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inducing agent

INTRA VENOUS INDUCING AGENTSDR N K AGRAWALJNMC,SAWANGI What are the properties of an ideal IV agent?Should act in one arm brain circulation timeShould not cause pain on inductionShould not be irritantShould have short half lifeMetabolites should be non activeNot hepatotoxic

THE TOPIC WILL BE DISCUSSEDShould not depend on renal for excretionNo respiratory depressionShould cause hallucinationNo dissociationShould have hemodynamic stabilityShould not change cerebral blood flowLeast PONVNo allergic reactionUseful for TIVADerivative of phenol

Have hypnotic properties

2-6 disopropofolAlkyphenol 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 vanPROPOFOL1 % excreted in urine,2% fecesMetabolized hepatic,kidney,lungs

Elimination Half life is 2-8 minDistribution half life is 4min to 23 hrs

Dose is 1-2 mg/kgInfusion is 200ug/kg/min

metabolismAct on GABADirectly act on neurons of spinal cardAt dose of 2.5 mg/kg induces hypnosis in 90-100 secIt causes sedation,hypnosis,amnesiaHypnosis lost for 6-10 minHallicination,sexual fantasis,opisthotonus have been reportedHigh doses are needed for less than 2 yr,with age dose requirement is reducedCNSDecreases arterial BPDiastolic BPStroke volumePeripheral resistancePawpPulmonary vascular resistanceHR may or may notMyocardial blood flow reduced as well demandCVSDecreases ICTToleranceReduces CPPCp50Apnea depends on dose, speed of injection,concommitent premedicationRespiratory

Uses and Doses of Intravenous PropofolInduction of general anaesthesia 1-2.5mg/kg IV dose reduced with increasing age Maintenance of general anaesthesia 50-150g/kg/min IV combined with N2O or an opiate Sedation 25-75g/kg/min IV Antiemetic 10-20mg IV, can repeat every 5-10min or start infusion of 10g/kg/min N2O, nitrous oxide.

Pain on injectionHypotensionMyoclonusApnea

thromboplhebitiesSide effectsHighly alkalinePrepared with water or normal salineStable for one weekNot compatible with pan.,vec,atra,sufen,alfenNa thiopentoneExcreted through liverMetabolites are inactive, water soluble ,excreted in urineBio transformation in four stage oxidation desulfuration dealkylation destructionDose is 4-5 mg/kgHalf life is 7-17 hrsits 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 timeUltra short actingCrosses blood brain barrierBound to albumin

Mechanism of actionDose dependant CNS DepressionDecreases cerebral metabolic rateProtect brain from ischemiaReduces CMRO2

CNSOn injection garlic or onion test in 40%Allergic reactionIrritationnecrosisSide effectsInfuse normal salineHeparinNerve blockIntra arterial injectionIncreases HRPeripheral vascular resistance decreasedNegative inotropic effectFall in cardiac out putDecreases ventricular fillingDecreases sympathetic outflow CNSCVSDepressionApnea

Respiratory systemWood 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.

contraindicationIt is imidazole derivativeMolecular wt 342.69Water insolublePh 6.9Dose not precipitateETOMIDATEgeneral anaesthesia 0.2-0.6mg/kg IV Maintenance of general anaesthesia 10g/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 armbrain circulation after a normal induction dose (0.3mg/kg).Etomidate has no analgesic activity. Plasma levels required for the maintenance of anaesthesia are approximately 300 to 500ng/mL, for sedation are 150 to 300ng/mL, and for awakening are 150 to 250ng/mL mechanism by which etomidate produces hypnosis is fully knownReduces CMR and CBFNo change in MAPCPP maintain or increased

Dose not affect ventilationNo histamine releaseNo effect on co2 responseNo effect on Pao2PACO2 slightly increasedNO CHANGE INHR,MAP,STROKE VOLUME,CARDIAC INDEX,PAWP,CVP,CVSIt provide sedation hypnosis, anxiolysisAnalgesia sympatholysisDOSE- 0.25 to 1 mg/kgDEXMETODINE-ALPHA ADRENERGIC AGONISTMetabolize in liver2%Metabolite are active85% by kidney14% via liverRapidly distributed and extensively metabolized in liverExcreted through urine and fecesSensitive half life 4-6 minHalf life 2-4 hoursSEDATIVE- the patients are awake and responsiveANALGESIA-good analgesic, when given in epidural space action within 2-20 minAbsorbed in CSF Little effect on ICP CBF

C N SVentilatory response increasedResponse to co2 increasedRR increasedPaco2 increased by 20%RSDecrease in HR-Sympathetic vascular resistanceHence decreases cardiac out put cardiac out putCVS