In a blog post written in December 2012, the question was asked as to whether paediatric i-gel® was an advance over other supraglottic airways? The article reviewed the evidence already published and concluded that:
‘Clinical evidence takes time to build, and some of the studies looked at one size only and all studies have limitations. However, the above evidence suggests i-gel may yet prove to be “a genuine improvement on the pLMA”, as thought possible by White, Cook and Stoddart back in 2009.’
This was a reference to a comment in the excellent review article ‘A critique of elective pediatric supraglottic airway devices’ pubished in Pediatric Anesthesia by White et al, which aimed to present the evidence surrounding the use of currently available supraglottic airways (SADs) in routine paediatric anaesthetic practice. It was also one of the first papers to divide SADs in to first and second generation devices, although the first paper to describe the classification fully was ‘Recent developments in efficacy and safety of supraglottic airway devices’ by Cook and Howes. In the White et al review, first generation devices were described as simple airway tubes, and second generation devices, such as i-gel®, as incorporating ‘specific design features to improve safety by protecting against regurgitation and aspiration’.
The White et al review concluded that ‘The pLMA has yet to be outperformed by any other SAD, making it the premier SAD in children and the benchmark by which newer second generation devices should now be compared’.
Five years on and almost 2 years since my earlier blog post, what additional evidence has been published for the paediatric sizes of Intersurgical i-gel® and does this new data help us to draw a more definitive conclusion to the question I asked back in 2012?
The new data includes two meta-analyses and a number of comparative studies. There are also some interesting letters, review articles and one survey of current UK practice for paediatric SADs. The data ranges from an assessment of the effect of the device on intraocular pressure in paediatric patients who received sevoflurane or desflurane during strabismus surgery to fibreoptic assessment of laryngeal positioning to a clinical evaluation of airway management with the device during MRI examination.
The two meta-analyses were both published in 2014. The first, ‘A systematic review and meta-analysis of the i-gel vs laryngeal mask airway in children’ by Choi et al included nine Randomised Controlled Trials (RCTs) comparing i-gel to different types of laryngeal mask in children. The different types of laryngeal masks were the LMA ProSeal® (pLMA), the LMA Classic® (cLMA), the LMA Supreme® (sLMA) and the Ambu® AuraOnce™ (ALMA).
All four of these devices are quite different in design, and although there is a subgroup analysis for the different types of device, the overall conclusions are a comment on i-gel® in comparison to all the laryngeal masks as a collective group. The conclusions were that, ‘i-gel was similar to LMAs when used in children and delivered ventilation pressures 3cm H20 higher than LMAs. Few complications were reported with either airway.’
The other meta-analysis, ‘Evaluation of i-gel airway in children: a meta analysis’, by Maitra et al and published in Pediatric Anesthesia, included nine RCTs where i-gel® had been compared to the cLMA and/or the pLMA . The authors concluded that ‘The i-gel® airway is at least equally effective with laryngeal mask airway ProSeal and laryngeal mask airway Classic and provides a significantly higher oropharyngeal leak pressure than both the laryngeal masks.’ The authors of both meta-analyses acknowledge a number of limitations to their papers. An important consideration is certainly whether any statistically significant differences identified between devices are also clinically significant.
A particularly interesting article, published in 2013, is ‘Current practice of pediatric supraglottic airway devices – a survey of members of the Association of Paediatric Anaesthetists of Great Britain and Ireland (APAGBI)’. It assessed usage of SADs in routine and difficult airways in the UK by distributing a survey with sixteen questions to all UK members of the APAGBI. Two hundred and fourty-four members replied.
88% ‘favoured’ first generation SADs for routine use and 85% ‘preferentially’ for use in the failed intubation scenario. As the pLMA, a second generation device, is often considered the premier SAD for use in children, this is perhaps a little surprising. In fact, only 1% of responders confirmed the pLMA as their first choice/usual SAD. 49% would never use a SAD on a patient weighing less than 5kg. Only 15% ‘felt that an esophageal drainage tube was an important feature.’
The authors confirm that, ‘Fibreoptic guided intubation via an SAD is used electively by 46% of respondents, and only 3% regularly employ this technique. 17% have used the technique in an emergency, 20% have only practiced it on a manikin, and 9% have never used or seen this technique in any situation.’
With regard to i-gel, 37% of respondents reported they had access to the device. This compared to 25% with access to the pLMA and 14% to the sLMA. However, only 1% confirmed i-gel® as their first choice/usual SAD. The same percentage as reported for the pLMA. 87% had access to a classically shaped laryngeal mask airway, with 77% using it as their first-choice/usual SAD. Only 15% considered an esophageal drain channel as an important design feature.
So why the low use and apparent limited interest in second generation SADs, such as i-gel® and the pLMA amongst members of the APAGBI? The authors suggest there may be a number of reasons for the slower adoption than with the adult sizes, such as paediatric sizes coming onto the market later than adult sizes, the bulkier design of paediatric sizes and because aspiration associated with SAD use is seen less frequently and has less morbidity in children when compared with adults. It maybe the potential safety features are therefore considered by paediatric anaesthetists to be less essential.
The authors conclude that, ‘Research currently has little influence over the choice of which SAD to use, which is more likely determined by personal choice and departmental preference.’
Whilst writing this review, two additional papers of interest were published in Anaesthesia. The first, ‘A performance comparison of the paediatric i-gel with other supraglottic airway devices’ by Smith & Bailey includes data from fourteen RCTs and eight observational studies. The authors conclude that, ‘the i-gel is at least equivalent to other supraglottic airway devices curently available for use in children, and may enable a higher oropharyngeal leak pressure and an improved fibreoptic view of the glottis.’
The other paper is a particularly interesting editorial, entitled, ‘Which supraglottic airway will serve my patient best?, also published in Anaesthesia. Whilst not specifically focussed on paediatric SADs, the paper mentions two of the meta-analyses discussed in this blog post.
The authors Kristensen, Teoh and Asai consider how the ‘right’ device should be chosen, when a new device can be introduced into clinical practice, the role of manikin studies and manufacturer’s responsibilities. They also discuss the ADEPT guidance formulated by the Difficult Airway Society (DAS).
The authors comment that, ‘Until significantly better features of a new airway device relating to clinically important outcome measures have been shown, we should be cautious about replacing the conventional device with a new one…We can judge whether or not a new device has a clinically meaningful difference (superiority) to the conventional device, mainly by assessing the results of randomised controlled studies and meta-analyses. Nevertheless, if randomised controlled studies only show statistically significant differences that are not clinically meaningful, the reports of meta-analyses will not provide clinically meaningful information for our decision making.’
So what conclusions can we draw from the new data published for i-gel? Is the device superior to other paediatric supraglottic airways already available? Well, the new data is varied in subject matter, includes a number of RCTs, comparative studies and meta-analyses. Most of the data is encouraging and some possible advantages have been identified. However, there are always areas where more data is required or desirable. I will leave you to review the evidence for yourself and draw your own conclusions.
i-gel is a registered trademark of Intersurgical Ltd. LMA Classic, LMA ProSeal, LMA Unique and LMA Supreme are registered trade marks of the Laryngeal Mask Company Ltd. cLMA, pLMA, and sLMA are abbreviations used in some journal articles. They refer to the LMA Classic, LMA Proseal and LMA Supreme respectively. Ambu is a registered trademark of Ambu A/S.