Changes in hardness and resilience of i‐gel^TM cuffs with temperature: a benchtop study

Abstract

The i-gel is a supraglottic airway with a gel-like thermoplastic cuff. It has been suggested that the seal around the larynx improves following insertion. Perhaps the most intuitive hypothesis proposed for this is that cuff softening occurs during warming from ambient to body temperature. We investigated this using a food industry texture analyser over a wide temperature range. Size 2 and 3 i-gels were secured to a platform within a temperature-controlled water bath, which was in turn mounted on a texture analyser test stand. Both water and i-gel cuff temperatures were recorded. A spherical probe was advanced 4 mm into the surface of each i-gel at a rate of 1 mm.s , then retracted at the same rate while the upward pressure on the probe was recorded. Three runs made at each of the 11 temperatures (10 °C to 60 °C, 5 °C increments) gave 105,864 data points, from which values for hardness (the peak force on the probe at maximum indentation), and resilience (the rate at which the material recovers its original shape) were calculated. Over 10 to 60 °C, the smallest hardness value expressed as a proportion of the largest was 88.2% and 89.8% for size 2 and 3 i-gels, respectively, and for resilience these were 92.8% and 86.2%, respectively. Over room temperature to body temperature range (21-37.4 °C), hardness decreased by 3.15% and increased by 0.47% for i-gel sizes 2 and 3, respectively, whereas resilience values decreased by 1.85% and 2.68%, respectively. Cuff hardness and resilience did generally reduce with warming, but the effect was minimal over temperature ranges that may be encountered during clinical use.

Influence of temperature on volume, weight and density changes of i-gel masks

“…A significant increase in volume (P < 0.001) and weight (3: P = 0.018; 4: P = 0.027; 5: P = 0.006) and a decrease in density (P < 0.001) were observed. A possible explanation for this, besides expansion, is the absorption of fluids, which was also discussed before [5]. The wet milieu, caused by the saliva, could be responsible for this.…”

Does prewarming of i-gel improve insertion and ventilation in anaesthetised and paralysed patients? A prospective, randomised, control trial

“…The improvement in the sealing pressure of the i-gel cuff over time as shown in many studies may be due to the redistribution of the interstitial fluid in the areas around the cuff or due to the interaction between saliva and the cuff material altering its property and allowing it to migrate to a position of better fit. [910]…”

Prewarming i-gel laryngeal mask for mechanical ventilation: a meta-analysis of randomised control trials and trial sequential analysis

“…[9][10][11] Prewarming i-gel laryngeal mask to 42°C would enable the cuff to fit the pharyngeal structure more quickly than if it was stored at room temperature. 5 But Dingley et al 14 evaluated the properties of i-gel cuff over clinical temperature ranges and found that there was a minimal decrease in hardness and resilience with warming.…”

“…But the melting point of i-gel cuff is above 200°C, whether it will soften as it reaches body temperature after insertion remains controversial in clinical practice. 14 So, the efficiency of prewarming i-gel laryngeal mask for mechanical ventilation remains unclear. [15][16][17] This study aims to investigate the efficiency of prewarming i-gel laryngeal mask for mechanical ventilation by meta-analysis and trial sequential analysis (TSA).…”