One of Dr. Gillman’s concerns was that the dentist based the initial nitrous oxide concentration solely on a patient’s alcohol consumption. There was another criterion, too, and that was a patient’s desire to be "in control." A person who was uncomfortable about not being in control was started out at a lower concentration.
Regardless of what concentration was used at the start, the dentist (L.G.) queried each patient five minutes after the patient inhaled the nitrous oxide/oxygen mixture to see how she or he was feeling. Based on the answers given, the dentist adjusted (that is, titrated) the nitrous oxide concentration to achieve a comfort level satisfactory to the patient. As we stated in the article, "sometimes the dentist increased or decreased the nitrous oxide concentration during the procedure, based on his assessment of the comfort level of the patient." The patient’s alcohol consumption was not a criterion at that point.
A second concern raised by Dr. Gillman is that the dentist may have been using a machine lacking "built-in fail-safe devices" so that either hypoxia or anesthesia might have occurred with our patients. We used a Porter Analgesia Flowmeter Model MXR-1 (Porter Instrument Company Inc., Hatfield, Pa.) nitrous oxide-oxygen delivery system, with built-in fail-safe devices.
We erred in the article when we said the maximum amount of nitrous oxide that could be delivered was 60 percent; in point of fact it was 65 percent. Dr. Graham, as a matter of course, does not use nitrous oxide concentrations higher than 50 percent to avoid the risks of anesthesia.
