A Randomised Control Trial to Determine Whether Intervention Based on a Microstream Capnography-based Ventilation Monitoring System Will Decrease Hypoxaemaia During Intravenous Sedation With Midazolam.

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.