Bispectral Index and Clinical Parameters Evaluation in Dental Procedures
Condition: Anxiety; Pain
Study type: Interventional
Phase: Phase 4

Summary: 
      BACKGROUND: The degree of consciousness during nitrous oxide use is still a matter of concern
      for both dentists and anesthesiologists. Investigators hypothesized that BIS levels do not
      vary according nitrous oxide concentration during minimum to moderate sedation in the dental
      treatment.

      METHODS: One hundred patients undergoing dental procedures demanding local anesthesia (1.8 mL
      of 2% lidocaine with 1:100.000 epinephrine) were enrolled in this study. Initial pain and
      anxiety were measured by 11-point numerical and anxiety visual scales, respectively.
      Systolic/diastolic arterial blood pressure, SpO2, heart and respiratory rates, and
      psychomotor ability (Trieger test) were assessed before, during and after dental treatment.
      Sedation levels were evaluated by both BIS and sedation analogic scale at the same intervals.
      The duration of treatment along with nitrous oxide concentration and side effects were
      observed. Kruskal-Wallis, Friedman and Mann-Whitney tests were used (alpha=5%).
    

Detailed description: 
      One-hundred ASA I / II volunteers of both genders were selected in different dental
      speciality clinics (restorative dentistry, endodontics, implantology, and oral surgery) of
      Dental Institute of Pontifical Catholic University of Rio de Janeiro PUC-Rio).

      After anamnesis and obtaining written informed consent, all volunteers were asked to fill an
      11-point numerical scale in order to quantify the initial pain. The scale showed 0 as "no
      pain" and 10 as the "worst pain imaginable". In addition, volunteers were also asked to fill
      a facial image scale in order to determine the initial anxiety. This scale showed four
      levels: 0 corresponding to absolutely calm; 1 - slightly stressed; 2 - stressed; and 3 -
      extremely stressed.

      The volunteers were positioned in the dental chair and instructed to fill a Trieger test
      (psychomotor evaluation) during the following periods: 1) before sedation; 2) during the
      sedation (10 minutes after respiratory stabilization with N2O/O2); and 3) 10 minutes after
      the end of sedation. The number of wrong connected points (precision) and the time required
      to fill all points were used to estimate psychomotor ability.

      A pulse oxymeter was placed in the volunteers' thumb and an electronic sphygmomanometer was
      positioned in the forearm in order to evaluate oxygen saturation (SpO2), systolic and
      diastolic pressures, and hearth rate during the same moments of the Trieger test. Respiratory
      rate was evaluated at same moments, by direct observation of thoracic movements.

      The electrodes of BIS monitor were placed and the values were obtained at same operatory
      periods previously described, despite the continuous BIS monitoring. After BIS-signal
      stabilization, the dental procedure and the sedation with N2O/O2 were explained to the
      volunteer. Two previously calibrated operators installed BIS electrodes, applied the Trieger
      test and sedated all subjects. A third operator performed the dental treatments.

      Five minutes after reaching ideal sedation level, the anesthetic solution (1.8 mL of 2%
      lidocaine with 1:100.000 epinephrine) was injected. Right after the end of clinical
      procedure, 100% O2 were provided during 5 minutes and a new Trieger test was filled out. The
      volunteer was dismissed if this last Trieger test was compatible with the first one. At this
      moment, they were also asked about discomfort or complications. The duration and type of
      dental procedure were also registered.

      The N2O/O2 equipment was composed by two flow meters with an anti-hypoxia system valve, 70%
      N2O maximum disposal and 30 L/min O2 valve to immediate oxygen dispensation. Masks were
      individually selected, being 100% O2 (6 L/min) dispensed until respiratory rate
      stabilization. N2O was incremented at 10% each 2 minutes (70% max, if necessary) until some
      of the following signals were noticed: silence, relax/comfort report, decreased eyelid
      movements, decreased spontaneous body movements, warm sensation, tingling sensation or
      numbness at feet, hands or oral region, and slightly euphoric sensation. The dental procedure
      started after 5 min from the ideal sedation achievement.

      The sedation level was scored by using the five-points Observer's Assessment of
      Alertness/Sedation (OAA/S) scale, previously described elsewhere. In addition, BIS was used
      to monitoring brain cortical activity at 0.5 to 30 Hz frequency bandwidth, checking impedance
      before every reading. Impedance remained below 800 ohms. Zipprep-type electrodes were placed
      according to manufacturer instructions. Fp1-Fpz was monitored in channel 1, Fp2-Fpz in
      channel 2 and the ground reference was placed on the pre-auricular region. BIS and both BIS
      channel waves were recorded from successive 2 seconds periods 13 and updated at every 5
      seconds. The automatic artifact detection and rejection system of the BIS monitor were used.
      Baseline levels were obtained before sedation.

      Results were submitted to Kruskal-Wallis' (Dunn), Friedman's, Mann-Whitney's and Spearman's
      correlation tests. The significance level was set at 5%. The analysis was performed by using
      BioEstat 5.0.
    

Intervention name(s): Nitrous Oxide
Intervention type(s): Drug
Intervention description(s): The N2O/O2 equipment was composed by two flow meters with an anti-hypoxia system valve, 70% N2O maximum disposal and 30 L/min O2 valve to immediate oxygen dispensation. Masks were individually selected, being 100% O2 (6 L/min) dispensed until respiratory rate stabilization. N2O was incremented at 10% each 2 minutes (70% max, if necessary) until some of the following signals were noticed: silence, relax/comfort report, decreased eyelid movements, decreased spontaneous body movements, warm sensation, tingling sensation or numbness at feet, hands or oral region, and slightly euphoric sensation.
Other intervention name(s): Nitrous oxide / oxygen
Intervention MeSH terms: Nitrous Oxide
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: nitrous oxide; conscious sedation; pain; anxiety