monitoring anesthetic depth and recovery Flashcards
(55 cards)
1
Q
what are the stages of anethesia
A
- analgesia
- delirium
- surgical stage (light, moderate, moderate/deep, deep)
- respiratory paralysis
2
Q
light anesthetic plane
A
imedes procedure from being performed
3
Q
moderate anesthetic plane
A
surgical plane
4
Q
deep anesthetic plane
A
patient at risk due to magnitude of undesirable side effects
5
Q
EEG indication of anesthetic depth
A
supplement not suplant - need to use other skills to asses depth
6
Q
how to measure response to noxious stimuli
A
somatic response
- sensory - pain
- motor - movement
autonomic reponse
- cardiovascular - increase ABP and HR
- respiratory - increase RR and TV
- sudomotor - sweating, tearing
- ocular - pupil dilation
- hormonal - stress response
7
Q
what does response to noxious stimuli depend on
A
stimulus intensity
- larger intensity = greater response
anesthetic depth
- relative anesthetic quantity within CNS
- lighter anesthetic depth = greater response
8
Q
motor indicators: movement
A
- movement = somatic response to noxious stimuli
- light plane: movement
- moderate to deep plane: no movement
- relatively objective - purposeful movement vs muscle fasciculation or reflex movement
9
Q
motor indicators: tone
A
- MOST anesthetic maintenance agents: anesthetic dept = skeletal muscle relaxation; EXCEPTION: ketamine
- extra-ocular muscles (ocular globe rotation, nystagmus)
- masticatory muscles (jaw tone)
10
Q
eye positon - light plane
A
central eye position (no rotation)
11
Q
eye position - moderate plane
A
species variability
- dog, cats, pigs: ventromedial rotation
- cattle: ventral rotation
- horse: minimal and unpredictable
- small ruminants and camelids: no rotation
12
Q
eye position - deep plane
A
central eye position
13
Q
eye position exception
A
ketamine - central eye position at all planes
14
Q
nystagmus
A
- most useful in horses
- light plane: large rapid nystagmus
- moderate to deep plane: absent
15
Q
jaw tone - light plane
A
strong
16
Q
jaw tone - moderate to deep
A
loose
17
Q
jaw tone less useful in patients with:
A
- narrow TMJ range of motion (horses, ruminants, rabbits, pigs)
- TMJ disorders
- well developed masticatory muscles (horses. ruminants. rabbits)
- large mandibular mass (horses, large ruminants)
18
Q
reflexes
A
- anesthetic depth = loss of reflexes
- palpebral reflex commonly used (species dependent, light - present, moderate/deep - absent)
- protective airway reflexes also lost under general anesthesia (gag reflexes, swallowing, coughing)
19
Q
palpebral reflex exceptions
A
species exceptions: horses and camelids
- light and moderate: present
- deep: absent
agent exception: ketamine
- light and modetate: present (all species)
- deep: absent (all species)
20
Q
cardiovascular indicators
A
anesthetic depth = cardiovascular depression
- decreased contractility and systemuc vascular resistance
- arterial blood pressure as an anesthetic depth indicator
- low blood pressure suggests TOO deep anesthetic plane
21
Q
autonomic response to noxious stimuli
cardio indicators
A
- measurable as increased ABP and HR
- autonomic responses as an anesthetic depth indicator
22
Q
blood pressure confounding factors
A
- choice of anesthetic technique and drugs
- hypoventilation, hypoxemia
- anemia, hemorrhage
- cardiovascular disease
23
Q
respiratory indicators
A
anesthetic depth = respiratory depression
- minute ventilation = RR x TV
- objective assessment (PaCO2 as depth indicator, severe hypoventilation suggests TOO deep)
- subjective assessment (visual est. - unreliable)
24
Q
autonomic response to noxious stimuli
respiratory indicators
A
- measurable as increased RR
- autonomic responses as an anesthetic depth indicator
25
respiratory confounding factors
* noxious stimuli
* hypercapnia, hypoxemia, hyperthermia
* agent dependent
* mechanical ventilation
26
response to noxious stimuli during light plane
| summary
* **movement (CAUTION)**
* severe tachycardia and hypertension
* erratic respiratory pattern (patient-ventilator dyssynchrony if on ventilator)
* sweating and tearing (HORSES0
* pupil dilation
27
response to noxious stimuli during moderate plane
| summary
* NO movement
* mild to moderate increase in BP, HR, RR
* relative myosis
28
response to noxious stimuli during deep plane
| summary
* NO movement
* minimal to absent changes in ABP, HR, RR
* pupil dilation
29
inhaled anesthetics
* anesthetic depth = PCNS (partial pressure in CNS) = PA (partial pressure in alveoli)
* end-respiratory gases closely represent that of alveolar gas (end-tidal concentration)
30
minimum alveolar concentration
measure of relative potency of inhaled anesthetics
31
limitations of MAC as a reference point
* inter-individual (& intra-individual) variability
* age, systemic disease, pregnancy
* premedication, body temp
32
when does the recovery period begin
when the procedure is finished and all anesthetic drugs have been discontinued
33
steps of recovery
* discontinue all anesthetic drugs
* move the animal to a dedicated area
* position the animal in sternal recumbency when possible to facilitate breathing
* increase O2 flow to prevent hypoxia and facilitate wash-out
* reversal?
34
when the most common time for small animals (and rabbits) to die
the recovery period
35
what are the goals of anesthetic recovery
* creating a safe and quiet environment
* maintaining cardiovascular function
* maintaining ventilatory function
* restoring or maintaining normal temperature
* providing additional analgesia
36
recovery environment
depends on:
* species
* location
* caseload
safe:
* temperature
* protection
37
recovery equipment
* oxygen supplementation
* thermal support
* induction agents
* monitoring (adequately trained personnel, patient assessment)
38
patient assessment in recovery
* cardiovascular
* respiratory
* temperature
* pain
39
monitoring cardiovascular function
* mucous membrane color and CRT
* heart rate (ECG, palpate pulses)
* blood pressure (doppler monitoring, monitoring, invasive BP)
* lactate
40
how to support cardiovascular function
* IV fluids
* positive inotropes (dobutamine, dopamine)
* vasopressors (dopamine, phenylephrine, norepinephrine)
41
respiratory monitoring
ventilation
* respiratory pattern and effort
* capnography
* air flow
* thoracic ausculation
* arterial blood gas
oxygenation
* pulse oximetry
* arterial blood gas
42
ready to extubate - dogs
* risk of aspiration
* swallowing consistently-ready to extubate
43
ready to extubate - cats
* risk of laryngospasm and tracheal trauma
* one swallow or movement
44
ready to extubate - horses
* obligate nasal breathers risk of obstruction is recovery
* extubate when standing
45
ready to extubate - ruminants
* extreme risk aspiration
* extubate when chewing and swallowing vigorously
46
procedure and patient considerations
* tracheal collapse
* pneumonia
* ventral slot
* thoracotomy
* neuromuscular blocking agents
* upper airway obstruction
47
brachycephalic breeds
* maintain ET tube until totally awake
* pre/post O2
* ready to re-intubate
* increased vagal tone
48
oxygen supplemenation
* young healthy small animals for routine procedures usually don't need supplemental O2 (hypothermia - shivering - increased O2 consumption)
* horses may supplement for increased oxygen consumption during recovery
* if N2O used during anesthesia, wash out system w/ 100% O2 for 5-10 min to prevent diffusion hypoxia
49
dysphoria/emergence delirium
* high doses of opioids (dysphoria)
* older animals
* predisposed breeds
* quick improvement w/ 1-3 mcg/kg naloxone or 0.05-0.1 mg/kg butorphanol
50
pain
* suspicion of insufficient analgesia
* improves with further analgesia
* high ABP, fR, and HR: non-specific, elevated in fear, stress, shock, during recovery from anesthesia
* VAS/DIVAS and composite pain scales
51
if no signs of pain at surgical site, consider the other sources of discomfort:
* full bladder
* constipation
* bandage pain
* joint pain from positioning during surgery
* other pre-existing source of pain (OA, pancreatitis, etc)
52
prevention and treatment of dysphoria
prevention
* minimize stimuli
treatment
* time
* consider reversal (benzodiazepines, opioids)
* consider sedation (alpha 2 agonists, ace)
53
prolonged recovery
* clearance of inhalant anesthetics (ventilation, duration of anesthesia)
* clearance of injectable anesthetics (hepatic function, renal function)
* hypothermia
* metabolic abnormalities (hypoglycemia, electrolyte disturbances)
* neurologic abnormalities
54
prolonged recovery treatment
rule out:
* hypothermia
* hypoglycemia
* abnormal electrolytes
consider reversing
* alpha-2 agonist: atipamezole, tolazoline, yohimbine
* benzodiazepines: flumazenil
* opioids: butorphanol, nalozone, naltrexone, nalbuphine
55
transfer
* patient signalment and medical condition
* anesthetic procedure
* all medications
* complications
* current status
* catheter management
* contact information
