Establishing a biomarker for postoperative ileus in humans - Results of the BiPOI trial

Safety and Suitability of the SmartPill® after Abdominal Surgery: Results of the Prospective, Two-Armed, Open-Label PIDuSA Trial

INTRODUCTION

Postoperative ileus (POI) is a common complication after abdominal surgery. Until today, an evidence-based treatment of prolonged POI is still lacking, which can be attributed to the poor quality of clinical trials. Various different surrogate markers used to define POI severity are considered to be the cause of low-quality trials making it impossible to derive treatment recommendation. The SmartPill®, which is able to record pH values, temperature and pressure after ingestion, could be an ideal tool to measure transit times and peristalsis and therefore analyze POI severity. Unfortunately, the device has no approval for postoperative use due to safety concerns. The primary objective of the study is to determine safety of the SmartPill® in patients undergoing surgery. Secondary objectives were the quality of the recorded data and the suitability of the SmartPill® for analyzing intestinal motility after different surgical procedures.

METHODS

The PIDuSA Study is a prospective, 2-arm, open-label trial. At the end of surgery, the SmartPill® was applied to 49 patients undergoing abdominal surgery having a high risk for impaired intestinal motility and 15 patients undergoing extra-abdominal surgery. Patients were visited daily to access safety data of the SmartPill® on the basis of adverse and serious adverse events (AEs/SAEs). Suitability and data quality were investigated by analyzing data completeness and feasibility to determine transit times and peristalsis for all sections of the gastrointestinal tract.

RESULTS

In total, 179 AEs and 8 SAEs were recorded throughout the study affecting 42 patients in the abdominal (158 AEs) and 9 patients in the extra-abdominal surgery group (21 AEs, p = 0.061); none of them were device related. Primary capsule failure was observed in 5 patients, ultimately resulting in an impossibility of data analysis in only 3 patients (4.4%). 9% of the recorded data were incomplete due to the patient's incompliance in keeping the receiver close to the body. In 3 patients (4.4%), isolated small bowel transit could not be determined due to pH alterations as a result of prolonged POI.

DISCUSSION

Our study demonstrates that the use of the SmartPill® is safe after surgery but requires a reasonable patient compliance to deliver meaningful data. An objective analysis of transit times and peristalsis was possible irrespective of type and site of surgery in over 95% indicating that the SmartPill® has the potential to deliver objective parameters for POI severity in future clinical trials. However, in some patients with prolonged POI, analysis of small bowel transit could be challenging.

State-of-the-art colorectal disease: postoperative ileus

PURPOSE

Postoperative Ileus (POI) remains an important complication for patients after abdominal surgery with an incidence of 10-27% representing an everyday issue for abdominal surgeons. It accounts for patients' discomfort, increased morbidity, prolonged hospital stays, and a high economic burden. This review outlines the current understanding of POI pathophysiology and focuses on preventive treatments that have proven to be effective or at least show promising effects.

METHODS

Pathophysiology and recommendations for POI treatment are summarized on the basis of a selective literature review.

RESULTS

While a lot of therapies have been researched over the past decades, many of them failed to prove successful in meta-analyses. To date, there is no evidence-based treatment once POI has manifested. In the era of enhanced recovery after surgery or fast track regimes, a few approaches show a beneficial effect in preventing POI: multimodal, opioid-sparing analgesia with placement of epidural catheters or transverse abdominis plane block; μ-opioid-receptor antagonists; and goal-directed fluid therapy and in general the use of minimally invasive surgery.

CONCLUSION

The results of different studies are often contradictory, as a concise definition of POI and reliable surrogate endpoints are still absent. These will be needed to advance POI research and provide clinicians with consistent data to improve the treatment strategies.

The clinical and economical impact of postoperative ileus in patients undergoing colorectal surgery

BACKGROUND

Colorectal surgery is associated with postoperative ileus (POI). Despite its widespread manifestation, the influence of POI on recovery, quality of life (QoL), and costs is largely unknown. The aim of this study was to assess whether the inflammatory processes found in experimental studies are also evident in patients undergoing colorectal surgery. In addition, the impact of POI on short and long-term QoL and costs was investigated.

METHODS

We analyzed the outcomes of the SANICS-II trial, including prospective evaluation of inflammatory parameters in blood samples, costs from a societal perspective and QoL, using validated questionnaires. Outcomes were compared between patients with and without POI, and in particular patients with POI as unique complication.

KEY RESULTS

A total of 265 patients (POI, n = 66 vs non-POI, n = 199) were included and 38/66 had POI as only complication. CRP levels were significantly increased on postoperative day (POD) 1, 2, 3, and 4 in patients with POI. Furthermore, plasma levels of cytokines IL-6, Il-8 and IL-10 were significantly increased the first 2 days after resection. Patients with POI had a higher overall complication rate and a reduced QoL 3 months postoperatively, even in the only POI group. Moreover, mean societal cost per patient with POI was 38%-47% higher at 3 months postoperatively.

CONCLUSIONS & INFERENCES

Supporting findings from experimental studies, inflammatory parameters were increased in patients with only POI and comparable with all patients with POI. These results demonstrate the impact and large contribution of POI in postoperative inflammation, costs and QoL in patients undergoing colorectal surgery.

Leukocyte-Derived Interleukin-10 Aggravates Postoperative Ileus

Objective: Postoperative ileus (POI) is an inflammation-mediated complication of abdominal surgery, characterized by intestinal dysmotility and leukocyte infiltration into the muscularis externa (ME). Previous studies indicated that interleukin (IL)-10 is crucial for the resolution of a variety of inflammation-driven diseases. Herein, we investigated how IL-10 affects the postoperative ME inflammation and found an unforeseen role of IL-10 in POI. Design: POI was induced by a standardized intestinal manipulation (IM) in C57BL/6 and multiple transgenic mouse strain including C-C motif chemokine receptor 2^-/-, IL-10^-/-, and LysM^cre/IL-10^fl/fl mice. Leukocyte infiltration, gene and protein expression of cytokines, chemokines, and macrophage differentiation markers as well as intestinal motility were analyzed. IL-10 serum levels in surgical patients were determined by ELISA. Results: IL-10 serum levels were increased in patient after abdominal surgery. In mice, a complete or leucocyte-restricted IL-10 deficiency ameliorated POI and reduced the postoperative ME neutrophil infiltration. Infiltrating monocytes were identified as main IL-10 producers and undergo IL-10-dependent M2 polarization. Interestingly, M2 polarization is not crucial to POI development as abrogation of monocyte infiltration did not prevent POI due to a compensation of the IL-10 loss by resident macrophages and neutrophils. Organ culture studies demonstrated that IL-10 deficiency impeded neutrophil migration toward the surgically traumatized ME. This mechanism is mediated by reduction of neutrophil attracting chemokines. Conclusion: Monocyte-derived macrophages are the major IL-10 source during POI. An IL-10 deficiency decreases the postoperative expression of neutrophil-recruiting chemokines, consequently reduces the neutrophil extravasation into the postsurgical bowel wall, and finally protects mice from POI.