Sir, intravenous conscious sedation for paediatric dentistry is for various reasons a very controversial issue. One of the main issues of concern is the use of combinations of intravenous drugs, called polypharmacy.

I am currently busy with a pilot study to look at the various factors that may contribute to risk. So far we have entered into the study, using polypharmacy, 154 children, 3–10 years of age, undergoing dental procedures under local anaesthesia and sedation. Our target is conscious sedation. Our sedation technique includes the following drugs: midazolam, ketamine, propofol and remifentanil.

We are using the DOCS scale to evaluate safety and efficacy of the sedation technique. According to this scale, if the score is between −2 and +2 the sedation technique is considered to be in the safe zone.

Children are divided into the following age groups: under 5 years (70), 5–8 years (50), and over 8 years (34).

With this technique done by an experienced sedationist, under ideal circumstances, in a sedation unit, next to the operating theatres, 153 children were rated as between +2 and −2 on the DOCS scale, indicating a safe zone. One child had a −3 rating because of respiratory obstruction caused by depression of the chin by the dentist.

A rating of −2, indicating increased risk, was documented in the following groups: children under 5 years: 14.2%; children 5–8 years: 8%; and children over 8 years: 0%.

A decrease in oxygen saturation of <92% was noted in 14/152 = 9% of children. In children under 5 years 12/70 = 17%, had a drop in oxygen saturation. It is quite interesting to note that the drop in oxygen saturation was caused by flexion of the head in six of the children, depression of the chin in two children, and excessive water in the mouth in four children – all preventable causes. No incidences of laryngospasm or bronchospasm were seen. In children over eight years old no adverse events were seen. This may indicate that children of this age group may have a lower risk for adverse events during intravenous paediatric sedation for dentistry.

It is well known that upper airway narrowing is most likely to appear in pharyngeal structures in children <8 years – they are probably the group at risk during sedation. Children are especially vulnerable because of a smaller diameter of their airways and a high incidence of adeno-tonsillar hypertrophy. It is our belief that in paediatric sedation – done by an experienced, trained sedationist – it is not always the drugs (polypharmacy) that cause adverse events. Other factors also increase risk and lead to adverse events: the 'human factor'.

Risk will be increased if a pre-operative assessment is not done, monitoring is neglected, multiple drugs are used to keep a patient still (if you target immobility you target deep sedation) and the patient is prematurely discharged.

Risk is also related to the experience of the sedationist (training), secretions, and the position of the head during sedation – the airway – it is all about the airway!

The dentist as operator may also contribute to risk by depression of the mandible, and not controlling the suction of water during drilling.

The above-mentioned pilot study shows that 'other factors' may play a role in increasing risk during paediatric sedation. We must be careful in just blaming drugs as the only cause of adverse events.