Anesthestic Drugs Flashcards
Groups of anaest drugs
Induction agent
- Inhalation -> Volatile agent & Gas: Volatile agent: sevoflurane, desflurane, isoflurane, halothane, enflurane
Gas: nitrous oxide
- Intravenous drugs: propofol, ketamine, thiopentone
Local anest: lignocaine, bupivacaine, cocaine
Muscle relaxant: suxamethonium, rocuronium, atracurium
Analgesic: fentanyl, morphine, nsaid, paracetamol
Indication of volatile agent/gas
- children (uncooperative, needle phobia)
- no IV access
- airway compromised
Factors affecting uptake of anaes into the tissue
- solubility (blood to gas partition coefficient): high blood to gas partition coefficient, high uptake of gas into blood
- tissue blood flow: the greater the blood flow, the faster the uptake
What is minimum alveolar concentration (MAC) and acceptable range
Minimum gas concentration needed to anaesthetized 50% of patient
- high MAC, low potency
- acceptable range: around 0.8
Factors affecting MAC
Higher MAC needed in
- hyperthermia
- chronic opioid use (tolerance)
- chronic alcohol intake (tolerance)
- steroid usage
Lower MAC needed in
- neonate
- acute alcohol and opioid intake
- hypothermia
- pregnancy
- anemia/hypotension
- hypothyroidism
Common volatile agents
- nitrous oxide
- sevoflurane
- desflurane
- isoflurane
Nitrous oxide
- Indication
- S/E
- MAC
- describe/criteria
Indication: use as analgesic ONLY (ethonox in O&G), use as adjuvant to lower the MAC of volatile agent
S/E: respiratory depression, mild teratogen esp used in pregnancy during organogenesis, PONV
Describe/criteria:
- colourless, odourless, non explosive
- potent analgesic but weak anaesthetic
Sevoflurane
- indication
- s/e
- mac
- describe/criteria
Indication: for rapid induction and maintenance, and rapid recovery
Rapid S/E: mild effect on bp/hr, respiratory depression (decrease tidal volume, increase RR), bronchodilation
Mac: 2.0
Describe: sweet smell (can be used in paeds and adult)
Desflurane
- indication
- s/e
- mac
- describe/criteria
Indication: for maintenance (rapid onset and rapid recovery) & use in daycare surgery
S/e: same with sevoflurane for respiratory s/e, however on CVS has effect of tachycardia with rapid response to concentration
MAC: 6.0
Describe: has pungent smell (irritate the airway and can cause laryngospasm, coughing and secretions)
IV induction is divided into
- barbiturate: sodium thiopentone (STP)
- non barbiturate: propofol, ketamine, midazolam, etomidate
Criteria for ideal IV anaes agents
- rapid, smooth and safe
- limited CVS and respiratory effects
- should possess analgesic activity
- rapid return of consciousness
MOA of induction agents
All except ketamine potentiate GABA receptor
Ketamine: NMDA receptor
Propofol
- indication
- onset
- s/e
- CI
Indication (SIMS)
- sedation
- induction (+ TIVA)
- maintenance
- sedation in status epilepticus
Onset: fast onset (40-50sec)
S/e:
CVS: hypotension, brady (cardiovascular depressant)
Respi: resp depression, temporary apnea
Reduce PONV
CI: allergy to eggs, hypotension, known hypersensitivity to propofol
Thiopentone
- indication
- onset
- s/e
- CI
Pale yellow powder
Indication
- induction (potent anaest)
- tx status epilepticus
- induce coma (NOT used as maintenance agent)
Onset: 30-40s (short onset)
S/e:
CVS: hypotension with tachycardia
Respi: respiratory depression and bronchospasm
Anticonvulsant, anti analgesic (poor)
CI
- severe asthma & COPD (bronchoconstriction)
- porphyria, allergy to barbiturates
Ketamine
- indication
- onset
- s/e
- CI
Indication
- hypnotic
- analgesic (mass casualties, burn dressing)
- induction in pt risk of hypotension and bronchial asthma
- mx for severe bronchospasm and hypotensive pt
Onset: 1 min
S/e:
CVS: increase BP and HR
GIT: PONV
LA properties: emergence delirium, vivid dreams, hallucinations, increase catecholamine secretions
CI
- increase ICP
- hypertension
- glaucoma
- heart failure