Variations In Intra-abdominal Pressure Research Articles

An Introduction to Ventra: A Programmable Abdominal Phantom for Training, Educational, Research, and Development Purposes.

Intra-abdominal pressure (IAP) is a critical parameter in the care of critically ill patients, as elevated IAP can lead to reduced cardiac output and organ perfusion, potentially resulting in multiple organ dysfunction and failure. The current gold standard for measuring IAP is an indirect technique via the bladder. According to the Abdominal Compartment Society's Guidelines, new measurement methods/devices for IAP must be validated against the gold standard. This study introduces Ventra, an abdominal phantom designed to simulate different IAP levels, abdominal compliance, respiration-related IAP variations, and bladder dynamics. Ventra aims to facilitate the development and validation of new IAP measurement devices while reducing reliance on animal and cadaveric studies. Additionally, it offers potential applications in training and education for biomedical engineering students. This study provides a thorough explanation on the phantom's design and fabrication, which provides a low-cost solution for advancing IAP measurement research and education. The design concept, technical aspects, and a series of validation experiments determining whether Ventra is a suitable tool for future research are presented in this study. Ventra's performance was evaluated through a series of validation tests using a pressure gauge and two intra-gastric (Spiegelberg and CiMON) and two intra-bladder (Accuryn and TraumaGuard) pressure measurement devices. The mean and standard deviation of IAP recordings by each device were investigated. Bland-Altman analysis was used to evaluate bias, precision, limits of agreement, and percentage error for each system. Concordance analysis was performed to assess the ability of Ventra in tracking IAP changes. The phantom demonstrated excellent agreement with reference pressure measurements, showing an average bias of 0.11 ± 0.49 mmHg. A concordance coefficient of 100% was observed for the phantom as well. Ventra accurately simulated different abdominal compliances, with higher IAP values resulting in lower compliance. Abdominal volume changes showed a bias of 0.08 ± 0.07 L/min, and bladder fill volume measurements showed an average difference of 0.90 ± 4.33 mL for volumes ranging from 50 to 500 mL. The validation results were in agreement with the research guidelines of the world abdominal society. Ventra is a reliable tool that will facilitate the development and validation of new IAP measurement devices. It is an effective educational tool for biomedical engineering students as well.

Is There a Direct Effect Between the Plication of the Myoaponeurotic Layer and the Force of Inspiratory and Expiratory Muscles After Abdominoplasty?

Abdominoplasty may generate an increase in the intra-abdominal pressure (IAP) and consequently an alteration in the pulmonary ventilation. The purpose of this study was to evaluate the potential alterations in the maximal static inspiratory pressure (MIP) and maximal static expiratory pressure (MEP) after abdominoplasty. Thirty-three female patients, aged between 18 and 60, with type III/B Nahas abdominal deformity that underwent abdominoplasty with plication of the anterior rectus and external oblique aponeurosis were selected. The MIP and MEP were measured using a mouthpiece. This is a simple way to indirectly gauge inspiratory and expiratory muscle strength. Measurements were performed before surgery and on the 2nd, 7th, 15th, and 180th postoperative day. In addition, IAP was measured before abdominoplasty and after the placement of compression garment. The MIP and MEP were compared using analysis of variance, followed by the Bonferroni multiple comparison test pairing the different points in time. Paired Student's t test was used for comparing IAP measurements. Pearson's correlation test was used to compare MIP and MEP variations with IAP variation. Results were considered statistically significant when P ≤ 0.05. A decrease was observed in MEP on the 2nd day, with a return close to normal values on the 15th day. In opposition MIP had a surprisingly increase on the 15th postoperative day (129 cmH2O), normalizing 180 days after the operation. A leap in IAP values was revealed at the end of the surgical procedure. It was not possible to establish a positive correlation between the increase of IAP and the alterations of MIP and MEP. There is a decrease in maximum expiratory pressure on the very early postoperative day (2nd postoperative day) and an increase in maximum inspiratory pressure on the 15th postoperative day in patients who underwent abdominoplasty. There was no correlation between the IAP and maximum respiratory pressure variations, both inspiratory and expiratory.

Assessment of the Smartpill, a Wireless Sensor, as a Measurement Tool for Intra-Abdominal Pressure (IAP).

Background: The SmartPill, a multisensor ingestible capsule, is marketed for intestinal motility disorders. It includes a pressure sensor, which could be used to study intra-abdominal pressure (IAP) variations. However, the validation data are lacking for this use. Material and Methods: An experimental study was conducted on anesthetized pigs with stepwise variations of IAP (from 0 to 15 mmHg by 3 mmHg steps) generated by laparoscopic insufflation. A SmartPill, inserted by endoscopy, provided intragastric pressure data. These data were compensated to take into account the intrabdominal temperature. They were compared to the pressure recorded by intragastric (IG) and intraperitoneal (IP) wired sensors by statistical Spearman and Bland-Altmann analysis. Results: More than 4500 pressure values for each sensor were generated on two animals. The IG pressure values obtained with the SmartPill were correlated with the IG pressure values obtained with the wired sensor (respectively, Spearman ρ coefficients 0.90 ± 0.08 and 0.72 ± 0.25; bias of -28 ± -0.3 mmHg and -29.2 ± 0.5 mmHg for pigs 1 and 2). The intragastric SmartPill values were also correlated with the IAP measured intra-peritoneally (respectively, Spearman ρ coefficients 0.49 ± 0.18 and 0.57 ± 0.30; bias of -29 ± 1 mmHg and -31 ± 0.7 mmHg for pigs 1 and 2). Conclusions: The SmartPill is a wireless and painless sensor that appears to correctly monitor IAP variations.

Full-field in vivo experimental study of the strains of a breathing human abdominal wall with intra-abdominal pressure variation

The presented study aims to assess the mechanical behaviour of the anterior abdominal wall based on an in vivo experiment on humans. Full-field measurement of abdominal wall displacement during changes of intra-abdominal pressure is performed using a digital image correlation (DIC) system. Continuous measurement in time enables the observation of changes in the strain field during breathing. The understanding of the mechanical behaviour of a living human abdominal wall is important for the proper design of surgical meshes used for ventral hernia repair, which was also a motivation for the research presented below.The research refers to the strain field of a loaded abdominal wall and presents the evolution of principal strains and their directions in the case of 12 subjects, 8 male and 4 female. Peritoneal dialysis procedure allows for the measurement of intra-abdominal pressure after fluid introduction.High variability among patients is observed, also in terms of principal strain direction. Subjects exhibit intra-abdominal pressure of values from 11 to 21 cmH2O. However, the strain values are not strongly correlated with the pressure value, indicating variability of material properties.

OC-020 QUANTITATIVE EVALUATION OF THE ABDOMINAL WALL MECHANICAL BEHAVIOR BY A NEW CONNECTED ABDOMINAL BINDER: A PRELIMINARY STUDY

Abstract Aim Abdominal wall hernias result from a mechanical conflict between forces acting on the wall (mainly intra-abdominal pressure (IAP)) and its ability to deform. An abdominal binder instrumented with sensors has been developed to non-invasively quantify the deformation during straining. Methods A prospective study was conducted on eight healthy subjects. External deformations were evaluated by a patented connected binder instrumented with resistive sensors covering anterolateral area. IAP was evaluated by intragastric ingested sensor (SmartPill™, Medtronic), and wall muscles deformation by dynamic MRI (semi-automated segmentation method applied to rectus abdominis (RA) and lateral muscle (LM)). The relationship between these signals has been investigated during Valsalva maneuver. Results The binder provided time-related mapping of the abdominal deformation. Two different patterns were individualized corresponding to RA and LM areas. Deformation rate (mean 1.21mV/s for RA and 1.66mV/s for LM) and maximum signal (mean 3.03mV for RA and 4.24mV for LM) were recorded. These binder patterns were both correlated with the deep deformation in abdominal muscles observed in MRI (Pearson R=0.89 for RA, and R=0.94 for LM; p<0.005). The binder patterns were also significantly correlated with the IAP variation (Pearson R=0.98 for RA and R=0.99 for LM; p<0.005). Conclusion This non-invasive connected and instrumented abdominal binder simply and quickly reflects the abdominal wall muscles deformation and IAP variation during Valsalva maneuver. A larger study is needed to investigate inter-individual variability, and to evaluate the links between quantitative mechanical behavior and surgical outcomes during hernia surgery.

A better understanding of daily life abdominal wall mechanical solicitation: Investigation of intra-abdominal pressure variations by intragastric wireless sensor in humans

Intra-abdominal pressure (IAP), as the main mechanical load applied to the abdominal wall, is decisive in the occurrence of ventral hernia. The objective of the study was to propose a comprehensive evaluation of IAP based on a limited risk and discomfort method. A prospective study was carried out in 20 healthy volunteers. The intragastric pressure, validated for estimating IAP, was assessed by an ingestible pressure sensor. Volunteers realized a set of supervised exercises, then resumed their daily activities with the pressure continuously recorded until gastric emptying. Coughing and jumping exercises resulted in the highest IAP levels with maximum peaks of 65 ± 35 and 67 ± 31 mmHg and pressure rates of 121 and 114 mmHg.s−1 respectively. The position did not affect the IAP variation. Men had significantly higher pressure values for pushing against a wall (P < 0.01), Valsalva maneuver and legs raising (P<0.05) exercises. During daily life, IAP greater than 50, 100, and 150 mmHg occurred on average five times, twice, and once per hour, respectively. This study provides a real-life characterization of the IAP allowing the quantification of mechanical solicitation applied to the abdominal wall and the identification of risk situations for the occurrence of ventral hernias.

Bladder Base Displacement during Abdominal Muscles Contraction and Functional Activities in Primiparous Women Assessed by Transabdominal Ultrasound: A Descriptive Study.

This study described the response of the bladder base (BB) by transabdominal ultrasound in primiparous women during movements that activate the abdominopelvic cavity musculature and cause variations in intra-abdominal pressure (IAP). A descriptive cross-sectional study was conducted in 64 primiparous women at eight weeks after uncomplicated delivery. BB displacement was measured using a 5-MHz convex transducer in a suprapubic position. Participants were asked to perform the isolated contraction of pelvic floor musculature (PFM) and transverse abdominis (TrA), cough at high lung volume and trunk flexion with and without maximal voluntary contraction of PFM. PFM contraction elevated the BB in all but one participant, whereas TrA contraction caused the BB to ascend in 56% of the women and descend in the rest; their combined contraction rose the BB in 65% of the women although the effect was greater with only PFM contraction (p < 0.01). The BB descended in all participants during coughing and trunk flexion although the descent was inferior with the joint maximal voluntary contraction of PFM (p < 0.01). In conclusion, TrA contraction must be assessed individually in puerperal women since its effect on the BB varies among subjects. During movements increasing IAP, such as coughing or curl-ups, the anticipatory contraction of PFM reduces bladder descent although not sufficiently to counteract bladder displacement.

O43 INTRA-ABDOMINAL PRESSURE VARIATIONS IN HUMANS DURING PHYSICAL EXERCISES AND DAILY LIFE BY INTRAGASTRIC WIRELESS SENSOR

Abstract Aim The conflict between the intra-abdominal pressure (IAP) applied to the abdominal wall and its resistance determines the occurrence of ventral hernia. Knowledge about IAP variation in everyday life is limited and mainly obtained by invasive methods. The objective of the study is to propose a comprehensive evaluation of IAP based on a limited risk and discomfort method. Material and Methods A prospective study was carried out in 20 healthy volunteers. The intragastric pressure, validated for estimating IAP, was assessed by an ingestible pressure sensor*. Volunteers realized a set of supervised exercises, including breathing, apnea after calm exhalation and seven muscle contraction stereotyped exercises in three different positions (supine, sitting, standing). Then the volunteers resumed their daily activities with the pressure continuously recorded until gastric emptying. Pressure variations and rates were computed. Results The highest IAP levels were reached during coughing and jumping. Maximum peaks were respectively 65 ± 35 and 67 ± 31 mmHg with pressure rates of 121 and 114 mmHg.s−1 for these two exercises. The position did not affect the IAP variation. Men had significantly higher pressure values for pushing against a wall (P &amp;lt; 0.01), Valsalva maneuver and legs raising (P &amp;lt; 0.05) exercises. During daily life, peaks greater than 50, 100, and 150 mmHg occurred on average five times, twice, and once per hour, respectively. Conclusions This study provides a real-life characterization of IAP allowing the quantification of mechanical solicitation applied to the abdominal wall and the identification of risk situations for the occurrence of ventral hernias. * (SmartPill™, Medtronic, Minneapolis, MN, U.S.A)

Severe Intraabdominal Hypertension in Critically Ill COVID-19 Patients With Acute Kidney Injury

Severe Intraabdominal Hypertension in Critically Ill COVID-19 Patients With Acute Kidney Injury

Numerical Investigation of Intra-abdominal Pressure Effects on Spinal Loads and Load-Sharing in Forward Flexion.

The intra-abdominal pressure (IAP), which generates extensor torque and unloads the spine, is often neglected in most of the numerical studies that use musculoskeletal (MSK) or finite element (FE) spine models. Hence, the spinal loads predicted by these models may not be realistic. In this work, we quantified the effects of IAP variation in forward flexion on spinal loads and load-sharing using a novel computational tool that combines a MSK model of the trunk with a FE model of the ligamentous lumbosacral spine. The MSK model predicted the trunk muscle and reaction forces at the T12-L1 junction, with or without the IAP, which served as input in the FE model to investigate the effects of IAP on spinal loads and load-sharing. The findings confirm the unloading role of the IAP, especially at large flexion angles. Inclusion of the IAP reduced global muscle forces and disc loads, as well as the intradiscal pressure (IDP). The reduction in disc loads was compensated for by an increase in ligament forces. The IDP, as well as the strain of the annular fibers were more sensitive to the IAP at the upper levels of the spine. Including the IAP also increased the ligaments' load-sharing which reduced the role of the disc in resisting internal forces. These results are valuable for more accurate spinal computational studies, particularly toward clinical applications as well as the design of disc implants.

3D surface imaging of abdominal wall muscular contraction

Background and ObjectiveThe biomechanical analysis of the abdominal wall should take into account muscle activation and related phenomena, such as intra-abdominal pressure variation and abdomen surface deformation. The geometry of abdominal surface and its deformation during contraction have not been extensively characterized, while represent a key issue to be investigated. MethodsIn this work, the antero-lateral abdominal wall surface of ten healthy volunteers in supine position is acquired via laser scanning in relaxed conditions and during abdominal muscles contraction, repeating each acquisition six times. The average relaxed and contracted abdominal surfaces are compared for each subject and displacements measured. ResultsMuscular activation induces raising in the region adjacent to linea alba along the posterior-anterior direction and a simultaneous lowering along lateral-medial direction of the abdominal wall sides. Displacements reach a maximum value of 12.5 mm for the involved subjects. The coefficient of variation associated to the abdomen surface measurements in the same configuration (relaxed or contracted) is below 0.75%. Non-parametric Mann-Whitney U test highlights that the differences between relaxed and contracted abdominal wall surfaces are significant (p < 0.01). ConclusionsLaser scanning is an accurate and reliable method to evaluate surface changes on the abdominal wall during muscular contraction. The results of this experimental activity can be useful to validate numerical models aimed at describing abdominal wall biomechanics.

Impact of valve-less vs. standard insufflation on pneumoperitoneum volume, inflammation, and peritoneal physiology in a laparoscopic sigmoid resection experimental model.

Standard insufflators compensate for intra-abdominal pressure variations with pressure spikes. Our aim was to evaluate the impact of a stable, low-pressure pneumoperitoneum induced by a valve-less insufflator, on working space, hemodynamics, inflammation, and peritoneal physiology, in a model of laparoscopic sigmoid resection. Twelve pigs (47 ± 3.3 kg) were equipped for invasive hemodynamic monitoring and randomly assigned to Standard (n = 6) vs. valve-less (n = 6) insufflation. Animals were positioned in a 30° Trendelenburg on a CT scan bed. A low-pressure pneumoperitoneum (8mmHg) was started and duration was set for 180min. Abdominal CT scans were performed, under neuromuscular blockade, before, immediately after, and 1 and 3h after insufflation. Pneumoperitoneum volumes were calculated on 3D reconstructed CT scans. After creation of a mesenteric window, capillary blood was obtained by puncturing the sigmoid serosa and local lactatemia (mmol/L) was measured using a handheld analyzer. Surgical resection was performed according to the level of lactates, in order to standardize bowel stump perfusion. IL-1 and IL-6 (ng/mL) were measured repeatedly. The peritoneum was sampled close to the surgical site and distantly for the oxygraphic assessment of mitochondrial respiration. A pathologist applied a semi-quantitative score to evaluate the anastomosis. Mean arterial pressure, pulse, body temperature, oximetry, systemic lactatemia, and local lactates were similar. IL-6 was lower in the valve-less group, reaching a statistically significant difference after 3h of insufflation (64.85 ± 32.5 vs. 133.95 ± 59.73; p = 0.038) and 48h (77.53 ± 68.4 vs. 190.74 ± 140.79; p = 0.029). Peritoneal mitochondrial respiration was significantly increased after the survival period, with no difference among the groups. The anastomoses in the valve-less group demonstrated a lower acute (p = 0.04) inflammatory infiltration. The mean anterior posterior thickness was slightly, yet significantly higher in the valve-less group, on all post-insufflation CT scans. Valve-less insufflation achieved a slightly higher working space and a lower systemic and localized inflammatory response in this experimental setting.

Hernia recurrence long term follow-up after open procedures of abdominal wall plasty – Prospective study including 142 patients

Abstract Background The incisional hernia continues to be a frequent complication of laparotomies. The purpose of study is the analysis of hernia disease relapse after one year after different open plasties methods of the abdominal wall. Material and methods A prospective longitudinal study was performed that included 142 patients. An analysis was performed on the individual data, the level of obesity, intra-surgical variations in intra-abdominal pressure, the intensity of post-surgical pain, the post-surgical complications, and the types of plasties of abdominal wall, simple and with polypropylene mesh. Results The analysis of studied group showed a general rate of relapse of 16.9%, and within the 4 procedures, 40.74% in the case of simple plasties, of 16.07% after the only plasties, 6.97% after the retro-muscular plasties, and 6.25% after the full substitution of parietal defect. On analysing the collected, hernia relapse was statistically significantly related to the level of obesity, variations in intra-abdominal pressure, post-surgical pain, and the type of procedure performed. Conclusions Hernia is a frequent complication of laparotomies. Hernia relapse was more frequent in the case of simple plasties. Among the mesh procedures, the onlay plasty showed a higher rate of relapse and post-surgical complications. Hernia relapse was more frequent in the case of variations of intra-abdominal pressure, and with increased post-surgical pain. The use of an echography examination may increase the accuracy of the presence of hernia disease.

Seguimiento remoto de la recaída de hernia después de procesos abiertos de plastia de la pared abdominal– estudio prospectivo que incluye 142 pacientes

BackgroundThe incisional hernia continues to be a frequent complication of laparotomies. The purpose of study is the analysis of hernia disease relapse after one year after different open plasties methods of the abdominal wall. Material and methodsA prospective longitudinal study was performed that included 142 patients. An analysis was performed on the individual data, the level of obesity, intra-surgical variations in intra-abdominal pressure, the intensity of post-surgical pain, the post-surgical complications, and the types of plasties of abdominal wall, simple and with polypropylene mesh. ResultsThe analysis of studied group showed a general rate of relapse of 16.9%, and within the 4 procedures, 40.74% in the case of simple plasties, of 16.07% after the only plasties, 6.97% after the retro-muscular plasties, and 6.25% after the full substitution of parietal defect. On analysing the collected, hernia relapse was statistically significantly related to the level of obesity, variations in intra-abdominal pressure, post-surgical pain, and the type of procedure performed. ConclusionsHernia is a frequent complication of laparotomies. Hernia relapse was more frequent in the case of simple plasties. Among the mesh procedures, the onlay plasty showed a higher rate of relapse and post-surgical complications. Hernia relapse was more frequent in the case of variations of intra-abdominal pressure, and with increased post-surgical pain. The use of an echography examination may increase the accuracy of the presence of hernia disease.

Effect of transgastric natural orifice transluminal endoscopic surgery peritoneoscopy on abdominal organ microcirculation: an experimental controlled study

On-demand insufflation during endoscopic peritoneoscopy causes wide variations in intra-abdominal pressure. Its effects on splanchnic microcirculation may differ from those of steady intra-abdominal pressure, because pressure characteristics affect crucial intravascular hemodynamic forces--pressure and shear--adapting flow to local metabolic needs. Our aim was to assess the effect of natural orifice transluminal endoscopic surgery (NOTES) peritoneoscopy on splanchnic microcirculatory blood flow. Twenty-one swine were randomized to the following: cholecystectomy by transgastric NOTES (n = 8), cholecystectomy by standard laparoscopy (Lap) (n = 8), and a sham group (n = 5). During NOTES, CO2 was manually insufflated with a maximum allowed pressure of 30 mm Hg. In the Lap group, intra-abdominal pressure was maintained at 14 mm Hg. Systemic hemodynamics were measured, and microcirculatory blood flow was quantified by using colored microspheres. Mean intra-abdominal pressure was lower in NOTES than in the Lap group (P = .038). In both groups, cardiac index and preload remained unchanged, whereas systemic vascular resistances increased over time, with a lesser increase in the Lap group (2-way analysis of variance; P = .041). In pneumoperitoneum groups, microcirculatory blood flow decreased similarly in the renal medulla, stomach, small bowel, colon, and mesocolon by 30%, 45%, 34%, 32%, and 37%, respectively. In NOTES, there was a greater microcirculatory blood flow decrease in the renal cortex (NOTES 41% vs Lap 35%; P = .044) and mesentery (NOTES 44% vs Lap 38%; P = .041). These findings suggest that both types of pneumoperitoneum have similar physiologic effects on microcirculatory blood flow. However, on-demand pneumoperitoneum (NOTES group) caused a greater microcirculatory blood flow decrease in areas with low metabolic needs, redistributing blood flow toward metabolically active areas.

The role of abdominal compliance, the neglected parameter in critically ill patients - a consensus review of 16. Part 2: measurement techniques and management recommendations.

The recent definitions on intra-abdominal pressure (IAP), intra-abdominal volume (IAV) and abdominal compliance (Cab) are a step forward in understanding these important concepts. They help our understanding of the pathophysiology, aetiology, prognosis, and treatment of patients with low Cab. However, there is still a relatively poor understanding of the different methods used to measure IAP, IAV and Cab and how certain conditions may affect the results. This review will give a concise overview of the different methods to assess and estimate Cab; it will list important conditions that may affect baseline values and suggest some therapeutic options. Abdominal compliance (Cab), defined as a measure of the ease of abdominal expansion, is measured differently than IAP. The compliance of the abdominal wall is only a part of the total abdominal pressure-volume (PV) relationship. Measurement or estimation of Cab is difficult at the bedside and can only be done in a case of change (removal or addition) in IAV. The different measurement techniques will be discussed in relation to decreases (ascites drainage, haematoma evacuation, gastric suctioning) or increases in IAV (gastric insufflation, laparoscopy with CO₂ pneumoperitoneum, peritoneal dialysis). More specific techniques using the interactions between the thoracic and abdominal compartment during positive pressure ventilation will also be discussed (low flow PV loop, respiratory IAP variations, respiratory abdominal variation test, mean IAP and abdominal pressure variation), together with the concept of the polycompartment model. The relation between IAV and IAP is linear at low IAV and becomes curvilinear and exponential at higher volumes. Specific conditions in relation to increased (previous pregnancy or laparoscopy, gynoid fat distribution, ellipse-shaped internal abdominal perimeter) or decreased Cab (obesity, fluid overload, android fat distribution, sphere-shaped internal abdominal perimeter) will be discussed as well as their impact on baseline IAV, IAP, reshaping capacity and abdominal workspace volume. Finally, we suggest possible treatment options in situations of unadapted IAV according to existing Cab, which results in high IAP. A large overlap exists between the treatment of patients with abdominal hypertension and those with low Cab. The Cab plays a key role in understanding the deleterious effects of unadapted IAV on IAP and end-organ perfusion and function. If we can identify patients with low Cab, we can anticipate and select the most appropriate surgical treatment to avoid complications such as IAH or ACS.

Abdominal compliance, linearity between abdominal pressure and ascitic fluid volume.

Background:Drainage of ascitic fluid is a common practice in order to relief the respiratory discomfort of patients.Aim:To determine the relation between the intra-abdominal pressure (IAP) and extracted volume of the ascitic fluid, in order to calculate abdominal compliance (Cabd).Settings and Design:A study was designed at AHEPA University Hospital and analysed with prospectively collected data.Materials and Methods:Fifteen patients with tension ascites that had transcutaneous drainage with a wide catheter. The ascitic fluid removed was measured, while the IAP and a Visual Analogue Scale (VAS) score for dyspnea were recorded before and 15 min after the puncture. Cabd was calculated.Statistical Analysis:The data were analysed with descriptive statistics, paired Student's t-test and Pearson coefficiency.Results:The predrainage IAP was 18.26 mmHg (SD 1.67 mmHg), while the postdrainage was 14.46 mmHg (SD 1.34 mmHg) (P<0.001). The mean volume of ascitic fluid removed was 1624 mL (SD 861 mL). Cabd after drainage was 414.01 mL/mmHg (SD 139.15 mL/mmHg). A linear correlation was found between ascitic fluid removal and IAP variations. The dyspnea VAS score was 7.5 (SD=0.8) before the drainage and 4.3 (SD=1.0) after the drainage (P<0.001).Conclusions:The drainage of ascitic fluid reduces IAP, facilitating in this way respiration. Moreover, IAP variation seems to be in linear relation with the volume of ascitic fluid removed. This linear relation between IAP and volume may probably predict the Cabd quite accurately and vice versa. However, larger studies are necessary to safely draw predicting ΔIAP – ΔV (Cabd) diagrams, and determine the optimal ascitic fluid removal to achieve best comforting of the patient and slower fluid reformation.

A Three-Dimensional Human Trunk Model for the Analysis of Respiratory Mechanics

Over the past decade, road safety research and impact biomechanics have strongly stimulated the development of anatomical human numerical models using the finite element (FE) approach. The good accuracy of these models, in terms of geometric definition and mechanical response, should now find new areas of application. We focus here on the use of such a model to investigate its potential when studying respiratory mechanics. The human body FE model used in this study was derived from the RADIOSS HUMOS model. Modifications first concerned the integration and interfacing of a user-controlled respiratory muscular system including intercostal muscles, scalene muscles, the sternocleidomastoid muscle, and the diaphragm and abdominal wall muscles. Volumetric and pressure measurement procedures for the lungs and both the thoracic and abdominal chambers were also implemented. Validation of the respiratory module was assessed by comparing a simulated maximum inspiration maneuver to volunteer studies in the literature. Validation parameters included lung volume changes, rib rotations, diaphragm shape and vertical deflexion, and intra-abdominal pressure variation. The HUMOS model, initially dedicated to road safety research, could be turned into a promising, realistic 3D model of respiration with only minor modifications.

Respiratory variation of intra-abdominal pressure: indirect indicator of abdominal compliance?

To assess if the observed respiratory cycle-related variation in intra-abdominal pressure is reliably quantifiable and a possible indirect indicator of abdominal compliance. Secondary issues were to assess the roles played by respiratory parameters in determining this oscillation and by patients' position in increasing their intra-abdominal pressure. Prospective observational study in a 26-bed medical-surgical intensive care unit. Sixteen consecutive patients admitted to intensive care for at least 24 h, requiring mechanical ventilation and intra-abdominal pressure monitoring. Intra-abdominal pressure was measured with a modified Kron technique; its waveform was recorded and inspiratory and expiratory values were measured during five consecutive respiratory cycles for 5 days, both in the supine and the 30 degrees head-up position. Inspiratory values were significantly higher than expiratory values (p = 0.001) and a correlation was found between their difference and intra-abdominal pressure basal values (p = 0.025). A positive linear relationship was shown between intra-abdominal pressure and the amplitude of its oscillation (r = 0.4), particularly in the subgroup of patients with intra-abdominal hypertension (r = 0.9). Intra-abdominal pressure was lower in patients supine than in the 30 degrees head-up position (p = 0.001). Respiratory cycle-related variations in intra-abdominal pressure were specifically investigated, quantified and shown as linearly increasing with end-expiratory intra-abdominal pressure; this phenomenon could be explained by patients' abdominal compliance status. Supine posture should be an important consideration in specific patients affected by intra-abdominal hypertension.

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.