Moderate Sedation in Paediatric Dental Patients
The article Outcomes of moderate sedation in paediatric dental patients investigates various combinations of midazolam dosage and modalities of delivery in combination with N2O/O2 at a 50/50 ratio. Dentists experienced in N2O/O2 on paediatric patients would recognize that patients vary markedly in their reaction to different ratios of N2O/O2. Initially it may have been better to have titrated the dose (ratio) of N2O/O2 to effect. Others, including me, have found that paediatric patients can vary between 20% to 60% of nitrous oxide required. Too little and the technique is sure to fail; too much and the patient is over sedated, leading to increased anxiety and failure. This may have lead to the increase in ‘failures’, especially in Group 4.
Secondly, the term ‘moderate sedation’ is not used by the Australian and New Zealand College of Anaesthetists (ANZCA), the Australian Society of Dental Anaesthesiology (ASDA), nor the Dental Board of Australia (DBA). The described technique is expressly forbidden by the DBA by those other than dentists with the Graduate Diploma in Clinical Dentistry (Conscious Sedation and Pain Control) or its equivalent. The use of polypharmacology and anything other than minimal sedation requires the sedating dentist to have the relevant postgraduate qualifications as mentioned above.
The use of BIS monitoring of the sedated paediatric patient is questionable given that Musizza and Ribaric found that ‘EEG (e.g. BIS) or AEP based anaesthesia monitoring devices are not able to reliably assess the patient's depth of anaesthesia when ketamine, xenon or nitrous oxide are used’, and ‘the effects of nitrous oxide on the raw EEG or on the BIS value are varied and therefore unpredictable’. Furthermore, Ibrahim et al. found ‘Individual BIS scores demonstrate significant variability, making it difficult to predict sedation depth. BIS was a better predictor of propofol sedation than sevoflurane or midazolam’.
In the conclusion, the article states ‘… both intranasal and oral sedation using midazolam in conjunction with nitrous oxide found to be effective methods’ and ‘… can be used safely and effectively …’. This conclusion is at odds with the findings as the article states that: three patients in Group 2 (oral sedation and nitrous) had BIS values between 72–75, given the variation in values; two oral sedation patients and one intranasal patient recorded low O2 saturations. This is particularly worrying given that 4–6 year olds have little in the way of respiratory reserves; four patients vomited on oral sedation, which is especially dangerous for the sedated patient given that there is a real possibility of aspiration; one had a nose bleed with intranasal sedation which may result in compromising the airway or even laryngospasm; and patients were treated in the hospital environment and not in a stand-alone dental surgery in the suburbs.
Given these results indicating significant morbidity, any reasonable practitioner versed in the art and science of sedation would conclude that this is indeed a dangerous technique for anyone not specifically trained. This is reflected by the fact that this technique has been associated with a number of paediatric deaths and morbidity worldwide. In 2000, Dr Kiera Mason of the Harvard Medical School reported 29 deaths associated with oral sedation in dentistry, a number which has grown significantly in the intervening 12 years. A google search on paediatric deaths with dental sedation highlights the increasing numbers in the USA alone. While some are not associated with midazolam and nitrous oxide sedation, most involve polypharmacology with drugs from the same family or similar actions.
This article cannot rightly conclude or infer that paediatric dentists (without the Diploma) can safely and effectively administer this form of sedation to their patients.