General Anesthetics and Neuromuscular drugs

What is the overall goal for general anesthesia?

Control surgical/procedural pain via CNS depression

Describe the components of an ideal anesthetic

Smooth/rapid loss of consciousness, fast recovery, wide margin of safety, no adverse effects

What are the requirements for general anesthetics?

Loss of consciousness, analgesia, amnesia, inhibition of autonomic reflexes, skeletal muscle relaxation

What are the aspects that can be affected by levels of sedation?

Mentation, airway competency, respiratory system, and cardiovascular system

Balanced anesthesia

drug cocktail to approximate ideal GA that is usually a combination of IV and inhaled anesthetics

What are the three stages of general anesthesia?

Induction, maintenance, emergence

What is the general mechanism of general anesthetics?

Decrease spontaneous and evoked neuronal activity in many brain areas

What are the two types of general anesthetics?

IV and inhaled

CNS depressants

propofol, benzodiazepines, ketamine

What is a difficulty when using IV GA?

difficult to adject dose

What is the primary use of IV GA?

induce anesthesia in adults

What are the effects of propofol

hypnotic, but not analgesic

What is a benefit of using propofol?

Less hangover effect than others due to fast clearance

What are some cautions to using propofol?

Depresses respiratory drive, more CV depression especially in elders

What is the mechanism for propofol?

Via GABAa receptor, potentiating Cl- current

What is the typical opioid analgesic used both intra- and post-operatively for pain control?

Fentanyl

Administration of inhaled GA

via mask or endotracheal tube

What are possible residual effects of GA?

Confusion, delirium, muscle weakness, bronchial secretion accumulation

What population are the possible residual effects most common in?

Older patients due to decreased clearance

What is the site of action for neuromuscular blockers?

Neuromuscular junction

What is the site of mechanism on the skeletal muscle?

Nicotinic ACh receptor at motor end-plate

Depolarizing neuromuscular blocker

succinylcholine

What is a possible residual effect of succinylcholine?

Extended paralysis

Nondepolarizing neuromuscular blocker

cisatracurarium

What is the goal for local anesthetics?

loss of sensation in a specific body part/region

When are LAs typically use?

relatively minor procedures, nonsurgical anesthesia or analgesia

Local anesthetics

Lidocaine, procaine/novocain

Benzodiasepines

midazolam, lorazepam

What are uses for benzodiazepines?

Premedication, sometimes intra-operative

What are specific uses for benzodiazepines?

Anxiolytic, amnesia, sedative

How do benzodiazepines interact with opioids and propofol?

Synergistic effects on CV and respiratory function

What effects do benzodiazepines have on CV and respiratory?

CV depression, depresses respiratory drive

What are uses for ketamine?

anesthetic and analgesic

When might ketamine be used?

Short procedures or for high-risk patients

Why might ketamine be used in high-risk patients over other GAs?

Minimal risk of CV or respiratory effects

What effects can ketamine have?

Produces dissociative anesthesia, psychomimetic side effects

What are cautions for ketamine use?

intracranial pressure, misuse

What are types of inhaled GA?

Volatile liquids, gases

What is the most commonly used volatile liquid for inhaled GA?

Sevoflurane

What inhaled GA is sometimes used for short procedures or labor pain management?

Nitrous oxide

How are inhaled GA administered?

Via mask or endotracheal tube

How are inhaled GAs taken up?

Via gas exchange in lung

What is the target tissue of inhaled GA?

Brain

If a GA is lipid based, what implications could this have post-operatively?

Post-op washout and redistribution can take a longer time if patient has more adipose tissue, confusion, lethargy, disorientation

What is the general mechanism of neuromuscular blockers?

stop neurotransmission at neuromuscular endplate