Endoluminal Functional Lumen Imaging Probe (EndoflipTM): understanding the technology and its potential uses

The EndoflipTM is an innovative technique that uses impedance planimetry technology to assess the distensibility of gastrointestinal organs.

Despite being developed in 2009, its use is still restricted to research environments due to high costs and the need for more evidence for better standardization of the method.

It consists of a catheter that has at its distal end a distensible balloon of 8 or 16 cm (Figures 1 and 2). In this balloon, there are 16 pairs of impedance planimetry sensors, which are capable of measuring the cross-sectional area of a plane of the organ (planimetry) using the electrical resistance (impedance) of the fluid in the balloon.

At the distal end of the catheter, there is also a pressure transducer, which is responsible for measuring the pressure inside the balloon. Thus, by dividing the cross-sectional area by the pressure, we can determine the Distensibility Index in response to volume-controlled distension.

Figure 1: Representation of the EndoflipTM monitor (Su B et al, 2020).
Figure 2: Representation of the EndoflipTM catheter taking measurements in the lower esophageal sphincter (Hirano et al, 2017).

Most of the studies with EndoflipTM have been carried out for esophageal evaluation. For this, the catheter is introduced with the patient sedated, usually after upper digestive endoscopy.

With the introduction of EndoflipTM 2.0 in 2017, a topography system was also associated, which allows the evaluation of esophageal motility (whether absence of waves, whether abnormal retrograde contractions or normal anterograde contractions) – Figure 3.

Figure 3: Unaltered exam, presenting esophagogastric junction with normal distensibility and normal anterograde contractions (Dorsey YC et al, 2020).
Figure 3: Unaltered exam, presenting esophagogastric junction with normal distensibility and normal anterograde contractions (Dorsey YC et al, 2020).

The potential applications of the method are:

1. Evaluation of dysphagia and achalasia

  • Highlight in those patients with clinical suspicion of achalasia, but diagnostic doubt due to normal relaxation of the esophagogastric junction (EGJ) in manometry exam;
  • Usefulness in patients who cannot perform manometry due to not tolerating the discomfort of the probe (EndoflipTM is performed sedated);
  • Distensibility index of the EGJ > 3 mm2/mmHg and anterograde contractions suggest normality (Figure 3);
  • Distensibility index £ 1.6 mm2/mmHg of the EGJ, as well as absence of contractions (figure 4) or repetitive retrograde contractions (figure 5) suggest achalasia.
  • In cases of manometric diagnosis of EGJ flow obstruction, the Distensibility Index of the EGJ < 2 mm2/mmHg is associated with better symptomatic response to therapies similar to achalasia, while values > 3 mm2/mmHg are favorable to conservative follow-up.
Figure 4: Esophagogastric junction with reduced distensibility and absence of contractions, suggesting Type I Achalasia (Dorsey YC et al, 2020).
esophagogastric-junction-with-reduced-distensibility-type-3-achalasia.jpg
Figure 5: Esophagogastric junction with reduced distensibility and repetitive retrograde contractions, suggesting Type III Achalasia (Dorsey YC et al, 2020).

2. Intraoperative use to guide adjustments in myotomies and fundoplications

  • In myotomies, values of Distensibility Index of the EGJ between 4.5 and 8.5 mm2/mmHg suggest better results (Figure 6);
  • In fundoplications, values of Distensibility Index of the EGJ between 2 and 3.5 mm2/mmHg were associated with lower index of dysphagia and reflux after procedure.
Figure 6: Distensibility Index of the Esophagogastric Junction before and after myotomy in a patient with achalasia (Su B et al, 2020)

3. Evaluation in eosinophilic esophagitis

  • Identify esophageal distensibility, in order to identify fibrostenotic narrowings that are not always well evaluated by endoscopy.
  • Potential benefit in patients who persist with dysphagia despite histological remission, possibly guiding possible dilations.

4. Other potential uses

  • Evaluate pyloric distensibility in patients suspected of gastroparesis
  • Evaluate anal canal in patients with incontinence.

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How to cite this article

Lages RB., Endoluminal Functional Lumen Imaging Probe (EndoflipTM): getting to know the technology and its potential uses. Gastropedia, 2022. Available at: https://gastropedia.com.br/gastroenterologia/esofago/endoluminal-functional-lumen-imaging-probe-endofliptm-conhecendo-tecnologia-e-seus-potenciais-usos/

Bibliographic References

  1. Dorsey YC, Posner S, Patel A. Esophageal Functional Lumen Imaging Probe (FLIP): How Can FLIP Enhance Your Clinical Practice? Dig Dis Sci 2020. Online ahead of print. doi:10.1007/s10620-020-06443-8.
  2. Hirano I, Pandolfino JE, Boeckxstaens GE. Functional Lumen Imaging Probe for the Management of Esophageal Disorders: Expert Review From the Clinical Practice Updates Committee of the AGA Institute. Clin Gastroenterol Hepatol 2017;15:325–34. doi:10.1016/j.cgh.2016.10.022.
  3. Su B, Novak S, Callahan ZM, Kuchta K, Carbray JA, Ujiki MB. Using impedance planimetry (EndoFLIPTM) in the operating room to assess gastroesophageal junction distensibility and predict patient outcomes following fundoplication. Surg Endosc 2020;34:1761–8. doi:10.1007/s00464-019-06925-5.
  4. Su B, Dunst C, Gould J, Jobe B, Severson P, Newhams K, et al. Experience-based expert consensus on the intra-operative usage of the endoflip impedance planimetry system. Surg Endosc 2020. doi:10.1007/s00464-020-07704-3.