Nitrous Oxide & Oral Sedation PDF

Nitrous Oxide & Oral Sedation Marcus Crayton, DDS Howard University Hospital Oral & Maxillofacial Surgery, PGY-3  Minimum Alveolar Concentration  MAC is the end tidal concentration of an inhaled anesthetic at 1 atm that prevents skeletal muscle movement response to...

Nitrous Oxide & Oral Sedation Marcus Crayton, DDS Howard University Hospital Oral & Maxillofacial Surgery, PGY-3  Minimum Alveolar Concentration  MAC is the end tidal concentration of an inhaled anesthetic at 1 atm that prevents skeletal muscle movement response to a painful stimulus in 50% of patients.  MAC values are general guidelines and individual anesthetic requirements can be influenced by a variety of factors  MAC values are additive.  In adults, a level of 1.3 MAC will prevent movement in 95% of patients and a MAC of 1.5 will block an adrenergic response in 95 % of patients. MAC of less that 0.3 will likely result in patient awareness. Inhalation Anesthetics  Consist of Nitrous Oxide (N2O) and potent volatile halogenated agents.  Inhaled and cross from the alveoli into the pulmonary vasculature to enter the blood brain barrier leading to effects within the brain.  Minimally metabolized and are excreted unchanged back into the alveoli.  Plasma concentrations of the inhaled anesthetics are dependent on the concentration of the gas within the alveoli, solubility characteristics of the individual gases, and cardiac output. Laughing gas in 1845 Poster advertising a nitrous oxide exhibition N2O use became the trendy activity at social events and in university settings  Nitrous Oxide Overview  N2O in combination with O2 is the most commonly used sedative agent.  It administered in dental offices for anxiolysis and mild sedation.  Does not require an escort after completion of the procedure.  At the conclusion of procedure, 3 to 5 minutes of 100% O2 to prevent diffusion hypoxia.  Low blood-gas solubility of 0.47  Can be administered to intubated patients for general anesthesia.  2nd Gas Effect Middle ear surgical procedures with N2O N2O will diffuse from the blood into middle ear Because it is 34 times more soluble than nitrogen N2O will continue to move into the space until equilibrium is achieved with the alveolar N2O concentration. The higher the concentration of inspired N2O, the more N2O accumulates in the occluded middle ear, resulting in increased middle ear pressure because of the rigid confines. Tympanic membrane rupture, graft displacement, and other complications observed PHARMACOKINETIC PROPERTIES of N2O  N2O is nonirritating, sweet smelling, and colorless gas.  Blood gas solubility of 0.47  Onset anywhere from a few seconds up to 3- 5 minutes  Crosses the blood-brain barrier rapidly Elimination  Rapid elimination  Unchanged with exhalation from the lungs  No significant metabolism by the liver or kidneys  Not stored in the tissues Blood Gas Solubility Diffusion Hypoxia  When N2O is discontinued, it leaves blood more quickly than nitrogen (N2) from the air is absorbed.  The combination of N2O and N2 in the alveoli dilute O2 in the alveoli which can lead to hypoxia.  Administer 100% oxygen for 5 minutes at the end of Nitrous sedation to wash out the nitrous at the end of procedure.  Use mask so the exiting Nitrous is exhaled into the mask instead of the room. DIAGRAM OF DIFFUSION HYPOXIA  Clinical Properties  Anxiolytic: Similar to oral versed  Analgesic: For minor and minimally invasive procedures  Advantages of N2O  Rapid Onset  Quick recovery & Complete recovery  Able to titrate to effect  Relative Safe procedure  No adverse effect on liver, kidney, brain or cardiovascular systems  Can provide analgesia and anxiolysis  Can also be used in combination with local anesthesia & other volatile gases PERCENT OF NITROUS OXIDE ADMINISTERED Disadvantage of N2O  The initial cost of equipment required for sedation is high.  The cost of maintaining the (O2 & N2O) can be high.  Can require a significant amount of space.  Does not achieve the same clinical level of effect in all patients.  Requires a degree of cooperation from the patient. Indications for N2O  Great for patients with dental anxiety  Nitrous is generally used for shorter/brief procedures,  Helpful in patients with different comorbidities  Cardiovascular disease  Asthmatic Patients  Hepatic Disease  IV starts  Nitrous provides some venous dilation!  Laceration repairs & I&D Precautions & Contraindications for N2O  Patient Selection is imperative!  Precaution when administering N20 to young patients or patients with history or preexisting psychiatric disorders.  Relative contraindicated in pregnancy.  Medical Contraindicated in patients with current otitis media, sinus infections, COPD, and recent MVC. Additional Contraindications  Patients with a compulsive personality or behavior problems.  Claustrophobic patients.  Upper respiratory tract infections or acute respiratory conditions. Additional Contraindications FASTING OR NOT FASTING BEFORE N20/02 SEDATION AN ISSUE OF SPECIAL CONSIDERATION  ADMINISTRATION OF N2O  Attach to wall suction for proper scavenging  Visually inspect for leaks  Attach appropriately sized mask set-up  Make sure equipment is out of the way but visible  to the provider performing the procedure  5 minutes of pre-oxygenation per policy Monitoring Equipment  A patient under nitrous oxide sedation shall always be visually monitored by the permit holder or by an anesthesia monitor.  The patient shall be monitored as to response to verbal stimulation, oral mucosal color and preoperative and postoperative vital signs.  Required Armamentarium  Pulse Oximeter  Cardiac Monitor  Blood Pressure Cuff  Scavenging Nasal Hood ANATOMY OF THE MASK N2O-O2 breathing circuits. Noncorrugated tubing can become occluded as it bends around the sides of the dental chair. Traditional Portable N2O Unit Centralized N2O System How to Administer N2O 1. Open both tanks (O2 & N2O). 2. Turn On/Off Switch to On. 3. Adjust the green & Blue levers to administer a 50/50 mixture of O2 & N2O. 4. Never turn on the gases until the mask is sealed on the patients face. NITROUS OXIDE/ OXYGEN ADMINISTRATION TECHNIQUE BY TITRATION TECHNIQUE COMPONENTS OF THE SEDATION RECORD  Oral Sedation  The oldest route of drug administration and most commonly used in dentistry.  Purpose is to reduce stress before and during dental treatment. Oral Sedation Advantages 1. Almost universal acceptability. 2. Ease of administration. 3. Low cost. 4. Decrease incidence of adverse reactions. 5. Decrease severity of adverse reactions. 6. No needles, syringes, or equipment. Oral Sedation Disadvantages 1. Reliance on patient compliance. 2. Prolonged latent period. 3. Erratic and incomplete absorption of drugs from the GI tract. 4. Inability to titrate. 5. Inability to readily lighten or deepen the level of sedation. 6. Prolonged duration of action. Oral Benzodiazepines in Dentistry  Ideal drug for management of anxiety.  Mechanism of Action  Binds to GABA Receptor of Cl- Channels to cause hyperpolarization.  Adverse reactions  Prolonged drowsiness, fatigue and ataxia (especially in elderly population)  Paradoxic reactions (excitement, hallucinations, insomnia, and rage)  Contraindications  In combination with other CNS depressants (alcohol, opioids, etc)  Pregnant women (especially 1st trimester) Oral Benzodiazepines in Dentistry  Effects on CNS  Reduction of hostile and aggression  CNS depressant  Effects on respiratory system  Potential respiratory depression in large dosages.  Administered alone in small dosages alone don’t depress respirations.  Effects on Cardiovascular system  Virtually no change in cardiovascular function.  Mostly metabolized by the liver  Absorbed in the GI tract  Renally excreted  Dependence Onset of Peak Plasma Levels of Oral Benzodiazepines Properties of Benzodiazepines Benzodiazepines in Children  Use of oral diazepam tablets in children younger than 6 months of age is not recommended.  Recommended pediatric dose of diazepam range from 0.15 to 0.3 mg/kg.  Oral forms of Chlordiazepoxide and oxazepam are not recommended for children younger than 6 years.  Clorazepate is not recommended in patients younger than 18 years. Chlordiazepoxide (Librium)  Drug Classification: benzodiazepine  Peak plasma levels that don’t develop for 4 hours!  Adequate anxiety reduction that may develop 1 to 2 hours.  Slow onset for anxiolysis.  Not ideal compared to newer medications. Diazepam (Valium)  Considered to have a greater antianxiety effect than Librium.  Peak plasma level within 2 hours.  May be administered 1 hour before.  Suggested Premedication dose of 5 to 10 mg 1 hour before bedtime  For elderly patients and patients who are ASA III or IV  Recommend dose of 2 to 2.5mg  Not Recommended in children younger than 6 months of age. Oxazepam  Short elimination half life with no active metabolites.  Drowsiness typically only seen in doses of 60 mg or more.  Rapidly and reliably absorbed after oral administration.  Peak of plasma levels within 1 to 4 hours.  Dosage  Adult dosage: 10 to 15 mg tid.  Elderly patient 10mg tid Alprazolam (Xanax)  Peak plasma levels within 1 to 2 hours orally.  Half life of 12 to 15 hours  No active metabolites  Dosage .25 to 0.5mg tid.  Elderly patients.25mg bid or tid. Benzodiazepine Sedative-Hypnotics  Flurazepam  Temazepam  Triazolam  Lorazepam  Midazolam Flurazepam  Peak Plasma levels develop within 30 to 60 mins.  Metabolized in the liver.  Long half life of 47 to 100 hours.  Side effects  Dizziness, drowsiness, lightheadedness, staggering, and ataxia.  Contraindicated in pregnant women  Dosage  30mg taken 1 hour before bedtime in adults.  15mg for elderly patients Temazepam  Absorbed slowly after oral administration.  Onset occurs within 20 to 30 mins.  Peak plasma levels require 2 to 3 hours.  Half life is 10 hours with no significant active metabolites.  Mostly used for patients having difficulty remaining asleep.  Dosage  30mg 1 hour before bedtime  15mg for elderly patients.  CI in pregnant women Triazolam (Halcion)  Available forms: Tabs 0.125, 0.25 mg  Great for dentistry because of short half life of 1.5 to 5.5 hours  No active metabolites.  Effective in pediatric population for anxiety and minimal sedation.  CI in pregnant patients.  Overdose can occur at 4x recommended dose  Adverse reactions  Drowsiness, headache, dizziness, nervousness.  Dosage .25mg 1 hour before dental treatment .125 to 0.25mg for elderly patients. Lorazepam (Ativan)  Available forms: Tabs 0.5 mg,1,2 mg; inj 2, 4 mg/ml; oral solution 2 mg/ml  Peak plasma levels develop in 2 hours.  Mean half life of 12 hours.  Effective as a antianxiety and hypnotic drug.  Good alternative for patient with liver dysfunction.  CI for patients with narrow angle glaucoma.  Adverse reactions  Sedation, dizziness, weakness, and ataxia.  Preoperative Dosage  2 to 4 mg 1 hour prior to appointment.  Midazolam (Versed)  It is prepared as a syrup in a concentration of 2mg/ml.  Peak action after oral administration occurs within 30 mins.  The actions of midazolam are less apparent after 8 hours than those  of other benzodiazepines  Adult Dosage  15mg taken 1 hour before bed.  Pediatric Dose  0.25mg to 0.5mg/kg. (max dose of 20mg)  CI in patients with renal or hepatic function. Histamine H1 Blockers (Antihistamines)  CNS depression (sedation and hypnosis)  Used primarily for allergies, motion sickness and parkinsonism  Marketed as sedative hypnotics. Promethazine (Phenergan)  Used as an antiemetic for management of nausea, vomiting and preoperative sedation.  A phenothiazine that is classified as a antipsychotic.  Indicated to decrease agitation, hostility, combativeness and hyperactivity.  They do not produce respiratory depression or depress the CV.  Can produce extrapyramidal reactions  Akathisia  Acute dystonia  Parkinsonism  Tardive dyskinesia  Dosage  25 to 50mg 1 hour before treatment  Pediatric dose is 2.2 mg/kg  Hydroxyzine  Derived from a drug class called diphenylethanes.  Possesses sedative, antiemetic, antispasmodic, anticholinergic properties.  Two forms of drug available.  Hydroxyzine hydrochloride (Atarax)  Hydroxyzine pamoate (Vistaril)  Rapidly absorbed from GI tract within 15 to 30 mins.  Maximal clinical action develop in 2 hours with a duration of action of 3 to 4 hours.  Dosage  50 to 100mg 1 hour preoperatively.  Can be administered in liquid form for children at 1.1 to 2.2mg/kg.  Used for children with mild to moderate fear The Oral Sedation Appointment (Adult)  Patient should report 1 hour prior to scheduled appointment.  Oral sedative drug is administered to the patient with 8 oz of water in the dental office by dentist or staff member.  Patient should be kept in area where they can be monitored constantly.  At the 45 minute mark the patient should be evaluated to determine if the appropriate response has occurred.  Assist the patient when walking to treatment room.  Appropriate monitoring with pulse oximetry and BP cuff.  Remember that sedation is not a substitute for local anesthesia.  Conclusion of treatment. References Miloro, M., Ghali, G.E., Larsen, P. and Waite, P. (2022) Peterson’s Principles of “Oral and Maxillofacial Surgery”. 4th Edition, Shelton Connecticut, People’s Medical Publishing House, 841-8G1. Malamed, Stanley F. Sedation: A Guide to Patient Management. Elsevier, 2018.