The lower esophageal sphincter is a bothersome little junction that so often fails to do its job: either it’s too loose and burps up hot acid after each meal, or it’s too tight and won’t let anything down. Although we jam all sorts of devices down there to determine the need for surgical intervention, it’s hard to get a clear picture of the entire sphincter’s behavior. The EndoFlip is a new device that was shown off at the emerging technologies session of SAGES 2008 and is claimed to make measurements of LES tone much more accurate and informative.

Manometry, which is currently the most popular tool to assess sphincter tone, involves placement of a pressure-sensitive catheter at various points along the esophagus to measure tone when patients swallow. The EndoFlip, in contrast, measures cross-sectional area all along the esophageal sphincter in response to a controlled level of pressure. Because a partially open and completely open sphincter both generate very little pressure, cross-sectional area appears to be a more sensitive measure:

The EndoFlip itself consists of a catheter with numerous electrodes surrounded by a bag that fills with saline at a constant rate.

Each electrode gives an independent measurement of cross-sectional area, and these data are used to create a three-dimensional image of the sphincter’s response to a given pressure load.

The electrode measurements can also be plotted against time to show how the various parts of the sphincter respond to changes in pressure. In the below graph, CSA stands for cross-sectional area, which is being measured at eight different electrodes while saline is infused into the bag. 

These measurements are useful not only when determining the need for surgical intervention, but also when assessing the success of those interventions. The below image, for example, shows a patient’s LES responding to pressure before and after a fundoplication.

The three-dimensional images can even be animated to show dynamic changes in sphincter tone as more pressure is added to the bag, as shown in this video:

Although the EndoFlip was discussed primarily in the context of GERD, it’s clear the device could be used to measure tone at any sphincter. We don’t yet have the details on when the EndoFlip will be made available, but we’ll keep you posted. In the meanwhile, those interested in the technical details should take a look at this paper.