마취 유도 및 유지
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Q1: What are the four stages of anesthesia in rodents?
Stage one involves an increasing pain threshold with minimal behavioral changes. Stage two is characterized by disorientation and irregular breathing. Stage three, the surgical stage, has four planes where the animal progresses from loss of righting reflex to complete anesthesia suitable for surgery. Stage four represents overdose with complete paralysis, potentially leading to respiratory arrest and death.
Q2: How should you prepare equipment before inducing anesthesia with an inhalant anesthetic?
First, fill the precision vaporizer with appropriate liquid anesthetic. Check the waste gas scavenging system canister by weighing it; replace if it has increased fifty grams above starting weight. Assemble the induction chamber ensuring input connects from the vaporizer and output connects to the scavenging system. Verify all connections are secure before placing the animal in the chamber.
Q3: What is the preferred method for inducing anesthesia in rodents?
The preferred method is induction in a precision vaporizer-connected chamber at 3-5% isoflurane with 1 liter per minute oxygen flow. After the animal is fully anesthetized, flush the chamber with oxygen by turning off isoflurane before gently removing the animal. This reduces personnel exposure to anesthetic gases compared to using a nose cone or facemask, which animals may resist.
Q4: How do you assess anesthetic depth during a surgical procedure?
Assess anesthetic depth every 10-15 minutes using physical methods like toe pinch, tail pinch, or pinna pinch to check for withdrawal reflexes. Also evaluate the palpebral reflex by touching the medial canthus and the corneal reflex by touching the cornea. Monitor physiological indicators including heart rate, respiratory rate, blood pressure, mucous membrane color, and capillary refill time, which should not exceed 1-2 seconds.
Q5: What factors determine which anesthetic to use for a rodent procedure?
The choice of anesthetic depends on the extent and duration of the procedure, the species and strain, the animal's age, and its physiological status. Accurate body weight measurement is essential before anesthesia to ensure appropriate dose calculation, minimize overdose risk, and support animal welfare. Injectable anesthetics like ketamine combined with sedatives or muscle relaxers offer alternatives to inhalant compounds like isoflurane.
Q6: Why is thermal support necessary during rodent anesthesia?
Rodents are prone to hypothermia during anesthesia lasting longer than five minutes. Controlled thermal support is required to maintain body temperature and prevent overheating. Hypothermia can complicate recovery and compromise animal welfare. Temperature monitoring and appropriate heating devices should be used throughout the anesthetic procedure to maintain normal body temperature.
Q7: What should you do after anesthesia to ensure proper animal recovery?
Animals should recover in a controlled environment with thermal support and appropriate analgesia. Monitor animals continuously until they regain sternal recumbency, normal respiratory function, and appropriate responsiveness. Only fully recovered animals should be returned to their housing. Animals showing anesthetic complications like respiratory depression or delayed recovery require immediate humane intervention and veterinary consultation.