Capnography Monitoring During Intravenous Conscious Sedation Sedation With Midazolam for Oral Surgery
Condition: Hypoxemia
MeSH terms: Hypoxia
Study type: Interventional

Summary: 
      Dentists use sedation to help patients accept difficult procedures and to relieve anxiety.
      During sedation, the well-being of the patient is monitored by the dental team. When carried
      out according to recognised guidelines,intravenous dental sedation is considered to be very
      safe. For some patients, dental sedation is a useful alternative to general anaesthetic. It
      is cheaper and has the potential to be more accessible. Oximetry(measurement of oxygen
      status) is the current gold standard in dental sedation. The main risk to the patient during
      sedation is a slowing of breathing due to the effects of the sedative drug. Studies from
      other settings where sedation is practiced suggest that an additional monitor with
      capnography facilitates early detection of depressed breathing. However, the results of
      studies from other medical settings cannot be generalised to dental sedation, because of
      different techniques used and the types of patients. The depth of sedation may also be vary.
      For dental sedation, patients remain responsive at all times and breathe for themselves.
      Capnography gives breath by breath information using a simple device placed close to the nose
      and mouth. It has been recommended by several governing medical bodies that each area of
      medicine, should develop its own guidelines for sedation. Therefore, there is a need to
      research the application of capnography for dental sedation. The proposed study will take
      place at a university hospital site. Patients will be randomly divided into two groups. Both
      groups will receive sedation in the normal way. The study group will have capnography
      monitoring added. The study will look for differences in breathing between the two groups.
      Additional information regarding other aspects of monitoring will also be obtained. The
      results from the proposed study may help to improve patient safety and change current
      practice during sedation for dentistry.
    

Detailed description: 
      Background Intravenous sedation allows procedures to be performed in dentistry, and other
      areas of medicine beyond the operating room. Its application in each area is tailored to the
      requirements of the relevant procedure, the setting and the levels of operator training and
      expertise. The Academy of Medical Royal Colleges emphasises that each speciality must produce
      its own form of guidance in the use of sedative techniques. The following definition for
      conscious sedation in dentistry is accepted by the General Dental Council and the Dental
      Sedation Teachers Group: "A technique in which the use of a drug or drugs produces a state of
      depression of the central nervous system enabling treatment to be carried out, but during
      which verbal contact with the patient is maintained throughout the period of sedation. The
      drugs and techniques used to provide conscious sedation for dental treatment should carry a
      margin of safety wide enough to render loss of consciousness unlikely". The Standing Dental
      Advisory Committee Guidance 2003, which remains the standard of guidance in the UK, further
      states: "Any technique resulting in the loss of consciousness is defined as general
      anaesthesia and in the UKm 'deep sedation' is considered within this category". To summarise;
      dental sedation lies within the range of minimal to moderate sedation on the sedation
      continuum i.e. conscious sedation. Deep sedation is to be avoided in this setting.

      Dentists who have completed a recognised postgraduate course can practice conscious sedation
      independently. For intravenous sedation, dentists use a "standard" conscious sedation
      technique, defined as "intravenous sedation", using midazolam alone. The drug is titrated to
      an end-point; it is rapid in onset and possesses a short duration of action, which means that
      midazolam is very useful in the field of dental sedation.

      The current standard of monitoring for patients is clinical monitoring, which must be
      supplemented by pulse oximetry and blood pressure readings. The most important side effect of
      midazolam is respiratory depression.

      Although it is generally considered a safe practice, conscious sedation is not entirely
      risk-free.Ventilation (breathing) and oxygenation are related but seperate physiological
      processes. During the process of sedation, clinicians rely on pulse oximetry as a surrogate
      measure of ventilation. Capnography, a staple gold standard in general anaesthesia, is
      becoming an increasingly important area of interest for procedural sedation, with studies
      from other settings suggesting, capnography to be an effective ventilatory monitor for
      sedated patients.

      One significant limitation of pulse oximetry is the lag time; this means that the partial
      pressure of oxygen may decrease significantly before the pulse oximeter signals the fall.

      Reviewing the literature Previous studies on capnography for sedation are difficult to
      summarise. A review of the available literature has shown a relative paucity of randomised
      trials and no trials in the dental setting. Three trials from other settings are summarised
      here. Beitz et al (2012): A total of 760 patients were enrolled. Patients received 2L/min of
      supplemental oxygen. The intention-to-treat analysis revealed a significant reduction in the
      incidence of oxygen desaturation in the capnography arm in comparison with the conventional
      arm (38.9% vs. 53.2%). The study conclusion was that additional capnography monitoring
      reduces the incidence of oxygen desaturation and hypoxemia during propofol sedation for
      colonoscopy. Deitch et al (2010): A total of 132 patients in an emergency room setting.
      Hypoxia was defined as an SpO2 < 93%. The incidence of oxygen desaturation in the capnography
      arm in comparison with the conventional arm was 25% vs. 42%. All patients received
      supplemental oxygen (3L/minute). Conclusion: The addition of capnography to standard
      monitoring reduced the incidence of hypoxia and provided advanced warning for all hypoxic
      events. Qadeer et al (2009):This trial showed a significantly reduced rate of hypoxia (46% vs
      69%), defined as an oximetry reading < 90% for 15 sec. There was a relatively large cohort of
      ASA 3 patients in the study. 147 patients received supplemental oxygen. The study conclusion
      was that capnography monitoring of respiratory activity improves patient safety during
      procedural sedation for elective endoscopy.

      Waugh et al (2010) conducted a meta - analysis, the main finding being that during procedural
      sedation , cases of respiratory depression were 17.6 times more likely to be detected if
      monitored by capnography than cases not monitored by capnography ( 95% CI, 2.5-122.1).

      The results from the three randomised trials and the meta-analysis cannot be generalised and
      extrapolated to the standard dental sedation technique because of:

        1. Different patient populations The reviewed studies contain many elderly patients who are
           known to be more sensitive to sedative drugs and more likely to have co - morbidities.
           For standard dental sedation the age is less than 65 years.

        2. Supplemental Oxygen In standard dental technique patients breath room air. In the
           reviewed studies supplemental oxygen was often administered.

        3. Drugs Different drugs were used to achieve sedation in the reviewed studies e.g.
           Propofol and Ketamine.

        4. Analgesia Local anaesthetic is employed for analgesia in dentistry. In the reviewed
           studies, analgesia was often achieved with the use of intravenous agents such as
           opioids. The synergistic effect of drugs used in combination are likely to have resulted
           in increased respiratory depression.

        5. Desaturation (SpO2) For the standard dental sedation technique an SpO2< 95% is regarded
           as the threshold for early desaturation.This is a reasonable threshold in this setting
           where sedation is administered by a non-anaesthetist outside of the operating room. In
           the reviewed studies the thresholds varied. Deitch et al used a threshold < 93% and
           Qadeer et al. <90%.

        6. Depth of sedation Varied between the studies and in some cases was beyond conscious
           sedation.

      Aim:

      The aim of this randomized, controlled study is to determine whether early intervention based
      upon data from capnographic monitoring reduces the incidence of arterial oxygen desaturation
      during midazolam sedation for dentistry.

      Objectives:

        1. Determine if early intervention based on capnography will influence the incidence of
           arterial oxygen desaturation.

        2. Characterise the ETCO2, respiratory rate and SPO2 at baseline pre sedation, during
           sedation and post sedation.

      This will be a prospective, randomised controlled trial on dental patients receiving
      intravenous conscious sedation with midazolam.

      Goal: To determine whether use by the dental team of real - time capnography is associated
      with a decrease in the incidence of oxygen desaturation (hypoxia) compared with standard
      monitoring alone during intravenous sedation with midazolam for dentistry.

      Setting and selection of participants:

      Patients attending the oral surgery department and the dental theatre for sedation procedures
      at Cork University dentalo school and Hospital and Cork University Hospital will be
      prospectively invited to take part. Patients will be randomly assigned to the study group
      (standard monitoring and capnography) or control group (standard monitoring and blinded
      capnography) . The sedation team will be blinded to the randomisation choice until after
      enrolment. A member of staff not directly involved in the study will conduct the
      randomisation. There is evidence for utilising intravenous midazolam in the age group 14 to
      16years (post pubertal) for dentistry. Including this age cohort ( with parental consent)
      will provide additional research data to add to the body of evidence. Patients will have
      intravenous sedation with midazolam primarily for the relief of anxiety and to help them to
      accept invasive procedures. The operative procedures will range from simple extractions to
      minor oral surgery procedures such as the removal of impacted wisdom teeth.

      Pre sedation visit:

      Patients will be assessed as to their suitability for sedation at a separate pre sedation
      visit Baseline capnography and pulse oximetry data will be collected at this visit. Patients
      meeting the inclusion criteria will be given written information about the study. This
      information will be written in lay language.

      Enrolment to the study will take place at the beginning of the subsequent treatment visit for
      those patients who consent to take part having had time to consider the information provided
      about the study at the pre assessment visit. Patients will receive pre sedation instructions.
      Standard electronic monitoring (pulse oximetry, pulse rate and blood pressure) will be
      available to the clinical staff at all times. Standard dental sedation will be used according
      to the institutions policy and protocol. A capnostream 20 monitor ( Oridian medical, Needham,
      MA), using a disposable oral - nasal CO2 cannula capable of delivering oxygen, with an oral
      sampling port to accommodate mouth breathing will be attached to all patients. The
      capnostream 20 monitor displays oximetry and CO2 waveform and calculates ETCO2. The
      capnography monitor will be calibrated every day of the study.

      Continuous recording of SpO2, Heart rate, ETCO2 and respiratory rate will be stored on a
      laptop computer via specialised software for post hoc analysis. In addition, clinical staff
      will keep paper records of the patients' age, sex, body mass index, ASA status and medical
      history. All patients will be assigned a code to maintain confidentiality.

      Before the study, all clinicians and nursing staff will be trained in the interpretation of
      capnography in relation to respiratory depression including waveform interpretation. A
      laminated interpretation card will be attached to the monitor as a reminder. The sedation
      team will perform conscious sedation according to standard protocol for dental sedation.
      Intervention for an adverse event will be based on judgement and clinician expertise with or
      without capnography depending on randomisation arm. In the capnography arm,in addition to
      standard monitoring, changes in the shape of the capnography waveform, ETCO2 numeric changes
      will be considered as triggers to take measures to avoid desaturation. In the control group,
      capnography will be blinded by placing an opaque screen over the capnostream 20
      capnographydisplay of ETCO2 values, respiratory rate and waveform. Pulse oximetry will
      continue to be displayed. Baseline monitoring data will be obtained for at least 2 minutes
      prior to the first infusion. Midazolam will be titrated at a rate of one mg per minute to an
      end point. Most patients are discharged 60 minutes after the last increment provided they are
      fit for discharge. We propose collecting study data until discharge.

      All patients will receive written pre and post sedation instructions. the benzodiazepine
      antagonist , flumazenil will be available in the sedation suite at all times in addition to
      emergency drugs and equipment.

      The Null hypothesis states: The study group is the same or equal to the control group in
      terms of hypoxemia rates i.e arterial oxygen desaturation.
    

Intervention name(s): Capnography
Intervention type(s): Other
Intervention description(s): Capnography waveform and capnometry readings
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Prevention
Keywords: Midazolam; Endtidal carbon dioxide; Desaturation