journal club reverse insertion of i gel in overweight and obese patients

Journal club

1. Conventional versus reverse insertion of i ‑gel® in overweight and obese patients – Interventional randomised controlled trial PRESENTER: DR.SINDHU REDDY MODERATOR: DR.AJAY KUMAR

2. INTRODUCTION : Obesity causes a physiologically and sometimes anatomically difficult airway; therefore, managing the airway and oxygenation in obese patients can be challenging. Supraglottic airway devices (SADs) are an excellent alternative to the endotracheal tube (ETT) in securing the airway in obese patients. i -gel® (a second-generation SAD) has been used in obese patients for short- to medium-duration surgical procedures. Due to its high leak pressure in conjunction with easier positioning and faster insertion, it has been proven beneficial in obese patients The current study aimed to evaluate two different insertion techniques for the successful placement of i -gel in the first attempt in overweight and obese patients as measured by an oropharyngeal leak pressure (OLP) METHODS: Patients of the American Society of Anesthesiologists (ASA) physical status I–III posted for elective surgical procedures lasting up to 120 min in a supine position with body mass index (BMI) ≥23 and ≤40 kg/m², classified as overweight, obese class I and II as per the Asian criteria of BMI for nutritional status, were included in the study.

3. One hundred patients were randomised into Group C (n = 50) and Group R (n = 50) by computer-generated random numbers Patients underwent routine preoperative assessment and standard fasting protocols. In the operating room (OR), all patients were positioned in ramped position, standard ASA monitoring was done, and baseline values were recorded. Intravenous (IV) 0.05mg/kg midazolam and 10 mg metoclopramide were administered. After preoxygenation with 100% oxygen for 3–5 min; anaesthesia was induced with IV 2 µg/kg fentanyl and 2–2.5 mg/kg 1% propofol titrated to loss of verbal response. Thereafter, IV 0.5 mg/kg atracurium was administered for neuromuscular blockade. After achieving adequate jaw relaxation, the airway was secured by an appropriately sized i -gel using the technique randomly allocated to that patient. Weight-based selection criteria were used to select the size of i -gel as per the manufacturer’s instructions (size 3: 30–60 kg, size 4: 50–90 kg, size 5: >90 kg). The i -gel cuff was lubricated with a water-based jelly before insertion. An anesthesiologist with an experience in ≥100 SADs insertions and ≥50 i ‑gel insertions performed the procedure Group C, the conventional technique was to insert i -gel, with the concave end of the device facing the mandible in a pen-holding manner and advancing it further until it fitted over the larynx (Brain’s technique).

4. While in Group R, the reverse technique was used to insert i -gel, with the device’s concave end positioning towards the hard palate, rotated by 180° after reaching the oropharynx and further inserting it until it fitted over the larynx ( Guedel’s airway). The time of insertion was recorded from picking up the i -gel till the commencement of mechanical ventilation and the appearance of a square wave capnograph. The maximum time allowed for each attempt was 60 s. A maximum of three attempts were allowed for the insertion of each device. Any change in the device’s size was also considered an attempt. the successful placement of i -gel at the first attempt was confirmed by gently squeezing the reservoir bag and observing visible chest rise, bilateral chest auscultation and appearance of a square wave end-tidal carbon dioxide (EtCO2 ) waveform. The primary outcome was OLP; to measure it, the fresh gas flow was calibrated to 3 l/min, and the circle system’s adjustable pressure-limiting (APL) valve was closed. With no peak end-expiratory pressure, the minimum airway pressure was recorded for the audible gas leak using a stethoscope at the lateral side of the thyroid cartilage. Airway pressures were maintained at ≤40 cmH2 O

5. The patients were put on mechanical ventilation using volume-controlled ventilation set to deliver a tidal volume of 8 ml/kg, respiratory rate to maintain EtCO2 value between 30 and 40 mmHg, inspiratory and expiratory ratio (1:2) and a peak end-expiratory pressure of 5 cm H2 O. Total fresh gas flow was maintained at 1.5 l/min. Anaesthesia was maintained by 4%–6% desflurane in 50:50 oxygen and nitrous oxide. Additional IV 1 μ g/kg fentanyl was given when clinically needed during anaesthesia . Finally, neuromuscular blockade was reversed with an IV injection of 0.04 mg/kg neostigmine and 0.001 mg/kg glycopyrrolate. I-gel was removed after confirming the recurrence of the spontaneous and regular ventilation pattern and sustained head lift for at least 5 s. Patients were shifted to the post- anaesthesia care unit (PACU) for observation. RESULTS: In the present study, 100 patients were recruited; each completed the study Both groups had a statistically significant difference in OLP (P = 0.018). The mean OLP of Group C was 30.46 ± 3.76 mmHg and Group R was 32.12 ± 3.10 mmHg. Both techniques had a high success rate on the first attempt (98%)

6. The mean time of insertion in Group C was 16.42 ± 1.86 s, and in Group R was 13.98 ± 1.97 s. The difference in the mean time of successful i -gel insertion between the groups was statistically significant (P < 0.001). Other manipulations required during the study, like chin lift, jaw thrust, head extension and neck flexion, were minimal and statistically insignificant. None of the patients in each group had intraoperative or postoperative complications like desaturation episodes, dental injury, blood staining, dysphagia, dysphonia or sore throat. The sore throat was graded on NRS; even though the result was statistically significant, none of the patients experienced sore throat (NRS >4). The haemodynamic parameters, like heart rate, blood pressure, oxygen saturation and EtCO2 , remained stable throughout the procedure.

7. Our study found that using the reverse technique produced a significantly higher OLP and better placement than the conventional technique. The study observed a high success rate of i -gel insertion in the first attempt for both techniques Kim et al.,who studied the insertion of i -gel by standard and rotational techniques in non-obese patients. They encountered difficulty because tongue folding resulted in the i -gel embedding at the posterior pharynx during insertion by the conventional technique. Still, they found higher OLP in the rotational technique than in the conventional technique. The present study found higher OLP in the reverse technique than in the conventional technique. Bhardwaj et al. compared three techniques, standard, rotational and reverse, for i -gel. They studied the insertion characteristics, first-attempt insertion and overall success rate in non-obese patients. They found that i -gel insertion with reverse technique resulted in better positioning in the first attempt and overall success rate along with higher leak pressures, but the results were statistically insignificant. The present study was conducted in overweight and obese patient. Reversing the device prevents tongue folding and reduces the resistance between i -gel and the posterior pharyngeal wall. The flexible nature of its cuff and the laryngeal soft tissue in the airway helps push the i -gel cuff more effectively. It leads to a better seal and higher leak pressures between the laryngeal inlet and the i -gel cuff. This could be why the OLP in this study was significantly higher with the reverse technique

8. The study by Prabha et al. compares i -gel insertion for general anaesthesia in non-obese and obese patients using conventional techniques. The study showed higher mean OLP in obese patients than non-obese patients (28.7 vs. 25.8 cmH2 O). OLP depends upon the seal between the cuff and perilaryngeal tissues. The anatomically shaped i -gel is flexible and fits comfortably to the perilaryngeal anatomy. The thermoelastic material of the cuff expands due to the body temperature and provides a reliable seal. The OLP is higher due to excess soft tissue in the oral and pharyngeal cavity. I-gel can be safely used in obese patients as obesity is no more identified as a risk factor for the failure of i -gel insertion, as stated by another study by Theiler et al. I-gel is a rescue device for oxygenation in the difficult airway, although proper seal of i -gel is critical to prevent its displacement. To use i -gel safely in obese patients, the safest and fastest insertion technique is required. There was a comparable difference in the ease of i -gel insertion between the two techniques in the current study. The mean time of i -gel insertion in Group R was significantly lesser than that of Group C (P < 0.001). CONCLUSION: This study demonstrated a relatively higher value of OLP, significantly shorter insertion times and fewer manipulations while using the reverse technique.

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