Electrical contraction of the anal sphincter for intraoperative visualization of anal function

Abstract

Background

Repairing sphincter defects to restore the anal aperture is a cornerstone of surgical treatment in cases of anal preserving surgery. Such procedures are selected and performed according to the surgeons’ experience. In the present study, we aimed to investigate a method for clear and intuitive intraoperative assessment of anal function under general anesthesia.

Methods

This study was conducted in three-month-old female (35 kg) domestic swine (n = 8) under standard general anesthesia. Electrical stimulation of the anal sphincter was performed using prototype electric devices, and then the anal pressure was measured by manometry. We generated an anal dysfunctional model by excising the left puborectalis muscle. Anal function was semi-quantified and visualized using anorectal manometry.

Results

Electrical stimulation with 12.5 mA output current and 15% duty ratio produced maximum anal pressure using the smallest amount of electricity. Histological examination confirmed the safety of the electrical muscular stimulation. Three-dimensional reconstruction of the results from the pressure curves of each sensor-enabled visualization of the functional anal canal. Monitoring using manometry under general anesthesia revealed the recovery of anal function upon suturing the excised puborectalis.

Conclusions

Electrical muscular stimulation feasibly enabled visualization of anal function under general anesthesia in a porcine model.

Keywords:

• Anal function
• intraoperative visualization
• general anesthesia

Acknowledgements

The authors are thankful for the technical assistance provided by Tabuchi Electric Co. Ltd., Osaka, Japan.

Ethical approval

The entire experimental protocol for this study was approved by the institutional animal care and ethical review committee, and was performed according to the animal protocol approved by the Animal Care and Ethical Review Committee of our institution. At the end of the experiment, the animals were euthanized under deep general anesthesia.

Author contributions

Study conception and design: Ohara, Takahashi, Nakajima; acquisition of data: Ohara, Takahashi, Nakajima, Katsuyama; analysis and interpretation of data: Ohara, Takahashi, Katsuyama, Mizushima, Doki, Mori, Nakajima; drafting of manuscript: Ohara, Takahashi, Nakajima; critical revision: Ohara, Takahashi, Katsuyama, Mizushima, Doki, Mori, Nakajima.

Declaration of interest

No potential conflict of interest was reported by the author(s).