Pre-administration Preparations

Before proceeding with the administration of nitrous oxide/oxygen analgesia/anxiolysis, a preoperative assessment must be performed. The assessment consists of a medical history and measurement of the patient’s vital signs. The medical history provides information regarding the patient’s:

• Allergies and previous allergic or adverse drug reactions

• Current medications including dose time, route, and site of administration

• Diseases, disorders, or physical abnormalities and pregnancy status

• Previous hospitalizations including dates and reasons

Vital sign measurements include:

• Blood pressure

• Pulse

• Oxygen saturation (patients’ receiving greater than 50% nitrous oxide/oxygen concentration should be monitored)

• Respiratory rate

• Lungs - clear or congested

• Nasal airway – clear or obstructed, nasal or mouth breather. Nitrous oxide/oxygen is inhaled through the nose. Any obstructions or tendencies that interfere with nasal breathing will reduce the amount of gas reaching the lungs and ultimately the brain.

The use of nitrous oxide/oxygen analgesia/anxiolysis should be well documented. Before administration a written informed consent should be obtained from the parent or guardian. Pretreatment dietary precautions, if indicated, should be recorded. Unless the patient has a history of vomiting, there are no fasting requirements for patients. It is recommended patients be instructed not eat for two hours before nitrous oxide administration to minimize the possibility of vomiting and aspiration.

Additional information recorded in the chart includes:

• Reasons for recommendation of nitrous oxide/oxide analgesia/anxiolysis (poor behavior, anxiety, extensive treatment)

• The percent of nitrous oxide/oxygen ratio and the flow rate

• Duration of the procedure

• Duration of post-treatment oxygenation

• Status of patient upon discharge (active and alert, lethargic, accompanied by adult)

• Pulse oximeter readings – pulse rate, oxygen saturation (for concentrations greater than 50% nitrous oxide/oxygen)

• Clinical observations of the patient's reaction to nitrous oxide/oxygen analgesia/anxiolysis:

• • Response to commands

  • Skin color

  • Respiratory rate and rhythm

  • Musculo-skeletal changes

  • Behavior

Table 1 and Table 2 provide a summary of characteristic patient responses to nitrous oxide/oxygen analgesia/anxiolysis.

Stages / levels of consciousness

There are three states or levels of consciousness during nitrous oxide/oxygen administration.

The first level is the Active Alert Consciousness or Induction stage. The patient is beginning to experience the sensations felt during the initial administration of nitrous oxide/oxygen analgesia. This is an introductory or preoperative stage and the patient is not ready to undergo treatment.

The second level is the Altered State of Consciousness or Maintenance stage. The patient is correctly titrated and is receiving the ideal concentration of nitrous oxide/oxygen. This is the stage the patient is most comfortable. Once the patient describes the body and sensory responses associated with this level, treatment may commence.

The third level is the Loss of Consciousness stage. In this stage the nitrous oxide/oxygen concentration administered to the patient is too high and the patient expresses discomfort verbally and through bodily responses. If the patent exhibits these responses, treatment is stopped, the concentration of the nitrous oxide/oxygen concentration reduced and the patient is instructed to breathe though the mouth, to enhance nitrous oxide/oxygen by dilution with room air. Once the patient elicits positive responses again, treatment is continued at the reduced nitrous oxide/oxygen level.