In 2009, Pediatric Anesthesia published a paper by White, Cook and Stoddart, entitled, ‘A critique of elective pediatric supraglottic airway devices’, which aimed to present the evidence surrounding the use of currently available supraglottic airways (SADs) in routine anaesthetic practice. It was one of the first papers to divide SADs in to first and second generation devices. 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 review highlighted that, apart from the LMA Classic® (cLMA) and LMA Proseal® (pLMA), there was a lack of high quality data of efficacy for SADs, stating that, ‘The best evidence requires a randomized controlled trial comparing a new device against an established alternative, properly powered to detect clinically relevant differences in clinically important outcomes. Such studies in children are rare. Safety data is even harder to establish, particularly for rare events such as aspiration’.
Whilst the authors did comment on the i-gel, at the time of their review paediatric sizes of the device were not available. However, they did note the i-gel offers, ‘the possibility of a genuine improvement on the pLMA’, based on the stability provided in adult sizes by the elliptoid shape of the device, but that it remained to be seen whether this stability would be retained in the paediatric sizes. The 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’.
Paediatric sizes of i-gel (fig 1) became available in the latter half of 2009, extending the lower weight range from 30kg to 2kg. As with the adult sizes, the paediatric sizes have a non-inflatable cuff, a gastric channel (except size 1), an integral bite block and a buccal cavity stabiliser. Details of the applicable weight range for each size are shown below (fig 2).
The first independent data on the use of the new paediatric sizes came from the Hautepierre University Hospital of Strasbourg, who presented an abstract on the device at the SFAR Congress in Paris in September 2009 and at the Amercian Society of Anesthesiologists (ASA) Annual Meeting in October 2009, entitled, ‘The i-gel in paediatric surgery: Initial series’. This abstract reported on 50 insertions of the device in patients between 6 months and 14 years. Stability of the device and avoidance of intubation were seen as advantages. An interview with Professor Pierre Diemunsch, Consultant at the Hautepierre University Hospital, discussing their findings is available on YouTube.
A number of observational/cohort studies followed. Beringer et al studied the i-gel in 120 anaesthetised patients to assess efficacy and usability. First time insertion success was 92%, overall insertion success was 99% and the median leak (seal) pressure was 20cm H2O. One child regurgitated without aspirating. 16 manipulations were required in 11 children to improve the airway. The authors concluded that, ‘other complications and side effects were infrequent. The i-gel was inserted without complications, establishing a clear airway and enabling spontaneous and controlled ventilation in 113 (94%) children.’
Hughes et al studied the device in 154 children. First time insertion success was 93.5%, overall insertion success was 99.3%. The median leak (seal) pressure was 20cm H2O. The authors concluded that i-gel provided a satisfactory airway during anesthesia for spontaneously breathing infants and children, but felt that to ensure a clear airway, considerable vigilance is required when fixing the device in the mouth.
Fixation is important. The instructions for use for the paediatric i-gel make it clear that as soon as insertion has been successfully completed, the i-gel should be held in place until and whilst the device is secured in place with tape maxilla to maxilla.
Randomised comparative studies followed. The first by Theiler et al, compared i-gel to the Ambu® AuraOnce. This was followed by comparisons to the cLMA . Lee et al found a similar leak pressure between i-gel and the cLMA, but a shorter insertion time for i-gel – 17 secs median (IQR 13.8 – 20.0) v 21.0 secs median (IQR 17.5 – 25.0) and an improved glottic view.
A summary of seal pressures from published clinical studies for the paediatric sizes of i-gel is shown below (fig 3)
Considering the conclusion made by White, Cook and Stoddart, perhaps the most interesting comparisons are those to the pLMA.
Two such comparative studies have so far been published. The first was a randomised prospective study entitled, ‘Comparison of size 2 i-gel supraglottic airway with LMA-ProSeal and LMA-Classic in spontaneously breathing children undergoing elective surgery’, which compared the devices in 120 children aged 2-5 years scheduled for surgery of <1 hour duration. The oropharyngeal seal pressure for i-gel was higher than both the cLMA and the pLMA: 26, 22 and 23 cmH20 respectively. First time insertion success was also higher for the i-gel than both the cLMA and the pLMA, 95%, 90% and 90% respectively. The authors concluded that ‘Pediatric size 2 i-gel is easy to insert and provides higher OSP compared with the same size pLMA and cLMA in spontaneously breathing children undergoing elective surgery. It may be a safe alternative to LMA in day care surgeries.
In November 2012, Acta Anaesthesiologica Scandinavica, published a crossover design study by Gasteiger, Brimacombe, Oswald, Perkhofer, Tonin, Keller and Tiefenthaler, entitled ‘LMA ProSeal® vs i-gel in ventilated children: a randomised, crossover study using the size 2 mask‘. The paper studied fifty one children aged 1.5 – 6 years. Leak pressure for both devices was similar, as was fibreoptic position, with the vocal cords visible from the distal airway tube in 94% and 96% respectively. The authors concluded that ‘oropharyngeal leak pressure and fibreoptic position of the airway tube are similar for the size 2 LMA ProSeal® and i-gel in non-paralysed ventilated children’
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.
Interestingly, a number of other studies on paediatric i-gel have recently been published, including, ‘A randomised equivalence trial comparing the i-gel and the laryngeal mask airway Supreme in children‘, in which i-gel had a higher seal pressure than the sLMA, 20 (IQR 18-25) v 17 (14-22) cm H20 respectively.
‘A comparison of three supraglottic airway devices used by healthcare professionals during paediatric resuscitation simulation‘ compared the i-gel to the Laryngeal Tube (LTS) and the LMA Unique® (uLMA) in manikins. A total of 66 healthcare providers, 22 paramedics, 22 nurse anaesthetists and 22 anaesthesia residents participated in the study. The authors concluded that ‘In terms of both the time required for successful placement and the rate of successful placement, the i-gel is superior to the laryngeal mask and tube in paediatric resuscitation simulations by healthcare workers with different levels of experience with paediatric airway management‘.
More data is awaited.
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, uLMA and sLMA are abbreviations used in some journal articles. They refer to the LMA Classic, LMA Proseal, LMA Unique and LMA Supreme respectively. Ambu is a registered trademark of Ambu A/S.