Teleflex | LMA - Better by Design

Authors

Publication

Br J Anaesth 2009; 102 (1): 135-139.

Summary

• A study to compare the oesophageal seal of the LMA Classic™, LMA ProSeal™ and i-gel™ supraglottic airway devices in human cadavers
• The LMA Classic™ and LMA ProSeal™ devices withstood a significantly higher oesophageal pressure than the i-gel™ in cadaver models
• The LMA ProSeal™ and i-gel™ devices were associated with a rapid and complete drainage of gastrointestinal fluid through the oesophageal lumen in cadaver models, and their use may prevent tracheal aspiration

Objectives:

• To compare the oesophageal seal of the LMA Classic™, LMA ProSeal™ and i-gel™ supraglottic airway devices in human cadavers

Method:

• This study was undertaken using tracheae and oesophagi dissected from eight unfixed human cadavers
• An investigation of the oesophageal seal of the devices was undertaken by connecting the exposed ends of the oesophagi to a water column in the form of a vertical flexible hose
• A slow increase in oesophageal pressure was simulated by adding 5 cm of water every 10 seconds to a maximum pressure of 130 cm H₂O
  • A loss of oesophageal seal occurred when the column height no longer increased and fluid was detected in the lumen of the device
• A fast increase in oesophageal pressure was simulated by applying an immediate pressure of 130 cm H₂O (achieved by filling the column to 130 cm H2O when the hose connected to the end of the oesophagus was clamped and then subsequently removed)
  • The level of the column 1 minute after removing the clamp was considered the oesophageal seal
  • Each test was conducted on ten occasions for each device and on each cadaver in a randomised manner

Results:

• The age and body weight of the 5 female and 3 male donors ranged from 67-84 years and 60-100 kg, respectively
• All three devices were successfully inserted into the cadaver models
  • In order to undertake functional testing, it was necessary that the LMA Classic™ and LMA ProSeal™ be placed again in one case each and that the i-gel™ be placed again in two cases
• During the slow pressure increase, the maximum oesophageal pressure achieved before the occurrence of a leak was highest with the LMA ProSeal™ and lowest with the i-gel™ (Figure 1)

Figure 1. Median maximum oesophageal pressure achieved with the LMA Classic™, LMA ProSeal™ and i-gel™ during a slow increase in oesophageal pressure

• During the fast pressure increase, the oesophageal pressure 1 minute after the maximum pressure had been applied was highest with the LMA ProSeal™ and lowest with the i-gel™ (Figure 2)
• It was possible to rapidly and completely drain all of the oesophageal fluid through the lumina of the LMA ProSeal™ and i-gel™ devices, without any tracheal aspiration

Figure 2. Median oesophageal pressure with the LMA Classic™, LMA ProSeal™ and i-gel™ 1 minute after a fast increase in oesophageal pressure

Conclusions:

• The LMA Classic™ and LMA ProSeal™ devices withstood a significantly higher oesophageal pressure (as demonstrated by a better oesophageal seal) than the i-gel™ in cadaver models
• The rapid and complete drainage of gastrointestinal fluid through the lumen of the LMA ProSeal™ and i-gel™ devices may result in the prevention of tracheal aspiration