isoflurane-anesthetized dogs
Prior to induction of general anesthesia of stable patients, medical professionals first start by administering a premedication. This is an essential part of safe anesthetic management. The purpose of the premedication is to sedate the patient marginally, and to help provide other optimal conditions prior to surgery,including, reduction of anxiety and pain, minimized cardiopulmonary depression, reduction of secretions, minimizing postoperative nausea and vomiting, etc. Once the premedication is given, it allows medical professionals to commence induction of general anesthesia in the patient for the specific surgery they will be having. In this acclaimed article for veterinarians, two common premedication’s used in veterinary medicine are evaluated. The two premedication’s being evaluated are; acepromazine and dexmedetomidine. The scientists performing this study want to know what the effects of these two premedication’s have on the cardiovascular system, and which medication is the most optimal for the patients.
Using the scientific method, scientists began to form a hypothesis. They presumed that acepromazine would lower the patient’s blood pressure prior to being anesthetized.They found that once further inducing agents were given, such as propofol and isoflurane; the patients would become hypotensive from the acepromazine. They also predicted that the acepromazine would lower the patient’s PCV (packed cell volume, an indicator of red blood cell concentration and oxygen carrying capacity). However, when given domitor, the scientists considered that domitor would increase the PCV, which in turn would increase the oxygen carrying capacity of the patient. Therefore, as soon as further inducing agents were given, such as propofol and isoflurane, the blood pressure would then be within normal limits.
In their evaluation of this hypothesis, they took six patients that happened to be canines all of the same weight and size, and ran preoperative blood work on each of them. Once the blood work came back within normal ranges for each patient, they then began giving the six patients the premedication’s mentioned above, and monitored their vitals in small increments. As soon as the premedication’s were given time to reach full efficiency to the various patients, they then induced each patient using propofol, and proceeded to anesthetized them using isoflurane. Throughout induction vitals continued to be monitored regularly. Monitoring vitals included: checking and counting heart rates, pulse oximetry check, tracking blood pressures, and also recording multiple PCV's on the patients. Anesthesia went on for a small amount of time with the close watch of each patient. They soon woke the patients up from anesthesia all while continuing to monitor the various vitals to account for all changes to happen.
Based on the results they collected from their study, the professionals performing the study were able to compile data showing that dexmedetomidine caused the patients to have hypertension initially, but after being maintained under anesthesia, the patient’s blood pressure improved. The effects that the dexmedetomidine had on the cardiovascular system included a lower heart rate. The acepromazine however, caused the patients to have hypotension and it did not get any better while under anesthesia, and it also caused the patients PCV to decline. Therefore, based off of their results, we find that dexmedetomidine is a better premedication agent because it doesn’t cause the PCV to drop, and it doesn’t leave the patient with hypotension, whereas acepromazine does.
This type of research is invaluable in the field of veterinary medicine. These are medications that are used often and on a daily basis, and it is important that we know the different effects that these drugs will have on our patients so that treatment can proceed accordingly to maintain a safe anesthetic environment. These different drugs must be evaluated correctly using the scientific method so that mistakes don’t happen while the patients are anesthetized, and to rule out the negative attributes of different drugs. There are many other medications out there that are also used in the veterinary field. Studies suck as this could continue to expand, and research other options of premedications that are used in hospitals everywhere, and help detect potential adverse effects that may occur.
Source:
JAVMA:Journal of the American Veterinary Medical Association, April, 1, 2015 Volume 246, Number 7, Page 754.