Sleeping safely. One of the greatest achievements of science!

Some people mentally associate anesthesia with a fatal event. In medicine we refer to the concept of risk in anesthesia.
Some studies in veterinary medicine point out to near 0,1% fatalities and 2% of some sort of complication associated with aesthesia. These statistics will not comfort someone that lost their beloved pet. Nonetheless the vast majority of these cases refer to surgical procedures regarding animals already having fatal conditions. That equals to say that in those cases the risk was very high from the beginning. Considering these facts and in the view of our personal experience we can say that with the present technology veterinary anesthesia is a very safe procedure.

The risk  is dependent on factors as duration of anesthesia, disease status, age and weight of the patient, among others. The main goal of the preanesthetic evaluation is detection of factors which contribute to increased anesthetic risk. The clinical history is crucial to the detection of problems such as allergic reactions to drugs and current medication by the patient, to avoid undesirable drug interactions. It will also detect situations that must be controlled, corrected or improved before the procedure. For example, if we have a history of diabetes we will control the blood glucose before, during and after the anesthetic procedure.

Some of the patients characteristics can directly afect the anesthetic risk. For example, brachiocefalic breeds like the pug, bulldog and persian cat and obese animals can have more dificulty breathing during and after anesthesia. Very young animals (0-3 months old) are very immature concerning internal body control (homeostasis) and thus are very sensitive to hypothermia and dealing with the effects and elimination of anesthetic drugs. Elderly patients require also bigger anesthetic precautions since the cardiac capacity (reserve) is reduced in some of them and there are also concerns regarding drug metabolism.

For a correct risk control we routinely evaluate some clinical parameters, the most common being: complete blood count, liver and kidney function, blood proteins, blood glucose levels, coagulation parameters and cardiac function evaluation.
The anesthetist's role is to use all this collected information and decide the better anesthetic protocol for each situation. The risk analysis and the risk-reducing strategies will always be communicated to the owner.

During the surgical intervention the anesthetist continually controls the animals vital parameters such as blood pressure, ventilation parameters, cardiac function parameters, correct O2 uptake and CO2 elimination, respiratory volume, among many others. Assisted ventilation will be performed if needed and/or if the anesthetic or surgical protocol requires that assistance.
To follow these parameters several machines will display values continually to the anesthetist.

Some anesthesia techniques are associated with greater safety margins because they are lighter on vital organs such as the heart. Because they control pain next to the region being operated the other central nervous system depressing anesthetics can have their dose reduced. One well known example is the epidural anesthesia. In our center we use this technique in every procedure "between the belly button and the tail".
In the majority of the surgical procedures it is very important that the stomach of the patient is empty to prevent him from vomiting during the anesthetic period. The animal should not eat in the 12 hour period before the operation. Paediatric patients have smaller glucose levels stored in the body so this period of fasting should be reduced to 3-4 hours, with exceptions.
Some medications need to be discontinued before the anesthesia, others do not.
As the main ideas to retain from this article we' d like to highlight that anesthesia in veterinary medicine is a very safe procedure and that the preoperative evaluation should strive to identify important individual and clinical parameters before the procedure.




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