Peri-Op (Test #4)

Anesthetic

•a substance that produces insensitivity to pain.

General Anesthesia (GA)

•a medication-induced reversable unconsciousness with loss of protective reflexes.

•Much deeper than sleep, more like a drug-induced coma

•Arousal, even to painful stimuli cannot occur

•Allows for surgery or other unpleasant therapeutic/diagnostic procedures

moderate (conscious) sedation

•Patient maintains protective airway reflexes

•Aroused with stimulation

•Procedures such as colonoscopy, biopsy

Types of Anesthesia: General

- Inhalation

- Intravenous

Types of Anesthesia: Moderate Sedation

- Conscious Sedation

- Monitored Anesthesia Care (MAC)

Types of Anesthesia: Neuromuscular Blocks

- Non-Depolarizing

- Depolarizing

Alpha2-adrenergic receptors

•Activated by catecholamines such as

Epinephrine & Norepinephrine

Why are pre-anesthetic medications given?

- reduce anxiety

- produce perioperative amnesia

- relieve preoperative and postoperative pain

Common pre-anesthetic medications

- Benzodiazepines

- Opioids

- Anticholinergic drugs

- Alpha2-Adrenergic Agonists

- Histamine 2 Blocker/PPI

Common Pre-anesthetic medication: Benzodiazepines (Drug Name)

IV midazolam [Versed]

Common Pre-anesthetic medication: Anticholinergic drugs (Drug Name)

Atropine

Common Pre-anesthetic medication: Alpha2-Adrenergic Agonists (Drug Name)

- clonidine and dexmedetomidine (Precedex)

Common Pre-anesthetic medication: Histamine 2 Blocker/PPI (Drug Name)

ranitidine (Zantac)

Why is ranitidine (Zantac) a common pre-anesthetic medication?

- reduce stomach acid and risk of aspiration

(it's a histamine 2 blocker/PPI)

Balanced Anesthesia: Inhalation - Amnesia: What is it? &

What medication causes this?

memory loss (limited duration of anesthesia)

- Benzodiazepines or inhalation anesthetics

Balanced Anesthesia: Inhalation - Analgesia: What is it? &

What medication causes this?

reduction/absence of pain

- Opioid or nonopioid medications

Balanced Anesthesia: Inhalation - Hypnosis: What is it? &

What medication causes this?

unconsciousness

- IV or inhalation anesthetics

Balanced Anesthesia: Inhalation - Muscle Relaxation or immobility

What medication causes this?

Neuromuscular blocking agents and/or inhalation anesthetics

General Anesthesia: Inhalation -Properties of an ideal Anesthetic

•Low tissue solubility and metabolism to reduce organ toxicity

•Chemical stability

Types of Anesthesia: Local

- Topical

- Injection (Infiltration/Regional)

Basic Pharmacology of Anesthetics

•Mechanism of Action (MOA) is via neurotransmitters

•Gamma-aminobutyric acid (GABA) receptors

•Acetylcholine (ACh) receptors

•Alpha2-adrenergic receptors

Acetylcholine (ACh) receptors

•Receptors that respond are called cholinergic receptors - there are 2 types...

•Muscarinic Cholinergic Receptors

•Nicotinic Cholinergic Receptors

•Drugs that affect "ACh" may be referred to as "Anticholinergics or Muscarinic Antagonist/Agonist"

Receptors that respond to Acetylcholine (ACh) receptors

"cholinergic receptors"

- Muscarinic Cholinergic Receptors

- Nicotinic Cholinergic Receptors

Common Pre-anesthetic medication: Opioids (Drug Name)

- morphine

- fentanyl

Balanced Anesthesia

•Use of several drugs to achieve a state of physiologic and pharmacologic equilibrium under general anesthesia

•4 elements work collectively to produce a superior outcome:

•Amnesia

•Analgesia

•Hypnosis

•Muscle relaxation or immobility

Who is General Anesthesia given by?

- licensed anesthesiologists (physicians)

- certified registered nurse anesthetists (CRNA)

What are the 3 phases of General Anesthesia?

1. Induction

2. Maintenance

3. Emergence

General Anesthesia: Inhalation Anesthetics

Volatile Liquids:

- *Isoflurane

- Desflurane

- Sevoflurane

Gases:

- *Nitrous oxide

- Oxygen

General Anesthesia: Inhalation MOA

•GABA (gamma-aminobutyrate)

•Loss of consciousness and amnesia

•Immobility or absence of response to noxious stimuli

General Anesthesia: Inhalation - Pharmacokinetics

Absorption & Distribution:

- lungs

- blood flow to brain

Metabolism:

- minimal (liver)

Elimination:

- Lungs

Isoflurane (Forane)

•Volatile Liquid

•High potency anesthetic

•Produces amnesia, skeletal muscle relaxation, and hypnosis

•Used for Induction and maintenance of general anesthesia

•Acts quickly/smoothly

•Can be adjusted easily

•Used alone or combo of other drugs - balanced anesthesia

•Awakening in 10 min, coherent in 15-30 min

Other examples of Isoflurane (Forane) (Drug Names)

- Enflurane,

- Desflurane,

- Sevoflurane

Nitrous Oxide

•Gas -- "laughing gas"

•Low potency anesthetic

•High potency analgesic

•Amnesia, analgesia, euphoria

•Frequently combined with other inhalation agents

•Lower dose of volatile or IV anesthetics

•No serious side effects (nausea and vomiting)

•Not toxic to CNS

What percentage of nitrous oxide = pain relief of morphine?

20%

General Anesthesia: Inhalation: Volatile Liquids Adverse Effects

•Respiratory and cardiac depression

[Decrease BP, Increase HR and RR, Coughing, laryngospasm, brohchospasm]

•Post-op nausea and vomiting (PONV)

•Shivering after emergence

•Hepatotoxicity

•Malignant Hyperthermia

Malignant Hyperthermia

- Rare, but fatal

•Triggered by certain anesthetics

•Genetic component

What is Malignant Hyperthermia characterized by?

•Profound Elevated temperature

•Hypercapnia

•Tachycardia

•Mixed metabolic/respiratory acidosis

•Mottling and sweating

•Muscle rigidity

•Masseter spasm (rigid jaw)

•Hyperkalemia

•Elevated creatine kinase (CK), myoglobinuria, renal failure

•Dysrhythmias and unstable BP

Malignant Hyperthermia Treatment

•Implement cooling protocols

•*Dantrolene IV

•Oxygenation and hyperventilation

•hydration

General Anesthesia: Intravenous Anesthetics

- Short-acting barbiturates

- Benzodiazepines

- Sedative/Hypnotic

Short-acting barbiturates (Drug Name)

Methohexital (Brevital)

Benzodiazepines (Drug Name)

- Midazolam (Versed)

- Diazepam (Valium)

Sedative/Hypnotic IV Anesthetics (Drug Name)

- Propofol

- Ketamine

Short-acting barbiturates MOA

•Not used as frequently anymore

- Acts as a GABA receptor agonist - enhance & mimic GABA

•CNS: > Depression - no limit

•Respiratory: > Depression, Respiratory Disorders

•Cardio: BP/HR, Heart muscle

Methohexital (Brevital)

Onset: 10-20sec

Duration: 10 min

•

Benzodiazepines MOA

•Potentiate the actions of GABA- binds with GABA receptors

•Limited in CNS depression

•Used as adjunct to many types of anesthesia

•Induction

What can occur when Benzodiazepines are administered in large doses?

•Unconsciousness, amnesia, decrease anxiety, sedation, hypnosis at high doses

Diazepam [Valium]

Onset: 60sec

•Little muscle relaxation/Analgesia

•

Midazolam [Versed]

Onset: 80sec

•Short acting

•>Card/Resp depression

•Conscious sedation

Propofol [Diprovan]

- most widely used IV anesthetic

Propofol [Diprovan] Actions

•Promotes the release of GABA

•Rapid onset - - short duration (recovery in 10 min)

•Amnesia, euphoria, hypnosis

•Antiemetic properties (good for PONV)

Propofol [Diprovan] Uses

•Sedate ICU pts on mechanical ventilation

•the induction and maintenance of anesthesia

•Used in moderate sedation

•No analgesia

Propofol [Diprovan] Adverse Effects

•Pain, burning, stinging at IV site (lidocaine)

•Can cause profound respiratory depression

•Can cause hypotension

•Risk of bacterial infection (emulsion-based formula)

•Low therapeutic Index

Propofol [Diprovan] Contraindications

•Pancreatitis

•Allergy to soybean or soy products, eggs or egg products

Ketamine [Ketalar] Actions

•NMDA receptor antagonist

•Dissociative anesthesia - detached, trancelike effect

•Sedation, immobility, analgesia, and amnesia

Ketamine [Ketalar] Uses

•Minor procedures/diagnostic test

•ICU intubated patients (maintain BP & HR)

•Induction - Emergence -- Full Recovery

Ketamine [Ketalar] Adverse Effects

•Hallucinations, disturbing dreams, and delirium - can last 24 hrs

•Contraindicated in psychiatric disorders

•Recover in calm, quiet environment

•Increases salivation

Morphine

•Bind to opioid receptors in nervous system and tissues to decrease pain

•Supplement sedation, anesthesia, post-op pain

•Narcan is antagonist (antidote)

Fentanyl

- 100x more potent than morphine

- used for sedation on mechanical ventilation

•Bind to opioid receptors in nervous system and tissues to decrease pain

•Supplement sedation, anesthesia, post-op pain

•Narcan is antagonist (antidote)

Morphine and Fentanyl Adverse Effects

•Respiratory depression

•Hypotension

•N/V

•Altered mentation

•Urinary retention

•Itching

Dexmedetomidine (Precedex)

•Sedation, analgesia, decrease anxiety by acting on brain and spinal cord

•No respiratory depression

•Used in surgical, therapeutic, diagnostic procedures and general anesthesia

•Used in ICU mechanical ventilation

Dexmedetomidine (Precedex) Adverse Effects

•Hypotension

•Bradycardia

Moderate Sedation aka...

Conscious Sedation/ "Twilight Sleep"

Moderate Sedation Uses

•Utilized in minor procedures, diagnostic testing, biopsies, outpatient procedures

[Endoscopic procedures, Tissue biopsy]

What is considered a "failed sedation"?

If the patient loses their maintained airway during sedation

What is the difference between general anesthesia and moderate sedation?

Moderate sedation = patient maintains their airway and patient can be aroused with stimuli

Neuromuscular Blocking Agents

•Do not enter the CNS

•Used in conjunction with other anesthetic drugs

•Mainly indicated for producing muscle relaxation during surgery, intubation, and ventilation.

•Non-depolarizing (competitive) and depolarizing - both act on acetylcholine (ach) receptor sites

Competitive "nondepolarizing" Neuromuscular blocking antagonist

•Vecuronium/Pancuronium/Rocuronium

Vecuronium/Pancuronium/Rocuronium MOA

•Competes with acetylcholine for binding to nicotinic receptors- they do not cause receptor activation—they block acetylcholine from activating the receptor - causing muscle relaxation or "flaccid paralysis"

•Titrate to produce weakness to paralysis

Which competitive "nondepolarizing" neuromuscular blocking antagonist is lipid soluble and can build up?

•Vecuronium

Vecuronium/Pancuronium/Rocuronium Adverse Effects

•Respiratory Arrest, weakness, anaphylaxis

• no anesthesia

Vecuronium/Pancuronium/Rocuronium Uses

•Added when more muscle relaxation than IV or inhaled anesthetics provide in surgery or no movement needed for delicate procedures

•Used to facilitate intubation and mechanical ventilation

Vecuronium/Pancuronium/Rocuronium Onset

•in 3-5 minutes

Depolarizing Neuromuscular Blocking Agonist

Succinylcholine

Succinylcholine has a ______ onset and ________ duration.

- rapid

- short

Succinylcholine MOA

- binds to nicotinic receptors on the motor end plate-causing depolarization. It remains bound causing a state of constant depolarization - causing muscle contraction (twitch) followed by paralysis

Succinylcholine Adverse Effects

•post-op muscle pain, Hyperkalemia, Malignant Hyperthermia, bradycardia, cardiac arrest

Succinylcholine Uses

•tracheal intubation (usually when quickly needed or rapid sequence intubation)

Postanesthetic Medications

-Analgesics

-Antiemetic

-Muscarinic Agonists

Postanesthetic Medications: Antiemetics (Drug Names)

•Ondansetron [Zofran]

•Promethazine [Phenergan]

Postanesthetic Medications: Muscarinic Agonists (Drug Name)

•Bethanechol [Urecholine]

Postanesthetic Medications: Muscarinic Agonists MOA

•Direct-acting muscarinic agonist

•Binds reversibly to cholinergic receptors

Postanesthetic Medications: Muscarinic Agonists Uses

•Urinary retention

•GI motility

Nursing Assessment Post op

•Combination of drugs = need for longer recovery

•Frequent assessment of:

•VS (BP, resp rate)

•Respiratory assessment

•Resp depression

•Pulse ox

•Cardiac assessment

•BP

Nausea/Vomiting

Local Anesthetics

•Used to numb a part of the body

•Injection / Catheter / Topical

•Analgesic vs Anesthetic properties

•Can be used alone or in conjunction with other types of anesthesia

Topical anesthetic

•Ointment, lotion, cream applied to skin, mucous membrane, urethra, rectum

•Relieve pain and itching, sunburn, hemorrhoids, sore throat

What is local anesthetics administration referred to as?

"Regional Anesthetics or Regional Blocks"

Regional Anesthetics or Regional Blocks

- Infiltration

- Field Block

- Nerve Block

- Peripheral Nerve Block

- Spinal/Epidural

Infiltration Regional Block

Injected directly into local tissue

Field Block

Nerve blocked in mass to form barrier to surgical site (tooth extraction)

Nerve Block

Used to anesthetize distal extremities injection into distal vein

Peripheral Nerve Block

Injected into or near bundle of nerves at the surgical site

Spinal/Epidural

Injection into the spinal column

- catheter placed

- bolus/continuous

Local Anesthetics Drug Name

- Chloroprocaine (Novocaine)

- Lidocaine (Xylocaine)

- Bupivacaine (used in spinal/epidural)

Chloroprocaine (Novocaine) Type

Ester Type

Lidocaine (Xylocaine) & Bupivacaine Type

Amide Type

Chloroprocaine (Novocaine) Administration

Injection

Chloroprocaine (Novocaine) Course of Action

Onset = 2-5 mins

Duration = 15 min-1 hour

Chloroprocaine (Novocaine) Uses

Dental procedures

Lidocaine (Xylocaine) & Bupivacaine

Administration

Injection & Topical

Lidocaine (Xylocaine) & Bupivacaine Course of Action

Injection: Onset = <2 mins

Duration= 30 min-1 hr

Topical: Onset = 2-5 mins

Duration = 15 min-45 mins