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Mong Lam, CRNA History Basic concepts Types of anesthesia Anesthesia machine Horace Wells and nitrous oxide William Thomas Green Morton and ether Ether Dome Certified Registered Nurse Anesthetist (CRNA) Anesthesiologist (MD) Anesthesia model or practice setting Types of anesthesia Concepts Administration & Selection Definition: “Lack of Sensation” Describes a process that is used to alleviate pain and suffering during a surgical procedure Achieved If All Of The Following Are Met: Hypnosis Anesthesia Amnesia Muscle Relaxation Optimal Positioning of Patient Homeostasis of Vital Functions Altered state of consciousness related to how the patient perceives his or her environment (surgical) and procedure (surgical) Induce sleep Can be light to fully unconscious Lack of sensation Allows for “pain-free” surgery Ranges from topical, local, regional and general (systemic) agents Lack of recall of surgical events Allows for more cooperative relaxed patient Combined with inhalation (gases) agents to produce muscle relaxation to total paralysis Allows for endotracheal intubation Facilitates exposure of tissues and organs as muscles are in a relaxed state Allows for surgical site exposure/access Allows for monitoring of the surgical patient Allows/provides physiological homeostasis Maintenance of the patient’s physiological status until surgical intervention is complete Most dangerous part of surgery is anesthesia Are inducing a state close to death without crossing that line Determining the Right Anesthetic Patient’s age, weight, and build Emotional, psychological and physical needs Type of operation and duration of operation Lab and X-ray findings Pre-existing illnesses or diseases Medications on Allergies History of drug or alcohol abuse Time since last ingested food, particularly with emergencies Based on the evaluation/assessment done preoperatively, the patient is assigned a Class # 1 through #6. This determines what kind of risk is involved for the patient for the surgical procedure about to be performed. Class 1- Patient has no previous/current physical or mental medical history Class 2- Mild to moderate disease present (controlled HTN, asthma, controlled diabetes, mildly obese, anemic, tobacco use) with no functional limitations Class 3- severe disease present (controlled angina, has had a myocardial infarction, HTN that is not controlled, respiratory disease that is causing difficulties presently, greatly obese) with functional limitations Class 4- severe disease (s) present that are life-threatening (unstable angina, CHF, respiratory disease that is debilitating, liver failure, kidney failure, myocardial infarction) Class 5- Moribound patient who is not expected to survive with or without surgery Class 6- Is brain dead/life support is being provided .This is an organ harvest or procurement. (E) Emergency Modifier- an E is added to the Class # in cases of emergency surgery Patient safety Optimal results 3 types: 1. General Focus on altering state of consciousness, awareness and pain perception 2. Nerve Conduction Blockade Focus on preventing sensory nerve impulse transmission 3. MAC (monitored anesthesia care) Combined to deliver “Balanced Anesthesia” Inhalation agents Intravenous agents Less Common: Intramuscular agents Instillation Amnesia Analgesia Anesthesia Muscle Relaxation Together provide “Balanced Anesthesia” I. Amnesia stage is lightest stage that begins with administration of agent ends with loss of consciousness Good stage for MAC II. Excitement or Delirium stage from loss of consciousness to loss of eyelid reflex and regular breathing Patient movements are uninhibited Might see vomiting, laryngospasm, hypertension, tachycardia Rarely seen except in children due to drugs that are available now to carry patients straight to stage III III. Surgical anesthesia stage from regular breathing and loss of eyelid reflex to cessation of breathing Patient unresponsive and hearing is last to go IV. Overdose stage dilated nonreactive pupils, cessation of breathing, hypotension can quickly lead to circulatory arrest if uncorrected Autonomic response is totally blocked to all stimuli 1. 2. 3. 4. 5. Preinduction begins with premed administered and ends when anesthesia induction begins in OR Induction from consciousness to unconsciousness Maintenance surgery takes place during this requires maintenance of physiological function by anesthetist Emergence as surgery is completed (start to wake up), restoration of gag reflex, extubation Recovery time during when patient returns to full consciousness begins in OR and carries into stay in PACU and beginning healing stages GA vs MAC GA vs block Types of surgery and length Age and mental status Inhalation Agents: Nitrous Oxide (N²O) Ethrane (Enflurane) Forane (Isoflurane) Halothane (Fluothane) Sevoflurane (Sevoflurane) Suprane (Desflurane) Intravenous Agents: 1. Barbiturates Short acting Anesthesia Not analgesic Pentothal (thiopental) Brevital (Methohexital) 2. Benzodiazepines Sedative and amnesiac effects Versed (Midazolam) Valium (Diazepam) Ativan (Lorazepam) 3. Individual Agent Propofol (Diprivan) Sedative/Hypnotic Anesthetic Amnesiac No Analgesia No Muscle Relaxation 4. Narcotics Maintenance of general anesthesia Anesthetic Sublimaze (Fentanyl) Alfenta (Alfentanil) Sufenta (Sufentanil) Morphine (Morphine Sulfate) 5. Muscle Relaxants (neuromuscular blocking agents) To receive endotracheal intubation, patient must be paralyzed or have relaxed muscles a. Depolarizing Agents: Initiate contractions called fasciculation example: Succinylcholine (Anectine) b. Nondepolarizing Agents: Prevent contractions examples: Curare, Pavulon, Norcuron 1. 2. 3. Includes: Topical anesthesia Local anesthesia Regional anesthesia Spinal (intrathecal) block Epidural block Caudal block Nerve plexus block Used on mucous membranes: upper aerodigestive tract, urethra, rectum, and skin Cryoanesthesia reduces nerve conduction by localized freezing with a probe connected to a cryoprecipitate unit that uses nitrogen Cryoanesthesia can also be performed with ice Lidocaine jelly Cocaine (topical only!) Most common use: sinus surgery Immediate surgical site anesthesia Affects small circumscribed area Can be injected or applied topically Lidocaine (Xylocaine) Bupivicaine (Marcaine, Sensorcaine) Procaine (Novocain) Tetracaine (Pontocaine) Mepivacaine (Carbocaine) Hyaluronidase (Wydase) facilitator/enhancer of above medications’ effects Epinephrine (Adrenalin) additive to above for vasoconstrictive properties Combination of nerve conduction blockade on topical or local level with supplementation by the anesthesia provider with analgesics, sedative-hypnotics, or amnestics Injected along a major nerve tract Nerve Plexus Block or Field Block Bier Block Spinal Epidural Caudal Block Anesthetic injected into major nerve plexus or the base of a structure Result is anesthesia of tissue innervated by that plexus Used in dental and extremities Examples: axillary, wrist, ankle, cervical plexus (CAE) Anesthetic injected to an extremity into a vein below the level of a tourniquet For arm/wrist/hand surgery that will last less than 1 hour Blood exsanguinated from extremity with an esmark, tourniquet is inflated, anesthetic given Tourniquet prevents anesthetic agent from circulating above it Tourniquet will be released slowly to allow for gradual circulation of the agent to prevent cardiovascular or CNS effects Injected into CSF in the subarachnoid space between L-3 and L-5 vertebrae For lower body procedures Onset 3-5 minutes Duration 1 ½ hours Tetracaine most common agent used Lidocaine and Procaine others used Epinephrine can prolong effect Never put patient in Trendelenburg position with spinal anesthesia Disadvantages: Hypotension Nausea and vomiting One time dose means cannot adjust Temporary or permanent paralysis Advantages: Conscious patient No respiratory irritation Bowel contraction enhances abdominal visibility Muscle relaxant effects allow easy abdominal wall retraction Injected outside of the dura in the epidural space that contains the fatty tissue Injected T-4 vertebral area and down Lower limb & perineal surgeries and obstetrics Thoracic surgeries will be placed for postop pain management Can be single dose or a catheter can be inserted to allow for redosing Type of Epidural being replaced by the Epidural Block Only difference is placement in the epidural space of the sacral canal Primarily seen with mothers in labor Drager and Datex Ohmeda Purpose Basic components: breathing circuit, ventilator, vaporizer, CO2 absorber, scavenging system Malignant hyperthermia Recall CNS depression Long term effects? Many more History Concepts Methods Machine
