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  1. TOPIC: IV ANAESTHESIA DRUGS INTERNAL EXAMINER: LT.COL.Dr.Ashok Professor PSIMS,Gannavaram POSTGRADUATES: Dr.Vara lakshmi Dr.Shashank Dr.Jane Ramya
  2. INTRAVENOUS ANAESTHETICS Post Graduates and The Faculty of Dr. PSIMS & RF
  3. Thiopentone Sodium 1) What are the commonly used IV induction agents? a) Thiopentone sodium b) Propofol c) Ketamine d) Etomidate.
  4. 2) Thiopentone sodium belongs to which group pharmacologically? A) Thiopentone sodium is ultra-short acting barbiturate which can be administered only in an IV route.
  5. 3) What is the pH of Thiopentone and where is it significant in anaesthesia ? A) Thiopentone sodium is highly alkaline with a pH of 10.6. Hence it should not be given just prior to the administration of drugs with different pH, like Scoline. • There should be adequate saline flush between the two drugs.
  6. 4) How is Thiopentone sodium available and how do you prepare it for induction? A) Thiopentone sodium is available as crystalline powder in a vial with a strength of 500 mg or 1 gm. I will dilute with normal saline to make it 25 mg per ml solution for slow IV administration.
  7. 5) What is the dose of Thiopentone sodium for induction of anaesthesia ? A) In a healthy adult the dose is 3-5 mg/Kg body weight for normal induction. • Sleep dose of Thiopentone sodium is 100mg/min (4ml/min of a 2.5% solution). Till the patient goes to sleep.
  8. 6) What are the contraindications of Thiopentone sodium ? A) Bronchial asthma , Acute bronchitis , and atopic individuals are relative contraindications in addition to severe hypotension. Acute Intermittent Porphyria and known allergy to sulpha drugs are the absolute contraindications.
  9. 7) What severe damage can occur by wrong administration of Thiopentone sodium ? A) Accidental intra-arterial administration of thiopentone results in the following : 1.Severe pain in the area supplied by the artery. 2. Spasm of artery leading to decreased blood supply. 3.Burning sensation of the area involved. 4. Spasm of the muscles involved. 5. Cyanosis and gangrene of the distal areas. 6. Systemic hypotension leading to shock.
  10. 8) What is the management of such incident? a- Do not remove the culprit needle from the artery. b- Inject preservative free 1% Lignocaine 5ml (50 mg) + phenoxybenzamine (a blocker) 0.5 mg bolus or 50- 200mcg/min infusion into the artery. c- Infuse plenty of normal saline into the site. d- Keep the arm elevated. e- Inj. Papavarine 40-80 mg to be given into the artery. F – Stellate Ganglion block if required.
  11. 9) What are the non-induction uses of Thiopentone sodium clinically ? A) • It is a powerful agent to reduce the raised ICP. • It is administered to manage Status Epilepticus. • It is administered as Truth Serum in criminal cases. • It is used as one of the drugs in TIVA for short surgical procedures.
  12. 10) What was the historical connection between Thiopentone sodium and Pearl Harbor attack? A) After the Pearl Harbor attack the casualties were induced with standard doses of Thiopentone sodium which resulted in multiple intra-op deaths due to severe hypotension. The drug went into disrepute for almost a decade. Later the reason for death was identified as pre-operative hypotension and the drug was brought back to clinical usage.
  13. 11) What are the special precautions while administering Thiopentone sodium ? A) Thiopentone sodium should be administered very slowly in extremes of age and the dose to be minimized in elderly patients.
  14. 12) What is the effect of Thiopentone sodium on the fetus when administered to the pregnant mother ? A) The effect is minimal because of the multiple dilutions of the drug before it reaches fetal circulation.
  15. Propofol 1) What is the pharmacological composition of Propofol ? A) Propofol is a milky white emulsion with following composition. • Propofol • Egg lecithin (purified) • Soya bean oil • Isopropyl phenol • Glycerol.
  16. 2) What are the unique pharmacological features of Propofol ? A) Propofol can be administered only through IV route. • It produces peripheral vasodilation leading to systemic hypotension. • Onset of action is fast and recovery time is also short making it a very useful drug in day care anaesthesia.
  17. 3) What are the advantages of Propofol ? A) • Safe induction agent in known hypertensive patients. • Very useful drug in day care anaesthesia due to its fast in & fast out property. • Useful in ICU sedation for short periods. • Useful in irritable airway diseases.
  18. 4) What are the precautions to be taken in Propofol administration ? A) • To be administered with care in hypotensive patients. • To be administered carefully in atopic individuals and in patients with egg allergy. • IV injection is painful, hence prior injection of lignocaine is advised.
  19. 5) What is Propofol infusion syndrome ? A) It is a syndrome seen usually in ICUs , when the Propofol is used as an infusion for sedation for prolonged periods at 4mg/kg/hr, usually more than 48hrs. The signs and symptoms are the result of muscle injury and release of intracellular toxic content Acute refractory bradycardia leading to asystole in the presence of one or more of the following Metabolic acidosis ( base defecit > 10mmol/litre) Rhabdomylosis Hypotension Hyperlipidemia Tachypnea Enlarged or fatty liver Shock Cardiomyopathy with acute cardiac failure Skeletal myopathy Hyperkalemia Lipemia
  20. 6) How do you manage this syndrome ? A) • Stop Propofol infusion immediately. • Rapid fluid resuscitation with normal saline. • Inj. Furosemide to flush out the excessive drug. • Inj. Hydrocortisone IV NOT to be given. • Inotropic support if required. • Hemodialysis if indicated.
  21. 7) What do you know about Propofol induced sepsis ? A) Propofol may be a potential source of systemic sepsis as it is a favorable medium for bacterial growth. This is commonly seen in opened and reused Propofol vials.
  22. 8) How do you prevent this sepsis ? A) EDTA added Propofol preparations are available in the market which will prevent the growth of bacteria in the vials. Not using the partially used vials next day is a safe practice to prevent Propofol induced sepsis.
  23. KETAMINE 1) What is the pharmacological precursor for Ketamine? Say a few words about its history? A) • Ketamine is phencyclidine derivative and the latter drug was used initially as a recreational drug. • Ketamine was introduced into clinical practice in 1970 by Corssen and Domino.
  24. 2) What are the unique pharmacological actions of Ketamine? A) • Ketamine is a powerful analgesic agent. • It produces rapid dissociative anaesthesia. • It increases the heart rate and blood pressure. • It increases IOP , ICP and IGP. • It reduces the seizure threshold, sometimes precipitating imminent Seizures. • It produces hallucinations- visual, auditory and tactile- both positive and negative also. • Ketamine partially suppresses the pharyngeal and laryngeal reflexes. • Ketamine is a bronchodilator and so useful drug in bronchial spasm or asthma. • Ketamine increases the oral secretions , which may sometimes lead to laryngospasm. • Ketamine increases the skeletal muscle tone.
  25. 3) What is the role of Ketamine in day-care anaesthesia? A) Very useful drug in TIVA because of its unique analgesic and CVS stabilizing properties . Quick elimination - half time is also a favorable character.
  26. ETOMIDATE 1) What are the physical and pharmacological properties of Etomidate? A) Etomidate is usually supplied in vials as a milky white solution or transparent liquid. It is a powerful induction agent.
  27. 2) What is the dose of Etomidate for induction? A) 0.2 to 0.6 mg/kg, IV is the standard induction dose of Etomidate.
  28. 3) What are the advantages of Inj. Etomidate? A) Etomidate is a drug with cardiac stability. So, can be safely administered in cardiac patients without any unwanted changes in blood pressure or pulse rate.
  29. 4) What are the limitations of Etomidate usage? A) a) Etomidate is known to disturb the hypothalamus pituitary adrenal axis. b) It causes involuntary muscle movements and also reduces the threshold of seizures in patients.
  30. 5. What are the relative contraindications for the usage of Etomidate in anaesthesia? A) Hypopituitarism, Addison’s disease and known cases of epilepsy are the relative contraindications of Etomidate.
  31. ANTI-CHOLINERGICS 1. What are the commonly used anticholinergics in anaesthetic practice? A) Inj Atropine or Inj Glycopyrrolate are the two commonly used anticholinergic drugs in Anaesthesia.
  32. 2. What are the indications of usage of anticholinergics? A) They are used to: • Reduce the salivary and bronchial secretions. • To reduce the vagal tone and thus preventing the unwanted bradycardia during anaesthesia. • They are mild bronchodilators and hence are useful in irritable respiratory system disorders.
  33. 3. What are the disadvantages of Anticholinergics? A) • They produce unwanted tachycardia and hence they must be used with caution in Tachyarrythmias, Phaeochromocytoma or hyperthyroidism. • They block the sweat glands, so must be avoided in patients running high temperatures. • They create dry mouth and dry respiratory tract which may cause great discomfort to patients. • Atropine being tertiary amino compound crosses the blood brain barrier and may cause cerebral anticholinergic syndrome especially in elders.
  34. 4. What are the dosages and preparation of anticholinergics? A) • Atropine is available as 1ml ampoule containing 0.6 or 0.5 mg of Atropine sulphate. • 1mg/ml preparation is also available for ICU usage for treatment of OP poisoning • Dose is 0.6 – 2 mg IM/IV, not more than 10 µg/kg in children. • Glycopyrrolate is available as 1ml ampoule containing 0.2 mg. • Dose - 0.005 – 0.008 mg/kg body weight IV or 0.1 – 0.3 mg IM or 1 – 2 mg oral.
  35. BENZODIAZEPINES 1. What are the commonly used Benzodiazepines in the anaesthesiology and for what purpose? A) Midazolam, Diazepam and Clonazepam are the frequently used benzodiazepines in anaesthesia. Midazolam is used as an anxiolytic agent before induction. Diazepam is used as an anticonvulsant during an attack of epilepsy or eclampsia. Alprazolam is used as a mild sedative on the night before surgery for a peaceful sleep.
  36. 2. What are the pharmacological differences between Diazepam and Midazolam? A) Onset of action is faster, duration of action is shorter and the elimination half life is shorter with midazolam compared to diazepam. Midazolam is water soluble and hence less painful when administered intravenously, where as Diazepam is a thick viscous liquid that causes pain in IV injection. Diazepam is more potent anticonvulsant than midazolam and hence it is a preferred drug in an attack of epilepsy, but its duration of action may extend upto ~ 72 hrs.
  37. 3. What are the limitations of Midazolam? A) Benzodiazepines are not analgesic drugs and if administered in the presence of acute pain, will cause delirium in the patient with severe pain as they act as antanalgesics.
  38. FENTANYL 1. Why is Inj Fentanyl is a preferred Opioid chosen for intra-op analgesia? A) Fentanyl is a powerful synthetic opioid drug which produces prompt and profound analgesia,is 100 times more potent than Inj Morphine. B) Onset of action is within 5 min and effect lasts for 4-6 hrs. Release of Histamine is minimal and hence appearance of rash, hypotension or bronchospasm are rare events with fentanyl.
  39. 2. What is the dose of Fentanyl? Which are the chief side effects of Fentanyl? A) Analgesic dose of Fentanyl is 1-2 µg/kg body weight given in IV route. Onset of action is after five minutes and peak action is at 45 min after administration. The chief side effect after Fentanyl is the chest wall rigidity, hypotension and over-sedation. The side effects can be minimized by slow administration of Fentanyl.
  40. 3. What are the non anaesthetic uses of Fentanyl? A) Fentanyl can also be used for: • Post op analgesia. • Post traumatic analgesia in emergency room. • To manage acute MI. • ICU sedation and analgesia
  41. DEXMEDETOMIDINE 1.Dexmedetomidine belongs to which group pharmacologically? A) Dexmedetomidine belongs to α2-adrenergic agonist group and it is different from Clonidine in the following way: α2 stimulant 1600 times more selective (α2/α1=1600:1) compared to Clonidine (α2/α1=220:1).
  42. 2.What are the pharmacological actions of Dexmedetomidine? • It is mild sedative. • It is an anti-hypertensive drug. • It is a mild analgesic. • It is a tranquilizer during analgesic. • It reduces the pressor response of the laryngoscopy and intubation in general anaesthesia. • It maintains the heart rate.
  43. 3. What are the advantages of Dexmedetomidine in clinical use ? A) 1. Rapid onset of action. 2. Rapid recovery from the action. 3.Arousable sedation. 4. Mild analgesia present. 5. Maintains cardiovascular stability. 6. Can be administered by IV infusion.
  44. 4. What are the precautions to be taken during administration of Dexmedetomidine? A) • Dexmedetomidine administration is contraindicated in patients with severe hypotension and bradycardia. • Sporadically few patients will develop unexpected hypertension and tachycardia immediately after starting the Dexmedetomidine infusion. The reason for this is the disturbance in Nor-epinephrine re-uptake mechanism. In such patients Dexmedetomidine to be terminated immediately and IV Esmolol or IV Labetalol to be given to correct the situation • Unwanted hypotension and severe bradycardia may be seen in certain sensitive patients. Reduction of infusion rate is indicated in such patients.
  45. 5. What is the role of Dexmedetomidine in ICU care? A) Dexmedetomidine can be administered as an infusion for sedation in ICU with minimum side-effects. The context sensitivity half-life of the drug is short and hence it is a safer alternative.