Introduction

Question 1

What is anesthesia

Answer 1

Drug induced reversible CNS depression

• loss of response and perception of external stimuli
• low therapeutic index
• combines pharmacology, physiology, clin path, medicine, surgery

Question 2

Anesthetic

Answer 2

Compound or element that by itself can produce general anesthesia
- ex: isoflurane, propofol, alfaxalone

Question 3

Anesthesia

Answer 3

State achieved by combination of agents, none of which alone produces anesthesia
- ex: combo of alpha2-agnoist, opioid, dissociative

Question 4

Anesthetic agents are used for

Answer 4

• exam
• diagnostics
• surgery
• seizure control
• euthanasia

Question 5

Anesthetic agents are administered

Answer 5

• IV, IM, SC, IN
• inhaled
• topically
• epidural
• subarachnoid
• infiltration

Question 6

Inhaled anesthetics

Answer 6

• volatile hydrocarbons
• noble gases
• carbon dioxide
• nitrous oxide

Question 7

Injectable anesthetics

Answer 7

• barbiturates
• chloral hydrate/chloralose
• imidazoles
• phenolics
• steroids
• benzodiazepines
• cyclohexamines
• Na+ channel blockers

Question 8

Where do anesthetics work?

Answer 8

Subcellular target is synaptic function via ligand-gated ion channels

• n-methyl-d-aspartate (NMDA) antagonists –> dissociatives (ketamine_
• gamma aminoibutyric acid (GABA) agnoists –> inhalants

Question 9

_______ is primary site where anesthetics act to inhibit purposeful responses

Answer 9

Spinal cord

- brainstem, cerebral cortex involved in conscious perception and memroy

Question 10

What are the 4 components of general anesthesia

Answer 10

• amnesia
• unconsciousness
• immobility (dose-dependent)
• analgesia: attenuation of autonomic responses to noxious stimuli

Question 11

Unresponsiveness _____ unconsciousness

Answer 11

Does NOT equal to!!

Question 12

Consciousness

Answer 12

Subjective experience

Question 13

Connectedness

Answer 13

Awareness of the environment

Question 14

Responsiveness

Answer 14

Spontaneous or goal-directed movement

Question 15

____ likely depends on integrity of the corticothalamic networks

Answer 15

Consciousness

Question 16

Spontaneous _______ may depend on subcortical and spinal cord networks

Answer 16

Responsiveness

Question 17

______ may depend on continued information integration in corticothalamic circuits and unperturbed norepinephrinergic signaling

Answer 17

Connectedness

Question 18

What takes the highest anesthetic concentration to block?

Answer 18

Blocked autonomic response

Question 19

Loss of righting reflex associated with onset of unconsciousness is _____

Answer 19

Drug dependent

- memory and awareness ablated at anesthetic concentration <50% of that needed to abolish movement

Question 20

Anesthetized animals may move in response to ______

Answer 20

Noxious stimuli

• unconscious animals can produce complex movements at the level of the brainstem or spinal cord
• connection to cerebral cortex not required

Question 21

Pain

Answer 21

Unpleasant sensory and emotional experience associated with actual or potential tissue injury

• conscious awreness of nociception
• response to nociception

Question 22

Nociception

Answer 22

Activation of nociceptors by noxious stimulus

Question 23

Analgesia is absence of _____

Answer 23

Pain

- pain is a conscious experience

Question 24

Anesthetized patients ____ experience pain

Answer 24

Do Not

• may respond physiologically, autonomically and reflexively to noxious stimuli
• supplemental analgesia useful to reduce anesthetic requirement, improve comfort at recovery

Question 25

Analgesia

Answer 25

- conscious: reduced pain perception | - unconscious: reduced autonomic response to nociception

Question 26

Preventive analgesia

Answer 26

Use analgesic drugs and techniques before, during, and after pain begins - prevents plastic wind up of pain pathways

Question 27

Anesthetic care plan

Answer 27

Meets unique medical needs of the individual patient - consists of patient evaluation and patient preparation - informed anesthetic choices

Question 28

Anesthetic sequence of events

Answer 28

- preanesthetic evaluation, preparation, medication - anesthetic induction - maintenance of anesthesia - recovery phase (24 hr following awakening)

Question 29

50% of anesthetic deaths occur ______

Answer 29

Post-op

Question 30

Patient evaluation

Answer 30

- positive patient identification - history - physical exam findings - lab data

Question 31

Lab tests should be chosen based on ________

Answer 31

Physical exam and history | - extensive non-directed pre-anesthetic lab screening does not improve patient outcome!!

Question 32

ASA status assignment

Answer 32

- class 1: no systemic dz - class 2: mild compensated systemic dz - class 3: serious systemic dz, stable vital signs - class 4: serious systemic dz, decompensated - class 5: moribund, requires intensive life support

Question 33

Why hospitalize patient overnight?

Answer 33

- acclimatize to clinic - time for evaluation - time for stabilization, if needed

Question 34

Fasting

Answer 34

May decrease aspiration risk - improves abdominal access - may improve ventilatory function - species differences - not recommended in young patients

Question 35

Monogastrics vs ruminants

Answer 35

- monogastrics: water access up to time of premedication | - ruminants: usually recommended (associated with increased parasympathetic tone)

Question 36

Patient stabilization

Answer 36

Very important! - provide analgesia - treat blood, fluid, or electrolyte deficits ahead of time - decreases anesthetic risk

Question 37

Equipment

Answer 37

- venous catheterization - fluid therapy - patient monitoring - materials for treatment of anticipated complications (anesthetic and surgical) - induction and maintenance

Question 38

Awake EEG

Answer 38

- low voltage ampllitude | - many high frequency components (fast) --> desenchronized

Question 39

Deep anesthesia EEG

Answer 39

- higher voltage - slow oscillations - synchronized, dose dependent

Question 40

EEG does not determine _______

Answer 40

Onset of consciousness - limited ability to indicate presence or absense of unconsciousness around the transition point - unclear which patterns are indicators of activation by stress or pain

Question 41

Wakefulness

Answer 41

State of being awake - implies brain physiological state that differs from that found with sleep or anesthesia - does not by itself signify presence of consciousness