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NERv was co-founded by two University of Waterloo Engineering graduates who were determined to see that no patient loses their life because of an undetected post-operative complication. Our growing team of engineers and surgeons is committed to achieving that goal by developing sensors and predictive models to detect complications at their onset. Post-operative recovery can be a stressful period and we aim to improve outcomes.

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Window to the Abdomen: Addressing the Gaps between Patient Monitoring and Diagnostic Medicine through Cutting Edge Sensor Platforms

Written By

Nour Helwa, Manaswi Sharma

Despite enhancements in surgical techniques and patient care procedures, 1-30% of patients will be affected by anastomotic leaks following general surgery. (Hirst, Tiernan, Millner & Jayne, 2014) These refer to leakage of gastrointestinal (GI) contents into the abdominal cavity from the site of the surgical procedure, causing severe consequences like infections, septic shock, and even death. (Platell et al., 2007) Anastomotic leaks are the Achilles’ heel of general surgery, potentially increasing patient morbidity from 28.4% to 98%. (Turrentine et al., 2015) They also cause a direct rise in healthcare costs by increasing the duration of hospital stays from an average of 5 to 13 days. (Turrentine et al., 2015) Timely diagnosis and prompt therapeutic action can significantly reduce the negative consequences of anastomotic leaks and the need for re-operation. However, currently, there is no diagnostic system capable of detecting leaks at the time of onset. (Hirst et al., 2014) As a result, most anastomotic leaks are diagnosed 2-3 days after the onset, which can often exacerbate the consequences, reducing the overall survival of affected patients. (Hirst et al., 2014)

According to the current standard of care, physicians often place surgical drains close to the site of anastomosis that drain excess fluid from the abdominal cavity after the surgery. The properties of the drained fluid such as volume, colour, viscosity, and odour provide clues regarding the presence of some complications such as infections. (Hirst et al., 2014) For treatment to begin, the diagnoses must be confirmed using CT scans or laboratory tests. Unfortunately, laboratory and imaging tests require specialized facilities, equipment, and personnel, thereby making them susceptible to delays, especially if there is an intervening weekend. (Hirst et al., 2014) They provide information from the body for a point in time, however, the state of the complication and the body constantly evolves. Hence, the tests must be repeated regularly, which drives up associated healthcare costs. (Straatman, Cuesta, de Lange-de Klerk & van der Peet, 2015) An international study of 399 patients reported a 3.4-fold increase in patient cost due to complications after major abdominal surgeries. (Straatman et al., 2015) The diagnostic methods also have a significant rate of false-negative outcomes, causing further delays in treatment, and exacerbating the consequences of a developing complication. (Hirst et al., 2014) Due to these shortcomings in the current methods of diagnosis, there is a gap in patient care that must be addressed to facilitate timely detection and treatment of postoperative complications.

Researchers have studied changes in levels of various biomarkers after surgery that could facilitate time-sensitive diagnosis of postoperative complications. These include lactate, serum C-reacting protein (CRP), cytokines, pH and other markers of inflammation. (Hirst et al., 2014) Of the studied biomarkers, pH has received the most support in the academic community for characterizing the internal state of the abdominal cavity. A hallmark feature of anastomotic leaks and several other postoperative complications is inflammation, which is caused by the enhanced activity of our immune cells at the site of the complication. (Yang et al., 2013) While the pH of different regions of the gastrointestinal tract is highly regulated, inflammation causes a clinically significant drop in this value, making it a valuable predictor of developing complications. Deviations from the normal range of pH can therefore indicate oncoming complications before any clinical symptoms begin appearing. (Yang et al., 2013) A study conducted in 753 patients by Dr. Yang et al. showed that pH was able to detect postoperative complications with a sensitivity of 98.7% and a specificity of 94.7%. (Yang et al., 2013) Similarly, some researchers have studied the use of electrical conductivity as a biomarker for detecting postoperative complications. Through animal studies in rats, it was shown that spillage of contents of the gut into the peritoneal cavity increases the electrical conductivity of the peritoneal fluid. (DeArmond, Cline & Johnson, 2010) In summary, pH and electrical conductivity have shown great promise as biomarkers for predicting oncoming complications following abdominal surgery.

The research studies mentioned above had also utilized laboratory settings for assessing biomarkers and conducting tests. While their results are crucial to understanding the utility of different biomarkers, the hurdles presented by current diagnostic tests persist. This is reflected in a review of the literature, that summarizes what the diagnostic space is lacking: a bedside diagnostic test capable of monitoring the patient status continuously. (Hirst et al., 2014) To bridge the gap between patient monitoring and diagnostic tests, NERv has created a solution that complements the existing standard of care by converting surgical drains into smart monitoring tools.

NERv solution includes a small device that attaches between commonly used peritoneal drains, such that excess fluid leaving the body passes through the device. While the fluid passes through the device channel, it interacts with NERv’s micro-sensor platform technology, which measures and records the physiological profile of the drainage fluid, including pH and electrical conductivity. The real-time data is relayed to an accompanying tablet, where all measurements are displayed as trends for easy interpretation via NERv’s Mobile Application. The device, therefore, provides a window to the abdomen, providing round-the-clock bedside monitoring of patients, in a safe and minimally invasive manner.

Continuous measurements of peritoneal drainage fluid characteristics can facilitate early diagnosis by prompting healthcare providers when deviations from normal ranges are observed. Early diagnosis of various complications can enhance patient recovery, overall survival, disease-free survival, and overall quality of life, while simultaneously reducing healthcare costs and hospital stay durations (Hirst et al., 2014). It would also allow for smoother patient flow through the hospitals, reducing liability on physicians, as well as reducing the healthcare utilization burden on institutions. With a dedicated team, complete with the support of several revered healthcare providers and experts in the field, NERv aims to eliminate the delay caused by current diagnostic techniques. It is expected that with the device in the physicians’ arsenal, it has the potential to create a global impact and transform the landscape of diagnostic medicine.


DeArmond, D., Cline, A., & Johnson, S. (2010). Anastomotic Leak Detection by Electrolyte Electrical Resistance. Journal Of Investigative Surgery, 23(4), 197-203. doi: 10.3109/08941930903469458

Hirst, N., Tiernan, J., Millner, P., & Jayne, D. (2014). Systematic review of methods to predict and detect anastomotic leakage in colorectal surgery. Colorectal Disease, 16(2), 95-109. doi: 10.1111/codi.12411

Platell, C., Barwood, N., Dorfmann, G., & Makin, G. (2007). The incidence of anastomotic leaks in patients undergoing colorectal surgery. Colorectal Disease, 9(1), 71-79. doi: 10.1111/j.1463-1318.2006.01002.x

Straatman, J., Cuesta, M., de Lange-de Klerk, E., & van der Peet, D. (2015). Hospital Cost-Analysis of Complications after Major Abdominal Surgery. Digestive Surgery, 32(2), 150-156. doi: 10.1159/000371861

Turrentine, F., Denlinger, C., Simpson, V., Garwood, R., Guerlain, S., & Agrawal, A. et al. (2015). Morbidity, Mortality, Cost, and Survival Estimates of Gastrointestinal Anastomotic Leaks. Journal Of The American College Of Surgeons, 220(2), 195-206. doi: 10.1016/j.jamcollsurg.2014.11.002

Yang, L., Huang, X., Xu, L., Zhou, X., Zhou, J., & Yu, D. et al. (2013). Acidic Pelvic Drainage as a Predictive Factor For Anastomotic Leakage after Surgery for Patients with Rectal Cancer. Asian Pacific Journal Of Cancer Prevention, 14(9), 5441-5447. doi: 10.7314/apjcp.2013.14.9.5441