- The patient should breathe ambient air for a further 5 min before leaving the
dental chair. The patient should be allowed to recover for a total period of 15 min
before leaving.
At all times the patient must remain conscious. This is judged by the five clinically
discernible signs described previously.
The above method of administration is the basic technique that is required in the early
stages of clinical experience for any operator. This method ensures that the changes
experienced by the patient do not occur so quickly that the patient is unable to cope.
Once the operator has sufficient skill and confidence the stages can be 'concertinaed',
for example, by starting at 20% nitrous oxide and reducing the time intervals between
increments.
The initial time intervals of 60 s are used because clinical experience shows that
shorter intervals between increments can lead to too rapid an induction and over-
dosage.
4.11.3 The correct level of clinical sedation with nitrous oxide
One of the problems for the inexperienced clinician is to determine whether or not the
patient is adequately sedated for treatment to start. By careful attention to signs and
symptoms experienced by the patient the dentist will soon be able to decide whether
the patient is ready for treatment.
The very rapid uptake and elimination of nitrous oxide requires the operator to be
acutely vigilant so that the patient does not become sedated too rapidly.
4.11.4 Objective signs
The objective signs showing the patient is ready for treatment are (Fig. 4.6):
(1) the patient is awake;
(2) the patient is relaxed and comfortable;
(3) the patient responds coherently to verbal instructions;
(4) pulse rate is normal;
(5) blood pressure is normal;
(6) respiration is normal;
(7) skin colour is normal;
(8) pupils are normal and contract normally if a light is shone into them;
(9) the laryngeal reflex is normal;
(10) the gag reflex is reduced;
(11) reaction to painful stimuli is lessened;
(12) there is a general reduction in spontaneous movements;
(13) the mouth is maintained open on request (Fig. 4.7).