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.

Humulus lupus extract rich in xanthohumol improves the clinical course in critically ill COVID-19 patients.

BACKGROUND: The systemic inflammatory response following severe COVID-19 is associated with poor outcomes. Several anti-inflammatory medications have been studied in COVID-19 patients. Xanthohumol (Xn), a natural extract from hop cones, possesses strong anti-inflammatory and antioxidative properties. The aim of this study was to analyze the effect of Xn on the inflammatory response and the clinical outcome of COVID-19 patients. METHODS: Adult patients treated for acute respiratory failure (PaO2/FiO2 less than 150) were studied. Patients were randomized into two groups: Xn - patients receiving adjuvant treatment with Xn at a daily dose of 4.5 mg/kg body weight for 7 days, and C - controls. Observations were performed at four time points: immediately after admission to the ICU and on the 3rd, 5th, and 7th days of treatment. The inflammatory response was assessed based on the plasma IL-6 concentration, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), C-reactive protein (CRP) and D-dimer levels. The mortality rate was determined 28 days after admission to the ICU. RESULTS: Seventy-two patients were eligible for the study, and 50 were included in the final analysis. The mortality rate was significantly lower and the clinical course was shorter in the Xn group than in the control group (20% vs. 48%, p < 0.05, and 9 ± 3 days vs. 22 ± 8 days, p < 0.001). Treatment with Xn decreased the plasma IL-6 concentration (p < 0.01), D-dimer levels (p < 0.05) and NLR (p < 0.01) more significantly than standard treatment alone. CONCLUSION: Adjuvant therapy with Xn appears to be a promising anti-inflammatory treatment in COVID-19 patients.

Endothelial glycocalyx damage in patients with severe COVID-19 on mechanical ventilation - A prospective observational pilot study.

BACKGROUND: Coronavirus disease (COVID-19) associated endotheliopathy and microvascular dysfunction are of concern. OBJECTIVE: The objective of the present single-center observational pilot study was to compare endothelial glycocalyx (EG) damage and endotheliopathy in patients with severe COVID-19 (COVID-19 group) with patients with bacterial pneumonia with septic shock (non-COVID group). METHODS: Biomarkers of EG damage (syndecan-1), endothelial cells (EC) damage (thrombomodulin), and activation (P-selectin) were measured in blood on three consecutive days from admission to the intensive care unit (ICU). The sublingual microcirculation was studied by Side-stream Dark Field (SDF) imaging with automatic assessment. RESULTS: We enrolled 13 patients in the non-COVID group (mean age 70 years, 6 women), and 15 in the COVID-19 group (64 years old, 3 women). The plasma concentrations of syndecan-1 were significantly higher in the COVID-19 group during all three days. Differences regarding other biomarkers were not statistically significant. The assessment of the sublingual microcirculation showed improvement on Day 2 in the COVID-19 group. Plasma levels of C-reactive protein (CRP) were significantly higher on the first two days in the COVID-19 group. Plasma syndecan-1 and CRP were higher in patients suffering from severe COVID-19 pneumonia compared to bacterial pneumonia patients. CONCLUSIONS: These findings support the role of EG injury in the microvascular dysfunction in COVID-19 patients who require ICU.

Haemodynamic monitoring and management in COVID-19 intensive care patients: an International survey.

PURPOSE: To survey haemodynamic monitoring and management practices in intensive care patients with the coronavirus disease 2019 (COVID-19). METHODS: A questionnaire was shared on social networks or via email by the authors and by Anaesthesia and/or Critical Care societies from France, Switzerland, Belgium, Brazil, and Portugal. Intensivists and anaesthetists involved in COVID-19 ICU care were invited to answer 14 questions about haemodynamic monitoring and management. RESULTS: Globally, 1000 questionnaires were available for analysis. Responses came mainly from Europe (n = 460) and America (n = 434). According to a majority of respondents, COVID-19 ICU patients frequently or very frequently received continuous vasopressor support (56%) and had an echocardiography performed (54%). Echocardiography revealed a normal cardiac function, a hyperdynamic state (43%), hypovolaemia (22%), a left ventricular dysfunction (21%) and a right ventricular dilation (20%). Fluid responsiveness was frequently assessed (84%), mainly using echo (62%), and cardiac output was measured in 69%, mostly with echo as well (53%). Venous oxygen saturation was frequently measured (79%), mostly from a CVC blood sample (94%). Tissue perfusion was assessed biologically (93%) and clinically (63%). Pulmonary oedema was detected and quantified mainly using echo (67%) and chest X-ray (61%). CONCLUSION: Our survey confirms that vasopressor support is not uncommon in COVID-19 ICU patients and suggests that different haemodynamic phenotypes may be observed. Ultrasounds were used by many respondents, to assess cardiac function but also to predict fluid responsiveness and quantify pulmonary oedema. Although we observed regional differences, current international guidelines were followed by most respondents.

Unidentified cachexia patients in the oncologic setting: Cachexia UFOs do exist.

OBJECTIVES: Cachexia is an important outcome-modulating parameter in patients with cancer. In the context of a randomized controlled trial on cachexia and nutritional therapy, the TiCaCONCO (Tight Caloric Control in the Cachectic Oncologic Patient) trial, the contacts between patients with cancer and health care practitioners and oncologists were screened. The aim of this retrospective study was to identify in the charts the input of data on body weight (necessary to identify cachexia stage), relevant nutritional data, and nutritional interventions triggered or implemented by oncologists and dietitians. METHODS: In a tertiary, university oncology setting, over a time span of 8 mo (34 wk), the charts of patients admitted to an oncology, gastroenterology, or abdominal surgery unit were screened for the presence of information contributing to a cancer cachexia diagnosis. Data (patient characteristics, tumor type, and location) was gathered. RESULTS: We analyzed 9694 files. Data on body weight was present for >90% of patients. Of the 9694 screening, 118 new diagnoses of cancer were present (1.22% of patient contacts). Information on weight evolution or nutritional status was absent for 54 patients (46%). In contacts between oncologists and patients with cancer, at the time of diagnosis, cachexia was present in 50 patients (42%). In 7 of these patients (14%), no nutritional information was present in the notes. Of the 50 patients with cachexia, only 8 (16%) had a nutritional intervention initiated by the physician. Nutritional interventions were documented in the medical note in 11 patients (9%) in the overall study population. Dietitians made notes regarding nutrition and weight for 49 patients (42%). We could not demonstrate a difference in mortality between cachectic and non-cachectic patients, although numbers are small for analysis. CONCLUSION: Patients newly diagnosed with cancer are not systematically identified as being cachectic and if they are, interventions in the field of nutrition therapy are largely lacking. Important barriers exist between oncologists and dietitians, the former being mandatory to the success of a nutrition trial in cancer.

Intra-abdominal hypertension increases spatial QRS-T angle and elevates ST-segment J-point in healthy women undergoing laparoscopic surgery.

BACKGROUND: Intra-abdominal hypertension (IAH) impairs cardiovascular function, however an effect of IAH on cardiac electrophysiology has been poorly documented. The aim of this study was to evaluate the effect of IAH following pneumoperitoneum on vectorcardiographic variables reflecting cardiac repolarisation and depolarisation. METHODS: Otherwise healthy women undergoing elective gynaecological laparoscopy were studied. Intra-abdominal pressure (IAP), spatial QRS-T angle and ST-segment J-point (STJ) were observed during surgery and the early postoperative period. RESULTS: Forty women, ages 22 to 43 were examined. Induction of IAH to 15mmHg significantly widened the spatial QRS-T angle, whereas the Trendelenburg position subsequently reduced this widening. IAH also increased STJ voltage in leads III, aVF, V2 and V3 during surgery, with increased STJ voltage persisting in several leads through the morning of postoperative day 1. CONCLUSION: Induction of IAH impacts the relationship between cardiac depolarisation and repolarisation and increases spatial QRS-T angle and STJ voltage.

Awareness and knowledge of intra-abdominal hypertension and abdominal compartment syndrome: results of an international survey.

BACKGROUND: Surveys have demonstrated a lack of physician awareness of intra-abdominal hypertension and abdominal compartment syndrome (IAH/ACS) and wide variations in management of these conditions, with many intensive care units (ICUs) reporting that they do not measure intra-abdominal pressure (IAP). We sought to determine the association between publication of the 2006/2007 World Society of the Abdominal Compartment Syndrome (WSACS) Consensus Definitions and Guidelines and IAH/ACS clinical awareness and management. METHODS: The WSACS Executive Committee created an interactive online survey with 53 questions, accessible from November 2006 until December 2008. The survey was endorsed by the WSACS, the European Society of Intensive Care Medicine (ESICM) and the Society of Critical Care Medicine (SCCM). A link to the survey was emailed to all members of the supporting societies. Participants of the 3rd World Congress on Abdominal Compartment Syndrome meeting (March 2007, Antwerp, Belgium) were also asked to complete the questionnaire. No reminders were sent. Based on 13 knowledge questions an overall score was calculated (expressed as percentage). RESULTS: A total of 2244 of the approximately 10,000 clinicians sent the survey responded (response rate, 22.4%). Most of the 2244 respondents (79.2%) completing the survey were physicians or physicians in training and the majority were residing in North America (53.0%). The majority of responders (85%) were familiar with IAP/IAH/ACS, but only 28% were aware of the WSACS consensus definitions for IAH/ACS. Three quarters of respondents considered the cut-off for IAH to be at least 15 mm Hg, and nearly two thirds believed the cut-off for ACS was higher than the currently suggested consensus definition (20 mm Hg). In 67.8% of respondents, organ dysfunction was only considered a problem with IAP of 20 mm Hg or higher. IAP was measured most frequently via the bladder (91.9%), but the majority reported that they instilled volumes well above the current guidelines. Surgical decompression was frequently used to treat IAH/ACS, whereas medical management was only attempted by about half of the respondents. Decisions to decompress the abdomen were predominantly based on the severity of IAP elevation and presence of organ dysfunction (74.4%). Overall knowledge scores were low (43 ± 15%), respondents that were aware of the WSACS had a better score compared to those who were not (49.6% vs. 38.6%, P < 0.001). CONCLUSIONS: This survey showed that although most responding clinicians claim to be familiar with IAH and ACS, knowledge of published consensus definitions, measurement techniques, and clinical management are inadequate.

Prognostic value of serum galactomannan in mixed ICU patients: a retrospective observational study.

BACKGROUND: Little is known about serum galactomannan (GM) testing in (mostly non-neutropenic) mixed intensive care unit (ICU) patients. The aim of this study was to look for the incidence of invasive aspergillosis (IA) in critically ill patients, to validate previously reported GM thresholds, and to evaluate the prognostic value of GM. METHODS: This was a retrospective study of 474 GM samples in 160 patients from the start of January 2003 until the start of February 2004. GM tests were ordered because of a clinical suspicion of IA or on a regular basis in immune compromised patients. The number of samples per patient was 3 ± 2.6. We used the criteria of the European Organisation for Research and Treatment of Cancer (EORTC) to define proven IA, probable IA, and possible IA. The number of positive samples, with GM optical density (OD) > 0.5 was 230 (48.5%). RESULTS: In our study population, five (3%) patients had proven IA, 11 (7%) had probable, 27 (17.5%) had possible, and 116 (72.5%) had no IA. We could not identify a GM threshold for IA with analysis of receiver operating characteristics (ROC) curves: with a sensitivity of (56.3%, 50%, 50%, 37.5%), specificity (38.2%, 67.5%, 68.8%, 72.9%), NPV (88.7%, 91.8%, 92.5%, 91.3%) and PPV (9.2%, 12.9%, 15.1%, 13.3%) for a cut-off of OD > 0.5, > 0.8, > 1.1 and > 1.5 respectively. IA was associated with high mortality of 87.5% and 100% in patients with probable and proven IA respectively. Patients with IA had a significant increase of GM during their stay (GMdelta 0.7 ± 1.5 vs -0.2 ± 1.5, P = 0.027). The overall ICU mortality was 41.9% and the hospital mortality was 58.1%. Patients who died in the ICU and in the hospital had higher APACHE- -II, SAPS-II and SOFA scores (P < 0.0001) and also a significant increase in GM during their stay with 0.27 ± 1.26 (ICU non-survivors) and 0.11 ± 1.55 (hospital non-survivors) compared to a decrease in GM -0.43 ± 1.7 (P = 0.004) and -0.48 ± 1.51 (P = 0.017) in ICU and hospital survivors respectively. Non-survivors also had higher mean GM values but this was not statistically significant. There was a trend towards higher GM values in patients treated with piperacillin/tazobactam (n = 34), but this did not reach statistical significance. Neutropenic patients (n = 31) showed an increase in GM during their stay 0.32 ± 1.3 vs a decrease with -0.43 ± 1.7 in non-neutropenic patients (P = 0.07). Patients on total parenteral nutrition (n = 125) had higher maximal GM levels (1.55 ± 1.94 vs 0.88 ± 1.25, P = 0.058). Patients who were mechanically ventilated had significantly higher mean (P = 0.038) and maximal (P = 0.007) GM levels. CONCLUSIONS: We found a high incidence of proven and probable IA in a group of mixed ICU patients (10%) and the presence of IA was associated with a high mortality. The serum GM antigen detection test may not be useful in the diagnosis of IA in mixed ICU patients, according to the results of the ROC analysis. We could not define a useful threshold.

Continuous veno-venous hemofiltration to adjust fluid volume excess in septic shock patients reduces intra-abdominal pressure.

OBJECTIVE: To analyze the effect and the time course of continuous veno-venous hemofiltration (CVVH) with net ultrafiltration (UF) on intra-abdominal pressure (IAP) body fluid volumes in septic shock patients with acute kidney injury (AKI). METHODS: Patients were studied at baseline and after 6, 12, 24, 48, 72, and 96 hours of CVVH treatment. IAP was measured via the bladder, and abdominal perfusion pressure (APP) was calculated as mean arterial pressure minus IAP. Fluid volume excess (VE), total body water (TBW), extracellular body water (ECW), and intracellular body water (ICW) were derived from wholebody bioimpedance analysis (BIA). RESULTS: 30 patients entered final analysis, of which 6 died during CVVH (non-survivors). Fluid VE, TBW, ECW, ICW, and IAP significantly decreased in 24 survivors, whereas these variables remained essentially unchangedin non-survivors. APP slowly increased in survivors, while it did not change in nonsurvivors. IAP strongly correlated with VEin survivors: The lower the IAP, the lower the fluid volume excess. CONCLUSION: CVVH with net UF successfully reduced IAP, TBW, ECW, and ICW in critically ill patients who survived 96 h of CVVH. Failure to increase APP was associated with fatal outcome, and, finally, IAP correlated with fluid volume excess. BIA could be helpful to monitor fluid status in patients with AKI.

Effect of intra-abdominal pressure on respiratory function in patients undergoing ventral hernia repair.

AIM: To determine the influence of intra-abdominal pressure (IAP) on respiratory function after surgical repair of ventral hernia and to compare two different methods of IAP measurement during the perioperative period. METHODS: Thirty adult patients after elective repair of ventral hernia were enrolled into this prospective study. IAP monitoring was performed via both a balloon-tipped nasogastric probe [intragastric pressure (IGP), CiMON, Pulsion Medical Systems, Munich, Germany] and a urinary catheter [intrabladder pressure (IBP), UnoMeterAbdo-Pressure Kit, UnoMedical, Denmark] on five consecutive stages: (1) after tracheal intubation (AI); (2) after ventral hernia repair; (3) at the end of surgery; (4) during spontaneous breathing trial through the endotracheal tube; and (5) at 1 h after tracheal extubation. The patients were in the complete supine position during all study stages. RESULTS: The IAP (measured via both techniques) increased on average by 12% during surgery compared to AI (P < 0.02) and by 43% during spontaneous breathing through the endotracheal tube (P < 0.01). In parallel, the gradient between РаСО2 and EtCO2 [Р(а-et)CO2] rose significantly, reaching a maximum during the spontaneous breathing trial. The PаO2/FiO2 decreased by 30% one hour after tracheal extubation (P = 0.02). The dynamic compliance of respiratory system reduced intraoperatively by 15%-20% (P < 0.025). At all stages, we observed a significant correlation between IGP and IBP (r = 0.65-0.81, P < 0.01) with a mean bias varying from -0.19 mmHg (2SD 7.25 mmHg) to -1.06 mm Hg (2SD 8.04 mmHg) depending on the study stage. Taking all paired measurements together (n = 133), the median IGP was 8.0 (5.5-11.0) mmHg and the median IBP was 8.8 (5.8-13.1) mmHg. The overall r (2) value (n = 30) was 0.76 (P < 0.0001). Bland and Altman analysis showed an overall bias for the mean values per patient of 0.6 mmHg (2SD 4.2 mmHg) with percentage error of 45.6%. Looking at changes in IAP between the different study stages, we found an excellent concordance coefficient of 94.9% comparing ΔIBP and ΔIGP (n = 117). CONCLUSION: During ventral hernia repair, the IAP rise is accompanied by changes in Р(а-et)CO2 and PаO2/FiO2-ratio. Estimation of IAP via IGP or IBP demonstrated excellent concordance.

Fluid management in critically ill patients: the role of extravascular lung water, abdominal hypertension, capillary leak, and fluid balance.

INTRODUCTION: Capillary leak in critically ill patients leads to interstitial edema. Fluid overload is independently associated with poor prognosis. Bedside measurement of intra-abdominal pressure (IAP), extravascular lung water index (EVLWI), fluid balance, and capillary leak index (CLI) may provide a valuable prognostic tool in mechanically ventilated patients. METHODS: We performed an observational study of 123 mechanically ventilated patients with extended hemodynamic monitoring, analyzing process-of-care variables for the first week of ICU admission. The primary outcome parameter was 28-day mortality. ΔmaxEVLWI indicated the maximum difference between EVLWI measurements during ICU stay. Patients with a ΔmaxEVLWI <-2 mL/kg were called 'responders'. CLI was defined as C-reactive protein (milligrams per deciliter) over albumin (grams per liter) ratio and conservative late fluid management (CLFM) as even-to-negative fluid balance on at least two consecutive days. RESULTS: CLI had a biphasic course. ΔmaxEVLWI was lower if CLFM was achieved and in survivors (-2.4 ± 4.8 vs 1.0 ± 5.5 mL/kg, p = 0.001; -3.3 ± 3.8 vs 2.5 ± 5.3 mL/kg, p = 0.001, respectively). No CLFM achievement was associated with increased CLI and IAPmean on day 3 and higher risk to be nonresponder (odds ratio (OR) 2.76, p = 0.046; OR 1.28, p = 0.011; OR 5.52, p = 0.001, respectively). Responders had more ventilator-free days during the first week (2.5 ± 2.3 vs 1.5 ± 2.3, p = 0.023). Not achieving CLFM and being nonresponder were strong independent predictors of mortality (OR 9.34, p = 0.001 and OR 7.14, p = 0.001, respectively). CONCLUSION: There seems to be an important correlation between CLI, EVLWI kinetics, IAP, and fluid balance in mechanically ventilated patients, associated with organ dysfunction and poor prognosis. In this context, we introduce the global increased permeability syndrome.

Intra-abdominal pressure measurement using the FoleyManometer does not increase the risk for urinary tract infection in critically ill patients.

OBJECTIVE: The aim of this study was to determine whether intra-abdominal pressure (IAP) monitoring using the FoleyManometer (Holtech Medical, Charlottenlund, Denmark) increases the risk of urinary tract infection (UTI). DESIGN: A retrospective database review was conducted. SETTING: The study was conducted in the 12-bed medical intensive care unit of ZNA Stuivenberg Hospital (Antwerp, Belgium), a tertiary hospital. PATIENTS: There were 5,890 patients admitted to the medical intensive care unit of which 1,097 patients underwent intrabladder pressure (IBP) monitoring as estimate for IAP. INTERVENTIONS: Crude and adjusted UTI rates were compared among patients undergoing IAP measurements with three different intrabladder methods: a modified homemade technique, a FoleyManometer with 35 ml reservoir, and a FoleyManometer low volume (FoleyManometerLV) with less than 10 ml priming volume. MEASUREMENTS AND RESULTS: Four consecutive time periods of 24 months were defined and compared with regard to IAP measurement: period 1 (2000-2001), during which IAP monitoring was not used routinely (which serves as a control group), was compared with period 2 (2002-2003), using a modified homemade technique; period 3 (2004-2005), introducing the FoleyManometer; and finally period 4 (2006-2007), in which the FoleyManometerLV was introduced. The incidence of IBP measurements increased from 1.4% in period 1 to 45.4% in period 4 (p < 0.001). At the same time, the Simplified Acute Physiology Score (version 2) (SAPS-II) increased significantly from 24.4 ± 21.5 to 34.9 ± 18.7 (p < 0.001) together with the percentage of ventilated patients from 18.6% to 40.7% (p < 0.001). In total, 1,097 patients had IAP measurements via the bladder. The UTI rates were adjusted for disease severity by multiplying each crude rate with the ratio of control versus study patient SAPS-II probability of mortality. Crude and adjusted UTI rates per 1,000 catheter days (CD) were on average 16.1 and 12.8/1,000 CD, respectively, and were not significantly different between the four time periods. CONCLUSIONS: Intrabladder pressure monitoring as estimate for IAP either via a closed transducer technique or the closed FoleyManometer technique seems safe and does not alter the risk of UTI in critically ill patients.

Aiming for a negative fluid balance in patients with acute lung injury and increased intra-abdominal pressure: a pilot study looking at the effects of PAL-treatment.

INTRODUCTION: Achievement of a negative fluid balance in patients with capillary leak is associated with improved outcome. We investigated the effects of a multi-modal restrictive fluid strategy aiming for negative fluid balance in patients with acute lung injury (ALI). METHODS: In this retrospective matched case-control study, we included 114 mechanically ventilated (MV) patients with ALI. We compared outcomes between a group of 57 patients receiving PAL-treatment (PAL group) and a matched control group, abstracted from a historical cohort. PAL-treatment combines high levels of positive end-expiratory pressure, small volume resuscitation with hyperoncotic albumin, and fluid removal with furosemide (Lasix®) or ultrafiltration. Effects on extravascular lung water index (EVLWI), intra-abdominal pressure (IAP), organ function, and vasopressor therapy were recorded during 1 week. The primary outcome parameter was 28-day mortality. RESULTS: At baseline, no significant intergroup differences were found, except for lower PaO2/FIO2 and increased IAP in the PAL group (174.5 ± 84.5 vs 256.5 ± 152.7, p = 0.001; 10.0 ± 4.2 vs 8.0 ± 3.7 mmHg, p = 0.013, respectively). After 1 week, PAL-treated patients had a greater reduction of EVLWI, IAP, and cumulative fluid balance (-4.2 ± 5.6 vs -1.1 ± 3.7 mL/kg, p = 0.006; -0.4 ± 3.6 vs 1.8 ± 3.8 mmHg, p = 0.007; -1,451 ± 7,761 vs 8,027 ± 5,254 mL, p < 0.001). Repercussions on cardiovascular and renal function were limited. PAL-treated patients required fewer days of intensive care unit admission and days on MV (23.6 ± 15 vs 37.1 ± 19.9 days, p = 0.006; 14.6 ± 10.7 vs 25.5 ± 20.2 days, respectively) and had a lower 28-day mortality (28.1% vs 49.1%, p = 0.034). CONCLUSION: PAL-treatment in patients with ALI is associated with a negative fluid balance, a reduction of EVLWI and IAP, and improved clinical outcomes without compromising organ function.

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

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

Relationship between intra-abdominal pressure and indocyanine green plasma disappearance rate: hepatic perfusion may be impaired in critically ill patients with intra-abdominal hypertension.

BACKGROUND: Monitoring hepatic blood flow and function might be crucial in treating critically ill patients. Intra-abdominal hypertension is associated with decreased abdominal blood flow, organ dysfunction, and increased mortality. The plasma disappearance rate (PDR) of indocyanine green (ICG) is considered to be a compound marker for hepatosplanchnic perfusion and hepatocellular membrane transport and correlates well with survival in critically ill patients. However, correlation between PDRICG and intra-abdominal pressure (IAP) remains poorly understood. The aim of this retrospective study was to investigate the correlation between PDRICG and classic liver laboratory parameters, IAP and abdominal perfusion pressure (APP). The secondary goal was to evaluate IAP, APP, and PDRICG as prognostic factors for mortality. METHODS: A total of 182 paired IAP and PDRICG measurements were performed in 40 critically ill patients. The mean values per patient were used for comparison. The IAP was measured using either a balloon-tipped stomach catheter connected to an IAP monitor (Spiegelberg, Hamburg, Germany, or CiMON, Pulsion Medical Systems, Munich, Germany) or a bladder FoleyManometer (Holtech Medical, Charlottenlund, Denmark). PDRICG was measured at the bedside using the LiMON device (Pulsion Medical Systems, Munich, Germany). Primary endpoint was hospital mortality. RESULTS: There was no significant correlation between PDRICG and classic liver laboratory parameters, but PDRICG did correlate significantly with APP (R = 0.62) and was inversely correlated with IAP (R = -0.52). Changes in PDRICG were associated with significant concomitant changes in APP (R = 0.73) and opposite changes in IAP (R = 0.61). The IAP was significantly higher (14.6 ± 4.6 vs. 11.1 ± 5.3 mmHg, p = 0.03), and PDRICG (10 ± 8.3 vs. 15.9 ± 5.2%, p = 0.02) and APP (43.6 ± 9 vs. 57.9 ± 12.2 mmHg, p < 0.0001) were significantly lower in non-survivors. CONCLUSIONS: PDRICG is positively correlated to APP and inversely correlated to IAP. Changes in APP are associated with significant concomitant changes in PDRICG, while changes in IAP are associated with opposite changes in PDRICG, suggesting that an increase in IAP may compromise hepatosplanchnic perfusion. Both PDRICG and IAP are correlated with outcome. Measurement of PDRICG may be a useful additional clinical tool to assess the negative effects of increased IAP on liver perfusion and function.

Renal replacement therapy with net fluid removal lowers intra-abdominal pressure and volumetric indices in critically ill patients.

BACKGROUND: Little is known about the effects of renal replacement therapy (RRT) with fluid removal on intra-abdominal pressure (IAP). The global end-diastolic volume index (GEDVI) and extravascular lung water index (EVLWI) can easily be measured bedside by transpulmonary thermodilution (TPTD). The aim of this study is to evaluate the changes in IAP, GEDVI and EVLWI in critically ill patients receiving slow extended daily dialysis (SLEDD) or continuous venovenous haemofiltration (CVVH) with the intention of net fluid removal. METHODS: We performed a retrospective cohort study in ICU patients who were treated with SLEDD or CVVH and in whom IAP was also measured, and RRT sessions were excluded when the dose of vasoactive medication needed to be changed between the pre- and post-dialysis TPTD measurements and when net fluid loss did not exceed 500 ml. The TPTD measurements were performed within 2 h before and after SLEDD; in case of CVVH, before and after an interval of 12 h. RESULTS: We studied 25 consecutive dialysis sessions in nine patients with acute renal failure and cardiogenic or non-cardiogenic pulmonary oedema. The GEDVI and EVLWI values before dialysis were 877 ml/m² and 14 ml/kg, respectively. Average net ultrafiltration per session was 3.6 l, with a net fluid loss 1.9 l. The GEDVI decreased significantly during dialysis, but not more than 47.8 ml/m² (p = 0.008), as also did the EVLWI with 1 ml/kg (p = 0.03). The IAP decreased significantly from 12 to 10.5 mmHg (p < 0.0001). CONCLUSIONS: Net fluid removal by SLEDD or CVVH in the range observed in this study decreased IAP, GEDVI and EVLWI in critically ill patients although EVLWI reduction was modest.

Clinical review: Intra-abdominal hypertension: does it influence the physiology of prone ventilation?

Prone ventilation (PV) is a ventilatory strategy that frequently improves oxygenation and lung mechanics in critical illness, yet does not consistently improve survival. While the exact physiologic mechanisms related to these benefits remain unproven, one major theoretical mechanism relates to reducing the abdominal encroachment upon the lungs. Concurrent to this experience is increasing recognition of the ubiquitous role of intra-abdominal hypertension (IAH) in critical illness, of the relationship between IAH and intra-abdominal volume or thus the compliance of the abdominal wall, and of the potential difference in the abdominal influences between the extrapulmonary and pulmonary forms of acute respiratory distress syndrome. The present paper reviews reported data concerning intra-abdominal pressure (IAP) in association with the use of PV to explore the potential influence of IAH. While early authors stressed the importance of gravitationally unloading the abdominal cavity to unencumber the lung bases, this admonition has not been consistently acknowledged when PV has been utilized. Basic data required to understand the role of IAP/IAH in the physiology of PV have generally not been collected and/or reported. No randomized controlled trials or meta-analyses considered IAH in design or outcome. While the act of proning itself has a variable reported effect on IAP, abundant clinical and laboratory data confirm that the thoracoabdominal cavities are intimately linked and that IAH is consistently transmitted across the diaphragm--although the transmission ratio is variable and is possibly related to the compliance of the abdominal wall. Any proning-related intervention that secondarily influences IAP/IAH is likely to greatly influence respiratory mechanics and outcomes. Further study of the role of IAP/IAH in the physiology and outcomes of PV in hypoxemic respiratory failure is thus required. Theories relating inter-relations between prone positioning and the abdominal condition are presented to aid in designing these studies.

Decompressive laparotomy for abdominal compartment syndrome--a critical analysis.

INTRODUCTION: Abdominal compartment syndrome (ACS) is increasingly recognized in critically ill patients, and the deleterious effects of increased intraabdominal pressure (IAP) are well documented. Surgical decompression through a midline laparotomy or decompressive laparotomy remains the sole definite therapy for ACS, but the effect of decompressive laparotomy has not been studied in large patient series. METHODS: We reviewed English literature from 1972 to 2004 for studies reporting the effects of decompressive laparotomy in patients with ACS. The effect of decompressive laparotomy on IAP, patient outcome and physiology were analysed. RESULTS: Eighteen studies including 250 patients who underwent decompressive laparotomy could be included in the analysis. IAP was significantly lower after decompression (15.5 mmHg versus 34.6 mmHg before, p < 0.001), but intraabdominal hypertension persisted in the majority of the patients. Mortality in the whole group was 49.2% (123/250). The effect of decompressive laparotomy on organ function was not uniform, and in some studies no effect on organ function was found. Increased PaO2/FIO2 ratio (PaO2 = partial pressure of oxygen in arterial blood, FiO2 = fraction of inspired oxygen) and urinary output were the most pronounced effects of decompressive laparotomy. CONCLUSION: The effects of decompressive laparotomy have been poorly investigated, and only a small number of studies report its effect on parameters of organ function. Although IAP is consistently lower after decompression, mortality remains considerable. Recuperation of organ dysfunction after decompressive laparotomy for ACS is variable.