Pharmacology Chapter 11- General and Local Anesthetics

Summary of effects of anesthetics

*CV*- hypotension, tachycardia. *Respiratory* depression. *Cerebral vascular*- increased intracranial pressure. *GI*- decrease in hepatic blood flow -> decreased hepatic clearance. *Renal*- decreased glomerular filtration. *Skeletal*- muscle relaxation. *Cutaneous circulation*- vasodilation. *CNS* depression: nystagmus, decreased alertness, decreased or loss of consciousness, blurred vision.

Contraindications, Toxicity, and Interactions with General anesthesia

*Contraindications*- pregnancy, history of malignant hyperthermia, narrow angle glaucoma. *Interactions*- antihypertensives. *Toxicity and overdose*- respiratory arrest.

Peripheral Parenteral Anesthetics

*Infiltration* - Small amounts of drug are injected into a very small area. *Nerve Block* - Anesthetic is injected at a site where a nerve innervates a specific area.

General anesthesia

*Overall effect*: progressive reduction of sensory, motor, and CNS function. Initially produces loss of sense of sight, touch, taste, smell, and hearing. Cardiac and pulmonary are the last to be affected. *Indications and goals of anesthetics*- relax smooth muscles and produce unconsciousness.

Summary of Indications for use of Local anesthetics

*Surgical*- when general anesthetics are a big risk, require lighter anesthesia, dental and diagnostic procedures. *Management of chronic pain*- cancer pain, back pain, post-operatively, orthopedic pain. *Spinal*- childbirth.

Indications for use of Neuromuscular blocking drugs (NMBDs)

- Maintain controlled ventilation during surgery. - Endotracheal intubation. - To reduce muscle contraction/movement during surgery.

Conditions that can increase the risk of toxic effects of Neuromuscular blocking drugs (NMBDs)

- Malignant hyperthermia. - Hypocalcemia. - Hypokalemia. - Hypothermia. - Acidosis. - Myasthenia gravis. - Paraplegia.

The nurse is administering an NMBD to a patient during a surgical procedure. Number the following phases of muscle paralysis in the order in which the patient will experience them. (Number 1 is the first step) A. Paralysis of intercostals and diaphragm muscles. B. Muscle weakness C. Paralysis of muscles of the limbs, neck, and trunk. D. Paralysis of small rapidly moving muscles (fingers, eye)

1. B. Muscle weakness 2. D. Paralysis of small rapidly moving muscles (fingers, eye) 3. C. Paralysis of muscles of the limbs, neck, and trunk. 4. A. Paralysis of intercostals and diaphragm muscles.

Infiltration anesthesia is often given with-

A vasoconstrictor (epinephrine). Helps confine anesthesia to the injected area. Prevents systemic absorption of the drug (decreases chances of cardiovascular and respiratory compromise). Decreases blood loss.

The surgical nurse is reviewing operative cases scheduled for the day. Which of these patients is more prone to complications from general anesthesia? A. A 79-year-old woman who is about to have hip replacement surgery. B. A 49-year-old male athlete who quit heavy smoking 12 years ago. C. A 30-year-old woman who is in perfect health but has never had anesthesia. D. A 50-year-old woman scheduled for outpatient laser surgery for vision correction.

A. A 79-year-old woman who is about to have hip replacement surgery.

A patient is recovering from general anesthesia. What is the nurse's main concern during immediate postoperative period? A. Airway B. Pupillary reflexes C. Return of sensations D. Level of consciousness

A. Airway

When preparing for an application of a local topical anesthetic, which of the following would be most important? A. Assess skin integrity. B. Assess reflexes in that area. C. Determine current muscle tone. D. Assess respiratory function.

A. Assess skin integrity.

Which of the following drugs is used for moderate sedation and is not a barbiturate? A. Midazolam B. Nitrous oxide C. Thiopental D. Halothane

A. Midazolam

The nurse monitoring a patient after surgery keeps in mind that the primary concern with use of a neuromuscular blocking drug is which adverse effect? A. Respiratory arrest B. Headache C. Bradycardia D. Hypertension

A. Respiratory arrest

Which drug classes are used as adjunctive drugs with anesthesia? (Select all that apply) A. Sedative-hypnotics B. Anticonvulsants C. Anticholinergics D. Inhaled gas E. Opioid analgesics

A. Sedative-hypnotics C. Anticholinergics E. Opioid analgesics

Moderate sedation

AKA conscious sedation or procedural sedation. Involves a *combination of an IV benzodiazepine and an opioid analgesic*. Usually Midazolam and Morphine. Anxiety and sensitivity to pain is reduced. Patient cannot remember the procedure. Preserves the patient's airway, and patients can follow verbal commands. Used for diagnostic procedures. Rapid recovery time.

Local anesthetics

AKA regional anesthetics. Renders a specific portion of the body insensitive to pain. Interferes with nerve impulse transmission to a specific area of the body. Do not cause a loss of consciousness. *Types*: Topical, Parenteral: Central (spinal) and Peripheral (infiltration, nerve block).

Non-depolarizing Neuromuscular blocking drugs (NMBDs)

Acetylcholine antagonist. Prevents acetylcholine from acting at neuromuscular junction, so muscle cells are not stimulated. Example: *Rocuronium*- used in surgery for muscle relaxation and mechanical ventilation.

Adverse effects of local anesthetics

Adverse effects mostly occur with parenteral, if: - inadvertent intravascular Injection occurs. - excessive dose given. - fast rate of administration. - slow metabolic breakdown. - injected into highly vascular tissue. *Adverse effects*- spinal headache, severe hypotension, depressed circulatory and respiratory function.

Topical Local Anesthetics

Applied directly to skin or mucous membranes. Usually have very few side effects. Available as: creams, solutions, gels, ophthalmic drops, sprays. *Examples*- - Benzocaine (Dermoplast) - Cocaine - Lidocaine (Lidoderm)

Which of the following conditions would predispose a patient to experience a prolonged action of succinylcholine? A. Renal failure B. Hypokalemia C. Heart disease D. Inflammatory bowel disease

B. Hypokalemia

Which of the following is an identified advantage for the use of nitrous oxide? A. It demonstrates effectiveness as a single agent. B. It has good analgesic properties. C. It does not promote postoperative nausea and vomiting. D. It offers a parenteral and inhaled route option.

B. It has good analgesic properties.

To decrease the possibility of a headache after spinal anesthesia, the nurse will provide which instruction to the patient? A. Sit in high Fowler's position B. Maintain strict bedrest C. Limit fluids. D. Ambulance in the hall several times a day.

B. Maintain strict bedrest

When the effects of local anesthetics begin to wear off, which physiologic response is the first to occur? A. Memory returns B. Motor activity returns C. Sensory activity returns D. Autonomic activity returns

B. Motor activity returns

The nurse is reviewing a policy for local anesthesia. Local anesthesia is indicated for which procedure(s)? (Select all that apply) A. Cardioversions B. Suturing a skin laceration C. Diagnostic procedures D. Long-duration surgery E. Dental procedures

B. Suturing a skin laceration C. Diagnostic procedures E. Dental procedures

During a patient's recovery from a lengthy surgery, the nurse monitors for signs of malignant hyperthermia. In addition to a rapid rise in body temperature, which assessment finding would indicate the possible presence of this condition? (Select all that apply) A. Respiratory depression B. Tachypnea C. Tachycardia D. Seizure activity E. Muscle rigidity

B. Tachypnea C. Tachycardia E. Muscle rigidity

A patient is about to undergo cardioversion, and the nurse is reviewing the procedure and explaining moderate sedation with propofol. The patient asks, "I am afraid of feeling it when they shock me." What is the nurse's best response? A. "You won't receive enough of a shock to feel anything." B. "You will feel the shock but you won't remember any of the pain." C. "These medications will help ease any pain during the procedure, and many patients often report having no recollection of the procedure." D. "They will give you enough pain medication to prevent you from feeling it."

C. "These medications will help ease any pain during the procedure, and many patients often report having no recollection of the procedure."

Which of the following is associated with a bizarre state of unconsciousness in which the patient appears to be awake and yet cannot feel pain? A. Propofol B. Midazolam C. Ketamine D. Etomidate

C. Ketamine

A patient who has just returned from surgery has suddenly developed a severe elevation in body temperature. The nurse recognizes this change may indicate which condition? A. A normal temperature change after surgery. B. Malignant hypertension C. Malignant hyperthermia D. Fever

C. Malignant hyperthermia

Nursing implications for NMBDs

Can increase intracranial pressure, so watch for history of head injury or glaucoma. Imbalance of potassium and calcium can lead to neuromuscular toxicity. Patients still need anesthesia for pain and anxiety control, sedation.

Adjunctive anesthesia

Creates "balanced anesthesia." Used to decrease anxiety, induce amnesia, sedate, and provide pain control. *Opioids:* fentanyl, morphine. *Benzodiazepines*: midazolam (Versed). *Anticholinergics*: atropine. *Antihistamine*: hydroxyzine (Vistaril). *Neuromuscular blocking drugs*.

During recovery from general anesthesia, which of the following would be a priority? A. Monitoring return of reflexes. B. Providing comfort measures. C. Providing pain relief. D. Having emergency respiratory equipment available.

D. Having emergency respiratory equipment available.

During a procedure, the nurse is monitoring a patient who has received dexmedetomidine (Precedex) for moderate sedation. The nurse will observe for which potential adverse effect? A. Respiratory depression B. Tachycardia C. Dizziness D. Hypotension

D. Hypotension

Which nursing diagnosis is possible for a patient who is now recovering after having been under general anesthesia for 3 to 4 hours during surgery? A. Impaired urinary elimination r/t the use of vasopressors as anesthetics. B. Increased cardiac output r/t the effects of general anesthesia. C. Risk for falls r/t decreased sensorium for 2 to 4 days postoperatively. D. Impaired gas exchange d/t the CNS depressant effect of general anesthesia.

D. Impaired gas exchange d/t the CNS depressant effect of general anesthesia.

The physician has requested "lidocaine with epinephrine." The nurse recognizes that the most important reason for adding epinephrine is that it- A. Helps to calm the patient before the procedure. B. Minimizes the risk for an allergic reaction. C. Enhances the effect of the local lidocaine. D. Reduces bleeding in the surgical area.

D. Reduces bleeding in the surgical area.

After a patient receives succinylcholine, the nurse would assess the patient for which of the following initially? A. Muscle pain. B. Hyperthermia. C. Hypotension. D. Respiratory depression.

D. Respiratory depression.

Balanced anesthesia

General anesthetic + adjunct. Combination of drugs used to achieve what a single drug can't. Enhances general anesthetic so we can use less.

Nursing implications for General anesthetics

Get baseline VS. Airway, breathing, circulation (ABCs). Baseline mental status/swallowing ability. Past history of response to general anesthesia. Assess medication history (esp. antihypertensives). Assess drug and alcohol use. History of smoking. History of malignant hyperthermia. Know signs and symptoms of malignant hyperthermia: tachycardia, diaphoresis, muscle rigidity, tachypnea, hyperthermia. Check the following labs: CBC, renal and liver function.

Prevention + Treatment of spinal headache

Hydrate. Lie flat for 24-48 hours. Blood patch.

Inhaled General Anesthetics

Inhaled gas- *can't achieve full anesthesia, never used as the #1 anesthetic*, except in dental cases and surgery needing "light anesthesia." Nitrous oxide: inhaled gas. Inhaled volatile liquids: vaporized in O2 and inhaled. - Desflurane (Suprane) - Sevoflurane (Ultrane)

Parenteral Local Anesthetics

Injected IV or into the CNS by various spinal injections. Central or Peripheral

Infiltration Anesthesia

Injection is given across the path of nerves in a specific area. Can be intradermal, subQ, submucosal. May be given in tissues around the operative site. Used for minor surgical and dental procedures.

Examples of Local Parenteral Drugs

Lidocaine (Xylocaine) Mepivacaine (Carbocaine) Procaine (Novocain)

Action of General Anesthetics- Overton Meyer Theory

Potency of anesthetics vary with lipid solubility. Fat soluble drugs are more potent. Nerve cell membranes have a high lipid content. Lipid soluble drugs can cross the blood brain barrier to produce CNS depression.

Malignant hyperthermia

Potentially fatal reaction to some anesthetics. *Symptoms*- hyperthermia, hypertension, tachycardia, tachypnea, diaphoresis, muscle rigidity.

Neuromuscular blocking drugs (NMBDs)

Prevent nerve transmission in skeletal and smooth muscles, resulting in paralysis. Drugs paralyze respiratory muscles, so artificial respiration/mechanical ventilation is required. Patients can not breathe on their own. Do *not* cause sedation or pain relief. Two types: depolarizing and non-depolarizing.

Safety with NMBDs

Respiratory muscles are paralyzed. Emergency ventilation equipment needs to be near by! Must have adequate anesthesia (pain control + sedation). Overdose can happen: prolonged paralysis that requires prolonged ventilation, cardiovascular collapse.

Central Parenteral Local Anesthetics

Spinal or Neuraxial- block all peripheral nerves that branch out distal to injection site. - *Intrathecal*- injected into subarachnoid space. Used for abdominal surgery, or with patients who cannot have general anesthesia. - *Epidural*- injected into the epidural space, but do not puncture dura mater. Used for labor delivery, and post op pain.

Nerve Block Anesthesia

Used for surgical, dental, therapeutic management of pain, and diagnostic procedures Can give a large amount of drug without it affecting the entire body. Provides very localized, specific pain control.

Parenteral General Anesthetics

Used to induce or maintain general anesthesia or loss of consciousness. Used to induce amnesia. Used with inhaled anesthetics. Examples- - Etomidate (Amidate) - *Ketamine (Ketalar)*- dissociative drug. Used for moderate sedation and painful procedures. - *Propofol (Diprivan)*- rapid onset, short duration. Used for moderate sedation and with ventilated patients. - Thiopental (Pentothal)

Depolarizing Neuromuscular blocking drugs (NMBDs)

Works similarly to acetylcholine, causing depolarization. Results in muscle paralysis. Example: *Succinylcholine*- very short acting. Used for endotracheal intubation. Malignant hyperthermia is a big risk.