iv inducing agents.pptxxxxxxxxxxxxxxxxxx

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1. IV INDUCING AGENTS

2. Properties of an ideal anesthetic agents FOR PATIENTS : - Pleasant, non irritating - No pain on injection - No emetic effects -No emergence phenomenon ( eg -nightmares) - No excitatory phenomenon ( eg -hiccups) - Minimal cardiovascular and respiratory depression

3. For surgeons: - Rapid onset - Adequate muscle relaxantion - No interaction with neuromuscular blocking agents - Non-inflammable , no explosive For anesthetist: -No venous sequelae -No toxic to other organs -No histamine release -No hypersensitivity reactions -Water soluble formulations -No stimulation of porphyria

4. USES OF IV INDUCING AGENTS Induction of anesthesia For analgesia As a sole anesthesia For amnesia To blunt cardiovascular response to intubation For sedation

5. CLASSIFICATION Barbiturates - Thiopentone - Methohexitone Non- barbiturates - Ketamine - Propofol - Etomidate - Opoids - Benzodiazepines - Phenothiazines

6. SODIUM THIOPENTONE An ultra-short-acting barbiturate used commonly in the induction phase Available as yellow powder with bitter taste and faint smell of garlic Stored in nitrogen to prevent reaction with atmospheric co2 and mixed with 6% anhydrous sodium carbonate to increase its solubility in water Available in single dose vials 500mg and dissolved in distilled water to produce 2.5% (25mg/ml) Freshly prepared can be used for 24hrs

7. MOA- M ediates their action through GABA-A subtype increasing the membrane conductance to chloride ion H yperpolarisation of membrane Also inhibits synaptic transmission of excitatory neurotransmitters like acetylcholine, glutamate

8. Dose- I nduction- 4-6mg/kg IV Sedation- 0.5-1.5mg/kg Metabolised by liver, excreted by kidneys Onset of action: 15 secs Elemination t1/2 : 12 hrs but consciousness regained after 15-20mins due to redistribution

9. Systemic effects CNS- decrease ICP, CMR(Cerebral Metabolic Rate) CVS- depression of myocardial contractility - peripheral vasodilation - decrease BP Respiratory- transient apnea bronchospasm , laryngospasm respiratory depression at higher dose Skeletal muscle- reduced muscle tone at higher dose Eye- decreased IOP Liver, Kidney- decreases hepatic and renal blood flow

10. C omplications * General - Respiratory depression Cardiovascular depression laryngospasm , bronchospasm Hiccups, coughing Allergic manifestations like cutaneous rash, pruritus , anaphylaxis Postoperative disorientation, vertigo, euphoria

11. *Local Perivenous and intramuscular injection: tissue necrosis and ulceration Intra-arterial injection (dreadful complication which can lead to gangrene and limb loss) Thrombophlebitis Injury to the median nerve

12. Contraindications Porphyria Hepatic, renal disease Asthma, airway obstruction Shock, hypotension Heart block Myotonic dystrophy h/o of previous anaphylaxis

13. METHOHEXITONE SODIUM Short-acting and has a rapid onset of action 3 times more potent and similar in its effects to thiopentone sodium Has a quicker and brief action (5-8mins) Indicaion - oral surg and dentistry ADR- excitement during induction and recovery period

14. PROPOFOL 2,6-dispropylphenol Most commonly used IV anesthetic agent in modern day anesthesia Short acting for both induction as well as maintenance Available as milky white solution in 1%, 2% Prepared as oil based emulsion containing 10% soyabean oil, 2.25% glycerol and 1.2% purified egg lecithin Used within 6 hrs after opening the vial as egg is good media for bacterial growth Acts as hypnotic, aniemetic , antipruritic , bronchodilator, decreases ICP, IOP, but poor analgesic, poor muscle relaxant

15. MOA- Mediates action through GABA-A subtype receptor increasing the membrane conductance to chloride ion Hyperpolarisation of membrane Also inhibits glycine receptors

16. Dose- induction- 2mg/kg iv maintenance- 50-150micro gram/kg/min sedation- 25-75 microgram/kg/min Onset of action- 15secs Peak effects- 90-100secs Elemination T1/2- 2-4 hrs but awakening time :2-8mins due to redistribution

17. Systemic effects CVS- hypotension Respiratory system- respiratory depression CNS- decreases CMR and ICP Eye- reduces IOP GIT- anti-emetic (decreasing central serotonin release) Immunologic- Anti- pruritic

18. USES Bcoz of shorter half life , it is the agent of choice for induction Agent of choice for day care surgery (due to smooth recovery) Along with opoids ( ramifentanyl ), profol is the agent of choice for TIVA Propofol can be used to produce sedation in ICU Agent of choice for inducion in susceptible for malignant hyperthermia

19. Advantages Antiemetic Antipruritic Bronchodilator(safe in asthmatics) Safe in porphyria patients Safe in head injury Rapid, smooth recovery

20. Side effects Pain on injection site (preceding xylocaine or mixed with xylocaine solution can be given) CVS depression(hypotension, bradycardia ) Respiratory depression(apnea) Excitatory phenomenon, myoclonus , convulsions Allergic reactions(skin rashes, anaphylactic reaction) Sepsis Propofol infusion syndrome

21. KETAMINE Phencyclidine derivative, available as solution 10mg/ml and 50mg/ml with preservative benzathenium chloride Produce dissociative anesthesia i.e dissociates thalamus from the limbic cortex (dissociates individuals from surrounding and oneself- cataleptic state) Strong analgesic but poor muscle relaxant

22. MOA: Inhibits NMDA receptors on thalamo -neo-cortical projections Inhibits cortex- unconsciousness Inhibits thalamus- analgesia Stimulates limbic system- emergence reactions, hallucination

23. Onset of action- 30-60 secs after IV Duration of action : elemination T1/2 : 2-3 hrs but early consciousness after 15-20mins bcoz of redistribution Dose: Induction dose- 2mg/kg IV, 4-6mg/kg IM

24. Systemic Effects CNS- raised ICP, potent analgesia Emergence reactions : vivid dreaming, illusions, excitement , confusion, euphoria Hallucination CVS- Tachycardia, HTN Increased myocardial oxygen demand Respiratory- pharyngeal and laryngeal reflexes preserved stimulates respiration potent bronchodilator Skeletal muscle- tone increased Eye- increased IOP, pupils dilate GIT- salivation increased, increased intragastric pressure

25. Indications High risk patients (higher categories ASA) Used in patients in shock Pediatric anesthesia used in remote places, inexperienced manpower, developing countries as less cardiorespiratory depression Analgesia and sedation Preferred agent in patients with full stomach Sole agent in minor procedures (I and D,dressing , burn)

26. Advantages Good analgesic property Smooth induction Do not blunt protective airway reflexes Can be given IM also Can be used in patient with hemodynamic instability ( shoch , hypotension) Can be used in asthamatics (acts as bronchodilators) Pediatric anesthesia Can be used in difficult locations, developing countries

27. Adverse effects Emergence reactions, nightmares, hallucinations Hypertension, tachycardia Prolonged recovery Increased salivation Increased muscle tone Increased ICP, IOP Allergic reactions: skin rashes

28. Contraindications Ischemic heart diseases, aneurysms,HTN Airway obstruction Raised ICP (head injury, intracranial lesions) Raised IOP(ocular injury cases) Psychiatric disorders Pheochromocytoma Hyperthyroidism

29. ETOMIDATE Carboxylated imidazole , also acts through GABA Short acting induction anesthesia Has a briefer duration of action (4-8mins) than thiopentone Etomidate is highly protein bound and metabolised by hepatic and plasma esterases to inactive products Onset of action- 30-60 secs Peak effect- 1 min Indications - as sedative, for short procedures such as reduction of dislocated joints and cardioversions , aneurysm surgery

30. Advantages Most cardiovascular stable among all IV agents Minimal respiratory depression No histamine release It decreses ICT

31. Side effects Adrenocortical supression on longterm infusion Nausea, vomiting High incidence of myoclonus Injection is painful High incidence of thrombophlebitis Can cause Vit C deficiency Cause inhibition of platelet function No analgesia

32. BENZODIAZEPINES Used in anesthesia for: - Premedication (to reduce anxiety) - Amnesia - As a sole agent to non-painful procedures like bronchoscopy , gastroscopy under local analgesia - As induction agent(rarely) - To prevent hallucination by ketamine - to control convulsions

33. Drugs : Short acting- midazolam (1-2.5 mg iv) Intermediate acting- diazepam (dose: 0-2-0.5mg/kg IV) Long acting- lorazepam (0.04mg/kg) All benzodiazepines produce : anxiolytic , anterograde amnesia, sedative, hypnotic, anticonvulsant and spinally mediated muscle relaxant properties

34. MOA: Mediates action through GABA-A subtype receptor increasing the membrane conductance to chloride ion Hyperpolarisation of membrane Metabolised in liver, excreted by kidney Antidote is flumazenil

35. Systemic effects CNS- reduces CMR , brain o2 consumption and ICP Respiratory – at higher dose causes respiratory depression CVS- minimal reduction in BP, HR and CO

36. OPOIDS Classification Natural opiates- - Morphine , Codeine, Thebaine 2) Semisynthetic opiates- - Heroin, Dihydromorphine , Oxymorphine 3) Synthetic opiates- - Pethidine , fentanyl , Remifentanyl , Tramadol

37. MOA - Supraspinal level (medulla)- block nociceptive transmission binding with receptors in rostroventral region of medulla Spinal level- act on substantia geltinosa of dorsal horn and decrease excitatory transmitters Cellular level- binds with receptors that stimulate G protein synthesis and increase cAMP pathway

38. Uses- Potent analgesic agent Premedication As Inducing agent To Blunt cardiovascular response in intubation In daycare surgery with remifentanyl and propofol To treat pulmonary oedema (morphine) In painless labour during epidural analgesia As sedatives in ICU To abolish postoperative shivering ( pethidine and tramadol )

39. Systemic effects CVS- hypotension, bradycardia Respiratory- respiratory depression CNS- analgesia, sedation Muscular system- causes muscle rigidity Endocrine system- decreses ACTH, LH, FSH and increases GH,prolactin , ADH GIT- inhibits gut motility and decreases gastric emptying causing constipation Eye- causes decrease in IOP and miosis Renal – causes urinary retention