The neglected role of abdominal compliance in organ-organ interactions

The abdominal compliance index and postoperative pain after laparoscopic gynecologic surgery: a preliminary observational cohort study

Background/aim

In gynecology, laparoscopic surgery has the advantages of reduced scarring, less postoperative pain, faster recovery, and lower risk of complications. Despite these advantages, shoulder pain still remains a major concern, affecting up to 90% of patients undergoing gynecologic laparoscopic surgery. Use of the abdominal compliance index (ACI) may offer the benefit of increased space for safer surgery and may prevent the drawback of high insufflation pressures. The aim of this study was to investigate the relationship between shoulder pain, abdominal pain, and analgesic use with the recently advised ACI, a surrogate index of abdominal expansion in patients undergoing gynecologic laparoscopic surgery.

Materials and methods

Thirty-one patients with American Society of Anesthesiologists scores of 1-3 who underwent elective gynecologic laparoscopic surgery were included. The insufflation pressure was set to 12 mmHg. ACI, defined as insufflated intraabdominal volume (L) per body surface area (m2), was used to estimate the relationship between abdominal compliance and postoperative pain.

Results

The 31 patients were separated into two groups based on median ACI level (range 1.37-2.73 L/m2), with those having values of 2.16 L/m2 or lower as group 1 and those with higher values as group 2. Abdominal visual analogue scale (VAS) scores at 30 min postoperative were significantly higher in group 2 than in group 1 (p < 0.001). Shoulder pain VAS scores at 24 h and 36 h postoperative were also significantly higher in group 2 than in group 1 (p = 0.021 and p = 0.002, respectively). The total amount of analgesic infusion and additional analgesic requirements were lower in group 1 than in group 2 (p = 0.049 and p = 0.001, respectively). ACI did not differ with patient demographic characteristics or history of abdominal/laparoscopic surgery, parity, abdominal drainage, and pneumoperitoneum time.

Conclusion

ACI, a surrogate index of abdominal expansion capacity, may be used to guide individualization of insufflation pressures by identifying female patients under risk of higher postoperative pain.

International cross-sectional survey on current and updated definitions of intra-abdominal hypertension and abdominal compartment syndrome

BACKGROUND

The Abdominal Compartment Society (WSACS) established consensus definitions and recommendations for the management of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) in 2006, and they were last updated in 2013. The WSACS conducted an international survey between 2022 and 2023 to seek the agreement of healthcare practitioners (HCPs) worldwide on current and new candidate statements that may be used for future guidelines.

METHODS

A self-administered, online cross-sectional survey was conducted under the auspices of the WSACS to assess the level of agreement among HCPs over current and new candidate statements. The survey, distributed electronically worldwide, collected agreement or disagreement with statements on the measurement of intra-abdominal pressure (IAP), pathophysiology, definitions, and management of IAH/ACS. Statistical analysis assessed agreement levels, expressed in percentages, on statements among respondents, and comparisons between groups were performed according to the respondent's education status, base specialty, duration of work experience, role (intensivist vs non-intensivist) and involvement in previous guidelines. Agreement was considered to be reached when 80% or more of the respondents agreed with a particular statement.

RESULTS

A total of 1042 respondents from 102 countries, predominantly physicians (73%), of whom 48% were intensivists, participated. Only 59% of HCPs were aware of the 2013 WSACS guidelines, and 41% incorporated them into practice. Despite agreement in most statements, significant variability existed. Notably, agreement was not reached on four new candidate statements: "normal intra-abdominal pressure (IAP) is 10 mmHg in critically ill adults" (77%), "clinical assessment and estimation of IAP is inaccurate" (65.2%), "intragastric can be an alternative to the intravesical route for IAP measurement" (70.4%), and "measurement of IAP should be repeated in the resting position after measurement in a supine position" (71.9%). The survey elucidated nuances in clinical practice and highlighted areas for further education and standardization.

CONCLUSION

More than ten years after the last published guidelines, this worldwide cross-sectional survey collected feedback and evaluated the level of agreement with current recommendations and new candidate statements. This will inform the consensus process for future guideline development.

Evaluation of residual dentin thickness using quantitative light-induced fluorescence technology

This study aimed to determine whether a correlation exists between residual dentin thickness and quantitative light-induced fluorescence (QLF) values and, if so, to analyze its tendencies. Forty extracted sound human molars were assigned to filled and unfilled groups. The teeth were submerged in a mold with clear acrylic resin. Red utility wax was inserted into the pulp chamber space in the filled group to simulate vital pulp. The specimen was sectioned longitudinally to observe the inside of the pulp space. The samples were cut horizontally from the highest point of the pulp space 2 mm apart. QLF images were then taken of 2 mm, 1 mm, and 0.5 mm samples using the QLF-D Biluminator™ 2 + system. Three operators independently evaluated the QLF images, and the statistical analysis was conducted using one-way analysis of variance, Pearson correlation coefficients, and intraclass correlation coefficients. In the filled group, the mean ΔF values for residual dentin thicknesses of 2 mm, 1 mm, and 0.5 mm were - 3.22, - 7.84, and  - 11.52, respectively. In the unfilled group, the mean ΔF values were 0, - 6.90, and - 10.14, respectively. A positive correlation was found between residual dentin thickness and ΔF values (P < 0.05). The intraclass correlation coefficients for observations made by the three operators for the filled and unfilled groups were 0.831 and 0.917, respectively (P < 0.05). In conclusion, residual dentin thickness and ΔF values were significantly correlated and had a highly positive correlation regardless of the QLF device operator.

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

BACKGROUND

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.

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

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

BACKGROUND

Monitoring 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.

METHOD

In 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.

RESULTS

The 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.

CONCLUSION

The 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.

The development, feasibility and credibility of intra-abdominal pressure measurement techniques: A scoping review

AIM

To provide a comprehensive overview on emerging direct and alternative methods for intra-abdominal pressure (IAP) measurement techniques.

METHODS

This was a scoping review study following Arksey and Malley's framework. The PubMed, EMBASE, Web of Science, EBSCO, Scopus and ProQuest databases were searched, and we only considered studies published from 2000 as we have extended the data from two previous reviews. Original studies that reported on the development, feasibility and credibility of IAP measurement techniques were included.

RESULTS

Forty-two of 9954 screened articles were included. IAP measurement techniques include three major categories: direct, indirect and less invasive measurement techniques. Agreement analyses were performed in most studies, and some explored the safety, time expenditure and reproducibility of IAP measurement techniques.

CONCLUSIONS

Clinical data assessing the validation of new IAP measurement techniques or the reliability of established measurement techniques remain lacking. Considering the cost and invasiveness, direct measurement is not recommended as a routine method for IAP measurement and should be preserved for critically ill patients where standard techniques are contraindicated or could be inaccurate. The measurement accuracy, reliability and sensitivity of the transrectal and transfemoral vein methods remain insufficient and cannot be recommended as surrogate IAP measures. Transvesical measurement is the most widely used method, which is the potentially most easy applicable technique and can be used as a reliable method for continuous and intermittent IAP measurement. Wireless transvaginal method facilitates the quantitative IAP measurement during exercise and activity, which laying the foundations for monitoring IAP outside of the clinic environment, but the accuracy of this technique in measuring absolute IAP cannot be determined at present. Less invasive technology will become a new trend to measure IAP and has substantial potential to replace traditional IAP measurement technologies, but further validation and standardization are still needed. Medical professionals should choose appropriate measurement tools based on the advantages and disadvantages of each IAP technique in combination with assessing specific clinical situations.

Crosstalk Between the Nervous System and Systemic Organs in Acute Brain Injury

Organ crosstalk is a complex biological communication between distal organs mediated via cellular, soluble, and neurohormonal actions, based on a two-way pathway. The communication between the central nervous system and peripheral organs involves nerves, endocrine, and immunity systems as well as the emotional and cognitive centers of the brain. Particularly, acute brain injury is complicated by neuroinflammation and neurodegeneration causing multiorgan inflammation, microbial dysbiosis, gastrointestinal dysfunction and dysmotility, liver dysfunction, acute kidney injury, and cardiac dysfunction. Organ crosstalk has become increasingly popular, although the information is still limited. The present narrative review provides an update on the crosstalk between the nervous system and systemic organs after acute brain injury. Future research might help to target this pathophysiological process, preventing the progression toward multiorgan dysfunction in critically ill patients with brain injury.

Abdominal compartment syndrome in critically ill patients

Intra-abdominal hypertension can have severe consequences, including abdominal compartment syndrome, which can contribute to multi-organ failure. An increase in intra-abdominal hypertension is influenced by factors such as diminished abdominal wall compliance, increased intraluminal content, and certain systemic conditions. Regular measurement of intra-abdominal pressure is essential, and particular attention must be paid to patient positioning. Nonsurgical treatments, such as decompression of intraluminal content using a nasogastric tube, percutaneous drainage, and fluid balance optimization, play crucial roles. Additionally, point-of-care ultrasonography aids in the diagnosis and treatment of intra-abdominal hypertension. Emphasizing the importance of regular measurements, timely decompressive laparotomy is a definitive, but complex, treatment option. Balancing the urgency of surgical intervention against potential postoperative complications is challenging.

Surgical decompression for the management of abdominal compartment syndrome with severe acute pancreatitis: A narrative review

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) play a pivotal role in the pathophysiology of severe acute pancreatitis (SAP) and contribute to new-onset and persistent organ failure. The optimal management of ACS involves a multi-disciplinary approach, from its early recognition to measures aiming at an urgent reduction of intra-abdominal pressure (IAP). A targeted literature search from January 1, 2000, to November 30, 2022, revealed 20 studies and data was analyzed on the type and country of the study, patient demographics, IAP, type and timing of surgical procedure performed, post-operative wound management, and outcomes of patients with ACS. There was no randomized controlled trial published on the topic. Decompressive laparotomy is effective in rapidly reducing IAP (standardized mean difference = 2.68, 95% confidence interval: 1.19-1.47, P < 0.001; 4 studies). The morbidity and complications of an open abdomen after decompressive laparotomy should be weighed against the inadequately treated but, potentially lethal ACS. Disease-specific patient selection and the role of less-invasive decompressive measures, like subcutaneous linea alba fasciotomy or component separation techniques, is lacking in the 2013 consensus management guidelines by the Abdominal Compartment Society on IAH and ACS. This narrative review focuses on the current evidence regarding surgical decompression techniques for managing ACS in patients with SAP. However, there is a lack of high-quality evidence on patient selection, timing, and modality of surgical decompression. Large prospective trials are needed to identify triggers and effective and safe surgical decompression methods in SAP patients with ACS.

Sánchez-Margallo F, Eugenia Candanosa-Aranda I, Poelaert J, Castellanos G, L. N. G. Malbrain M. The pathophysiological impact of intra-abdominal hypertension in pigs

BACKGROUND

Intra-abdominal hypertension and abdominal compartment syndrome are common with clinically significant consequences. We investigated the pathophysiological effects of raised IAP as part of a more extensive exploratory animal study. The study design included both pneumoperitoneum and mechanical intestinal obstruction models.

METHODS

Forty-nine female swine were divided into six groups: a control group (Cr; n = 5), three pneumoperitoneum groups with IAPs of 20mmHg (Pn20; n = 10), 30mmHg (Pn30; n = 10), 40mmHg (Pn40; n = 10), and two mechanical intestinal occlusion groups with IAPs of 20mmHg (MIO20; n = 9) and 30mmHg (MIO30; n = 5).

RESULTS

There were significant changes (p<0.05) noted in all organ systems, most notably systolic blood pressure (SBP) (p<0.001), cardiac index (CI) (p = 0.003), stroke volume index (SVI) (p<0.001), mean pulmonary airway pressure (MPP) (p<0.001), compliance (p<0.001), pO2 (p = 0.003), bicarbonate (p = 0.041), hemoglobin (p = 0.012), lipase (p = 0.041), total bilirubin (p = 0.041), gastric pH (p<0.001), calculated glomerular filtration rate (GFR) (p<0.001), and urine output (p<0.001). SVV increased progressively as the IAP increased with no obvious changes in intravascular volume status. There were no significant differences between the models regarding their impact on cardiovascular, respiratory, renal and gastrointestinal systems. However, significant differences were noted between the two models at 30mmHg, with MIO30 showing worse metabolic and hematological parameters, and Pn30 and Pn40 showing a more rapid rise in creatinine.

CONCLUSIONS

This study identified and quantified the impact of intra-abdominal hypertension at different pressures on several organ systems and highlighted the significance of even short-lived elevations. Two models of intra-abdominal pressure were used, with a mechanical obstruction model showing more rapid changes in metabolic and haematological changes. These may represent different underlying cellular and vascular pathophysiological processes, but this remains unclear.

Avoiding High Pressure Abdominal Closure of Congenital Abdominal Wall Defects-One Step Further to Improve Outcomes

The main goal of surgical treatment for gastroschisis and omphalocele is the reduction of viscera in the abdominal cavity and closure of the abdomen, but the challenge is to succeed without the detrimental effects of increased intraabdominal pressure. In this regard, we performed a retrospective study for all patients admitted for gastroschisis and omphalocele to the Neonatal Intensive Care Unit of 'Marie Sklodowska Curie' Emergency Clinical Hospital for Children, from January 2011 until June 2021. Our aim was to highlight the presence of postoperative abdominal compartment syndrome. We observed that six out of forty-seven patients developed clinical signs of abdominal compartment syndrome, five associated with primary closure and one with staged closure with a polyvinyl chloride patch. Following the results, we decided to implement the trans-bladder measurement of intraabdominal pressure to avoid closing the abdomen at pressures higher than 10 mmHg in order to prevent the development of abdominal compartment syndrome. We consider that there is still place for the improvement of congenital abdominal wall defects management and that the measurement of intraabdominal pressure might help us reach our goal.

Effects of intra-abdominal hypertension on maternal-fetal outcomes in term pregnant women: A systematic review

OBJECTIVE

To carry out a systematic review to assess the effects of intra-abdominal hypertension on maternal-fetal outcomes.

METHODS

The search was carried out between 28th June to 4th July 2022 on the Biblioteca Virtual em Saúde, Pubmed, Embase, Web of Science, and Cochrane databases. The study was registered in PROSPERO (CRD42020206526). The systematic review was performed according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. To assess the methodological quality and control the risk of bias, New Castle was used.

RESULTS

A total of 6203 articles were found. Of these, 5 met the selection criteria for a full reading. The selected studies included a total of 271 pregnant women, of which 242 underwent elective cesarean section and measurement of intra-abdominal pressure via a bladder catheter. In both pregnant women groups, the lowest intra-abdominal pressure values were found in the supine position with left lateral tilt. Prepartum values in normotensive women with singleton pregnancy (7.3±1.3 to 14.1 ± 1 mmHg) were lower than in gestational hypertensive disorders (12.0±3.3 to 18.3±2.6 mmHg). In postpartum, the values decreased in both groups but were even lower in normotensive women (3.7±0.8 to 9.9 ± 2.6 mmHg vs 8.5 ± 3.6 to 13.6 ± 3.3 mmHg). The same was true for twin pregnancies. The Sequential Organ Failure Assessment index ranged from 0.6 (0.5) to 0.9 (0.7) in both groups of pregnant women. The placental malondialdehyde levels were statistically (p < 0.05) higher in pregnant women with pre-eclampsia (2.52±1.05) than normotensive (1.42±0.54).

CONCLUSIONS

Prepartum intra-abdominal pressure values in normotensive women were close or equal to intra-abdominal hypertension and compatible with gestational hypertensive disorders even in the postpartum period. IAP values were consistently lower in supine position with lateral tilt in both groups. Significant correlations were found between prematurity, low birth weight, pregnant women with hypertensive disorders, and increased intra-abdominal pressure. However, there was no significant association of dysfunction in any system in the relationship between intra-abdominal pressure and Sequential Organ Failure Assessment. Despite the higher malondialdehyde values in pregnant women with pre-eclampsia, the findings were inconclusive. Given the observed data on maternal and fetal outcomes, it would be recommended that intra-abdominal pressure measurements be standardized and used as a diagnostic tool during pregnancy.

TRIAL REGISTRATION

PROSPERO registration: October 9th, 2020, CRD42020206526.

The spine intra-abdominal pressure (SIAP) trial. A prospective, observational, single arm, monocenter study looking at the evolutions of the IAP prior, during and after spine surgery

BACKGROUND AND AIMS

Both anaesthesiologists and spine surgeons consider the intra-abdominal pressure (IAP) as an important peri-operative factor affected by patient positioning. We assessed the change in IAP caused by using a thoraco pelvic support (inflatable prone support, IPS) with the subject under general anesthesia. The IAP was measured before, during and immediately after surgery.

METHODS

The Spine Intra-Abdominal Pressure study (SIAP trial) is a prospective, single-arm, monocenter, observational study looking at changes in IAP prior, during and after spine surgery. The objective is to assess the change in IAP, measured via an indwelling urinary catheter, using the inflatable prone support (IPS) device during prone positioning of patients in spinal surgery.

RESULTS

Forty (40) subjects requiring elective lumbar spine surgery in prone position were enrolled after providing informed consent. The inflation of the IPS results in a significant decrease of IAP (from a median of 9.2 mmHg to 6.46 mmHg (p < 0.001)) in patients undergoing spine surgery in prone position. This decrease in IAP was maintained throughout the procedure despite the discontinuation of muscle relaxants. No serious adverse events or unexpected adverse events occurred.

CONCLUSION

The use of the thoraco-pelvic support IPS device was able to significantly lower the IAP during spine surgery.

Intra-abdominal hypertension in cardiac surgery patients: a multicenter observational sub-study of the Accuryn registry

Intra-abdominal hypertension (IAH) is frequently present in the critically ill and is associated with increased morbidity and mortality. Conventionally, intermittent 'spot-check' manual measurements of bladder pressure in those perceived as high risk are used as surrogates for intra-abdominal pressure (IAP). True patterns of IAH remain unknown. We explored the incidence of IAH in cardiac surgery patients and describe the intra-and postoperative course of IAP using a novel, high frequency, automated bladder pressure measurement system. Sub-analysis of a prospective, multicenter, observational study (NCT04669548) conducted in three large academic medical centers. Continuous urinary output (CUO) and IAP measurements were observed using the Accuryn Monitoring System (Potrero Medical, Hayward, CA). Data collected included demographics, hemodynamic support, and high-frequency IAP and CUO. One Hundred Thirty-Seven cardiac surgery patients were analyzed intraoperatively and followed 48 h postoperatively in the intensive care unit. Median age was 66.4 [58.3, 72.0] years, and 61% were men. Median Foley catheter dwell time was 56.0 [46.8, 77.5] hours, and median baseline IAP was 6.3 [4.0, 8.1] mmHg. 93% (128/137) of patients were in IAH grade I, 82% (113/137) in grade II, 39% (53/137) in grade III, and 5% (7/137) in grade IV for at least 12 cumulative hours. For maximum consecutive duration of IAH, 84% (115/137) of patients spent at least 12 h in grade I, 62% (85/137) in grade II, 18% (25/137) in grade III, and 2% (3/137) in grade IV IAH. During the first 48 h after cardiac surgery, IAH is common and persistent. Improved and automated monitoring of IAP will increase the detection of IAH-which normally would remain undetected using traditional intermittent monitoring methods.

Abdominal Compartment Syndrome in Acute Pancreatitis: A Narrative Review

Abdominal compartment syndrome (ACS) represents a severe complication of acute pancreatitis (AP), resulting from an acute and sustained increase in abdominal pressure >20 mmHg, in association with new organ dysfunction. The harmful effect of high intra-abdominal pressure on regional and global perfusion results in significant multiple organ failure and is associated with increased morbidity and mortality. There are several deleterious consequences of elevated intra-abdominal pressure on end-organ function, including respiratory, cardiovascular, gastrointestinal, neurologic, and renal effects. It is estimated that about 15% of patients with severe AP develop intra-abdominal hypertension or ACS, with a mortality rate around 50%. The treatment of abdominal compartment syndrome in acute pancreatitis begins with medical intervention and percutaneous drainage, where possible. Abdominal compartment syndrome unresponsive to conservatory treatment requires immediate surgical decompression, along with vacuum-assisted closure therapy techniques, followed by early abdominal fascia closure.

Physicians' Knowledge of Abdominal Compartment Syndrome and Intra-Abdominal Hypertension in Saudi Arabia: An Online Cross-Sectional Survey Study

Objective

To determine physicians' knowledge of abdominal compartment syndrome and intra-abdominal hypertension in Saudi Arabia.

Methods

A cross-sectional online survey study was conducted on physicians in Saudi Arabia between March and August 2022. A previously developed questionnaire was adapted and used in this study. The survey instrument investigated the knowledge and management of intra-abdominal hypertension and abdominal compartment syndrome among physicians. Logistic regression was used to identify predictors of being knowledgeable about abdominal compartment syndrome and intra-abdominal hypertension.

Results

A total of 266 physicians participated in this study. Around one-fifth (21.8%) the study participants were ICU physicians and 25.0% reported that they practice internal medicine. Intra-abdominal hypertension (IAH) and the impact of increased intra-abdominal pressure (IAP) on organ function were terms that the majority of research participants (70.3%) reported they were familiar with. A similar percentage (73.7%) reported that they are familiar with abdominal compartment syndrome (ACS). Around 43.0% of the study participants reported that they do not know how to measure IAP. The most frequently reported (13.5%) intervention in the treatment of IAH and ACS was the use of inotropes or vasopressors. The study participants showed a weak level of knowledge of ACS and IAH with a median score of 3.00 (IQR: 5.00-2.00), which represents 27.3% of the maximum attainable score. Physicians working at hospitals with 20-50 ICU beds were 41.0% (odds ratio: 0.59 (CI: 0.37-0.96)) less likely to be knowledgeable about intra-abdominal hypertension and abdominal compartment syndrome (p≤0.05).

Conclusion

Physicians demonstrated a low level of IAP and ACS knowledge. To increase the safety of medical practices and enhance clinical outcomes for patients, awareness should be raised about the proper diagnosis and management of IAP and ACS. Future research should focus on developing effective educational strategies to improve physicians' understanding of IAP and ACS.

A novel method for monitoring abdominal compliance to optimize insufflation pressure during laparoscopy

BACKGROUND

Abdominal compliance describes the ease of expansion of the abdominal cavity. Several studies highlighted the importance of monitoring abdominal compliance (Cab) during the creation of laparoscopic workspace to individualize the insufflation pressure. The lack of validated clinical monitoring tools for abdominal compliance prevents accurate tailoring of insufflation pressure. Oscillometry, also known as the forced oscillation technique (FOT), is currently used to measure respiratory mechanics and has the potential to be adapted for monitoring abdominal compliance. This study aimed to define, develop and evaluate a novel approach which can monitor abdominal compliance during laparoscopy using endoscopic oscillometry.

MATERIALS AND METHODS

Endoscopic oscillometry was evaluated in a porcine model for laparoscopy. A custom-built insufflator was developed for applying an oscillatory pressure signal superimposed onto a mean intra-abdominal pressure. This insufflator was used to measure the abdominal compliance at insufflation pressures ranging from 5 to 20 hPa (3.75 to 15 mmHg). The measurements were compared to the static abdominal compliance, which was measured simultaneously with computed tomography imaging.

RESULTS

Endoscopic oscillometry recordings and CT images were obtained in 10 subjects, resulting in 76 measurement pairs for analysis. The measured dynamic Cab ranged between 0.0216 and 0.261 L/hPa while the static Cab based on the CT imaging ranged between 0.0318 and 0.364 L/hPa. The correlation showed a polynomial relation and the adjusted R-squared was 97.1%.

CONCLUSIONS

Endoscopic oscillometry can be used to monitor changes in abdominal compliance during laparoscopic surgery, which was demonstrated in this study with a comparison with CT imaging in a porcine laparoscopy model. Use of this technology to personalize the insufflation pressure could reduce the risk of applying excessive pressure and limit the drawbacks of insufflation.

Feasibility of open abdomen surgery treatment for near fatal necrotizing enterocolitis in preterm infants

INTRODUCTION

Necrotizing Enterocolitis (NEC) remained a dramatic complication leading to death or neonatal morbidities in preterms. For some, Intra-Abdominal Hypertension (IAH) and Abdominal Compartment Syndrome worsened the multi-organ failure. An open abdomen surgery could be an alternative to conventional surgical treatment to move beyond this stage.

OBJECTIVES

To retrospectively describe the clinical course, pre- and post-operative features of preterms suffering from severe NEC with IAH treated by open abdomen surgery and referred to our center from October 2007 to September 2019. Our secondary objective is to identify various risk factors for mortality in this population.

METHODS

Data on neonatal, clinical, biological, pre and post-operative features and outcome were collected. Univariate analyses were performed to compare their pre and post-operative features stratifying on outcome.

RESULTS

Among 29 included patients, 14 (48%) survived to discharge without short bowel syndrome. Death was associated with an earlier postnatal age at NEC (16.3 ± 9.1 versus 31.3 ± 25.9 days; p = 0.004) and followed a withdrawal of treatment in 60% of cases. Surgery was associated with a significant improvement of respiratory and hemodynamic features (decrease of mean ventilator pressure from 13.1 ± 5.4 to 11.3 ± 4.0 cmH2O, p < 0.001), oxygen requirement (mean FiO2 decreased from 65.0% ± 31.2 to 49.0% ± 24.6, p < 0.001) and inotropic score (from 38.6 ± 70.1 to 29.9 ± 64.3, p < 0.001). In the survival group, pre and post-operative findings exhibited a significant increase of serum lactate concentrations from 2.7 ± 1.6 to 11.0 ± 20.3 mmol/L (p = 0.02) but a similar pH.

CONCLUSION

Open abdomen surgery could be considered to rescue preterms with near fatal NEC. IAH and Abdominal Compartment Syndrome in these preterms should be investigated through further studies.

LEVEL OF EVIDENCE

Level III.

Development and evaluation of a numerical spine model comprising intra-abdominal pressure for use in assessing physiological changes on abdominal compliance and spinal stability

BACKGROUND

Abdominal compliance is the "measure of ease of abdominal expansion" and determines whether a patient can withstand high intra-abdominal pressures. Thus, high compliance indicates that the abdomen can expand relatively freely, while low compliance restricts abdominal expansion. The global objective of the present work is to evaluate the effect of physiological changes on abdominal compliance using a comprehensive spine finite element model inclusive of intra-abdominal pressure.

METHODS

The effect of changing Young's modulus, abdominal wall thickness, and abdominal radii on abdominal compliance were evaluated. Intra-abdominal pressure and thoracolumbar fascia forces were also evaluated to assess abdominal physiological changes effects on overall static spinal stability.

FINDINGS

Results showed that as wall thickness increased, compliance decreased. Similar findings were made with an increase in abdominal radius and Young's modulus. Furthermore, the active reduction in compliance, caused by increased elasticity and abdominal radius, resulted in an increase in spinal supportive forces originating from the thoracolumbar fascia and intra-abdominal pressurization, along with an increase in spine displacement from its original stable position. There was no clear stability trend for the case of changing abdominal wall thickness as fluctuations were present.

INTERPRETATION

Investigated mechanics and data trends suggested that dangerously low compliance levels might result from poor abdominal elasticity and thickening fat layers. This led to a direct discussion and recommendations for obesity conditions and laparoscopy applications. Lastly, static spinal stability showed to improve through increasing active abdominal compliance by means of actively engaging abdominal pressure, hence augmenting abdominal active elasticity.

Are anthropometric data a tool for determining the severity of OHSS? Yes, it could be!

BACKGROUND

All management guidelines of ovarian hyperstimulation syndrome (OHSS) recommend daily monitoring of women's body weight, waist circumference and note that as indicators increase, the severity OHSS also increases. However, the dynamics of abdominal size and its relationship with markers of OHSS severity have not been highlighted. The purpose of this study is to assess the usefulness of various anthropometric indicators for determining the degree of OHSS severity as well as paracentesis indications.

METHODS

Observational study including 76 women complaining with OHSS. Clinical history, physical examination, laboratory tests, and ultrasound measurement of the ovarian volume (OV) and ascites index (AsI) were done in all cases. Intra-abdominal pressure (IAP) was assessed using an intravesical manometer. The anteroposterior diameter of the abdomen (APD) and transverse diameter of the abdomen (TS) were measured with a pelvimeter. The APD/TS ratio was calculated.

RESULTS

The APD/TS ratio increased progressively and tended to be the highest in the most symptomatic stage of OHSS (Kruskal-Wallis test, p < 0.001). The median APD/TS was significantly lower in patients with mild OHSS (0.55 [IQR, 0.44-0.64]) compared with severe OHSS (0.87 [IQR, 0.80-0.93]; p < 0.001) or critical OHSS (1.04 [IQR, 1.04-1.13]; p < 0.001). Similarly, the median APD/TS of the moderate OHSS group (0.65 [IQR, 0.61-0.70]) was significantly lower than that of the severe (p < 0.001) and critical OHSS group (p = 0.001). There was a strong positive correlation between APD/TS and IAP (Spearman's r = 0.886, p < 0.01). The APD/TS ratio showed a significant positive correlation with AsI (Spearman's r = 0.695, p < 0.01) and OV (Spearman's r = 0.622, p < 0.01). No significant differences were observed in age, height, weight, body mass index, hip circumference or waist circumference between moderate, severe and critical OHSS groups.

CONCLUSIONS

The APD/TS ratio is related to the severity of OHSS. Monitoring APD/TS dynamics could be a method of indirectly controlling intra-abdominal volume, compliance of the abdominal wall and IAP. In conjunction with clinical and laboratory data, APD/TS might be an indicator for paracentesis.

Hemodynamic pathways of gestational hypertension and preeclampsia

Gestational hypertension and preeclampsia are the 2 main types of hypertensive disorders in pregnancy. Noninvasive maternal cardiovascular function assessment, which helps obtain information from all the components of circulation, has shown that venous hemodynamic dysfunction is a feature of preeclampsia but not of gestational hypertension. Venous congestion is a known cause of organ dysfunction, but its potential role in the pathophysiology of preeclampsia is currently poorly investigated. Body water volume expansion occurs in both gestational hypertension and preeclampsia, and this is associated with the common feature of new-onset hypertension after 20 weeks of gestation. Blood pressure, by definition, is the product of intravascular volume load and vascular resistance (Ohm's law). Fundamentally, hypertension may present as a spectrum of cardiovascular states varying between 2 extremes: one with a predominance of raised cardiac output and the other with a predominance of increased total peripheral resistance. In clinical practice, however, this bipolar nature of hypertension is rarely considered, despite the important implications for screening, prevention, management, and monitoring of disease. This review summarizes the evidence of type-specific hemodynamic profiles in the latent and clinical stages of hypertensive disorders in pregnancy. Gestational volume expansion superimposed on an early gestational closed circulatory circuit in a pressure- or volume-overloaded condition predisposes a patient to the gradual deterioration of overall circulatory function, finally presenting as gestational hypertension or preeclampsia-the latter when venous dysfunction is involved. The eventual phenotype of hypertensive disorder is already predictable from early gestation onward, on the condition of including information from all the major components of circulation into the maternal cardiovascular assessment: the heart, central and peripheral arteries, conductive and capacitance veins, and body water content. The relevance of this approach, outlined in this review, openly invites for more in-depth research into the fundamental hemodynamics of gestational hypertensive disorders, not only from the perspective of the physiologist or the scientist, but also in assistance of clinicians toward understanding and managing effectively these severe complications of pregnancy.

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

BACKGROUND AND OBJECTIVE

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.

CONCLUSIONS

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.

Non-Invasive Intra-Abdominal Pressure Measurement by Means of Transient Radar Method: In Vitro Validation of a Novel Radar-Based Sensor

Intra-abdominal hypertension, defined as an intra-abdominal pressure (IAP) equal to or above 12 mmHg is one of the major risk-factors for increased morbidity (organ failure) and mortality in critically ill patients. Therefore, IAP monitoring is highly recommended in intensive care unit (ICU) patients to predict development of abdominal compartment syndrome and to provide a better care for patients hospitalized in the ICU. The IAP measurement through the bladder is the actual reference standard advocated by the abdominal compartment society; however, this measurement technique is cumbersome, non-continuous, and carries a potential risk for urinary tract infections and urethral injury. Using microwave reflectometry has been proposed as one of the most promising IAP measurement alternatives. In this study, a novel radar-based method known as transient radar method (TRM) has been used to monitor the IAP in an in vitro model with an advanced abdominal wall phantom. In the second part of the study, further regression analyses have been done to calibrate the TRM system and measure the absolute value of IAP. A correlation of -0.97 with a p-value of 0.0001 was found between the IAP and the reflection response of the abdominal wall phantom. Additionally, a quadratic relation with a bias of -0.06 mmHg was found between IAP obtained from the TRM technique and the IAP values recorded by a pressure gauge. This study showed a promising future for further developing the TRM technique to use it in clinical monitoring.

Exocrine drainage in pancreas transplantation: Complications and management

The aim of this minireview is to compare various pancreas transplantation exocrine drainage techniques i.e., bladder vs enteric. Both techniques have different difficulties and complications. Numerous comparisons have been made in the literature between exocrine drainage techniques throughout the history of pancreas transplantation, detailing complications and their impact on graft and patient survival. Specific emphasis has been made on the early postoperative management of these complications and the related surgical infections and their consequences. In light of the results, a number of bladder-drained pancreas grafts required conversion to enteric drainage. As a result of technical improvements, outcomes of the varied enteric exocrine drainage techniques (duodenojejunostomy, duodenoduodenostomy or gastric drainage) have also been discussed i.e., assessing specific risks vs benefits. Pancreatic exocrine secretions can be drained to the urinary or intestinal tracts. Until the late 1990s the bladder drainage technique was used in the majority of transplant centers due to ease of monitoring urine amylase and lipase levels for evaluation of possible rejection. Moreover, bladder drainage was associated at that time with fewer surgical complications, which in contrast to enteric drainage, could be managed with conservative therapies. Nowadays, the most commonly used technique for proper driving of exocrine pancreatic secretions is enteric drainage due to the high rate of urological and metabolic complications associated with bladder drainage. Of note, 10% to 40% of bladder-drained pancreata eventually required enteric conversion at no detriment to overall graft survival. Various surgical techniques were originally described using the small bowel for enteric anastomosis with Roux-en-Y loop or a direct side-to-side anastomosis. Despite the improvements in surgery, enteric drainage complication rates ranging from 2%-20% have been reported. Treatment depends on the presence of any associated complications and the condition of the patient. Intra-abdominal infection represents a potentially very serious problem. Up to 30% of deep wound infections are associated with an anastomotic leak. They can lead not only to high rates of graft loss, but also to substantial mortality. New modifications of established techniques are being developed, such as gastric or duodenal exocrine drainage. Duodenoduodenostomy is an interesting option, in which the pancreas is placed behind the right colon and is oriented cephalad. The main concern of this technique is the challenge of repairing the native duodenum when allograft pancreatectomy is necessary. Identification and prevention of technical failure remains the main objective for pancreas transplantation surgeons. In conclusion, despite numerous techniques to minimize exocrine pancreatic drainage complications e.g., leakage and infection, no universal technique has been standardized. A prospective study/registry analysis may resolve this.

Physiology of intra-abdominal volume during pregnancy

A total of 580 pregnant and 50 puerperal women were included in this cross-sectional study to assess the physiological changes that allow women to adapt to a chronic increase in intra-abdominal pressure during pregnancy. The volume of the uterus, intra-abdominal volume (IAV), visceral and subcutaneous fat was calculated. During pregnancy, the IAV increases up to 1.5 times. Changes in IAV until 24 weeks present a linear relationship (5.2%); thereafter, changes become exponential and, at 40 weeks, IAV increases by 61%. This fact is exclusively related to the progressive growth of the foetus and to the increase in uterine size. At term, the IAV reserve is exhausted, becoming equal the anteroposterior and transverse diameters of the abdomen.In conclusion, the adaptive capabilities of IAV related to the foetal growth are limited by the IAV reserve. The reserve capacity of the IAV and tensile properties of the abdominal wall can be estimated by the dynamics of the anteroposterior and transverse abdominal diameters.IMPACT STATEMENTWhat is already known on this subject? A causal relationship between intra-abdominal hypertension and the development of adverse obstetric and perinatal outcomes has been suggested. Nevertheless, the role of this condition as a leading cause of systemic dysfunction during pregnancy remains unrecognised and underestimated.What do the results of this study add? This study assesses the dynamics of IAV in uncomplicated singleton pregnancies.What are the implications of these findings for clinical practice and/or further research? The study of abdominal pressure indicators such as intra-abdominal volume and compliance will help to a better understand the aetiology, pathophysiology, prognosis and treatment strategies for pregnant women with intra-abdominal hypertension.

New non-invasive device to promote primary closure of the fascia and prevent loss of domain in the open abdomen: a pilot study

Background

Primary closure of the fascia at the conclusion of a stage laparotomy can be a challenging task. Current techniques to medialize the fascial edges in open abdomens entail several trips to the operating room and could result in fascial damage. We conducted a pilot study to investigate a novel non-invasive device for gradual reapproximation of the abdominal wall fascia in the open abdomen.

Methods

Mechanically ventilated patients ≥16 years of age with the abdominal fascia deliberately left open after a midline laparotomy for trauma and acute care surgery were randomized into two groups. Control group patients underwent standard care with negative pressure therapy only. Device group patients were treated with negative pressure therapy in conjunction with the new device for fascial reapproximation. Exclusion criteria: pregnancy, traumatic hernias, pre-existing ventral hernias, burns, and body mass index ≥40 kg/m². The primary outcome was successful fascial closure by direct suture of the fascia without mesh or component separation. Secondary outcomes were abdominal wall complications.

Results

Thirty-eight patients were investigated, 20 in the device group and 18 in the control group. Primary closure of the fascia by direct suture without mesh or component separation was achieved in 17 patients (85%) in the device group and only 10 patients (55.6%) in the control group (p=0.0457). Device group patients were 53% more likely to experience primary fascial closure by direct suture than control group patients. Device group showed gradual reduction (p<0.005) in the size of the fascial defects; not seen in control group. There were no complications related to the device.

Conclusions

The new device applied externally on the abdominal wall promoted reapproximation of the fascia in the midline, preserved the integrity of the fascia, and improved primary fascial closure rate compared with negative pressure therapy system only.

Level of evidence

I, randomized controlled trial.

Prehabilitation of complex ventral hernia patients with Botulinum: a systematic review of the quantifiable effects of Botulinum

PURPOSE

Complex ventral hernia repair (CVHR) encompasses patient optimization, primary fascial closure (PFC), mesh reinforcement and component separation technique (CST), if needed. High rates of complications after CST are still reported. Prehabilitation by managing pre-operative modifiable risk factors, like abdominal wall compliance, possibly reduces these rates. Compliance can be modified by intramuscular injection of Botulinum in the lateral abdominal wall muscles (LAWM). Paralysis leads to elongation of these muscles, which may facilitate PFC and/or prevent CST. Evidence to use Botulinum in hernia patients is scarce and fragmented. An update of evidence for the effect of Botulinum is presented.

METHODS

A multi-database search was conducted for Botulinum studies in ventral hernia patients. A systematic review was performed to describe its primary effect on compliance (LAWM elongation) and secondary effects like PFC ± CST rate, complications and recurrence.

RESULTS

14 studies were included (377 patients) with a HDW of median 12 (10-15) cm. A typical intervention consisted of 200-300 U Botulinum in 3 points per hemi-abdomen under US guidance, > 2 weeks pre-operatively and evaluated by CT just before the operation. The primary effect was a median LAWM elongation of 4.0 cm per side without complications of the injection (four studies, 107 patients). The median PFC rate was 100%, CST rate 38%, wound-related complications 19%, medical complications 18% and recurrence 0% (14 studies).

CONCLUSION

Botulinum safely elongates the abdominal wall muscles, but the level of evidence available remains low. Any patient in whom PFC is expected to be difficult, could be a candidate for prehabilitation with Botulinum.

A Clinician's Guide to Management of Intra-abdominal Hypertension and Abdominal Compartment Syndrome in Critically Ill Patients

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2020. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Factors associated with increased intra-abdominal pressure in patients undergoing cardiac surgery

Background

The aim of this study was to investigate the intra-abdominal pressure changes and risk factors associated with increased intra-abdominal pressure in patients undergoing cardiac surgery.

Methods

Between July 2016 and January 2017, a total of 100 patients (74 males, 26 females; mean age 55.9±14.3 years; range, 19 to 75 years) who underwent cardiac surgery under cardiopulmonary bypass were included in the study. Patients" data including demographic and clinical characteristics and intra- and postoperative data were recorded. Intra-abdominal pressure was measured via a urinary catheter after anesthesia induction, on admission to the intensive care unit, and at postoperative 12 and 24 h. The patients were divided into two groups according to the intraabdominal pressure as Group 1 (≥12 mmHg; n=49) and Group 2 (<12 mmHg; n=51).

Results

In the univariate regression analysis, high intra-abdominal pressure was related to intra-abdominal pressure measured after anesthesia induction (Odds Ratio =0.70, p=0.001), age (odds ratio=0.95, p=0.004), hypertension (odds ratio=4.51, p=0.0001), duration of cardiopulmonary bypass (odds ratio=0.97, p=0.0001), intraoperative lactate levels (odds ratio=0.53, p=0.0001), use of red blood cells (odds ratio=0.24, p=0.0001), use of dopamine (odds ratio=0.21, p=0.002), dobutamine (odds ratio=0.28, p=0.005), use of noradrenaline (odds ratio=0.25, p=0.016), postoperative lactate levels (odds ratio=0.60, p=0.0001), duration of cross-clamp (odds ratio=0.97, p=0.0001), atrial fibrillation (odds ratio=5.89, p=0.004), and acute kidney injury (odds ratio=8.33, p=0.048). In the multivariate analysis, the intra-abdominal pressure at baseline (odds ratio=0.70, p=0.045), age (odds ratio=0.93, p=0.032), hypertension (odds ratio=6.87, p=0.023), duration of cardiopulmonary bypass (odds ratio=0.98, p=0.062), intraoperative lactate levels (odds ratio=0.57, p=0.035), and use of red blood cells (odds ratio=0.19, p=0.003) remained statistically significant.

Conclusion

Our study results suggest that age, hypertension, duration of cardiopulmonary bypass, intraoperative lactate levels, and use of red blood cells are risk factors associated with elevated intra-abdominal pressure in patients undergoing cardiac surgery. Increased awareness of these risk factors and the addition of intra-abdominal pressure measurement to the standard follow-up scheme in patients with variable hemodynamics, low cardiac output, and high lactate levels in the intensive care unit may be useful in early diagnosis of complications and in decreasing morbidity.

Evaluation of Amikacin Pharmacokinetics in Critically Ill Patients with Intra-abdominal Sepsis

Purpose: Although the current widespread use of amikacin is in intra-abdominal sepsis treatment, its pharmacokinetic changes in the present setting are not yet well known. This study was aimed to evaluate the amikacin pharmacokinetic profile in critically ill patients with intraabdominal sepsis compared to pneumosepsis.

Methods: Adult septic patients received amikacin therapy were studied. Patients with intraabdominal sepsis were enrolled in group 1 (n=16), and patients with pneumosepsis were enrolled in group 2 (n=13). The amikacin serum concentrations were evaluated in the first, second, fourth and sixth hours after initiating 30-minute infusion. The pharmacokinetic parameters were calculated for each patient.

Results: There was no significant difference in the volume of distribution between the two groups (0.33±0.08 vs. 0.28±0.10 L/kg, P=0.193). The amikacin clearance was significantly lower in group 1 compared to group 2 (58.5±21.7 vs. 83.9±37.0 mL/min, P=0.029). There was no significant correlation between amikacin clearance and creatinine clearance estimated by Cockcroft-Gault formula in all patients (P=0.206). The half-life was significantly longer in group 1 compared to group 2 (5.3±2.8 vs. 3.4±3.2 hours, P=0.015).

Conclusion: Pathophysiologic changes following intra-abdominal sepsis can affect amikacin pharmacokinetics behavior. The clearance and half-life may change, but the alteration of the volume of distribution is not significantly different in comparison with pneumosepsis. Further studies are required to evaluate the pharmacokinetic variables of amikacin in critically ill patients with intra-abdominal sepsis.

Predictive value of transabdominal intestinal sonography in critically ill patients: a prospective observational study

BACKGROUND

This study examined the feasibility of transabdominal intestinal ultrasonography in evaluating acute gastrointestinal injury (AGI).

METHODS

A total of 116 patients were included. Intestinal ultrasonography was conducted daily within 1 week after admission to the intensive care unit. Ultrasonography indicators including intestinal diameter, changes in the intestinal folds, thickness of the intestinal wall, stratification of the intestinal wall, and intestinal peristalsis (movement of the intestinal contents) were observed to determine the acute gastrointestinal injury ultrasonography (AGIUS) score. The gastrointestinal and urinary tract sonography ultrasound (GUTS) protocol score was also calculated. During the first week of the study, the gastrointestinal failure (GIF) score was determined daily. The correlations between transabdominal intestinal scores (AGIUS and GUTS) and the GIF score were analyzed to clarify the feasibility of evaluating AGI through observation of the intestine. The utility of intestinal ultrasonography indicators in predicting feeding intolerance was investigated to improve the ability of clinicians to manage AGI.

RESULTS

A total of 751 ultrasonic examinations were performed with 511 images (68%) considered to be of "good quality." AGIUS and GUTS scores differed significantly between AGI patients (GIF score 0-2) and non-AGI patients (GIF score 3-4) (p < 0.001). Both scores correlated positively with GIF score (r = 0.54, p < 0.001; r = 0.66, p < 0.001). These ultrasonography indicators could predict feeding intolerance, with an area under the receiver operating characteristic curve of 0.60 (0.48-0.71; intestinal diameter), 0.76 (0.67-0.85; intestinal folds), 0.71 (0.62-0.80; wall thickness), 0.77 (0.69-0.86; wall stratification), and 0.78 (0.68-0.88; intestinal peristalsis). Compared to patients with a normal rate of peristalsis (5-10/min), patients with abnormal peristalsis rates (< 5/min or > 10/min) have increased risk for feeding intolerance (16/83 vs. 25/33, p < 0.001).

CONCLUSIONS

The transabdominal intestinal ultrasonography represents an effective means for assessing gastrointestinal injury in critically ill patients. Intestinal ultrasonography indicators, especially the degree of intestinal peristalsis, may be used to predict feeding intolerance.

TRIAL REGISTRATION

ClinicalTrial.gov, NCT03589248. Registered 04 July 2018-retrospectively registered.

Management of peripartum intra-abdominal hypertension and abdominal compartment syndrome

Normal pregnancy leads to a state of chronically increased intra-abdominal pressure. Obstetric and non-obstetric conditions may increase intra-abdominal pressure further, causing intra-abdominal hypertension and abdominal compartment syndrome, which leads to maternal organ dysfunction and a compromised fetal state. Limited medical literature exists to guide treatment of pregnant women with these conditions. In this state-of-the-art review, we propose a diagnostic and treatment algorithm for the management of peripartum intra-abdominal hypertension and abdominal compartment syndrome, informed by newly available studies.

Ventilation in patients with intra-abdominal hypertension: what every critical care physician needs to know

The incidence of intra-abdominal hypertension (IAH) is high and still underappreciated by critical care physicians throughout the world. One in four to one in three patients will have IAH on admission, while one out of two will develop IAH within the first week of Intensive Care Unit stay. IAH is associated with high morbidity and mortality. Although considerable progress has been made over the past decades, some important questions remain regarding the optimal ventilation management in patients with IAH. An important first step is to measure intra-abdominal pressure (IAP). If IAH (IAP > 12 mmHg) is present, medical therapies should be initiated to reduce IAP as small reductions in intra-abdominal volume can significantly reduce IAP and airway pressures. Protective lung ventilation with low tidal volumes in patients with respiratory failure and IAH is important. Abdominal-thoracic pressure transmission is around 50%. In patients with IAH, higher positive end-expiratory pressure (PEEP) levels are often required to avoid alveolar collapse but the optimal PEEP in these patients is still unknown. During recruitment manoeuvres, higher opening pressures may be required while closely monitoring oxygenation and the haemodynamic response. During lung-protective ventilation, whilst keeping driving pressures within safe limits, higher plateau pressures than normally considered might be acceptable. Monitoring of the respiratory function and adapting the ventilatory settings during anaesthesia and critical care are of great importance. This review will focus on how to deal with the respiratory derangements in critically ill patients with IAH.

Abdominal Compliance and Laparoscopy: A Review

Background and Objectives

Creating and maintaining a pneumoperitoneum to perform laparoscopy is governed by gas laws and the limiting physical constraints of the abdomen.

Methods

A review of how gas, biomechanical and physical properties affect the abdomen and a systematic structured Medline and PubMed search was conducted to identify relevant studies related to the topic.

Results

Abdominal compliance is a measure of ease of abdominal expansion and is determined by the elasticity of the abdominal wall and diaphragm. It is the change in intra-abdominal volume per change in intra-abdominal pressure. Caution should be exercised with pressures exceeding 12 millimeters mercury since this is defined as intra-abdominal hypertension.

Conclusions

Abdominal compliance has its limits, is unique for each patient and pressure-volume curves cannot be easily predicted. Using the lowest possible pressure to accomplish the surgical task without compromising surgical outcome is the desired goal. The clinical importance is caution and knowing there is a point where more pressure does not increase working space and only increases pressure.

A multifaceted individualized pneumoperitoneum strategy for laparoscopic colorectal surgery: a multicenter observational feasibility study

BACKGROUND

While guidelines for laparoscopic abdominal surgery advise using the lowest possible intra-abdominal pressure, commonly a standard pressure is used. We evaluated the feasibility of a predefined multifaceted individualized pneumoperitoneum strategy aiming at the lowest possible intra-abdominal pressure during laparoscopic colorectal surgery.

METHODS

Multicenter prospective study in patients scheduled for laparoscopic colorectal surgery. The strategy consisted of ventilation with low tidal volume, a modified lithotomy position, deep neuromuscular blockade, pre-stretching of the abdominal wall, and individualized intra-abdominal pressure titration; the effect was blindly evaluated by the surgeon. The primary endpoint was the proportion of surgical procedures completed at each individualized intra-abdominal pressure level. Secondary endpoints were the respiratory system driving pressure, and the estimated volume of insufflated CO2 gas needed to perform the surgical procedure.

RESULTS

Ninety-two patients were enrolled in the study. Fourteen cases were converted to open surgery for reasons not related to the strategy. The intervention was feasible in all patients and well-accepted by all surgeons. In 61 out of 78 patients (78%), surgery was performed and completed at the lowest possible IAP, 8 mmHg. In 17 patients, IAP was raised up to 12 mmHg. The relationship between IAP and driving pressure was almost linear. The mean estimated intra-abdominal CO2 volume at which surgery was performed was 3.2 L.

CONCLUSION

A multifaceted individualized pneumoperitoneum strategy during laparoscopic colorectal surgery was feasible and resulted in an adequate working space in most patients at lower intra-abdominal pressure and lower respiratory driving pressure. ClinicalTrials.gov (Trial Identifier: NCT03000465).

Effect of decompressive laparotomy on organ function in patients with abdominal compartment syndrome: a systematic review and meta-analysis

BACKGROUND

Decompressive laparotomy has been advised as potential treatment for abdominal compartment syndrome (ACS) when medical management fails; yet, the effect on parameters of organ function differs markedly in the published literature. In this study, we sought to investigate the effect of decompressive laparotomy on intra-abdominal pressure and organ function in critically ill adult and pediatric patients with ACS, specifically focusing on hemodynamic, respiratory, and kidney function and outcome.

METHODS

A systematic review and meta-analysis of the literature was performed. Articles reporting data on intra-abdominal pressure (IAP), hemodynamic (mean arterial pressures [MAP], central venous pressure [CVP], cardiac index [CI], heart rate [HR], systemic vascular resistance index [SVRI] and/or pulmonary capillary wedge pressure [PCWP]), respiratory (positive end-expiratory pressure [PEEP], peak inspiratory pressure [PIP] and/or ratio of partial pressure arterial oxygen and fraction of inspired oxygen [P/F ratio]), and/or urinary output (UO) following decompressive laparotomy were analyzed.

RESULTS

A total of 15 articles were included; 3 included children only (aged 18 years or younger). Of the 286 patients who were included, 49.7% had primary ACS. The baseline mean IAP in adults decreased with an average of 18.2 ± 6.5 mmHg following decompression, from 31.7 ± 6.4 mmHg to 13.5 ± 3.0 mmHg. There was a decrease in HR (12.2 ± 9.5 beats/min; p = 0.04), CVP (4.6 ± 2.3 mmHg; p = 0.022), PCWP (5.8 ± 2.3 mmHg; p = 0.029), and PIP (10.1 ± 3.9 cmH2O; p < 0.001) and a mean increase in P/F ratio (70.4 ± 49.4; p < 0.001) and UO (95.3 ± 105.3 ml/h; p < 0.001). In children, there was a significant increase in MAP (20.0 ± 2.3 mmHg; p = 0.006), P/F ratio (238.2; p < 0.001), and UO (2.88 ± 0.64 ml/kg/h; p < 0.001) and a decrease in CVP (7 mmHg; p = 0.016) and PIP (9.9 cmH2O; p = 0.002). The overall mortality rate was 49.7% in adults and 60.8% in children following decompressive laparotomy.

CONCLUSIONS

Decompressive laparotomy resulted in a significantly lower IAP and had beneficial effects on hemodynamic, respiratory, and renal parameters. Mortality after decompressive laparotomy remains high in both adults and children.

Large-volume paracentesis effects plasma disappearance rate of indo-cyanine green in critically ill patients with decompensated liver cirrhosis and intraabdominal hypertension

BACKGROUND

Ascites is a major complication of decompensated liver cirrhosis. Intraabdominal hypertension and structural alterations of parenchyma involve decisive changes in hepatosplanchnic blood flow. Clearance of indo-cyanine green (ICG) is mainly dependent on hepatic perfusion and hepatocellular function. As a consequence, plasma disappearance rate of ICG (ICG-PDR) is rated as a useful dynamic parameter of liver function. This study primarily evaluates the impact of large-volume paracentesis (LVP) on ICG-PDR in critically ill patients with decompensated cirrhosis. Additionally, it describes influences on intraabdominal pressure (IAP), abdominal perfusion pressure (APP), hepatic blood flow, hemodynamic and respiratory function.

METHODS

We analyzed LVP in 22 patients with decompensated liver cirrhosis. ICG-PDR was assessed by using noninvasive LiMON technology (Pulsion® Medical Systems; Maquet Getinge Group), and hepatic blood flow was analyzed by color-coded duplex sonography.

RESULTS

Paracentesis of a median volume of 3450 mL ascites evoked significant increases of ICG-PDR from 3.6 (2.8-4.6) to 5.1 (3.9-6.2)%/min (p < 0.001). Concomitantly, we observed a raise in "ICG-Clearance" from 99 (73.5-124.5) to 104 (91-143.5) mL/min/m2 (p = 0.005), while circulating blood volume index was unchanged [2412 (1983-3025) before paracentesis vs. 2409 (1997-2805) mL/m2, p = 0.734]. Sonography revealed a significant impact of paracentesis on hepatic blood flow: Hepatic artery resistance index dropped from 0.74 (0.68-0.75) to 0.68 (0.65-0.71) (p < 0.001) and maximum flow velocity in hepatic vein increased from 24 (17-30) to 30 (22-36) cm/s (p < 0.001). Consistent with previous studies, paracentesis caused significant decreases in IAP from 19.0 (15.0-20.3) to 11.0 (8.8-12.3) mmHg (p < 0.001) and central venous pressure from 22.5 (17.8-29.0) to 17.5 (12.8-24.0) mmHg (p < 0.001) with inverse increases in APP from 63.0 (56.8-69.5) to 71.0 (65.5-78.5) mmHg (p < 0.001). Changes in ICG-PDR were concomitant with changes in IAP (r = - 0.602) and APP (r = 0.576). Moreover, we found a substantial improvement in respiratory function. By contrast, hemodynamic parameters assessed by transpulmonary thermodilution, serum bilirubin and international normalized ratio did not change after paracentesis.

CONCLUSION

Critically ill patients with decompensated cirrhosis and elevated IAP showed dramatically impaired ICG-PDR. Paracentesis evoked an improvement in ICG-PDR in parallel with a decreased IAP and an increased APP, while conventional parameters of liver function did not change. This effect on ICG-PDR is mainly referable to a relief of intraabdominal hypertension and changes in hepatosplanchnic blood flow.

Principles of fluid management and stewardship in septic shock: it is time to consider the four D's and the four phases of fluid therapy

In patients with septic shock, the administration of fluids during initial hemodynamic resuscitation remains a major therapeutic challenge. We are faced with many open questions regarding the type, dose and timing of intravenous fluid administration. There are only four major indications for intravenous fluid administration: aside from resuscitation, intravenous fluids have many other uses including maintenance and replacement of total body water and electrolytes, as carriers for medications and for parenteral nutrition. In this paradigm-shifting review, we discuss different fluid management strategies including early adequate goal-directed fluid management, late conservative fluid management and late goal-directed fluid removal. In addition, we expand on the concept of the “four D’s” of fluid therapy, namely drug, dosing, duration and de-escalation. During the treatment of patients with septic shock, four phases of fluid therapy should be considered in order to provide answers to four basic questions. These four phases are the resuscitation phase, the optimization phase, the stabilization phase and the evacuation phase. The four questions are “When to start intravenous fluids?”, “When to stop intravenous fluids?”, “When to start de-resuscitation or active fluid removal?” and finally “When to stop de-resuscitation?” In analogy to the way we handle antibiotics in critically ill patients, it is time for fluid stewardship.

Characterization and correction of intraoperative soft tissue deformation in image-guided laparoscopic liver surgery

Laparoscopic liver surgery is challenging to perform due to a compromised ability of the surgeon to localize subsurface anatomy in the constrained environment. While image guidance has the potential to address this barrier, intraoperative factors, such as insufflation and variable degrees of organ mobilization from supporting ligaments, may generate substantial deformation. The severity of laparoscopic deformation in humans has not been characterized, and current laparoscopic correction methods do not account for the mechanics of how intraoperative deformation is applied to the liver. We first measure the degree of laparoscopic deformation at two insufflation pressures over the course of laparoscopic-to-open conversion in 25 patients. With this clinical data alongside a mock laparoscopic phantom setup, we report a biomechanical correction approach that leverages anatomically load-bearing support surfaces from ligament attachments to iteratively reconstruct and account for intraoperative deformations. Laparoscopic deformations were significantly larger than deformations associated with open surgery, and our correction approach yielded subsurface target error of [Formula: see text] and surface error of [Formula: see text] using only sparse surface data with realistic surgical extent. Laparoscopic surface data extents were examined and found to impact registration accuracy. Finally, we demonstrate viability of the correction method with clinical data.

Intraabdominal Hypertension, Abdominal Compartment Syndrome, and the Open Abdomen

Abdominal compartment syndrome (ACS) is the end point of a process whereby massive interstitial swelling in the abdomen or rapid development of a space-filling lesion in the abdomen (such as ascites or a hematoma) leads to pathologically increased pressure. This results in so-called intraabdominal hypertension (IAH), causing decreased perfusion of the kidneys and abdominal viscera and possible difficulties with ventilation and maintenance of cardiac output. These effects contribute to a cascade of ischemia and multiple organ dysfunction with high mortality. A few primary disease processes traditionally requiring large-volume crystalloid resuscitation account for most cases of IAH and ACS. Once IAH is recognized, nonsurgical steps to decrease intraabdominal pressure (IAP) can be undertaken (diuresis/dialysis, evacuation of intraluminal bowel contents, and sedation), although the clinical benefit of such therapies remains largely conjectural. Surgical decompression with midline laparotomy is the standard ultimate treatment once ACS with organ dysfunction is established. There is minimal primary literature on the pathophysiological underpinnings of IAH and ACS and few prospective randomized trials evaluating their treatment or prevention; this concise review therefore provides only brief summaries of these topics. Many modern studies nominally dealing with IAH or ACS are simply epidemiologic surveys on their incidence, so this paper summarizes the incidence of IAH and ACS in a variety of disease states. Especially emphasized is the fact that modern critical care paradigms emphasize rational limitations to fluid resuscitation, which may have contributed to an apparent decrease in ACS among critically ill patients.

The passive leg raising test to guide fluid removal in critically ill patients

Background

To investigate whether haemodynamic intolerance to fluid removal during intermittent renal replacement therapy (RRT) in critically ill patients can be predicted by a passive leg raising (PLR) test performed before RRT.

Methods

We included 39 patients where intermittent RRT with weight loss was decided. Intradialytic hypotension was defined as hypotension requiring a therapeutic intervention, as decided by the physicians in charge. Before RRT, the maximal increase in cardiac index (CI, pulse contour analysis) induced by a PLR test was recorded. RRT was then started.

Results

Ultrafiltration rate was similar in patients with and without intradialytic hypotension. Thirteen patients presented intradialytic hypotension, while 26 did not. In patients with intradialytic hypotension, it occurred 120 min [interquartile range 60–180 min] after onset of RRT. In the 26 patients without intradialytic hypotension, the PLR test induced no significant change in CI. Conversely, in patients with intradialytic hypotension, PLR significantly increased CI by 15 % [interquartile range 11–36 %]. The PLR-induced increase in CI predicted intradialytic hypotension with an area under the ROC curve of 0.89 (95 % interval confidence 0.75–0.97) (p < 0.05 from 0.50). The best diagnostic threshold was 9 %. The sensitivity was 77 % (95 % confidence interval 46–95 %), the specificity was 96 % (80–100 %), the positive predictive value was 91 % (57–100 %), and the negative predictive value was 89 % (72–98 %). Compared to patients without intolerance to RRT, CI decreased significantly faster in patients with intradialytic hypotension, with a slope difference of −0.17 L/min/m²/h.

Conclusion

The presence of preload dependence, as assessed by a positive PLR test before starting RRT with fluid removal, predicts that RRT will induce haemodynamic intolerance.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-016-0149-1) contains supplementary material, which is available to authorized users.