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What are the properties of an ideal IV agent?
Should act in one arm brain circulation time
Should not cause pain on induction
Should not be irritant
Should have short half life
Metabolites should be non active
Not hepatotoxic
Should not depend on renal for excretion
No respiratory depression
Should cause hallucination
No dissociation
Should have hemodynamic stability
Should not change cerebral blood flow
Least PONV
No allergic reaction
Useful for TIVA
Derivative of phenol
Have hypnotic properties
2-6 disopropofol
Alkyphenol are oil, highly lipid soluble
Ctenophore is 1% propofol,10% soybean oil,2.25 glycerol, and 1.2% purified egg
Fospropofol is USA FDA Aqua van
1 % excreted in urine,2% feces
Metabolized hepatic,kidney,lungs
Elimination Half life is 2-8 min
Distribution half life is 4min to 23 hrs
Dose is 1-2 mg/kg
Infusion is 200ug/kg/min
Act on GABA
Directly act on neurons of spinal card
At dose of 2.5 mg/kg induces hypnosis in 90-100 sec
It causes sedation,hypnosis,amnesia
Hypnosis lost for 6-10 min
Hallicination,sexual fantasis,opisthotonus have been reported
High doses are needed for less than 2 yr,with age dose requirement is reduced
Decreases arterial BP
Diastolic BP
Stroke volume
Peripheral resistance
Pawp
Pulmonary vascular resistance
HR may or may not
Myocardial blood flow reduced as well demand
Uses and Doses of Intravenous Propofol Induction of general anaesthesia 1-
2.5 mg/kg IV dose reduced with increasing age
Maintenance of general anaesthesia 50-150 µg/kg/min IV combined with N2O or an opiate
Sedation 25-75 µg/kg/min IV Antiemetic 10-20 mg IV, can repeat every 5-10 min or start infusion of 10 µg/kg/min N2O, nitrous oxide.
Highly alkaline
Prepared with water or normal saline
Stable for one week
Not compatible with pan.,vec,atra,sufen,alfen
Dose is 4-5 mg/kg
Half life is 7-17 hrs
its affinity for fat, relatively large volume of distribution, and low rate of hepatic clearance, thiopental can accumulate in tissues, especially if given in large doses over a prolonged period. The plasma drug level increases when repeat doses of drug are given.
Act in one arm brain circulation time
Ultra short acting
Crosses blood brain barrier
Bound to albumin
Dose dependant CNS Depression
Decreases cerebral metabolic rate
Protect brain from ischemia
Reduces CMRO2
Increases HR
Peripheral vascular resistance decreased
Negative inotropic effect
Fall in cardiac out put
Decreases ventricular filling
Decreases sympathetic outflow CNS
Wood has listed the contraindications to IV barbiturate use.[227]
(1) When there is respiratory obstruction or an inadequate airway, thiopental may worsen respiratory depression.
(2) Severe cardiovascular instability or shock may preclude its use.
(3) Status asthmatics is a condition in which airway control and ventilation may be worsened further by thiopental.
(4) Porphyries may be precipitated or acute attacks may be accentuated by the administration of thiopental.
(5) Without proper equipment (IV instrumentation) and airway equipment (means of artificial ventilation), thiopental should not be administered.
general anaesthesia 0.2-0.6 mg/kg IV
Maintenance of general anaesthesia 10 µg/kg/min IV with N2O and an opiate
Sedation and analgesia Limited to periods of brief sedation because of inhibition of corticosteroid synthesis N2O, nitrous oxide.
The primary action of etomidate on the CNS is hypnosis,
which is achieved in one arm–brain circulation after a normal induction dose (0.3 mg/kg).
Etomidate has no analgesic activity. Plasma levels required for the maintenance of anaesthesia are approximately 300 to 500 ng/mL, for sedation are 150 to 300 ng/mL, and for awakening are 150 to 250 ng/mL
mechanism by which etomidate produces hypnosis is fully known
Dose not affect ventilation
No histamine release
No effect on co2 response
No effect on Pao2
PACO2 slightly increased
Rapidly distributed and extensively metabolized in liver
Excreted through urine and feces
Sensitive half life 4-6 min
Half life 2-4 hours
SEDATIVE- the patients are awake and responsive
ANALGESIA-good analgesic, when given in epidural space action within 2-20 min
Absorbed in CSF Little effect on ICP CBF