Insertion of i-gel™ by the reversed technique improves the success rate and reduces the time taken for its placement: A prospective, randomized, controlled, interventional trial.

BACKGROUND AND AIMS: We hypothesized that the i-gel™ supra-glottic airway can be inserted with relative ease in a reversed manner just like a Guedel's airway.
MATERIAL AND METHODS: A prospective, randomized, controlled interventional trial was conducted on 100 patients to compare reversed insertion of the i-gel™ (Group R) with the conventional insertion (Group C). In Group C, i-gel™ was introduced in a conventional manner, whereas in the Group R, i-gel™ was introduced into the oral cavity with the concavity facing the hard palate. On reaching the oropharynx, the device was rotated 180° and advanced further until it fitted over the larynx. The time of insertion, ease, and placement appropriateness were compared.
RESULTS: All patients completed the study. Better success rate of the first attempt insertion was achieved using the reversed technique (96% vs. 86%), but it was not statistically significant. Mean time required for i-gel™ insertion in Group R was 17.5 ± 6.9 s as compared to 20.8 ± 5.9 s in Group C, which was statistically significant. In Group R, it could be inserted within 20 s in 84% of cases, but only in 62% in Group C. The seal of the i-gel™ was similar in both the groups with the leak volumes (inspired - expired tidal volumes) being similar.
CONCLUSION: Reversed insertion technique for the placement of i-gel™ resulted in appropriate placement with easier insertion and lower placement time than that with the conventional technique.

RCT Entities:   Population Interventions Outcomes

Introduction

Supraglottic airway devices (SADs) are being increasingly used for airway management. SAD fill the niche between the facemask and tracheal tube in terms of anatomical position, ease of insertion and degree of invasiveness. The SAD is placed outside the trachea, yet provide satisfactory airway protection. A large number of SAD are in clinical use and most of them are variants of the laryngeal mask airway (LMA). i-gel™, an innovative second-generation SAD with a thermoelastic hood, is now widely used in anesthesia and resuscitation across the globe. It works in harmony with the patient's anatomy thereby significantly reducing or eliminating compression and displacement trauma.

i-gel™ is conventionally placed with its concave curvature facing the mandible, like the LMA. The insertion by this technique may be hindered in some cases by the tongue, which can obstruct its passage to the pharynx. Reverse insertion of proseal and other SAD has been studied, with the cuff collapsed, but no study of reverse insertion of i-gel™ has been conducted till date. Reverse insertion has not been reported with i-gel™ possibly because its cuff cannot be collapsed. Successful i-gel™ insertion has however been reported by a rotational technique.[1]

We hypothesized that i-gel™ can be inserted, like a Guedel's airway, with its concavity reversed, that is, facing cephalad. This study was planned to assess the feasibility and efficacy of reverse technique of insertion of I-gel SAD and compare it with the conventional technique.

Material and Methods

After the institutional ethics committee approval, a prospective, randomized, controlled, interventional trial was conducted on 100 American Society of Anesthesiologists grade 1–2 adult patients. Inclusion criteria were patients scheduled to undergo surgeries, for duration up to 2 h, using a SAD; adults of both sex (18–50 years); and Modified Mallampati airway grade 1–2. Exclusion criteria were patients for emergency surgery; thoracic, neuro, cardiac, and airway surgery; gastroesophageal reflux disease; obesity; abnormal head, airway, or neck anatomy; and surgery in prone position.

Based on a study on LMA placement, using the reversed technique in the pediatric age group,[2] and taking success rate as the primary outcome, for a power of 80% a sample size of 44 patients was required per group. We took a sample size of 50 in each group considering possible drop outs.

On enrollment, written informed consent was obtained from all participants. Patients were allocated into two Groups, C (conventional) and R (reverse), of 50 patients each, by computer generated randomization. All patients were subjected to routine pre-operative assessment and fasting protocols. All patients were pre-oxygenated by mask for about 3 min. Before induction of anesthesia, patients were administered fentanyl 2 mcg/kg intravenous (IV). The table head end was isolated by a curtain. All recordings of time were done by a person at the foot end of the table. A standardized general anesthesia IV induction with propofol 2–2.5 mg/kg was done. Airway was secured by an appropriate size i-gel™, 3 min after administration of vecuronium 0.1 mg/kg. i-gel™ size was selected based on patient weight, in accordance with manufacturer's guidelines (30–60 kg: i-gel size 3; 50–90 kg: size 4; and >90 kg: size 5). The sides, front, and back of the i-gel™ cuff were lubricated with a water-based jelly before insertion.

In Group C, i-gel™ was inserted with the concavity of the i-gel™ facing the mandible using a pen-holding grip and inserting the device till it fitted over the larynx. In Group R, i-gel™ was introduced into the oral cavity with the concavity of the device facing the hard palate and on reaching the oropharynx, the device was rotated 180° and thereafter advanced further into the laryngopharynx till it fitted over the larynx [Figure 1].

Figure 1

Pictorial illustration of the method of reverse insertion

All airway interventions were performed by a single user, who had experience of about 25 i-gel™ insertions. Appropriate placement of the i-gel™ was confirmed by observing a square wave end-tidal CO2 waveform, auscultation, and movements of the chest wall. In both the groups, the time taken for i-gel™ insertion was taken from the time of stopping face-mask ventilation to the appearance of a square wave capnograph trace after placement of the i-gel™. A nasogastric tube, of appropriate size, was thereafter passed through the gastric tube channel in all cases.

After successful placement of the i-gel™ and confirmation of air entry in the lungs, the lungs were mechanically ventilated, using volume-controlled ventilation, delivered by an Anesthesia Work Station (Aespire 7900, Datex-Ohmeda Inc., Madison, WI, USA) set to deliver a tidal volume of 8 mL/kg; respiratory rate to maintain EtCO2 between 30 and 40 mm Hg; inspiratory-expiratory ratio of 1:2; no peak end-expiratory pressure; and a pressure limit of 30 cmH2O. The total fresh gas flow was maintained at 1 L/min. The difference in the ventilator delivered tidal volume and the expired volume was recorded to determine the airway leak to determine the efficacy of the placement. The peak airway pressures achieved were recorded. Intra-operative monitoring included heart rate, electrocardiography, pulse oximetry, end-tidal carbon dioxide, and noninvasive blood pressure. The hemodynamic and respiratory data recorded immediately after the insertion of i-gel™ was recorded for comparison. Body temperature was maintained using warmed forced air.

Anesthesia was maintained in a routine manner using balanced anesthesia technique with fentanyl, isoflurane, and mixture of oxygen/nitrous oxide with volume controlled ventilation. At the end of the procedure, neuromuscular blockade was reversed and the airway device removed after ensuring adequate recovery. Staining with blood was looked for on the i-gel™. Patients were shifted to the postanesthesia care unit for observation. Patients were followed up for 24 h after surgery for complaints of sore throat (constant pain independent of swallowing), dysphagia (difficulty or pain with swallowing), sore jaw, dysphonia (difficulty or pain in speaking), numbness of tongue or oropharynx, blocked or painful ears, reduced hearing and neck pain. The success rate of insertion of the-gel™ at first attempt was studied as the primary outcome while the time taken for successful insertion of the i-gel was taken as the secondary outcome. Statistical analysis was performed with MedCalc (version 16.1; www.medcalc.org). Data were reported as mean ± standard deviation. Comparison of data, between the groups, was done using Student's t-test for independent samples. For categorical values, Chi-square test was applied. Pearson's Chi-square test, with Yates correction, was applied to determine significance of time interval based distribution of i-gel™ insertion. The value of P < 0.05 was considered statistically significant.

Results

A total of 100 patients were recruited for the study and all completed the study. The demographics of the two groups were similar and are shown in Table 1. Both groups underwent similar surgeries. 75 patients underwent laparoscopic surgeries. The hemodynamics and the ventilation data recorded immediately after the insertion of the i-gel™ were statistically similar in the two groups [Table 2].

Table 1

Demographic data

Table 2

Hemodynamics and respiratory data immediately post i-gel™ insertion

The study data on the insertion of i-gel™ by the two techniques is shown in Table 3. The reverse insertion could be achieved with more ease with better success rate of 1st attempt insertion vis-à -vis the conventional technique (96% vs. 86%), but it was not statistically significant. Mean time required for i-gel™ insertion using the reversed technique was 17.5 ± 6.9 s as compared to 20.8 ± 5.9 s using the conventional technique and the difference was statistically significant. The reversed technique was found to be statistically superior when the groups were compared in terms of time taken for insertion, using Pearson's Chi-square test with application of Yates correction. In 84% of cases in group R i-gel™ could be inserted within 20 s as compared to only 62% of cases in Group C. The fitment of the i-gel™ was similar in both the groups with the leak volumes (inspired – expired tidal volumes) being similar. Placement time was long in some patients in the reverse group with smaller mouth openings.

Table 3

Study data

Sore throat occurred in five patients in the conventional technique group and two patients in the reverse technique group, but the difference was not statistically significant. Blood soiling was seen in five cases in the conventional group and four cases in the reversed group. There were no other complications.

Discussion

Reverse insertion of LMA has been studied with its cuff collapsed. In the reverse technique of LMA insertion, the LMA is inserted with concavity facing the palate. On reaching oropharynx, the LMA is rotated 180° counterclockwise and pushed to its final position. 100% success in pediatric patients has been reported with reverse technique insertion of LMA-Classic vis-à -vis 90% by the standard technique.[2] Brimacombe compared four techniques of LMA-Classic insertion and found the standard technique and 180° rotational techniques superior to partially or fully inflated cuff techniques.[3]

i-gel™ is conventionally inserted with its concave curvature facing the mandible. Its passage from the oral cavity to the pharynx may be obstructed, particularly in children, as the folding of the tongue obstructs its placement.[4] Reverse insertion with i-gel™ has not been tried as its cuff is not collapsible. A case report, however, suggested the reversed technique after the failure of the standard technique.[5] Ghai et al. reported that in children i-gel™ insertion by the reverse insertion technique was easy to use, atraumatic, and could be used, as an alternative, in case the initial attempt by classic technique failed.[6] No randomized controlled trial has however been conducted on the reverse insertion of i-gel™.

The first RCT of i-gel™ insertion, by a nonconventional technique, was published by Kim et al.[1] They introduced i-gel™ into the mouth and rotated it 90° counterclockwise. The i-gel™ was the advanced backward, passing the body of the tongue until resistance was felt at the hypopharynx and it was then re-rotated clockwise to the standard orientation, at which point it returned to the midline. Although the overall success rate was comparable between the two groups, they reported a better first-attempt insertion success rate in the rotation group, shorter insertion time, better airway seal and fewer post-operative complications. We inserted the i-gel™ in a manner similar to the insertion of a Guedel's airway and found similar findings as ease of insertion (placement in the maiden attempt) with the use of this technique. In the reverse technique group, i-gel™ could be inserted in the first attempt in 48 patients compared to only in 43 patients in the study group.

Kumar et al. reported statistically insignificant difference in time duration and number of LMA insertion attempts using different techniques of insertion.[7] However, we found the reverse technique superior in term of both these parameters. In this study, the time taken for reverse insertion was less and insertion was completed in up to 20 s in the reverse group in 84% of patients as compared to 62% in the conventional group. In the reverse group, we could place the i-gel™ in 11 s in 76% of patients as compared to only 60% in the other group.

The rotational technique was found to be easy, with the use of LMA, while negotiating the back of the mouth in children and it had a low complication rate.[8] Ghai et al. recommended that this technique be considered in adults with difficult placement and failures with standard LMA insertion technique.[8] Tongue obstruction, encountered at the time of insertion, was the cause of delayed insertion in the conventional technique in our study.

Kumar et al. reported a lower incidence of trauma using with the use of rotational insertion technique LMA, whereas Kim et al. reported a lower incidence of blood-staining with the rotational technique using i-gel. We too had a lower incidence of blood-staining in the reverse insertion group. We did not encounter any other trauma with both the techniques. The only other complication we had was sore throat, which is known with the use of SAD.

Conclusion

We evaluated the reversed insertion technique for placement of i-gel™ SAD and found that it was associated with easier insertion and lower placement time than that with the conventional technique. The placement of the device was appropriate and there were no complications with the reverse technique.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.