Monitoring---Anesthesia Flashcards
3 most important parameters monitored during surgery
- Anaesthesia depth
- Cardiovascular function
- Respiratory function
Anesthesia depth is used as a guide to tell us…
if we need more or less anesthetic
What’s the best monitor?
YOU
Physical signs used to determine anesthesia depth: (8)
– Palpebral reflex – Jaw tonicity – Movement – Cornea – Heart rate – Respiratory rate – Haemodynamic/ respiratory variations -- Eye movement
During anesthesia monitoring of a horse, you notice the palpebral reflex is still present. What do you do?
Nothing! It’s normal.
During anesthesia monitoring of a dog, you notice the palpebral reflex is still present. What do you do?
Crank up the anesthesia because that’s sooooo not normal. (same for cats)
What is stage 1?
Analgesia
What are the 7 components of stage 1/analgesia?
- Stage of voluntary movement
- From beginning of induction to loss of consciousness
- Motor function present
- Euphoria
- Ataxia
- Hallucinations
- Hyperacusis
What is stage 2?
Excitement
What are the 8 components of stage 2/excitement?
• Stage of delirium or involuntary movement • From loss of consciousness to onset of regular breathing • Salivation, vomiting • Dilated pupils • Tachycardia and hypertension • Nystagmus common in horses • Laryngeal spasm in pigs and cats • Avoid stimulation
What is stage 3?
Surgical anesthesia
What are the four components of stage 3/surgical anesthesia?
• Divided in plane 1-4 OR light, medium, deep • Progressive depression of reflexes • Plane 2: – moderate surgical anaesthesia – adequate muscle relaxation – stable respiration and pulse rate – strong corneal reflex • Plane 3: deep surgical anaesthesia; desired plane when muscle relaxants were not used; pupil dilation
What is stage 4?
Asphyxia
What are the components of stage 4/asphyxia?
- ἀσφυξία: without pulse
- CNS extremely depressed
- Respiration ceases, terminal gasps possible
- Blood pressure at shock level
- Pupils widely dilated
- Without intervention: death
Let’s say you’ve induced a patient without muscle relaxants on board…what plane of stage 3 do they need to be in before you start incising?
Plane 3
Let’s say you’ve induced a patient WITH muscle relaxants on board…what plane of stage 3 do they need to be in before you start incising?
Plane 2 is ideal
You’re monitoring induction of a cat and notice laryngeal spams. Is zi cat ready to be incised? What stage is she in?
Stage 2
Monitoring a cow during surgery and you notice elevated BP. how concerned should you be?
Not toooo concerned since increased BP is somewhat normal for cattle during anesthesia.
When should you check for corneal reflex?
Only if you think the patient is dying! Otherwise, this reflex should be present throughout stages 1-3. Remember stage 4 is death’s door so we probably would see little to no corneal reflex then.
How often do we monitor?
Continuously every 5 minutes. Not just every 5 minutes but continuously, every 5 mins. There is no such thing as over doing it.
Ways to monitor cardiovascular function:
• Capillary refill time, mucous membranes • Heart rate and rhythm • Blood pressure – non-invasive vs invasive – arterial BP – central venous BP • Cardiac output
What does it mean when you can’t really feel the femoral/metatarsal pulse?
Means BP is really low.
Ways to monitor the Heart Rate
- Auscultation
- Heart palpation
- Pulse palpation
- Doppler ultrasound
- Pulse oxymeter
- Blood pressure monitor
- Electrocardiogram (ECG)
Electrocardiogram (ECG)
1) it gives no information on the mechanical function of the heart
2) doesn’t tell you anything about cardiac output
3) just don’t use this as the sole monitor for CV fxn.
So we know that ECG sucks sometimes….but how can it be misleading?
1) It can look normal even if patient is hypovolemic
2) may be normal during cardiopulmonary
arrest
3) misinterpretation
What measurement does the prof find to be more important than ECG during monitoring?
Arterial blood pressure measurement
What HR is considered bradycardia in dogs?
Under 60 bpm..still, BP is more important as HR is relative
What HR is considered bradycardia in cat?
Under 100 bpm…still, BP is more important as HR is relative
What HR is considered bradycardia in horses?
Under 20 bpm…still, BP is more important as HR is relative
Non-invasive techniques for Arterial blood pressure measurement? (2)
– Oscillometric technique
– Doppler probe
**Dont’ forget we have invasive method as well
Why is the BP important??
MAP=driving force for blood flow through capillaries that supply O2 to organs and tissue beds.
Can we measure O2 content in the blood?
Yes
Can we measure Cardiac Output?
Yes but it’s not that practical especially to do on a daily basis.
What two parameters does Cardiac Output depend on?
SV and HR.
Remember, we can measure HR no problem. But SV?…
Another card for SV.
Can we measure Stroke Volume?
It’s not that easy to measure SV…definitely not practical to do on a daily basis.
It depends on after load, preload, contractility, etc
Since measure Cardiac Output isn’t practical, what’s the closest measurement we can use to get to figuring out what the CO is?
Blood pressure! BP gives us an idea about perfusion. BP depends on CO.
With BP being the closest measurement we can get to figuring out the CO, can we always assume BP will match CO? In other words, high BP=high CO and low BP=low CO?
NO!
If you have a rather high or almost high BP and PALE mucous membranes, that means VASOCONTRICTION. This means perfusion is low because Cardiac Output is low.
Pale mucous membranes with high blood pressure…what’s going on here?
Vasoconstriction due to low cardiac output.
