General & Local Anesthetics Revised

Causes complete loss of consciousness and loss of body reflexes, including paralysis of respiratory muscles

General anesthesia

Anesthesia that numbs a large area of the body

Regional anesthesia

Numbs a small, specific area; no paralysis of respiratory function

Local anesthesia

Local anesthesia can cause respiratory depression. True or false?

False

Monitored anesthesia care (MAC)

Use of local anesthesia along with sedation and analgesia

• 1st step

• Safe administration of anesthesia; airway is secured

  • Anesthesia is administered to patient typically via IV or inhaled agents

  • Smoothly transition patient from awake state to unconsciousness

  • Airway is secured via endotracheal tube or nasopharyngeal mask

  • Vital signs stabilized

Induction

• 2nd step

• Maintain patient safety and unconsciousness during procedure

  • Patient is kept at an adequate depth of anesthesia for duration of surgical procedure

  • Provider will continue to monitor and adjust depth of anesthesia

  • Adjunct drugs, opioids, NMBDs are used

Maintenance phase

Anesthesia phase where adjunct drugs, opioids, and NMBDs are used

Maintenance phase

Anesthesia phase where airway is secured and vital signs stabilized

Induction phase

• 3rd, final phase

• Anesthetic agents are decreased or discontinued to allow patient to gradually regain consciousness

Emergence phase

Use of volatile liquids or gases that are vaporized in oxygen and inhaled

Inhalational anesthetics

Anesthetics that are administered IV

Parenteral anesthetics

Drugs that enhance clinical therapy when used simultaneously with another drug

Adjunct anesthetics

Examples of adjunct drugs

• Opioids for pain control

• Benzodiazepines for anxiety and amnesia

• NMBDs for muscular relaxation

Prodrug of inhaled volatile liquids (IVLs)

Desflurane (Forane)

Common suffix for IVLs

-flurane

MOA of IVLs

• Enhance GABA activity

• Inhibit NMDA receptors (reduces excitatory signaling)

IVLs indication

Induction and maintenance of general anesthesia; has rapid onset & elimination

PONV and malignant hyperthermia

Adverse effects of IVL

GABA

Primary inhibitory neurotransmitter in the CNS. Increasing GABA activity promotes sedation and anesthesia

IVLs such as desflurane have rapid onset and rapid elimination. True or false?

True

Malignant hypethermia

Life threatening emergency that occurs during or/after administration of IVL general anesthesia or NMBDs like succinylcholine

• Symptoms include sudden elevation in body temp (>104° F), tachypnea, tachycardia, muscle rigidity

• Initial symptoms are sudden tachycardia, tachypnea, muscle rigidity

What must be done for patient who has hx of malignant hyperthermia?

Patient needs TIVA

Prodrug of inhaled gas

Nitrous oxide (laughing gas)

MOA of inhaled gases

NMDA receptor antagonist

• PONV in operations that require use for more than 1 hour

• Monitor for signs of hypoxia

Adverse effects of inhaled gases

Parenteral agents

Nonbarbiturate hypnotics, Dissociative Anesthetics, Alpha2-Adrenergic Agonist

Prodrug of nonbarbiturate hypnotics

Propofol (Diprivan)

MOA of nonbarbiturate hypnotics

Depresses CNS by enhancing GABA activity

Inhaled gases indication

Adjunct to other anesthetics; procedural sedation (rapid onset & recovery)

Nonbarbiturate hypnotics indication

Induction and maintenance of anesthesia; sedation

Nonbarbiturate hypnotics contraindications

• Egg or soy allergy

• Lipid metabolism disorders

Hypotension & respiratory depression

Adverse effects of nonbarbiturate hypnotics (propofol)

Nursing considerations for nonbarbiturate hypnotics (propofol)

• Monitor VS closely

• Use aseptic technique when handling; risk for bacterial contamination with IV use

• Be aware of state regulations regarding nurse administration of propofol

Prodrug of Dissociative Anesthetics

Ketamine (Ketalar)

MOA of dissociative anesthetics

Binds to receptors in both the CNS and PNS, including opioid receptors and NMDA receptors

Dissociative anesthetics (ketamine) indication

• General anesthesia and moderate sedation

• Often used in the ED

• Major depression refractory to other treatment (if patient is resistant to antidepressants)

• Psychometric effects (hallucinations, nightmares, emergence delirium)

• Tachycardia and HTN (useful in emergencies; bad in those with heart disease)

• Increased salivation, N/V

Adverse effects of dissociative anesthetics (ketamine)

What anesthetic may need to be administered with benzodiazepines?

Ketamine

What anesthetic can be given IM or Sub-Q?

Ketamine

Nursing considerations for dissociative anesthetics (ketamine)

• Can be given IV, IM, or subQ

• May need administration with benzodiazepines (anxiety relief)

Prodrug of Alpha2-Adrenergic Agonists

Dexmedetomidine (Precedex) 

MOA of Alpha2-Adrenergic Agonists

Stimulate alpha₂-adrenergic receptors in the CNS and PNS → Reduces norepinephrine release, which decreases SNS activity

Alpha2-Adrenergic Agonists (dexmedetomidine) indication

• Procedural sedation, surgeries of short duration

• Sedation of mechanically ventilated patients in the ICU

• Treat ETOH withdrawal

• Hypotension

• Bradycardia

• Nausea

Adverse affects of alpha2-Adrenergic Agonists (dexmedetomidine)

Infusions of this drug greater than 24 hrs associated with tolerance and dose-related adverse effect (withdrawal & rebound hypertension)

Dexmedetomidine

Nursing implications for alpha2-Adrenergic Agonists (dexmedetomidine)

• Infusions greater than 24 hrs associated with tolerance and dose-related adverse effects (rebound hypertension and withdrawal)

• Double check dosage calculations

  • Dosed in mcg/kg/hr

Drug dosed in mcg/kg/hr

Dexmedetomidine

Sites primarily affected by adverse effects of general anesthetics

Heart, liver, kidney, respiratory tract, peripheral circulation

Myocardial depression is commonly seen in 

Use of general anesthetics 

Overdose of general anesthetics can lead to

Cardiac and respiratory arrest; ultimate causes of death in an overdose

General anesthetics drug interactions

• Antihypertensives: increased hypotensive effects

• Beta blockers: increased myocardial depression

Nursing implications of general anesthetics before operation

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

• Assess past medical history, allergies, and medications.

• Assess use of alcohol, illicit drugs, and opioids

Assessment during preoperative, intraoperative, and postoperative phases

• Vital signs

• Baseline lab work

• ECG 

• ABCs (airway, breathing, circulation)

• Monitor all body systems

Moderate Sedation AKA

Conscious sedation or procedural sedation

Does not cause complete loss of consciousness

• Preserves the patient’s ability to maintain own airway and to respond to verbal commands

Moderate sedation

Name the general anesthetics

IVLs, inhaled gasses, parenteral anesthetics, adjunct anesthetics

Used for diagnostic procedures and minor surgical procedures that do not require deep anesthesia

Moderate sedation

Procedure that has rapid recovery time and greater safety profile than general anesthesia

Moderate sedation

Moderate sedation is a combination of an _________  or  _______ and an __________

IV benzodiazepine (midazolam); propofol; opiate analgesic (fentanyl or morphine)

Used to render a specific portion of the body insensitive to pain; does not cause loss of consciousness

Local anesthetic

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

Types of local anesthetic

• Central: spinal, intrathecal, epidural

• Peripheral: infiltration, nerve block, topical

Prodrug of local anesthetics

Lidocaine

MOA of local anesthetics

• Inhibits conduction of nerve impulses from sensory nerves

• Blocks sodium channels in nerve cells, preventing pain signal transmission

Lidocaine indication

• Infiltration (Injection into tissue; for suture/small incisions)

• Nerve block (injection into nerve → regional anesthesia; dental surgeries)

• Topical

Adverse effects of lidocaine

Minimal and usually limited

When does LAST occurs 

Happens when large doses are absorbed into systemic circulation; remove lidocaine patches after 12 hours 

Why combine a local anesthetic with epinephrine?

Epinephrine constricts the blood vessels and restricts the effect to a local area; prevent LAST

Numbness of the tongue/mouth, metallic taste, tinnitus, visual disturbance, agitation, twitching, seizures; can escalate to CNS depression and cardiorespiratory arrest

S&S of LAST

Treatment for LAST

Supportive care, lipid emulsion therapy 

NMBD MOA

Prevent nerve transmission in skeletal and smooth muscle, resulting in muscle paralysis

NMBD interaction with respiratory system

Paralyze the skeletal muscles required for breathing: the intercostal muscles and the diaphragm

NMBD indication

• Facilitating controlled ventilation during surgical procedures

• Endotracheal intubation (short acting)

• Reduce muscle contraction in an area that needs surgery

• Diagnostic drugs for myasthenia gravis

Diagnostic drugs for myasthenia gravis

NMBDs

Drug used to install endotracheal tubing

NMBDs

Supportive treatment for LAST entails

• Recognize S&S

• Secure ABCs

• Stop local anesthetic exposure immediately 

• Treat seizures

• Administer lipid emulsion therapy

Prodrug of depolarizing NMBDs

Succinylcholine (Anectine, Quelicin)

MOA of depolarizing NMBDs

NMBD structure similar to ACh; stimulates ACh receptors, causing initial muscle contraction. Slower metabolism leads to prolonged depolarization and flaccid paralysis

• muscle partially contracted but can’t move

Depolarizing NMBD indication

Facilitate ET intubation 

• Muscular fasciculations (twitching) if used for long periods of time

• BBW: Sudden cardiac arrest

Adverse effects of depolarizing NMBDs (succinocyholine)

BBW for succinocyholine and other depolarizing NMBDs

Sudden cardiac arrest

Nursing implications for depolarizing NMBDs

• Administer in settings equipped for airway management

• Respiratory muscle paralysis occurs with these drugs.

• Emergency ventilation equipment must be immediately available.

• Can trigger malignant hyperthermia

Malignant hyperthermia can be caused by

NMBDs such as succinocyholine and IVLs (-fluranes)

Prodrug of nondepolarizing NMBDs

Rocuronium (Zemuron)

Name the nondepolarizing NMBDs

Rocuronium (Zemuron) & vecuronium (Norcuron)

MOA of nondepolarizing NMBDs

Binds and blocks ACh receptors; inhibits stimulation of muscle fibers and skeletal muscle contraction; longer acting

How does the MOA of depolarizing and nondepolarizing NMBDs differ?

Shorter acting; depolarizing NMBDs stimulate ACh receptors resulting in partial contraction; nondepolarizing NMBDs block ACh receptors leading to paralysis

Nondepolarizing NMBDs indication

• Is rapid-to-intermediate acting

• Adjunct to general anesthesia

• For longer surgeries

Respiratory muscle paralysis occurs with these drugs.

General anesthetics; NMBDs

Nursing implications for nondepolarizing NMBDs

• Administer in settings equipped for airway management

• Respiratory muscle paralysis occurs with these drugs

• Emergency ventilation equipment must be immediately available

• Antidote for reversing toxicity are anticholinesterase drugs

Anticholinesterase drugs

Antidote for nondepolarizing NMBDs; neostigmine, pyridostigmine, and edrophonium

Local anesthetics are TINS

Topical, infiltration, nerve block, and spinal

General anesthetics assessment

Always assess histories, V/S & all body systems prior to surgery & V/S & body systems during & after

Infusions of dexmedetomidine for >24 hours is associated with

Tolerance and dose-related adverse effects (withdrawal/rebound HTN)

Treating PONV

Administer prophylactic antiemetics

Treatment of malignant hyperthermia

Treat with cardiorespiratory support, body cooling, and dantrolene

Drug used to treat malignant hyperthermia

Dantrolene

Inhaled gases such as nitrous oxide are considered the weakest anesthetics. True or false?

True

Drugs that put patient in state of dissociation (patients appear awake with eyes open but are disconnected from their environment and do not perceive pain in the usual way)

Dissociative anesthetics (ketamine)