Module 8: Anesthesia (RPN20231)

MODULE 8: Anesthesia Suggested Readings Alexander’s Care of the Patient in Surgery (2022) Chapter 5 ORNAC Standards 2023 Section 3: Management of Perioperative Care p. 3-21; 3-114 – 3-...

MODULE 8: Anesthesia Suggested Readings Alexander’s Care of the Patient in Surgery (2022) Chapter 5 ORNAC Standards 2023 Section 3: Management of Perioperative Care p. 3-21; 3-114 – 3- 131 Section 4: Risk Management p. 4-11; p.4-44 – 4-47 Section 5: Exceptional Clinical Events p. 5-27 – 5-34 Learning Outcomes Understand the types of anesthesia used in the operating room. Understand the 3 Phases of General Anesthesia. Identify common anesthetic medications used in the operating room. Explain anesthetic related emergencies including malignant hyperthermia, cardiac arrest, and latex allergy. Anesthesia Definition Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for surgical procedures. The RN will complete the pre-op patient assessment and checklist, transport the patient to the operating room, apply non-invasive monitoring, and directly assist the anesthetist with the induction and intubation. Surgical Safety Checklist Briefing: The patient is on the operating table and before induction. Time-Out: Surgical pause before the first skin incision is made. Debriefing: After the surgery is complete and prior to leaving the OR. Types of Anesthesia 1. General 2. Regional/Local 3. Monitored Anesthetic Care 4. Local Anesthesia Module 8: Anesthesia  1. General Anesthesia (GA) A reversible unconscious state characterized by amnesia, analgesia, depression of the reflexes and muscle relaxation leading to a comatose, immobile state. The patient is no longer able to breathe on their own and are intubated by the anesthetist and connected to the anesthetic machine for mechanical ventilation. This can be achieved through inhalation or intravenous (IV) techniques. In pediatrics, the common administration is inhalation gases through the face mask followed by the insertion of an IV. Adults are induced with an IV but can also have a combination of inhalation and IV medications in their phases of anesthesia. Stages of General Anesthesia Stage 1: Initial dose of medication to the loss of consciousness (LOC) Stage 2: LOC to loss of reflexes (*eye lids) Stage 3: Regular breathing pattern to cessation of breathing Stage 4: Cessation of breathing to circulatory failure During Stage 2, the patient is very sensitive to sound and there should be minimal auditory of physical stimulation during this stage. This is very common in pediatrics and often thrashing may occur. Phases of General Anesthesia Induction: Begins from the administration of anesthetic medications and intubation. Continues until the patient has been positioned, prepped, and draped. Maintenance: The patient is kept asleep during the surgery by maintenance anesthetic medications. Emergence: The anesthetic medications have worn off and the patient will wake up and be extubated. Module 8: Anesthesia American Society of Anesthesia (ASA) Classification Patients are classified according to their perioperative health status. ASA Pre-Op Health Status Example Category 1 Normal healthy patient No physiologic complications. 2 Patients with mild systemic disease No functional limitations and well- controlled disease. i.e.- GERD, COPD, controlled Hypertension or Diabetes 3 Patients with severe systemic Some functional limitation; disease controlled disease of more than one system: CHF, obesity, chronic renal failure. 4 Patients with severe systemic Poorly controlled disease. disease that is a constant threat 5 Morbid patients not expected to Not expected to survive > 24 hours survive without surgery. i.e.- Sepsis 6 Declared brain-dead Organ donor Anesthetic Machines and Circuits Anesthetic machines are designed to deliver gas mixtures of oxygen, nitrous oxide and air. The gas mixture may contain a concentration of one of the volatile anesthetic agents. The anesthetic is delivered through an anesthetic circuit. All expired air from the patient is “scavenged” to an outside filter where expired anesthetic gases are removed. Closed Circuit or Circle Systems Rebreathing or Circle Systems have a “carbon dioxide absorber” which removes the expired CO2 from the patient and allows them to re-breathe the expired gases. The absorber contains a form of Soda Lyme. This is a mixture of Calcium Hydroxide (95%) and sodium hydroxide (5%) This clear dry substance changes to a purple colour once it absorbs CO2 from the expired patient. As the filter becomes more dark purple in colour, it must be changed. Module 8: Anesthesia  CO2 Absorber Pharmacological Agents Amnesia/Hypnotic Diazepam (Valium) Midazolam (Versed) Analgesia (Opioids) Fentanyl Morphine Sleep Inducing Propofol (Diprivan) Sodium Methohexitol (Brevtal) - very-short acting Thiopental (Pentothal) – not common – risk of laryngospasm Muscle Relaxants Depolarizing Skeletal Muscle Relaxant - Succinylcholine Non-Depolarizing SMR- Rocuronium, Pavulon Inhalation Gases Stored in tanks outside of the hospital and have a direct pipeline to the operating room. Each gas pipeline has a specific colour that connects to the colour coordinated attachment on the anesthetic machine. These gases include: Air Oxygen Nitrous Oxide Module 8: Anesthesia Inhalation Gases come in a liquid state and pass through a vaporizer on the anesthetic machine that changes them to a gaseous state. *Important Note: All inhalation gases ending in “ANE” can potentially trigger a Malignant Hyperthermia Event! Module 8: Anesthesia  Inhalational Advantages and Disadvantages Comments Gases Oxygen O2 Used to preoxygenate patients before Induction induction. Nitrous Oxide Given in combination with O2 (30% Induction/Maintenance N2O added) Sevoflurane Very effective for mask inductions with Induction/Maintenance children. quick inductions Desflurane Used for ambulatory care surgeries Risk of laryngospasm Causes increase in HR and decrease in BP **Airway irritant! Isoflurane Increases HR Induction/Maintenance Irritating odor Provides good relaxation Muscle Relaxants These drugs provide relaxation and have effects on skeletal muscles and little effect on smooth or cardiac muscle. Skeletal Muscle Relaxants (SMR) SMRs are a special class of drugs used in the OR for a specific purpose. They relax or paralyze the patient, including their jaw and vocal cords. Once the vocal cords are relaxed, the anesthetist can intubate using a laryngoscope blade to insert an endotracheal tube (ETT). These tubes and be cuffed or uncuffed. Note: SMRs need to be given with sleep medications (propofol), otherwise, the patient will remain awake and paralyzed! Module 8: Anesthesia They provide muscle relaxation and are also used for the maintenance phase of anesthesia during surgery. Patients coming for abdominal related surgeries will require muscle relaxation throughout the case, so the surgeon has good visualization of the abdominal cavity with the help of retractors. SMR Advantages/Disadvantages Comments Depolarizing Muscle Used for intubation Can trigger MH! Relaxant: Very fast-acting Short half-life (2-3 minutes) Cannot be given Succinylcholine Causes muscle fasciculations to patients with serum *NO reversal agent cholinesterase deficiency Non-Depolarizing Muscle Relaxants Rocuronium Longer acting Has a reversal Used for induction is Serum agent Cholinesterase deficiency or known history of MH Used for maintenance Pavulon Longest acting Has a reversal Used for long cases that require muscle agent relaxation Reversal Agents: Neostigmine (Prostigmine) is the reversal agent of choice. This can cause severe bradycardia and therefore is given with Glycopyrolate to counteract the bradycardia. ETT Intubation Module 8: Anesthesia Laryngeal Mask Airway (LMA) The LMA is also called the supraglottic airway. Placement is simple and does not require a laryngoscope or muscle relaxant. The tube rests over the larynx and is used for short surgeries in the supine position. 2. Regional Anesthetics Regional anesthesia is used for specific types of surgeries and considerations of patient populations, physiological health, pain management, length of surgery, and decreasing length of time in PACU. Local anesthetic medication is injected anywhere along a nerve pathway of the spinal cord which will provide anesthesia to specific regions of the body. Local anesthetic medications include bupivacaine, lidocaine, tetracaine, and can be plain or have epinephrine added. Types of Regional 1. Spinal 2. Epidural 3. Upper and lower extremity blocks Spinal Anesthesia The anesthetist will aseptically inject local anesthetic into the subarachnoid space (L2-L5). Module 8: Anesthesia Epidural Anesthesia Epidural anesthetic is a block used in a variety of procedures for pain management. A catheter is placed before or after surgery and is used to instill analgesic medications. The epidural space lies between the dura mater of the spinal cord. dura mater, outermost covering of the spinal cord and wall of the vertebral column. The catheter is inserted sterily. 3. Intravenous Regional/Peripheral Blocks/Injections This is a regional injection into or around a specific nerve or nerve group to depress the entire sensory nervous system of a limited, localized area. This is indicated for any procedure on the arm below the elbow or knee that will be completed in 40-60 minutes. Bier Block An extremity block that is safe and efficient for inducing surgical anesthesia in an extremity. Lidocaine plain is often used. Module 8: Anesthesia Steps: - IV is inserted in a distal vein in the surgical limb - Double tourniquet is applied to the upper arm or thigh - The arm is elevated and exsanguinated of blood with the use of an Esmark (rubber bandage) that is wrapped around the limb - Tourniquet is inflated to a pressure of 50mm Hg above the patient’s systolic blood pressure - Local anesthetic is injected in the patient’s arm - Surgery commences - Do NOT deflate tourniquet mid surgery! Blood will rush to the field and the remaining local will push to the heart causing a risk of arrest Anesthesia Complications Aspiration Aspiration can occur with patients during intubation and extubation. Likely this is result of stomach contents regurgitating in the airway. Prevention is the best treatment and strict adherence to NPO status is critical Laryngospasm A lower airway obstruction caused by the spasm of the laryngeal cords. This can occur from cord stimulation (i.e. by the suction cannula) usually on extubation. Quick response time is necessary to promote ventilation and there is a risk for reintubation if this complication occurs. Cardiac Arrest Perioperative Nurses working in an OR need to be familiar with: - Location, equipment, supplies and medications in the crash cart. - Hospital protocol for calling a code and responding to a code in the operating room. - Your role as an RPN (scrub), assist as needed, protect your sterile table, etc. Malignant Hyperthermia A rare, inherited syndrome that can cause serious complications for patients undergoing a general anesthetic. Inhalation gases and syccinylcholine are known to be triggers for MH. Signs and Symptoms: - Increased end tidal CO2 - Increased body temperature - Tachycardia - Muscle rigidity Module 8: Anesthesia Treatment – MH Cart: - Dantrolene (Dantrium) - Normal Saline IV - Sodium Bicarb - Cooling mechanisms and supplies (ice, fluids) Latex Allergy There are two types of latex allergies: Type 1- Immediate, where hypersensitivity reactions occur immediately after exposure and Type 2 – Delayed, where hypersensitivity reactions occur 1-2 days post exposure and manifest as a contact dermatitis. Patient’s who have a known allergy or sensitivity to latex should be treated with the same precautions. This includes removing all latex supplies from the OR room (tapes, gloves, drains, equipment) and ensuring the allergy alert sign is on the doors. Ideally, these patients should be scheduled the first case of the day, otherwise, a full one-hour room air exchange will have to occur between cases to ensure any potential latex remnants or particles in the air are removed. All products used in the room will be latex free. Hypothermia Perioperative Hypothermia is a common complication in surgical procedures. This means that the core body temperature is below 36 ° C. This is caused by anesthesia and heat loss due to the surgical environment. When a patient is cold, this increases their O2 consumption and causes pulmonary vasoconstriction. The patient will require higher doses of anesthesia as they will be wearing off much quicker. Preventative measures include: warming the operating room prior to patient arrival, ensuring there are warm blankets and if applicable, apply a forced air warming blanket (Bair Hugger). Module 8: Anesthesia