Total Iv Anesthesia

Animals can be anesthetized using injectable agents, inhalants or a combination of injectable and inhalant agents. Inhalant agents are commonly used to maintain anesthesia in veterinary practice for longer surgical procedures; however, injectable agents (IV or IM) have been used in shorter surgical procedures. There are advantages and disadvantages associated with the use of injectable agents for the induction and maintenance of anesthesia. Induction of anesthesia using injectable agents is more easily accomplished compared with the use of inhalants. The induction time for injectable agents is shorter in most cases and this decreases patient stress. If the animal has an airway problem, the use of injectable agents results in a quicker way to control the airway and ensure a patent airway. Injectable agents do not pollute the atmosphere. There are disadvantages associated with the use of injectable agents. Prolonged recovery especially in agents that depend primarily on hepatic metabolism for inactivation will occur. Prolonged effects may also occur in very young and old patients. There is a possibility of hypoventilation and then hypoxemia especially in patients not supplemented with high concentration of oxygen. The depressant effects of the injectable agents cannot be reversed especially in agents without specific reversal agents. There will be a delay when attempting to lighten the depth of anesthesia if a problem arises. Maintenance of anesthesia using injectable agents can be performed by either intermittent IV or IM injections or by constant rate infusion (CRI). In this presentation, total IV anesthesia (TIVA) pertains to the administration of IV agent(s) using CRI to provide an anesthetic state. Ideally, this technique involves the use of drugs that achieve the elements of the four components of general anesthesia: amnesia (anxiolysis), autonomic areflexia, analgesia, and muscle relaxation. When performing TIVA, a CRI of drugs is preferred over the intermittent IV boluses. Using intermittent IV boluses, a constant plane of anesthesia is more difficult to achieve. The CRI of drugs results in fewer sudden hemodynamic changes, lower total amount of drug given, and more rapid recovery from anesthesia. More rapid recovery from anesthesia can be due to the ability to change the rate of infusion according to the anesthetic requirement of the patient. The major disadvantage when using an effective CRI is the cost of a precision infusion device. This device, which replaces the vaporizer in this technique, should accurately deliver the chosen dose.