Intra-abdominal hypertension: Definitions, monitoring, interpretation and management

Increasing Use of Prophylactic Open Abdomen Therapy With Vacuum Assisted Wound Closure and Mesh Mediated Fascial Traction After Repair of Ruptured Abdominal Aortic Aneurysm

OBJECTIVE

Open abdomen therapy (OAT) is commonly used to prevent or treat abdominal compartment syndrome (ACS) in patients with ruptured abdominal aortic aneurysms (rAAAs). This study aimed to evaluate the incidence, treatment, and outcomes of OAT after rAAA from 2006 to 2021. Investigating data on resuscitation fluid, weight gain, and cumulative fluid balance could provide a more systematic approach to determining the timing of safe abdominal closure.

METHODS

This was a single centre observational cohort study. The study included all patients treated for rAAA followed by OAT from October 2006 to December 2021.

RESULTS

Seventy-two of the 244 patients who underwent surgery for rAAA received OAT. The mean age was 72 ± 7.85 years, and most were male (n = 61, 85%). The most frequent comorbidities were cardiac disease (n = 31, 43%) and hypertension (n = 31, 43%). Fifty-two patients (72%) received prophylactic OAT, and 20 received OAT for ACS (28%). There was a 25% mortality rate in the prophylactic OAT group compared with the 50% mortality in those who received OAT for ACS (p = .042). The 58 (81%) patients who survived until closure had a median of 12 (interquartile range [IQR] 9, 16.5) days of OAT and 5 (IQR 4, 7) dressing changes. There was one case of colocutaneous fistula and two cases of graft infection. All 58 patients underwent successful abdominal closure, with 55 (95%) undergoing delayed primary closure. In hospital survival was 85%. Treatment trends over time showed the increased use of prophylactic OAT (p ≤ .001) and fewer ACS cases (p = .03) assessed by Fisher's exact test. In multivariable regression analysis fluid overload and weight reduction predicted 26% of variability in time to closure.

CONCLUSION

Prophylactic OAT after rAAA can be performed safely, with a high rate of delayed primary closure even after long term treatment.

Stable Gastric Pentadecapeptide BPC 157 Therapy: Effect on Reperfusion Following Maintained Intra-Abdominal Hypertension (Grade III and IV) in Rats

Given in reperfusion, the use of stable gastric pentadecapeptide BPC 157 is an effective therapy in rats. It strongly counteracted, as a whole, decompression/reperfusion-induced occlusion/occlusion-like syndrome following the worst circumstances of acute abdominal compartment and intra-abdominal hypertension, grade III and grade IV, as well as compression/ischemia-occlusion/occlusion-like syndrome. Before decompression (calvariectomy, laparotomy), rats had long-lasting severe intra-abdominal hypertension, grade III (25 mmHg/60 min) (i) and grade IV (30 mmHg/30 min; 40 mmHg/30 min) (ii/iii), and severe occlusion/occlusion-like syndrome. Further worsening was caused by reperfusion for 60 min (i) or 30 min (ii/iii). Severe vascular and multiorgan failure (brain, heart, liver, kidney, and gastrointestinal lesions), widespread thrombosis (peripherally and centrally) severe arrhythmias, intracranial (superior sagittal sinus) hypertension, portal and caval hypertension, and aortal hypotension were aggravated. Contrarily, BPC 157 therapy (10 µg/kg, 10 ng/kg sc) given at 3 min reperfusion times eliminated/attenuated venous hypertension (intracranial (superior sagittal sinus), portal, and caval) and aortal hypotension and counteracted the increases in organ lesions and malondialdehyde values (blood ˃ heart, lungs, liver, kidney ˃ brain, gastrointestinal tract). Vascular recovery promptly occurred (i.e., congested inferior caval and superior mesenteric veins reversed to the normal vessel presentation, the collapsed azygos vein reversed to a fully functioning state, the inferior caval vein-superior caval vein shunt was recovered, and direct blood delivery returned). BPC 157 therapy almost annihilated thrombosis and hemorrhage (i.e., intracerebral hemorrhage) as proof of the counteracted general stasis and Virchow triad circumstances and reorganized blood flow. In conclusion, decompression/reperfusion-induced occlusion/occlusion-like syndrome counteracted by BPC 157 therapy in rats is likely for translation in patients. It is noteworthy that by rapidly counteracting the reperfusion course, it also reverses previous ischemia-course lesions, thus inducing complete recovery.

Intra-abdominal hypertension and abdominal compartment syndrome in acute pancreatitis

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are underrecognized entities in patients of acute pancreatitis (AP). IAH develops in 30% to 60% and ACS in 15% to 30% of all AP patients and they are markers of severe disease with high morbidity and mortality. The detrimental effect of increased IAP has been recognized in several organ systems, including the central nervous system, cardiovascular, respiratory, renal and gastrointestinal systems. The pathophysiology of IAH/ACS development in patients with AP is multifactorial. Pathogenetic mechanisms include over-zealous fluid management, visceral edema, ileus, peripancreatic fluid collections, ascites and retroperitoneal edema. Laboratory and imaging markers are neither sensitive nor specific enough to detect IAH/ACS and intra-abdominal pressure (IAP) monitoring is vital for early diagnosis and the management of patients of AP with IAH/ACS. The treatment of IAH/ACS requires a multi-modality approach with both medical and surgical attention. Medical management consists of nasogastric/rectal decompression, prokinetics, fluid management and diuretics or hemodialysis. If conservative management is not effective, percutaneous drainage of fluid collection or ascites is necessary. Despite medical management, if IAP worsens, surgical decompression is warranted. The review discusses the relevance of IAH/ACS in patients of AP and its management.

Pneumoperitoneum and Acute Kidney Injury-An Integrative Clinical Concept Review

An increased intraabdominal pressure, particularly when occurring during periods of hemodynamic instability or fluid overload, is regarded as a major contributor to acute kidney injury (AKI) in intensive care units. During abdominal laparoscopic procedures, intraoperative insufflation pressures up to 15 mmHg are applied, to enable visualization and surgical manipulation but with the potential to compromise net renal perfusion. Despite the widely acknowledged renal arterial autoregulation, net arterial perfusion pressure is known to be narrow, and the effective renal medullary perfusion is disproportionately impacted by venous and lymphatic congestion. At present, the potential risk factors, mitigators and risk-stratification of AKI during surgical pneumoperitoneum formation received relatively limited attention among nephrologists and represent an opportunity to look beyond mere blood pressure and intake-output balances. Careful charting and reporting duration and extent of surgical pneumoperitoneum represents an opportunity for anesthesia teams to better communicate intraoperative factors affecting renal outcomes for the postoperative clinical teams. In this current article, the authors are integrating preclinical data and clinical experience to provide a better understanding to optimize renal perfusion during surgeries. Future studies should carefully consider intrabdominal insufflation pressure as a key variable when assessing outcomes and blood pressure goals in these settings.

Is it feasible to measure intra-abdominal pressure using a balloon-tipped rectal catheter? Results of a validation study

The gold standard to measure intra-abdominal pressure (IAP) is intra-vesical measurement via the urinary bladder. However, this technique is restricted in ambulatory settings because of the risk of iatrogenic urinary tract infections. Rectal IAP measurements (IAP_rect) may overcome these limitations, but requires validation. This validation study compares the IAP_rect technique against gold standard intra-vesical IAP measurements (IAP_ves). IAP_rect using an air-filled balloon catheter and IAP_ves using Foley Manometer Low Volume were measured simultaneously in sedated and ventilated patients. Measurements were performed twice in different positions (supine and HOB 45° elevated head of bed) and with an external abdominal pressure belt. Sixteen patients were included. Seven were not eligible for analysis due to unreliable IAP_rect values. IAP_rect was significantly higher than IAP_ves for all body positions (p < 0.01) and the correlation between IAP_ves and IAP_rect was poor and not significant in each position (p ≥ 0.25, R² < 0.6, Lin's CCC < 0.8, bias - 8.1 mmHg and precision of 5.6 mmHg with large limits of agreement between - 19 to 2.9 mmHg, high percentage error 67.3%, and low concordance 86.2%). Repeatability of IAP_rect was not reliable (R = 0.539, p = 0.315). For both techniques, measurements with the external abdominal pressure belt were significantly higher compared to those without (p < 0.03). IAP_rect has important shortcomings making IAP estimation using a rectal catheter unfeasible because the numbers cannot be trusted nor validated.

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.

High intra-abdominal pressure during hyperthermic intraperitoneal chemotherapy (HIPEC) following cytoreductive surgery (CRS) for peritoneal surface malignancies

OBJECTIVE

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) represent a mainstay of treatment for peritoneal malignancies. There is evidence that HIPEC using high intra-abdominal pressure (IAP) results in increased tissue penetration, although its safety profile remains relatively unknown. We thus aim to evaluate differences in intra- and post-operative outcomes in patients undergoing CRS-HIPEC with different levels of IAP.

METHODS

This pilot prospective cohort study was conducted from January 2020 to February 2021 with patients undergoing CRS-HIPEC. Low IAP during HIPEC was defined as <18 mmHg and high IAP as ≥18 mmHg. Data was collected on patient and tumor characteristics, intra-operative clinical and biochemical parameters, and immediate post-operative outcomes.

RESULTS

40 patients underwent CRS-HIPEC (n low = 20, n high = 20). Median IAP in the low and high IAP groups were 12.0 and 19.0 mmHg respectively. During HIPEC, both groups experienced increase in heart rate, central venous pressure, end tidal CO2, temperature, and serum glucose, with decrease in mean arterial pressure and base excess. There were no significant differences in hemodynamics between the 2 groups. Mild electrolyte derangements and a decrease in hemoglobin were noted in the high IAP group but were of small magnitude. Post-operatively, high IAP did not result in increased rate of complications, time to full feeds, ICU or total hospital stay.

CONCLUSIONS

High IAP in HIPEC is well tolerated and did not result in additional adverse events.

Intra-Abdominal Hypertension: A Systemic Complication of Severe Acute Pancreatitis

Patients with severe acute pancreatitis (SAP) present complications and organ failure, which require treatment in critical care units. These extrapancreatic complications determine the clinical outcome of the disease. Intra-abdominal hypertension (IAH) deteriorates the prognosis of SAP. In this paper, relevant recent literature was reviewed, as well as the authors’ own experiences, concerning the clinical importance of IAH and its treatment in SAP. The principal observations confirmed that IAH is a frequent consequence of SAP but is practically absent in mild disease. Common manifestations of AP such as pain, abdominal distension, and paralytic ileus contribute to increased abdominal pressure, as well as fluid loss in third space and aggressive fluid replacement therapy. A severe increase in IAP can evolve to abdominal compartment syndrome and new onset organ failure. Conservative measures are useful, but invasive interventions are necessary in several cases. Percutaneous drainage of major collections is preferred when possible, but open decompressive laparotomy is the final possibility in some cases in order to definitively reduce abdominal pressure. Intra-abdominal pressure should be measured in all SAP cases that worsen despite adequate treatment in critical care units. Conservative measures must be introduced to treat IAH, including negative fluid balance, digestive decompression by gastric–rectal tube, and prokinetics, including neostigmine. In the case of insufficient responses to these measures, minimally invasive interventions should be preferred.

Gestational potential space hypothesis: Evolutionary explanation of human females body fat redistribution

Homo sapiens, as well as other primates, developed the evolutionary advantage of storing excess energy as body fat, primarily in the readily accessible visceral fat compartment when food is plentiful for use during scarcity. However, uniquely to female humans, a second transient dimorphic phenotypic change begins at menarche and is reversed by menopause. It is the diversion of visceral fat stores from the abdominal cavity to the gluteofemoral region. The evolutionary purpose for this remains unclear. The author proposes the gestational potential space hypothesis: that such fat diversion is for the reproductive purpose of increasing the potential abdominal space available for gestation and reducing the intra-abdominal pressure. This hypothesis is supported by the basic laws of physics and increased rates of maternal and fetal complications experienced by those with visceral adiposity.

Intra-abdominal pressure correlates with abdominal wall tension during clinical evaluation tests

BACKGROUND

The abdominal muscles play an important respiratory and stabilization role, and in coordination with other muscles regulate the intra-abdominal pressure stabilizing the spine. The evaluation of postural trunk muscle function is critical in clinical assessments of patients with musculoskeletal pain and dysfunction. This study evaluates the relationship between intra-abdominal pressure measured as anorectal pressure with objective abdominal wall tension recorded by mechanical-pneumatic-electronic sensors.

METHODS

In a cross-sectional observational study, thirty-one asymptomatic participants (mean age = 26.77 ± 3.01 years) underwent testing to measure intra-abdominal pressure via anorectal manometry, along with abdominal wall tension measured by sensors attached to a trunk brace (DNS Brace). They were evaluated in five different standing postural-respiratory situations: resting breathing, Valsalva maneuver, Müller's maneuver, instructed breathing, loaded breathing when holding a dumbbell.

FINDINGS

Strong correlations were demonstrated between anorectal manometry and DNS Brace measurements in all scenarios; and DNS Brace values significantly predicted intra-abdominal pressure values for all scenarios: resting breathing (r = 0.735, r² = 0.541, p < 0.001), Valsalva maneuver (r = 0.836, r² = 0.699, p < 0.001), Müller's maneuver (r = 0.651, r² = 0.423, p < 0.001), instructed breathing (r = 0.708, r² = 0.501, p < 0.001), and loaded breathing (r = 0.921, r² = 0.848, p < 0.001).

INTERPRETATION

Intra-abdominal pressure is strongly correlated with, and predicted by abdominal wall tension monitored above the inguinal ligament and in the area of superior trigonum lumbale. This study demonstrates that intra-abdominal pressure can be evaluated indirectly by monitoring the abdominal wall tension.

Computed tomography features predictive of intra-abdominal hypertension in acute necrotizing pancreatitis: A prospective study

BACKGROUND

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) in acute pancreatitis (AP) are associated with development and worsening of organ failures and poor prognosis. Limited studies suggest that contrast-enhanced computed tomography (CECT) can predict the presence of IAH/ACS. We aimed to study clinical profile of patients with AP and IAH and identify predictive factors of IAH on CECT abdomen.

METHODS

Consecutive patients admitted with moderately severe and severe acute pancreatitis (SAP) were recruited. Clinical and radiological data were recorded prospectively. Intra-abdominal pressure was measured via a urinary catheter to document the presence of IAH/ACS. CECT abdomen was done within the first week of admission and various features that may predict the presence of IAH were studied.

RESULTS

Thirty-seven patients (24 SAP) (mean age: 39.78 ± 13.43 years and 67.6% males) with  AP were studied. The most common etiology was alcohol (37.7%). IAH developed in 54.05% of patients; patients with IAH had significantly higher bedside index of severity in AP (BISAP), Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) score, persistent acute lung injury (ALI), persistent acute kidney injury (AKI), persistent cardiovascular failure (CVSF), intensive care unit (ICU) stay, and mortality. Among the CT predictors, patients with IAH more commonly had moderate-gross ascites (60% vs. 23.5%, p-value - 0.026), a pancreatic necrosis of > 50% (50% vs. 17.6%, p-value - 0.04), and a round belly sign (RBS) (50% vs. 5.9%, p-value 0.03). On multivariate analysis, only RBS was predictive of  IAH (odds ratio 12.6, 95% confidence interval 1.3-124.2, p-value 0.03). The sensitivity, specificity, positive predictive value, and negative predictive value for RBS were 50%, 94.12%, 90.9%, and 61.54%, respectively.

CONCLUSION

Presence of RBS, moderate-gross ascites, and pancreatic necrosis of > 50% on CECT can predict the presence of IAH in these groups of patients.

Early Decompressive Laparotomy for Intra-Abdominal Hypertension Following Initiation of Venovenous Extracorporeal Membrane Oxygenation

Patients supported with venovenous extracorporeal membrane oxygenation are at risk for intra-abdominal hypertension and abdominal compartment syndrome. Flow through the return cannula may be compromised in these patients, resulting in inadequate support and end-organ malperfusion. Early decompressive laparotomy can mitigate these complications and potentially improve outcomes. Here we review a series of nine patients undergoing early decompressive laparotomy for abdominal compartment syndrome at a single institution and propose an algorithmic approach to the management of these patients.

Vasopressors in septic shock: which, when, and how much?

In addition to fluid resuscitation, the vasopressor therapy is a fundamental treatment of septic shock-induced hypotension as it aims at correcting the vascular tone depression and then at improving organ perfusion pressure. Experts’ recommendations currently position norepinephrine (NE) as the first-line vasopressor in septic shock. Vasopressin and its analogues are only second-line vasopressors as strong recent evidence suggests no benefit of their early administration in spite of promising preliminary data. Early administration of NE may allow achieving the initial mean arterial pressure (MAP) target faster and reducing the risk of fluid overload. The diastolic arterial pressure (DAP) as a marker of vascular tone, helps identifying the patients who need NE urgently. Available data suggest a MAP of 65 mmHg as the initial target but a more individualized approach is often required depending on several factors such as history of chronic hypertension or value of central venous pressure (CVP). In cases of refractory hypotension, increasing NE up to doses ≥1 µg/kg/min could be an option. However, current experts’ guidelines suggest to combine NE with other vasopressors such as vasopressin, with the intent to rising the MAP to target or to decrease the NE dosage.

Effect of moderate elevated intra-abdominal pressure on lung mechanics and histological lung injury at different positive end-expiratory pressures

INTRODUCTION

Intra-abdominal hypertension (IAH) is a well-known phenomenon in critically ill patients. Effects of a moderately elevated intra-abdominal pressure (IAP) on lung mechanics are still not fully analyzed. Moreover, the optimal positive end-expiratory pressure (PEEP) in elevated IAP is unclear.

METHODS

We investigated changes in lung mechanics and transformation in histological lung patterns using three different PEEP levels in eighteen deeply anesthetized pigs with an IAP of 10 mmHg. After establishing the intra-abdominal pressure, we randomized the animals into 3 groups. Each of n = 6 (Group A = PEEP 5, B = PEEP 10 and C = PEEP 15 cmH2O). End-expiratory lung volume (EELV/kg body weight (bw)), pulmonary compliance (Cstat), driving pressure (ΔP) and transpulmonary pressure (ΔPL) were measured for 6 hours. Additionally, the histological lung injury score was calculated.

RESULTS

Comparing hours 0 and 6 in group A, there was a decrease of EELV/kg (27±2 vs. 16±1 ml/kg; p<0.05) and of Cstat (42±2 vs. 27±1 ml/cmH2O; p<0.05) and an increase of ΔP (11±0 vs. 17±1 cmH2O; p<0.05) and ΔPL (6±0 vs. 10±1 cmH2O; p<0.05). In group B, there was no significant change in EELV/kg (27±3 vs. 24±3 ml/kg), but a decrease in Cstat (42±3 vs. 32±1 ml/cmH20; p<0.05) and an increase in ΔP (11±1 vs. 15±1 cmH2O; p<0.05) and ΔPL (5±1 vs. 7±0 cmH2O; p<0.05). In group C, there were no significant changes in EELV/kg (27±2 vs. 29±3 ml/kg), ΔP (10±1 vs. 12±1 cmH2O) and ΔPL (5±1 vs. 7±1 cmH2O), but a significant decrease of Cstat (43±1 vs. 37±1 ml/cmH2O; p<0.05). Histological lung injury score was lowest in group B.

CONCLUSIONS

A moderate elevated IAP of 10 mmHg leads to relevant changes in lung mechanics during mechanical ventilation. In our study, a PEEP of 10 cmH2O was associated with a lower lung injury score and was able to overcome the IAP induced alterations of EELV.

Hemodynamic and respiratory implications of high intra-abdominal pressure during HIPEC

BACKGROUND

cytoreduction surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) is currently the standard of care for some peritoneal surface malignancies. There is experimental evidence supporting that high Intra Abdominal Pressure (IAP) during HIPEC could enhance the uptake of drugs by tumor tissues. However, few papers are describing the hemodynamic and respiratory effects of increased IAP during HIPEC.

AIMS

to evaluate the hemodynamic and respiratory association with different IAPs during HIPEC.

METHODS

This is part of an IRB board approved prospective randomized controlled trial conducted at The National Tumor Institute of Milan from 2014 to 2017 (NCT0294979). Patients diagnosed with Pseudomyxoma (PMP) or Peritoneal Metastasis of Colorectal Cancer (PM-CRC) were submitted to CRS and then randomized to receive low IAP (8-12 mmHg) or high IAP (18-22 mmHg) HIPEC. Hemodynamic and respiratory data were collected in eight different time-points during the whole procedure.

RESULTS

33 patients (n low = 15, n high = 18) with PM-CRC and PMP were analysed. The mean IAP in the low IAP HIPEC group was 11.4 mmHg (SD: 2.5) and 18.1 mmHg (SD: 2.5) in the high IAP HIPEC group (p«0.001). There was no difference in the hemodynamic parameters between both groups, except for the central venous pressure (CVP) that was significantly higher in the high IAP group (p = 0.006). High IAP was well tolerated in the experimental arm with no hemodynamic and ventilation instability observed during the intervention.

CONCLUSION

We conclude that high IAP at the level of 18-22 mmHg during HIPEC has no significant hemodynamic parameters difference, being feasible and safe in our study.

Current Approach to the Evaluation and Management of Abdominal Compartment Syndrome in Pediatric Patients

Abdominal compartment syndrome is an emergent condition caused by increased pressure within the abdominal compartment. It can be caused by a number of etiologies, which are associated with decreased abdominal wall compliance, increased intraluminal or intraperitoneal contents, or edema from capillary leak or fluid resuscitation. The history and physical examination are of limited utility, and the criterion standard for diagnosis is intra-abdominal pressure measurement, which is typically performed via an intravesical catheter. Management includes increasing abdominal wall compliance, evacuating gastrointestinal or intraperitoneal contents, avoiding excessive fluid resuscitation, and decompressive laparotomy in select cases.

Evaluation and Management of Abdominal Compartment Syndrome in the Emergency Department

BACKGROUND

Abdominal compartment syndrome is a potentially deadly condition that can be missed in the emergency department setting.

OBJECTIVE

The purpose of this narrative review article is to provide a summary of the background, pathophysiology, diagnosis, and management of abdominal compartment syndrome with a focus on emergency clinicians.

DISCUSSION

Abdominal compartment syndrome is caused by excessive pressure within the abdominal compartment due to diminished abdominal wall compliance, increased intraluminal contents, increased abdominal contents, or capillary leak/fluid resuscitation. History and physical examination are insufficient in isolation, and the gold standard is intra-abdominal pressure measurement. Abdominal compartment syndrome is defined as an intra-abdominal pressure >20 mm Hg with evidence of end-organ injury. Management involves increasing abdominal wall compliance (e.g., analgesia, sedation, and neuromuscular blocking agents), evacuating gastrointestinal contents (e.g., nasogastric tubes, rectal tubes, and prokinetic agents), avoiding excessive fluid resuscitation, draining intraperitoneal contents (e.g., percutaneous drain), and decompressive laparotomy in select cases. Patients are critically ill and often require admission to a critical care unit.

CONCLUSIONS

Abdominal compartment syndrome is an increasingly recognized condition with the potential for significant morbidity and mortality. It is important for clinicians to be aware of the current evidence regarding the diagnosis, management, and disposition of these patients.

Noninvasive Assessment of Intra-Abdominal Pressure Using Ultrasound-Guided Tonometry: A Proof-of-Concept Study

BACKGROUND

Intra-abdominal hypertension jeopardizes abdominal organ perfusion and venous return. Contemporary recognition of elevated intra-abdominal pressure (IAP) plays a crucial role in reducing mortality and morbidity. We evaluated ultrasound-guided tonometry in this context hypothesizing that the vertical chamber diameter of this device inversely correlates with IAP.

METHODS

IAP was increased in six 5 mmHg steps to 40 mmHg by instillation of normal saline into the peritoneal cavity of eight anesthetized pigs. Liver and renal blood flows (ultrasound transit time), intravesical, intraperitoneal, and end-inspiratory plateau pressures were recorded. For ultrasound-based assessment of IAP (ultrasound-guided tonometry), a pressure-transducing, compressible chamber was fixed at the tip of a linear ultrasound probe, and the system was applied on the abdominal wall using different predetermined levels of external pressure. At each IAP level (reference: intravesical pressure), two investigators measured the vertical diameter of this chamber.

RESULTS

All abdominal flows decreased (by 39%-58%), and end-inspiratory plateau pressure increased from 15 mbar (14-17 mbar) to 38 mbar (33-42 mbar) (median, range) with increasing IAP (all P < 0.01). Vertical chamber diameter decreased from 14.9 (14.6-15.2) mm to12.8 (12.4-13.4) mm with increasing IAP. Coefficients of variations between and within observers regarding change of the vertical tonometry chamber diameter were small (all <4%), and the results were independent of the externally applied pressure level on the ultrasound probe. Correlation of IAP and vertical pressure chamber distance was highly significant (r = -1, P = 0.0004). Ultrasound-guided tonometry could discriminate between normal (baseline) pressure and 15 mmHg, between 15 and 25 mmHg) and between 25 and 40 mmHg IAP (all P ≤ 0.18). Similar results were obtained for end-inspiratory plateau pressures.

CONCLUSIONS

In our model, values obtained by ultrasound-guided tonometry correlated significantly with IAPs. The method was able to discriminate between normal, moderately, and markedly increased IAP values.

Intra-Abdominal Hypertension Is More Common Than Previously Thought: A Prospective Study in a Mixed Medical-Surgical ICU

OBJECTIVES

To determine the prevalence of intra-abdominal hypertension in mixed medical-surgical critically ill patients using modern definitions and measurement techniques. Secondarily to determine variables associated with intra-abdominal hypertension and ICU mortality.

DESIGN

A prospective observational study.

SETTING

Single institution trauma, medical and surgical ICU in Canada.

PATIENTS

Consecutive adult patients admitted to the ICU (n = 285).

INTERVENTION

Intra-abdominal pressure measurements twice a day during admission to the ICU.

MEASUREMENTS AND MAIN RESULTS

In 285 patients who met inclusion criteria, 30% were diagnosed with intra-abdominal hypertension at admission and a further 15% developed intra-abdominal hypertension during admission. The prevalence of abdominal compartment syndrome was 3%. Obesity, sepsis, mechanical ventilation, and 24-hour fluid balance (> 3 L) were all independent predictors for intra-abdominal hypertension. Intra-abdominal hypertension occurred in 28% of nonventilated patients. Admission type (medical vs surgical vs trauma) was not a significant predictor of intra-abdominal hypertension. Overall ICU mortality was 20% and was significantly higher for patients with intra-abdominal hypertension (30%) compared with patients without intra-abdominal hypertension (11%). Intra-abdominal hypertension of any grade was an independent predictor of mortality (odds ratio, 3.33; 95% CI, 1.46-7.57).

CONCLUSIONS

Intra-abdominal hypertension is common in both surgical and nonsurgical patients in the intensive care setting and was found to be independently associated with mortality. Despite prior reports to the contrary, intra-abdominal hypertension develops in nonventilated patients and in patients who do not have intra-abdominal hypertension at admission. Intra-abdominal pressure monitoring is inexpensive, provides valuable clinical information, and there may be a role for its routine measurement in the ICU. Future work should evaluate the impact of early interventions for patients with intra-abdominal hypertension.

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.

Open Abdomen in Trauma and Critical Care

The open abdomen technique and temporary abdominal closure after damage control surgery is fast becoming the standard of care for managing intra-abdominal bleeding and infectious or ischemic processes in critically ill patients. Expansion of this technique has evolved from damage control surgery in severely injured trauma patients to use in patients with abdominal compartment syndrome due to acute pancreatitis and other disorders. Subsequent therapies after use of the open abdomen technique and temporary abdominal closure are resuscitation in the intensive care unit and planned reoperation to manage the underlying cause of bleeding, infection, or ischemia. Determining the need for this potentially lifesaving intervention and managing the wound after the open abdomen has been created are all within the realm of critical care nurses. Case studies illustrate the implementation of the open abdomen technique and patient management strategies.

Reduction of Intra-abdominal Hypertension Is Associated with Increase of Cardiac Output in Critically Ill Patients Undergoing Mechanical Ventilation

Objective: To demonstrate the relationship between intra-abdominal hypertension (IAH) and cardiac output (CO) in mechanically ventilated (MV), critically ill patients.

Material and methods: This was a single-center, prospective study performed between January and April 2016, on 30 mechanically ventilated patients (mean age 67.3 ± 11.9 years), admitted in the Intensive Care Unit (ICU) of the Emergency County Hospital of Tîrgu Mureș, Romania, who underwent measurements of intra-abdominal pressure (IAP). Patients were divided into two groups: group 1 – IAP <12 mmHg (n = 21) and group 2 – IAP >12 mmHg (n = 9). In 23 patients who survived at least 3 days post inclusion, the variation of CO and IAP between baseline and day 3 was calculated, in order to assess the variation of IAP in relation to the hemodynamic status.

Results: IAP was 8.52 ± 1.59 mmHg in group 1 and 19.88 ± 8.05 mmHg in group 2 (p <0.0001). CO was significantly higher in group 1 than in the group with IAH: 6.96 ± 2.07 mmHg (95% CI 6.01–7.9) vs. 4.57 ± 1.23 mmHg (95% CI 3.62–5.52) (p = 0.003). Linear regression demonstrated an inverse correlation between CO and IAP (r = 0.48, p = 0.007). Serial measurements of CO and IAP proved that whenever accomplished, the decrease of IAP was associated with a significant increase in CO (p = 0.02).

Conclusions: CO is significantly correlated with IAP in mechanically ventilated patients, and IAH reduction is associated with increase of CO in these critically ill cases.

Bladder pressure monitoring and CO2 gas-related adverse events during per-oral endoscopic myotomy

Per-oral endoscopic myotomy (POEM) is a minimally invasive treatment for esophageal achalasia. However, POEM has the potential risk of inducing carbon dioxide (CO₂) gas-related adverse events, such as pneumoperitoneum, pneumomediastinum, and pneumothorax. The aim of this study was to evaluate the usability of bladder pressure monitoring as an index of CO₂ gas-related pneumoperitoneum. The monitoring of bladder pressure and lung compliance and the incidence of iatrogenic pneumoperitoneum were retrospectively studied in 20 patients who underwent POEM between June 2013 and March 2015. The bladder pressure was measured using a Foley catheter. Abdominal distention was found in nine patients. The bladder pressure was significantly higher in the nine patients with the distention findings compared with patients without distention [7 (6-9) mmHg vs. 1 (0-2) mmHg; P < 0.05]; however, the decrease in dynamic lung compliance was not significantly different compared with patients without distention [- 7 (- 9.3 to - 5.1) vs. - 5 (- 10.2 to - 1.3) ml/cmH₂O; P = 0.62]. Based on postoperative changes on CT scans; the following were the observations: pneumomediastinum (55%), minor pneumothorax (5%), pleural effusion (45%), atelectasis (15%), pneumoperitoneum (85%), and subcutaneous emphysema (15%). No significant clinical status was found among the patients postoperatively. Bladder pressure monitoring might be useful for detecting pneumoperitoneum during POEM.

Effect of retension sutures on abdominal pressure after abdominal surgery

PURPOSE

To evaluate the effect of retention sutures on abdominal pressure and postoperative prognosis in abdominal surgery patients.

METHODS

This prospective cohort study included patients who were admitted to Daping Hospital from May 15, 2014 to October 11, 2014. A total of 57 patients were enrolled, including 18 patients in the "U" type retention suture group, 17 patients in the intermittent retention suture group, and 22 patients in non-retention suture group. The demographic data, clinical data and risk factors for abdominal wound dehiscence were recorded. The bladder pressure (IVP) was monitored preoperatively, intraoperatively, and four days postoperatively. Additionally, the incidence of abdominal wound dehiscence and infection 14 days after the operation was recorded.

RESULTS

During the operation, the IVP decreased and then increased; it was at its lowest 1 h after the start of the operation (5.3 mmHg ± 3.2 mmHg) and peaked after tension-reducing (8.8 mmHg ± 4.0 mmHg). The IVP values in the "U" type retention suture group and intermittent retention suture group were higher than in the non-retention suture group 4 days after operation (p < 0.005). The Visual Analogue Scale (VAS) pain scores were 3.9 ± 2.2, 3.8 ± 2.0, and 3.0 ± 1.0 in the retention suture group, intermittent retention suture group and non-retention suture group, respectively. The VAS pain scores in the "U" type tension-reducing group and intermittent tension-reducing group were higher than in the non-tension-reducing group (p < 0.005).

CONCLUSION

Although retention sutures may reduce the incidence of postoperative wound dehiscence in abdominal surgery patients, they can increase the IVP and postoperative pain.

Effects of Stomach Inflation on Cardiopulmonary Function and Survival During Hemorrhagic Shock: A Randomized, Controlled, Porcine Study

BACKGROUND

Ventilation of an unprotected airway may result in stomach inflation. The purpose of this study was to evaluate the effect of clinically realistic stomach inflation on cardiopulmonary function during hemorrhagic shock in a porcine model.

METHODS

Pigs were randomized to a sham control group (n = 9), hemorrhagic shock (35 mL kg over 15 min [n = 9]), and hemorrhagic shock combined with stomach inflation (35 mL kg over 15 min and 5 L stomach inflation [n = 10]).

RESULTS

When compared with the control group, hemorrhagic shock (n = 9) increased heart rate (103 ± 11 vs. 146 ± 37 beats min; P = 0.002) and lactate (1.4 ± 0.5 vs. 4.0 ± 1.9 mmol L; P < 0.001), and decreased mean arterial blood pressure (81.3 ± 12.8 vs. 35.4 ± 8.1 mmHg; P < 0.001) and stroke-volume index (38.1 ± 6.4 vs. 13.6 ± 4.8 mL min m; P < 0.001). Hemorrhagic shock combined with stomach inflation (n = 10) versus hemorrhagic shock only (n = 9) increased intra-abdominal pressure (27.0 ± 9.3 vs. 1.1 ± 1.0 mmHg; P < 0.001), and decreased stroke-volume index (9.9 ± 6.0 vs. 20.8 ± 8.5 mL min m; P = 0.007), and dynamic respiratory system compliance (10.8 ± 4.5 vs. 38.1 ± 6.1 mL cmH2O; P < 0.001). Before versus after stomach evacuation during hemorrhagic shock, intra-abdominal pressure decreased (27.0 ± 9.3 vs. 9.8 ± 5.4 mmHg; P = 0.042). Survival in the sham control and hemorrhagic shock group was 9 of 9, respectively, and 3 of 10 after hemorrhagic shock and stomach inflation (P < 0.001).

CONCLUSIONS

During hemorrhagic shock stomach inflation caused an abdominal compartment syndrome and thereby impaired cardiopulmonary function and aerobic metabolism, and increased mortality. Subsequent stomach evacuation partly reversed adverse stomach-inflation triggered effects.

The effect of different types of abdominal binders on intra-abdominal pressure

Objectives:

To investigate the effect of non-elastic/elastic abdominal binders on intra-vesical pressure (IVP), physiological functions, and clinical outcomes in laparotomy patients at the perioperative stage.

Methods:

This prospective study was conducted from May to October 2014 at the Trauma Surgery Department, Daping Hospital, Chongqing, China. Laparotomy patients were randomly divided into non-elastic abdominal binder group (28 patients), and elastic abdominal binder group (29 patients). Binders were applied for 14 days following the operation, or until discharge. Demographic information, Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation II (APACHE-II) scores (prior to the operation, on the first day after operation, the day IVP measurement was stopped, and one day before discharge), and outcomes were recorded. The IVP was measured before the operation to postoperative day 7.

Results:

There were no significant differences in the demographic information, outcomes, SOFA or APACHE-II scores between the 2 groups. Initial out-of-bed mobilization occurred earlier in the elastic binder group (3.2 ± 2.0 versus 5.0 ± 3.7 days, p=0.028). A greater increase in IVP was observed in the non-elastic binder group than in the elastic binder group (2.9 ± 1.1 versus 1.1 ± 0.7 mm Hg, p=0.000).

Conclusion:

Elastic binders have relatively little effect on IVP and are more helpful at promoting postoperative recovery than non-elastic binders. Therefore, elastic binders are more suitable for clinical use.

Prevalence and diagnosis rate of intra-abdominal hypertension in critically ill adult patients: A single-center cross-sectional study

PURPOSE

To investigate the prevalence and diagnosis rate of intra-abdominal hypertension (IAH) in a mixed-population intensive care unit (ICU), and to investigate the knowledge of ICU staff regarding the guidelines published by the World Society of Abdominal Compartment Syndrome (WSACS) in 2013.

METHODS

A one-day cross-sectional study based on the WSACS 2013 guidelines was conducted in the general ICU of a tertiary teaching hospital in Chongqing, China. The included patients were divided into intravesical pressure (IVP) measured group and IVP unmeasured group. The epidemiologic data were recorded, and potential IAH risk factors (RFs) were collected based on the guidelines. IVP measurements were conducted by investigators every 4 h and the result was compared to that measured by the ICU staff to evaluate the diagnosis rate. Besides, a questionnaire was used to investigate the understanding of the guidelines among ICU staff.

RESULTS

Thirty-two patients were included, 14 in the IVP measured group and 18 in the IVP unmeasured group. The prevalence of IAH during the survey was 15.63% (5/32), 35.71% (5/14) in IVP measured group. Only one case of IAH had been diagnosed by the ICU physician and the diagnosis rate was as low as 20.00%. Logistic regression analysis showed that sequential organ failure assessment (SOFA) score was an independent RF for IAH (OR: 1.532, 95% CI: 1.029-2.282, p=0.036. Fourteen doctors and 5 nurses were investigated and the response rate was 67.86%. The average scores of the doctors and nurses were 27.14±20.16 and 16.00±8.94 respectively. None of them had studied the WSACS 2013 guidelines thoroughly.

CONCLUSION

Patients with a higher SOFA score has a higher incidence of IAH. The IAH prevalence in 14 ICU patients with indwelling catheter was 35.71%. Strengthening the wide and rational use of WSACS guideline is important to improve the diagnosis of IAH.

Study of intra-abdominal hypertension prevalence and awareness level among experienced ICU medical staff

BACKGROUND

Intra-abdominal hypertension (IAH) is a disease with high morbidity and mortality among critically ill patients. The study's objectives were to explore the prevalence of IAH and physicians' awareness of the 2013 World Society of Abdominal Compartment Syndrome (WSACS) guidelines in Chinese intensive care units (ICUs).

METHODS

A cross-sectional study of four ICUs in Southwestern China was conducted from June 17 to August 2, 2014. Adult patients admitted to the ICU for more than 24 h, with bladder catheter but without obvious intravesical pressure (IVP) measurement contraindications, were recruited. Intensivists with more than 5 years of ICU working experience were also recruited. Epidemiological information, potential IAH risk factors, IVP measurements and questionnaire results were recorded.

RESULTS

Forty-one patients were selected. Fifteen (36.59 %) had IVP ≥ 12 mmHg. SOFA (Sequential Organ Failure Assessment) hepatic and neurological sub-scores were utilized as independent predictors for IAH via logistic backward analysis. Thirty-seven intensivists participated in the survey (response rate: 80.43 %). The average score of each center was less than 35 points. All physicians believed the IAH prevalence in their departments was no more than 20.00 %. A significant negative correlation was observed between the intensivists' awareness of the 2013 WSACS guidelines and the IAH prevalence in each center (r = -0.975, P = 0.025).

CONCLUSIONS

The prevalence and independent predictors of IAH among the surveyed population are similar to the reports in the literature. Intensivists generally have a low awareness of the 2013 WSACS guidelines. A systematic guideline training program is vital for improving the efficiency of the diagnosis and treatment of IAH.

Intra-abdominal pressure correlates with extracellular water content

Background

Secondary increase in intra-abdominal pressure (IAP) may result from extra-abdominal pathology, such as massive fluid resuscitation, capillary leak or sepsis. All these conditions increase the extravascular water content. The aim of this study was to analyze the relationship between IAP and body water volume.

Material and Methods

Adult patients treated for sepsis or septic shock with acute kidney injury (AKI) and patients undergoing elective pharyngolaryngeal or orthopedic surgery were enrolled. IAP was measured in the urinary bladder. Total body water (TBW), extracellular water content (ECW) and volume excess (VE) were measured by whole body bioimpedance. Among critically ill patients, all parameters were analyzed over three consecutive days, and parameters were evaluated perioperatively in surgical patients.

Results

One hundred twenty patients were studied. Taken together, the correlations between IAP and VE, TBW, and ECW were measured at 408 time points. In all participants, IAP strongly correlated with ECW and VE. In critically ill patients, IAP correlated with ECW and VE. In surgical patients, IAP correlated with ECW and TBW. IAP strongly correlated with ECW and VE in the mixed population. IAP also correlated with VE in critically ill patients. ROC curve analysis showed that ECW and VE might be discriminative parameters of risk for increased IAP.

Conclusion

IAP strongly correlates with ECW.

Pre-eclampsia renamed and reframed: Intra-abdominal hypertension in pregnancy

This hypothesis proposes pre-eclampsia is caused by intra-abdominal hypertension in pregnancy. Sustained or increasing intra-abdominal pressure ⩾12mmHg causes impaired venous return to the heart, systemic vascular resistance, ischemia reperfusion injury, intestinal permeability, translocation of lipopolysaccharide endotoxin to the liver, cytotoxic immune response, systemic inflammatory response, pressure transmission to thoracic and intra-cranial compartments, and multi-organ dysfunction. This hypothesis is predicated on Pascal's law, evidence founded in the intra-abdominal hypertension literature, and the adapted equation ΔIAP-P=ΔIAVF/Cab, where ΔIAP-P=change in intra-abdominal pressure in pregnancy, ΔIAVF=change in intra-abdominal vector force (volume and force direction) and Cab=abdominal compliance. Factors causing increased intra-abdominal pressure in pregnancy include: progressive uterine expansion, obstetrical factors that increase intra-uterine volume excessively or acutely, maternal anthropometric measurements that affect intra-abdominal pressure thresholds, maternal postures that increase abdominal force direction, abdominal compliance that is decreased, diminished with advancing gestation, or has reached maximum expansion, habitation at high altitude, and rapid drops in barometric pressure. We postulate that the threshold for lipopolysaccharide translocation depends on the magnitude of intra-abdominal pressure, the intestinal microbiome complex, and the degree of intestinal permeability. We advance that delivery cures pre-eclampsia through the mechanism of abdominal decompression.

Drainage of pleural effusion in mechanically ventilated patients: time to measure chest wall compliance?

PURPOSE

Pleural effusion (PE) is commonly encountered in mechanically ventilated, critically ill patients and is generally addressed with evacuation or by fluid displacement using increased airway pressure (P(AW)). However, except when massive or infected, clear evidence is lacking to guide its management. The aim of this study was to investigate the effect of recruitment maneuvers and drainage of unilateral PE on respiratory mechanics, gas exchange, and lung volume.

MATERIALS AND METHODS

Fifteen critically ill and mechanically ventilated patients with unilateral PE were enrolled. A 3-step protocol (baseline, recruitment, and effusion drainage) was applied to patients with more than 400 mL of PE, as estimated by chest ultrasound. Predefined subgroup analysis compared patients with normal vs reduced chest wall compliance (C(CW)). Esophageal and P(AW)s, respiratory system, lung and C(CW)s, arterial blood gases, and end-expiratory lung volumes were recorded.

RESULTS

In the whole case mix, neither recruitment nor drainage improved gas exchange, lung volume, or tidal mechanics. When C(CW) was normal, recruitment improved lung compliance (81.9 [64.8-104.1] vs 103.7 [91.5-111.7] mL/cm H2O, P < .05), whereas drainage had no significant effect on total respiratory system mechanics or gas exchange, although it measurably increased lung volume (1717 vs 2150 mL, P < .05). In the setting of reduced C(CW), however, recruitment had no significant effect on total respiratory system mechanics or gas exchange, whereas pleural drainage improved respiratory system and C(CW)s as well as lung volume (42.7 [38.9-50.0] vs 47.0 [43.8-63.3], P < .05 and 97.4 [89.3-97.9] vs 126.7 [92.3-153.8] mL/cm H2O, P < .05 and 1580 vs 1750 mL, P < .05, respectively).

CONCLUSIONS

Drainage of a moderate-sized effusion should not be routinely performed in unselected population of critically ill patients. We suggest that measurement of C(CW) may help in the decision-making process.