The Administration of Nitrous The Administration of Nitrous Oxide/Oxygen AnalgesiaOxide/Oxygen Analgesia

Idaho State Board of Dentistry Expanded Function

Background InformationBackground Information

The Nitrous oxide gas was discovered by Joseph Priestly in 1772.

In 1844 Dr. Horrace Wells observed Gardner Quincy Colton demonstrate the exhilarating effects of nitrous oxide and requested he use it on him during dental treatment.

In 1868, Dr. Edmund Andrews, a Chicago surgeon, established the need to mix oxygen with nitrous oxide for use in operations of long duration.

In 1903, Dr. Charles Teter, a Cleveland dentist, invented the first nitrous oxide-oxygen machine.

The first “fail-safe” system was marketed in 1962

Nitrous Oxide/Oxygen in Nitrous Oxide/Oxygen in DentistryDentistry

Nitrous oxide is employed in dentistry for the primary purpose of reducing anxiety in the dental patient.

It is estimated that 20 to 40 million adults in America avoid dental treatment because of fear.

Properties of Nitrous OxideProperties of Nitrous Oxide

Nonirritating, colorless gas with a sweet taste and odor.

Is a true general anesthetic.Least potent of all anesthetic gases.Travels through the blood stream in a free

gas state.Total saturation in the blood occurs within 3

to 5 minutes.

Pharmacological EffectsPharmacological Effects

Total circulation time for one breath of nitrous oxide/oxygen is 3 to 5 minutes.

No changes in the heart rate (pulse) or blood pressure.

Changes in respiratory rate are related more to the relaxation of the patient than to the nitrous oxide itself.

Nonirritating to the lungs

Side EffectsSide Effects

Nausea and vomiting are the most common side effects. The incidence increase:

With prolonged administration or rapid induction With higher concentrations Following a heavy meal Following fasting (empty stomach) In motion sickness sufferers or patients with

previous history of vomiting

Adverse ReactionsAdverse Reactions

HypoxiaBone Marrow DepressionPressure/Volume EffectPsychologic ReactionsFireProtective Reflexes

Average Effects of Nitrous Oxide/Oxygen with Average Effects of Nitrous Oxide/Oxygen with

Various Concentrations of Nitrous OxideVarious Concentrations of Nitrous Oxide 100% will produce anoxia. 80% will produce hypoxia with hallucinations and

bizarre dreams; may cause respiratory, cardiovascular, kidney or liver damage.

65% can cause patients to enter the excitement stage.

35% usually provides maximum analgesia with maintenance and cooperation of the patient.

25 % is claimed as analgesic as 10 mg morphine sulphate.

Anesthesia and AnalgesiaAnesthesia and Analgesia

Anesthesia produces a lack of all sensation.Analgesia creates a decreased ability or

inability to perceive pain.Sedation is the calming of a nervous

apprehensive patient without loss of consciousness.

Stages of AnesthesiaStages of Anesthesia

Analgesia: the patient is conscious and cooperative. Pain reaction is decreased.

Delirium: is the excitement stage. The patient becomes extremely stimulated, raged and possibly angry. Loss of consciousness begins in Stage II. Delirium is an undesirable effect; therefore, it should be avoided.

Surgical: the patient is unconscious and life support is required. There is a total lack of sensation.

Respiratory Paralysis: death occurs in this stage.

Analgesia: Clinical Effects Analgesia: Clinical Effects Plane 1Plane 1

Patient appears normal, relaxed, and awakePatient my feel slight tingling in toes,

fingers, tongue, or lipsPatient my giggleVital signs remain normalThere are no definite clinical manifestations

Analgesia: Clinical Effects Analgesia: Clinical Effects Plane 2Plane 2

Patient may have a dreamy lookReactions of patient are slowedPartial amnesia may occurVoice will sound “throaty”Patient will feel warm and drowsyPatient may drift in and out of environment

Patient may hear pleasant ringing in earsVital signs remain normalPain is reduced or eliminated but touch and

pressure is still perceivedPatient is less aware of surroundings;

sounds and smells are dulled

Analgesia: Clinical Effects Analgesia: Clinical Effects Plane 3Plane 3

Patient becomes angry with hard stare Patient’s mouth tends to close frequently Patient no longer cooperates Patient is totally unaware of surroundings Patient may hallucinate Patient’s chest may feel heavy Sensation of flying or falling or uncontrolled

spinning Pupils may dilate

Primary Indications of UsePrimary Indications of Use

Fear and anxietyPatient who refuses or is allergic to local

anesthesiaProminent gag reflexPatient who gets impatient at long

appointments

Indications with Special Indications with Special ConsiderationsConsiderations

Cardiovascular diseaseCerebrovascular diseaseRespiratory disease: asthmaHepatic (liver) diseaseEpilepsy and other seizure disordersPatients taking tranquilizers, analgesics,

antidepressants or hypnotics

Contraindications of UseContraindications of Use

Nasal obstructions – common cold, upper respiratory infections, allergies, or deviated nasal septum

Chronic Obstructive Pulmonary Disease Debilitating cardiac or cerebrovascular

diseasePregnancy

Patients with psychiatric disorders or compulsive personalities

Claustrophobic patientsChildren with severe behavioral problemsThe patient who does not want nitrous

oxide/oxygen

EquipmentEquipment

Nitrous oxide tank – always blueOxygen tank – always greenNitrous oxide/oxygen machineBreathing apparatus

– Full face mask– Nasal hood– Nasal cannula

Equipment Safety FeaturesEquipment Safety Features

Pin index and diameter index safety system makes it virtually impossible to attach the nitrous oxide and oxygen tanks wrong

Minimum oxygen liter flow assures that 2.5 –3 L/min. of oxygen is the minimum amount that can be administered

Oxygen fail-safe system is designed so that the nitrous oxide will automatically turn off when the oxygen is depleted

Emergency air inlet allows room air to enter the system when the oxygen fail safe system turns gases off so that the patient can continue to breathe through the nasal hood

Fail-safe alarm sounds when the fail safe system turns off the gases.

Oxygen flush button allows for 100 % oxygen to be administered through the reservoir bag in the event of an emergency

Color coding – Knobs, tanks, and sometimes tubing are color-coded blue for nitrous oxide and green for oxygen

Texture of knobs – some machine knobs are textured differently to differentiate between the nitrous oxide and oxygen

Preparation for Administration Preparation for Administration of Nitrous Oxide/Oxygenof Nitrous Oxide/Oxygen

Have patient visit the restroomComplete thorough medical historyTake and record vital signs of patientALWAYS BE POSITIVE when discussing

techniques and effects, be honest but positive

Select appropriate size nosepiece

Computing the Ratio of Computing the Ratio of Nitrous Oxide to OxygenNitrous Oxide to Oxygen

Add liters of nitrous oxide with the liters of oxygen (example 2+6=8)

Take the total of liters in use and divide into the liters of nitrous oxide (example 8/2=.25 or 25%)

Subtract the percentage of nitrous oxide from 100 to find the ratio of oxygen (example 100-25=75 or 75%)

During the Administration of During the Administration of Nitrous Oxide/OxygenNitrous Oxide/Oxygen

Begin the flow of oxygen at 8 liters Place the nosepiece over the patient’s nose

allowing breathing adjustment time Begin the nitrous oxide at 20% concentration and

oxygen at 80% Observe the patient for one minute prior to

changing dosage Increase nitrous oxide by ½ liter and decrease the

oxygen by1/2 liter until desired effect is obtained

Monitor clinical manifestations closely adjusting levels as needed after waiting one minute

NEVER LEAVE PATIENT UNATTENDED

Oxygenate patient until normalcy is regained (minimum 3 to 5 minutes)

Special NoteSpecial Note

If patients become irritated or they can no longer cooperate and their mouth tends to close, plane three is being approached. This is an indication that the nitrous oxide level is too high. Also, changes in physical symptoms, such as dilation of pupils or nausea, would be an indication of too much nitrous oxide. At this point the clinician should take three steps to rectify the situation.

1. Reduce the level of nitrous oxide or turn it off depending upon severity of the side effect or reaction;

2. Increase the level of oxygen;

3. Reassure the patient.

Legal Chart EntriesLegal Chart Entries

Patient’s vital signs (pre and post-op) Consent of the patient was granted Routine information including the date, procedure

performed, and information given to the patient Maximum levels of nitrous oxide and oxygen

stated in the terms of percentages of each gas administered and total volume used

Length of administrationAny other anesthetics, premedication, or

post medication administeredLength of oxygenation and patient’s report

of feeling normal prior to dismissalAny side effects or complication incurred,

or the fact that none occurred

LiabilityLiability

The dentist, dental hygienist and/or assistant can be held liable in any civil or malpractice suits filed by the patient.

An operator who releases a patient who has not regained normalcy can be held legally liable for any harm that results.

Clinical Findings During Clinical Findings During MaintenanceMaintenance

Reduced activity of the eyes means good sedation.

Increased activity of the eyes usually means sedation is too light.

Fixed, hard stare of the eyes means sedation is too deep and the ratio needs to be decreased.

Arms and legs crossed means the patient is not relaxed yet and needs more nitrous oxide.

Patient talks too much the sedation is too light due to mouth breathing, do not increase just try and get patient to stop talking.

Patient answers rapidly sedation is too light increase nitrous oxide or adjust nosepiece.

Patient answers slowly and deliberately having good sedation.

Patient does not answer may be tired and asleep or too deep, arouse patient and check verbally.

Perspiration appears on the face reassure the patient that this is expected and will pass.

Paraesthesia of extremities indicated early phase of Stage 1 reassure patient that this is “just as it should be”.

Paraesthesia of lips, tongue, or oral tissues indicates a more profound depth and permits injections of local anesthetic to be given comfortably.

Terms Related to Breathing Terms Related to Breathing and/or Respiration and/or Respiration

Eupnea – normal breathingTachypnea – rapid breathingBradypnea – slow breathingHyperpnea – over respirationHypopnea – under respirationAnoxia – total lack of oxygenHypoxia – decreased oxygen in the tissue

Vital SignsVital Signs

Normal respirations for an adult patient is 60 to 100 beats/minute

Normal respirations for a child patient is 80 to 120 beats/minute.

Normal blood pressure is approximately 120/80; however, systolic pressure less than 140 and diastolic pressure less than 90 is acceptable for an average adult patient.

Normal respiratory rate for an adult is 16 to 18 breaths per minute.

Normal respirations of a child will be 40 to 45 breaths per minute.

Occupational ExposureOccupational Exposure

Preventative measures should be taken in the dental office to minimize exposure. Primary control measures include:

1. Testing equipment for leakage & providing preventative maintenance 4 times/year.

2. Low leakage techniques – proper fitting nosepiece; closed air valve on nosepiece or preferably use of scavenging nose hood; minimize patient conversation.

3. Manufactured devices for collection and disposal of gases: scavenging masks & outdoor ventilation system.

4. Air monitoring program.