Nitrous Oxide

What does the autonomic nervous system control?

(ANS) is predominantly an efferent system, transmitting impulses from the CNS to peripheral organ systems - heart rate, contractile force, contraction and dilation of blood vessels, pupillary size, gland secretions

What are the adverse reactions to N2O2?

(RARE - N2O2 has significant safety in dentistry) - Dizziness - Increasingly rigid movements - Unresponsiveness - Sweating - Nausea/vomiting (PRIMARY REACTIONS) - Dilated pupils (Opthalmic pressure)

What medical conditions are well suited for the use of N2O2?

- Asthma - Epilepsy (seizure disorders) - Cardiovascular or Cerebrovascular disease - Parkinson's Disease - Cerebral Palsy - Multiple Sclerosis - Muscular Dystrophy - Fainting spells

What sensations are effected with the use of N2O2?

- Background sounds are heard better than close sounds. - The gag reflex is also reduced - It does affect sensations such as hearing, touch, pain, and warmth.

When do we take SpO2 readings at SCC?

- Before N2O2 administration - After 100% O2 flush - If patient exhibits any signs of possible complication or overdose

What are the possible behavioral problems associated with oversedation of N20?

- Closing of mouth and/or rigid mandible - Pulling off the mask **If any unusual behavior occurs, follow the 2 lpm rule: - turn nitrous down 2 lpm and oxygen up 2 lpm OR administer 100% oxygen

Explain the various equipment malfunctions that can occur

- Contaminated cylinders - Empty cylinders - Leakage from: ill-fitting mask faulty conduction tubing or reservoir bag poor scavenger system inadequate ventilation - Check equipment frequently

What are adverse side effects of oversedation?

- Diffusion Hypoxia - Nausea and Vomiting - Corneal Irritation - Behavioral Problems

What are the early to ideal N2O2 sedation effects in patients?

- Facial muscles relax - Light-headedness - Tingling/Numbness (hands, feet, lips, etc.) - Wave of warmth - Feeling of euphoria - Light or "floaty" feeling - Heavy feeling - Analgesia

What equipment is needed for N2O?

- Flow meter (Measures liters per minute of gas) - Pressure Gauge Oxygen pressure falls at a constant rate from 2000-2200 psi Nitrous pressure stays at 750 psi until almost empty - Yoke - Gas Hose - Reservoir Bag (3-liter bag allowing ample reserve gas for breathing) - Regulators (Decrease pressure from cylinder to patient) - Warning Whistle (not always present - Goes off when O2 runs out) - Scavenging Nasal Mask (Vacuum system pulls off exhaled gases so nitrous oxide level to operator is minimized - come in 3 sizes) - O2 Flush Button (Delivers 30 l/m of 02 immediately)

What are the heavy to slight overdose N2O2 sedation effects in patients?

- Hearing acute - Visual images confused - ceiling patterns move - Sleepiness - Laughing, crying, dreaming - Less likely to respond to verbal commands - Mouth tends to close - Nausea - Increased movement

What are the ADAs 4 levels of N202 sedation?

- MINIMAL SEDATION: a minimally depressed level of consciousness in which a patient is able to independently and continuously maintain an airway and respond normally to tactile stimulation and verbal commands. Loss of conciousness never occurs - MODERATE SEDATION: depression of consciousness during which patients can respond purposefully to verbal commands - DEEP SEDATION a drug induced state of depressed consciousness accompanied by partial or complete loss of protective reflexes - GENERAL ANESTHESIA a drug induced loss of consciousness during which patients are incapable of being aroused, even with painful stimulation

What are the indications for nitrous sedation?

- Management of fear, anxiety, or mild apprehension - Reduces stress for medically compromised patient - Hyperactive gag reflexes - Temporomandibular disorders - Refusal of anesthesia (general or local) - Reduces pain sensation of dental procedures - Most cooperative children with mild anxiety - Long appointments - Patients with medical conditions

What are the early to ideal clinical signs of N2O2 sedation?

- Mouth remains open - Normal vital signs - Regular breathing - Skin has a slight flush - Patient responds readily to commands - Eyes will glaze over

What is N2O2s relationship with Vit B12?

- N2O administration may lead to severe vitamin B12 deficiency, such as persons with sickle cell disease

How does N2O effect the central nervous system?

- N2O distorts spatial orientation by effects on the cerebellum, making patients feel heavy or light/ floating - N2O also affects the brain stem, which results in the sleepiness generally experienced. - - the brain stem is also involved in movements and sensations in the throat/face/neck, as well reflexes such as eye movements and breathing - - breathing and eye movements are usually not affected at low doses - Memory and mood are affected to a variable degree depending on the concentration of N2O - mild performance impairments in memory - patients typically rate their mood as significantly less alert and calmer during N2O sedation

What are the over sedated clinical signs of N2O2 sedation?

- Nausea/vomiting - Loss of consciousness - Patient responds irrationally - Protective reflexes suppressed - Mouth breathing - Patient uncomfortable - Responds sluggishly - Uncooperative - Uncoordinated movements

When should we discontinue nitrous oxide and increase the oxygen concentration? How should this be done?

- Near the end of the appointment (eg. during tooth polishing), discontinue the nitrous oxide and increase the oxygen concentration to 100%. - Patient should be on 100% oxygen for at 3-5 minutes, or longer if pt feels any grogginess. - If patient is still feeling groggy/nauseous/etc, keep patient on 100% oxygen until feelings subside. - Always verify that SpO2 is equivalent or greater than pre-procedural reading. - Remove nasal hood and clear machine of gas (using 02flush button). - Suggest to your patient that they will feel refreshed and alert as N20 is eliminated quickly. - Make sure that the patient has fully recovered before releasing them.

How does N2O2 effect the cardiovascular system?

- Once in the blood, N2O follows the normal course of the circulatory system - NO EFFECT on heart's contractility, output, stroke volume, rate, or rhythm. - Blood flow to major organs is not significantly affected - Blood pressure effects are dose related, and usually remain within normal limits.

What is the proper management of oversedation of N2O?

1. Observe continually and question your patient to first prevent oversedation. 2. If oversedation occurs, reduce N2O by 1 lpm and recovery to the optimum state should be returned within 30 seconds. 3. Use 100% 02 flush if necessary - (30 lpm of 100% oxygen). 4. Turn off N2O - Use basic life support if necessary 5. Call 911 if needed.

Explain proper N2O2 administration

1. Seat the client, check and record the health history, blood pressure, pulse, respiration, SpO2. 2. Go over health history and informed consent. Ensure no substances in past 48 hours 3. Familiarize pt with procedures: - discuss nasal breathing and nose mask - describe sensations of warmth and tingling - reaffirm the relaxation that the pt will experience - assure the patient that they will be aware of and in control of their actions. 4. Remove contact lenses (optional) 5. Check integrity of equipment - Open gas cylinder valves and check supply. - Find back-up tanks if necessary - Check all lines and hoses for connectivity and good repair - Find an appropriately sized nasal hood for the patient; allow to try on different sizes if necessary 6. Attach the smaller adaptor on the nose mask to the calibrated high-speed vacuum system 7. Set O2 minute volume to 6 liters/minute. (N2O at 0 l/m to begin) 8. Connect scavenger system to high evacuation suction. - Adjust the suction until the steel ball in the calibrator is made to float in the clear zone of the calibrator's window. **(remember, oxygen flow at estimated minute volume 6 L/min) 9. Have pt seat the nose mask on him or herself and adjust it so it is comfortable. 10. The operator should then adjust nose mask tubing to hold the mask in place. Confirm fit with the pt. - If mask is impinging on a sensitive area on the face or if the mask is too big, place a gauze square under the edge of the mask. 11. Give pt clear eye protection so that operator can see patient's eyes throughout procedure. 12. Determine exact minute volume by asking the pt if he or she has enough air to breathe comfortably. - Adjust volume of oxygen per pt response. - If patient feels they are short of breath, increase the volume of the oxygen. - If the patient feels that there is too much air coming into the mask (air is rushing up their nose), decrease the oxygen volume. - Levels may vary from 5 -9 13. Observe reservoir bag for inflation and movement with breaths - If the reservoir bag is being depleted every time the patient takes a breath, increase the total volume of oxygen by 1 liter until the patient can breathe normally. 14. Remind patient to only breathe through their nose. 15. Adjust gas volume up on nitrous, down on oxygen. - If total gas minute volume @ 6 l/m --> 20% nitrous: 1 L/min and 80 % oxygen: 5 L/min 16. Observe the reservoir bag - it should be filled and changing in size with patient's breathing. 17. After 90 seconds check in with the patient - If after 90 seconds this patient is not at "ideal sedation", adjust the N2O up a ½ liter and O2 down ½ liter. (If total gas at 6 l/m, move N2O to 1.5 l/m (25% nitrous and move O2 to 4.5 l/m (75% oxygen) - wait 90 seconds to check level of sedation 18. Introduce nitrous oxide in increments of ½ lpm and reduce oxygen by a corresponding amount each 90 seconds until ideal sedation is achieved ***This is called "titration"

Explain the equipment shut down after dismissing the patient

1. When the O2 flush following nitrous-oxide sedation is complete, remove the nasal hood from your patient while the O2 is still running. 2. Turn the O2 titration knob down (it will not go lower than approximately 2.5 liters/minute) 3. Turn the Nitrous-Oxide tank off with the wrench. 4. Turn the N2O titration knob all the way up. 5. Press the O2 purge until the N2O pressure gauge falls down to zero, and the titration gauge for nitrous also falls to zero. 6. Turn the O2 tank off with the wrench. 7. Turn the O2 knob off (twist and it will extend itself from the unit about 0.5 cm 8. Turn off the scavenging. 9. Remove nasal hood for sterilization; wipe down all machine components

How do healthcare personel avoid diffusion hypoxia?

Dental healthcare providers make practice administration of 100% O2 to patients at the conclusion of N2O-O2 sedation to avoid diffusion hypoxia. ** at the levels of N2O-O2 administered in dentistry, there is little to no risk of diffusion hypoxia, thus this practice may be unnecessary BUT administration of O2 at the conclusion of an appointment is still recommended as placebo, to observe patient recovery, and in allowing expired N2O-O2 to enter the scavenging system

What do we always do following dismissal of a patient whos had N2O2?

Document the experience in the pt's record. Note: - vital signs - concentrations of nitrous oxide and oxygen administered - length of time of sedation and oxygenation - the care provided - pt's response to the sedation.

30 - 40% nitrous is ideal sedation for what percentage of people?

For 70% of people, ideal sedation will be around 30-40% Nitrous Oxide.

How do gases move?

HIGHER --> LOWER PRESSURE

If 42% N2O2 is the max at SCC what does that mean for minute volume of N2O and O2?

IF AT 6 TOTAL LITERS PER MINUTE: N2O = 2.5 liters nitrous per minute = (42% N2O) O2 = 3.5 liters oxygen per minute IF AT 7 TOTAL LITERS PER MINUTE N2O = 2.5 liters nitrous per minute = 36% N2O O2 = 4.5 liters oxygen per minute

What is the management if a patient vomits from oversedation?

If patient vomits: - turn head to side - clear pharynx - turn off nitrous - apply 100% oxygen for 5 minutes

What occurs when too LITTLE air is supplied? What about too MUCH air?

If too little air is supplied the patient will have difficulty breathing and a suffocating feeling. If too much air is supplied, contained gases will be wasted - patient's eyes will dry and operator exposed to excess gases

What is titration?

Introducing nitrous oxide in increments of ½ lpm and reduce oxygen by a corresponding amount each 90 seconds until ideal sedation is achieved

How is N2O2 metabolized?

It does not combine with any body tissues and so is NOT metabolized. **It enters the body through the lungs and exits unchanged through the lungs.

When was Nitrous oxide first used in dentistry? When and why was it combined with oxygen?

It was first used in dentistry in 1844. In 1868 it was combined with oxygen for use in pain control.

Who discovered nitrous oxide and when?

Joseph Priestly discovered nitrous oxide in 1772

What are the symptoms of diffusion hypoxia?

Lack of oxygen to tissues - headache - feel groggy - nauseated - "hung-over" **These symptoms are typically reported after completion of procedure

What is the intended sedation level of nitrous in dentistry?

MINIMAL SEDATION

What percentage of N2O do most patients reach adaquate sedation levels?

MOST PATIENTS REACH ADEQUATE SEDATION LEVELS AT 15% TO 40% N2O

What are the ratios of Nitrous and oxygen when providing N2O2 sedation? How does this compare with atmospheric air?

N2O-O2 sedation typically provides: 30% N2O and 70% O2 atmospheric air typically provides: 78.06% N2, 21% O2, 0.04% CO2

What is the absolute maximum dose of N2O? What is SCCs maximum level of N2O?

NEVER exceed the absolute maximum dose of 70% N2O Maximum level of N2O at Seattle Central should not go over 42% unless under close supervision of RDH/DDS - This translates to 2.5 lpm of Nitrous and 3.5 lpm of Oxygen in a minute volume of 6L.

Is pain perception BLOCKED with N2O2 use?

NO so local anesthesia may still be necessary.

What are the differences in tank size with the O2 and Nitrous?

Nitrous: BLUE Full tank 750 psi (650-900 psi) Oxygen: GREEN Full tank = 2100 psi

What kind of solubility does nitrous have?

POOR solubility in blood and rapidly leaves the blood when it's partial pressure is higher than in surrounding tissues.

How does N2O2 effect the GI?

Pressure increases can expand air spaces worsening intestinal obstruction May cause nausea

Explain the hose system for nitrous administration

The sterilized nose mask connects to two hoses coming off each side of it and each pair of hoses is joined by an adaptor. - The larger adaptor connects to the gas hose. - The smaller adaptor connects to the high-speed suction system.

Why is autism a relative contraindication?

Though there is currently no direct evidence of exceptional risk, it is seen that some individuals with autism have altered vitamin B12 and folate metabolism. Further investigation is warranted.

What side of sedation should we always adjust to? Can the patients sedation level alter during the appt?

We adjust to the lighter side of sedation rather than to oversedate. YES - Patient's sedation may alter during the appointment so be alert to alter N20 accordingly. Ex., the rubber dam may change their breathing pattern. **If signs or symptoms of excessive sedation, or any adverse reactions, back off the nitrous and increase oxygen, OR switch to 100% oxygen until resolved.

Is N2O a CNS depressant?

YES - the cerebral cortex receives all sensory input via the thalamus - N2O produces a DECREASED sensory perception that reduces an individual's ability to react to pain through it's effects on the thalamus and cortex

Can N2O2 be beneficial for certain heart conditions?

YES such as hypertension angina pectoris, and some congenital conditions BECAUSE: - N2O-O2 has a positive effect on myocardial ischemia due to provision of supplemental oxygen - dilates peripheral vessels, thus lessening the work needed to move blood - by reducing stress and increasing available O2, cardiac patients are LESS LIKELY to have an adverse reaction during treatment

Does nitrous have an odor?

Yes, COLORLESS sweet odor

Define sedation

a state of calm induced by a drug or other tranquilizing substance

What is nitrous oxide?

a weak anesthetic, but strong analgesic . raises a patient's threshold for pain.

What can nitrous oxide sedation provide to the patient?

addresses both FEAR and PAIN, and provides mild amnesia that tends to shorten the perception of appointment length. - N2O-O2 also increases levels of tolerance and cooperation - rapid onset and short recovery times

What is respiration rate?

breaths per minute. (adult average 12 breaths per minute)

What effect does N2O2 have on the ANS (Autonomic nervous system)?

little effect on ANS with normal dosing

What is diffusion hypoxia?

may occur when excess levels of N2O diffuse out of the blood, displacing O2 in the lungs - this usually occurs when excess percentages of N2O have been administered - this results in reduced O2 blood saturation

Have deaths been reported with N2O2?

no deaths have been reported following appropriate protocols for administration and properly functioning equipment

Can nitrous oxide be unpredictable?

some individuals may respond in unpredictable ways to stress and anxiety. N2O-O2 alone or in combination with local anesthetic may prove insufficient to allow these patients to tolerate therapy.

What does poor solubility mean?

that only a small percentage of nitrous oxide inhaled will be removed via blood absorption, so a state of equilibrium is quickly established between the concentration of nitrous in the blood and in the alveoli.

What happens if the patient is breathing through their mouth instead of in and out of their nose?

the nitrous is not getting into their system. Even worse, they are breathing out the nitrous into an unscavenged area in which the dental personnel is breathing it in. **Make sure the patient is nose breathing throughout the procedure!

What is tidal volume?

the volume of air with each breath (average 500ml)

What does nitrous solubility mean for sedation purposes?

this means the onset of nitrous oxide sedation is rapid, and the effects are also rapidly eliminated when nitrous is removed.

What is minute volume?

volume of air required per minute (Tidal volume) x (Respiration rate) = Minute Volume **adult average minute volume is 6-7 liters per minute

How do we as clinicians reduce N2O concentrations from 900 to 30 ppm?

By using combinations of the following: - scavenging system - use a well-fitting mask on the patient - discourage talking and mouth breathing - use proper ventilation - use a fan - wear a badge - open a window

How should titration be done? What should never be done when altering N2O and O2 levels?

Correct titration - As you turn up N2O, turn O2 down to stay at the same total flow. NEVER reduce oxygen below 2 - 3 liters while in use!

What are the relative contraindications of N2O2?

- Patient doesn't want N20 - Communication and cooperation difficulty (Ex., language barriers- constant communication is necessary when administering Nitrous Oxide.) - You also need your patients to cooperate and respond to your directions. - Nasal obstructions (deviated septum, cold, sinus infections, allergies) - Middle ear disturbances (N20 causes increased pressure on the tympanic membrane.) - Cystic fibrosis - B12 deficiencies (possibly Autism, sickle cell disease) - Pregnancy (FDA pregnancy category C - N20 does cross the placenta- fetus will experience the same CNS depression as the mother. May be used in 2nd or 3rd trimesters; obtain medical consult prior) **N2O is used during labor and delivery. - Personality disorders and emotional instability (Mental illness, retardation, autism, Alzheimer's, chemical dependency; N2O can cause distortion of time and reality - Unpleasant feelings may surface) - Bowel obstructions or colostomy bags (Air spaces in the gut can be displaced by N20) - Claustrophobia or PTSD (Patient may feel threatened by the nasal hood and mask. - Phobic individuals may actually resist the calming effects of N20; making the situation worse.) - Severe behavior problems (Especially children)

Why is it important to administer 100% oxygen for at least 3-5 minutes to a patient following N2O sedation?

- Provides an O2 flush: provides the total tidal volume of oxygen to flush nitrous oxide out of the system - Prevents diffusion hypoxia: not enough oxygen is getting to the tissues - Can happen after room air is breathed right after nitrous is shut off - Diffusion hypoxia effects peak 2-5 minutes after nitrous oxide is discontinued

What is "percent of nitrous oxide" refer to?

- Pts should always receive at least their minute volume of total gases (nitrous oxide and oxygen). - Total levels of flow vary from 5-9 liters/minute per individual. - "Percent of nitrous oxide" is the term we usually refer to when administering N20/02 sedation. **Most people reach adequate sedation between 15% and 40% N2O

What are nitrous oxide goals?

- Relieves anxiety & fear - Stress reduction - Reduces pain perception - Amnesia & analgesia effects - Light sedation & mood alteration - Patient remains conscious with protective reflexes intact

What is a nitrous oxide scavenging system?

- Scavenging system removes excess nitrous oxide - Minimizes trace amounts of nitrous oxide before, during, and after use by the patient - Use a scavenging nasal mask

What are the advantages of nitrous oxide?

- Simple and safe - No allergies - Reduction in gag reflex - Onset & recovery are fast - Time perception can be altered

How do the upper respiratory tract and lower respiratory tract differ in function?

- Upper respiratory tract: warms, humidifies, and filters inspired air. - Lower respiratory tract: performs gas exchange at alveoli and capillaries via partial-pressure gradients. Gases move from higher to lower pressure

What are the disadvantages of nitrous oxide?

- Vertigo, nausea, vomiting - Extreme behavior problems cannot be managed well (some pts may not be able to receive nitrous) - Equipment is cumbersome - Mask gets in the way (especially on the maxilla) - Long term exposure may cause health problems

List the benefits of nitrous oxide

- addresses both fear and pain - mild amnesic effects (shortens the perception of time) - Facilitates positive behaviors in pedo patients - Allows easy titration of gases delivered to pt - Rapid onset of sedation (30 secs - 5 mins) - Short recovery times (3 - 5 mins)

What are the absolute contraindications of N2O2?

- advanced COPD - active respiratory infection (URI, TB, influenza, etc) - 1st trimester pregnancy - intraocular gas injection within 8-12 weeks - severe psychosis - latex allergy (unless a latex-free delivery system) - recent tympanic membrane grafting - treatments involving the injection of gases into any body cavity

List the limitations of nitrous oxide

- expresses variable effects (ineffective for some) - Increases costs - Requires education to safely administer/ monitor - Requires routine equipment monitoring/maintnence - Requires monitoring to prevent environment exposure

What is the percentage of N2O if: N2O is 1.5 l/m and O2 is 4.5 l/m?

Always divide percentage of N2O used over the TOTAL MINUTE VOLUME! N2O is 1.5 l/m and O2 is 4.5 l/m Minute volume = 1.5 + 4.5 = 6 l/m 1.5 liters nitrous per minute/ 6 total liters per minute = 25% N2O REMEMBER At SCC we do not recommend exceeding 42% N2O2, and you should never exceed 70%

Define Anesthesia and Analgesic

Anesthesia: loss of pain Analgesia: loss of the sense of pain while conscious

How should the degree of contraindications be evaluated?

At an individual case basis - It may be necessary to obtain a medical consult with patients physician to determine individual sensitivity

What is corneal irritation?

Caused by leakage of gas from mask Dries the eyes and can cause irritation Instruct patient to remove contact lenses or keep eyes closed during procedure **Should not be an issue if the mask fits properly

What is the nausea and vomiting caused by?

Caused by: - Too much nitrous - Lack of titration - Eating a large meal before appointment - "Seesawing" nitrous levels To help with nausea: - Take patient off N2O and administer 100% O2 - Reassure the patient that they will feel better after receiving oxygen

What is a pulse oximeter? What are the different saturation levels?

SpO2 - A pulse oximeter measures blood oxygen saturation levels Normal: 94 - 99% Mild-respiratory disease: 90% and above Supplemental oxygen recommended below 90%

How is nitrous stored? How is it delivered?

Stored as liquid (BLUE cylinder) Delivered as gas

What are possible hazards to clinicians?

Studies conducted on operating room personnel, oral surgeons, and others who are chronically exposed to nitrous oxide (1000-15,000 ppm) have shown: - spontaneous abortions - birth defects - bone marrow suppression - anemia - hepatic and renal disease - cancer

What are pin and note tag systems?

TANK SYSTEMS - Pin systems help ensure proper connectivity - Note tag system (Empty -- In Use / In Service --Full (unused))

Does the ADA affirm the use of nitrous oxide?

The ADA consistently reaffirms the use of local anesthesia, N2O-O2 sedation, and general anesthesia as common, well-recognized strategies for controlling pain and anxiety in dentistry.