A Simpler Method for Choosing Adult i-gel Size: An Evaluation of Real-World Prehospital Data

Objective

The i-gel supraglottic airway device is commonly used in the United States and worldwide for prehospital airway management. Previous research has suggested that a sex-based method of size selection (4.0 for female patients, 5.0 for male patients) is superior to a weight-based method in patients undergoing elective anesthesia. Our objective was to compare a sex-based i-gel size selection strategy to a weight-based strategy using real-world prehospital data.

Methods

The ESO Data Collaborative 2018-2022 dataset was used. All initial i-gel insertion attempts in patients > 18 years of age were evaluated for inclusion. Insertion attempts were excluded if age, sex, weight, success, or device size was not documented. Airway attempts were classified as being consistent with a weight-based sizing method if the i-gel size was 3.0 and the patient was less than 50 kg, the i-gel size was 4.0 and the patient was 50-90 kg, or the i-gel size was 5.0 and the patient was greater than 90 kg. Airway attempts were classified as being consistent with a sex-based sizing method if the i-gel was a 4.0 and the patient was a female or if the i-gel was a 5.0 and the patient was a male. Logistic regression was used to compare the rate of insertion failure on the first attempt for the group placed in alignment with the weight-based but not sex-based method to the group placed in alignment with the sex-based but not weight-based method.

Results

After application of exclusion criteria, 39,867 initial i-gel insertion attempts were included. The overall rate of failure was 6.5% (2,585/39,867). Among the total number of insertion attempts, 9,637 (24.2%) were consistent with both the weight-based and sex-based sizing method, 10,738 (26.9%) were consistent with the weight- but not sex-based sizing method, 5,527 (13.9%) were consistent with the sex- but not weight-based method, and 13,965 (35.0%) were consistent with neither method. The rate of unsuccessful i-gel placement was similar when i-gel devices were placed in alignment with a sex-based size selection method in comparison to i-gel placement in alignment with a weight-based selection strategy (6.0 vs. 6.4%). Logistic regression analysis did not reveal a significant difference between groups (OR: 1.08 [0.95, 1.23]).

Conclusion

The use of a sex-based method of i-gel size selection may be equivalent with respect to the rate of unsuccessful i-gel placement on the first attempt in comparison to a weight-based method.