DM1 Pt5-1 Assessing Anaesthetic Depth Flashcards
Why is it important to assess the depth of anesthesia in cats?
To ensure the cat is not under inadequate (too light) anesthesia, which can cause pain, stress, and movement during surgery, or too deep anesthesia, which increases cardiovascular and respiratory risks.
What are the stages of anesthesia during induction with an inhalant agent?
- Stage 1: Loss of consciousness
- Stage 2: Excitement phase with increased movements
- Stage 3: Adequate depth for surgery
- Stage 4: Excessive depth or overdose
What are some parameters used to assess the depth of anesthesia in cats?
- Eye position
- Presence or absence of blink reflex
- Jaw tone
- Respiratory rate
- Heart rate
- Blood pressure
- Presence of voluntary movement
How does eye position help assess anesthesia depth?
During anesthesia with inhalants or injectable agents like propofol and alfaxalone, the eyes rotate downward. If anesthesia becomes too deep, the eyes return to a central position.
What does the presence of a blink reflex indicate about anesthesia depth?
A blink reflex indicates a light plane of anesthesia, often meaning that the depth of anesthesia is inadequate for surgery.
How does jaw tone change with anesthesia depth?
Jaw tone relaxes as the depth of anesthesia increases, but the baseline jaw tone varies between animals, so comparing changes within the same patient is key.
What autonomic nervous system parameters can indicate changes in anesthesia depth?
Heart rate, blood pressure, and respiratory rate. An inadequate depth of anesthesia typically causes an increase in these parameters due to sympathetic nervous system stimulation.
Why are changes in heart rate, blood pressure, and respiratory rate considered more sensitive than eye position?
Autonomic nervous system changes (heart rate, blood pressure, respiratory rate) respond more quickly to changes in anesthesia depth than eye position, blink reflex, or jaw tone.
Why is voluntary movement during surgery a critical indicator of anesthesia depth?
Voluntary movement indicates an inadequate depth of anesthesia and can be dangerous, especially during procedures like eye surgery. Movement should be stopped quickly, typically with an IV injection of propofol or alfaxalone.
Why should information from multiple parameters be used when assessing anesthesia depth?
Relying on a single parameter can be misleading. For example, an increase in heart rate could be due to factors like blood loss or hypotension rather than light anesthesia. It’s important to assess all parameters to make an accurate judgment on anesthesia depth.
