Continuous Intra-abdominal Pressure Research Articles

Validation of continuous intraabdominal pressure measurement: feasibility and accuracy assessment using a capsular device in in-vivo studies

BackgroundMonitoring Intraabdominal Pressure (IAP) is essential in critical care, as elevated IAP can lead to severe complications, including Abdominal Compartment Syndrome (ACS). Advances in technology, such as digital capsules, have opened new avenues for measuring IAP non-invasively. This study assesses the feasibility and effectiveness of using a capsular device for IAP measurement in an animal model.MethodIn our controlled experiment, we anesthetized pigs and simulated elevated IAP conditions by infusing CO2 into the peritoneal cavity. We compared IAP measurements obtained from three different methods: an intravesical catheter (IAPivp), a capsular device (IAPdot), and a direct peritoneal catheter (IAPdir). The data from these methods were analyzed to evaluate agreement and accuracy.ResultsThe capsular sensor (IAPdot) provided continuous and accurate detection of IAP over 144 h, with a total of 53,065,487 measurement triplets recorded. The correlation coefficient (R²) between IAPdot and IAPdir was excellent at 0.9241, demonstrating high agreement. Similarly, IAPivp and IAPdir showed strong correlation with an R² of 0.9168.ConclusionThe use of capsular sensors for continuous and accurate assessment of IAP marks a significant advancement in the field of critical care monitoring. The high correlation between measurements from different locations and methods underscores the potential of capsular devices to transform clinical practices by providing reliable, non-invasive IAP monitoring.

Evaluation of the TraumaGuard Balloon-in-Balloon Catheter Design for Intra-Abdominal Pressure Monitoring: Insights from Pig and Human Cadaver Studies.

Introduction: Intra-abdominal pressure (IAP) monitoring is crucial for the detection and prevention of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS). In the 1970s, air-filled catheters (AFCs) for urodynamic studies were introduced as a solution to overcome the limitations of water-perfused catheters. Recent studies have shown that for correct IAP measurement with traditional AFC, the bladder needs to be primed with 25 mL of saline solution to allow pressure wave transmission to the transducer outside of the body, which limits continuous IAP monitoring. Methods: In this study, a novel triple balloon, air-filled TraumaGuard (TG) catheter system from Sentinel Medical Technologies (Jacksonville, FL, USA) with a unique balloon-in-balloon design was evaluated in a porcine and cadaver model of IAH via laparoscopy (IAPgold). Results: In total, 27 and 86 paired IAP measurements were performed in two pigs and one human cadaver, respectively. The mean IAPTG was 20.7 ± 10.7 mmHg compared to IAPgold of 20.3 ± 10.3 mmHg in the porcine study. In the cadaver investigation, the mean IAPTG was 15.6 ± 10.8 mmHg compared to IAPgold of 14.4 ± 10.4 mmHg. The correlation, concordance, bias, precision, limits of agreement, and percentage error were all in accordance with the WSACS (Abdominal Compartment Society) recommendations and guidelines for research. Conclusions: These findings support the use of the TG catheter for continuous IAP monitoring, providing early detection of elevated IAP, thus enabling the potential for prevention of IAH and ACS. Confirmation studies with the TraumaGuard system in critically ill patients are warranted to further validate these findings.

In Vitro Validation of a Novel Continuous Intra-Abdominal Pressure Measurement System (TraumaGuard).

Introduction: Intra-abdominal pressure (IAP) has been recognized as an important vital sign in critically ill patients. Due to the high prevalence and incidence of intra-abdominal hypertension in surgical (trauma, burns, cardiac) and medical (sepsis, liver cirrhosis, acute kidney injury) patients, continuous IAP (CIAP) monitoring has been proposed. This research was aimed at validating a new CIAP monitoring device, the TraumaGuard from Sentinel Medical Technologies, against the gold standard (height of a water column) in an in vitro setting and performing a comparative analysis among different CIAP measurement technologies (including two intra-gastric and two intra-bladder measurement devices). A technical and clinical guideline addressing the strengths and weaknesses of each device is provided as well. Methods: Five different CIAP measurement devices (two intra-gastric and three intra-vesical), including the former CiMON, Spiegelberg, Serenno, TraumaGuard, and Accuryn, were validated against the gold standard water column pressure in a bench-top abdominal phantom. The impacts of body temperature and bladder fill volume (for the intra-vesical methods) were evaluated for each system. Subsequently, 48 h of continuous monitoring (n = 2880) on top of intermittent IAP (n = 300) readings were captured for each device. Using Pearson's and Lin's correlations, concordance, and Bland and Altman analyses, the accuracy, precision, percentage error, correlation and concordance coefficients, bias, and limits of agreement were calculated for all the different devices. We also performed error grid analysis on the CIAP measurements to provide an overview of the involved risk level due to wrong IAP measurements and calculated the area under the curve and time above a certain IAP threshold. Lastly, the robustness of each system in tracking the dynamic variations of the raw IAP signal due to respirations and heartbeats was evaluated as well. Results: The TraumaGuard was the only technology able to measure the IAP with an empty artificial bladder. No important temperature dependency was observed for the investigated devices except for the Spiegelberg, which displayed higher IAP values when the temperature was increased, but this could be adjusted through recalibration. All the studied devices showed excellent ability for IAP monitoring, although the intra-vesical IAP measurements seem more reliable. In general, the TraumaGuard, Accuryn, and Serenno showed better accuracy compared to intra-gastric measurement devices. On average, biases of +0.71, +0.93, +0.29, +0.25, and -0.06 mm Hg were observed for the CiMON, Spiegelberg, Serenno, TraumaGuard, and Accuryn, respectively. All of the equipment showed percentage errors smaller than 25%. Regarding the correlation and concordance coefficients, the Serenno and TraumaGuard showed the best results (R2 = 0.98, p = 0.001, concordance coefficient of 99.5%). Error grid analysis based on the Abdominal Compartment Society guidelines showed a very low associated risk level of inappropriate treatment strategies due to erroneous IAP measurements. Regarding the dynamic tracings of the raw IAP signal, all the systems can track respiratory variations and derived parameters; however, the CiMON was slightly superior compared to the other technologies. Conclusions: According to the research guidelines of the Abdominal Compartment Society (WSACS), this in vitro study shows that the TraumaGuard can be used interchangeably with the gold standard for measuring continuous IAP, even in an empty artificial bladder. Confirmation studies with the TraumaGuard in animals and humans are warranted to further validate these findings.

Feasibility of continuous intra-uterine pressure measurements during amnioreduction in twin-to-twin transfusion syndrome therapy

IntroductionThis work explores the feasibility of simultaneous and continuous intra-abdominal, intra-uterine, and arterial blood pressure measurements to examine the hemodynamic perturbation expected during therapeutic amnioreduction and to better understand the protective role of the placenta during that treatment. MethodsPatients with twin-to-twin transfusion syndrome were treated with fetoscopic laser ablation followed by amnioreduction. Intra-abdominal, intra-uterine, and mean arterial pressures were simultaneously recorded during amnioreduction performed in steps of 200 mL. Placental thickness and uterine dimensions were measured before and after amnioreduction by ultrasonography. ResultsUseful pressure recordings were obtained between volume reduction steps and short hands-off periods in four studies. Median amnioreduction volume was 1400 mL corresponding to a median uterine volume reduction of 1121 mL. Mean intra-uterine pressure significantly fell from 24.8 to 13.6 mmHg (p = 0.011) and intra-abdominal pressure significantly decreased from 13.4 to 9.2 mmHg after amnioreduction (p = 0.015). Uterine pressure recordings revealed transient contractions (A, in mmHg) following individual amnioreduction steps, which increased with fractional amnioreduction (F, no dimension) (A = 17.23*F + 11.81; r = 0.50, p = 0.001). DiscussionSimultaneous and continuous measurement of intra-abdominal, intra-uterine, and arterial blood pressures during amnioreduction is feasible. The dynamics reveal transient uterine contractions reaching levels comparable to those seen during childbirth which seem to oppose impending maternal hypovolemia by placental steal at the expense of temporarily reducing placental perfusion pressure and underline the importance of uterine and placental interaction.

Assessment of Intra-Abdominal Pressure with a Novel Continuous Bladder Pressure Monitor—A Clinical Validation Study

Intra-abdominal hypertension and the resulting abdominal compartment syndrome are serious complications of severely ill patients. Diagnosis requires an intra-abdominal pressure (IAP) measurement, which is currently cumbersome and underused. We aimed to test the accuracy of a novel continuous IAP monitor. Adults having laparoscopic surgery and requiring urinary catheter intra-operatively were recruited to this single-arm validation study. IAP measurements using the novel monitor and a gold-standard foley manometer were compared. After anesthesia induction, a pneumoperitoneum was induced through a laparoscopic insufflator, and five randomly pre-defined pressures (between 5 and 25 mmHg) were achieved and simultaneously measured via both methods in each participant. Measurements were compared using Bland-Altman analysis. In total, 29 participants completed the study and provided 144 distinct pairs of pressure measurements that were analyzed. A positive correlation between the two methods was found (R2 = 0.93). There was good agreement between the methods, with a mean bias (95% CI) of -0.4 (-0.6, -0.1) mmHg and a standard deviation of 1.3 mmHg, which was statistically significant but of no clinical importance. The limits of agreement (where 95% of the differences are expected to fall) were -2.9 and 2.2 mmHg. The proportional error was statistically insignificant (p = 0.85), suggesting a constant agreement between the methods across the range of values tested. The percentage error was 10.7%. Continuous IAP measurements using the novel monitor performed well in the clinical setup of controlled intra-abdominal hypertension across the evaluated range of pressures. Further studies should expand the range to more pathological values.

Pre-Clinical Validation of A Novel Continuous Intra-Abdominal Pressure Measurement Equipment (SERENNO).

Introduction: Increased intra-abdominal pressure (IAP) has an important impact on morbidity and mortality in critically ill patients. The SERENNO Sentinel system (Serenno Medical, Yokne’am Illit, Israel) is a novel device that allows automatic and continuous IAP measurements. Aims: Pre-clinical validation in a bench model study comparing the new device with the gold standard method and two other continuous IAP measurement devices. Methods: IAP measurement with the novel SERENNO device (IAPSER) was compared with the gold standard IAPH2O (water column height) and two other automatic and continuous IAP measurement devices: IAPCiM measured via the CiMON device (Pulsion Medical Systems, Munich, Germany) and IAPSPIE measured using the Spiegelberg device (Spiegelberg, Hamburg, Germany), which previously received the CE mark for clinical applications. The IAP measurement was performed six times (n = 6) at each pressure value (between 0 and 35 mmHg) with different methods and the height of the water column in a bench-top phantom was used as the reference IAP for further interpretations. In addition to the quadruple comparisons, intra- and inter-observer variability of IAP measurements were also calculated. Correlation studies and Bland and Altman’s analyses were performed in addition to the concordance study. Results: The CiMON and Spiegelberg devices showed a greater dynamic range and standard deviation when recording IAPCiM and IAPSPIE compared with IAPSER. In general, the maximum and minimum values of IAP recorded with each device (at each level of IAPH2O) were significantly different from each other. However, the average values were in very good agreement. The highest correlation was observed between IAPSER and IAPH2O, and IAPSER and IAPSPIE (R = 0.99, p = 0.001 for both comparisons and intra- and inter-observer measurements). Although the CiMON and SERENNO systems were in very good agreement with each other, a slightly smaller correlation coefficient was found between them (R = 0.95, p = 0.001, and R = 0.96, p = 0.001 for intra- and inter-observer measurements, respectively). When compared to the gold standard (IAPH2O), Bland and Altman’s analysis showed a mean difference of +0.44, −0.25, and −0.04 mmHg for the intra-observer measurements and +0.18, −0.75, and −0.58 mmHg for the inter-observer measurements for IAPSER, IAPCiM, and IAPSPIE, respectively. IAPSER showed a small positive bias (overestimation), while IAPCiM and IAPSPIE showed a negative bias (underestimation) when compared to IAPH2O. Further statistical analysis showed a concordance coefficient of 100% with an excellent ability of the SERENNO system in tracking IAPH2O changes. Conclusions: Pre-clinical validation of a new IAP monitoring device (SERENNO) showed very promising results when compared with the gold standard and other continuous techniques; however, clinical trials should be followed as the next stage of the validation process. Based on the actual research guidelines, the SERENNO system can be used interchangeably with the gold standard.

Intra-abdominal hypertension and abdominal compartment syndrome in critically ill patients: A narrative review of past, present, and future steps.

Intra-abdominal hypertension is frequently present in critically ill patients and is an independent predictor for mortality. In this narrative review, we aim to provide a comprehensive overview of current insights into intra-abdominal pressure monitoring, intra-abdominal hypertension, and abdominal compartment syndrome. The focus of this review is on the pathophysiology, risk factors and outcome of intra-abdominal hypertension and abdominal compartment syndrome, and on therapeutic strategies, such as non-operative management, surgical decompression, and management of the open abdomen. Finally, future steps are discussed, including propositions of what a future guideline should focus on. Pathological intra-abdominal pressure is a continuum ranging from mild intra-abdominal pressure elevation without clinically significant adverse effects to substantial increase in intra-abdominal pressure with serious consequences to all organ systems. Intra-abdominal pressure monitoring should be performed in all patients at risk of intra-abdominal hypertension. Although continuous intra-abdominal pressure monitoring is feasible, this is currently not standard practice. There are a number of effective non-operative medical interventions that may be performed early in the patient's course to reduce intra-abdominal pressure and decrease the need for surgical decompression. Abdominal decompression can be life-saving when abdominal compartment syndrome is refractory to non-operative treatment and should be performed expeditiously. The objectives of open abdomen management are to prevent fistula and to achieve delayed fascial closure at the earliest possible time. There is still a lot to learn and change. The 2013 World Society of Abdominal Compartment Syndrome guidelines should be updated and multicentre studies should evaluate the effect of intra-abdominal hypertension treatment on patient outcome.

Stretchable Capacitive Pressure Sensing Sleeve Deployable onto Catheter Balloons towards Continuous Intra-Abdominal Pressure Monitoring.

Intra-abdominal pressure (IAP) is closely correlated with intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) diagnoses, indicating the need for continuous monitoring. Early intervention for IAH and ACS has been proven to reduce the rate of morbidity. However, the current IAP monitoring method is a tedious process with a long calibration time for a single time point measurement. Thus, there is the need for an efficient and continuous way of measuring IAP. Herein, a stretchable capacitive pressure sensor with controlled microstructures embedded into a cylindrical elastomeric mold, fabricated as a pressure sensing sleeve, is presented. The sensing sleeve can be readily deployed onto intrabody catheter balloons for pressure measurement at the site. The thin and highly conformable nature of the pressure sensing sleeve captures the pressure change without hindering the functionality of the foley catheter balloon.

Continuous Intra-Abdominal Pressure Measurement: Re-Discovered

Continuous Intra-Abdominal Pressure Measurement: Re-Discovered

Core Body Temperature but Not Intraabdominal Pressure Predicts Postoperative Complications Following Closed-System Hyperthermic Intraperitoneal Chemotherapy (HIPEC) Administration.

Hyperthermic intraperitoneal chemotherapy (HIPEC) following cytoreductive surgery (CRS), performed using closed-abdomen technique (CAT), may affect intraabdominal pressure (IAP). High IAP may increase postoperative complications due to decreased venous return and hypoperfusion to vital organs. Elevated core body temperature (CBT) may cause multiorgan dysfunction. Low IAP or CBT could result in suboptimal HIPEC and potentially translate into early disease recurrence. The aim of the present study is to identify possible correlations between IAP or CBT and postoperative complications. Continuous intraabdominal pressure measurement was performed by intraabdominal catheter. Inflow temperature was set at 44°C, and mean perfusate temperature was 42°C. CBT was measured continuously in the distal esophagus. We compared the rate of postoperative complications between the low IAP group (2-10mmHg, n=28), target IAP group (10-20mmHg, n=71), and high IAP group (20-34mmHg, n=16) as well as with CBT as a continuous variable. 115 patients were included in the study. There was no difference between IAP groups in terms of age, gender, primary diagnosis, operative peritoneal cancer index, CBT, or operative time. There was no correlation between IAP and postoperative complications or with prolonged hospital stay. On multivariate analysis, elevated mean CBT was a positive predictor of postoperative complications (p=0.035). IAP level during closed-abdomen technique HIPEC is not associated with postoperative complications. However, elevated CBT may increase postoperative complications.

A user's guide to intra-abdominal pressure measurement.

The intra-abdominal pressure (IAP) measurement is a key to diagnosing and managing critically ill medical and surgical patients. There are an increasing number of techniques that allow us to measure the IAP at the bedside. This paper reviews these techniques. IAP should be measured at end-expiration, with the patient in the supine position and ensuring that there is no abdominal muscle activity. The intravesicular IAP measurement is convenient and considered the gold standard. The level where the mid-axillary line crosses the iliac crest is the recommended zero reference for the transvesicular IAP measurement; moreover, marking this level on the patient increases reproducibility. Protocols for IAP measurement should be developed for each ICU based on the locally available tools and equipment. IAP measurement techniques are safe, reproducible and accurate and do not increase the risk of urinary tract infection. Continuous IAP measurement may offer benefits in specific situations in the future. In conclusion, the IAP measurement is a reliable and essential adjunct to the management of patients at risk of intra-abdominal hypertension.

EComment. A significance of intra-abdominal pressure in cardiovascular patients

Intra-abdominal hypertension (IAH) is a lethal yet under-appreciated complication of cardiovascular surgery. Dalfino et al. [1] stated that the baseline value of intra-abdominal pressure (IAP) may be an early warning parameter for IAH occurrence. To investigate this statement, last year, we conducted a study in which we assessed correlations among the values of IAP, abdominal perfusion pressure (APP) and clinical scoring systems including the systemic inflammatory response syndrome (SIRS), multiple organ dysfunction score (MODS) and Acute Physiology and Chronic Health Evaluation (APACHE II) in patients after open surgical repair of abdominal aneurysms. The IAP was measured in a non-invasive manner via the urinary bladder filled up with 100 ml saline solution, through the previously drained and clamped standard urinary catheter [2]. The actual pressure was transmitted to a manometer into the mid-axillary line. A pressure above 15 mmHg is considered elevated [3]. Of 50 studied patients with a survival rate of 50%, we found IAP values over 15 mmHg in 26 patients (52%). The non-parametric statistical Kruskal-Wallis test was used for comparison of survivors and non-survivors distribution of IAP values. The median for non-survivors was 18 (range 6-30), and for survivors the median was 15 (range 6-36) with significance P < 0.009. The same statistic was applied for MODS values where the median for non-survivors was 3 (range 0-6), and for survivors 1 (range 0-3), P < 0.0072. For the APACHE II score the non-survivors median was 18 (range 0-34), and survivors 9 (range 2-23), P < 0.0067. We did not find any significance in relation to the IAP values and disease severity scores in linear regression statistics. On the other hand, the linear regression correlation demonstrated the comparison of APP with disease severity scores as follows: a) APP versus SIRS-correlation coefficient (r = -0.43, P < 0.05); b) APP versus MODS (r = -0.49, P < 0.05); c) APP versus APACHE II (r = -0.47, P < 0.05). According to our results, we conclude that the measurement of IAP might have a predictive value in cardiovascular surgical patient's survival rates, but the APP may be a better indicator of IAH severity. Measurement of IAP is widely accepted, inexpensive and a simple monitoring tool for IAH [4]. However, it is an intermittent measurement and therefore not always appropriate as an indicator for the organ dysfunction that typifies IAH. The other problem with IAP is that it is an indicator of the syndrome (defined by IAP as abdominal compartment syndrome), not a real predictor: when IAP is pathologically elevated and organ dysfunctions are imminent, prevention of the syndrome is a faint hope. Authors stated that their findings encourage further studies to define the role of continuous IAP monitoring and therapeutic strategies. According to the results presented by Dalfino et al., which support our results we could conclude that further investigations of the predictors of IAH in cardiovascular patients must include both physiological measurements and resuscitative interventions. Conflict of interest: none declared

Integration of inspiratory and expiratory intra-abdominal pressure: a novel concept looking at mean intra-abdominal pressure.

BackgroundThe intra-abdominal pressure (IAP) is an important clinical parameter that can significantly change during respiration. Currently, IAP is recorded at end-expiration (IAPee), while continuous IAP changes during respiration (ΔIAP) are ignored. Herein, a novel concept of considering continuous IAP changes during respiration is presented.MethodsBased on the geometric mean of the IAP waveform (MIAP), a mathematical model was developed for calculating respiratory-integrated MIAP (i.e. ), where 'i' is the decimal fraction of the inspiratory time, and where ΔIAP can be calculated as the difference between the IAP at end-inspiration (IAPei) minus IAPee. The effect of various parameters on IAPee and MIAPri was evaluated with a mathematical model and validated afterwards in six mechanically ventilated patients. The MIAP of the patients was also calculated using a CiMON monitor (Pulsion Medical Systems, Munich, Germany). Several other parameters were recorded and used for comparison.ResultsThe human study confirmed the mathematical modelling, showing that MIAPri correlates well with MIAP (R2 = 0.99); MIAPri was significantly higher than IAPee under all conditions that were used to examine the effects of changes in IAPee, the inspiratory/expiratory (I:E) ratio, and ΔIAP (P <0.001). Univariate Pearson regression analysis showed significant correlations between MIAPri and IAPei (R = 0.99), IAPee (R = 0.99), and ΔIAP (R = 0.78) (P <0.001); multivariate regression analysis confirmed that IAPee (mainly affected by the level of positive end-expiratory pressure, PEEP), ΔIAP, and the I:E ratio are independent variables (P <0.001) determining MIAP. According to the results of a regression analysis, MIAP can also be calculated asMIAP=-0.3+IAPee+0.4⋅ΔIAP+0.5⋅IE.ConclusionsWe believe that the novel concept of MIAP is a better representation of IAP (especially in mechanically ventilated patients) because MIAP takes into account the IAP changes during respiration. The MIAP can be estimated by the MIAPri equation. Since MIAPri is almost always greater than the classic IAP, this may have implications on end-organ function during intra-abdominal hypertension. Further clinical studies are necessary to evaluate the physiological effects of MIAP.

A Novel Method (CiMON) for Continuous Intra-Abdominal Pressure Monitoring: Pilot Test in a Pig Model.

Background. Intravesical pressure (IAPivp) measurement is considered to be the gold standard for assessment of intra-abdominal pressure (IAP). This study evaluated a new minimally invasive IAP monitoring device (CiMON) against three other devices in a wide range of clinically relevant IAP and in different body positions in healthy pigs. Methods. The CiMON catheter (IAPCiM) and another balloon-tipped catheter (IAPspie) were positioned into the stomach. Fluid-filled catheters were used for direct intraperitoneal (IAPdir) and IAPivp measurement. Both in supine and 25° head-of-bed positions, IAP was increased from baseline to 30 mmHg. At every IAP level, 4 IAP measurements were recorded simultaneously. Mean differences and the limits of agreement were calculated. Results. Bias between IAPCiM and IAPspie was nearly zero with very good agreement, both in supine and 25° position. In supine position, IAPCiM slightly overestimated IAPivp and IAPdir by 1.5 and 2.1 mmHg with reasonable agreement. In 25° position, IAPCiM underestimated IAPivp and IAPdir by 1.0 and 0.5 mmHg, again with reasonable agreement. Conclusions. Agreement between IAPCiM and IAPspie was very good, while good-to-moderate agreement exists between IAPCiM and IAPdir or IAPivp. Simplicity, continuous monitoring, and the combination with a feeding tube should lead to further clinical studies, evaluating this new CiMON device.

Evaluating intra-abdominal pressures in a porcine model of acute lung injury by using a wireless motility capsule.

SummaryBackgroundIntra-vesical pressure measurement as the reference standard for assessing intra-abdominal pressures is mainly indirect and discontinuous. We therefore evaluated a motility capsule for continuous intra-abdominal pressure measurement in an animal model with a high probability for capillary leakage and intestinal edema.Material/MethodsMotility capsules were inserted into the stomachs of 8 anesthetized and ventilated pigs. Stomach pH, pressure, and temperature data were wirelessly transmitted to a recorder attached to each animal’s abdomen. Intra-gastric pressures measured by the capsule were compared to intra-vesical pressures measured by a pressure transducer system.ResultsThe intra-abdominal pressures ranged from 3 to 15 mmHg (7.8±2.4 mmHg [mean ±SD]) measured via the bladder. The capsule pressure recordings ranged from 1 to 3 mmHg (1.7±0.5 mmHg [mean ±SD]). Bland-Altman analysis revealed an unacceptable bias between the 2 methods. The test bias was 6.2 (±1.4) mmHg and the limits of agreement were from 3.3 to 8.9 mmHg.ConclusionsPressures in the stomach as measured by motility capsule underestimated the intra-vesical pressures. Discrepancies between gastric and intra-vesical pressures could be caused by gastric dilatation or different position of the 2 devices to the zero reference point.

Development of a novel intra-vaginal transducer with improved dynamic response.

Limitations of standard clinical pressure transducers have hampered our ability to provide reliable measurements of intra-abdominal pressure (IAP) during physical activities. To overcome these limitations, a novel intravaginal transducer (IVT) capable of accurate, reliable, and continuous IAP measurements during normal activity was developed. The design was validated through comparison with standard clinical pressure transducers in both bench top and clinical tests. The IVT demonstrated an improved dynamic response when compared to a standard rectal balloon catheter. Additionally, the radially symmetric design allows for accurate measurement within non-fluid-filled tissue cavities and simple placement within the vaginal canal. This is an advantage over sensor-tipped transducers which are only reliable in fluid-filled compartments. The IVT design presented here is preliminary to a wireless version that will allow for IAP measurement during activities outside the clinic.

Validation and Experience With a Simple Continuous Intra-abdominal Pressure Measurement Technique in a Multidisciplinary Medical/Surgical Critical Care Unit

Raised intra-abdominal pressure (IAP) or intra-abdominal hypertension (IAH) may induce many adverse effects including the abdominal compartment syndrome. We evaluated a new technique for continuous monitoring of intra-abdominal pressure (CIAP) using a standard three-way bladder catheter in a diverse group of intensive care unit patients. CIAP measured using a standard three-way bladder catheter was compared with five standard intermittent IAP (IIAP) measurements in 79 patients. Mean (standard deviation) CIAP was identical (15.4 mm Hg [5.8]) for CIAP and IIAP one minute after saline injection. Mean differences between methods were less than 1 mm Hg, and similar whether IIAP was measured at 1 minute, 2 minutes, 3 minutes, 4 minutes, or 5 minutes. Bland-Altman analysis comparing CIAP and IIAP (1 minute) revealed a mean difference (95% confidence interval) of -0.06 mm Hg (-0.51, 0.39). Limits of agreement were -4.12 mm Hg to 4.00 mm Hg. Considering gradations of IAH defined by the World Society of the Abdominal Compartment Syndrome, CIAP was sensitive for detecting slightly elevated IAP (>11 mm Hg) but is less sensitive for distinguishing between higher grades of IAH (e.g., pressures >20 mm Hg or 25 mm Hg). Limits of agreement were best for patients with IAP less than 20 mm Hg, surgical or traumatic diagnoses and for patients with BMI less than 26. Overall, CIAP is an accurate and simple means of measuring IAP when compared with the current standardized method. Elevated CIAP measurements should be confirmed with IIAP measurements if accurate grading is required until further validation and experience is obtained.

Comparison of intermittent and continuous intra-abdominal pressure monitoring using an in vitro model

Intra-abdominal pressure (IAP) is increasingly being considered as an important physiologic parameter to be measured in critically ill patients. Traditional methods of monitoring IAP rely on intermittent IAP (IIAP) measurements using indwelling bladder catheters. Recently, a method of continuous IAP (CIAP) monitoring has been developed using a three-way bladder catheter. This study evaluates the reliability of IIAP and CIAP measurement techniques using an in vitro model. An in vitro model of the abdomen was constructed using a 50 l container with a 100 ml infusion bag at the base to simulate a bladder. A three-way catheter tip was centered within the infusion bag filled with 50 ml saline. To simulate IAP the container was filled with water at 5 cm H(2)O increments from 10 to 25 cm H(2)O. Pressures were recorded by observers from a bedside monitor interfaced with a three-way Foley catheter using alternating intermittent and continuous techniques. Each subject was blinded to the known pressure values. Descriptive statistics and a generalised estimating equation (GEE) was used to describe the relationship of IIAP and CIAP to known pressures. One hundred and thirty-two (132) observations were made by 20 subjects for both IIAP and CIAP estimates. In 45.5% of IIAP measures, the estimate was correct, and it was never more than 1 cm H(2)O different from the actual. Similarly, in 38.6% of CIAP measures, the estimate was correct, and was never more than 2 cm H(2)O from the actual. The GEE regression coefficients comparing known pressures with IIAP and CIAP were 1.007 and 0.976 respectively. The minimum and maximum pressure deviations never exceeded more than 1.3 cm H(2)O from the actual. Intermittent IAP and CIAP are both reliable and reproducible methods to measure IAP in an in vitro model. There exists a direct and significant association between both measurements and the actual value. Neither measure was shown to be superior.

Continuous intra-abdominal pressure monitoring: this is the way to go!

Continuous intra-abdominal pressure monitoring: this is the way to go!

A Novel Concept for the Surgical Anatomy of the Perineal Body

Perineal body is considered by investigators as a fibromuscular structure that is the site of insertion of perineal muscles. We investigated the hypothesis that perineal body is the site across which perineal muscles pass uninterrupted from one side to the other. Perineal body was studied in 56 cadaveric specimens (46 adults, 10 neonatal deaths) by direct dissection with the help of magnifying loupe, fine surgical instruments, and bright light. Perineal body consisted of three layers: 1) superficial layer, which consisted of fleshy fibers of the external anal sphincter extending across perineal body to become the bulbospongiosus muscle; 2) tendinous extension of superficial transverse perineal muscle crossing perineal body to contralateral superficial transverse perineal muscle, with which it formed a criss-cross pattern; and 3) tendinous fibers of the deep transverse perineal muscle; the fibers crossing perineal body decussated in criss-cross pattern with the contralateral deep transverse perineal muscle. A relation of levator ani or puborectalis muscles to perineal body could not be identified. Perineal body (central perineal tendon) is not the site of insertion of perineal muscles but the site along which muscle fibers of these muscles and the external anal sphincter pass uninterrupted from one side to the other. Such a free passage from one muscle to the other seems to denote a "digastric pattern" for the perineal muscles. Perineal body is subjected to injury or continuous intra-abdominal pressure variations, which may eventually result in perineocele, enterocele, or sigmoidocele.