Procedural Anxiety

As the patient’s anxiety decreases and the bulk of discomfort associated with the procedure is complete, the percentage of N₂O necessary to achieve a given level of sedation will correspondingly decrease, with all other variables remaining equal. With proper patient management by both the administering clinician and ancillary staff, a fearful patient should become less apprehensive about subsequent procedures. If the patient is titrated carefully to his or her “ideal sedation level,” it will likely be observed that the patient requires somewhat lower N₂O concentrations as he or she becomes progressively less anxious over time.

Although this is true for most patients and for most forms of procedural treatment, it is also possible that a patient who has been responding quite well at 30% N₂O will have an inadequate clinical effect from that concentration when a different type of procedure is undertaken. For example, this patient may respond well at 30% N₂O for restorative treatment; however, when undergoing periodontal surgery, the patient may require 45% N₂O. This is explained by the increased level of anxiety produced in this patient by the prospect of a surgical procedure in contrast with the more benign (in this patient’s mind) restorative treatment.

Baseline Level of Stress

A significant influence on the level of N₂O required for sedation is the patient’s baseline level of stress. The patient’s state of mind has a significant bearing on the manner in which central nervous system (CNS)-depressant drugs act. A patient may arrive at the facility on a day when things have just not gone well. If this patient has any degree of procedural anxiety, it becomes obvious that our sedation technique has a formidable task ahead. Contrast this with the same patient who arrives at the facility having had a simply wonderful day. The concentration of N₂O required to sedate this patient will probably be lower than that required in the first situation.

It is impossible, and indeed foolhardy, to discount the influence of outside stresses on the patient. All practicing clinicians have encountered remarkably different behavior patterns from the same patient at different visits. The process of titrating N₂O will help compensate for the effects of these outside influences.

As discussed in Chapter 4, it is recommended that the anxious patient and the medically compromised patient be scheduled for their procedure earlier in the day. At this time, presumably following a period of restful sleep, the medically compromised patient is rested and better able to tolerate any additional stresses imposed by the procedure. The fearful patient ought to be treated early in the day for the simple reason that the patient will want to get “it” over with as soon as possible. The procedural appointment might well be the most unpleasant part of this patient’s day. An appointment scheduled late in the day allows the patient more time to worry and for a level of anxiety to increase. Scheduled later in the day, this patient might require significantly greater levels of N₂O to achieve sedation than would have been necessary if he or she had been treated earlier in the morning.

Level of Fatigue

The level of baseline fatigue has an effect on the patient’s pain reaction threshold and therefore on the response to N₂O-O₂ sedation. Patients who are tired and unable to sleep the night before the appointment because of procedural fear overreact to most stimuli. With their “nerves on edge,” they interpret usually nonpainful stimuli as painful. N₂O-O₂ inhalation sedation may still prove to be effective; however, the patient may require greater concentrations of N₂O.

When a patient appears to be apprehensive about an upcoming treatment, it is prudent for a clinician to address this fact and consider prescribing a sedative-hypnotic for the patient 1 hour before bedtime the evening before the scheduled treatment. A well-rested patient may require lower concentrations of N₂O to achieve comparable levels of sedation than the overtired patient.

When the three factors mentioned are considered, it becomes obvious that the same person may respond to N₂O-O₂ in an entirely different manner at subsequent appointments. When titration is not used, it is entirely possible that the level of N₂O used at prior visits will produce either the same level of sedation, decreased levels of sedation, or overly deep sedation of the same patient. The use of titration at each and every appointment minimizes the significance of these factors.