Dental anxiety is very common, affecting 22% of the population. One way to increase access to dental care is by the use of BDZs in conscious sedation. These drugs are known to be safe when titrated. BDZs work by stimulating GABAA receptors within inhibitory pathways of the CNS. A consequence of this is a reduction in respiratory drive. Thus assessing saturation of peripheral oxygen (SpO2) is mandatory. A pulse oximeter is normally used to do this. However a pulse oximeter cannot detect changes in CO2 which could result from a reduction in ventilatory drive. Many practitioners prescribe supplemental oxygen to compensate for hypoventilation, which can inhibit the ability of pulse oximetry to detect hypoventilation. Transcutaneous CO2 monitoring is currently used in ICUs and neonatal units. It may, however, have a place in conscious sedation dentistry. It can be used to detect changes in CO2, and is not affected by supplemental oxygen.