Anaesthetic agents (sedatives and opioids Flashcards by Muambo Eko

name 5 induction agents

Propofol
 Benzodiazepines
 Barbiturates
 Etomidate
 Ketamine

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name 5 opioids

 Morphine
 Fentanyl
 Codeine
 Tramadol
 Remifentanil

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what are the main uses of propofol

Anaesthetic induction, maintenance

of anaesthesia, sedation, anti-emesis.

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what effects does propofol have on respiratory system

decreases tidal volume increases respiratory rate, apnoea greater than 30 secs, possible bronchodilation

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what effects does propofol have on cardiovascular system

decreases cardiac output and systemic vascular resistance and bP. inhibits baroreceptor reflex, decreases myocardial blood flow, decreases oxygen consumption. can supress atrial tachycardia and it is cardio protective with anaesthetic gases

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what are the pros of using propofol

 Not an MH trigger
 No adrenal suppression
 Pleasant dreams
 Relieves pruritis from opiates
 Anti-emetic even at low doses
(10mcg/kg/min)

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what does anti emetic mean

prevents vomiting and nausea

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what are the cons of propofol

Anaphylactoid reactions.
 Pancreatitis (Hyper TG)
 Pain on injection (rare); thrombophlebitis
 Propofol infusion syndrome
 Acute bradycardia leading to asystole with
metabolic acidosis, rhabdo, hyperlipidemia,
fatty liver, hyperkalemia

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what are the uses of barbiturates

Thiopental: Induction, cerebral protection (e.g. status epilepticus)
 Methohexital: Induction, especially for ECT
 Phenobarbital: Seizure suppression
 Anxiolysis

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how does barbituates affect respiratory system

tidal volume decreases, respiratory rate decrease and apnoea

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how does barbituates affect cardiovascular system

Peripheral vasodilation
Negative inotropy
Increased HR
Can prolong QT interval

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how does barbituates affect neurological system

Loss of consciousness
decreases CMRO2, decrease ICP, decreases CBF.
Seizure suppression
Prolonged effects
(Bioaccumulation)

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how does propofol affect neurological system

Loss of consciousness
Seizure suppression
Decrease ICP
Decrease IOP / CPP
Autoregulation intact
Antiemesis

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what are cons of barbituates

Garlic or onion tastes
 Allergic reactions
 Local tissue irritation or rarely necrosis
 Induction of P450 system
 Bronchoconstriction in asthmatics

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name a short acting intermediate acting and long acting benzodiazepines

Midazolam (short acting)
 Lorazepam and Temazepam (intermediate)
 Diazepam (long acting)

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what receptor does benzodiazepines act on and what are the desired effects

Bind to GABA-A receptor, enhance response
to GABA
 Leading to hypnotic, sedative, anxiolytic,
amnestic, anticonvulsant, muscle-relaxation
properties
 Increases seizure threshold

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what effects does benzodiazepines have on the respiratory system

decreases musclar tone in upper airway, decreased response to increased co2, decrease hypoxic response

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what effects does benzodiazepines have on the cardiovascular system

decrease in systemic vascular resistance. maintains cardiac output and barorecptor reflexes

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what effects does benzodiazepines have on the neuro system

Anxiolysis
Sedation
Amnesia
Anticonvulsant

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what does anxiolysis mean

What are Anxiolytics, sedatives, and hypnotics? Anxiolytics, sedatives and hypnotics are medicines that work on the central nervous system to relieve anxiety, aid sleep, or have a calming effect.

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name some adverse effects of benzodiazepines

Lorazepam and Diazepam can cause venous irritation and thrombophlebitis
 All can have extended effects
 Post-operative delirium
 Give appearance of sleep without restorative sleep

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why do you have to be careful using flumazenil with patients on chronic benzos

can cause seizures

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what receptor does ketamine act on

Phencyclidine-binds to NMDA Receptor

antagonist

which isomer is more potent in for ketamine s or r

what is dissociative anesthesia

Produces “dissociative anesthesia” because patients may not appear asleep (eyes open, reflexes intact.caused by ketamine

what are the main uses of ketamine

Anaesthetic induction  Sedation (maintains RR, common in paeds)  Analgesia (opioid sparing / acute procedures)  Bronchodilatation

what does ketamine do to respiratory system

increase salivation and relaxes bronchial smooth muscle, less mechanicial ventilation

what does ketamine do to cardiovascular system

increase bp hr co and myocardial oxygen consumption. | increases sns and can cause pulmonary hypertension

what does ketamine do to neuro system

``` increases cmr02 cbf icp Emergence reactions Vivid dreams, Extracorporeal experiences Hallucinations Nystagmus Increased muscle tone ```

what is special about etomidate interaction with gaba a receptor

GABA-A facilitation (lower dose of GABA required to activate receptor)  At higher doses can activate receptor independently

what does etomidate do to respiratory system

hyperventilation followed by briefr apnea, decrease hypercapnic response

what does etomidate do to cardiovascular system

haemodynamically stable, can cause increase bp and pr

what does etomidate do to neuro system

No analgesic effect Can prolong seizures in ECT lowers cbf cmro2 and icp by 50%

what are the endocrine effects of etomidate

Dose dependent inhibition of 11B-hydroxylase.  Occurs at lower doses than hypnosis by more than 20x so suppression lasts much longer, up to 72h  Can be used to treat hypercortisolaemia

what is dexmedetomidine

Alpha-2 receptor agonist (brain /spine)  Used for sedation, anxiolysis, withdrawal, delirium, opioid sparing analgesia. causes bradycardia, reduces co and initial increase in Bp

ascending pain pathway does what with stimulus

transmits it to cortex where it is perceived. fast and slow efferent

descending pain pathway does what to with stimulus

inhibits transmission. substantia gelantinosa

name four opioid receptors

MOP mu KOP kappa DOP delta NOP noiceptors

how do opioids work generally

bind to opioid receptors as agonists causing decreased release of pain transmission

how long does it take morphine to kick in and why

slow acting due to low lipid solubility, slow BBB penetration to act on the brain

describe morphine potency for recpetors

highly potent opioid especially for MOP > dop kop

what is morphine used for

analgesia, palliation, peri operative

what does morphine do to respiratory

supresses respiration and less response to co2

what does morphine do to cardiovascular system

vagal centre stimulation causing bradycardia, vasomotor suppression(area of the brain for breathing and bp)

what does morphine do to neuro system

sedation, analgesia, euphoria, supresses coughs, can cause vomiting

what is receptors does fentanyl target

mu and delta receptors

at what rate does fentanmyl act and why

fast acting high lipid soloubility enters brain rapid;y short duration of action though.

fentanyl or morphine which is more potent

fentanyl

how strong is codeine compared to fentanyl and morphine

not nearly as strong 50 % potency of morphine

what receptors does codeine target

weakly targets mu and kappa

what enzyme metabolises codeine(oral drug) and what do you have to consider

cyp2d6, cautious with ultra metabolisers and lack of efficacy in poor metabolisers, drug interactions

comment on tramadol potency , acion, side effects and effects on cardio

safer cardio profile, 1/10 potency compared to morphine acts on mu receptors and downards inhibiition pathways

what is remifentanil

potent mu agonist, short acting

what are remifentanil uses

Sedation in ICU  PCA in obstetrics  Pain relief during surgery  Total IntraVenous Anaesthesia ( TIVA)

what is tiva

The provision anaesthesia solely exclusively via the intravenous route. (Propofol + Remifentanil infusions).

what are pros of tiva

Avoids conventional anaesthetic gases  Improved cardiovascular profile  Less nausea and vomiting  Improved tube tolerance

what are cons of tiva

Need dedicated IV line  Based on algorithms ( Compartment model assumptions)  Risk of awareness