X‐Ray Visualized Sensors for Peritoneal Dialysis Catheter Infection

Abstract

Peritonitis is a common complication for patients with end-stage renal disease undergoing peritoneal dialysis (PD) and is a direct cause or contributor in >15% deaths in PD patients. Since early detection is key to treatment, patients and their care teams need rapid, on-site diagnostics. A hydrogelbased peritoneal fluid pH sensor attached to a peritoneal dialysis catheter is developed to measure local acidosis indicative of peritoneal infections for early detection and monitoring of infections using X-ray imaging. The sensor comprises a polyacrylic acid hydrogel with embedded radiopaque markers enclosed in a polymer casing; contraction of the hydrogel in response to acidic pH is evident from the radiographically measured marker position. The sensor has a pH 4-8 response range; between pH 6.5 and 7.5 it responds linearly with a slope of 14% pH 7 length per pH unit, and about 1% length precision. The sensor is attached to a catheter and implanted in a rat peritoneum. Results in awake rats show a rapid pH drop during infection not observed in systemic C-reactive proteins (CRP) levels nor in the uninfected control animal, with negligible drift over 2 weeks. To our knowledge, this is the first report of an in vivo chemically responsive hydrogel sensor.

X‐Ray Visualized Synovial Fluid Carbon Dioxide Sensor for Early Detection of Prosthetic Hip Infections

“…The sensor was only tested in vitro and for future in vivo applications it will need to be tested in a live animal. We recently used an X-ray visualized pH sensor to measure peritoneal pH during infection in a 2-week rat peritoneal dialysis model, [49] and found negligible drift through the period and postmortem. This is consistent with previous studies, where we found the hydrogels to be robust even during long-term incubation in oxidative environments.…”

“…Previously, we developed hydrogel-based pH sensors to measure the pH of synovial fluid for early detection of hip infections and the pH of peritoneal fluid for peritoneal dialysis catheter infections using X-ray imaging. [48,49] Although no fouling effect on the sensor calibration curve, response rate or sensor degradation was observed in solutions of tryptic soy broth bacterial cell culture, bovine synovial fluid, bovine serum, highly oxidative hydrogen peroxide, and copper ion medium, or storage in pH 7 buffer, [50] biofouling maybe a potential concern for an indwelling sensor (especially over long periods (a hip prosthesis may last decades). We modified the pH sensor to determine CO 2 levels in synovial fluid with the added advantage of an improved lifetime by encasing the sensor and fluid in a CO 2 -permeable membrane which is impermeable to aqueous molecules.…”

A Magnetic Particle Imaging Approach for Minimally Invasive Imaging and Sensing With Implantable Bioelectronic Circuits

“…The sensor has a hyperintense signal in MR images that attenuates with increasing local temperature [25]. Besides MRI, X-ray compatible sensors have also been investigated in prior work on implantable x-ray-based blood pressure microsensor for coronary stent monitoring [26] and X-ray visualized sensors detecting infection within the peritoneal dialysis catheter [27].…”