General anesthesia (components) Flashcards
The time immediately preceding anesthesia in which
patient data are collected,
the patient is fasted
adequate hydration ensured, &
preanesthetic drugs are given.
- Preanesthesia
The process by which the animal leaves the normal conscious state and enters an unconscious state.
Usually initiated only after the animal has received premedication drugs and enough time has lapsed for these drugs to take effect.
Has (3) methods of injection
- Induction
[Method of induction] — a. Injection
Rapidly and safely pass through the first two stages of anesthesia and reach a depth that allows endotracheal intubation without resistance
Duration of anesthesia is usually less than 20 minutes.
Bolus IV
[Method of induction] — a. Injection
A dose of the agent necessary to maintain anesthesia for the entire surgical period is drawn into a large syringe and placed in a syringe pump.
After an induction bolus is given, the contents of the syringe are gradually expelled by the pump into a tube connected to an IV catheter. The drug is infused at a constant rate that maintains the correct anesthetic depth.
Constant rate infusion (CRI)
[Method of induction] — a. Injection
– useful for animals in which IV injection or mask induction is difficult
- For most agents, the anesthesia dose required for induction is 2-3 times the IV induction dose.
- The dose cannot be titrated or “given to effect”.
- Relatively slow onset of anesthesia compared with IV induction
- Lengthy recovery period.
Intramuscular
[Method of induction]
Not used routinely but may be appropriate in some situations.
b. Oral administration
[Method of induction]
Gas anesthetic delivered by a mask or anesthetic chamber.
Induction is much more gradual than IV induction
c. Inhalation
The time during which sufficient anesthetic is supplied to keep the patient at an appropriate depth of anesthesia.
When surgery and other procedures are commonly performed.
Requires close monitoring
- Maintenance
Begins when the concentration of anesthesia in the brain begins to decrease.
Reflex activity, muscle tone and sensitivity to pain are regained as consciousness returns.
The method by which an anesthetic is eliminated from the brain and circulatory system varies according to the anesthetic agent:
- Recovery
Recovery (Anesthetic agents):
Most injectable drugs are removed and metabolized from the blood by the a) ______ and metabolites are excreted by the b.) ______ system.
a) liver
b) urinary system
Recovery (Anesthetic agents):
Drug of cats that are not metabolized and excreted unchanged by the kidneys.
Ketamine
Recovery (Anesthetic agents):
The level of anesthetic in the brain falls as the drug is
redistributed to other tissues, especially muscle and fat
—> lower levels of anesthetic in the brain and arousal of the patient even though the drug is still present in the body.
short-acting barbiturates
Recovery (Anesthetic agents):
Eliminated mainly through the respiratory tract.
Brain —> blood —> lung alveoli —> exhaled
inhalation agents
Recovery (Anesthetic agents):
Administration of this agent (e.g., doxapram) and specific reversing agents hastens recovery from either inhalation and injectable anesthesia.
Analeptic agent (doxapram)
Anesthetic regimen:
(4) Pre-anesthetic agents
- Anticholinergics
- Tranquilizers, neuroleptics, ataractics
- Opioids
- Neuroleptanalgesics
