Intraperitoneal pressure and intra-abdominal pressure: are they the same?

Relationship between intraperitoneal pressure and the development of hernias in peritoneal dialysis: confirmation for the first time of a widely accepted concept

BACKGROUND

Intraperitoneal pressure (IPP) in peritoneal dialysis (PD) is an individual characteristic that can be modified by posture and intraperitoneal volume (IPV). It is considered one of the predisposing factors for complications in the abdominal wall, such as the appearance of hernias. No studies to date have confirmed this. The main aim of this study was to assess the relationship between the development of hernia in incident PD patients and IPP measured at PD onset.

METHODS

A prospective observational study of incident patients in a PD programme between 2010 and 2020. IPP was measured using the Durand's method.

RESULTS

One hundred and twenty-four incident patients on PD, 68% male, mean age 62.1 ± 15.23 years, body mass index (BMI) 27.7 ± 4.82 kg/m2, 44% were diabetic. IPP in supine was 16.6 ± 4.60 cm H2O for a mean IPV of 2047.1 ± 359.19 mL. Hernias were reported in 18.5% of patients during PD follow-up: 57% were inguinal hernias, 33% umbilical, and a further 10% presented in a combined form. PD hernias correlated positively with IPP in supine position (p = 0.037), patient age (p = 0.008), BMI (p = 0.043), a history of prior hernia (0.016), laparoscopic catheter placement (p = 0.026), and technique failure (p = 0.012). In the multivariate analysis, a higher IPP was independently related to the development of hernias (p = 0.028).

CONCLUSIONS

The development of hernias in PD was related to a higher IPP at PD onset, older age, higher BMI, history of prior hernia, catheter placement by laparoscopy, and technique failure.

Feasibility analysis of a novel non-invasive ultrasonographic method for the measurement of intra-abdominal pressure in the intensive care unit

Increased intra-abdominal pressure (IAP) is an important vital sign in critically ill patients and has a negative impact on morbidity and mortality. This study aimed to validate a novel non-invasive ultrasonographic approach to IAP measurement against the gold standard intra-bladder pressure (IBP) method. We conducted a prospective observational study in an adult medical ICU of a university hospital. IAP measurements using ultrasonography by two independent operators, with different experience levels (experienced, IAPUS1; inexperienced, IAPUS2), were compared with the gold standard IBP method performed by a third blinded operator. For the ultrasonographic method, decremental external pressure was applied on the anterior abdominal wall using a bottle filled with decreasing volumes of water. Ultrasonography looked at peritoneal rebound upon brisk withdrawal of the external pressure. The loss of peritoneal rebound was identified as the point where IAP was equal to or above the applied external pressure. Twenty-one patients underwent 74 IAP readings (range 2-15 mmHg). The number of readings per patient was 3.5 ± 2.5, and the abdominal wall thickness was 24.6 ± 13.1 mm. Bland and Altman's analysis showed a bias (0.39 and 0.61 mmHg) and precision (1.38 and 1.51 mmHg) for the comparison of IAPUS1 and IAPUS2 and vs. IBP, respectively with small limits of agreement that were in line with the research guidelines of the Abdominal Compartment Society (WSACS). Our novel ultrasound-based IAP method displayed good correlation and agreement between IAP and IBP at levels up to 15 mmHg and is an excellent solution for quick decision-making in critically ill patients.

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.

A novel in vivo approach to assess strains of the human abdominal wall under known intraabdominal pressure

The study concerns mechanical behaviour of a living human abdominal wall. A better mechanical understanding of a human abdominal wall and recognition of its material properties is required to find mechanically compatible surgical meshes to significantly improve the treatment of ventral hernias. A non-invasive methodology, based on in vivo optical measurements is proposed to determine strains of abdominal wall corresponding to a known intraabdominal pressure. The measurement is performed in the course of a standard procedure of peritoneal dialysis. A dedicated experimental stand is designed for the experiment. The photogrammetric technique is employed to recover the three-dimensional surface geometry of the anterior abdominal wall at the initial and terminal instants of the dialysis. This corresponds to two deformation states, before and after filling the abdominal cavity with dialysis fluid. The study provides information on strain fields of living human abdominal wall. The inquiry is aimed at principal strains and their directions, observed at the level from -10% to 17%. The intraabdominal pressure related to the amount of introduced dialysis fluid measured within the medical procedure covers the range 11-18.5 cmH₂O. The methodology leads to the deformation state of the abdominal wall according to the corresponding loading conditions. Therefore, the study is a step towards an identification of mechanical properties of living human abdominal wall.

Intra-abdominal hypertension in early post-kidney transplantation period is associated with impaired graft function

BACKGROUND

Moderate hyperhydration is often achieved in the early post-kidney transplantation period. Whether this strategy could lead to the development of intra-abdominal hypertension (IAH) has never been assessed so far. We aimed to study the incidence of IAH after kidney transplantation and its association with graft function recovery.

METHODS

We conducted a prospective monocentric study among patients undergoing kidney transplantation at the University Hospital of Reims between May 2017 and April 2019. Intravesical pressure (IVP) was monitored every 8 h from Day 0 to 3.

RESULTS

A total of 107 patients were enrolled. Among 55 patients included in the analysis, 74.5% developed IAH. Body mass index >25 kg/m2 was associated with IAH development {odds ratio [OR] 10.4 [95% confidence interval (CI) 2.0-52.9]; P = 0.005}. A previous history of peritoneal dialysis was protective [OR 0.06 (95% CI 0.01-0.3); P = 0.001]. IAH Grades III and IV occurred in 30.9% of patients and correlated with higher Day 3 creatininaemia (419.6 ± 258.5 versus 232.5 ± 189.4 μmol/L; P = 0.02), higher delayed graft function incidence (41.2 versus 7.9%; P = 0.04), lower Kirchner index measured using scintigraphy (0.47 ± 0.09 versus 0.64 ± 0.09; P = 0.0005) and decreased Day 30 estimated glomerular filtration rate (35.8 ± 18.8 versus 52.5 ± 21.3, P = 0.05). IAH patients had higher fluid balance (P = 0.02). Evolution of IVP correlated with weight gain (P < 0.01) and central venous pressure (P < 0.001).

CONCLUSIONS

IAH is frequent after kidney transplantation and IAH Grades III and IV are independently associated with impaired graft function. These results question current haemodynamic objectives and raise for the first time interest in intra-abdominal pressure monitoring in these patients.

CLINICAL TRIAL NOTATION

ClinicalTrials.gov identifier: NCT03478176.

Intraperitoneal pressure: Stability over time and validation of Durand's measurement method

Intraperitoneal pressure (IPP) is gaining consideration as a relevant parameter of peritoneal dialysis (PD) in adults, although many of its aspects are still pending clarification. We address here its stability over time and the validity of the usual method of clinical measurement, as proposed by Durand in 1992 but never specifically validated. We performed this validation by comparing Durand's method and direct measurements with a central venous pressure system. We performed a total of 250 measurement pairs in 50 patients with different intraperitoneal volumes plus in-vitro measurements with a simulated peritoneum. Absolute differences between the two systems in vivo were 0.87 ± 0.91 cmH₂O (range 0-5 cmH₂O); only 6.4% of them were ≥3 cmH₂O. In vitro results for both methods were identical. We also compared IPP measurements in the same patient separated by 1-4 h (514 measurement pairs in 136 patients), 1 week (92 pairs in 92 patients), and 2 years (34 pairs in 17 patients). Net differences of measurements separated by hours or 1 week were close to 0 cmH₂O, with oscillations of 1.5 cmH₂O in hours and 2.3 cmH₂O in 1 week. IPP measured 2 years apart presented a net decrease of 2.5 ± 4.9 cmH₂O, without correlation with body mass index changes or any other usual parameter of PD. In hours, 7% of IPP differences were >3 cmH₂O, 22% in 1 week, and 50% in 2 years. In conclusion, Durand's method is precise enough to measure IPP in peritoneal dialysis. This parameter is not stable over long timescales, so it is necessary to use recent measurements.

Supine equilibration of extracellular fluid in peritoneal dialysis varies with intra-abdominal pressure

BACKGROUND

Increased intra-abdominal pressure (PIA) leads to venous congestion in splanchnic and adjoining circulations. The aim is to examine whether PIA in peritoneal dialysis (PD) affects the mobilization of extracellular fluid from the lower body in supine body position.

METHODS

Patients were studied during a regular peritoneal equilibration test (PET) in supine body position using multifrequency bioimpedance analysis to determine extracellular resistance and absolute volume overload (AVO) in wrist-to-ankle (W2A) as well as in ankle-to-ankle (A2A) configurations. Measurements were taken at baseline (T0) after draining the peritoneal cavity, at T1 shortly after filling with 2 L of standard dialysate, and at T2 before taking the 2 h PET samples. PIA was measured from the column height in the PD catheter. Extracellular resistance in the lower extremities (RL) was taken as half of the A2A resistance.

RESULTS

Eighteen patients (56 ± 15 years, 76 ± 21 kg, body mass index (BMI) 26.4 ± 7 kg/m², 13 men) were studied. After having assumed a supine body position for the duration of 17, 77, and 155 min, AVO continuously decreased from 1.6 ± 1.3 (T0) to 1.2 ± 1.5 (T1) and 1.0 ± 1.4 L (T2). RL significantly increased from 238 ± 57 (T0) to 254 ± 62 (T1) and 264 ± 67 Ohm (T2). This increase was negatively correlated to BMI and PIA measured at any time point, but not to net ultrafiltration volume.

CONCLUSIONS

Orthostatic fluid shifts from the lower limbs may take up to 2 h in supine PD patients, especially with high BMI and PIA because of venous congestion in splanchnic and adjoining circulations.

Clinical relevance of marginal factors on ultrafiltration in peritoneal dialysis

BACKGROUND

Ultrafiltration (UF) in peritoneal dialysis (PD) is mainly driven by the osmotic gradient and peritoneal permeability, but other factors-such as intraperitoneal pressure (IPP)-also have an influence.

METHODS

To assess the clinical relevance of these marginal factors, we studied 41 unselected PD patients undergoing two consecutive 2 h, 2.27% glucose exchanges, first with 2.5 L and then with 1.5 L.

RESULTS

IPP, higher in the 2.5 L exchange, had a wide interpatient range, was higher in obese and polycystic patients and their increase with infusion volume was higher for women regardless of body size. UF with 2.5 L correlated inversely with IPP and was higher for patients with polycystosis or hernias, while for 1.5 L we found no significant correlations. The effluent had higher glucose and osmolarity in the 2.5 L exchange than in the 1.5 L one, similar for both sexes. In spite of this stronger osmotic gradient, only 21 patients had more UF in the 2.5 L exchange, with differences up to 240 mL. The other 20 patients had more UF in the 1.5 L exchange, with stronger differences (up to 800 mL, and more than 240 mL for 9 patients). The second group, with similar effluent osmolarity and peritoneal equilibration test (PET) parameters than the first, has higher IPP and preponderance of men. The sex influence is so intense that men decreased average UF with 2.5 L with respect to 1.5 L, while women increased it.

CONCLUSIONS

With 2.27% glucose, sex and IPP-modulated by obesity, polycystosis, hernias, and intraperitoneal volume-significantly affect UF in clinical settings and might be useful for its management.

Clinical Relevance of Intraperitoneal Pressure in Peritoneal Dialysis Patients

Introduction

Intraperitoneal pressure (IPP) in peritoneal dialysis (PD) increases in sitting and upright positions and is related to some individual characteristics. Adverse effects can appear with IPP > 20 cm H2O. Few studies about peritoneal transport or abdominal wall problems have directly measured IPP. We measured IPP in our prevalent PD patients to identify the clinical factors related to its variability and its possible association with peritoneal transport and abdominal wall complications.

Methods

We performed a retrospective, observational study of our stable PD patients. Intraperitoneal pressure was measured using the Durand's method in supine, sitting, and upright position.

Results

Forty-nine patients were included, 70% males, mean age 61.1 ± 15 years, body mass index (BMI) 27.9 ± 5.2 kg/m2. The mean of supine IPP was 18.0 ± 4.4 cm H2O. Intraperitoneal pressure in sitting and upright positions were similar and higher than in supine. Supine IPP showed a positive correlation with BMI ( p < 0.0005) and comorbidity ( p < 0.05). A multivariate linear regression analysis showed that BMI and comorbidity ( p < 0.005) had a positive correlation with IPP; time on PD and daily total ultrafiltration (UF) (p < 0.005) showed a negative correlation. Patients with an IPP ≥ 20 cm H2O had more hernias (35% vs 17%) and leakages (21% vs 8%) without statistical significance.

Conclusion

Our supine IPPs were higher than others published in adults. Intraperitoneal pressure has an individual value associated with body size. Greater IPP was correlated with lower daily total UF and more hernias and leakages. The measurement of IPP is a simple technique and can help with PD prescription, especially in obese patients.

Abdominal compartment syndrome in severe acute pancreatitis treated with percutaneous catheter drainage

Acute pancreatitis is one of the main causes of intra-abdominal hypertension (IAH). IAH contributes to multiple physiologic alterations and leads to the development of abdominal compartment syndrome (ACS) that induces multiorgan failure. We report a case of ACS in a patient with severe acute pancreatitis. A 44-year-old man who was admitted in a drunk state was found to have severe acute pancreatitis. During management with fluid resuscitation in an intensive care unit, drowsy mentality, respiratory acidosis, shock requiring inotropes, and oliguria developed in the patient, with his abdomen tensely distended. With a presumptive diagnosis of ACS, abdominal decompression through percutaneous catheter drainage was performed immediately. The intraperitoneal pressure measured with a drainage catheter was 31 mm Hg. After abdominal decompression, the multiorgan failure was reversed. We present a case of ACS managed with percutaneous catheter decompression.

Differential pressure in shunt therapy: investigation of position-dependent intraperitoneal pressure in a porcine model

OBJECT

The differential pressure between the intracranial and intraperitoneal cavities is essential for ventriculoperitoneal shunting. A determination of the pressure in both cavities is decisive for selecting the appropriate valve type and opening pressure. The intraperitoneal pressure (IPP)-in contrast to the intracranial pressure-still remains controversial with regard to its normal level and position dependency.

METHODS

The authors used 6 female pigs for the experiments. Two transdermal telemetric pressure sensors (cranial and caudal) were implanted intraperitoneally with a craniocaudal distance of 30 cm. Direct IPP measurements were supplemented with noninvasive IPP measurements (intragastral and intravesical). The IPP was measured with the pigs in the supine (0°), 30°, 60°, and vertical (90°) body positions. After the pigs were euthanized, CT was used to determine the intraperitoneal probe position.

RESULTS

With pigs in the supine position, the mean (± SD) IPP was 10.0 ± 3.5 cm H2O in a mean vertical distance of 4.5 ± 2.8 cm to the highest level of the peritoneum. The difference between the mean IPP of the cranially and the caudally implanted probes (Δ IPP) increased according to position, from 5.5 cm H2O in the 0° position to 11.5 cm H2O in the 30° position, 18.3 cm H2O in the 60° position, and 25.6 cm H2O in the vertical body position. The vertical distance between the probe tips (cranially implanted over caudally implanted) increased 3.4, 11.2, 19.3, and 22.3 cm for each of the 4 body positions, respectively. The mean difference between the Δ IPP and the vertical distance between both probe tips over all body positions was 1.7 cm H2O.

CONCLUSIONS

The IPP is subject to the position-dependent hydrostatic force. Normal IPP is able to reduce the differential pressure in patients with ventriculoperitoneal shunts.

Renal consequences of intraabdominal hypertension in a porcine model. Search for the choice indirect technique for intraabdominal pressure measurement

OBJECTIVE

To study the effects on the renal system in a porcine model of intraabdominal hypertension, and to determine the indirect technique of choice for determination of the intraabdominal pressure.

MATERIAL AND METHODS

30 pigs were used divided in two groups according with increased intraabdominal pressure values (20 mmHg and 30 mmHg). In both groups pressures were registered 8 times, summing up to 3 hours, with a CO₂ insufflator. Three different measures of the intraabdominal pressure were taken: a direct transperitoneal measure, using a catheter of Jackson-Pratt connected to a pressure transducer, and two indirect measures, a transvesical by means of a Foley to manometer system, and a transgastric by introducing in the stomach a catheter connected to a pressure monitor with electronic hardware. Mean arterial pressure was calculated, along with the cardiac index, production of urine and serum creatinine.

RESULTS

There was a greater correlation between the transvesical and the transperitoneal intraabdominal pressures (R(2)=0,95). Average transgastric intraabdominal pressure was inferior to the transperitoneal indicator in all taken measurements. The average arterial pressure descended in both groups, with earlier significant differences observed at 30 mmHg (p<0,020). Urine production was lower at 30 mmHg compared with the 20 mmHg group (9,63 ± 1,57 versus 3.26 ml ± 1,73). Serum creatinine increased in both groups being pathological at 30 mmHg after 1h 20 min, with existing differences between early pressures (p<0,027).

CONCLUSIONS

This study revealed marked renal affectation with higher severity at 30 mmHg pressures. The transvesical technique showed a greater correlation with the direct measurement technique used, defining this as the method of choice for determination of intraabdominal pressure.