Functional Lumen Imaging Probe (FLIP) is a test used to evaluate the function of the
esophagus
The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...
, by measuring the dimensions of the esophageal lumen using
impedance planimetry Planimetrics is the study of plane measurements, including angles, distances, and areas.
History
To measure planimetrics a planimeter or dot planimeter is used. This rather advanced analog technology is being taken over by simple image measurement ...
. Typically performed with sedation during
upper endoscopy
Esophagogastroduodenoscopy (EGD) or oesophagogastroduodenoscopy (OGD), also called by various other names, is a diagnostic endoscopic procedure that visualizes the upper part of the gastrointestinal tract down to the duodenum. It is considered ...
, FLIP is used to evaluate for
esophageal motility disorders
An esophageal motility disorder (EMD) is any medical disorder causing difficulty in swallowing, regurgitation of food and a spasm-type pain which can be brought on by an allergic reaction to certain foods. The most prominent one is dysphagia.
E ...
, such as
achalasia
Esophageal achalasia, often referred to simply as achalasia, is a failure of smooth muscle fibers to relax, which can cause the lower esophageal sphincter to remain closed. Without a modifier, "achalasia" usually refers to achalasia of the esoph ...
,
diffuse esophageal spasm
Diffuse esophageal spasm (DES), also known as distal esophageal spasm, is a condition characterized by uncoordinated contractions of the esophagus, which may cause difficulty swallowing (dysphagia) or regurgitation. In some cases, it may cause sym ...
, etc.
Procedure
FLIP is most often performed immediately following upper endoscopy (EGD).
EGD helps to rule out a mechanical obstruction as a cause for symptoms, and also provides an estimation on the distance from the incisors to the EGJ.
FLIP uses impedance planimetry to measure the cross sectional area of the esophageal lumen.
The FLIP device consists of a balloon that encases a catheter with multiple pairs of impedance electrodes. Two catheter configurations are available, which are 8 cm and 16 cm in length. The 8 cm catheter includes 16 sensors spaced 0.5 cm apart, and is used to evaluate esophagogastric junction (EGJ) distensibility and CSA.
Alternatively, the 16 cm catheter has 16 sensors spaced 1 cm apart, and may be used to evaluate contractility via secondary peristalsis patterns, in addition to evaluating the esophagogastric junction (EGJ).
Following upper endoscopy, the balloon is inserted into the esophagus and the balloon is distended with a fluid with known properties (e.g. conductivity and volume).
Each electrode then measures impedance, and a single pressure sensor at the end of the device measures pressure within the balloon.
Results
The distensibility index (DI) is the most studied and most helpful result obtained with FLIP testing.
The normal DI ranges from 3.1 to 9.0 mm2 per mmHg.
As the balloon is distended, the results of secondary esophageal secondary contractions may be seen via FLIP panometry.
Possible results may include: repetitive anterograde contractions (a normal finding), repetitive retrograde contractions (abnormal), absent contractility, and other abnormalities.
Indications
FLIP may be used for several indications to evaluate esophageal symptoms, such as dysphagia, chest pain, or regurgitation, or to assess response to treatment. FLIP is used to evaluate for esophageal motility disorders, such as
achalasia
Esophageal achalasia, often referred to simply as achalasia, is a failure of smooth muscle fibers to relax, which can cause the lower esophageal sphincter to remain closed. Without a modifier, "achalasia" usually refers to achalasia of the esoph ...
,
diffuse esophageal spasm
Diffuse esophageal spasm (DES), also known as distal esophageal spasm, is a condition characterized by uncoordinated contractions of the esophagus, which may cause difficulty swallowing (dysphagia) or regurgitation. In some cases, it may cause sym ...
, etc.
FLIP may be used as a complementary or alternative to esophageal manometry for evaluating esophageal outflow obstructive disorders, including achalasia. FLIP may be used as a complementary test for barium esophagram for evaluating esophageal outflow obstructive disorders. FLIP may be used to assess the effect of treatment for achalasia.
FLIP is recommended to further evaluate suspected
esophagogastric junction outflow obstruction
Esophagogastric junction outflow obstruction (EGJOO) is an esophageal motility disorder characterized by increased pressure where the esophagus connects to the stomach at the lower esophageal sphincter. EGJOO is diagnosed by esophageal manometry. H ...
(EGJOO) where the manometry is normal or borderline.
FLIP measurements may be used to guide intraoperative reflux surgery, or to assess the degree of fibrostenotic disease from eosinophilic esophagitis.
FLIP may be used to guide endoscopic dilation of esophageal strictures.
While recommendations exist for its use, the evidence supporting the use of FLIP is of very low quality and further research would be useful in more clearly defining its role.
History
Early development of impedance planimetry for evaluating the gastrointestinal tract began in the 1980s.
FLIP was first developed with a short balloon catheter, which measures distension across the esophagogastric junction.
A second generation device was later released, which measures secondary peristalsis proximal to the EGJ.
See also
*
Esophageal motility disorder
An esophageal motility disorder (EMD) is any medical disorder causing difficulty in swallowing, regurgitation of food and a spasm-type pain which can be brought on by an allergic reaction to certain foods. The most prominent one is dysphagia.
Es ...
*
Esophageal motility study
An esophageal motility study (EMS) or esophageal manometry is a test to assess motor function of the upper esophageal sphincter (UES), esophageal body and lower esophageal sphincter (LES).
Indications
An EMS is typically done to evaluate suspecte ...
References
{{Digestive system procedures
Diagnostic gastroenterology
Digestive system procedures
Endoscopy
Medical tests