|Year : 2015 | Volume
| Issue : 2 | Page : 179-182
A comparison of I-gel with the LMA-classic in spontaneously breathing patients
Priyamvada Gupta MD , Alok Kumar, Dharam Das Jethava, Sameer Kapoor, Durga Jethava
Department of Anesthesiology and Critical Care, Mahatma Gandhi Medical College and Hospital, Jaipur, India
|Date of Submission||23-Jun-2014|
|Date of Acceptance||08-Feb-2015|
|Date of Web Publication||8-May-2015|
Pradhan Marg, Malviya Nagar, Jaipur - 302 017
Source of Support: None, Conflict of Interest: None
Laryngeal mask airway (LMA) is a supraglottic airway device (SAD), which was primarily designed to facilitate airway maintenance. Thereafter, many modifications have been made in the SADs, and I-gel is a recent one, which has a unique characteristic of a self-inflatable cuff. It is claimed to be better in terms of ease and success of insertion, risk of complications, etc.
Aims and objectives
The aim of this study was to investigate and compare the insertion characteristics and complication rate of classic LMA with I-gel.
Materials and methods
Eighty patients of American Society of Anaesthesiologists I/II, between 16 and 60 years of age, of either sex were randomly divided into two groups of 40 patients each. In respective groups, classic LMA or I-gel were introduced under spontaneous ventilation. Insertion characteristics such as number of attempts at insertion, ease of insertion, better seal, etc. were studied. Proper positioning was confirmed as per fiberoptic view of the glottis. Patients were continuously monitored and hemodynamic variables were studied at frequent intervals. We also recorded the complications at the time of extubation, if any. Data were statistically analyzed using t-test and the χ2 -test. A P value less than 0.05 was considered statistically significant.
I-gel required less time to insertion (29.32 ± 6.88) compared with cLMA (36.72 ± 7.33 s) (P < 0.05). Airway leak pressure was significantly higher among patients of the I-gel group (26.12 ± 7.41 cm H 2 O) compared with the LMA group (20.77 ± 8.20 cm H 2 O) (P = 0.003). Statistically significant difference was found between the two groups as regards the assessment of patients after removal of the SAD. Fiberoptic view of vocal cords was better in the I-gel group.
Insertion of I-gel was easier and quicker and proper positioning was achieved in more number of patients as compared with classic LMA. Moreover, there were fewer complications noted at the time of removal of the device.
Keywords: classic LMA, I-gel, supraglottic airway device
|How to cite this article:|
Gupta P, Kumar A, Jethava DD, Kapoor S, Jethava D. A comparison of I-gel with the LMA-classic in spontaneously breathing patients. Ain-Shams J Anaesthesiol 2015;8:179-82
|How to cite this URL:|
Gupta P, Kumar A, Jethava DD, Kapoor S, Jethava D. A comparison of I-gel with the LMA-classic in spontaneously breathing patients. Ain-Shams J Anaesthesiol [serial online] 2015 [cited 2021 Jan 28];8:179-82. Available from: http://www.asja.eg.net/text.asp?2015/8/2/179/156672
| Introduction|| |
The conventional method of securing the airway is endotracheal intubation, which involves laryngoscopy and its consequences. This process involves distortion of normal anatomy  and is also associated with extensive sympathetic stimulation leading to tachycardia, hypertension, and arrhythmias  . Alternative methods of securing airway have also been developed mainly using supraglottic airway devices (SADs). One such device was laryngeal mask airway (LMA) introduced by Dr Archie Brain in 1983. It was primarily developed to be used for securing airway and ensuring ventilation in emergency situations, especially by untrained personnel  . However, it was found to be useful in many patients for administering general anesthesia. It has even been used as a conduit for endotracheal intubation. LMA-classic is the most commonly used supraglottic device. LMA-classic is also included in difficult airway society guidelines for unanticipated difficult intubation  . However, cuff of the device needs to be inflated to create a seal around perilaryngeal tissues, which can cause tissue distortion , . Cases of venous compression and nerve injury have also been reported , . Depending upon the material from which the cuff is made, they can absorb anesthetic gases, which can lead to increased mucosal pressure  .
Many modifications have been made and various SADs have been developed. I-gel is a relatively new single-use SAD, which does not have an inflatable cuff  . It is made from a soft, gel-like, transparent thermoplastic elastomer (styrene ethylene butadiene styrene), which creates a noninflatable seal that is a mirror impression of the supraglottic anatomy  . I-gel has several other useful design features, including a gastric channel, an epiglottic ridge, and a ridged flattened stem to aid insertion and reduce the risk of axial rotation  . The stem of I-gel is less flexible compared with the LMA-classic and has an integral bite  . I-gel has also been used in rescue airway management and as a conduit of tracheal intubation  .
We performed this study to evaluate the clinical performance of I-gel in adult patients, by comparing their efficacy with the LMA-classic in terms of insertion time, sealing pressures, glottis view through fibreoptic scope, and incidence of complications.
| Materials and methods|| |
This study was conducted at Mahatma Gandhi Medical College and Hospital, Jaipur, Rajasthan, India. After obtaining approval from the institutional ethical committee, patients of American Society of Anaesthesiologists (ASA) physical status I/II requiring general anesthesia for surgery of duration less than an hour were recruited. Informed, written consent was obtained in all cases. Using the chit method, patients were randomized into two groups of 40 patients each, to receive LMA-classic or I-gel for airway management during short duration surgeries. Exclusion criteria were as follows: patients under 18 years of age, presence of risk of aspiration (nonfasted, gastroesophageal reflux, BMI >35 kg/m 2 , obstetric patients), presence of potential difficult airway (mouth opening <2 cm, Mallampati class 4, limited neck extension, previous difficult tracheal intubation), presence of preoperative sore throat, and limited access to patients' airway during surgery. The size of the device was decided by anesthetist based on the patient's body weight and manufacturer's recommendation: size 3 for patients weighing between 30 and 50 kg, size 4 for those between 50 and 90 kg, and size 5 for patients weighing more than 90 kg. In the LMA-classic group, the size 3 cLMA was used for patients weighing less than 50 kg, size 4 for those weighing 50-70 kg, and size 5 for patients weighing more than 70 kg.
We used the Datex-Ohmeda Aestiva/5 anesthesia machine (GE Healthcare, Datex Ohmeda Inc. 3030 Ohmeda drive, Madison WI, USA ) with its built-in pressure gauge for study. Intravenous access was obtained and standard monitoring (noninvasive blood pressure, oxygen saturation, ECG and end tidal CO 2 ) was instituted. Premedication was carried out with an injection of 0.005 mg/kg of glycopyrrolate and 2 mcg/kg of fentanyl. Induction was carried out with an injection of 2-3 mg/kg propofol in slow incremental doses until adequate depth of anesthesia was achieved as assessed by loss of eyelash reflex. Allocated device was then inserted by an experienced investigator and maintained with nitrous oxide and oxygen (50: 50) and isoflurane 0.5-1.5 MAC. All patients in either group were kept on spontaneous ventilation.
Each device was lubricated with a water-based agent and inserted according to the manufacturer's recommendations, in a deflated condition, with the patient's head in the neutral position. As per manufacturer's recommendations, size 3 LMA was inflated with 30 ml air and size 4 LMA was inflated with 45 ml air. It was fixed in neutral position. The time to successful insertion was measured from the moment the facemask was removed until the first capnography upstroke after insertion of the device. If chest movement was not adequate, or the capnography wave was not square-shaped after insertion, ventilation was considered inadequate and manipulations were allowed in the following sequence: gentle pushing or pulling of the device; changing head position by extension or flexion; and jaw thrust. After confirming adequate ventilation, the device was fixed in place in neutral position with tape. The number of attempts at successful insertion and time taken were noted.
Hemodynamic parameters were continuously monitored and recorded before insertion, after insertion, and 1, 2, and 5 min after insertion. Airway sealing was examined by measuring oropharyngeal leak pressure and peak inspiratory pressure at a tidal volume of 10 ml/kg using pressure controlled ventilation. To determine the leak pressure, the expiratory valve was closed and a fresh gas flow of 3 l/min was set until equilibrium was reached (airway pressure was not allowed to exceed 40 cm H 2 O). Keeping the flow rate at 3 l/min, the airway pressure is gradually increased by altering the pressure on the reservoir bag during ventilation. The pressure at which an audible noise is detected using a stethoscope placed just lateral to the thyroid cartilage is the airway leak pressure.
A flexible fiberoptic scope was then used to view and record the anatomical alignment of the device in relation to the structures around glottis. The images were recorded as follows: grade 1, clear view of the vocal cords; grade 2, only arytenoids visible; grade 3, only epiglottis visible; and grade 4, larynx not visible  .
After the end of surgery, the device was removed at a depth of anesthesia when an adequate respiratory pattern was observed. Throughout anesthetic maintenance and recovery, the occurrence of any complications, including hypoxia, airway obstruction, suspicion of laryngospasm, sustained coughing, vomiting, blood stains on the removed device, and postoperative sore throat or dysphagia were recorded.
The primary endpoint of the study was the success rate of insertion at first attempt. Secondary endpoints were number of attempts at insertion, complications, and leak pressures during anesthesia.
Statistical data analysis
The sample size was calculated to detect a 10% difference in success rate in insertion between devices with a type-1 error of 0.05 and a power of 90%, requiring 25 patients per group. We recruited 40 patients for each group to accommodate dropouts. Quantitative data were presented as mean ± SD and were analyzed using t-test, whereas qualitative data were presented as number of patients (n) and analyzed using the χ2 -test. A P value less than 0.05 was considered significant.
| Results|| |
The demographic data were statistically similar between the two groups, as shown in [Table 1]. In this study, both LMA-classic and I-gel were easy to insert and did not require laryngoscope. Insertion was difficult in six patients in the I-gel group and in eight patients in the LMA group and required second attempt and jaw stabilization by an assistant. Successful insertion was achieved in first attempt in 87.5 and 77.5% of patients of the I-gel and LMA groups, respectively, but was not statistically significant (P = 0.986) ([Table 2]). The mean time to insertion was 29.32 ± 6.88 s in the I-gel group, whereas it was 36.72 ± 7.33 s in the cLMA group. It was highly significant, with a P value of 0.000.
Airway leak pressure was significantly higher among patients of the I-gel group (26.12 ± 7.41 cm H 2 O) compared with 20.77 ± 8.20 cm H 2 O in the LMA group (P = 0.003). The mean arterial pressure, heart rate, and arterial oxygen saturation (SpO 2 ) were comparable in all patients after insertion of respective devices. Statistically significant difference was found between both the I-gel and cLMA groups as regards the assessment of patients after removal of the SAD, evidencing that I-gel had a lower incidence of complications such as cough, sore throat, blood staining, etc. ([Table 3]). Fiberoptic view of vocal cords was better in the I-gel group ([Table 4]).
| Discussion|| |
This study demonstrates that first time insertion success rate and the overall success rate between I-gel and LMA-C is comparable (P = 0.986). However, I-gel has advantages over LMA-classic in terms of shorter insertion time, better fibreoptic view of glottis, and adequate airway seal pressure. I-gel was inserted with ease and comparatively faster compared with cLMA, showing that there is less need for skill and learning. Shorter insertion times for the I-gel group compared with the LMA-classic group is probably because there is no need to inflate the cuff in case of I-gel.
Airway seal was better with I-gel than with cLMA as evidenced by seal pressures. The efficacy of seal depends on the fit between the glottis and the oval-shaped cuff or gel of the supraglottic device  . I-gel is made of a thermoplastic elastomer with a soft durometer material, which is designed to anatomically fit the perilaryngeal and hypopharyngeal structures without the use of an inflatable cuff. This may explain the reason for the improved seal  . Lee and colleagues demonstrated that cuff pressure significantly affects the sealing of airway; thus I-gel is more convenient to use when compared with the LMA-classic.
I-gel also provides a good fiberoptic score, and similar results were also reported in various studies  . Improved glottic view confirms that I-gel forms a good seal at laryngeal structures and ensures better ventilation and passage of a tracheal tube. In recent times, I-gel has been recommended as a conduit for tracheal tube insertion in cases of difficult intubation. I-gel has been proved to be a better alternative in various other studies also  . The incidence of complications is also low, which may be due to less pressure effects.
There are however some limitations to our study. As data were collected in an unblinded manner, presence of some bias is possible. All patients were of ASA grade I/II and none had anticipated difficult intubation, as evidenced by mallampati scores; this however does not represent general population. Moreover, the investigator had less prior experience with I-gel as compared with cLMA.
There is further scope to study the ease of intubation through I-gel and compare with LMA fast track.
| Conclusion|| |
To summarize, our study demonstrates that I-gel is a better SAD with few complications in comparison with cLMA. It is easier and quicker to insert and provides better fiberoptic view of the glottis.
| Acknowledgements|| |
Conflicts of interest
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[Table 1], [Table 2], [Table 3], [Table 4]