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Re: Caution regarding the early use of mask ventilation in Congenital Central Hypoventilation Syndrome

We welcome the publication in ADC of the recent article by Pavanasam et al (Archives of Disease in Childhood 2008) (1), which highlights some of the challenges in providing ventilation support for children and infants with congenital central hypoventilation syndrome (CCHS). However we are anxious that readers may mistake the enthusiasm of this group for mask ventilation as evidence that it is superior to other modalities, particularly when initiating ventilation support during infancy.

Although the authors report a retrospective study of 15 patients, we note that only six of these children were initiated on mask ventilation and, given the young age of this group, no follow up data have been presented whether in favour of or against non-invasive ventilation in this situation. The data presented relates to children who have switched from another modality (as we understand the data 6/9) from negative pressure ventilation – another local curio that is little practised for this condition in other UK institutions. Therefore, the evidence presented that families prefer mask ventilation is not generalisable to other UK centres.

We are concerned that the paper as it stands gives a biased view in favour of mask ventilation without adequately addressing its pros and cons compared with the other conventional approach used by us and by other UK and overseas centres caring for sizeable numbers of infants with CCHS; namely that of tracheostomy ventilation (2). We would hasten to point out that we make no claims in favour of the latter, but would simply wish to indicate the paucity of evidence that exists in this field that detracts from some of the more extreme ex cathedra statements made by the authors. The disadvantages of mask ventilation are rather underplayed and include major problems of mask fitting with the limited availability of masks for young children and the not inconsiderable risk of mid facial hypoplasia. We do not disagree with the authors that the latter is rarely encountered in older children converted to mask ventilation but, given the specific risk of mid-facial abnormalities in children with CCHS, this may be exacerbated by mask application during a rapid period of facial growth in early childhood. Whilst not wishing to make light of the considerable morbidity and mortality associated with tracheostomy in children, we question whether it is fair to cite data from single centre series in which tracheostomy was performed for a whole range of reasons including airway abnormalities, rather than as an adjunct to support ventilation. We find it difficult to understand how mask ventilation is ‘more efficient’ than invasive ventilation through a tracheostomy or endotracheal tube. In our experience this is rarely the case, but in the absence of any objective evidence presented in support of this statement, we find it difficult to comment further.

Children with CCHS commonly require ventilation when awake at times of minor illness in early childhood, leading to problems with compliance and feeding for children receiving mask ventilation.

We find the authors’ arguments for the health economic benefits of mask ventilation staggeringly naïve. Again they are guilty of unfair comparisons, citing the annual cost of ventilating a tracheostomised child with round the clock carers in comparison with the equipment-only costs of a child on non-invasive ventilation. The critical point here is not the mode of ventilation but the degree and severity of the control of breathing disorder and the needs of the individual child and family. The physiological impact on the child does not differ and, although tracheostomy ventilation may entail frequent airway toilet and attention to clearance of secretions, this is offset for mask ventilated children by the need for regular attention to mask fitting and a potentially less secure interface between child and ventilator. The reader must be aware that without sustained ventilation support, however it is provided, the child’s life is at risk, and the modality of ventilation does not change the need for close observation and availability of a skilled carer.

Finally the proposed benefits in time to discharge are not borne out by any data presented in this paper. Over the past 5 years, we have reduced our time to discharge home from 1-2 years down to 4 months from diagnosis in children with CCHS on tracheostomy ventilation. Those with longer hospital stays are those with complex comorbidities or particular home circumstances that necessitate specific interventions to render discharge a safe and successful outcome. We would contend that this is largely independent of ventilation mode.

The authors are to be congratulated for their work in this difficult and evolving field and we greatly look forward to the reports of intermediate and long term outcomes from a group of infants that have started mask ventilation ab initio. In the meantime the choice of ventilation mode for this group of patients continues to be governed by opinion rather than evidence, as evidenced all too clearly by this publication.

Reference List

(1) Pavanasam R, Boit P, Samuels M. Mask ventilation in the early management of Congenital Central Hypoventilation Syndrome. Archives of Disease in Childhood-Fetal and Neonatal Edition. In press 2008.