Nitrousoxide as a conscious sedative in minor oral surgical procedure

Abstract

Nitrous oxide (N₂O) is the most commonly used inhalation anesthetic in dentistry and is commonly used in emergency centers and ambulatory surgery centers as well. When used alone, it is incapable of producing general anesthesia reliably. However, as a single agent, it has an impressive safety and is excellent for providing minimal and moderate sedation for apprehensive minor oral surgical procedure. In this article, action of N₂O in overcoming the anxiety and pain of the patient during the minor oral surgery and its advantages and disadvantages, have been reviewed.

Nitrous oxide (N₂O) has been available since the mid-1800s but only gained general acceptance as dental inhalation sedation in the second half of the 20^th century. Its use accelerated in the 1970s and 1980s, leveled off for a brief period because of environmental concerns, and then continued to increase into the 21^st century. The purposes of this article are to: Review the indications and contraindications and importance of N₂O in minor oral surgical procedures.

What is Nitrous Oxide?

Nitrous oxide is a colorless and virtually odorless gas with a faint, sweet smell. It is an effective analgesic/anxiolytic agent causing central nervous system depression and euphoria with little effect on the respiratory system.[1]

Nitrous Oxide in Oral Surgery

Patient anxiety has always been a major issue in dental offices. This course reviews guidelines for use of N₂O for the dental practitioner and dental staff to manage anxiety and pain.

Dentists have expertise in providing anxiety and pain control for their patients. Although anxiety and pain can be modified by psychological techniques, in many instances pharmacological approaches are required.[2] Analgesia/anxiolysis is defined as diminution or elimination of pain and anxiety in a conscious patient.[3] The patient responds normally to verbal commands. All vital signs are stable, there is no significant risk of losing pro-tective reflexes, and the patient is able to return to preprocedure mobility. In children, analgesia/anxiolysis may expedite the delivery of procedures that are not particularly uncomfortable, but require that the patient not move.[3] It also may allow the patient to tolerate unpleasant procedures by reducing or relieving anxiety, discomfort, or pain. The outcome of pharmacological approaches is variable and depends upon each patient's response to various drugs. The clinical effect of nitrous oxide/oxygen inhalation, however, is more predictable among the majority of the population.

Preinstructions

• The patient should be advised to avoid the heavy meal prior to the use

• The patient is requested to void if necessary, prior to treatment

• Patients with contact lenses should be removed as gas leaks around the bridge of the nose may produce drying of the eyes.

Techniques of Administration

Nitrous oxide – oxygen sedation will always begin and end with the patient receiving 100% oxygen. Then, slowly allowed to breathe. A flow rate of 5–6 L/min generally is acceptable to most patients. The flow rate can be adjusted after observation of the reservoir bag. The bag should pulsate gently with each breath and should not be either over or underinflated. Introduction of 100% oxygen for 1–2 min, followed by titration of N₂O in 10% intervals is recommended. During nitrous oxide/oxygen analgesia/anxiolysis, the concentration of N₂O should not routinely exceed 50%. Increasing amounts of N₂O until the desired effect is achieved. It is important that the patient be reminded to breathe through the nose in order for the gas to work. The patient should be questioned as to how they are feeling to ensure an optimal level of nitrous is being administered. Therapeutic levels will vary from patient to patient. If the nitrous level being administered is too low, the patient will not be receiving an effective anxiolytic dose. If the nitrous level is too high, unwanted side-effects may occur.

Studies[4,5] have shown that children desaturate more rapidly than adolescents, and administering 100% oxygen to the patient for 3–5 min once the nitrous oxide in a closed system has been terminated is important.[4]

The objectives of nitrous oxide/oxygen inhalation include

• Reduce or eliminate anxiety

• Reduce untoward movement and reaction to dental treatment

• Enhance communication and patient cooperation

• Raise the pain reaction threshold

• Increase tolerance for longer appointments

• Aid in treatment of the mentally/physically disabled or medically compromised patient

• Reduce gagging

• Potentiate the effect of sedatives.

Indications

• A fearful, anxious, or obstreperous patient

• Certain patients with special health care needs

• A patient whose gag reflex interferes with dental care

• A patient for whom profound local anesthesia cannot be obtained

• A cooperative child is undergoing a lengthy dental procedure.

Contraindications

• Chronic obstructive pulmonary diseases

• Severe emotional disturbances or drug-related dependencies[6]

• First trimester of pregnancy[7]

• Treatment with bleomycin sulfate[8]

• Methylenetetrahydrofolate reductase deficiency.[9]

Whenever possible, appropriate medical specialists should be consulted before administering analgesic/anxiolytic agents to patients with significant underlying medical conditions (e.g. severe obstructive pulmonary disease, congestive heart failure, sickle cell disease,[10] acute otitis media, recent tympanic membrane graft,[11] acute severe head injury[12]).

Advantages

• Easy to administer

• Onset of action is rapid

• N₂O has bland, pleasant, nonirritating order

• Rapid uptake and elimination of N₂O ensures that no hangover effect is experienced

• Recovery is fast

• Titration is possible

• There is a wide margin of safety

• There is cardio-respiratory stability

• Nausea and vomiting are uncommon

• Reflex integrity is maintained

• No preparation of patient is required

• No need for any escort.

Disadvantage

• Equipment is expensive

• Patient must be able to breathe through the nose

• Interference of the nasal hood with injection to anterior maxillary region.

Conclusion

Nitrous oxide/oxygen anesthesia is used in a standard way in dentistry and medicine. And a review of the standards on a regular basis is invaluable to maintain the highest standard of care. Professional use and administration of N₂O is a tried and true method to managing patients’ anxiety for dental procedures. The overall patient experience is enhanced by careful and professional use of this practice-building anesthetic gas. Dental team members must adhere to the best clinical protocols and know the standard of care to ensure absolute safety for the patient and to minimize exposure to themselves. N₂O is safe and effective for use by qualified dental professionals in a wide variety of situations requiring pain and anxiety management in the minor oral surgical procedures.