PTP 546 Module 15 Pharmacology of Anesthetics Jayne Hansche Lobert, MS, RN, ACNS-BC, NP 1Lobert

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 2Lobert

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 3Lobert

Pharmacology of Anesthetics General Anesthetics – Inhaled Anesthetics Volatile Liquids: Desflurane; Isoflurane Gas: Nitrous Oxide – Intravenous Anesthetics Barbiturates Benzodiazepines Opioids Ketamine Propofol 4Lobert

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 5Lobert

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 6Lobert

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. 7Lobert

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. 8Lobert

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 9Lobert

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  10Lobert