Patient monitoring during anesthesia Flashcards
How long does sedation take
Sedation takes: 20-30 min SQ, 15 min IM, 3-5 min IV
What can affect degree of sedation
Degree of sedation depends on drugs and environment:
Quiet, dark, familiar, owner present, other animals
Brachycephalics are at constant risk of asphyxiation when sedated-monitor continuously
Animals may be more painful when sedation wears off
How long does sedation last
Duration of sedation can last up to 8 hours
may still be sedated during recovery, at time of discharge and maybe after arriving home
What to look at for signs of sedation
T: usually constant; may be slightly decreased
P: slight ↓; severe decrease if α-2 agonist
R: slight ↓; may pant if hydromorphone (dog)
Prolapsed 3rdeyelid
Pupil size – same or relative miosis
Ataxia – mild to severe, to recumbent
Check for muscle rigidity, twitches
GI – v/d possible, ↑ saliva
What are some unacceptable signs of sedation
TPR
increase temp
sudden onset murmurs or arrhythmias
severe bradycardia (need to check BP)
MM – cyanosis or very pale
Abnormal nystagmus
http://www.youtube.com/watch?v=zLZJvqKhQBU
Blood or foreign object in vomit or diarrhea
Tremors, seizures
Weakness, stupor, unconsciousness; inability to arouse
When does induction begin and what is it
Induction begins with administration of induction agent
Goal is entry into stage 3 plane 1
Watching for changes consistent with stage 1 voluntary excitement → stage 2 involuntary excitement → stage 3, plane 1 light anesthesia
What does stage 1 look like in the animal
Stage 1: open mouth breathing, irregular depth of respiration, saliva, redness of eyes (conjunctivitis), +TPR (from fighting)
What does stage 2 look like int eh animal
Stage 2: vocalizing, tremors, twitching, paddling, rigidity
What does the animal look like while in stage 3
relaxed and recumbent
What affects the rate of induction
Faster with injectable vs mask induction
Minimal difference b/w injectables
Why monitor while under GA
Monitor for safety and monitor for anesthetic depth
Monitoring is manual (by the person) and machines are backup only
Monitor 2 parameters
Patient stability
Anesthetic depth
Anesthetic always have side effects
Purpose of monitoring is to warn early about changes in anesthetic depth and patient condition
Healthy patients are at risk; risk increases with increasing PS score
Drug selection, drug dose and duration of GA will also affect stability and depth
Risks include cardiac arrest, pulmonary arrest, brain stem depression, coma, vasogenic/cardiogenic/hypovolemic shock, drug reactions
What should you monitor while inducing
Continue to monitor heart rate and resp function, mm colour
Easy to forget when setting up monitoring equipment and intubation
Watch chest rise/fall
Check with auscultation
Minimum monitoring parameters while under GA are
HR and rhythm
Rate and depth of respiration
Mm colour, CRT
Pulse strength
BP (minimum is systolic)
*C
What are some additional monitoring that are nice to have but not needed while under GA
Diastolic, MAP, arterial BP
Oxygen saturation (SpO2)
End tidal CO2
ECG
How do you monitor for anesthetic depth while under GA
By monitoring vitals
Should remain stable
Decrease in HR< RR, BP, indicate problems
By monitoring muscle tone and reflexes
Includes eye position, pupil size, jaw tone, limb flaccidity
Goal is to find balance between sufficient anesthesia to block sensation of pain while allowing for procedure
When should you be monitoring patients under GA
Starts from the time of induction
Monitor a minimum of q5min if P1 or P2
Monitor continuously if P3 or above
Monitor continuously if a horse on inhalants or 45+ min of GA
Once patent has recovered q15min until patient can sit or lay in sternal and TPR has returned to preanesthetic values
What are some important factors when monitoring under GA
Monitoring requires manual verification of machine data and hands on check of the patient
Look at anesthetic machine: O2 flow, vaporizer, bag, pop-off valve, pressure gauges
Record O2 flow and %gas
When does stage 1 of anesthesia happen
Stage 1 occurs after giving the general anesthetic drug (proper pre- med/sedation should NEVER result in Stage 1)
Goal: to move through Stage 1 as fast as possible
End of Stage I: Can’t stand → recumbent (make sure body is properly supported)
What are the physiological responses while under stage 1 of GA
Still conscious but losing consciousness towards end)
Fear, excitement, disorientation, struggling
↑HR, ↑RR
Panting, urination, defecation
Pupil dilation
Patient is difficult to handle
What are the physiological responses while under stage 2 of GA
Unconscious
Involuntary movement (twitching, paddling, rigid muscles), moaning or other vocalization, urination/defecation
Pupils dilated
Muscle tone and reflexes present or slightly exaggerated
↑HR (should never see arrhythmia)
↑RR, irregular breathing, may be open-mouth (never cyanotic)
What does stage 2 of anesthesia look like
Patient is in unconscious “flight or flight”
Goal: to move through Stage 2 as fast as possible
End of Stage II: Muscles relax, slowing down of HR/RR, decreasing reflexes
What does stage 3 plane 1 look like under GA
Goal when inducing; time to intubate; fine for prep and moving patient; not sufficient for most surgical procedures
Unconscious
Muscles are relaxed but still have tone: limbs relaxed
Decreased jaw tone (some tone, but can easily open + close)
Decreasing reflexes
Slow PLR/palpebral/pedal (aka withdrawal)
Decreased gag/swallow → can pass ETT; start on inhalant
Decreased cardiopulmonary fxn:
Mild ↓ HR, RR, °C, BP; breathing is regular
Pupils: constricted, centrally located
Loss of tear production (need to apply an eye lubricant)
What does stage 3 plane 2 look like
Appropriate stage for cutting and painful procedures
Signs are same as Plane 1, except for these changes:
Pupils less constricted, eyes ventromedial (D,C; but not H)
No swallow/gag/palpebral/pedal
Decreased muscle tone - limbs are relaxed but not flaccid
HR, RR, BP slight decrease from Plane 1 but steady and stable
Mm still pink, CRT <2
Will continue to drop temp
What should some surgical stimulus cause
Certain surgical stimulation SHOULD cause:
Mild ↑HR, mild ↑RR, ↑BP
Patient remains unconscious and immobile
What does stage 3 plane 3 look like while under GA
Excessive CNS depression; significant cardiovascular and pulmonary depression
NO response to surgical stimulation
Decreasing HR/RR/BP; approaching minimal cut-offs
Decreased tidal volume (decrease oxygen, increasing CO2)
Low pulse strength, prolonged CRT, pale mm
Pupils moderately dilated, centrally located
Muscles are flaccid (NO jaw tone, limp)
What should you do if you notice the patient is in stage 3 plane 3
WARNING patient not stable
Decrease anesthetic
Likely requires manual ventilation (aka “start bagging”)
What does stage 4 of GA look like
BAD! Marked depression of the CNS
Pupils completely dilated, eyes centrally located
ALL reflexes absent
All muscles paralyzed or flaccid
Cardiovascular and respiratory collapse = SHOCK
VERY brief, transient sympathetic response; followed by rapidly dropping vital signs
Rapidly decreasing HR, RR, BP
Prolonged CRT, MM – pale or cyanotic
Death in 1-5 min if do nothing
How often should you monitor cat and dogs
Minimum every 5 min for P1, P2
Continuous if P3 or higher
How often should you monitor horses and exotics under GA
Continuous if on inhalants
Continuous if more than 45 min
