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Anesthesia Pharm I > Premedication > Flashcards

Flashcards in Premedication Deck (29)
1

what are goals of premedication?

-reduce anxiety, amnesia
-pain relief
-sedation
-reduce risk of aspiration
-nausea and vomiting prophylaxis
-antisialagogue
-reduce MAC
-prophylaxis of allergic reaction

2

what is the MOA of benzodiazepines?

-sedation produced by intensification of GABA effects
-anxiolysis produced by glycine-mediated inhibitory effect on neuronal pathways in the brain

3

what are the advantages of benzos?

-sedation
-anxiolysis
-amnesia
-minimal effects on ventilation and cardiovascular
-raise seizure threshold
-reduce MAC

4

what are disadvantages of benzos?

-no analgesia (must consider whether pain med is needed more in preop)
-possible paradoxical reaction (confusion, agitation)
-implicated as teratogenic during first trimester (cleft lip)

5

what is the MOA of droperidol (Inapsine)?

antagonizes the activation of dopamine receptors, interferes with transmission mediated by serotonin, NE, GABA; also alpha-adrenergic blocker

6

what are effects of droperidol?

-outward appearance of calm
-dysphoria, restlessness, fear of death
-antiemetic effects

7

what is the MOA of opioids?

bind to specific receptors throughout the central nervous system, tissues

8

what are the advantages of opioids?

-no direct myocardial depression
-pre-emptive analgesia
-analgesia in pre-existing pain, painful procedures
-decreases incidence of increased HR during surgical procedure

9

what are disadvantages of opioids?

-depresses ventilation, particularly RR; apneic threshold elevated; hypoxic drive decreased (not good w/ sleep apnea)
-orthostatic hypotension
-N/V
-no amnestic effect
-sphincter of Oddi spasm
-dysphoria in patients without pain
-histamine release

10

describe morphine

-well absorbed IM
-histamine release
-may cause orthostatic hypotension, pruritus, respiratory depression
-dose 0.1-0.2 mg/kg IM (15-30 min)

11

describe fentanyl

-about 100x more potent than morphine
-usually given just prior to induction
-5-8 mcg/kg blunts response to laryngoscopy
-most commonly used opioid in anesthesia
*dose IV 1-2 mcg/kg (30-60 sec) last about 30 min to an hour

12

describe NSAIDS

-given to reduce the amount of opioids required postop
*pre-emptive analgesia
-beware: prostaglandin inhibition may decrease platelet aggregation
-caution: elderly, h/o gastric ulcers, renal impairment
*decision to give must involve surgeon
*acetaminophen contraindicated w/ hepatic impairment

13

describe antihistamines

-H1 antagonist given to pts. with h/o chronic atopy or at risk for allergic reaction
*give along with a H2 antagonist
-Benadryl dose: 0.5-1 mg/kg PO

14

describe alpha 2 agonist clonidine

-centrally acting alpha 2 agonist which blunts the autonomic nervous system reflex responses to surgical stimulation (such as increased HR and BP)
*can decrease anesthetic requirement, decrease MAC
*potential for bradycardia and hypotension- give fluids
dose: 5 mcg/kg PO (90 min)

15

describe anticholinergics

-historical use
advantages: vagolytic effect, antisialogue effect (turning prone), sedation and amnesia (atropine/scopolamine cross BBB)
disadvantages: central anticholinergic syndrome, mydriasis and cycloplegia (caution w/ glaucoma), tachycardia and arrhythmias (don't give to CAD pts.)

16

which anticholinergics are best for increase in HR, antisialogue effects, and sedation?

-atropine increase in HR (give to infants 6 months or <)
-scopolamine best for sedation
-glycopyrrolate best antisialogue effect

17

what are the different types of antiemetics

-GI prokinetics (metoclopramide)
-butyrophenones (droperidol)
-phenothiazines (promethazine)
-serotonin receptor antagonists (Zofran)
-corticosteroids

18

what are the goals to prevent aspiration?

-gastric pH > 2.5
-gastric volume < 25 ml

19

how do H2 antagonist provide prophylaxis against aspiration?

-increase the pH of whatever is released in the stomach from the time medicine takes effect
-takes time to change pH of contents already in stomach since that must be diluted over time
**does not change volume
**need to receive the night before and morning of

20

what are different histamine2 receptor antagonists?

-ranitidine (Zantac)
dose: 150-300 mg PO; 50 mg IV
onset: 60-90 min
duration: up to 9 hrs

-famotidine (Pepcid)
dose: 20-40 mg PO; 20 mg IV
onset: 60-90 min
duration: 10-12 hrs

21

how does gastrokinetic agents (metoclopramide) provide prophylaxis against aspiration?

enhances the effects of ACh on the intestinal smooth muscle to :
1) speed gastric emptying
2) increase lower esophageal sphincter tone
3)relax the pylorus and duodenum
4)lower gastric volume
*does not effect gastric pH

22

what is the antiemetic effect of metoclopramide?

dopamine antagonist in the CTZ of the CNS

23

what is the dose and onset of metoclopramide?

PO 10-15 mg (30-60 min)
IV 10 mg (15-30 min)
peds: 0.25 mg/kg

24

what are contraindications of metoclopramide use?

-intestinal obstructions
-Parkinson's disease (dopamine blockage)
*push slow (potential for extrapyramidal effects; often r/t tardive dyskinesia

25

describe antacids

raises the gastric pH of fluid already present in the stomach by neutralizing the hydrogen ions with a base
*disadvantage: increases volume
*use a nonparticulate (non colored, no Mylanta) like sodium citrate (Bicitra)
*seen often in L&D; always prepare as if you may intubate

26

what is the dose of sodium citrate?

15-30 ml PO (15-30 min)

27

describe proton pump inhibitors

-most effective in controlling gastric acidity and volume
-limits the last step in secretion of hydrogen ions: hydrogen-potassium ATPase
*clinical use in moderate to severe GERD
*takes daily admin over 5 days to inhibit secretion 66%
*better than H2 blockers in inhibiting secretion, healing duodenal and gastric ulcers, and treating reflux esophagitis

28

what is the dose of omeprazole (Prilosec)?

20mg PO (single dose takes > 3 hrs to increase pH)

29

describe pediatric anxiolysis

-preop includes parents, patient, visual aids
-empower by allowing to bring toy, blanket, source of security
-explain as you go, allow to help, distract
-reduce anxiety, sedate, provide amnesia
*indicated for 6 mths and older
-oral, nasal, or rectal
-versed- PO
-methohexital- PR
-ketamine- IM