Drugs for Local and General Anesthesia

Question 1

what is general anesthesia?

Answer 1

• a loss of sensation/movement throughout the body, accompanied by a loss of consciousness

Question 2

what is local anesthesia

Answer 2

• a loss of sensation to a limited body region, with no loss of consciousness

Question 3

what is regional anesthesia

Answer 3

• a loss of sensation to a larger body area, with no loss of consciousness

Question 4

what is monitored anesthesia care?

Answer 4

• sedation; client remains responsive

- used during diagnostic procedures, or in combination with local anesthesia for minor surgeries

Question 5

what are the 5 routes of administration ?

Answer 5

• topical, infiltration, nerve block, spinal, epidural

Question 6

topical?

Answer 6

• applied to mucus membranes including the eyes, lips, and gums
• creams, sprays, drops, suppositories

Question 7

infiltration ?

Answer 7

• drug is diffused into tissue to block a specific group of nerves in a small area close to the surgical site

Question 8

nerve block?

Answer 8

-drug affects nerve bundles serving the surgical area, used to block sensation in a limb or larger area of the face

Question 9

what is spinal administration? where is it injected to?

Answer 9

• drug affects large, regional area such as the lower abdomen and legs
• injection into the CSF

Question 10

where is an epidural administered?

Answer 10

• used in obstetrics during labour and delivery

- injection into the epidural space of the spinal cord

Question 11

what are the mechanisms of action for local anesthetics?

Answer 11

• block voltage-gate sodium channels
• inhibit motor and sensory neuronal signalling
• bind to open sodium channels
• active neurons are most susceptible

Question 12

to improve duration of action, local anesthetics are sometimes co-administered with what & why?

Answer 12

• epinephrine

- causes vasoconstriction so the local anesthetic cannot leave the area and therefore is metabolized

Question 13

ester anesthetics

Answer 13

• rapidly metabolized in the bloodstream
• short half-life of 1 to 2 minutes
• pKa ranges from 8.6-8.9

Question 14

amide anesthetics

Answer 14

• metabolized in the liver
• longer half-life of 60 to 240 minutes
• pKa ranges from 7.5-8.0

Question 15

what form of anesthesia is an epidural? where is it administered?

Answer 15

• a form of regional anesthesia

- injection of drug into fat-filled epidural space

Question 16

What is the mechanism of action for an epidural?

Answer 16

• exerts an effect on any nerve that comes into contact with the drug
• some drug will diffuse into the arachnoid space

Question 17

what form of anesthesia is intrathecal anesthesia? where is it administered?

Answer 17

• a form of regional anesthesia
• injection of a local anesthetic directly into CSF
• administered: surgical scheduled procedure, rarely used during labour

Question 18

rate of efficacy between epidural and intrathecal anesthetics

Answer 18

• intrathecal has a higher rate of efficacy compared to epidural, requires less anesthetic than epidural

Question 19

how are opioids used in regional anesthesia?

Answer 19

• administered in the epidural space
• bind to presynaptic receptors in the substantial gelatinosa, inhibiting the release of pain signalling neurotransmitters in the spinal cord
• bind to postsynaptic receptors in the brain decreasing neuronal excitability

Question 20

do opioids have an effect on motor neurons?

Answer 20

• no: mobility, proprioception, and sense of touch are maintained

Question 21

what kind of pain do opioids control?

Answer 21

-visceral pain

Question 22

what are some adverse effects of opioids?

Answer 22

• itchiness
• nausea and vomiting
• respiratory depression

Question 23

what are some adverse effects of spinal and epidural anesthesia?

Answer 23

• backache
• infection
• inadequate anesthesia
• arachnoiditis
• spinal headache

Question 24

what are the four stages of general anesthesia?

Answer 24

1. analgesia
2. disinhibition
3. surgical anesthesia
4. medullary depression

Question 25

step 1: analgesia

Answer 25

- loss of pain; client loses general sensation but may be awake

Question 26

step 2: disinhibition

Answer 26

- excitement and hyperactivity; patient may be delirious and try to resist treatment. - heart rate and breathing may become irregular and blood pressure may increase

Question 27

stage 3: surgical anesthesia

Answer 27

- skeletal muscle becomes relaxed and delirium stabilizes | - cardiovascular and breathing activities stabilize, eye movements slow and the patient becomes still

Question 28

stage 4: medullary depression

Answer 28

- paralysis of the medulla region in the brain

Question 29

what is intravenous anesthesia co-administerd with and what does it induce?

Answer 29

- co administered with inhaled general anesthetics once the client loses consciousness - induces analgesia, sedation, muscle relaxation, and LOC

Question 30

mechanism of action of inhaled general anesthetics

Answer 30

- prevent flow of sodium ions into neurons in the CNS, reducing neuronal activity

Question 31

gaseous inhaled anesthetics (nitrous oxide)

Answer 31

- high minimum alveolar concentration, but strong analgesic properties - used in dental procedures, during labour

Question 32

volatile liquids (isoflurane)

Answer 32

- low mean alveolar concentration to be knocked out, poor analgesic properties

Question 33

what should patients be monitored for post-op?

Answer 33

- nausea/vomiting - CNS depression - resp depression - changes in vital signs

Question 34

what drugs are available for patient pre-op?

Answer 34

- benzodiazepines: anti-anxiety and mild sedative effects - anticholinergics: dry resp and oral secretions - histamine (H2) receptor antagonists: decrease gastric fluid volume

Question 35

what drugs are available for patients during surgery?

Answer 35

- neuromuscular blockers: induce relaxation of skeletal muscle

Question 36

what drugs are available for patient post-op?

Answer 36

- pain management: opioids and NSAIDS - antiemetics: reduce nausea and vomiting associated with anesthesia - cholinergic: stimulate smooth muscle contraction in the GI tract and bladder to induce peristalsis and urination

Question 37

the purpose of general anesthesia is to induce..

Answer 37

- analgesia - sedation - relaxation - hypnosis - amnesia - loss of reflexes

Question 38

what is balanced anesthesia?

Answer 38

-no single drug can safely accomplish all 6 effects , thus balanced anesthesia is used

Question 39

what drugs classes are used in balanced anesthesia?

Answer 39

- neuromuscular blockers, short acting benzodiazepines, opioids, and general anesthetics