General Anesthetics

Exam #3

General Anesthetic

• Medication induced

• Reversible

• Unconsciousness

• Loss of protective reflex (ex: not able to cough/gag to prevent choking)

• Deeper than “deep sleep”

• Drug induced coma

• Arousal cannot occur

• Can be safely used after first trimester in pregnant women

Phases of Anesthesia

1. Induction (IV or inhaled)

2. Maintenance (adjunct medications)

3. Emergence (may reverse neuromuscular blocker)

Principles of Balanced Anesthesia

• Physiologic and pharmacologic equilibrium

• 4 elements

  • Amnesia (loss of memory)

  • Analgesia (absence of pain)

  • Hypnosis (unconsciousness)

  • Muscle relaxation or immobility

Prototype for General Anesthetic Agents (Inhaled)

Isoflurane

MOA of Isoflurane

Not clear

Use of Isoflurane

Induction (IV or inhaled) and maintenance of general anesthesia

Adverse Effects of Isoflurane

• Postoperative nausea and vomiting

• Malignant hyperthermia (high body temperature and severe muscle rigidity)

  • Treat with IV Dantrium

Contraindications for Isoflurane

• History of postoperative nausea and vomiting

  • Substitute TIVA (use IV instead of inhaled gas)

• Family history of malignant hyperthermia

Nursing Considerations for Isoflurane

Has an odor

What is Malignant Hyperthermia?

• Hypermetabolic response (body’s metabolism becomes extremely fast)

  • High temperature

  • Increased heart rate

  • Increased oxygen use

• Potentially fatal

What causes Malignant Hyperthermia?

• Inhalation anesthetic

• Succinylcholine (NMB)

• Linked to muscular disorders

How to Treat Malignant Hyperthermia?

• IV dantrolene sodium (Dantrium)

• Body cooling

Prototype for General Anesthetic Agents (IV)

Propofol

MOA of Propofol

Depresses CNS via GABA (neurotransmitter that slows down brain activity for relaxation) amplification (no analgesia)

Use of Propofol

Induction (IV or inhaled) and maintenance of general anesthesia

Adverse Effects of Propofol

• Pain

• Burning at IV site

Contraindications of Propofol

• Soy or egg allergy

• Lipid metabolism disorders (problem with how body processes fats)

Nursing Considerations of Propofol

• Risk of mishandling

• Aseptic technique (clean/sterile)

Second General Anesthetic (IV)

Ketamine

MOA for Ketamine

Produces analgesia without using opioid receptors

Use of Ketamine

Used in critically ill patients

• Maintains low blood pressure

• Maintains low heart rate

Adverse Effects of Ketamine

BBW:

• Emergence delirium (confusion, agitation, restlessness)

• Hallucinations

• Unpleasant dreams

Nursing Considerations for Ketamine

Monitor for recovery

Inhaled Anesthesia

• Risk of malignant hyperthermia

• Risk of hepatotoxicity

• Effects decrease after 30 minutes

• Higher chance of postoperative nausea and vomiting

• Odor may limit use

IV Anesthesia

• No risk of malignant hyperthermia

• Assess for food allergies

• Effects decrease quickly

• Postoperative nausea and vomiting less likely

• Aseptic technique

• Pain at IV site

Neuromuscular Blocking Agent

Muscle relaxant

Prototype for Neuromuscular Blocking (NMB) Agent

Vecuronium (non depolarizing)

MOA of Vecuronium

Suspends nerve impulses at the neuromuscular junction

Use of Vecuronium

Skeletal muscle paralysis for operations

• Intubation (tube in airway for breathing)

• Mechanical ventilation (machine helps or completely breathes for patient)

Adverse Effects of Vecuronium

Allergic reactions

• Mild urticaria (hives)

• Erythema (redness of skin)

Contraindications for Vecuronium

Known hypersensitivity

Nursing Considerations for Vecuronium

• Numerous interactions

• Recurarization monitoring

  • Return of weakness after assumed recovery

  • Difficulty swallowing

  • Weak cough

  • Trouble talking

Second NMB Agent

Succinylcholine (depolarizing)

MOA of Succinylcholine

The only depolarizing neuromuscular blocking agent

Use of Succinylcholine

Paralysis for tracheal intubation

• Rapid sequence intubation (RSI)

Adverse Effects of Succinylcholine

• BBW: Sudden cardiac arrest

• Can cause malignant hyperthermia

Contraindications of Succinylcholine

• History of malignant hyperthermia

• Preexisting hyperkalemia

Prototype for Benzodiazepine (BZD) (Adjuvant Medication)

Midazolam

MOA of Midazolam

Short acting IV medication

Use of Midazolam

Adjunct for all types of anesthesia

Adverse Effects of Midazolam

BBW: Profound respiratory depression

Nursing Considerations of Midazolam

• Oral syrup available for children

Reversal Agent for Midazolam

Flumazenil

Prototype for Opioid Anesthesia

Fentanyl

Use of Fentanyl

Supplement sedation and general anesthesia

Adverse Effects of Fentanyl

• Respiratory depression

• Nausea and vomiting

• Urinary retention

Reversal Drug for Fentanyl

Naloxone