General Anesthetics

Question 1

what are general anesthetics (GA)?

Answer 1

drugs that produce unconsciousness and lack of responsiveness to all painful stimuli

Question 2

what are the two groups GA can be separated into?

Answer 2

• inhalent anesthetics

- IV anesthetics

Question 3

what is the definition of analgesia?

Answer 3

loss of sensibility of pain

Question 4

what is the definition of anesthesia?

Answer 4

refers to not only the loss of pain, but to the loss of all sensations and consciousness

Question 5

what would the properties be if an ideal anesthetic existed?

Answer 5

-unconsciousness
- analgesia
- muscle relaxation
- amnesia
- adverse effects would be minimal
DOES NOT EXIST

Question 6

what is balanced anesthesia?

Answer 6

combining drugs to accomplish what we cannot achieve with an inhalation anesthetic alone

Question 7

what are the common drugs that are combined to make the ideal anesthesia?

Answer 7

• propofol and short-acting barbiturates
• neuromuscular blocking agents
• opioids and nitrous oxide

Question 8

what is the action of inhalant anesthetics?

Answer 8

enhance transmission at inhibitory synapses and by depressing transmission at excitatory synapses

Question 9

what is the action of nitrous oxide?

Answer 9

enhances GABA receptors

Question 10

what is the definition of minimum alveolar concentration (MAC)?

Answer 10

the minimum concentration of drug in alveolar air that will produce immobility in 50% of patients exposed to painful stimulus

Question 11

what does the MAC tell us?

Answer 11

approx. how much anesthesic the inspired air must contain to produce anesthesia

Question 12

what does a low MAC indicate?

Answer 12

high anesthetic potency

Question 13

in order to produce GA in all patients - what must the inspired anesthetic concentration be?

Answer 13

1.2-1.5 times the MAC

Question 14

what are the principal determinants of anesthetic concentration?

Answer 14

• uptake from the lungs

- distribution to the CNS and other tissues

Question 15

what are factors that determine the anesthetic uptake?

Answer 15

• amount inspired
• pulmonary ventilation
• solubility of the anesthetic in blood
• blood flow through the lungs

Question 16

what is distribution determined by?

Answer 16

regional blood flow

Question 17

in what tissues does anesthesia rapidly rise in?

Answer 17

brain, kidney, liver, and heart - tissues that receive the greatest amount of blood

Question 18

in what tissues is anesthesia distribution slower?

Answer 18

• skin and skeletal muscle

- fat, bone, ligaments

Question 19

where are inhaled anesthetics generally eliminated?

Answer 19

in the lungs…

Question 20

what same factors that influence uptake also influence _____?

Answer 20

elimination

Question 21

why does anesthesia leave the brain the fastest after administration has stopped?

Answer 21

because blood flow is high here - brain will wake before body

Question 22

what are 6 adverse effects of GA?

Answer 22

• respiratory and cardiac depression
• sensitization of the heart to catecholamines
• malignant hyperthermia
• aspiration of gastric contents
• hepatotoxicity
• toxicity to operating room personel

Question 23

what do almost all patients require when under GA d/t resp depression?

Answer 23

to be ventilated

Question 24

what is malignant hyperthermia?

Answer 24

• rare

- muscle rigidity and a profound elevation of temp

Question 25

what can trigger malignant hyperthermia?

Answer 25

succinylcholine - a neuromuscular blocker

Question 26

why does aspiration of gastric contents happen?

Answer 26

reflex that usually prevents this is absent

Question 27

what can aspiration of gastric contents cause?

Answer 27

bronchospasm and pneumonia

Question 28

what might be needed for aspiration?

Answer 28

endotracheal tube

Question 29

what are reactions of toxicity of OR personel?

Answer 29

headache, reduced alertness, and spontaneous abortion

Question 30

what drugs results in decreased anesthetic dosage?

Answer 30

opioids

Question 31

what drugs result in an increased anesthetic dosage?

Answer 31

CNS stimulants

Question 32

what are 3 reasons preanesthetic medications are administered?

Answer 32

- reducing anxiety - producing preoperative amnesia - relieving pre/postoperative pain

Question 33

what are alpha adrenergic agonists given for?

Answer 33

adjuncts to anesthesia - both produce effects in the CNS

Question 34

what are anticholinergic drugs given for?

Answer 34

dec. the risk of bradycardia during surgery

Question 35

what are neuromuscular blocking agents given for?

Answer 35

relaxing skeletal muscle

Question 36

why are antiemetic given postoperatively?

Answer 36

may have some nausea as recovering from anesthesia

Question 37

why are muscarinic agonists given after surgery?

Answer 37

abdominal distention and urinary retention are possible post-operative complications

Question 38

who are the only two people who can do the dosing and administration of anesthetics?

Answer 38

anesthesiologist (physician), anesthetist (nurse)

Question 39

what are the two type of inhalation anesthetics?

Answer 39

gases and volatile liquids

Question 40

what are gases?

Answer 40

exist in gaseous state at atmospheric pressure

Question 41

what are volatile liquids?

Answer 41

exist in liquid form at atmospheric pressure but can easily be volatilized (turned to vapour)

Question 42

what is isoflurane?

Answer 42

- volatile inhalation - high potency - emerge rapidly - respiratory irritant

Question 43

when do patients awake after ceasing isoflurane?

Answer 43

approx 20 min

Question 44

what is requires with isoflurane?

Answer 44

a strong analgesic and other muscle relaxant drug

Question 45

what might isoflurane inhibit during labour?

Answer 45

uterine contractions

Question 46

what are adverse effects of isoflurane?

Answer 46

- hypotension | - resp depression

Question 47

what is nitrous oxide?

Answer 47

- "laughing gas" - volatile liquid - high anesthetic potency

Question 48

is nitrous oxide ever employed as a primary anesthetic?

Answer 48

NO - impossible to produce surgical anesthesia alone

Question 49

why is nitrous oxide given?

Answer 49

to supplement the analgesic effects of the primary anesthetic

Question 50

what are adverse effects of nitrous oxide?

Answer 50

there are none - cannot cause CNS depression

Question 51

when are IV anesthetics used?

Answer 51

alone or to supplement an inhalent

Question 52

what is benzodiazepine used for?

Answer 52

to reduce anxiety and promote amnesia

Question 53

what is midazolam used for?

Answer 53

- induction of anesthesia and to produce conscious sedation

Question 54

when used for induction, what is midazolam commonly combined with?

Answer 54

barbiturate | - unconscious in 80 sec

Question 55

what is propofol?

Answer 55

- most widely ised IV anesthetic | - indicated for induction and maintenance of GA as part of balanced anesthesia technique

Question 56

what does propofol promote the release of?

Answer 56

GABA

Question 57

what is the onset of propofol?

Answer 57

less than 60 sec

Question 58

what is the duration of propofol?

Answer 58

3-5 mins

Question 59

how can extended sedation for propofol be achieved?

Answer 59

a continuous low-dose, not exceeding 4mg/kg/hour

Question 60

what does propofol put the patient at high risk for?

Answer 60

bacterial infections

Question 61

when are preoperative meds given?

Answer 61

30-60 mins before surgery

Question 62

what are nursing implications for preoperative meds?

Answer 62

- calm patient - provide analgesia - counteract adverse effects of general analgesia

Question 63

what are nursing implications for postoperative patients?

Answer 63

- know what frug they have been given in hospital | - know what drugs they are taking at home