Fig. 7.1
Diagram showing abdominal site marking done before the procedure. The location of the catheter curl in relation to the symphysis pubis is an important determination as catheters that extend too deep in the pelvis may result in infusion or drain pain during PD exchanges. When marking the entry site (small arrow) and exit site (large arrow), it is essential to align the upper border of the PD catheter curl with the upper border of the symphysis pubis (curved arrow)
Catheter Selection
A variety of body configurations of patients has resulted in modification of the standard Tenckhoff catheter in terms of the length and presence of a pre-formed bend (swan neck) in the subcutaneous section of the catheter to assist in creation of a downward facing exit site and avoidance of the beltline. The chosen catheter design would allow for pelvic location of the distal catheter (keeping it out of reach of omentum) and appropriate exit location that is easily accessible for the patients and away from belt line or skin crease/folds. Three standard variations of the Tenckhoff catheters are: straight intercuff segment, pre-formed bend between cuffs (Swan neck design) and a modular (two-piece) extended system to produce upper abdominal or chest exit-site locations. The literature is not consistent regarding superiority of either configuration (straight versus Swan neck configuration).
The authors’ preferred catheter is the Swan neck (pre-curved), double-cuff, curled catheter (Fig. 7.2). The authors feel that the swan neck design aids in orienting the catheter caudally into the pelvis. The curled distal portion of the catheter adds additional mass to encourage the distal catheter to remain low in the pelvis and therefore helps prevent cephalad migration of the distal end of the catheter. The curled tubing and numerous inflow/outflow holes diffuse the dialysate gently into and out of the patient. The two catheter cuffs are anchored preperitoneal and subcutaneously. The pre-peritoneal cuff (deep cuff) is anchored within the anterior rectus sheath to reduce the possibility of dialysate leakage from the peritoneal cavity. The subcutaneous cuff (superficial cuff) is placed deep subcutaneously about 2–4 cm from the catheter exit site, to avoid cuff infection or extrusion. Both cuffs anchor the catheter via tissue in-growth and serve as a barrier to infection. The catheter is prepared by placing the catheter in a surgical bowl filled with saline and manually compressing the Dacron cuffs to extrude any air within the cuffs that may inhibit tissue in-growth.
Fig. 7.2
Photograph showing a swan neck (pre-curved), double-cuff, curled catheter
Catheter Placement Procedure
Intra-procedure Preparation and Monitoring
The patient is placed supine on the angiographic table in the procedure room. Preliminary ultrasound of the abdomen is performed to help determine the safest puncture site (entry site) and plan for the subcutaneous tunnel and the catheter exit site. The puncture site is defined as the site of the initial needle stick but, due to caudal angling of the needle, the entry site into the peritoneum is 2–3 cm inferior. The subcutaneous tunnel is defined as the tunnel through which the catheter will be passed under the skin. The exit site is defined as the site on the skin where the catheter will exit from the subcutaneous tunnel. The safest puncture site should be determined by gray-scale ultrasound, color-Doppler ultrasound and fluoroscopy. Gray-scale ultrasound will determine the site on the anterior abdominal wall that does not have bowel loops underneath, or has the maximum separation between the anterior abdominal wall and the bowel loops, to minimize the risk of inadvertent bowel puncture. On gray-scale ultrasound, the subcutaneous tissue is visualized as a superficial hypoechoic band and the rectus abdominis muscle is visualized as a deeper hypoechoic band with linear high specular echoes. The parietal peritoneum is visualized as a thin echogenic linear streak just posterior to the rectus abdominis muscle. The air-filled bowel loops demonstrate ring-down artifact caused by air (Fig. 7.3), while the fluid-filled bowel loops will appear hypoechoic. Both air and fluid-filled bowel loops might demonstrate motion on real time ultrasound confirming their nature. Color Doppler or Power Doppler ultrasound can then be used to confirm the absence of any large arteries, mainly the inferior epigastric artery and its branches, coursing through or deep to the anterior abdominal wall (Fig. 7.4). If these are present, then a search for a different puncture site should be attempted to avoid transecting these arteries which can result in abdominal wall or intra-abdominal hematoma. A site in the mid-rectus abdominis muscle is preferred for placement of the catheter compared to the thinner lateral or medial aspects of the rectus abdominis muscle since one of the cuffs of the catheter will be implanted in the muscle. In the authors’ experience, scanning for a safe puncture site that is 2–4 cm lateral and superior to the umbilicus is usually optimal. The subcutaneous tunnel usually makes a gentle lateral and inferior course towards the exit site which is located lateral and inferior to the initial puncture site. All planned sites should be marked with a pen.
Fig. 7.3
Gray scale ultrasound image showing the different layers of the anterior abdominal wall. The subcutaneous fat appears as a superficial hypoechoic band (large arrow). The rectus abdominis muscle appears as a deeper hypoechoic structure with linear high specular echoes (small arrow). The peritoneum appears as a thin linear hyperechoic streak deep to the rectus abdominis muscle (arrowhead). The air-filled bowel loops demonstrate ring-down artifact caused by air (curved arrow)
Fig. 7.4
Color Doppler ultrasound image shows the inferior epigastric artery (small arrow) coursing through the rectus abdominis muscle (large arrow)
The hair on the anterior abdominal wall in the involved area is then shaved. The abdomen is then prepped with an antiseptic scrub and then sterilely draped to provide exposure to the initial puncture site and the expected exit site. Mild or moderate sedation is performed using intravenous midazolam hydrochloride and fentanyl citrate. Vital sign parameters (pulse, blood pressure, oxygen saturation) and bedside electrocardiogram are continuously monitored during the procedure by the operating physician and a dedicated nurse. Anesthesiology assistance is not routinely required but may be considered in the case of patients requiring CPAP ventilation or on chronic narcotics. If on CPAP, those patients should bring their own home devices to the procedure.
Ultrasound Guidance
As mentioned, ultrasound guidance should be used in all cases for the initial puncture to ensure safe entry into the peritoneal cavity. The use of gray-scale and Doppler ultrasound allows for visualization and avoidance of bowel and vascular structures such as the inferior epigastric artery. The safest initial puncture site is again confirmed using ultrasound. Local anesthesia using 1% lidocaine is infiltrated within the skin, subcutaneous, and deep tissues of the anterior abdominal wall at the anticipated puncture site.
A 21 gauge micropuncture needle is usually used. Alternatively, a blunt tip needle such as an 18 gauge Hawkins-Adkins needle or a Veress needle can be used. Using ultrasound guidance, the needle is advanced in a caudal direction towards the pelvis at a 45° angle from the skin surface and slightly laterally (Fig. 7.5). Taking a caudal and lateral tract through the rectus sheath, helps direct the catheter in the caudal direction which has been associated with less cephalic catheter migration in the surgical literature [14, 15]. The parietal peritoneal layer is well-innervated and the patient usually experiences transient discomfort as the needle traverses the parietal peritoneum. A 22 gauge, 15 cm Chiba needle can be used in the obese patient and the curved low frequency probe can be used to assess for the needle passing into the peritoneal cavity, if the linear probe cannot provide visualization.
Fig. 7.5
(a) Photograph showing a 21 gauge micropuncture needle advanced in a caudal direction towards the pelvis at a 45° angle from the skin surface using ultrasound guidance. (b) Ultrasound image showing needle puncture of the peritoneum using ultrasound guidance
Fluoroscopic Guidance
Following the ultrasound-guided entry into the peritoneal cavity, approximately 3–5 mL of non-ionic contrast material can be injected and visualized under fluoroscopy. The free spread of contrast material around the bowel loops confirms successful entry into the peritoneal cavity (Fig. 7.6). Contrast outlining the mucosal folds of the small bowel or the colonic haustra indicates inadvertent puncture of bowel. If bowel perforation occurs, the procedure is terminated in order to avoid catheter infection and peritonitis. The patient can be managed conservatively or treated with oral Ciprofloxacin 500 mg twice daily for 2 weeks after which the patient can return for a second attempt.
Fig. 7.6
Fluoroscopic image after injection of 5 ml of non-ionic contrast material into the peritoneal cavity showing free spread of contrast material outlining the outer surface of the bowel loops and confirming successful entry into the peritoneal cavity
After visual confirmation of successful entry into the peritoneal cavity, a 0.018 in. nitinol wire that accompanies the original micro-introducer kit is threaded into the peritoneal cavity (Fig. 7.7). The nitinol wire is left in place and the 21 gauge needle is then exchanged over the nitinol wire for the 4 or 5 French microsheath included in the microintroducer kit (Fig. 7.8). The wire and inner stiffener of the sheath are then removed and contrast may again be injected through the sheath to confirm that the sheath is in the peritoneal cavity. A 0.035 in. guide wire, preferably a stiff glide wire, is advanced through the sheath and directed toward the pelvis under fluoroscopic guidance. During advancement, the wire is negotiated through the path of least resistance around bowel and omentum to reach the pelvis. Alternately, when a larger bore needle (Veress-type) is used for entry, a 0.035 in. guide wire can be directly introduced through the needle. The 0.035 in. wire is ideal as it allows for manipulation around the bowel and is stiff enough to allow catheter traction during the final catheter placement. If advancement of the wire down to the pelvic cavity is difficult or problematic due to adhesions from prior surgery, a 4 or 5 French angled-tip catheter together with the guide wire can be used to negotiate down into the pelvic cavity. The 4-French microsheath is then exchanged over the wire for a 6-French introducer sheath with a sidearm (Fig. 7.9). Contrast may again be injected through the sidearm of the introducer sheath to confirm location of the sheath in the peritoneal cavity. A 2–4 cm incision is made at the site of entry of the introducer sheath followed by blunt dissection down to the rectus abdominis muscle using a finger or curved hemostat (Fig. 7.10). Three hundred to 1000 mL of normal saline may be infused through the sidearm of the introducer sheath to separate the bowel loops and facilitate the passage of the catheter into the peritoneum.
Fig. 7.7
Photograph showing a 0.018 in. nitinol wire threaded through the introducer needle into the peritoneal cavity
Fig. 7.8
Photograph showing a 4-French microsheath introduced over the 0.018 nitinol wire
Fig. 7.9
Photograph showing the placement of a 6-French introducer sheath over the stiff glide wire
Fig. 7.10
Photograph showing a 2 cm incision made at the site of entry of the introducer sheath followed by blunt dissection with a finger down to the rectus abdominis muscle
The sheath is then removed and the tract is serially dilated over the wire with an 8-French, then 12-French, then 14-French dilator (Fig. 7.11). Dilatation should be done under fluoroscopic visualization and the dilators should be directed caudally towards the pelvic cavity in the same direction as the original needle stick in order to avoid the wire and the dilator being pushed in the subcutaneous tissue superficial to the rectus abdominis muscle, rather than through the muscle into the peritoneal cavity. A 16-French, 15 cm peel-apart sheath, that is typically included in the peritoneal catheter kit, is advanced into the peritoneal cavity over the wire in the deep pelvic direction (Fig. 7.12).
