Nursing Pharmacology - Anaesthetics - drdhriti

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Nursing Pharmacology - Anaesthetics - drdhriti

  1. 1. Nursing Pharmacology - ANAESTHETICS Department of Pharmacology NEIGRIHMS, Shillong
  2. 2. What is Anaesthesia ??? • Anesthesia – is a reversible condition of comfort, quiescence and physiological stability in a patient before, during and after performance of a procedure. • General anesthesia – for surgical procedure to render the patient unaware / unresponsive to the painful stimuli – Drugs producing G. Anaesthesia – are called General Anaesthetics • Local anesthesia - reversible inhibition impulse generation and propagation in nerves. In sensory nerves, such an effect is desired when painful procedures must be performed, e.g., surgical or dental operations – Drugs producing Local Anaesthesia – are called Local Anaesthetics e.g. Procaine, Lidocaine and Bupivacaine etc.
  3. 3. General anaesthetics (Defn.) • General Anaesthetics are the drugs which produce reversible loss of all sensation and consciousness, or simply, a drug that brings about a reversible loss of consciousness • Remember !!! These drugs are generally administered by an anesthesiologist in order to induce or maintain general anesthesia to facilitate surgery • General anaesthetics are – mainly inhalation or intravenous • Local anaesthetics are drugs which upon topical application or local injection cause reversible loss of sensory perception, especially of pain in a localized area of the body
  4. 4. What are the Drugs used as GA ?What are the Drugs used as GA ? (Classification)(Classification) • Inhalation: 1. Gas: Nitrous Oxide 2. Volatile liquids: • Ether • Halothane • Enflurane • Isoflurane • Desflurane • Sevoflurane • Intravenous: 1. Inducing agents: • Thiopentone, Methohexitone sodium, propofol and etomidate 1. Benzodiazepines (slower acting): • Diazepam, Lorazepam, Midazolam 1. Dissociative anaesthesia: • Ketamine 1. Neurolept analgesia: • Fentanyl
  5. 5. Local Anaesthetics ESTER LINKAGE AMIDE LINKAGE (2 EYES!!) PROCAINE procaine (Novocaine) tetracaine (Pontocaine) benzocaine cocaine LIDOCAINE lidocaine (Xylocaine) mepivacaine (Carbocaine) bupivacaine (Marcaine) etidocaine (Duranest) ropivacaine (Naropin)
  6. 6. History - The Primitive techniquesHistory - The Primitive techniques • Club • Strangulation • Alcohol • Mesmerism • Plants
  7. 7. History – contd.History – contd. • General anesthesia was absent until the mid-1800’s • Original discoverer of general anesthetics – Crawford Long, Physician from Georgia: 1842, ether anesthesia • Chloroform introduced – James Simpson: 1847 • Nitrous oxide – Horace Wells in 1845 19th Century physician administering Chloroform
  8. 8. History – contd. • William T. G. Morton, a Boston Dentist and medical student - October 16, 1846 - Gaseous ether – Public demonstration gained world-wide attention – Public demonstration consisted of an operating room, “the ether dome,” where Gilbert Abbot underwent surgery for removal of a neck tumour in an unconscious state at the Massachusetts General Hospital • But, no longer used in modern practice, yet considered to be the first “ideal” anesthetic
  9. 9. They did it for a better tomorrow!They did it for a better tomorrow!
  10. 10. General Anaesthetics
  11. 11. Essential components of GA: • Cardinal Features:Cardinal Features: – Loss of all sensations – Sleep and Amnesia – Immobility or Muscle relaxation – Abolition of reflexes – somatic and autoonomic • Clinically – What an Anaesthetist wants ???Clinically – What an Anaesthetist wants ??? – TriadTriad of GAof GA • need for unconsciousnessneed for unconsciousness • need for analgesianeed for analgesia • need for muscle relaxationneed for muscle relaxation
  12. 12. 4 (Four) Stages and signs !!! • Traditional Description of signs and stages of GA • Typically seen in case of Ether • Slow action as very much lipid soluble • Also called Guedel`s sign • Signs are: 1.Stage I: Stage of Analgesia 2.Stage II: Stage of Delirium and Excitement 3.Stage III: Stage of Surgical anaesthesia 4.Stage IV: Medullary / respiratory paralysis
  13. 13. signs & stages of GA – contd.signs & stages of GA – contd.
  14. 14. But not seen these days, because! • Availability of rapidly acting agents – IV as well as Inhalation • Mechanical control of Respiration • Pre-operative and post operative Drugs – Atropine – dilate pupil, Opioid – depressing of respiration and SMRs • Important signs observed by anaesthetists: – If no response to Painful stimulus - stage III – On Incision - rise in BP, respiration etc. – light anaesthesia – Fall in BP, respiratory depression – deep anaesthesia • Modern methods: Monitoring of Vital signs by CAM (computer assisted monitoring)
  15. 15. Practically what is done in OT ??? • There are 3 (three) phases: – Induction, Maintenance and Recovery • Induction (Induction time): It is the period of time which begins with the beginning of administration of anaesthesia to the development of surgical anaesthesia (Induction time). – Induction is generally done with IV anaesthetics like Thiopentone Sodium and Propofol • Maintenance: Sustaining the state of anaesthesia. Usually done with an admixture of Nitrous oxide and halogenated hydrocarbons • Recovery: At the end of surgical procedure administration of anaesthetic is stopped and consciousness regains (recovery time)
  16. 16. Pharmacokinetics of inhalation anaesthetics: Pathway for anaesthetics: • Inhalation anaesthetics: Depth of anaesthesia depend on MAC and Partial Pressure of the gas in Brain • Passes through a series of tension gradients
  17. 17. Factors affecting Pharmacokinetics of inhalation GA Factors affecting PP of anaesthetics in Brain: 1. PP of anaesthetic in the inspired gas 2. Pulmonary ventilation – can be manipulated 3. Alveolar exchange - perfusion 4. Solubility of anaesthetic in blood - Blood: gas partition coefficient - important 5. Solubility in tissues – Halothane 6. Cerebral blood flow – CO2 inhalation
  18. 18. Stop Signs !!! • Drug Interactions: – Cardiac Drugs – CNS Drugs – Respiratory depressants • Adverse Reactions: – Exaggerated patient response to a normal dose – Malignant Hyperthermia – Liver Necrosis – rash, fever, jaundice and altered liver function
  19. 19. Nursing Process !! • Assessment: – Prescription, non-prescription or any other Drug History – Allergies – Other risk factors – smoking, obesity, alcoholism, CVS/renal/respiratory diseases – Vital signs and laboratory data • Interventions: – Explain preoperative and post operative recovery – Postoperative requirements – early ambulation, deep breathing, coughing, leg exercises, fluid balance and urine output – Monitor vital signs – Response to pain medication
  20. 20. Intravenous anaesthetic agents • Drugs: – Thiopentone, Methohexitone sodium, propofol and etomidate – Diazepam, Lorazepam, Midazolam – Ketamine – Fentanyl • Kinetics: Highly lipid soluble, distributed widely and metabolized in liver • MOA: – GABA A receptor gated chloride channel opening – Opioid receptors • Uses: In short surgical procedures • Ketamine: Dissociative – irrational Behaviour !!!!
  21. 21. Intravenous anaesthetic agents – contd. • Adverse Reactions: – CNS depression – Respiratory depression – Coughing – Hiccups – Muscle twitching • Nursing Process: Same as Inhalation Anaesthetics
  22. 22. Local Anaesthetics
  23. 23. LA – contd. • MOA: – Blocking of Nerve conduction – by blocking Voltage gated Na+ channel • Uses: – To prevent and relieve pain caused by medical procedures, diseases or injuries – Severe pain when analgesics cannot relieve – In elderly and debilitated patients – where GA cannot be used – For vasoconstriction along with Adrenaline • ADRs: – CNS: Anxiety, restlessness, disorientation, confusion, dizziness and muscle twitching etc. – CVS: Bradycardia and Arrhythmia
  24. 24. + + - - + + -- - - + + + + - - Na+ + ++ + - - - - Resting (Closed**) Open (brief) inactivated Very slow repolarization in presence of LA LA receptor LA have highest affinity for the inactivated form Refractory period Mechanism of LA - lignocaine
  25. 25. LA - Nursing Process • Assessment: – Allergy and Risk factors – Vital signs • Planning: – Risk of Injury to the patient be minimized – Patient will acknowledge a reduction in pain • Interventions: – Explain the purpose of therapy – Monitor vital signs – Monitor the patient`s response to medication
  26. 26. Take Home • Every patient who undergoes sedation or anesthesia should have a thorough physical and laboratory exam which should be documented in the medical record.
  27. 27. Thank you

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