Anesthesia and Nitrous Oxide Quiz

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Questions and Answers

What is the Minimum Alveolar Concentration (MAC) that will likely result in patient awareness?

1.5

1.0

0.5

0.3 (correct)

Which concentration of MAC is required to prevent movement in 95% of patients?

1.3 MAC (correct)

2.0 MAC

1.5 MAC (correct)

1.0 MAC

What is the primary route of administration for Nitrous Oxide in dental practices?

Intramuscular injection

Oral ingestion

Inhalation with O2 (correct)

Intravenous infusion

What is the purpose of administering 100% O2 after a procedure using Nitrous Oxide?

To prevent diffusion hypoxia Signup and view all the answers

How does Nitrous Oxide behave in relation to nitrogen in the middle ear during surgery?

It continues to move until equilibrium is achieved. Signup and view all the answers

Which characteristic of inhaled anesthetics aids in their rapid onset of action?

Low blood-gas solubility Signup and view all the answers

Which is a significant risk associated with the use of Nitrous Oxide?

Diffusion hypoxia Signup and view all the answers

Which factor does NOT influence individual anesthetic requirements?

Ambient temperature Signup and view all the answers

What happens when the concentration of inspired N2O increases?

Middle ear pressure increases due to N2O accumulation. Signup and view all the answers

What is the blood gas solubility of nitrous oxide (N2O)?

0.47 Signup and view all the answers

What is a risk associated with the discontinuation of N2O?

Oxygen dilution in the alveoli due to N2 absorption. Signup and view all the answers

Which of the following is NOT an advantage of using N2O?

Adverse effects on the cardiovascular system. Signup and view all the answers

Which patient group is most likely to benefit from N2O sedation?

Patients with dental anxiety. Signup and view all the answers

What is the primary reason for administering 100% oxygen after N2O sedation?

To wash out the nitrous oxide from the system. Signup and view all the answers

Which statement best describes the elimination of N2O from the body?

N2O is exhaled unchanged from the lungs. Signup and view all the answers

What clinical property does N2O share with oral versed?

Anxiolytic Signup and view all the answers

Which condition is a relative contraindication for the administration of nitrous oxide?

Pregnancy Signup and view all the answers

What is the primary purpose of oral sedation in dentistry?

To reduce stress Signup and view all the answers

Which of the following is NOT a requirement for monitoring a patient under nitrous oxide sedation?

Intravenous drip Signup and view all the answers

Which group of patients is contraindicated for nitrous oxide due to respiratory conditions?

Patients with COPD Signup and view all the answers

What is the recommended pre-oxygenation duration before administering nitrous oxide?

5 minutes Signup and view all the answers

Which of the following is a disadvantage of oral sedation?

Prolonged latent period Signup and view all the answers

In the administration of nitrous oxide, when should the gases be turned on?

Only after the mask is completely sealed on the patient's face Signup and view all the answers

Which component is necessary for proper scavenging during nitrous oxide administration?

Wall suction Signup and view all the answers

What is a common adverse reaction associated with oral benzodiazepines, particularly in the elderly population?

Prolonged drowsiness Signup and view all the answers

Which of the following is the peak plasma level onset time for diazepam?

Within 2 hours Signup and view all the answers

What contraindication is specifically noted for benzodiazepines regarding pregnant women?

Not recommended in first trimester Signup and view all the answers

Which benzodiazepine is specifically not recommended for children younger than 6 years of age?

Chlordiazepoxide Signup and view all the answers

What effect do small dosages of oral benzodiazepines have on respiration?

Do not depress respiration Signup and view all the answers

What is the recommended pediatric dose of diazepam for children?

0.15 to 0.3 mg/kg Signup and view all the answers

Which of the following statements about the mechanisms of action of benzodiazepines is true?

They bind to GABA receptors to cause hyperpolarization Signup and view all the answers

What is a characteristic of oxazepam compared to other benzodiazepines?

It is rapidly absorbed after oral administration Signup and view all the answers

What is the typical maximum dosage for elderly patients taking Flurazepam?

15 mg Signup and view all the answers

Which benzodiazepine has the shortest half-life?

Triazolam Signup and view all the answers

What is a key contraindication for both Temazepam and Flurazepam?

Pregnancy Signup and view all the answers

What is the onset time for Temazepam to exhibit its effects?

20 to 30 minutes Signup and view all the answers

Which of the following benzodiazepines is noted for being a good alternative for patients with liver dysfunction?

Lorazepam Signup and view all the answers

What is the primary concern regarding an overdose of Triazolam?

4 times the recommended dose Signup and view all the answers

What are the side effects associated with Flurazepam?

Staggering, ataxia, drowsiness Signup and view all the answers

What is the recommended dosage of Midazolam for pediatric patients?

0.25 to 0.5 mg/kg with a maximum of 20 mg Signup and view all the answers

What is the primary use of Promethazine?

Antiemetic for nausea and vomiting Signup and view all the answers

Which adverse effect is associated with Promethazine?

Extrapyramidal reactions Signup and view all the answers

What is the maximum recommended dose of Hydroxyzine for adults before a surgical procedure?

100 mg Signup and view all the answers

What is a key feature of the sedation appointment process?

Patients should arrive 1 hour prior to scheduled appointment Signup and view all the answers

What duration of action does Hydroxyzine typically provide?

3 to 4 hours Signup and view all the answers

Which of the following methods is recommended for administering oral sedatives?

By a dentist or staff member Signup and view all the answers

What common property does Hydroxyzine NOT possess?

Antipyretic Signup and view all the answers

Which of the following conditions is NOT indicated for the use of Promethazine?

Management of anxiety Signup and view all the answers

Study Notes

Nitrous Oxide & Oral Sedation

Nitrous oxide (N₂O) and potent volatile halogenated agents make up inhalation anesthetics.
N₂O is inhaled and travels from the alveoli to the pulmonary vasculature, entering the blood-brain barrier to affect the brain.
N₂O is minimally metabolized and excreted unchanged back into the alveoli.
Plasma concentrations of inhalation anesthetics depend on the gas concentration in the alveoli, the solubility characteristics of the individual gases, and cardiac output.
Minimum Alveolar Concentration (MAC) is the end-tidal concentration of an inhaled anesthetic at 1 atm that prevents skeletal muscle movement in response to pain in 50% of patients.
MAC values are general guidelines and individual anesthetic requirements can vary based on factors like higher altitudes, pregnancy, hypothermia, and hyponatremia.
Factors that decrease MAC include higher altitudes (lower barometric pressure), pregnancy, hypothermia, and hyponatremia. Opioids and calcium channel blockers also decrease MAC.
Factors that increase MAC include increased central neurotransmitter levels (MAOIs, cocaine, ephedrine, levodopa), hyperthermia, and chronic alcohol use.
In adults, a 1.3 MAC level prevents movement in 95% of patients, and a 1.5 MAC level blocks adrenergic responses in 95% of patients.
A MAC level of less than 0.3 will likely result in patient awareness.

Inhalation Anesthetics

Nitrous oxide (N₂O) is combined with oxygen (O₂).
N₂O is commonly used in dental offices for anxiolysis and mild sedation.
The procedure does not usually necessitate an escort after completion.
At the end of a procedure, 3-5 minutes of 100% O₂ is administered to prevent diffusion hypoxia.
N₂O has low blood-gas solubility (0.47).
It can be administered to intubated patients during general anesthesia.

Laughing Gas in 1845

N₂O use became a trendy activity at social events and in university settings.

Nitrous Oxide Overview

N₂O in combination with O₂ is the most commonly used sedative agent in dental offices for anxiolysis and mild sedation.
It does not require an escort after the procedure is complete.
Administering 100% oxygen for 3 to 5 minutes at the procedure's conclusion prevents diffusion hypoxia.
The low blood-gas solubility of N₂O (0.47) contributes to its rapid onset and recovery.
N₂O can be administered to intubated patients for general anesthesia.

Middle Ear Surgical Procedures with N₂O

N₂O diffuses from the blood into the middle ear.
N₂O concentrations increase until equilibrium with alveolar concentrations are reached.
Higher inspired N₂O concentrations lead to increased middle ear pressure, potentially causing complications like tympanic membrane rupture.

Pharmacokinetic Properties of N₂O

N₂O is a nonirritating, sweet-smelling, and colorless gas.
Its blood-gas solubility is 0.47.
Onset of action can range from a few seconds to 3-5 minutes.
N₂O rapidly crosses the blood-brain barrier.
It is rapidly eliminated, primarily through exhalation from the lungs, and is not significantly metabolized by the liver or kidneys.
N₂O isn't stored in tissues.

Blood Gas Solubility

The speed at which a gas saturates blood depends upon its blood-gas solubility.
Insoluble gases saturate the blood quickly.
Highly soluble gases saturate the blood slowly.

Diffusion Hypoxia

When N₂O is discontinued, it leaves the blood more quickly than nitrogen, decreasing the blood's O₂ concentration in the alveoli.
This can lead to hypoxia.
To counteract diffusion hypoxia, 100% oxygen is administered for 5 minutes, replacing the N₂O.
The mask should be positioned to receive exhaled nitrous oxide from the patient instead of releasing it into the room.

Clinical Properties

Nitrous oxide is an anxiolytic, similar to oral versed.
It's used as an analgesic for minor and minimally invasive procedures.

Advantages of N₂O

Rapid onset and complete recovery with quick titration to the desired effect.
Relatively safe procedure.
No adverse effects on the liver, kidneys, brain, or cardiovascular systems.
Suitable for providing analgesia and anxiolysis.
Can be used in combination with local and other volatile anesthetics.

Percent of Nitrous Oxide Administered

This data shows the percentages of N₂O based on various liters per minute of N₂O and O₂.

Disadvantages of N₂O

Initial equipment costs and maintenance expenses for sedation can be high.
It may require a significant amount of space.
N₂O may not achieve the same clinical effect in all patients.
Patient cooperation is necessary.

Indications for N₂O

Helpful for reducing dental anxiety and in shorter procedures.
Useful for patients with comorbidities like cardiovascular disease, asthma, and hepatic issues.
Helpful in IV starts.
Helpful in laceration repairs and I&D.

Precautions and Contraindications for N₂O

Patient selection is crucial.
Be cautious with young patients and those with a pre-existing psychiatric history.
N₂O should be used with caution in pregnant women.
Medical contraindications include current otitis media, sinus infections, COPD, and recent MVCs,
Avoid using N₂O for patients with compulsive behaviour issues, claustrophobia, and acute upper respiratory tract infections.

Additional Contraindications for N₂O

Patients with compulsive or behavioral problems.
Claustrophobic patients.
Patients with upper respiratory infections or acute respiratory conditions.

Fasting Before N₂O/O₂ Sedation

Fasting may not be necessary for N₂O/O₂ sedation, but the operator might use ASA guidelines for reference.
Avoid fatty, fried, or greasy food consumption just before the procedure.
A light meal including carbohydrates is safe to consume about 1 to 2 hours prior to the procedure.

Sexual Phenomena Associated With Nitrous Oxide

Reports suggest that N₂O abuse can induce hallucinations and altered sexual perceptions.
Cases of accusations of sexual impropriety against health practitioners after patient sedation have been reported.
Recommendations include continuous supervision and limiting nitrous oxide concentrations to prevent potential overmedication.

Administration of N₂O

Attach the N₂O delivery system to wall suction for proper scavenging.
Visually inspect for leaks in the system prior to use.
Ensure equipment is appropriately positioned and is out of the way, easily visible, during the procedure.
Administer 5 minutes of pre-oxygenation before sedation.

Monitoring Equipment

A patient under N₂O sedation must be closely monitored, typically by an anesthesia monitor, for responses to verbal stimulation, and for oral mucosal color, and to watch for preoperative and postoperative vital signs.

Anatomy of the Mask

Details of the N₂O mask's components and connections are presented.

Nitrous Oxide/Oxygen Breathing Circuits

Noncorrugated tubing in the breathing circuit may become occluded by bending around the dental chair's sides.

Traditional Portable N₂O Unit

Key components of N₂O delivery devices are noted.

Centralized N₂O System

The centralized N₂O system components are shown, including connections and leak sources.

How to Administer N₂O

Open both O₂ and N₂O tanks.
Turn on/off switches.
Adjust the green and blue levers for a 50/50 O₂/N₂O mixture.
Ensure the mask is suitably sealed on the patient to begin administration.

Nitrous Oxide/Oxygen Administration Technique

Assemble and check all necessary equipment.
Confirm functioning scavenging systems.
Review the patient's medical history and ensure informed consent is obtained.
Initiate O₂ flow; fill the reservoir bag.
Use proper minute volume adjustments.
Begin nitrous oxide titration, assessing patient responses promptly.
Continue to adjust N₂O levels to maintain the optimal level of sedation.
Terminate N₂O, and provide 5 minutes of 100% oxygen post-procedure.
Monitor recovery, document treatment, and dispose of used equipment properly.

Details about obtaining informed consent from the patient and/or guardian are delineated in this format.

Components of the Sedation Record

Components of a comprehensive sedation record for a patient undergoing N₂O with O₂ are described.

N₂O/O₂ Sedation Record

Record of the sedation session, including patient information, ASA classification, pain and anxiety levels, medical history, informed consent, procedural data, blood pressure, pulse, respiration, SpO2, minute volume, duration of administered drugs, and post-procedure observations

Nitrous Oxide and Oxygen Sedation Record

Record of procedures including patient details, ASA classification, procedural data, drugs, vital signs, and post-procedure observations

Administration of Nitrous Oxide and Oxygen Sedation Clinical Competency Evaluation

Evaluation criteria for competence in a nitrous oxide and oxygen sedation procedure are presented.

Oral Sedation

The oldest route of drug administration, and frequently used in dentistry.
Oral sedation aims to reduce patient stress before and during dental treatments.

Oral Sedation Advantages

Universally accepted by most patients due to its ease and affordability.
Low cost.
Decreased incidence and severity of adverse reactions.
No needles or special equipment is needed.

Oral Sedation Disadvantages

Oral sedation relies heavily on the patient complying with dosage and timing instructions.
Absorption of medications can be erratic and not completely effective.
Difficult to titrate to the precise level of sedation needed.
Sedative effects can persist for a prolonged period.
Difficult to quickly adjust or reduce sedation levels.

Oral Benzodiazepines in Dentistry

Ideal for managing anxiety.
Acts by binding to GABA receptors and causing hyperpolarization.
Potential for prolonged drowsiness, fatigue, and ataxia.
Increased risk of paradoxical reactions such as agitation, hallucinations, insomnia, and uncontrolled behavior in patients.
Contraindicated with other CNS depressants (drugs like opioids and alcohol).
Pregnant women (especially during the first trimester).

Effects on CNS, Respiratory, Cardiovascular Systems

Reduces anxiety/aggression; acts as CNS depressant.
Potential respiratory depression (especially with larger doses).
Administered alone, in low doses, will not normally inhibit respirations.
Has minor impact on cardiovascular function.
Metabolized primarily in the liver.
Excreted by the kidneys.
Can induce dependence.

Onset of Peak Plasma Levels of Oral Benzodiazepines

Data table showing onset of peak plasma levels for various oral benzodiazepines.

Properties of Benzodiazepines

Table describing peak plasma levels, half-lives, and active metabolites for several benzodiazepines.

Benzodiazepines in Children

Oral diazepam tablets are not recommended for children younger than 6 months old.
Recommended pediatric diazepam dosage is 0.15 to 0.3 mg/kg.
Oral Chlordiazepoxide and oxazepam are not recommended for children under 6.
Clorazepate is not recommended for children under 18.

Chlordiazepoxide (Librium)

Drug class: benzodiazepine.
Slow onset of effects (peak plasma levels developing in 4+ hours) and a gradual reduction in anxiety (may take 1-2 hours).
Not the ideal choice compared to newer benzodiazepines.

Diazepam (Valium)

More potent anti-anxiety effects compared to Librium.
Faster peak plasma levels (within 2 hours).
Can be administered 1 hour before the procedure.

Oxazepam

Short half-life, no active metabolites.
Relatively fast onset and is absorbed quickly.
Effective in cases requiring rapid anxiety reduction or minimal sedation.
Recommended dosage: 10 to 15 mg 3 times daily (TID) for adults.
10 mg TID for elderly patients.

Alprazolam (Xanax)

Peak plasma levels in 1-2 hours.
Relatively long half-life (12-15 hours), meaning the medication remains active longer.
No active metabolites.
Dosage: 0.25 to 0.5 mg three times daily (TID) for adults.
0.25 mg twice daily or three times daily in elderly patients.
Suitable for short to medium half-life circumstances.

Benzodiazepine Sedative-Hypnotics

List of benzodiazepines useful as sedatives.

Flurazepam

Peak plasma levels are achieved within 30-60 minutes.
Metabolized in the liver with a long half-life (47-100 hours).
Side effects include dizziness, drowsiness, lightheadedness, staggering, and ataxia.
Contraindicated in pregnant women.

Temazepam

Absorption is slow after oral administration.
Peak plasma levels take 2-3 hours.
Has a shorter half-life (10 hours) compared to flurazepam.

Triazolam (Halcion)

Short half-life (1.5-5.5 hours) enabling faster onset, useful in dental settings.
Absence of active metabolites.
Suitable for pediatric patients requiring anxiety relief in dental procedures.
Over-dosing is possible.

Lorazepam (Ativan)

Peak plasma levels in 2 hours.
Relatively long half-life (12 hours).
Effective in anxiety and insomnia, suitable for patients with liver dysfunction.
Contraindications include narrow-angle glaucoma.
Side effects include sedation, dizziness, weakness, loss of coordination.

Midazolam (Versed)

Rapid onset (peak effect within 30 minutes).
Actions less noticeable after 8 hours due to faster metabolism.
Offered in syrup form (2 mg/mL).
Dosage varies widely dependent on patient age, weight, and liver function.

Histamine H₁ Blockers (Antihistamines)

CNS depressant properties; useful for inducing sedative effects.
Commonly used to treat allergies, motion sickness, and Parkinsonism.
Available as sedative hypnotics.

Promethazine (Phenergan)

Used as an antiemetic for nausea and vomiting, and as a pre-operative sedative.
A phenothiazine tranquilizer.
May cause extrapyramidal reactions (involuntary muscle movements).
Dosage is up to 50 mg administered one hour before treatment.

Hydroxyzine

Derived from diphenylethanes, with sedative, antiemetic, antispasmodic, and anticholinergic properties.
Effective 15-30 min after ingestion; full effectiveness in 2 hours.
Two available forms: hydrochloride and pamoate.
50-100mg 1 hour before the procedure.

The Oral Sedation Appointment (Adult)

Patient should report 1 hour before the appointment.
Oral sedative is administered in the dental office with 8oz water.
Continuous monitoring is essential.
Assess for appropriate response to sedation at 45 minute mark.
Assist them to the treatment room, and apply appropriate monitoring (pulse oximetry and BP cuff).
Emphasize that sedation won't completely replace local anesthetics.

References

Various papers citing information on oral and nitrous oxide sedation.

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Description

Test your knowledge on the concepts of anesthesia and the use of Nitrous Oxide in dental practices. This quiz covers Minimum Alveolar Concentration (MAC), risks, and benefits associated with inhaled anesthetics. Ideal for dental students and practitioners looking to refresh their understanding of anesthetic principles.