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Principles of Anesthesia ST210 Concorde Career College Objectives • Assess the action, uses, and modes of administration of drugs and anesthetic agents used in the care of the surgical patient • Recognize general terminology and abbreviations associated with anesthesia • Recognize the side effects and contraindications for the use of various anesthetic drugs Objectives • Interpret factors that influence anesthesia selection for individual patients • List the equipment used during anesthesia administration • Analyze how sterile technique is used in relation to anesthesia procedures • Compare and contrast the roles of the surgical technologist and circulator during the administration of anesthesia Definitions Anesthesia - From the Greek meaning lack of sensation; particularly during surgical intervention. Definitions • Review • • • • • • HYPNOSIS ANESTHESIA AMNESIA MUSCLE RELAXATION POSITIONING HOMEOSTASIS Anesthesia History Timeline • 1500s: Coca leaves used as local anesthetic during trephination of the skull • 1725: Ether was discovered by Spanish chemist Raymundus Lillius • 1800s: Social use of ether - “ether frolics” • 1842: Crawford W. Long may have been the first to use ether for surgical pain control, but did not publish his findings until 1848 Anesthesia History Timeline • 1846: William T.G. Morton performed surgery at Mass General Hospital in front of an audience – First Surgical Use of Anesthetics – Click Here – Ether Dome: Mass General Hospital • 1905: Long Island Society Anesthetists (LISA) formed • 1936: LISA changed name to ASA (American Society of Anesthesiologists) Anesthesia History Timeline Anesthesia History Timeline Anesthesia History Timeline Anesthesia Administration Two primary methods of anesthesia administration: 1. Inhalation Agents – Typically for General Anesthesia 2. Injectable Agents – Typically for Nerve Conduction Blockade, or – Regional Anesthesia General Anesthesia Alteration in the patient’s level of consciousness (patient is “asleep”) Accomplished by: • Agent inhalation • Agent injection • Agent instillation Nerve Conduction Blockade Prevent initiation of conduction of nerve impulses along a nerve pathway (patient is “awake”) Anesthesia Selection Factors that affect selection of the type of anesthesia: • • • • • Planned procedure and estimated duration Patient position Age, size, and weight of the patient Patient status (emotional, mental, and physical) General health of the patient (comorbid conditions) Anesthesia Selection Factors that affect selection of the type of anesthesia: (continued) • • • • • Medication status Allergy status History of substance abuse Emergency conditions Preference (surgeon, anesthesia provider, patient) ASA Risk Classification System • Class 1 – No organic, physiological, biochemical, or psychiatric disturbance • Class 2 – Mild to moderate systemic disease or disturbance (e.g., controlled hypertension or diabetes, asthma, anemia, smoking, mild obesity, age – less than 1 or greater than 70) ASA Risk Classification System • Class 3 – Severe systemic disease or disturbance (e.g., stable angina, previous MI, poorly controlled hypertension or diabetes, symptomatic respiratory disease, massive obesity) • Class 4 – Severe (life threatening) systemic disease or disturbance (e.g., unstable angina, CHF, debilitating respiratory disease, hepatorenal failure) ASA Risk Classification System Class 5 – Moribund Class 6 – Brain dead E – Emergency modifier Roles of the Surgical Team Members (refer to the tables on pp. 257-261) • Preoperative case management duties • Intraoperative case management duties • Postoperative case management duties Anesthesia Evaluation & Preparation Preanesthetic evaluation and preparation processes • • • • Preoperative routine Preoperative education Patient possessions Preoperative procedures Preoperative Routine – Enema – Nail polish and makeup – Hygiene (shower and shave) – Attire – Sedation – Call to the OR – Family visit – Identification, chart, consent, transportation, transfer... Anesthesia Equipment Equipment and techniques used to monitor the patient • • • • • • Blood pressure O2 Sat Temperature I&O Heart BIS • Respiration – SARA • Doppler • Peripheral Nerve Stimulator • ABG Anesthesia Equipment Equipment and techniques used to monitor the patient Blood Pressure Sphygmomanometer (with stethoscope) Anesthesia Equipment Equipment and techniques used to monitor the patient O2 Sat Pulse Oximeter Anesthesia Equipment Equipment and techniques used to monitor the patient Temperature Thermometer Esophageal Stethoscope with temperature probe Anesthesia Equipment Equipment and techniques used to monitor the patient I&O Intake and Output Anesthesia Equipment Equipment and techniques used to monitor the patient Heart Apical Stethoscope Earpiece Anesthesia Equipment Equipment and techniques used to monitor the patient Heart Electrocardiogram Electrodes Anesthesia Equipment Equipment and techniques used to monitor the patient Heart Electrocardiogram Leads Anesthesia Equipment Equipment and techniques used to monitor the patient Heart Electrocardiogram (ECG) Anesthesia Equipment Equipment and techniques used to monitor the patient BIS Monitor (Bispectral Index) Anesthesia Equipment Equipment and techniques used to monitor the patient Respiration SARA (System for Anesthetic and Respiratory Analysis) Anesthesia Equipment SARA is capable of several functions including: • Capnography • Spirometry • Oxygen analysis Anesthesia Equipment Equipment and techniques used to monitor the patient Doppler Anesthesia Equipment Equipment and techniques used to monitor the patient Peripheral Nerve Stimulator Anesthesia Equipment Equipment and techniques used to monitor the patient ABG (Arterial Blood Gas) Methods of Anesthetic Administration • General – Balanced – Neuroleptanalgesia • Nerve Conduction Blockade – Regional – Local – Topical Common Anesthetic Agents • Inhalation Agents – Oxygen – Nitrous oxide – Waste gases Common Anesthetic Agents Oxygen • Inhalation agent • Not anesthetic agent • Necessary for life Common Anesthetic Agents Nitrous Oxide • Produces analgesia and amnesia • Produces little muscle relaxation • Decreases myocardial contractility and respiratory function Common Anesthetic Agents Waste gas scavenger system Common Anesthetic Agents Volatile Agents • • • • Liquids with potent evaporative vapors CNS depression produces general anesthesia Myocardial and respiratory depression Decrease muscle tone Volatile Agents • • • • • Halothane (Fluothane) Enflurane (Ethrane) Isoflurane (Forane) Desflurane (Suprane) Sevoflurane (Ultane) Halothane • Rapid acting • Sweet odor • Nonirritating to the respiratory tree • Used for induction and maintenance Enflurane • • • • • Halogenated Sweet odor Rapid induction Rapid recovery Hypotension (when not surgically stimulated) • Potentiates nondepolarizing NMB Isoflurane • Rapid induction and recovery • Musty smelling • Profound respiratory depression and hypotension • Markedly potentiates NMB • Increases ICP Desflurane • Halogenated • Requires heated vaporizer • Pungent aroma • Not biotransformed in the liver Sevoflurane • Odorless • No irritation to respiratory tree • Causes bradycardia, hypotension, dysrhythmias, decreases cardiac output Intravenous Agents • Permit rapid pleasant transition from consciousness to unconsciousness • Produce marked sedation and amnesia • Produce hypotension and respiratory depression • Some induction agents may also be used for maintenance Intravenous Agents for Induction • • • • Propofol (Diprivan) Etomidate (Amidate) Thiopental sodium (Pentothal Sodium) Methohexital sodium (Brevital) Propofol • Sedative hypnotic • Soy oil in water emulsion (inhibits microbial growth) • Induction or conscious sedation • Alkaline – irritating to the vein • Causes increased ICP and hypotension Propofol • Formulations of intravenous anesthetic propofol emulsions are provided which contain sufficiently low concentrations of soybean oil to produce a stable emulsion and simultaneously provide reduced nutrients, which inhibit microbial growth thereby providing protection against accidental microbial contamination during long-term IV infusions. In addition to the inhibition of microbial growth due to a reduction of nutrients, the formulation exhibits unanticipated additional microbial inhibition due to an increased availability of propofol. The low concentration of soybean oil also provides a formulation that reduces the chances of fat overload when administered over an extended period of time to chronically ill patients. Etomidate • Non-barbiturate hypnotic • Produces minimal cardiovascular system effects • Causes nausea, vomiting, and adrenal suppression Thiopental Sodium • Potent barbiturate • Short acting • Alkaline – irritating to the vein • Less expensive than propofol Methohexital Sodium • Similar in action to propofol and thiopental sodium • Ultrashort onset and duration of action • Ideal agent for short term loss of consciousness during nerve conduction blockade Dissociative Agents • Interrupt the associative pathways of the brain (patient appears awake, but is unaware of surroundings • Produce amnesia and profound analgesia Dissociative Agents Ketamine Hydrochloride (Ketalar) • • • • • • Most commonly used IM or IV administration Rapid induction of dissociative state Potentiated by other agents (narcotics/barbiturates) Increases muscle tone Increases ICP and IOP Opiate/Opioids • Narcotic (Class II) analgesics (decrease pain impulse transmission from CNS and spinal cord receptors) • Also produce sedation • Produce euphoria and decrease anxiety • High doses lead to unconsciousness and respiratory depression Opiate/Opioids • • • • • • Morphine sulfate Meperidine (Demerol) Fentanyl citrate (Sublimaze) Sufentanil citrate (Sufenta) Alfentanil hydrochloride (Alfenta) Remifentanil hydrochloride (Ultiva) Narcotic Antagonists • Antagonize or reverse narcotic effects • Increased level of consciousness seen in 1-2 minutes • Naloxone hydrochloride (Narcan) Benzodiazepines • Sedative tranquilizers • Reduce anxiety/apprehension • Adjunct to general anesthesia (reduce amount and concentration of other agents) • Do not produce analgesia Benzodiazepines • Diazepam (Valium) • Midazolam (Versed) • Droperidol (Inapsine) Benzodiazepine Antagonist • Flumazenil (Mazicon) – Reverses the sedative effects, but may not reverse the amnesia effects – May cause convulsions – Rebound sedation and respiratory depression may occur Neuromuscular Junction Neuromuscular Junction Review • http://www.wisconline.com/objects/ViewObject.aspx?ID=AP28 04 Neuromuscular Junction Neuromuscular Blockers (NMBs) • Skeletal muscle relaxants (cause weakness – paralysis) • Interfere with passage of impulses from motor nerves to skeletal muscles • May use only one dose or re-administer throughout procedure Neuromuscular Blockers (NMBs) • Used to relax the jaw for ease of endotracheal intubation • Muscles of respiration are affected (mechanical ventilation required) • Surgical site relaxation to allow for tissue retraction Neuromuscular Blockers (NMBs) Depolarizing Agents • Mimic release of acetylcholine across the neuromuscular junction • Causes muscle contraction (fasciculation) followed by a period of muscle fatigue • Patient may experience postprocedure muscle ache Neuromuscular Blockers (NMBs) Depolarizing Agents • Metabolized by plasma cholinesterase in the synapse reversing the effect of the agent • NO pharmacologic antagonist Neuromuscular Blockers (NMBs) Depolarizing Agents • Succinylcholine (Anectine) – Most commonly used – Short acting – Known triggering agent for MH • Decamethonium (Syncurine) Neuromuscular Blockers (NMBs) Nondepolarizing Agents • • • • • Compete for post synaptic receptors Prevents stimulation of muscle contraction Duration (short, intermediate, long) Spontaneous recovery may occur Pharmacologic antagonist available – Edrophonium chloride (Tensilon) – Neostigmine (Prostigmin) Neuromuscular Blockers (NMBs) Nondepolarizing Agents Short Acting • Mivacurium chloride (Mivacron) • Vecuronium bromide (Norcuron) • Rocuronium bromide (Zemuron) Neuromuscular Blockers (NMBs) Nondepolarizing Agents Intermediate Acting • Atracurium Besylate (Tracrium) • Cisatracurium besylate (Nimbex) Neuromuscular Blockers (NMBs) Nondepolarizing Agents Long Acting • Tubocurarine chloride (Curare) • Pancuronium bromide (Pavulon) • Metocurine iodide (Metubine) Antimuscarinic (Anticholinergic) • Used to limit salivation and bradycardia • Two commonly used agents – Atropine sulfate – Glycopyrrolate (Robinul) NSAIDs Nonsteroidal Anti-Inflammatory Agents • Aid in pain management • Main agent – Ketoralac (Toradol) – May be given IM intraoperatively to aid in emergence and recovery pain management Gastric Acid Management • Used to alter the pH of gastric secretions and reduce gastric acid volume • Reduce the risk of stress ulcer • Agents – – – – Oral agent citric acid (Bicitra) IV agent cimetidine (Tagamet) IV agent ranitidine (Zantac) Metoclopramide (Reglan) – promotes pyloric emptying Antiemetic • Used to prevent or alleviate nausea • Agents – Droperidol (Inapsine) – Metoclopramide (Reglan) Administration Devices • • • • • Anesthesia Machine Vaporizer Anesthesia Circuit Airway Delivery/Maintenance Devices Hypo/Hyperthermia Devices Administration Devices Anesthesia Machine Administration Devices Anesthesia Cart Administration Devices Vaporizer Administration Devices Vaporizer Administration Devices Anesthesia Circuit Administration Devices Administration Devices Soda lime (calcium hydroxide) • Chemically removes carbon dioxide from the breathing circuit with the aid of activators such as sodium, potassium, and barium hydroxide Administration Devices Airway Delivery/Maintenance Devices Face Mask Administration Devices Airway Delivery/Maintenance Devices Oxygen Mask Administration Devices Airway Delivery/Maintenance Devices Nasal Cannula Administration Devices Airway Delivery/Maintenance Devices Endotracheal Tube Administration Devices Airway Delivery/Maintenance Devices Laryngoscope Administration Devices Positioning of Laryngoscope Administration Devices Cuffed ET Tube in Position Administration Devices Airway Delivery/Maintenance Devices McGill Forceps Administration Devices Airway Delivery/Maintenance Devices Oral Airway Administration Devices Airway Delivery/Maintenance Devices Nasal Airway (Trumpet) Administration Devices Airway Delivery/Maintenance Devices Nasal Airway (Trumpet) Administration Devices Airway Delivery/Maintenance Devices Tracheotomy Tube Administration Devices Airway Delivery/Maintenance Devices Tracheotomy Tube Administration Devices Airway Delivery/Maintenance Devices Laryngeal Mask Airway (LMA) Administration Devices Airway Delivery/Maintenance Devices Laryngeal Mask Airway (LMA) Administration Devices Ambu Bag Administration Devices Laryngeal Tracheal Anesthesia (LTA) Kit Hyper/Hypothermia Devices • Bair Hugger • Heating/Cooling Unit • Heat Lamp Hypo/Hyperthermia Devices Bair Hugger Hyper/Hypothermia Devices Heating/Cooling Unit (Blanket) Hyper/Hypothermia Devices Heat Lamp Positioning for Anesthesia • Supine • Lateral • Sitting General Anesthesia • Alteration in the patient’s level of consciousness • Accomplished by agent inhalation, injection, or instillation General Anesthesia Goals of General Anesthesia • • • • Lack of sensation Lack of movement Muscle relaxation Autonomic control (homeostasis) General Anesthesia (Four Stages – Depth) • Stage I – Amnesia • Stage II – Excitement • Stage III – Surgical Intervention (4 planes) • Stage IV – Overdose General Anesthesia (Four Phases) • Induction • Maintenance • Emergence • Recovery General Anesthesia Advantages Disadvantages Cricoid Pressure (Sellick’s Maneuver) Purpose – To minimize the risk of aspiration • Apply external pressure to the cricoid cartilage using the thumb and first finger to form a “V” • Pressure occludes the esophagus between the cricoid ring and the body of the 6th vertebral body • Must apply prior to induction and maintain until patient is intubated • Do NOT release pressure without permission from the anesthesia provider Cricoid Pressure (Sellick’s Maneuver) Indications • Emergency surgery shortly after eating • NPO status cannot be verified • GI bleeding • Basic life support, if needed Nerve Conduction Blockade • Anesthetic agent is used to prevent initiation and/or transmission of impulses along an individual nerve pathway or at a nerve plexus to provide anesthesia to tissues adjacent or distal to the site. Nerve Conduction Blockade • Two types of agents used to accomplish nerve conduction blockade – Amino amide group • Metabolized in the liver • Excreted by the kidneys – Amino ester group • Biotransformed by pseudocholinesterase in the plasma Nerve Conduction Blockade • Amino amide group – Lidocaine hydrochloride (Xylocaine, Lignocaine) – Mepivacaine hydrochloride (Carbocaine) – Bupivacaine hydrochloride (Marcaine, Sensorcaine) – Etidocaine hydrochloride (Duranest) Lidocaine Hydrochloride • • • • Rapid onset Moderate duration Topical, local, regional Available with or without epinephrine • Has properties that affect the heart Mepivacaine Hydrochloride • Action similar to lidocaine • Longer action than lidocaine • Does not produce significant cardiac effects Bupivacaine Hydrochloride • Four times as potent as lidocaine • Longer onset of action than lidocaine • Longer duration of effect than lidocaine • Available with or without epinephrine Etidocaine Hydrochloride • • • • Prolonged onset Long duration Highly toxic Contraindicated in children Nerve Conduction Blockade • Amino ester group – Cocaine hydrochloride – Procaine hydrochloride (Novocain) – Tetracaine hydrochloride (Cetacaine, Pontocaine) Cocaine Hydrochloride • CNS stimulant • Controlled substance • Topical application only • Produces anesthesia and vasoconstriction causing shrinkage of mucous membranes Procaine Hydrochloride • Similar properties to cocaine • Less toxic than cocaine • SC, IM, or intrathecal Tetracaine Hydrochloride • Slow onset • Prolonged duration • Primarily used as a topical agent Nerve Conduction Blockade Adjunctive Agents • Influence onset and duration of action • Two common agents – Hyaluronidase (Wydase) – Epinephrine (Adrenalin) MAC (Monitored Anesthesia Care) • Provides monitoring, sedation, analgesia, and amnesia • Used in conjunction with nerve conduction blockade Nerve Conduction Blockade Types of Nerve Conduction Blockade • Topical • Local • Regional Topical Anesthesia • Placement of a nerve conduction blocking agent onto a tissue layer (skin or mucous membrane) • Anesthesia is limited to the area in contact with the anesthetic agent • In addition to pharmaceutical agents, cryoanesthesia is another example of topical anesthesia Local Anesthesia • Placement of a nerve conduction blocking agent onto a tissue layer • Only the nerve or nerves that supply that limited (localized) area are affected Regional Anesthesia • Nerve conduction blocking agent is injected along a major nerve pathway blocking conduction of impulses from all tissue (the entire region) distal to the injection site • Examples of regional anesthesia include: – – – – – Bier Block Nerve Plexus Block Spinal Epidural Caudal Bier Block • Provides anesthesia to the distal portion of an extremity • Used on procedures expected to last one hour or less • Procedure is as follows: – – – – – IV catheter is inserted Double cuffed tourniquet is applied Exsanguination is achieved with the use of an Esmarch bandage Proximal cuff of tourniquet is inflated Nerve conduction blocking agent is injected intravenously distal to the tourniquet – Distal cuff of tourniquet may be inflated and then the proximal cuff may be deflated Nerve Plexus Block • Anesthetic solution is injected at a major nerve plexus – usually located at the base of a structure. For example the brachial plexus is at the base of the arm. Spinal (Intrathecal) Block • Anesthetic solution is injected into the subarachnoid space (into the CSF) • Provides loss of sensation below the diaphragm (patient should be able to breathe independently) Epidural Block • Anesthetic solution is injected in the epidural (outside the dura) space and is absorbed into the CSF through the dura • Provides loss of sensation below the diaphragm (patient should be able to breathe independently) Caudal Block • Type of epidural that is administered with the patient in the lithotomy position. • Agent is injected into the epidural space of the sacral canal • Used primarily in obstetrics Nerve Conduction Blockade Advantages Disadvantages • Patient is awake • May be used to avoid undesirable cardiac and respiratory side effects • Recovery time from anesthesia is decreased • Patient is awake • Patient maintains sensory awareness • Patient retains ability to move • Positioning may be difficult to maintain Postanesthesia Care (Recovery) • May occur in the PACU or the ICU • Duration approximately 1 hour or longer, if necessary – Patient is transferred or discharged when ready • Patient is monitored • Ventilatory support is provided, as needed • Medications (e.g., analgesic, antibiotic) and fluids (e.g., blood) are provided as needed • Dressings are maintained • Emotional support provided, as needed Adjunctive Anesthesia Treatments • • • • Induced Hypothermia Induced Hypotension Neuroleptanalgesia Neuroleptanesthesia Alternative (Nontraditional) Anesthesia Treatments • Hypnoanesthesia • Acupuncture