Aiding In The Administration of Nitrous Oxide/Oxygen Analgesia Idaho State Board of Dentistry Expanded Function Fall 2002
Background 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 Dentistry 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 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 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 Effects Nausea is the most common side effect. It’s 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 Reactions Hypoxia Bone Marrow Depression Pressure/Volume Effect Psychologic Reactions Fire Protective Reflexes
Average Effects of Nitrous Oxide/Oxygen with Various 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 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 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 Plane 1 Patient appears normal, relaxed, and awake Patient my feel slight tingling in toes, fingers, tongue, or lips Patient my giggle Vital signs remain normal There are no definite clinical manifestations
Analgesia: Clinical Effects Plane 2 Patient may have a dreamy look Reactions of patient are slowed Partial amnesia may occur Voice will sound “throaty” Patient will feel warm and drowsy Patient may drift in and out of environment
Patient may hear pleasant ringing in ears Vital signs remain normal Pain is reduced or eliminated but touch and pressure is still perceived Patient is less aware of surroundings; sounds and smells are dulled
Analgesia: Clinical Effects Plane 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 Use Fear and anxiety Patient who refuses or is allergic to local anesthesia Prominent gag reflex Patient who gets impatient at long appointments
Indications with Special Considerations Cardiovascular disease Cerebrovascular disease Respiratory disease: asthma Hepatic (liver) disease Epilepsy and other seizure disorders Patients taking tranquilizers, analgesics, antidepressants or hypnotics
Contraindications of Use Nasal obstructions – common cold, upper respiratory infections, allergies, or deviated nasal septum Chronic Obstructive Pulmonary Disease Debilitating cardiac or cerebrovascular disease Pregnancy
Patients with psychiatric disorders or compulsive personalities Claustrophobic patients Children with severe behavioral problems The patient who does not want nitrous oxide/oxygen
Equipment Nitrous oxide tank – always blue Oxygen tank – always green Nitrous oxide/oxygen machine Breathing apparatus – Full face mask – Nasal hood – Nasal cannula
Equipment 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 of Nitrous Oxide/Oxygen Have patient visit the restroom Complete thorough medical history Take and record vital signs of patient ALWAYS BE POSITIVE when discussing techniques and effects, be honest but positive Select appropriate size nosepiece
Computing the Ratio of Nitrous 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 Nitrous 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 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 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 administration Any other anesthetics, premedication, or post medication administered Length of oxygenation and patient’s report of feeling normal prior to dismissal Any side effects or complication incurred, or the fact that none occurred
Aid in the Administration of Nitrous Oxide/Oxygen This is interpreted to mean that dental assistants can monitor the patient and adjust levels of nitrous oxide to lower concentrations after nitrous oxide/oxygen analgesia has been administered by a licensed dentist. Dental assistants are NOT certified to legally administer nitrous oxide to patients or to begin induction.
Liability 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 Maintenance 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 and/or Respiration Eupnea – normal breathing Tachypnea – rapid breathing Bradypnea – slow breathing Hyperpnea – over respiration Hypopnea – under respiration Anoxia – total lack of oxygen Hypoxia – decreased oxygen in the tissue
Vital 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 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.