A/24. Intravenous anesthetics. Perioperative medication Flashcards
Drugs need to know in this topic
thiopental
propofol
etomidate
ketamine
midazolam
dexmedetomidine
fentanyl
metoclopramide
atropine
antacid drugs
antihistamines
Pros and Cons
Advantages
∙Simple technique
∙Very rapid onset
∙Sufficiently rapid recovery
∙More pleasant for the pts
∙No irritation of the airways
Disadvantages
∙Difficult to control the depth of anesthesia
Indication
∙Induction of anesthesia
∙TIVA (total intravenous anesthesia)
∙short diagnostic or surgical procedures
Thiopental
(barbiturate)
↑GABA-A
very rapid onset
only induction
∙RR and CO↓
∙Cerebral vasoconstrictor->ICP and cerebral O2 consumption↓
∙No antidote
Propofol
∙↑GABAA
∙Na channel blocker
∙Rapid onset(30s), Short effect(5-10min)
∙Rapid recover
Ix
∙Induction and maintenance
∙No analgesic effect
∙antiemetic effect
SEs
∙Pain at injection site
∙Resp. depression
∙Hypotension
Etomidate
↑GABAA
∙Fast onset(~10s), Short effect(4-8min)
Ix
∙Induction
∙No CV and Resp depression (vs Thiopental)
SEs
∙Postoperative nausea and vomiting(PONV)
∙Pain at the injection site
∙Suppression of adrenocortical function
Ketamine
↓NMDA
Moderate duration of action
Ix
∙Dissociative anesthesia -> pt remains conscious but has marked
catatonia, analgesia, amnesia
SEs
- Cardiovascular stimulant
- Intracranial hypertension
- Emergence reactions (disorientation, excitation,
hallucination, delirium, vivid nightmares)
Midazolam
↑GABAA
∙slower onset (2-3min) and recovery
∙premedication(orally)
※Antagonist: Flumazenil(iv)
- *Ix**
- Preoperative sedation
- Induction of anesthesia
- Outpatient anesthesia (ex. Colonoscopy)
SEs
∙CV and resp depression
Dexmedetomidine
Centrally-acting α2-agonist
- Adjunct to general anesthesia
- Short-term sedation in ICU settings
- Achieves sedation with no respiratory depression
Fentanyl
Opioid μ-receptor agonist
Shorter duration than morphine
∙Primary anesthetic for CV surgery
SEs
∙Resp. depression
Perioperative agents
Anxiolytics: Benzodiazepines (midazolam, lorazepam)
- *Analgesics**: 1. Opioids (fentanyl, morphine, hydromorphone)
2. NSAID’s (ketorolac, diclofenac, meloxicam)
Antiemetics: Metoclopramide
GI protective agents: H2 blockers, PPI
Antibiotics prophylaxis: Ampicillin
Acid-suppressing agents (antacid)
Weak bases that neutralize stomach acid by reacting with protons in the lumen of the gut
Sodium bicarbonate (NaHCO3)
Magnesium hydroxide (Mg[OH]2)
Aluminum hydroxide (Al[OH]3)
Oral
Symptomatic relief of dyspepsia and
heartburn
H2-receptor antagonists (anti-histamines)
- Competitive inhibitors of H2-receptors → indirect effect on proton pump activity → decrease gastric acid secretion (mainly nocturnal acid secretion)
- No H1, autonomic or anti-motion sickness effects (compared to H1 blockers)
- Acid suppressing effect is milder compared to proton pump inhibitors
Cimetidine
- Acid peptic disease (duodenal and gastric)
- Control of Zollinger-Allison syndrome (gastrin-secreting neuroendocrine tumor)
- Gastroesophageal reflux disease (GERD)
- Stress ulcers, mucosal erosion, gastric hemorrhage in ICU patients (given IV)
Atropine
Non-selective
Muscarinic antagonists
Tertiary amine (lipid-soluble) – enter CNS
- Mydriatic and cycloplegic agent – ophthalmology
- Antispasmodic, antisecretory, antidiarrheal
- Reversal of AV-block
- Management of bradyarrhythmia (IV administration)
- Antidote for cholinesterase inhibitor toxicity
Metoclopramide
D2 dopamine receptor blockers
Central effects → potent anti-nausea and antiemetic action
Peripheral effects→ reducing this inhibitory effect results in prokinetic effect (mediated by Ach)
Oral, parenteral
- Prokinetic effect (gastric paresis)
- Anti-emetic effect (achieved only at high doses)
Side effects:
1. CNS effects: restlessness, drowsiness, insomnia, anxiety
2. Extrapyramidal symptoms (drug-induced parkinsonism)
3. Hyperprolactinemia (PRL ↑) – galactorrhea, gynecomastia,
impotence, menstrual disorders
