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PTP 546 Module 15 Pharmacology of Anesthetics Jayne Hansche Lobert, MS, RN, ACNS-BC, NP Lobert 1 Pharmacology of Anesthetics • Anesthetic Agents – Characteristics • • • • • • Produce loss of consciousness and sensation Provide amnesia Relax skeletal muscles Inhibit sensory and autonomic reflexes Possess minimal side effects Rapid onset of anesthesia Lobert 2 Pharmacology of Anesthetics • Stages of Anesthesia – Stage I: Analgesia • Somewhat aware but begins to lose somatic sensation – Stage II: Excitement/Delirium • Appearance of agitation and restlessness – Stage III: Surgical Anesthesia • Overall goal is to reach this stage quickly and maintain this stage for the duration of the surgery – Stage IV: Medullary Paralysis • Reduction of Vitals: cessation of spontaneous respirations; BP issues cardiopulmonary collapse • Would require intensive support Lobert 3 Pharmacology of Anesthetics • General Anesthetics – Inhaled Anesthetics • Volatile Liquids: Desflurane; Isoflurane • Gas: Nitrous Oxide – Intravenous Anesthetics • • • • • Barbiturates Benzodiazepines Opioids Ketamine Propofol Lobert 4 Pharmacology of Anesthetics • Pharmacokinetics of General Anesthesia – Route: • IV or Inhaled – Distribution: • Widely distributed throughout body • Highly lipid soluble deposits in adipose tissues – Metabolism & Excretion: • Via Liver and Lungs Lobert 5 Pharmacology of Anesthetics • General Anesthetics – Action: inhibit neuronal activity throughout the CNS unconsciousness and amnesia; produces immobility and inhibits motor responses to painful stimuli – Therapeutic Effect: anesthesia allows for surgical intervention – Side Effects: residual effects may be associated with length of anesthesia, dose, age, adipose tissues Lobert 6 Pharmacology of Anesthetics • Local Anesthetics – Ex: Bupivacaine (Marcaine); Lidocaine (Xylocaine) • Action: drug produces a loss of sensation in the specific body part or region • Therapeutic Effect and Clinical Use: – Topical Administration & Transdermal administration – Infiltration anesthesia: injection into local tissues to be numbed – Peripheral nerve block: brachial plexus catheters with ropivacaine during and following shoulder arthroplasty – Central neural blockade: injectio into epidural/intrathecal/ spinal sac – Sympathetic block – Intravenous regional anesthesia/block: ex: veins drained and filled with anesthetic: numbing distal to extermity, example hand surgery. Lobert 7 Pharmacology of Anesthetics • Adjuvants in General Anesthesia – Preop Medications • Barbiturates: decreases level of consciousness very quickly • Benzodiazepines: decrease anxiety • Opioids • Antihistamines • Antacids: position in surgery, no acid refulx. • Anticholinergics- decrease secretions to keep from aspirating on own spit. Lobert 8 Pharmacology of Anesthetics • Adjuvants in General Anesthesia – Neuromuscular Blockers (paralyzing agents) • Nondepolarizing Blockers – Pancuronium (Pavulon); Vecuronium (Norcuron) • Depolarizing Blockers – Succinylcholine (Anectine) – Action: complete muscle paralysis; no analgesia; no anesthesia. – Side Effects: residual paralysis Lobert 9 Pharmacology of Anesthetics • Local Anesthetics – Side Effects: • Extension of loss of motor function • Potential for systemic effect – CNS symptoms somnolence, confusion, agitation and excitation – CV symptoms Lobert 10