Week 1: Non-IV Sedation

How does preop anxiety affect oral sedation?

Delays gastric emptying and drug absorption

How can benzodiazepines affect patients with depression?

May worsen signs and symptoms

How does nicotine affect benzodiazepine sedation?

Induces liver enzymes and decreases benzodiazepine effects, potentially requiring higher doses

What do you have to consider when adminitsering drugs in elderly patients?

Decreased plasma protein binding increases free drug

"go low and go slow"

What is different about pediatric sedation physio?

Increased metabolism, challenging airways, and cardiac output dependent on HR

Clark's Rule:

Pediatric dose = (weight in lbs/150) × adult dose

Young's Rule:

Pediatric dose = [age/(age + 12)] × adult dose

Enteral sedation:

Drug absorption through the GI tract (small intestine)

Parenteral sedation routes:

IV, IM, inhalational, intranasal

First-pass effect:

Partial inactivation by liver enzymes before a drug enters systemic circulation

Enterohepatic circulation:

Biliary secretion and re-entry into the small intestine, prolonging drug latency

How do sublingual and rectal routes compare with oral sedation?

They bypass hepatic firstpass/enterohepatic circulation, allowing faster CNS onset

What is the bioavailability advantage of sublingual sedation?

Can increase bioavailability by over 10%

Steady state:

Relatively constant drug concentration after 4 half-lives when accumulation equals elimination

What percentage of steady state is reached after 1, 2, 3, and 4 half-lives?

50%, 75%, 88%, 94%

What are examples of pharmacodynamic interactions?

Antagonism = theophylline/propranolol

Synergism = benzodiazepines/opioids

Latent period:

Time between drug administration and onset of action

What is the latent period for oral, rectal, and IM drugs?

Approx 5-30 minutes

Premedication vs. sedation:

Premedication = gradual onset

Sedation = more rapid clinical action

Oral conscious sedation (California Dental Practice Act):

Minimally depressed consciousness with ability to independently maintain airway and respond to physical stimulation or verbal command

What oral doses are excluded from oral conscious sedation?

Doses at or below the single maximum recommended home use dose

What are disadvantages of oral sedation?

Prolonged latency, erratic/incomplete GI absorption, inability to titrate, prolonged duration

What factors cause erratic oral sedative absorption?

Tissue pH, lipid solubility, mucosal area, gastric emptying, dose, food, bioavailability

Where are most oral sedative drugs absorbed?

Small intestine

Examples of abosrption times:

Liquids 90 minutes

Food and liquids 4 hours

*Anxiety may double the time

Why is giving a second oral sedative dose risky?

First dose may not have peaked

Can cause delayed oversedation, respiratory depression, and loss of consciousness

What is the duration of clinical action with oral sedation?

3-4 hours

What benzodiazepines are used for singledose oral anxiolysis?

Diazepam (Valium)

Lorazepam (Ativan)

Triazolam (Halcion)

Midazolam (Versed, liquid)

Diazepam:

Long half-life (>24 hours due to active metabolites), fast onset, 2.5-10 mg the night before surgery

Triazolam:

Short half-life (2-3 hours), fast onset, 0.125-0.5 mg approximately 1 hour before surgery

What is the peak concentration time for triazolam?

Approximately 1.3 hours

What is the max recommended dose of triazolam (package insert)?

Adult 0.5 mg, elderly 0.125 mg, not recommended under 18 years

What triazolam dose is associated with respiratory depression?

Greater than 2 mg (8 × 0.25 mg tablets)

What factors require triazolam dosage adjustment?

Elderly/frail patients, CNS depressant use, anxiety level, body weight

Which sedatives are listed for single-dose use only?

Diazepam and hydroxyzine

Zaleplon:

Non-benzodiazepine hypnotic, acts at benzodiazepine receptors

Hydroxyzine:

Antihistamine with bronchodilatory, anticholinergic, antiemetic, and antiarrhythmic effects

Promethazine:

Phenothiazine with H1 effects, sedation, anticholinergic and antiemetic actions

Flumazenil:

Benzodiazepine receptor antagonist used to reverse benzodiazepine-induced sedation

What are the adverse effects of flumazenil?

Seizures and cardiac dysrhythmias due to loss of benzodiazepine anticonvulsant protection

What are the limitations of flumazenil reversal?

it reverses sedation but not respiratory depression, so resedation may occur

What is the concern using flumazenil with ketamine?

Using ketamine can cause loss of protective effect against emergence reactions and delusions

How to administer sublingual flumazenil?

Canine to first molar region

2-3 mm under mucosa *not in midline

Why should oral sedatives not be redosed near dismissal?

Delayed peak effect and prolonged action from half-life/distribution characteristics

What fasting interval is best for more predictable oral absorption?

NPO 6-8 hours

How does IM sedation differ from oral sedation?

Avoids GI tract and hepatic first-pass metabolism, more reliable absorption

What is the onset and peak clinical effect of IM sedation?

Onset 5-15 minutes

Maximum effect ~30 minutes

What are the main disadvantages of IM sedation?

Cannot titrate, cannot reverse immediately, prolonged duration, injection injury risk

Why is midazolam (Versed) useful for IM sedation?

Water soluble and better absorbed

What is the safest IM injection site?

Vastus lateralis

What structures must be avoided during gluteal and deltoid injections?

Gluteal = nerve/vascular structures, use upper outer quadrant

Deltoid = radial nerve