General and Local Anesthetics

General and Local Anesthetics
Chapter 11 General and Local Anesthetics Copyright © 2017, Elsevier Inc. All rights reserved.

Copyright © 2017, Elsevier Inc. All rights reserved.
Anesthetics Drugs that reduce or eliminate pain by depressing nerve function in the central nervous system (CNS) and peripheral nervous system Copyright © 2017, Elsevier Inc. All rights reserved.

Anesthesia A state of reduced neurologic function Three types General anesthesia: complete loss of consciousness and loss of body reflexes, including paralysis of respiratory muscles. Local anesthesia: no paralysis of respiratory function; elimination of pain sensation in the tissues innervated by anesthetized nerves Balanced anesthesia Copyright © 2017, Elsevier Inc. All rights reserved.

General Anesthetics Drugs that induce a state in which the CNS is altered to produce varying degrees of: Pain relief Depression of consciousness Skeletal muscle relaxation Reflex reduction Copyright © 2017, Elsevier Inc. All rights reserved.

General Anesthetics (Cont.)
Inhalational anesthetics Volatile liquids or gases that are vaporized in oxygen and inhaled Parenteral anesthetics Administered intravenously Adjunct anesthetics Drug that enhances clinical therapy when used simultaneously with another drug Copyright © 2017, Elsevier Inc. All rights reserved.

Audience Response System Question
The nurse anesthetist is planning to use balanced anesthesia during a surgical procedure. A characteristic of this type of anesthesia is the administration of minimal doses of multiple anesthetic drugs. administration of inhaled anesthetics. intravenous (IV) administration of anesthetics. administration of anesthetics to cause muscle relaxation. Correct answer: A Rationale: The use of a combination of drugs allows less of each drug to be used and a more balanced, controlled state of anesthesia to be achieved. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Mechanism of Action of General Anesthetics
Overton-Meyer theory For all anesthetics, potency varies directly with lipid solubility. Fat-soluble drugs are stronger anesthetics than water-soluble drugs. Nerve cell membranes have high lipid content, as does the blood–brain barrier. Lipid-soluble anesthetic drugs can therefore easily cross the blood–brain barrier to concentrate in nerve cell membranes. Copyright © 2017, Elsevier Inc. All rights reserved.

Mechanism of Action of General Anesthetics (Cont.)
Varies according to drug Overall effect Orderly and systematic reduction of sensory and motor CNS functions Progressive depression of cerebral and spinal cord functions Copyright © 2017, Elsevier Inc. All rights reserved.

When assessing a patient under general anesthesia, which change to organ systems does the nurse expect? Nystagmus Skeletal muscle contraction Hypertension Decreased intracranial pressure Correct answer: A Rationale: Nystagmus can occur as a result of the use of general anesthesia. Other findings include skeletal muscle relaxation, hypotension, and increased intracranial pressure. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Indications General anesthetics are used during surgical procedures to produce: Unconsciousness Skeletal muscular relaxation Visceral smooth muscle relaxation Rapid onset; quickly metabolized Also used in electroconvulsive therapy treatments for depression Copyright © 2017, Elsevier Inc. All rights reserved.

Adverse Effects Vary according to dosage and drug used Sites primarily affected Heart, peripheral circulation, liver, kidneys, respiratory tract Myocardial depression is commonly seen Copyright © 2017, Elsevier Inc. All rights reserved.

Adverse Effects (Cont.)
Malignant hyperthermia Occurs during or after volatile inhaled general anesthesia or use of the neuromuscular blocking drug (NMBD) succinylcholine Sudden elevation in body temperature (greater than 104° F) Tachypnea, tachycardia, muscle rigidity Life-threatening emergency Treated with cardiorespiratory supportive care and dantrolene (skeletal muscle relaxant) Copyright © 2017, Elsevier Inc. All rights reserved.

Toxicity and management of overdose In large doses, anesthetics are potentially life threatening. Cardiac and respiratory arrest ultimate causes of death in an overdose. Administered in a controlled environment Copyright © 2017, Elsevier Inc. All rights reserved.

During surgery, the anesthetist notes that the patient’s heart rate is gradually increasing and becoming more irregular, the patient’s blood pressure is becoming unstable, and the patient is starting to sweat profusely. What other assessment should the anesthetist note immediately? Pupillary reactions Respiratory effort Temperature Urinary output Correct answer: C Rationale: These are indications of malignant hyperthermia, which can progress rapidly. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Dexmedetomidine (Precedex)
Alpha-2 adrenergic receptor agonist Dose-dependent sedation, decreased anxiety, and analgesia without respiratory depression Use: procedural sedation, surgeries of short duration. Short half-life, and the patient awakens quickly upon withdrawal of the drug. Sedation of mechanically ventilated patients in the intensive care unit (ICU) Copyright © 2017, Elsevier Inc. All rights reserved.

Ketamine Intravenous administration use for both general anesthesia and moderate sedation Rapid onset of action Low incidence of reduction of cardiovascular, respiratory, and bowel function Adverse effects: disturbing psychomimetic effects, including hallucinations Copyright © 2017, Elsevier Inc. All rights reserved.

Nitrous Oxide “Laughing gas” Only inhaled gas currently used as a general anesthetic Weakest of the general anesthetic drugs Used primarily for dental procedures or as a supplement to other, more potent anesthetics Copyright © 2017, Elsevier Inc. All rights reserved.

Propofol (Diprivan) Parenteral general anesthetic Used for the induction and maintenance of general anesthesia Sedation for mechanical ventilation in ICU settings Lower doses: sedative-hypnotic for moderate sedation Monitor triglycerides if administered with total parenteral nutrition Copyright © 2017, Elsevier Inc. All rights reserved.

Sevoflurane (Ultane) Fluorinated ether Widely used Rapid onset and rapid elimination Especially useful in outpatient surgery settings Nonirritating to the airway Greatly facilitates induction of an unconscious state, especially in pediatric patients Copyright © 2017, Elsevier Inc. All rights reserved.

Moderate Sedation Also called conscious sedation and procedural sedation Does not cause complete loss of consciousness and does not normally cause respiratory arrest. Combination of an IV benzodiazepine (e.g., midazolam) or propofol and an opiate analgesic (e.g., fentanyl or morphine) Anxiety and sensitivity to pain are reduced, and the patient cannot recall the procedure. Copyright © 2017, Elsevier Inc. All rights reserved.

Moderate Sedation (Cont.)
Preserves the patient’s ability to maintain own airway and to respond to verbal commands Used for diagnostic procedures and minor surgical procedures that do not require deep anesthesia Rapid recovery time and greater safety profile than general anesthesia Copyright © 2017, Elsevier Inc. All rights reserved.

Which statement regarding conscious sedation does the nurse identify as being accurate? The IV route of drug administration is commonly used in pediatric patients to provide conscious sedation. Mild amnesia is a common effect of midazolam. Patients receiving conscious sedation must be intubated with an endotracheal tube. Effects of propofol include relief of anxiety and pain. Correct answer: B Rationale: Midazolam allows the patient to relax and have markedly reduced or no anxiety yet still maintain his or her open airway and response to verbal commands while producing mild amnesia. The oral route of drug administration for conscious sedation is preferred for pediatric patients; patients receiving conscious sedation are able to maintain their own airway. Propofol will relieve anxiety; however, pain medications must be used along with propofol therapy for situations that can cause a pain response. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Local Anesthetics Also called regional anesthetics Used to render a specific portion of the body insensitive to pain Interfere with nerve impulse transmission to specific areas of the body Do not cause loss of consciousness Copyright © 2017, Elsevier Inc. All rights reserved.

Local Anesthetics (Cont.)
Topical Applied directly to skin or mucous membranes Creams, solutions, ointments, gels, ophthalmic drops, powders, suppositories Parenteral Injected intravenously or into the CNS by various spinal injection techniques Copyright © 2017, Elsevier Inc. All rights reserved.

Types of Local Anesthesia
Spinal or intraspinal Intrathecal Epidural Infiltration Nerve block Topical Peripheral nerve catheter attached to a pump containing the local anesthetic: Pain Buster and On-Q pump Copyright © 2017, Elsevier Inc. All rights reserved.

Types of Local Anesthesia (Cont.)
Lidocaine Bupivacaine Chloroprocaine Mepivacaine Prilocaine Procaine Propoxycaine Ropivacaine Tetracaine Copyright © 2017, Elsevier Inc. All rights reserved.

Drug Effects: Paralysis
First, autonomic activity is lost. Then pain and other sensory functions are lost. Last, motor activity is lost. As local drugs wear off, recovery occurs in reverse order (motor, sensory, then autonomic activity are restored). Copyright © 2017, Elsevier Inc. All rights reserved.

Indications Local anesthetics are used for: Surgical, dental, and diagnostic procedures Treatment of certain types of chronic pain Spinal anesthesia: to control pain during surgical procedures and childbirth Local anesthetics are given by: Infiltration anesthesia Nerve block anesthesia Copyright © 2017, Elsevier Inc. All rights reserved.

Indications (Cont.) Infiltration anesthesia Minor surgical and dental procedures Injection of the anesthetic solution intradermally, subcutaneously, submucosally, or intramuscularly across the path of nerves supplying target area May be given in a circular pattern around operative area Copyright © 2017, Elsevier Inc. All rights reserved.

Indications (Cont.) Infiltration anesthesia and epinephrine Some local anesthetics used for infiltration or nerve block are combined with vasoconstrictors To prevent systemic absorption of anesthetic To help confine local anesthetic to injected area To reduce local blood loss during procedure Copyright © 2017, Elsevier Inc. All rights reserved.

Indications (Cont.) Nerve block anesthesia Used for surgical, dental, and diagnostic procedures Also used for therapeutic management of pain The anesthetic drug is injected directly into or around the nerve trunks or nerve ganglia that supply the area to be numbed. Copyright © 2017, Elsevier Inc. All rights reserved.

Adverse Effects Usually limited Adverse effects result if: Inadvertent intravascular injection Excessive dose or rate of injection Slow metabolic breakdown Injection into highly vascular tissue Copyright © 2017, Elsevier Inc. All rights reserved.

“Spinal headache” 70% of patients who either experience inadvertent dural puncture during epidural anesthesia or undergo intrathecal anesthesia. Usually self-limiting Treatment: bed rest, analgesics, caffeine, blood patch Copyright © 2017, Elsevier Inc. All rights reserved.

When teaching a patient about spinal headaches, which statement will the nurse include? Spinal headaches can be prevented with bed rest after the epidural procedure. Patients who have a spinal headache should have very limited fluid intake. A graft of skin from the patient’s hand can be used to seal the leaking area causing the headache. High Fowler’s positioning should be used for patients who have a spinal headache. Correct answer: A Rationale: Adequate hydration using IV fluids is often used to increase cerebrospinal fluid pressure. A “blood patch” is often used to help close up or seal the leak. A small amount of blood is taken from the patient and injected into the epidural space. The patient should be positioned flat to prevent spinal headache, and if a patient has a spinal headache, relief is often obtained by lying flat. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Neuromuscular Blocking Drugs
Also known as NMBDs Prevent nerve transmission in skeletal and smooth muscle, resulting in muscle paralysis Also paralyze the skeletal muscles required for breathing: the intercostal muscles and the diaphragm Used with anesthetics during surgery Copyright © 2017, Elsevier Inc. All rights reserved.

Neuromuscular Blocking Drugs (Cont.)
When used during surgery, artificial mechanical ventilation is required. These drugs paralyze respiratory and skeletal muscles. The patient cannot breathe on his or her own. They do not cause sedation or pain relief. The patient may be paralyzed yet conscious. Copyright © 2017, Elsevier Inc. All rights reserved.

Typical time course of NMBD-induced paralysis muscle weakness Total flaccid paralysis: first fingers and eyes then limbs neck and trunk; finally, intercostal muscles and diaphragm NMBDs do not cause sedation or pain relief. Recovery occurs in reverse order of paralysis. Copyright © 2017, Elsevier Inc. All rights reserved.

Neuromuscular Blocking Drugs: Indications
Main use: facilitating controlled ventilation during surgical procedures Endotracheal intubation (short-acting) To reduce muscle contraction in an area that needs surgery Diagnostic drugs for myasthenia gravis Other uses Copyright © 2017, Elsevier Inc. All rights reserved.

Contraindications Adverse effects Drug interactions Toxicity and management of overdose Antidotes: anticholinesterase drugs such as neostigmine, pyridostigmine, and edrophonium Copyright © 2017, Elsevier Inc. All rights reserved.

Neuromuscular Blocking Drugs: Safety
Respiratory muscle paralysis occurs with these drugs. Emergency ventilation equipment must be immediately available. Copyright © 2017, Elsevier Inc. All rights reserved.

Neuromuscular Blocking Drugs: Depolarizing Drugs
Succinylcholine Works similarly to neurotransmitter acetylcholine (ACh), causing depolarization Metabolism is slower than ACh, so as long as succinylcholine is present, repolarization cannot occur. Result: flaccid muscle paralysis Copyright © 2017, Elsevier Inc. All rights reserved.

Neuromuscular Blocking Drugs: Depolarizing Drugs (Cont.)
Pavulon Long-acting nondepolarizing NMBD Used as an adjunct to general anesthesia to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation Most commonly used for long surgical procedures that require prolonged muscle paralysis Works similarly to the neurotransmitter ACh, causing depolarization Copyright © 2017, Elsevier Inc. All rights reserved.

Neuromuscular Blocking Drugs: Depolarizing Drugs (Cont.)
Vecuronium (Norcuron) Intermediate-acting nondepolarizing NMBD Used as an adjunct to general anesthesia to facilitate tracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation Long-term use in the ICU setting has resulted in prolonged paralysis and subsequent difficulty weaning from mechanical ventilation Copyright © 2017, Elsevier Inc. All rights reserved.

A patient is to receive a NMBD while on mechanical ventilation. While the patient is receiving this medication, the nurse should expect the patient to be sedated. resisting the ventilator. awake but unable to move. pain free. Correct answer: C Rationale: NMBDs make the patient unable to move, but they do not cause sedation or relieve pain. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

Nursing Implications Always assess past history of surgeries and response to anesthesia. Assess past history, allergies, and medications. Assess use of alcohol, illicit drugs, and opioids. Copyright © 2017, Elsevier Inc. All rights reserved.

Nursing Implications (Cont.)
Assessment is vital during preoperative, intraoperative, and postoperative phases Vital signs Baseline lab work, ECG Oxygen saturation ABCs (airway, breathing, circulation) Monitor all body systems Copyright © 2017, Elsevier Inc. All rights reserved.

Each perioperative phase has its own complex and very specific nursing actions. Provide preoperative teaching about the surgical procedure and anesthesia. Copyright © 2017, Elsevier Inc. All rights reserved.

Perform close and frequent observation of the patient and all body systems. During a procedure, monitor vital signs and ABCs. Watch for sudden elevations in body temperature, which may indicate malignant hyperthermia. Copyright © 2017, Elsevier Inc. All rights reserved.

A patient in the ICU will be receiving an NMBD. Which piece of equipment is essential to have nearby when the nurse initiates this therapy? Defibrillator Sphygmomanometer Mechanical ventilator Oxygen source Correct answer: C Rationale: NMBDs paralyze the respiratory muscles; it is essential to have sufficient ventilator support nearby in case the medication causes the patient to lose the ability to breathe. Oxygen alone is not sufficient. Copyright © 2017, Elsevier Inc. All rights reserved. Elsevier items and derived items © 2009, 2005, 2001 by Saunders, an imprint of Elsevier Inc.

During recovery, monitor for cardiovascular depression, respiratory depression, and complications of anesthesia. Implement safety measures during recovery, especially if motor or sensory loss occurs because of local anesthesia. Copyright © 2017, Elsevier Inc. All rights reserved.

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