Components of the Endogenous Cannabinoid System as Potential Biomarkers for Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic condition causing bladder pressure and pain. The condition is of unknown etiology and is often accompanied by other symptoms, including chronic pelvic pain, increased urinary urgency, and frequency. There is no definitive diagnosis for IC/BPS, and treatment options are currently limited to physical therapy and medications to help alleviate symptoms. The endogenous cannabinoid system (ECS) is an important regulator of numerous physiological systems, including the urinary system. Modulations of the ECS have been shown to be beneficial for IC/BPS-associated pain and inflammation in rodents. As an attempt to identify potential biomarkers for IC/BPS, we reviewed experimental studies where the components of the ECS have been quantified in experimental models of IC/BPS. Further investigations using well-defined animal models and patients’ data are required to obtain stronger evidence regarding the potential for ECS components to be definitive biomarkers for IC/BPS.

EXPRESS: High Bladder Pressure Reduces the Ability to Filter Out Interference From Distractors in Low Perceptual Load Condition

According to the load theory of attention, an active cognitive control mechanism is needed to ensure that behavior is controlled by target-relevant information when distractors are also perceived. Although the active cognitive control mechanism consists of working memory, cognitive flexibility, and inhibition components, predictions regarding the load effects of this mechanism were derived mostly from studies on working memory. We aimed to test whether these predictions are also valid for an inhibition component. The inhibitory load was manipulated physiologically by creating different bladder pressure and its effects on distractor interference were examined under low and high perceptual load conditions. Results indicated that the availability of inhibitory control resources was important for decreasing the interference of distractors in the low perceptual load condition and that the high perceptual load reduced the effects of distractors independently from the availability of inhibitory resources. Results were consistent with the predictions of load theory, and to the best of our knowledge, the study provided the first piece of evidence in terms of the load effect of inhibition component on distractor interference.

Comparison of Intra Abdominal Pressure Monitoring Techniques and the Effects of the Abdominal Compartment Syndrome

Background: Abdominal compartment syndrome (ACS) is a life-threatening condition that develops in the setting of increasing and uncontrolled intra-abdominal hypertension (IAH), leading to cardiovascular, respiratory, neurologic and/or renal dysfunction. Aims: To establish a porcine model for the evaluation of the effects of IAH on renal blood flow (RBF) and to determine if IVC pressure and/or Camino fiberoptic direct intraabdominal pressure measurements can accurately predict IAPs that have been derived using bladder pressure measurements. Methods: Abdominal laparotomy, placement of IAP and RBF measuring devices, and fascial closure were performed on six adult feeder pigs with a mean body weight of 25 +/- 5 kg. A Transonic Doppler flow probe, a suprapubic bladder catheter, a Camino fiberoptic probe, and a triple lumen central venous catheter were placed and then baseline measurements were taken of renal blood flow, bladder pressure, direct intra-peritoneal Camino pressure and IVC pressure, respectively. Normal saline was then infused into the abdomen to simulate increasing IAP. Following a 5–10-minute stabilization period, all measurements were again taken. Results: The correlation between IVC pressure and bladder pressure was 0.98, with a mean bias of -0.5 (SD 2.0; 95% CI: -0.9, -0.2). The correlation between direct IAP readings by Camino probe and bladder pressure was 0.91, with a mean bias of -3.9 (SD 4.3; 95% CI: -4.6, -3.2). There was a strong negative correlation (-0.95) between RBF and bladder pressure. At an IAP of 20 mmHg, RBF reduced by an average of 45.4% (95% CI: 40%, 50.8%). Upon abdominal decompression, RBF returned to 66.6% (95% CI: 54.3%, 78.9%) of its baseline value. Conclusions: A porcine model is effective in accurately measuring changes in real time RBF. RBF progressively declines as IAP increases, however upon decompression, it fails to achieve complete recovery. IVC pressure measurements correlate well with, and therefore may substitute, the gold standard bladder pressure measurements as representatives of IAP. Keywords: Abdominal Compartment syndrome, renal blood flow, intrabdominal hypertension, bladder pressure

Transurethral versus suprapubic catheterization to test urethral function in rats

Transurethral and suprapubic catheterization have both been used to test urethral function in rats; however, it is unknown whether these methods affect urethral function or if the order of catheterization affects the results. The aim of this cross-over designed experiment was to compare the effects of catheterization methods and order on leak point pressure (LPP) testing. LPP and simultaneous external urethral sphincter electromyography (EUS EMG) were recorded in anesthetized female virgin Sprague-Dawley rats in a cross-over design to test the effects of transurethral and suprapubic catheterization. There was no significant difference in peak bladder pressure during LPP testing whether measured with a transurethral or suprapubic catheter. There was no significant difference in peak bladder pressure between the first and second catheter insertions. However, peak EMG firing rate, as well as peak EMG amplitude and EMG amplitude difference between peak and baseline were significantly higher after the first catheter insertion compared to the second insertion, regardless of the catheter method. Our results suggest that route of catheterization does not alter urethral function, e.g. create a functional partial outlet obstruction. Either catheterization method could be used for LPP and/or EUS EMG testing in rats.

A Case and Brief Review of Bilious Ascites and Abdominal Compartment Syndrome from Pancreatitis-Induced Post-Roux-En-Y Gastric Remnant Leak

This is a case of a 55-year-old man with Roux-en-Y gastric bypass surgery 15 years prior who presented with acute pancreatitis and developed distributive shock, bacteremia, acute respiratory distress syndrome, anuric acute renal failure, and a distended abdomen with increasing ascitic fluid on imaging. An elevated bladder pressure, lactic acidosis, and anuria raised concern for abdominal compartment syndrome. Paracentesis was done and four liters of bilious ascitic fluid were drained. Intra-abdominal pressure was measured and improved from 27 cmH2O to 13 cmH2O with paracentesis. Mean arterial pressure and urine output also improved. The patient developed recurrent loculated intra-abdominal fluid collections, though ultrasound, CT scans with and without contrast, MRCP, ERCP, upper GI fluoroscopy, and small bowel enteroscopy failed to reveal a source of the bilious output. Ultimately, a gastrostomy tube was placed and delivery of contrast material through the tube revealed active extravasation from the remnant stomach. This case underscores the importance of considering post-surgical leak regardless of how remotely a Roux-en-Y surgery took place, confirms the importance of pursuing early gastrostomy tube placement and contrast administration when post-Roux-en-Y gastric remnant leaks are suspected, and demonstrates the role of paracentesis in critically ill patients with abdominal compartment syndrome.

Gastric and urinary bladder pressures correlate with intra-abdominal pressure in patients with morbid obesity

Intra-abdominal pressure (IAP) affects cardio-respiratory and hemodynamic parameters and can be measured directly or indirectly by measuring gastric or urinary bladder pressure. The aim of this study was to investigate the correlation between IAP, gastric pressure and urinary bladder pressure in patients with morbid obesity, at normal and elevated levels of IAP in two positions. As well, to examine the effects of increasing IAP and patient's position on hemodynamic and respiratory parameters. Twelve patients undergoing laparoscopic bariatric surgery were included. IAP, gastric pressure, and urinary bladder pressure were measured while patients were in the supine position and after 45° anti-Trendelenburg tilt. Mean inspiratory pressure, peak inspiratory pressure, and tidal volume were recorded and assessed. In supine position; directly measured IAP was 9.1 ± 1.8 mmHg, compared to 10 ± 3.6 and 8.9 ± 2.9 mmHg in the stomach and bladder, respectively. Increasing IAP to 15 mmHg resulted in an increased gastric pressure of 17 ± 3.8 mmHg, and urinary bladder pressure of 14.8 ± 3.9 mmHg. Gastric and urinary bladder pressures strongly correlated with IAP (R = 0.875 and 0.847, respectively). With 45° anti-Trendelenburg tilt; directly measured IAP was 9.4 ± 2.2 mmHg, and pressures of 10.8 ± 3.8 mmHg and 9.2 ± 3.8 mmHg were measured in the stomach and the bladder, respectively. Increasing IAP to 15 mmHg resulted in elevating gastric and bladder pressures to 16.6 ± 5.3 and 13.3 ± 4 mmHg, respectively. Gastric and urinary bladder pressures had good correlation with IAP (R = 0.843 and 0.819, respectively). Changing patient position from supine to 45° anti-Trendelenburg position resulted in decreased mean and peak inspiratory pressures, and increased tidal volume. Basal IAP is high in patients with morbid obesity. IAP shows positive correlation to gastric and urinary bladder pressures at both normal and elevated levels of IAP. Anti-Trendelenburg tilt of mechanically ventilated morbidly obese patients resulted in favorable effects on respiratory parameters.Trial Registration: The study was retrospectively registered in the NIH registry. Registration number is pending.

Visceral pressure stimulator for exploring hollow organ pain: a pilot study

Background The regulation and control of pressure stimuli is useful for many studies of pain and nociception especially those in the visceral pain field. In many in vivo experiments, distinct air and liquid stimuli at varying pressures are delivered to hollow organs such as the bladder, vagina, and colon. These stimuli are coupled with behavioral, molecular, or physiological read-outs of the response to the stimulus. Care must be taken to deliver precise timed stimuli during experimentation. For example, stimuli signals can be used online to precisely time-lock the stimulus with a physiological output. Such precision requires the development of specialized hardware to control the stimulus (e.g., air) while providing a precise read-out of pressure and stimulus signal markers. Methods In this study, we designed a timed pressure regulator [termed visceral pressure stimulator (VPS)] to control air flow, measure pressure (in mmHg), and send stimuli markers to online software. The device was built using a simple circuit and primarily off-the-shelf parts. A separate custom inline analog-to-digital pressure converter was used to validate the real pressure output of the VPS. Results Using commercial physiological software (Spike2, CED), we were able to measure mouse bladder pressure continuously during delivery of unique air stimulus trials in a mouse while simultaneously recording an electromyogram (EMG) of the overlying abdominal muscles. Conclusions This device will be useful for those who need to (1) deliver distinct pressure stimuli while (2) measuring the pressure in real-time and (3) monitoring stimulus on–off using physiological software.