chapter 18 Practical Considerations
In previous chapters of this section, the technique of administration, complications, and current concerns associated with inhalation sedation have been discussed. In this chapter, a number of additional factors are discussed in an attempt to reflect on and evaluate other factors that are important in the completeness of the overall training of the administrator of nitrous oxide-oxygen (N2O-O2). Many of these questions do not usually arise until the clinician has been using inhalation sedation for awhile. It should be remembered that realistically, complications of N2O-O2 sedation are indeed rare, and N2O is a very safe agent for use in the health sciences.
One of the most important factors to consider when using inhalation sedation is that the gases have a very rapid onset of action. Because of this rapid onset, it becomes possible for patients to be titrated to a precise level of sedation. The ability to titrate with inhalation sedation is of considerable importance because it is quite possible that a patient may require different concentrations of N2O-O2 to achieve the same level of sedation at subsequent visits. The absence of titration leads to increased patient reports of negative reactions to N2O-O2, and clinicians begin to shy away from its use. Titration is the only means for the administrator to satisfactorily determine the appropriate level of sedation. Factors that may influence the concentration of N2O-O2 necessary for adequate sedation include the patient’s level of anxiety, expected level of pain, age, and presence of other sedatives or CNS depressants.
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.
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.
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.