Module 2 Drugs That Support Anesthesia

What is a local anesthetic's mechanism of action?

Blocks Na⁺ channels → prevents depolarization/action potential → loss of sensation (no loss of consciousness)

What is the prototype local anesthetic and its class?

Lidocaine (an amide); common esters: procaine, benzocaine

When are local anesthetics used?

Topical (burns, suturing), mucosal (dental/nasal), infiltration/nerve block, epidural/spinal for labor/lower abdominal surgery

What agents are involved in balanced anesthesia?

Preoperative Medications, Sedative-Hypnotics, Antiemetics, Antihistamines, Opioids

What are systemic adverse effects of local anesthetics?

CNS stimulation (restlessness, tremor, confusion, seizures) → may progress to CNS depression/respiratory depression; hypotension with spinal

Why is epinephrine added to lidocaine?

to act as a vasoconstrictor which slows absorption of the lidocaine into the bloodstream, prolonging the duration of numbing effect and reducing risk of anesthetic toxicity

What are key local-anesthetic nursing interventions?

Monitor VS during/after; watch for restlessness/tremors/paresthesias; for spinal hypotension: lower HOB, have ephedrine/phenylephrine available

What local-anesthetic admin safety should I know?

Avoid eyes/broken skin; use correct concentration/form; some vials have preservatives (procedure-specific contraindications)

What are lidocaine contraindications/precautions?

Allergy to amide anesthetics; viscous lidocaine contra <3 years; bradycardia/heart block → risk cardiac arrest at high doses

What drugs interact with lidocaine?

↑ levels: β-blockers, cimetidine, quinidine; phenytoin ↑ cardiac effects; procainamide + lidocaine ↑ CNS/cardiac effects

ATI check: Why is epi used with spinal lidocaine?

Prolongs anesthetic effects (answer C)

What is "balanced anesthesia"?

Use multiple drugs (sedative, opioid, IV induction, inhaled agent, antiemetic, ± NMJ blocker) to optimize anesthesia & minimize toxicity

What is moderate (conscious) sedation?

Depressed consciousness, amnesia, spontaneous ventilation, response to verbal stimuli; often midazolam + fentanyl; continuous monitoring

What adverse effects are common with general anesthetics?

Hypotension, respiratory depression/apnea, PONV, hypothermia, emergence agitation; rare malignant hyperthermia

What are early signs of malignant hyperthermia (MH)?

Rapid ↑ ETCO₂, masseter rigidity, tachycardia, acidosis, hyperkalemia; fever is late; treat with IV dantrolene + 100% O₂ + cooling

What barbiturate is used for induction?

Methohexital (IV): rapid induction/hypnosis for brief procedures; adjunct to longer cases

What is methohexital used for?

Prototype short-acting barbiturate: induces anesthesia/hypnosis for brief procedures; adjunct anesthesia for >15 min cases.

What is phenobarbital used for?

Prototype long-acting barbiturate: prevention of generalized tonic-clonic & febrile seizures (rarely as a sedative now)

What barbiturate nursing implications matter most?

Continuous VS/airway monitoring; slow IV; have resuscitation ready; avoid extravasation; caution hepatic/renal disease; additive CNS depressants

How are barbiturate overdoses managed?

Supportive care: airway/ventilation, O₂, fluids/pressors; consider urine alkalinization; high suicide/resp arrest risk

Which benzodiazepine is the anesthesia prototype?

Midazolam (also diazepam)

What are the pharmacological actions of benzodiazepines?

They are CNS depressants. They enhance the inhibitory effects of the transmitter gamma-aminobutyric acid, abbreviated GABA.

What are the main indications for benzodiazepines in periop & clinical care?

Sedation Sleep induction Skeletal muscle relaxation Anxiety relief Anxiety-related depression Treatment of acute seizure disorders Treatment of alcohol withdrawal Agitation relief Balanced anesthesia Moderate or conscious sedation

What are the contraindications/precautions for benzodiazepines?

Allergy, narrow-angle glaucoma, pregnancy; use caution with psychosis or acute alcohol intoxication and in cardiac/pulmonary/renal/neuromuscular disorders.

What is the mechanism that explains their sedative/anxiolytic effects?

They enhance GABA at benzo receptors → CNS depression (calming, amnesia, muscle relaxation) without REM suppression as profound as barbiturates.

What are the common adverse effects of barbiturates?

CNS depression (drowsiness, somnolence, ataxia), respiratory depression, vertigo, N/V/constipation, thrombocytopenia, agranulocytosis, ↓REM

What are common adverse effects of benzodiazepines?

Drowsiness/sedation, dizziness/vertigo, headache, cognitive impairment, hypotension, GI effects, urinary retention; fall risk in older adults; "hangover" daytime sleepiness.

What nursing interventions are critical for moderate (conscious) sedation with benzos

use slow IV bolus, wait ≥2 min before redosing; continuous monitoring (airway, SpO₂/ETCO₂, ECG, BP); have resuscitation equipment ready; expect amnesia and ensure escort after discharge

What patient education should be given before/after benzo sedation

Explain amnesia and drowsiness; no driving/decisions for 24 h; avoid alcohol/CNS depressants; report breathing trouble or severe dizziness; expect close vital-sign monitoring.

What is the benzodiazepine reversal agent?

Flumazenil (competitive benzodiazepine antagonist) for toxicity/oversedation.

Who should not receive periop benzos?

Pregnancy/lactation, benzo allergy, acute angle-closure glaucoma; caution cardiac/pulmonary/renal/neuromuscular disease

What opioid is used to support anesthesia?

Fentanyl (adjunct for analgesia, sedation; part of neuroleptanalgesia with droperidol + N₂O)

What are fentanyl adverse effects/interventions?

Sedation, N/V, respiratory depression, circulatory collapse → continuous VS/LOC; have naloxone and resus equipment available

What are fentanyl admin/teaching pearls?

Forms: IV, transmucosal lozenge (suck ≥15 min, no chewing); expect drowsiness, report nausea for antiemetic

Who should avoid or use caution with fentanyl?

Substance use history, obstetric deliveries (neonatal resp depression), teratogenic risk; caution ↑ICP, extremes of age, organ dysfunction

Which fentanyl interactions are key?

Other CNS depressants ↑ risk; MAOI within 14 days → hypertensive crisis—screen antidepressant use

What are neuromuscular blocking agents (NMBAs) used for?

Produce skeletal muscle paralysis (no sedation/analgesia) for intubation and surgery; mechanical ventilation required

Which NMBA types are common?

Depolarizing: succinylcholine; non-depolarizing: rocuronium, vecuronium, cisatracurium, pancuronium

What adverse effects/contraindications matter for NMBAs?

Apnea until reversed; succinylcholine: hyperkalemia, bradycardia, ↑ICP/IOP, MH trigger, myalgias; contra in MH hx; monitor for residual weakness

What are essential nursing considerations with paralytics?

Provide sedation & analgesia, ventilation, eye care, TOF monitoring, turn/skin/DVT precautions, clear labeling that patient is paralyzed, not unconscious; have reversal ready (e.g., neostigmine+glycopyrrolate or sugammadex)

What are barbiturates and why are they high-risk?

CNS depressants with a narrow therapeutic index; potentiate (make more effective) GABA → sedation/hypnosis/anesthesia/coma; narrow safe dose range