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Outline

Nitrous Oxide Sedation in Pediatric Dentistry

Major Talking Points Definitions and Background Effects of N2O Technique Complications/Precautions Effects on Systems Controlling N2O in the Operatory

Definitions and Background

Definition: Conscious Sedation

Why Conscious Sedation? 20% having high fear of dentistry 2/3 of these acquired in early childhood (Milgrom, JADA, 1988) 25% of adults - fear of injections (Milgrom, JADA, 1997) 30% somewhat or very nervous, or terrified of going to the dentist (45 million) (Dionne, JADA, February 1998) 23 million willing to go to the dentist if GA and CS more readily available.

History of N2O 1793 - Joseph Priestly invented N2O Initially used as an anesthetic agent in 1844.

N2O is Common

Effects of N2O

Purpose of Nitrous Oxide Sedation Reduce fear, apprehension, or anxiety Raise pain reaction threshold Reduce fatigue

Fear Reduction & N2O One group treated with behavior management only; other group with behavior management and N2O. Dental treatment of highly fearful children is carried out more successfully with N2O during the first few sessions. N2O is thus a valuable aid for making highly fearful children treatable quickly.

Fear Reduction & N2O When highly anxious children are treated with nitrous oxide for a number of consecutive sessions, their anxiety remains significantly lower during a following control period, even without use of nitrous oxide.

Fear Reduction and N2O

Increase Pain Reaction Threshold

Four Stages of Anesthesia Analgesia patient is conscious reflexes are intact Delerium Surgical Anesthesia Respiratory Paralysis

Analgesia In analgesia stage, the patient is conscious, has all vital reflexes intact, can communicate and cooperate with the dentist, and quickly returns to a normal state following a few minutes of oxygenation.

Four Plateaus of Analgesia Paresthesia - tingling of hands, feet Vasomotor - warm sensations Drift - euphoria, pupils centrally fixed, sensation of floating Dream - eyes closed but will open in response to questions, difficulty in speaking, jaw sags open

N2O Should Be Used To: Ease fears and anxieties Aid in the treatment of special patients Increase tolerance for longer appointments Raise the pain reaction threshold

N2O Should Not Be Used To: Control defiant or uncontrolled behavior Control pain by replacing local anesthesia Replace poor techniques of behavior management

GA vs. N2O

N2O vs. # of Visits The purpose of the present study was to measure feelings of pleasure by children who were undergoing dental treatment under nitrous oxide therapy during consecutive treatment sessions, and at a six-month follow-up visit. Fifty-two children between the ages of 3 and 5 years (mean age 4.3 +/- 1.06) children, who required two or more operative treatment visits participated in the study. It is concluded that the sense of pleasure is strengthened through the second visit, but that the sense of pleasure and ability to cope is overwhelmed by the inconvenience of the dental treatment at the third visit.

Uptake and Saturation of N2O

Signs of Saturation Reminding child continuously to hold mouth open No response to questions Agitation Sweating Nausea Unconsciousness

Reduce N2O Dosage... with lengthy administration (> 30 min.).

Elimination of N2O Rapid Primarily through the lungs Small amount through skin, sweat glands, urine, and intestinal gas

Diffusion Hypoxia High outpouring of N2O Dilutes available oxygen in lungs

Technique

Nebraska Inhalation Analgesia Permits Portable oxygen tank Delivery system that delivers a maximum of 80% N2O Medical history Physical evaluation ("...vital signs such as pulse, blood pressure, respirations, temperature and weight..." Oral pharyngeal airways available Emergency drugs

Preparation of Patient Patient in reclined position Use TSD Describe sensations in advance

ASA Classifications ASA I - A normal healthy patient. (ASA = American Society of Anesthesiologists) ASA II - A patient with mild systemic disease. ASA III - A patient with severe systemic disease. ASA IV - A patient with severe systemic disease that is a constant threat to life. ASA V - A moribund patient who is not expected to survive without the operation. ASA VI - A declared brain-dead patient whose organs are being removed for donor purposes. E - Emergency operation of any variety (used to modify one of the above classifications, i.e., ASA III-E).

Administration of N2O Medical history & vital signs 5 - 6 liters O2 Increase N2O gradually; watch for stages of analgesia Maintenance about 20 - 40% Reduce N2O with long procedures Record N2O levels in the chart 3 - 5 minute O2 flush Rapid induction (surge) technique

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Administration of N2O

Complications/Precautions

Complications/Precautions Vomiting - due to: overdosage prolonged administration pre-existing GI infection, influenza history of motion sickness or vomiting (use anti-emetic) impurities in the delivery system (rare) If vomiting occurs, turn patient to the side and use HVE Prevent vomiting by close observation of patient

Hallucinations Complications/Precautions

Asthma and N2O Estimated 40% of asthmatic attacks are psychologically induced (Bennet, 1984) Clinically significant decrease in lung function in 15% of pediatric patients but couldn’t predict who would have this decrease (Mathew, JADA, Aug 1998)

Complications/Precautions Mild rhinitis or colds are not absolute contraindications Contraindicated in patients with a depressed respiratory system chronic emphysema tuberculosis multiple sclerosis remember, N2O will potentiate drugs that depress the respiratory system

Complications/Precautions Contraindicated in patients with blocked eustachian tube, pneumothorax, pneumoperitoneum, and pneumopericardium Contraindicated in the first trimester of pregnancy

Complications/Precautions Other possible contraindications: severe cardiac disease hyperthyroidism uncontrolled diabetes sickle cell anemia severe asthmatic conditions

Effects on Systems

Effects on Systems CNS - primary system effected by N2O Respiratory respiratory rate increase decrease tidal volume N2O potentiates respiratory depression with concommitant use of narcotics, barbiturates, or other sedatives

Effects on Systems Cardiovascular normally, no meaningful changes in heart rate or pressure myocardial depression with cardiac decompensation (congestive heart failure) patients with ischemic  heart disease without decompensation may benefit from N2O

Myocardial Depression in CHF Patients

Chronic Exposure to N2O

Chronic Exposure Disorders Reproductive Hematologic Immunological Neurological Liver Kidney

Neurological Symptoms of Chronic Exposure Loss of concentration Numbness and paresthesia Ataxia Loss of bowel sphincter control Loss of bladder control Impotence

Fetal Effects 1967 (Vaisman) - report showing increased incidence of spontaneous abortion among female Russian anesthesiologists 1980 (Cohen, et al) - report showing increased spontaneous abortion rates (2.3) for DAs and unexposed wives of DDSs who used N2O in their practices; also higher rates of liver, kidney and neurological disease 1992 (Rowland, et al.) - demonstrated reduced fertility among female DAs exposed to ambient levels of unscavenged N2O for longer than five hours per week; the concentration and length of exposure that produce any of these effects remain undocumented.

Controlling N2O in the Operatory

N2O Timeline 1977 - the National Institute of Occupational Safety and Health issued an Alert, cautioning health professionals not to exceed the agency's recommended exposure level of 25 parts per million. July 1980 - JADA, Ellis Cohen, M.D., published a study titled "Occupational Disease in Dentistry and Chronic Exposure to Trace Anesthetic Gases." 1980 - the ADA Council on Dental Materials, Instruments and Equipment recommended that dentists equip their offices with scavenging systems. 1994 - NIOSH reiterated its cautionary that exposure to nitrous oxide be limited to 25 ppm. 1995 - CSA convened an expert panel to review the scientific literature on nitrous oxide and determine what might be an appropriate, or safe, level. While the group never reached a consensus, they did agree that the NIOSH recommendation appeared unreasonably low. The panel then issued its recommendations, published in 1997, for minimizing exposure in the dental office.

ADA - Working with N2O In 1997, the ADA councils on Scientific Affairs and Dental Practice brought together a panel of researchers and asked them how dentists might best control nitrous oxide concentrations in their offices. After studying the scientific literature on nitrous oxide, the panelists issued 11 recommendations:

ADA: 11 Recommendations The dental office should have a properly installed nitrous oxide delivery system. This includes appropriate scavenging equipment with a readily visible and accurate flow meter (or equivalent measuring device), a vacuum pump with the capacity for up to 45 liters of air per minute per workstation, and a variety of sizes of masks to ensure proper fit for individual patients. The vacuum exhaust and ventilation exhaust should be vented to the outside (for example, through the vacuum system) and not in close proximity to fresh-air intake vents. The general ventilation should provide good room air mixing.

ADA: 11 Recommendations Each time the nitrous oxide machine is first turned on and every time a gas cylinder is changed, the pressure connections should be tested for leaks. High-pressure line connections should be tested for leaks on a quarterly basis. A soap solution can be used for testing. Or, alternatively, a portable infrared spectrophotometer can be used to diagnose an insidious leak. Prior to first daily use, all nitrous oxide equipment (reservoir bag, tubings, mask, connectors) should be inspected for worn parts, cracks, holes or tears. Replace as necessary. The mask may then be connected to the tubing and the vacuum pump turned on. All appropriate flow rates (that is, up to 45 L/min. or per manufacturer's recommendations) should be verified.

ADA: 11 Recommendations A properly sized mask should be selected and placed on the patient — and a good comfortable fit ensured. The reservoir (breathing) bag should not be over- or underinflated while the patient is breathing oxygen (before administering nitrous oxide). The patient should be encouraged to minimize talking and breathing through his or her mouth while the mask is in place. During administration, the reservoir bag should be periodically inspected for changes in tidal volume and the vacuum flow rate should be verified.

ADA: 11 Recommendations Upon completing administration, 100 percent oxygen should be delivered to the patient for five minutes before removing the mask. In this way, both the patient and the system will be purged of residual nitrous oxide. Do not use oxygen flush. Periodic (semiannual interval is suggested) personal sampling of dental personnel, with emphasis to chairside personnel exposed to nitrous oxide, should be conducted (for example, use of diffusive sampler [dosimeters] or infrared spectrophotometer).

Levels of N2O

Levels of N2O

Controlling N2O in the Operatory Engineering controls Inspection equipment for wear, cracks, tears test connections Scavenging system no system currently accepted by ADA flow rate of 45 L/min vacuum rate

Controlling N2O in the Operatory Ventilation Fresh air inlets - ceiling Return air vents - floor level Location of ventilation system exhaust Air exchange rate (>10/hr)

N2O Scavenging Factors of scavenging effectiveness auxilliary evacuation rate of evacuation of scavenging device operatory ventilation use of air sweep fans reduced concentration of delivered N2O poor patient behavior certain procedures (local anesthesia) improper administration loose connections

N2O Scavenging - Device

Scavenging - Nasal Hood

Scavenging Vacuum

See Ya Next Time….