Lecture 5: Monitoring depth Flashcards
What is general anesthesia?
- Both the loss of consciousness and sensation
- Should include muscle relaxation, analgesia, suppression of stress response and hypnosis
- Reversible process
- May be produced with 1 drug or a combination of drugs
Describe stage 1 of anesthesia
- The time from the start of administration of induction drugs until loss of consciousness
- Stage of voluntary movement
- Most variable stage
Describe stage 2 of anesthesia
Stage of delirium and involuntary movement and lasts from loss of consciousness to onset of regular breathing pattern
In stage 2, the patient may display what symptoms?
- Struggling or exaggerated reaction to stimuli
- Vomiting or regurgitation
- Laryngospasm
- Dilated pupils
Describe stage 3 of anesthesia
Stage of surgical anesthesia due to level of unconsciousness with progressive depression of reflexes, muscle relaxation and slow, regular breathing pattern
Describe stage 3 plane 1 of anesthesia
-“light” plane of anesthesia
- persists until eyeball movement stops
- minimally invasive/painful procedures
Describe stage 3 plane 2 of anesthesia
- “medium” plane of anesthesia
- Most surgical procedures performed here
- Progressive intercostal paralysis
- Respiration and HR have stabilized
- Strong corneal reflex
- Adequate muscle relaxation and analgesia
Describe stage 3 plane 3 of anesthesia
-“deep” plane of anesthesia
- Decrease in HR
- Slow, shallow abdominal breathing pattern
- No jaw tone
- No reaction to surgical stimulation, profound muscle relaxation
- No palpebral reflex, weak corneal reflex
Describe stage 3 plane 4 of anesthesia
- pupils dilated
- slow CRT
- slow, irregular respirations
- lack of muscle tone
- no anal sphincter tone
- anesthetic overdose
What are the ocular signs to check when monitoring anesthetic depth?
- Palpebral reflex
- Eye position
- Lacrimation
- Nystagmus
- Corneal reflex
What is the goal for a surgical anesthesia plane?
- relaxed jaw tone
- mild to no palpebral reflex
- ventral medial eye rotation
- relaxed anal tone
- smooth, regular respiratory pattern
- normal heart rate
- no swallowing, coughing, vomiting, or laryngospasm
What are some specific signs in horses to look for with anesthesia?
They will lacrimate in light stages, the eye may stay central instead of ventral medial eye rotation, nystagmus in stage 2, and corneal reflex persists into deeper anesthesia plane
What are some specific signs to look for in cats with anesthesia?
May go into laryngospasm and/or may retain cough, swallow, and vomiting reflex until they reach a deeper plane of anesthesia
What is the most common factor that makes it difficult to monitor anesthetic depth?
Drugs
How does ketamine make monitoring anesthetic depth difficult?
Typical eye signs not produced, maintains more of an ‘active’ eye
How does propofol make monitoring anesthetic depth difficult?
No analgesia, apnea if given too fast
How do patients recover from anesthesia?
Progresses in the reverse order
What stage is often difficult due to delirium/dysphoria in horses?
Stage 2, for recovery
