however , at times , conventional laryngoscopy and intubation may not be possible and alternative techniques of airway management such as supraglottic airway devices ( sads ) may be required .
both classic laryngeal mask airway ( clma ) and proseal laryngeal mask airway ( plma ) have been successfully used for securing a patent airway ; however , due to high - cuff pressure - related complications , they can cause mucosal damage , sore throat , hoarseness and nerve palsies .
the i - gel has thermoplastic elastomer gel with non - inflatable cuff and a channel for gastric suction catheter placement that precisely mirrors perilaryngeal anatomy , thereby no cuff inflation is required .
studies are now focusing on sads , which can provide ventilation with low peak airway pressure , higher compliance , low resistance and high leak pressure so that they can provide wider margin of safety for ventilation .
the primary aim of the present study was to compare oropharyngeal leak pressure of size 2 i - gel and plma for airway management in paediatric patients .
the secondary outcomes measured were number of insertion attempts , insertion time , ease of insertion of size sgds ( 2 i - gel or plma ) and orogastric catheter , quality of initial airway , fibre - optic grading and pulmonary mechanics .
this prospective , randomised controlled study was conducted during april 2013april 2014 after approval of the institutional ethics committee ( gmc / ta  i [ 19d]/2013/05428/22 ) and registration in the clinical trial registry india ( ctri/2013/08/003898 ) . after parental written informed consent , 100 children of american society of anesthesiologists physical status i and ii of either sex , aged between 2 and 6 years , weighing between 10 and 30 kg , scheduled for elective surgeries of < 1 h requiring general anaesthesia ( ga ) with controlled ventilation were enrolled .
the exclusion criteria were patients with upper respiratory tract infection , anticipated difficult airway , non - fasting status and cardiorespiratory disease .
all patients were kept fasting for 46 h and premedicated with 0.3 mg / kg midazolam syrup 30 min before surgery .
ga was induced with sevoflurane ( inspired concentration 46% ) with 50% nitrous oxide in oxygen , and then an intravenous ( i.v . )
access was established which was followed by fentanyl 2 g / kg , i.v . after checking for mask ventilation , neuromuscular blockade
atracurium besylate 0.5 mg / kg . the patient 's lungs were ventilated with a facemask for 3 min to allow for full relaxation of the jaw before placing the device .
patients were allocated just before device insertion to either size 2 plma or i - gel ( 50 patients each ) based on sequentially computer - generated numbers concealed in opaque sealed envelopes .
the anaesthesiologist inserting the device could not be blinded , but the assessor anaesthesiologist and patient were blinded to the group allocation .
the anaesthesiologist who inserted either of the two airway devices had performed at least 50 plma and 20 i - gel insertions .
size 2 i - gel was inserted by firmly holding the device such that the cuff outlet was facing the chin of the patient , and it was then guided along the hard palate until definitive resistance was felt .
the insertion of plma was performed as per the manufacturer 's recommendation , using the introducer technique .
a lubricated orogastric tube ( ogt ) was inserted through the drain tube after insertion of sgds .
correct ogt placement was determined by suction of fluid or detection of injected air by listening with a stethoscope over the epigastrium .
the plma or i - gel was then connected to the circle system of anaesthesia machine ( aestiva 5 7900 , ge healthcare , datex - ohmeda division , helsinki , finland ) using paediatric circle system .
effective ventilation of the device was judged as a square wave capnograph trace and bilateral chest movements on gentle manual ventilation . in the event of partial or complete airway obstruction or a significant air leak ,
a maximum of three insertion attempts were allowed before the device was considered a failure .
the time interval between picking up the i - gel or plma and obtaining an effective airway was recorded as insertion time .
the ease of insertion was graded as very easy  if the device could be inserted without any manipulation , easy  if there was only one manipulation required and difficult  if any difficulty more than that .
the quality of the initial airway was assessed during manual ventilation , with the pop - off valve set to limit peak airway pressure ( pip ) to 20 cm h2 o. the initial airway was judged as follows : excellent  no audible leak ; good  an audible leak with relevant loss of air but sufficient ventilation , as indicated by an etco2 < 40 mm hg and poor  clinically relevant loss of air and insufficient ventilation , requiring repositioning or replacement of the device .
air entry in the stomach and abnormal airway sounds over the larynx on auscultation were noted . after obtaining an effective airway , the oropharyngeal leak pressure
was determined by closing the expiratory valve of the circle system at a fixed gas flow of 3 l / min and the airway pressure ( maximum allowed 40 cm h2 o ) at which equilibrium reached was observed .
detection of an audible gas leakage at mouth and auscultation of gas leakage in the anterior neck was also performed in both the groups .
the patient 's lungs were ventilated with a tidal volume of 57 ml / kg , and the respiratory rate was adjusted to maintain etco2 of 3540 mm hg with inspiratory : expiratory ratio of 1:2 . after successful insertion of the device , fibre - optic assessment of airway tube ( pentax medical singapore pvt . ltd .
, 438a alexandra road , singapore ) was obtained by passing fibrescope through the airway tube .
the view was graded as 1 = vocal cords not seen ; 2 = vocal cords and anterior epiglottis visible ; 3 = vocal cords and posterior epiglottis visible ; 4 = only vocal cords visible .
pulmonary mechanics including compliance , resistance , mean airway pressure , peak airway pressures as shown on anaesthesia workstation were recorded in both the groups at 2 min and 5 min after device insertion .
we recorded any device failure , intraoperative displacement , gastric insufflation , regurgitation , laryngospasm , bronchospasm and airway obstruction .
data about fibre - optic position of the airway tube , ease of insertion of sgd , ease of ogt insertion , quality of initial airway , failed passage into the pharynx , malposition and the cause of failure were evaluated by the anaesthesiologist performing airway device insertion .
the assessor anaesthesiologist collected data regarding oropharyngeal leak pressure , insertion time , ventilation and pulmonary mechanics .
secondary outcomes included number of attempts , ease of device and ogt insertion , fibre - optic view and pulmonary mechanics . after the completion of surgery , anaesthesia was discontinued and residual neuromuscular blockade was antagonised with neostigmine methyl sulphate 0.05 mg / kg and glycopyrrolate 0.01 mg / kg .
the sample size was calculated considering a projected difference of 30% between the two groups for airway leak pressures to be significant , at 95% confidence limits , a type 1 error of 0.05 and a power of 80% .
the data were analysed using international business machines corporation spss statistics for windows ( version 22.0 , armonk , ny ) . kolmogorov 
non - parametric data were compared with fisher 's exact test or chi - square test .
data were presented as mean  standard deviation with p < 0.05 as statistically significant .
a total of 122 children were screened , 10 children were excluded due to upper respiratory tract infection and in 12 children the parents refused to participate in the study .
there were no differences in demographic characteristics of patients between the groups as shown in table 1 .
the oropharyngeal leak pressure in i - gel group was 29.5  2.5 ( 95% confidence interval [ ci ] , 2830 ) cmh2 o as compared to 26.1  3.8 ( 95% ci , 2427 ) cmh2 o in plma group ( p = 0.002 ) [ table 2 , figure 2 ] .
insertion time was shorter for i - gel as compared to plma and none of the patients had failures in the insertion of sads .
the number of attempts , ease of insertion of sgds and fibre - optic grading of airway tube were comparable as shown in table 2 .
the quality of initial airway was better in i - gel as compared to plma ( p = 0.018 ) .
pulmonary mechanics including peak airway pressure , mean airway pressure , resistance and compliance were similar in both the groups as shown in table 3 .
success rates of ogt placement and fibre - optic grading were similar in both the groups .
none of the patients experienced any adverse event including intraoperative displacement of sads , gastric insufflation , regurgitation , laryngospasm , bronchospasm and airway obstruction in both the groups .
patient baseline demographic characteristics airway characteristics of supraglottic devices oropharyngeal leak pressure of i - gel versus proseal laryngeal mask airway in paediatric patients undergoing general anaesthesia with controlled ventilation airway parameters after placement of supraglottic airway device
the study exclusively compared oropharyngeal leak pressure of size 2 i - gel with size 2 plma and pulmonary mechanics in paediatric patients under ga with controlled ventilation .
we chose size 2 to bring uniformity in the use of two devices in children aged 26 years weighing 1030 kg as the recommended weight range for the size 2 plma is 1020 kg , whereas it is 1025 kg for the i - gel. the results of our study demonstrated higher leak pressure in size 2 i - gel as compared to size 2 plma. this could be attributed first to the unique non - inflatable cuff of i - gel , which mirrors the perilaryngeal anatomy appropriately .
second , the leak pressure of i - gel appears to improve with time due to thermoplastic material , which forms a more efficient laryngeal seal after warming to body temperature . to obviate this effect , we measured the leak pressure after 5 min of correct placement of i - gel .
currently , some studies show higher leak pressure in i - gel as compared to plma while others show similar leak pressure with both the devices . in a meta - analysis , i - gel
was compared with several types of laryngeal mask airways ( lmas ) in children and authors reported no evidence for differences in rate of insertion at first attempt , insertion time , ease of insertion or gastric tube insertion .
the mean oropharyngeal leak pressure was 3.29 ( 2.254.34 ) cm h2 o higher with i - gel as compared to other lmas . in an another meta - analysis , i - gel
was found to be equally effective and provided a significantly higher leak pressure as compared with plma and clma .
however , in these studies , authors used different sizes of sads and none of these studies compared size 2 i - gel versus plma in paediatric patients undergoing surgery under ga with controlled ventilation . in the present study , time taken for successful insertion of i - gel was less as compared to plma group .
this difference was first due to the less flexible stem in i - gel as compared to plma and second due to the presence of prefilled elastomeric cuff in i - gel allowed to omit the step of inflating the cuff .
this is in contrast with saran et al . , who found comparable insertion times with both the devices
. this might be attributable to different techniques of insertion of plma as saran et al .
the insertion time for i - gel group in the present study was shorter as compared to previous studies .
success rate , number of insertion attempts , ease of sgd and ogt insertion was found to be comparable in both the groups .
the quality of initial airway in the present study was superior in i - gel as compared to plma , which are similar to other studies .
our study showed similar fibre - optic grading in both the groups , which was consistent with other studies .
the present study found similar pulmonary mechanics including resistance , compliance , peak airway pressure and mean airway pressure in both the groups .
saran et al . measured only peak airway pressure and so far no other study has measured pulmonary mechanics in detail . in the present study , there were no significant haemodynamic changes on comparing i - gel and plma and were accordance with published literature .
the present study found similar margin of safety for ventilation in i - gel as compared to plma in patients weighing between 10 and 30 kg receiving ga with positive pressure ventilation .
the novelty of the study is firstly , higher oropharyngeal leak pressure in i - gel as compared to plma which ensures wider safety margin for ventilation in children 26 years weighing 1030 kg and secondly , comparison of pulmonary mechanics in these children on controlled ventilation with size 2 i - gel or plma , which has not been reported earlier in literature .
first , the study involved patients with a normal airway and whether the same outcome can be extrapolated to patients with difficult airway is subject to performance of similar large - scale studies in patients with difficult airway .
second , the blinding was not possible for the anaesthesiologist inserting the device and fibre scope .
third , the airway device insertion was done under muscle relaxant effect , so the results are not necessarily the same for spontaneously breathing and less deeply anaesthetised patients .
fourth , our findings only apply to use of the size 2 devices in children aged 26 years weighing 1030 kg .
size 2 i - gel exhibited superior oropharyngeal leak pressure and quality of airway in paediatric patients with controlled ventilation as compared to same sized plma although the pulmonary mechanics were similar .
 background and aims : i - gel is a newer supraglottic airway device with a unique non - inflatable cuff . 
 we aimed to compare i - gel with proseal laryngeal mask airway ( plma ) in children scheduled for surgery under general anaesthesia ( ga ) with controlled ventilation.methods:this prospective , randomised controlled study was conducted in 100 surgical patients , aged 26 years of american society of anesthesiologists physical status i  ii scheduled under ga . 
 patients were randomly allocated to receive either size 2 i - gel or plma as an airway device . 
 the primary aim was oropharyngeal leak pressure assessed at 5 min following correct placement of the device . 
 secondary outcomes measured included number of attempts , ease of insertion , time of insertion , quality of initial airway , fibre - optic grading and effects on pulmonary mechanics . 
 statistical analysis was done using paired t - test and chi - square test.results:the demographic data were similar in both the groups . 
 the oropharyngeal leak pressure in the i - gel group was 29.5  2.5 cmh2 o as compared to 26.1  3.8 cmh2 o in plma group ( p = 0.002 ) . 
 the time taken for successful insertion in plma was longer as compared to i - gel ( 12.4  2.7 vs. 10.2  1.9 s , p = 0.007 ) . the quality of initial airway was superior with i - gel. the number of attempts , ease of insertion of supraglottic device , insertion of orogastric tube and pulmonary mechanics were similar in both the groups.conclusion:size 2 i - gel exhibited superior oropharyngeal leak pressure and quality of airway in paediatric patients with controlled ventilation as compared to plma although the pulmonary mechanics were similar . 