1 | Sedative Medications in Dentistry
Minimal sedation can be achieved with a low-dose oral sedative or nitrous oxide-oxygen inhalation sedation. Nitrous oxide is considered to be a weak anesthetic agent; it is removed from the blood stream via the lungs unchanged, which means that in experienced hands, nitrous oxide is safely administered and the risk of rendering the patient unconscious is small. Nitrous oxide produces relatively weak sedation; as such, it is not recommended for severely anxious or phobic patients.
Doses of nitrous oxide are titrated at 5% increments over 3 to 5 minute intervals; levels up to a maximum of 70% should be sufficient to achieve mild or moderate sedation. Toward the end of the procedure the clinician must titrate nitrous oxide levels down and oxygen levels up until oxygen is administered at 100% for at least five minutes as this decreases the risk for diffusion hypoxia and sudden unconsciousness; at this stage complete recovery ensues and the patient can be discharged in the care of a companion. Patients should be instructed to refrain from having food six hours prior to their appointment as eating increases the risk of emesis during nitrous oxide sedation. As with all sedation techniques, patient consent is required for nitrous sedation.
Nitrous oxide is contraindicated in pregnancy, respiratory infections, chronic obstructive pulmonary disease (COPD), sinus infections, tuberculosis, blocked nasal passages and eustachian tubes, multiple sclerosis and congestive heart failure.
Minimal and moderate sedation can be achieved with oral sedation, which involves the oral administration of a sedative agent, the absorption of which occurs in the gastrointestinal tract. The sedative agent is administered as a premedication, usually one hour prior to the appointment and the night before the appointment. In most cases, sedation that ensues is mild to moderate. Relative to other sedation methods including inhalation and intravenous sedation, oral sedation has a slower onset of action.
In the past, clinicians have prescribed antihistamines for anxiety control. However, the current preferred method for oral sedation in dental practice seems to be BZDs, which are psychoactive drugs with anxiolytic, sedative and hypnotic effects. BZDs used in dental practice include alprazolam, clonazepam, diazepam, lorazepam, midazolam, oxazepam and triazolam (Table 1).
Combining nitrous oxide inhalation sedation with higher doses of sedative medication such as BZDs produces moderate and possibly deep sedation; this combination carries a higher risk of respiratory depression. If the clinician chooses this combination, a higher level of patient monitoring is recommended.
For titration guidelines of sedative medication, refer to the “2016 ADA Guidelines for the Use of Sedation and General Anesthesia by Dentists.” (see Suggested Reading List on page 48).
2 | Medical Considerations Before Prescribing Benzodiazepines
Prescribing BZDs for anxiety control commands the medical considerations in various patient groups. Refer to Table 2 on page 46.
3 | Pre-Discharge Assessment of Sedation
Following the procedure, the clinician must determine discharge readiness based on the discharge criteria as outlined in the “2016 ADA Guidelines for the Use of Sedation and General Anesthesia by Dentists” (see Suggested Reading List). The half-life of the sedative used must be considered when assessing patients for discharge readiness.
In order to be deemed ready for discharge, patients need to meet the following criteria:
• vital signs within normal limits
• absence of vertigo, nausea and vomiting
• alertness: must be able to state own name, date of birth, address
• orientation to the time, date and place and pre-sedation condition
• ambulation with minimal or no assistance
• presence of a responsible escort who will transport the patient home
• ability to stand unassisted with closed eyes
The time of discharge and the status of the patient at discharge must be documented.
Post-operative instructions must include no alcohol, driving or operating machinery for at least 24 hours following sedation or longer if persistent sedation or drowsiness are experienced.
* Do NOT prescribe BZDs in patients taking the following: alcohol, anti-depressants, and opioids. Also, see the drug monograph at the end of the chapter for more information.