The Application of Remote-Controlled High-Definition Capsule Endoscopy in Canine Bladder Examination

Summary

Here, we present a protocol for examining the canine bladder using a high-definition capsule endoscope, surgically implanted and maneuvered to capture images of the bladder wall and urination dynamics. The procedure offers insights for developing precise urodynamic studies.

Abstract

This study investigated the feasibility and potential applications of capsule endoscopy for bladder examination using a canine model. Three adult male Beagle dogs underwent surgical implantation of capsule cystoscopes and were divided into three groups, each group with one Beagle: Group A (Beagle A) remained in a fixed supine position for 8 h, Group B (Beagle B) moved freely for 8 h, and Group C (Beagle C) had manually adjusted positions (prone, supine, squatting) for 20 min each. The implanted capsule endoscopes functioned successfully in all dogs. Group A primarily captured images of the bladder base (6 h 27 min). Group B acquired images of the bladder neck and base (7 h 12 min), including dynamic visualization of the bladder neck, prostatic fossa, and external urethral sphincter during natural urination. Group C yielded images of the bladder neck, base, and apex (56 min). The findings of this study demonstrate the ability of capsule endoscopy to provide dynamic, high-quality images of the canine bladder wall and suggest its potential for developing accurate and urodynamic assessments.

Introduction

Transurethral cystoscopy, a common diagnostic tool in urological surgery, is widely used clinically not only as a reliable method for diagnosing bladder cancer but also as an important means for treatment and postoperative follow-up¹. However, traditional cystoscopic examination, whether rigid or flexible, often causes discomfort to patients and may lead to complications such as urethral damage and retrograde infection². Additionally, traditional urodynamic tests, by disturbing the normal physiological activity of the urinary tract and the mental and psychological activities of patients, inevitably introduce certain errors in the results^3,4,5. Thus, the development of a miniaturized, comfortable, blind-spot-free, and more accurate diagnostic method represents a future direction for the advancement of cystoscopy.

Capsule endoscopy, also known as wireless endoscopy, has been extensively applied in gastrointestinal examinations, offering benefits such as convenience, painlessness, absence of cross-infection, and no disruption to normal patient activities. The painless acquisition of comprehensive gastrointestinal tract imaging data through capsule endoscopy has become a standard method^6,7,8. Given that the bladder is a hollow organ connected to the external environment through the urethra, a capsule of appropriate size can be introduced into the bladder via the urethra.

Based on this, we propose the concept of a capsule cystoscope and explore its advantages and potential applications as a novel diagnostic tool through animal experiments, thereby providing new insights for the future development of capsule endoscopy technology. In this context, we hypothesize that the capsule cystoscope can obtain clear intravesical images and capture dynamic changes of different structures during the physiological urination process, providing insights for the development of more accurate urodynamic testing. This could potentially minimize patient discomfort in the future and expand the indications for cystoscopic examinations.

Protocol

This research was approved by the Medical Ethics Committee of the Affiliated Kunshan Hospital of Jiangsu University, strictly adhering to the Guidelines for the Ethics and Welfare of Experimental Animals. The ethical approval document number is 2021-06-008-K01.

1. Subjects

1. Use three healthy adult male Beagles for the study. Randomly divide them into groups A, B, and C, with one dog per group.
2. Inclusion criteria: Include animals that are 24 months old, approximately 12 kg in weight, and are free from cardiovascular, renal diseases, and other chronic conditions.
3. Exclusion criteria: Exclude animals that have undergone any medicinal treatment received within a week before the experiment.

2. Experimental materials

1. Conduct bladder examinations using a capsule endoscopy system, including a high-definition intelligent capsule, an image recorder, and a workstation. The capsule endoscope measures approximately 11 mm × 25 mm, captures images at 2 frames per second (FPS), operates for 8-10 h, and can transmit about 60,000 frames.

3. Experimental design

1. Preoperative preparation
   1. Fast the Beagle dog for 8 h and withhold water for 2 h prior to surgery.
   2. Administer ampicillin (22 mg/kg) subcutaneously 30 min before surgery as a prophylactic antibiotic.
   3. Remove hair from the medial aspect of the left forelimb and the lower abdomen using clippers. Clean the surgical site with sterile saline and dry with sterile gauze. Disinfect the surgical site with povidone-iodine.
   4. Place a 20 G intravenous catheter in the cephalic vein of the left forelimb. Secure the Beagle dog to the operating table.
2. Anesthesia
   1. Monitor vital signs. Administer dexmedetomidine hydrochloride (0.005 mL/kg) intravenously for sedation, followed by propofol (1.0 mL/kg) for induction of anesthesia.
   2. Insert an 8 mm endotracheal tube into the trachea using a laryngoscope. Confirm correct placement by auscultation and secure the tube with tape.
   3. Connect the Beagle dog to a veterinary anesthesia machine and maintain anesthesia with 1.5% to 3% isoflurane in oxygen via inhalation.
3. Capsule endoscope implantation
   1. Place the Beagle dog in a supine position and position the image recorder nearby.
   2. Disinfect the lower abdomen three times with povidone-iodine and apply sterile surgical drapes.
   3. Make a 10 cm longitudinal incision adjacent to the penis using a #3 scalpel handle and a #10 blade. Incise the skin and subcutaneous tissues and bluntly dissect the abdominal muscles. Lift and retract the peritoneum using two hemostats.
   4. Locate the bladder and gently grasp it with atraumatic forceps. Lift and secure the bladder to prevent damage.
   5. Make a 1 cm incision on the bladder.
   6. Remove the capsule endoscope. Connect the image recorder to the workstation using the dedicated universal serial bus (USB) cable, then press and hold the power button on the image recorder for 3 s to power it on.
   7. Double-click the OMOM Ove icon on the workstation desktop. Enter the username and password to log in to the workstation software. Click Add Patient and enter the information for the Beagle, then click Save.
   8. In the Patient Information section of the workstation software, enter the capsule endoscope serial number and channel number to activate the capsule. Click Next, then click Create New Case. When prompted to format the device, select Yes.
   9. Check that the capsule endoscope is functioning properly. Click Real-time View to display the capsule endoscope images.
      ​NOTE: In normal operation, the ACE indicator light on the image recorder and the LED on the capsule should blink synchronously.
   10. Disinfect the capsule endoscope with povidone-iodine and place it into the bladder.
   11. Close the bladder incision with a continuous 4-0 absorbable suture. Close the abdominal wall layers, then close the skin with a 2-0 silk suture. Transfer the Beagle dog to a cage after surgery. During the transfer, keep the image recorder within 1 m of the Beagle dog to avoid disconnection from the capsule endoscope.
4. Image acquisition
   1. Secure the image recorder to the top of the cage and ensure its safety.
   2. Click the Settings button on the workstation, then select Restart Image Recorder to reactivate the image recorder and confirm the capsule endoscope's operational status and connection.
   3. Confine Beagle A to a small dog cage for 8 h to maintain stillness. Allow Beagle B to move freely for 8 h.
   4. Have Beagle C maintain prone, supine, and squatting positions using gentle physical support and observe each position for 20 min, ensuring the animal's comfort and minimizing distress.
   5. Monitor and record bladder images from Beagle C using the image recorder. Click Real-time View to access the capsule's live video feed, then click the Start Recording button to initiate image acquisition and the Stop Recording button to terminate it. After sufficient data has been acquired, manually press the power button on the image recorder to turn it off.
   6. After approximately 8 h, when the ACT indicator light on the image recorders for Groups A and B has stopped flashing for 10 min, conclude the examination and turn off the recorders.
   7. At the end of the 8 h experimental period for Groups A and B, after image acquisition for Group C, anesthetize the dogs again following the procedures outlined in section 3.2.
   8. Surgically remove the capsule endoscope from the bladder through a cystotomy. Close the bladder and abdominal incisions as described in section 3.3.
      Allow the dogs to recover in clean, quiet cages with soft bedding. Administer anti-infective and fluid therapy as needed.
   9. Connect the image recorder to the workstation. Power on the image recorder and log in to the workstation software. Click Case Review; the system will then automatically download the image data. Save the image data to the workstation's hard drive once the download is complete.
   10. Analyze the acquired image data.

Results

In this study, each Beagle (n = 3) received one capsule endoscope surgically implanted into its bladder, and all animals demonstrated normal post-operative recovery. The capsule endoscopes functioned properly and remained safely within the dogs, as confirmed by imaging studies (Figure 2). Under remote control, the devices captured clear images of all anatomical regions of the bladder at various stages, including the dome, posterior wall, anterior wall, neck, and both the right and left side ...

Discussion

In recent years, with the advancement of endoscopic technology, both rigid and flexible cystoscopes have been widely applied in clinical practice. The conventional application of rigid cystoscopy is often cumbersome, with numerous blind spots and significant trauma. Patients experience high psychological stress during the procedure and may encounter discomfort or pain, as well as physiological responses such as increased heart rate, elevated blood pressure, and psychological stress reactions⁷. Fle...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
2-0 Silk suture	Ethicon Inc. (Beijing)	20193021851
20 G intravenous catheter	Shanghai Zhangdong Medical Technology Co., Ltd.	383012
4-0 absorbable suture	Ethicon Inc. (Beijing)	20193021851
8 mm endotracheal tube	Henan Yadu Industrial Co., Ltd.	Not applicable
Ampicillin	Chengdu Better Pharmaceutical Co., Ltd.	H19993625
Animal anesthesia machine	Nanjing Suprex Medical Equipment Co., Ltd.	Not applicable
Animal ECG monitor	Smiths Medical (US)	Not applicable
Animal laryngoscope	Shanghai Maiben Medical Technology Co., Ltd.	Not applicable
Beagle	School of Agriculture and Biology, Shanghai Jiao Tong University	Not applicable
Gauze Sponges	Gauze Sponges	13-761-52
Isoflurane	Abbott Laboratories (Shanghai)	H20059911
OMOM intelligent capsule endoscope	Chongqing Jinshan Science & Technology (Group) Co., Ltd.	NCG100
Povidone-iodine solution	Chengdu Yongan Pharmaceutical Co., Ltd.	H51022885
Propofol injection	Xi'an Libang Pharmaceutical Co., Ltd.	H19990281
Scalpel blade	Shanghai Pudong Golden Ring Medical Supplies Co., Ltd.	35Y1004
Sterile normal saline	Shijiazhuang No.4 Pharmaceutical Factory	H20066533
Surgical instruments	Johnson & Johnson Medical (Shanghai)	Not applicable
Dexmedetomidine hydrochloride	Jiangsu Hengrui Medicine Co., Ltd.	H20190407