Desirable Characteristics of N2O/O2 Sedation
Upon completion of this chapter, the reader should be able to:
1. Identify the analgesic properties of N2O/O2 sedation.
2. Identify the anxiolytic properties of N2O/O2 sedation.
3. Identify the amnestic effect when using N2O/O2 sedation.
4. Describe the onset of action.
5. Discuss the advantage of N2O/O2 sedation with regard to the ability to titrate the drug.
6. Identify the recovery process following N2O/O2 sedation.
7. Recognize the process of nitrous oxide elimination from the body.
8. Appreciate the well-documented acceptance of N2O/O2 sedation.
9. Recognize other methods of patient management that are combined with N2O and O2 and discuss the advantages and disadvantages of each.
The desirable characteristics of N2O/O2 sedation are many. Often, they provide an advantage over other pain and anxiety management options. There are few disadvantages. The pharmacokinetics of N2O support the numerous advantages for sedation (Box 4-1). Judge for yourself how the N2O/O2 option compares with others.
A. Analgesic Properties (Pain Control)
1. Chapman and colleagues1 state that a mixture of 20% N2O and 80% O2 has the same analgesic equipotence as 15 mg of morphine. Other articles verifying the analgesic efficacy of N2O have been reported.2–4
2. The level of pain control afforded by N2O can vary among patients because of individual biovariability; however, the analgesic properties of N2O are well recognized and its potency is significant.1 These analgesic properties are useful even with the severe pain associated with myocardial infarction.5 N2O has the ability to raise the patient’s pain threshold when administered before intraoral injections in dentistry.6
3. N2O/O2 is also advantageous when other analgesic drugs are contraindicated (e.g., allergy).
4. Fear affects an individual’s ability to tolerate pain; painful stimuli can be exaggerated in an anxious patient. A common fear is fear of an injection or a needle (e.g., vaccination), which can intensify an individual’s reaction to pain. N2O has the ability to manage both pain and fear.
B. Anxiolytic Properties (Sedative Effects)
1. Patient anxiety has long been associated with healthcare.7 A person’s mental ability to cope with certain situations can depend on such factors as age, gender, previous experiences, and personality characteristics.8
2. The literature continues to support N2O/O2 sedation as a modality that can significantly assist patients in handling their fear or anxiety by producing sedation or a sense of well-being. Sedation enables the patient to become calm, relaxed, and able to tolerate the situation better or with no difficulty. Jackson and Johnson concur that N2O/O2 sedation is an “excellent choice” for managing mild fear.9
a. This relaxed feeling has a positive effect on the patient’s pain threshold.
b. Mood changes with N2O have been studied. Zacny and colleagues10 report positive mood changes in patients with high anxiety and in those with low anxiety. Children older than 6 years were less distressed during nitrous oxide administration as reported by Kanagasundaram and colleagues.11
c. Patients with dental fear were treated with N2O/O2 sedation. Results were favorable; studies reassessed patients 1 and 5 years later. The results showed that the N2O treatment method still had a positive effect.12,13
3. In treatment of pediatric patients, N2O/O2 has been shown to facilitate positive behavior and lowered anxiety levels on sequential visits.14 It is a continuing goal of all healthcare providers to prevent negative early childhood experiences to reduce the number of fearful adults. Ultimately, the goal is to provide patients with enough positive experiences that they do not require N2O/O2 sedation in the future.
C. Amnestic Properties
1. The amnestic property of N2O/O2 sedation is another of its positive attributes.15 Postoperatively, patients often state they cannot recall the severity of their pain or anxiety or its duration.
2. The passage of time tends to become unclear or compressed under N2O/O2 sedation. A patient may remark how quickly time passed during a long procedure.6
D. Onset of Action
1. N2O/O2 sedation has a rapid onset of action.4 Because of the pharmacologic characteristics of N2O, clinical effects may begin in less than 30 seconds, with peak effects usually occurring in less than 5 minutes.
2. Another conscious-sedative modality that closely parallels the rapid onset of the clinical action of N2O/O2 is intravenous (IV) sedation.
1. Titration is the process of administering a drug incrementally to a specific level or endpoint of sedation. It allows for the exact amount of the drug necessary to be delivered to every patient at every appointment. Titration is very easily accomplished with N2O/O2 sedation. N2O is one of several drugs that accommodate the concept of titration well.16
2. Titration is also possible with IV sedation; however, in this case, reversal is not as straightforward as with N2O.