Conscious sedation for children

Abstract

Having read the recent article ‘A randomised controlled trial of paediatric conscious sedation for dental treatment using intravenous midazolam combined with inhaled nitrous oxide or nitrous oxide/sevoflurane’ (Averley et al. Anaesthesia 2004; 59: 844–52) I have the following two points to raise. Firstly, the paper described the combined use of intravenous midazolam with sevoflurane/nitrous oxide mixture for children aged 6–14 years having chair dental treatment with a 93% (249/267 children) success rate. The results also showed that 34 of 151 children who failed the dental treatment were managed with alternative conscious sedation techniques by administration of additional sedative agents but the article did not describe which and how many agents were used. The risks from the combined use of intravenous sedative drugs with sevoflurane/nitrous oxide triggers memories of the tragic events relating to the death of five healthy children who received dental general anaesthesia (GA) in dental practices in England between 1996 and 1998. Much adverse publicity followed and there was public and professional concern over standards of practice. This was soon followed by a ban on the use of dental GA outside hospital settings from January 2002 [1]. In 2001, we searched for a new, safe and effective inhalation conscious sedation technique that might reduce the need for dental GA, particularly in difficult children where nitrous oxide sedation has failed and the use of intravenous sedative drugs is considered unsuitable or carries an unacceptable risk. We investigated the addition of low concentrations (0.1–0.3%) of sevoflurane to 40% nitrous oxide given through a nasal mask for chair dental treatment. The initial pilot study showed it was successful in 92% of cases [2]. Next, we conducted a randomised controlled clinical trial to compare this mixture with nitrous oxide alone for inhalation conscious sedation. The results showed that the technique was effective in 89% (215/241 children) in the sevoflurane/nitrous oxide group compared with 52% (89/170 children) in the nitrous oxide only group [3]. No adverse side-effects were recorded in either group. The study concluded that, for every 100 children treated with sevoflurane/nitrous oxide mixture, 37 children would be saved a general anaesthetic if given combined sevoflurane and nitrous oxide mixture rather than nitrous oxide alone. The use of sevoflurane/nitrous oxide mixture proved to be safe, practical and significantly more effective inhalation conscious sedation than nitrous oxide alone. Since these publications, the new technique has been successfully used on hundreds of children and adult patients both in and out of the hospital setting. The article confirmed that the use of inhaled sevoflurane/nitrous oxide mixture has been demonstrated to be successful as a paediatric conscious sedation technique with no adverse events. So, why are the authors opting to take an unnecessary risk by adding intravenous sedative drugs to the sevoflurane/nitrous oxide mixture? One can argue that this trial showed that a combination of inhalation sedation and intravenous midazolam rather than intravenous midazolam alone, improved the level of co-operation during dental treatment and produced good amnesia. However, several studies have concluded that the amnesia is not completely reliable, especially at lower doses of midazolam [4–6]. Other studies have shown no difference in the degree of amnesia between midazolam and sevoflurane [7] or nitrous oxide sedation [8]. Cote et al. investigated the adverse events of sedative drugs in paediatric patients and concluded that a poor outcome was more commonly associated with the use of more than one sedative drug even when the drugs were administered within acceptable dose limits [9]. Poorly controlled conscious sedation may result in deep sedation or even general anaesthesia with the inherent risks involved. I am certain that the majority of my fellow anaesthetists who are involved with paediatric dental anaesthesia and sedation will appreciate that this complex modified technique can only compromise children's safety. My second concern relates to the authors advocating the use of their new combined technique in primary dental care settings. The authors have announced publicly through the media that they are calling for reform of dental services to allow alternatives to hospital-based GA for dental procedures to be offered in specialist practices. My argument is simply that if a young child can't cope in the dental chair with the use of inhalation conscious sedation with nitrous oxide alone or sevoflurane/nitrous oxide mixture, perhaps the safest option is to refer this child to the hospital where he or she can receive the appropriate dental care under sedation or anaesthesia, provided in a safer environment where there are properly trained personnel, backed up by PALS certified paediatricians and on-site intensive care facilities. I urge the Royal College of Anaesthetists, the Association of Anaesthetists of Great Britain and Ireland and the General Dental Council to impose a new ban on the use of intravenous sedative drugs on children under the age of 16 years, having dental treatment outside a hospital setting. Dr Lahoud makes two related points. The first is that poorly controlled conscious sedation can result in deep sedation, with potentially greater risks to the patient, and the second is that, in view of this risk, sedation techniques using intravenous agents should be restricted to the hospital setting. We would agree with the first point; this is a recognised risk of any sedation procedure and this is why we go to some lengths in our paper to indicate that appropriate training of the sedation team, including the anaesthetist and dentist, is an essential prerequisite for practising these techniques. However, although this is a risk, it is one that is relatively easy to eliminate. Using these techniques the children are conscious, co-operative and responsive to verbal commands at all times. To put this in perspective: for the children in this study (unlike those reported in the papers described by Dr Lahoud in his references 2 and 3), these techniques were used only for the most anxious, unco-operative and dentally complex cases where the only alternative was general anaesthesia, with much greater attendant risks. Regarding the second point, that these techniques should only be practised in a secondary care setting, we find it difficult to comprehend the logic required to reach this conclusion. The safety issue has nothing to do with location, it has to do with trained and integrated teams who work together with a conscious child. If we take the argument about the location of services to its logical conclusion, then we would be better having inappropriately trained teams working in a hospital, so that they can recover the child there when the sedation is badly managed. The issue is expertise, facilities and service organisation, not location. This is also about taking a long-term view. Effective sedation in a primary care setting allows the dentist the opportunity to address all of the child's dental needs in a specialised and minimally threatening environment, rather than repeated cycles of failed dental interventions under general anaesthesia. Whatever Dr Lahoud's assertions, both the anxiolytic and amnesic properties of midazolam are important features. There is a strong evidence base to support its use in children and adults, and this an important aspect of the management of the child's fear. The only way to move forward and provide a safer and more appropriate service for patients is to establish an evidence base built on the foundations of properly conducted research, including randomised controlled trials, and our paper provides quantitative data to help us to do that. Whilst we welcome the debate, it is our belief that a ban on the use of intravenous drugs for sedation, even when used by experienced consultant anaesthetists, would be an unnecessary and retrograde step and would serve nobody well. Let us think about working together in innovative ways to take our services forwards, not backwards. P. AverleyQueensway Dental Practice & Anxiety Management Clinic Billingham TS23 2NT, UK E-mail: [email protected]