Fig. 4.7 The 'mouth open' sign.
4.11.5 Subjective symptoms
Subjective symptoms experienced by the patient are (Fig. 4.8):
(1) mental and physical relaxation;
(2) a tingling sensation (paraesthesia) singly or in any combination of lips, fingers,
toes, or over the whole body;
(3) mild intoxication and euphoria;
(4) lethargy;
(5) a sense of detachment, sometimes interpreted as a floating or drifting sensation;
(6) a feeling of warmth;
(7) indifference to surroundings and the passage of time;
(8) dreaming;
(9) lessened awareness of pain.
If the patient tends to communicate less and less, and is allowing the mouth to close,
then these are signs that the patient is becoming too deeply sedated. The concentration
of nitrous oxide should be reduced by 10 or 15% to prevent the patient moving into a
state of total analgesia.