Study Notes on Anesthetics

Overview of Anesthetics

  • Anesthetics are drugs that reduce or eliminate pain by depressing nerve function in the central nervous system (CNS) and peripheral nervous system.

Types of Anesthesia

  • 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 tissues innervated by anesthetized nerves.

  • Monitored Anesthesia Care (MAC):

    • Combines local anesthesia with sedation and analgesia.

Administration and Providers

  • Administered by:

    • Anesthesiologist

    • Nurse Anesthetist (CRNA)

    • Anesthesia Assistant

Mechanisms and Effects of General Anesthetics

  • Goals:

    • Induce varying degrees of:

    • Pain relief

    • Depression of consciousness

    • Skeletal muscle relaxation

    • Reflex reduction

  • Mechanism of Action:

    • Causes orderly reduction of sensory and motor functions in the CNS leading to unconsciousness and relaxation of smooth muscles.

Types of General Anesthetics

  • Inhalational Anesthetics:

    • Volatile liquids or gases vaporized in oxygen and inhaled.

  • Parenteral Anesthetics:

    • Administered intravenously.

  • Adjunct Anesthetics:

    • Drugs that enhance clinical therapy when used alongside other anesthetics.

Indications for Use

  • Procedures requiring unconsciousness, muscular relaxation, or visceral smooth muscle relaxation.

  • Also used in electroconvulsive therapy for depression.

Contraindications

  • Known Drug Allergy

  • Conditions that affect the use of anesthetics:

    • Pregnancy

    • Narrow-angle glaucoma

    • Acute porphyria

    • History of malignant hyperthermia

Adverse Effects

  • Vary based on dosage and drug used; common sites affected include:

    • Heart

    • Peripheral circulation

    • Liver

    • Kidneys

    • Respiratory tract

Specific Risks

  • Malignant Hyperthermia:

    • Triggered during or after inhaled general anesthesia or neuromuscular blockers.

    • Symptoms: Sudden body temperature elevation (>104°F), tachypnea, tachycardia, muscle rigidity.

    • Treated as an emergency with supportive care and dantrolene.

  • Toxicity Management:

    • Life-threatening in overdose; can cause cardiac and respiratory arrest.

    • Anesthesia must be administered in a controlled environment.

Drug Interactions

  • Antihypertensives: May intensify hypotensive effects.

  • Beta blockers: Increased myocardial depression.

Moderate Sedation

  • Called conscious sedation.

  • Does not cause complete loss of consciousness; does not typically induce respiratory arrest.

  • Combination of an IV benzodiazepine (e.g., midazolam) with an opioid analgesic (e.g., fentanyl).

  • Patient retains airway and responsiveness; should have rapid recovery.

Indications

  • Used for diagnostic and minor surgical procedures requiring sedation without deep anesthesia.

Nursing Considerations

  • Important to assess past history of surgeries and anesthesia response.

  • Monitor vital signs and perform baseline lab work, ECG, and assess for airway and respiratory function throughout perioperative phases.

Local Anesthetics

  • Render a specific part of the body insensitive to pain without losing consciousness.

Types

  • Topical: Applied directly (creams, ointments).

  • Parenteral: Injected into the body (spinal injections, nerve blocks).

Common Local Anesthetics

  • Lidocaine, Bupivacaine, Chloroprocaine, Mepivacaine, Procaine, Ropivacaine.

Indications for Use of Local Anesthetics

  • Surgical, dental, and diagnostic procedures.

  • Treating chronic pain, particularly during childbirth or minor surgeries.

Adverse Effects

  • Limited but may occur with improper administration; most risks arise from inadvertent intravascular injection or excessive doses.

  • Severe headaches can occur following spinal anesthesia (treatment: bed rest, analgesics, caffeine).

Nursing Implications

  • Continuous patient observation and assessment for all bodily systems during diagnosis and procedures.

  • Monitor for signs of malignant hyperthermia, cardiovascular, and respiratory depression.

  • Teach patients about post-operative care, including turning, coughing, and deep breathing exercises.

Conclusion

  • Comprehensive understanding of anesthetics, their effects, indications, and nursing implications is crucial for safe patient care throughout all stages of a surgical procedure.