Surgical Anesthesia

History of Anesthesia Derived from the Greek word ‘Anaisthesis’ meaning “lack of sensation”. Defined today as the process used to relieve pain and suffering during surgical intervention.

History of Anesthesia Early use of anesthetic substances included coca leaves and opium. Ether was used extensively throughout the 1800’s with much success. These practices set the groundwork for the science of anesthesia leading to newer, safer, and better agents used today.

History of Anesthesia

Anesthesia Techniques Optimal anesthesia addresses the following areas: Hypnosis Anesthesia Amnesia Muscle relaxation Patient positioning Homeostasis of vital functions

Anesthesia Techniques Anesthetic agents can be administered in two ways: General anesthesia Altering the patients level of consciousness. Nerve conduction blockage Preventing sensory nerve conduction

Anesthesia Techniques Choice of the type of anesthesia used varies from case to case, keeping the patients safety in mind.

Anesthesia Techniques ASA risk classifications: Class 1 No organic, physical, biochemical, or psychological disturbance. Class 2 Mild to moderate systemic disturbance. Smokers, controlled hypertension, diabetes, mild obesity.

Anesthesia Techniques ASA risk classifications: Class 3 Severe systemic disturbance or disease. Angina, post MI, massive obesity. Class 4 Severe systemic disturbance that are life threatening. Congestive heart failure, respiratory disease.

Anesthesia Techniques ASA risk classifications: Class 5 Patient has little chance for survival. Class 6 Brain dead, organ procurement. Emergency modifier Applied for emergency surgery.

General Anesthesia Involves an alteration in the patients perception of his environment by alterations in the level of consciousness. Agent inhalation Agent injection Agent instillation

General Anesthesia Stages of general anesthesia: Stage I Amnesia stage beginning with initial administration of agent until loss of consciousness.

General Anesthesia Stages of general anesthesia: Stage II Excitement stage from loss of consciousness to return of regular breathing and loss of eyelid reflex. Vomiting and laryngospasm may be seen. May be passed through rapidly by IV induction agent.

General Anesthesia Stages of general anesthesia: Stage III Surgical anesthesia stage. Patient is unresponsive to pain and sensation. Hearing is the last sense lost. Optimum for surgical intervention.

General Anesthesia Stages of general anesthesia: Stage IV Overdose stage. Dilated, non-reactive pupils. If untreated, may lead to circulatory failure or death.

General Anesthesia Phases of general anesthesia: Induction phase Alteration from a conscious to unconscious state. Use of IV or inhaled agent. Airway must be managed. Hearing is the last sense obtunded, keep the room quiet.

General Anesthesia Phases of general anesthesia: Maintenance phase Surgical intervention phase Anesthesia provider must closely monitor all vital functions and adjust anesthetic levels as needed.

General Anesthesia Phases of general anesthesia: Emergence phase Goal is to have the patient as awake as possible at the end of surgery. Reversal agents may be needed. Patients may be extubated when respiratory rate and gag reflex return. Monitor for hypothermia.

General Anesthesia Phases of general anesthesia: Recovery phase Patient returns to optimum level of consciousness and well being. PACU

General Anesthesia Advantages Patient is unaware of activities and noises during surgery. Respiration rate and aspiration risks are controlled. Muscle relaxation is easily achieved.

General Anesthesia Risks and complications Aspiration of gastric contents could occur during the induction or emergence phase causing aspiration pneumonia. Patients must be NPO for adequate number of hours prior to surgery. Cricoid pressure (Sellick’s maneuver)

General Anesthesia Cricoid pressure (Sellick’s maneuver)

General Anesthesia Risks and complications Laryngospasms and bronchospasms cause rigidity in the upper respiratory tract resulting in the patient’s inability to move air in and out of the lungs. Caused by trigger of gag reflex. Treated with positive pressure or succinylcholine. (neuromuscular blocker)

General Anesthesia Risks and complications Malignant Hyperthermia a potentially fatal hyper metabolic state of muscles. Calcium deficiency causes skeletal muscles to contract and become rigid. Heat, CO2, and lactic acid buildup causes a rapid increase in body temperature.

General Anesthesia Risks and complications MH can be triggered by use of succinylcholine, curare, and halogenated inhalation agents. Staff should be familiar with signs and symptoms and know the location of supplies and treatment protocol.

General Anesthesia Risks and complications Treatment includes discontinuing the anesthetic agent ASAP. Dantrolene is given by IV. Other treatments include cooling the body by ice or chilled lavage. Sodium bicarbonate may be given to assist with acidosis.

General Anesthesia Risks and complications Mild or severe allergic reactions. Anaphylaxis reactions are the most serious and may lead to respiratory and vascular collapse. Strict adherence to identified patient allergies are a must.

General Anesthesia Risks and complications Patients in general anesthesia are also at risk for: Shock Cardiac dysrhythmias Cardiac arrest

Anesthetic Agents Inhalation agents Agents inhaled and pass to the blood stream via pulmonary function. Oxygen Nitrous oxide Waste gases

Anesthetic Agents Inhalation agents Volatile agents are liquids whose potent evaporative vapors produce general anesthesia. Lowering CNS, respiratory, cardiovascular, and muscle activity.

Anesthetic Agents Inhalation agents Halothane Enflurane Isoflurane Desflurane Sevoflurane

Intravenous agents Provide direct access to the bloodstream and agents act quickly and are metabolized by the liver and kidneys. Induction agents Dissociative agents Opioids Sedatives/Tranquilizers Neuromuscular blockers Adjunctive agents Antimuscarinic (Anticholinergic) agents

Intravenous agents Induction agents Medications used to permit rapid and pleasant transition from stage 1 to stage 3. Produce a sedation and amnesia. May be used to maintain general anesthesia.

Intravenous agents Induction agents Propofol Nicknamed “Milk of Amnesia”, due to its milky color. Sedative/hypnotic agent with no “hang over” affects May produce discomfort at IV site because of its alkaline nature. Contraindicated for patients with head trauma.

Intravenous agents Induction agents Etomidate (Amidate) Post-op vomiting may occur. Thiopental sodium (Pentothal sodium) No anesthesia or muscle relaxation. Leaves patient with “hang over” affect. Methohexital sodium (Brevital) Very quick onset

Intravenous agents Dissociative agents Interrupt pathways to the brain. Patients may appear awake, but are unaware of their surroundings. Ketamine HCL (Ketalar) Does not relax reflexes. Increased salivation, Intracranial/Intraocular pressure. May cause morbid hallucinations or “flash backs”.

Intravenous agents Opioids Decrease pain impulses and a feeling of euphoria. Schedule II narcotics Morphine sulfate Meperidine (Demerol) Fentanyl citrate (Sublimaze) Sufentanil citrate (Sufenta) Alfentanil HCL (Alfenta) Remifentanil HCL (Ultiva)

Intravenous agents Naloxone HCL (Narcan) Reverses opioid affects or overdose. May lead to rapid onset of pain.

Intravenous agents Benzodiazepines (Sedative/tranquilizers) Reduces anxiety and apprehension preoperatively. Produces amnesic effects. Diazepam (Valium) Midazolam (Versed) Droperido (Inapsine)

Intravenous agents Neuromuscular blockers Interfere with the passage of impulses from motor nerves to skeletal muscles. Monitored by a nerve stimulator Two major categories: Depolarizing agents Nondepolarizing agents

Intravenous agents Depolarizing agents Mimics a release of acetylcholine across the neuromuscular junction, causing muscles to contract then followed by a period of muscle fatigue. “Fasciculation” Succinylcholine

Intravenous agents Non-depolarizing agents Work by competing for synapse receptor sites at the neuromuscular junction, preventing acetylcholine from stimulating muscle contraction. Short, intermediate, and long acting agents.

Intravenous agents Non-depolarizing agents Mivacurium chloride (Mivacron) Vecuronium bromide (Norcuron) Rocuronium bromide (Zemuron) Atracurium besylate (Tracrium) Cisatracurium besylate (Nimbex) Tubocurarine chloride (Curare) Pancuronium bromide (Pavulon)

Intravenous agents Antimuscarinic agents Used to limit undesirable parasympathetic nervous system responses. Salivation Bradycardia Atropine sulfate Glycopyrrolate (Robinul)

Intravenous agents Nonsteroidal Anti-Inflammatory agents Ketorolac (Toradol) Given IM for moderate pain control. Gastric Acid Management Bicitra, Tagamet, Zantac, Reglan Alter PH and reduce gastric volume. Antiemetic Reglan, Zofran, or Inapsine Prevent or treat nausea and vomiting.

Adjunctive Treatments Induced Hypothermia Deliberate lowering of the body’s core temperature to reduce oxygen demand and waste product formation. Light Hypothermia = 98.6oF- 89.6oF Moderate Hypothermia = 89.6oF- 78.8oF Deep Hypothermia = 78.8oF- 68oF Profound Hypothermia = 68oF- below

Anesthesia Equipment The primary goal during anesthesia is to keep the patient as safe as possible throughout the procedure. The anesthesia machine and other equipment allow the surgical team to promote homeostasis, identify and physical changes, and provide early intervention, before it can become life threatening.

Anesthesia Equipment Anesthesia machine Inhalation agent delivery system Vaporizers Respiratory support equipment Monitoring devices Anesthesia circuit Tubing system providing inhalation of anesthetic agents.

Anesthesia Equipment Airway Delivery/Maintenance Devices Endotracheal (ET) tubes Provides patient’s airway. Placed through the patients nose or mouth, between the vocal cords, and into the trachea. May have ballooned cuff. Place with the assistance of a stylet.

Anesthesia Equipment Airway Delivery/Maintenance Devices McGill forceps Aid in placement of nasogastric/ nasotracheal tubes. Laryngoscope Lighted device to expose the glottis and assist in ET tube placement.

Anesthesia Equipment

Anesthesia Equipment Airway Delivery/Maintenance Devices Laryngeal Mask Airway (LMA) Provides simple effective airway forming a low pressure seal around the laryngeal inlet. Oropharyngeal and Nasal Airways Provides unobstructed airway around a relaxed tongue.

Anesthesia Equipment LMA Oral Airway Nasal Airway

Anesthesia Equipment Hypothermia/Hyperthermia Devices Bair Hugger Warming device that uses warm air blown into a special blanket placed over the patient. Secured with adhesive strips. Various sizes and shapes.

Anesthesia Equipment

Anesthesia Equipment Hypothermia/Hyperthermia Devices Warming/Cooling Blankets Fluid Warming Devices Rapid Infusion Pump Infusion Control Devices

Anesthesia Equipment Monitoring Devices Electrocardiogram (EKG) Noninvasive method to monitor the rate, rhythm, and electrical conduction of the heart. Placement of electrodes BP Monitor Arterial/Venous Catheterization

Anesthesia Equipment Monitoring Devices Temperature Monitors Skin surface monitor Invasive monitoring Esophageal, bladder, rectal probes.

Anesthesia Equipment Monitoring Devices Pulse Oximeter Noninvasive assessment of the hemoglobin saturation levels. Uses a pulsing absorption of light. Placed on the fingertip, toes, earlobe, or bridge of the nose. No nail polish.

Anesthesia Equipment

Anesthesia Equipment Monitoring Devices Bispectral Index Monitor Capnography Provides breath by breath analysis of expired CO2 (end tidal CO2) Spirometry Oxygen Analyzer

Anesthesia Equipment Monitoring Devices Stethoscope Placement of ET tube. Doppler Uses ultrasound to assess vessels. Peripheral Nerve Stimulator Assess level of neuromuscular blocker. Arterial Blood Gas (ABG)

Nerve Conduction Blockade Used to prevent initiation or transmission of impulses along a nerve pathway. Provides lack of sensation distal to, or adjacent to the injection site. Local and Regional anesthetics Amino Amides Amino Esters

Nerve Conduction Blockade Amino Amide Lidocaine HCL (Xylocaine) Most widely used. Rapid onset. Mepivacaine HCL (Carbocaine) Bupivacaine HCL (Marcaine) 4x as strong as Lidocaine. Long onset, but long acting. Etidocaine HCL (Duranest)

Nerve Conduction Blockade Amino Ester Cocaine HCL Topical anesthetic of the upper aerodigestive tract mucosa. Procaine HCL (Novocaine) Tetracaine HCL (Pontocaine)

Nerve Conduction Blockade Adjunctive agents Hyaluronidase (Wydase) Added to assist local anesthetic to distribute to the subcutaneous tissues. Retrobulbar Epinephrine (Adrenalin) Vasoconstrictor Not to be used on digits or penis.

Nerve Conduction Blockade Topical Anesthesia Provides anesthesia on mucous membranes of the upper aerodigestive tract, urethra, vagina, rectum and skin. Cryoanesthesia Ethyl chloride Lidocaine Cocaine

Nerve Conduction Blockade Local Anesthesia Injection of a nerve conduction blocking agent into surrounding tissues. Onset and duration depend on medication used. Epinephrine Re-administration of addition medication may be necessary.

Nerve Conduction Blockade Regional Anesthesia Administration of anesthetic along a major nerve pathway. Nerve plexus block Bier block Spinal Epidural Caudal

Nerve Conduction Blockade Nerve Plexus Block Injection of an anesthetic solution in an area of a major nerve plexus. Brachial plexus Used with IV sedation, it permits use of a lower dose.

Nerve Conduction Blockade Bier block Used on procedures of the arm of 1-hour duration or less. Double cuffed tourniquet is applied to the arm and anesthetic is injected into a vein below the tourniquet. Arm is exsanguinated and tourniquet is inflated, containing the anesthetic and making for a “bloodless” surgery.

Nerve Conduction Blockade

Nerve Conduction Blockade Spinal (Intrathecal block) Injection of anesthetic agent into the subarachnoid space. Produces a loss of sensation below the diaphragm. Most commonly used agent is tetracaine HCL. Lidocaine HCL Procaine HCL

Nerve Conduction Blockade Spinal (Intrathecal block) Circulator assists placing patient in desired position and stands by to help maintain it. Lower lumbar area is cleansed and draped. Local anesthetic is injection to provide comfort. Spinal needle is placed into the subarachnoid space. Agent is injection and patient is positioned for surgery.

Nerve Conduction Blockade Factors affecting spinal anesthesia: Patient cooperation Position Exposure to the intervertebral spaces. “Mad cat” position Agent baricity Specific gravity Hyperbaric = toward gravity Isobaric = move away from gravity

Nerve Conduction Blockade Advantages of Spinal Anesthesia Patient remains conscious and in control of their own airway. No irritation to the upper respiratory tract. Bowel contraction. Excellent muscle relaxant.

Nerve Conduction Blockade Disadvantages of Spinal Anesthesia Lowering of blood pressure. Treated by large dose of IV fluids. Spinal headache Meningeal layer irritation due to a drop in CSF pressure. Patient may require a blood patch.

Nerve Conduction Blockade Epidural Anesthesia Administration of an anesthetic agent via an indwelling catheter above the dura mater and is absorbed into the CSF. Permits re-administration of additional agent as needed. Patient position and baricity have little affect.

Nerve Conduction Blockade

Non-Traditional Anesthesia Hypoanesthesia Using hypnotherapy to alter the patients level of consciousness. Acupuncture Intense electrical stimulation in specific body areas to alter the perception of pain. Body’s use of endorphins.

Team Member Roles During Anesthesia Preoperative Induction and Maintenance Spinal anesthesia Post anesthesia Pages 250-256