Intra-abdominal hypertension: evolving concepts

Risk factors for premature rupture of membranes in pregnant women: a systematic review and meta-analysis

OBJECTIVE

To identify risk factors for premature rupture of membranes (PROM) in pregnant women.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Web of Science, PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang Database, Chinese Scientific Journal Database (VIP) and China Biology Medicine Disc were searched from inception to October 2022.

ELIGIBILITY CRITERIA

Cross-sectional, case-control and cohort studies published in English or Chinese that reported the risk factors for PROM were eligible for inclusion.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted the data and evaluated the risk of bias using the Newcastle-Ottawa Scale and American Agency for Healthcare Research and Quality tools. Analyses were performed using RevMan 5.4 software, and heterogeneity was assessed using χ2 tests and I2 statistics. The sensitivity analyses included a methodological transition between fixed-effect and random-effect models and the systematic stepwise exclusion of studies.

RESULTS

A total of 21 studies involving 18 174 participants with 18 risk factors were included. The significant risk factors were low Body Mass Index (BMI) (OR 2.18, 95% CI 1.32 to 3.61), interpregnancy interval (IPI) <2 years (OR 2.99, 95% CI 1.98 to 4.50), previous abortion (OR 2.35, 95% CI 1.76 to 3.14), previous preterm birth (OR 5.72, 95% CI 3.44 to 9.50), prior PROM (OR 3.95, 95% CI 2.48 to 6.28), history of caesarean section (OR 3.06, 95% CI 1.72 to 5.43), gestational hypertension (OR 3.84, 95% CI 2.36 to 6.24), gestational diabetes mellitus (GDM) (OR 2.16, 95% CI 1.44 to 3.23), abnormal vaginal discharge (OR 2.17, 95% CI 1.45 to 3.27), reproductive tract infection (OR 2.16, 95% CI 1.70 to 2.75), malpresentation (OR 2.26, 95% CI 1.78 to 2.85) and increased abdominal pressure (OR 1.45, 95% CI 1.07 to 1.97). The sensitivity analysis showed that the pooled estimates were stable.

CONCLUSIONS

This meta-analysis indicated that low BMI, IPI <2 years, previous abortion, previous preterm birth, prior PROM, history of caesarean section, gestational hypertension, GDM, abnormal vaginal discharge, reproductive tract infection, malpresentation and increased abdominal pressure might be associated with a greater risk of PROM. Associations between smoking status, short cervical length, fine particulate matter (PM2.5) and PROM require further investigation.

PROSPERO REGISTRATION NUMBER

CRD42022381485.

A Case Report of Pseudotumor Cerebri Syndrome with a Huge Retroperitoneal Cyst

Background: Aside from primary pseudotumor cerebri syndrome (PTCS) with an unknown etiology (i.e., idiopathic intracranial hypertension), which typically occurs in association with obesity, several conditions including cerebral venous abnormalities, drug use, and hormonal imbalance may be a secondary cause of PTCS. However, a focal space-occupying lesion outside of the brain as a cause of PTCS has rarely been reported. Case Presentation: A previously healthy 34-year-old man presented with blurred vision for three weeks. The patient had a three-month preceding history of worsening headache. On admission, he was hypertensive (160/90 mmHg) and underweight with a body mass index of 18.4 kg/m2. Fundus examination documented papilledema in both eyes. Neurological examination was unremarkable except for mild nuchal rigidity, and results of routine serologic testing were normal. Gadolinium-enhanced brain magnetic resonance imaging revealed bilateral posterior scleral flattening, suggesting intracranial hypertension. There was no other abnormal brain parenchymal lesion or meningeal enhancement. Cerebrospinal fluid (CSF) assay showed a markedly increased opening pressure (30.0 cmH2O) with normal CSF composition. A tentative diagnosis of PTCS was made based on ophthalmological, neuroradiological, and laboratory findings. During differential diagnosis, abdomen computed tomography demonstrated a huge benign cystic lesion (14.7 × 10.6 × 16.4 cm) in the right retroperitoneal space, which originated from the mesentery and resulted in hydronephrosis and renovascular hypertension due to external compression of the right kidney. Other evaluations were unremarkable. After successful surgical removal of the cyst, clinical symptoms such as headache, blurred vision, and papilledema on fundus examination were markedly improved, and blood pressure was normalized during the three-month follow-up period. Conclusions: A large retroperitoneal cyst that can increase intra-abdominal pressure could be a rare cause of PTCS. Therefore, meticulous evaluation is warranted for patients with PTCS, especially those without known risk factors.

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.

Relationship Between Intra-Abdominal pressure and microaspiration of gastric contents in critically ill mechanically ventilated patients

The relationship between increased intra-abdominal pressure (IAP) and microaspiration of oro-gastric content in mechanically-ventilated patients has not yet been established. Microaspiration is proposed as one of the causes of ventilator-associated pneumonia (VAP). We aimed to investigate whether mechanically-ventilated patients with increased IAP present evidence of lung microaspiration by assessing pepsin levels in bronchial secretions and evaluated the relationship between pepsin and VAP. 68 mechanically-ventilated patients and 10 control subjects were recruited from an academic ICU in Greece. IAP, pH, pepsin and total protein levels, in bronchial secretions, were assessed within 14 days. Patients underwent assessment for timely VAP diagnosis based on clinical, radiological and laboratory criteria. Pepsin and total protein levels were significantly elevated in patients compared to controls. Pepsin values correlated significantly with IAP (r = 0.61, ***p < 0.001). Multivariate regression analysis showed that IAP was an independent risk factor for increased pepsin values in bronchial secretions [OR95%CI 1.463(1.061-1.620), *p = 0.014]. Pepsin values were higher in patients with VAP, while IAP was independently associated with VAP. There was an indication towards increased VAP in patients with increased pepsin. In conclusion, our results show that pepsin in bronchial secretions may be elevated when IAP is increased, indicating microaspiration and potentially VAP.

Intra-Abdominal Hypertension Contributes to the Development of Ventilator-Associated Pneumonia from Intestinal Bacteria

Introduction

Ventilator-associated pneumonia (VAP) is an ICU (intensive care unit)-acquired pulmonary parenchymal infection that is complicated by mechanical ventilation and is associated with high morbidity and mortality. Klebsiella pneumoniae (KPN) is known to asymptomatically colonize the gastrointestinal tract and may increase the incidence of corresponding VAP. Our study aims were to investigate the exact origin of the carbapenem-resistant Klebsiella pneumoniae (CRKP) causing VAP in our patient.

Methods

Various environmental samples, including the patient's anal swab, were collected in order to find the source of the bacteria. Minimum inhibitory concentrations (MICs) for antimicrobial agents were determined according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI); resistant genes were detected by using PCR and sequencing; clone relationships were analyzed by using multilocus-sequence typing (MLST) and pulsed field gel electrophoresis (PFGE). The IAP values were obtained via urinary catheter.

Results

One CRKP strain was detected in the patient's anal swab; this strain was confirmed with the same gene type as the strain isolated from the sputum. We found that the patient's intra-abdominal pressure (IAP) was 29.41, 27.06, 24.12, and 22.66 mmHg; the IAP was either equal to or above 12 mmHg, on the operation day and the following three days. Intra-abdominal hypertension (IAH) occurred during the patient's hospitalization and was considered to be caused by the surgical procedure. Meanwhile, we found that there was a correlation between IAH and the detection of CRKP in the sputum. The findings suggested that his VAP was caused by intestinal colonial KPN, and not from the environment.

Discussion

Our research illustrated that the ST11 KPC-2-producing strain colonized the intestinal tract and caused the development of VAP when the IAP was elevated. Routine screening for the intestinal carriage of CRKP, among patients in ICUs, can limit and prevent current and future outbreaks.

Risk factors for abdominal compartment syndrome in trauma – A review

" Background and Aim: Abdominal compartment syndrome is a life-threatening complication that can occur in trauma patients and greatly increase their mortality. Although there is a better scientific understanding of the general phenomena involved in the pathogenesis of this complication, the particular risk factors and their implications in the trauma patient population are yet to be deciphered. Methods: The authors conducted research through 3 electronic databases (PubMed, Scopus, and ScienceDirect) using the following search formula: “(ACS OR abdominal compartment syndrome) AND (*trauma*) AND (risk factor)”. Subsequently, additional search formulas were used, including the risk factors taken into consideration (i.e. “shock”, “hypotension”, “acidosis”, “base deficit”, ”coagulopathy”, “retroperitoneal hematoma”, “HOB elevation”, “fluid resuscitation”, “damage control laparotomy”). Results: Throughout the 41 articles analyzed in this paper, 7 risk factors transcended and were further discussed: head of bed elevation/patient positioning, fluid resuscitation, the “lethal triad” of acidosis hypothermia and coagulopathy, Damage Control Laparotomy, shock/hypotension, retroperitoneal hematoma and demographics (age, gender, and race). Conclusions: To summarize, many potential risk factors were evaluated for the envisagement of the present paper, but the ones that prevailed the most were excessive fluid resuscitation, shock/hypotension, retroperitoneal hematomas, and the lethal triad. Consistent with other studies, no connection was found between age, gender, or race and the development of ACS. Further studies should focus more on the likely involvement of damage control laparotomy and patient positioning, as well as hypocalcemia, in the unfolding of ACS in trauma patients"

The prevalence, incidence and mortality associated with intra-abdominal hypertension among patients in intensive care units of a low-income country: a cohort study

Background: Intra-abdominal hypertension (IAH) is sustained increase in intra-abdominal pressure (IAP) ≥12 mmHg in adults and ≥10 mmHg in children. IAH has been noted to be associated with increased morbidity and mortality among critically ill patients. Measurement of IAP is common among at risk patients in the developed world. However, it has not received due attention in the majority of intensive care units (ICUs) in low-income countries, Uganda being one of these. This is evidenced by paucity of data and lack of protocols from the Ugandan Ministry of Health. This multi-center study was thus conducted to assess the prevalence, incidence and mortality associated with IAH among patients admitted to Ugandan ICUs.Methods:A multi-center prospective cohort study was conducted from September 2017 to February 2018 at three ICUs in Uganda. We consecutively enrolled 126 patients into the study. IAP was measured using the Harrahil manometer technique. Categorical variables were analyzed using the Chi square test and continuous variables analyzed using the t-test and Man Whitney test. The prevalence and incidence were determined using proportions and mortality was determined using survival analysis.Results:The median age was 33 years (26-48.5) for the patients without IAH and 42 years (29-55) for those with IAH. The majority of the patients were male and 9.6% of the patients were below 18 years. The prevalence of IAH was 62.7 (CI 54.1-71.3), whereas the 24 hour and 72 hour incidence of IAH was 9.3% (CI 1.3-17.2) and 14.3 % (CI 4.1-24.4), respectively.  Mortality was higher in patients with IAH compared to those without (p-value 0.003 and 0.028, mean and maximum IAP, respectively). Conclusion:We found a high prevalence and incidence of IAH among critically ill patients, associated with a high mortality. Routine screening for IAH can preempt management strategies to mitigate this.

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.

Abdominal compartment syndrome: Often overlooked conditions in medical intensive care units

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome are well recognized entities among surgical patients. Nevertheless, a number of prospective and retrospective observational studies have shown that IAH is prevalent in about half of the critically ill patients in the medical intensive care units (ICU) and has been widely recognized as an independent risk factor for mortality. It is alarming to note that many members of the critical care team in medical ICU are not aware of the consequences of untreated IAH and the delay in making the diagnosis leads to increased morbidity and mortality. Frequently it is underdiagnosed and undertreated in this patient population. Elevated intra-abdominal pressure decreases the blood flow to the kidneys and other abdominal viscera and also results in reduced cardiac output and difficulties in ventilating the patient because of increased intrathoracic pressure. When intraabdominal hypertension is not promptly recognized and treated, it leads to abdominal compartment syndrome, multiorgan dysfunction syndrome and death. Large volume fluid resuscitation is very common in medical ICU patients presenting with sepsis, shock and other inflammatory conditions like pancreatitis and it is one of the major risk factors for the development of intra-abdominal hypertension. This article presents an overview of the epidemiology, definitions, risk factors, pathophysiology and management of IAH and abdominal compartment syndrome in critically ill medical ICU patients.

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.

Effect of intra-abdominal hypertension on plasma exogenous creatinine clearance in conscious and anesthetized dogs

OBJECTIVE

To evaluate the effect of intra-abdominal pressure (IAP) on plasma exogenous creatinine clearance in both conscious and anesthetized dog models using a balloon technique to generate intra-abdominal hypertension.

DESIGN

Prospective, cross-over, experimental study.

SETTING

University-based small animal research facility.

ANIMALS

Six healthy male Beagle dogs.

INTERVENTIONS

A balloon device comprising a Foley urinary catheter and latex balloon was placed in the intra-abdominal cavity. Plasma exogenous creatinine clearance was compared after intravenous administration of exogenous creatinine solution at 80 mg/kg under 4 different treatment conditions as follows: control and IAP levels of 25 mm Hg in conscious dogs and control and IAP levels of 25 mm Hg in anesthetized dogs (CC, C25, AC, and A25, respectively). Samples were obtained before (T0) and 10, 20, 30, 60, 90, 120, 240, 360, 480, and 600 min after administration of creatinine in all treatment groups.

MEASUREMENTS AND MAIN RESULTS

There were no significant differences in plasma creatinine concentration for CC, AC, and C25 during the treatment period. However, in the A25 treatment condition, the plasma creatinine concentration increased significantly at 10, 20, 30, 60, 90, and 120 min after administration of creatinine (P < 0.05). Plasma creatinine clearances were 5.0 ± 0.5, 4.7 ± 1.2, 5.5 ± 0.9, and 2.5 ± 0.5 mL/kg/min for 600 min (CC, AC, C25, and A25, respectively). In the A25 treatment condition, the plasma exogenous creatinine clearance decreased significantly to 50%, 47%, and 55% of that under control conditions (CC, AC, and C25, respectively). After decompression of the abdomen, plasma creatinine concentrations declined rapidly and returned to basal concentrations.

CONCLUSIONS

Intra-abdominal hypertension under general anesthesia could cause renal hypoperfusion. Timely decompression may improve the outcome of acutely increased IAP when surgery and/or general anesthesia is required in canine patients.

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.

Computed tomographic features of intra-abdominal hypertension in three dogs

OBJECTIVE

To describe computed tomographic (CT) features of intra-abdominal hypertension (IAH) in 3 dogs with abdominal distension.

CASE SUMMARY

Three dogs with anorexia, distended abdomen, or labored breathing were presented for CT imaging. All 3 dogs were premedicated with IV butorphanol (0.2 mg/kg). A Foley urinary catheter was aseptically placed and the transvesical technique was used to obtain intra-abdominal pressure (IAP). The IAP measurements were obtained with the dogs in a standing position after a stabilization period of 5 minutes. The mean IAP values for each of the 3 dogs were 26.0, 12.0, and 13.0 mm Hg. Anesthesia was induced with IV propofol (2.0-4.0 mg/kg, to effect) in all 3 dogs and maintained with sevoflurane in 2 dogs. Compression of the caudal vena cava and elevation of the diaphragm were observed in all 3 dogs, whereas renal compression and the extension of peritoneal fluid to the vaginal canal and cavity were seen in the dog with the highest IAP.

NEW OR UNIQUE INFORMATION PROVIDED

Compression of the caudal vena cava, direct renal compression, and the extension of peritoneal fluid into the vaginal canal and vaginal cavity are consistent with a diagnosis of IAH. Measurement of IAP and detection of these CT features should alert clinicians to the possible presence of IAH in veterinary patients.

Is intra-abdominal hypertension a risk factor for ventilator-associated pneumonia?

In the last years, there has been a significant amount of research about the impact of intra-abdominal hypertension (IAH) on the outcomes of critical care patients. IAH is increasingly recognized as potential complication in intensive care unit (ICU) patients. IAH affects all body systems, most notably the cardiac, respiratory, renal, and neurologic systems. IAH affects blood flow to various organs and plays a significant role in the prognosis of the patients. Recognition of IAH, its risk factors and clinical signs can reduce the morbidity and mortality associated. Moreover, knowledge of the pathophysiology may help rationalize the therapeutic approach. On the other hand, ICU patients present frequently ventilator- associated respiratory infections. Ventilator-associated pneumonia (VAP) is the most common healthcare-associated infection (HAI) in adult critical care units. It is associated with increased ICU stay, patient ventilator days and mortality. This paper reviews the relationship between IAH and VAP. Despite animal experimentation and physiological studies on humans, in favor of the impact of IAH to VAP, there is no definitive clinical data that IAH is associated with VAP. Microaspirations form the gastrointestinal track is a pathophysiological mechanism for VAP. This review provides data suggesting that under IAH conditions bacterial translocation might be an additional responsible mechanism for VAP in those patients that merits further investigation in the future.

The Pathogenesis of Nonocclusive Mesenteric Ischemia: Implications for Research and Clinical Practice

Nonocclusive mesenteric ischemia (NOMI) is a condition that can encompass ischemia, inflammation, and infarction of the intestinal wall. In contrast to most patients with acute mesenteric ischemia, NOMI is distinguished by patent arteries and veins. The clinical presentation of NOMI is often insidious and nonspecific, resulting in a delayed diagnosis. Patients most at risk are those with severe acute and critical disease, including major surgery and trauma. Nonocclusive mesenteric ischemia is part of a spectrum, from mild, asymptomatic, and an unexpected finding on CT scanning, through to those exhibiting abdominal distension and peritonitis. Severe NOMI is associated with a significant mortality rate. This review of NOMI pathophysiology was conducted to document current concepts and evidence, to examine the implications for diagnosis and treatment, and to identify gaps in knowledge that might direct future research. The key pathologic mechanisms involved in the genesis of NOMI represent an exaggerated normal physiological response to maintain perfusion of vital organs at the expense of mesenteric perfusion. A supply-demand mismatch develops in the intestine due to the development of persistent mesenteric vasoconstriction resulting in reduced blood flow and oxygen delivery to the intestine, particularly to the vulnerable superficial mucosa. This mismatch can be exacerbated by raised intra-abdominal pressure, enteral nutrition, and the use of certain vasoactive drugs, ultimately resulting in the development of intestinal ischemia. Strategies for prevention, early detection, and treatment are urgently needed.

The gastro-renal effects of intra-abdominal hypertension: Implications for critical care nurses

Intra-abdominal hypertension is classified as either primary or secondary - primary occurs due to intra-abdominal or retro-peritoneal pathophysiology, whereas secondary results in alterations in capillary fluid dynamics due to factors, such as massive fluid resuscitation and generalised inflammation. The renal and gastro-intestinal effects occur early in the progression of intra-abdominal hypertension, and may lead to poor patient outcomes if not identified. As a direct response to intra-abdominal hypertension, renal function is reduced with remarkable impairment from pressures of around 10 mmHg, oliguria developing at 15 mmHg and anuria developing at 30 mmHg. Intestinal micro-circulation is significantly reduced by up to 50% with intra-abdominal pressures as low as 15 mmHg. Mucosal and submucosal tissue hypo-perfusion causes considerable damage to the intestinal cells, potentially resulting in bacterial translocation, endotoxin release, sepsis and multiple organ failure. The critical care nurse plays an important role in the early identification of intra-abdominal hypertension however, without this essential knowledge base and comprehension of intra-abdominal hypertension, clinical signs and symptoms may go unnoticed or be misinterpreted as signs of other critical illnesses.

Intra-Abdominal Hypertension is a Risk Factor for Increased VAP Incidence: A Prospective Cohort Study in the ICU of a Tertiary Hospital

BACKGROUND

Ventilator-associated pneumonia (VAP) might be increased in cases with intra-abdominal hypertension (IAH). However, despite animal experimentation and physiological studies on humans in favor of this hypothesis, there is no definitive clinical data that IAH is associated with VAP. We therefore aimed to study whether IAH is a risk factor for increased incidence of VAP in critical care patients. This 1-center prospective observational cohort study was conducted in the intensive care unit of the University Hospital of Larissa, Greece, during 2013 to 2015. Consecutive patients were recruited if they presented risk factors for IAH at admission and were evaluated systematically for IAH and VAP for a 28-day period.

RESULTS

Forty-five (36.6%) of 123 patients presented IAH and 45 (36.6%) presented VAP; 24 patients presented VAP following IAH. Cox regression analysis showed that VAP was independently associated with IAH (1.06 [1.01-1.11]; P = .053), while there was an indication for an independent association between VAP and abdominal surgery (1.62 [0.87-3.03]; P = .11] and chronic obstructive pulmonary disease (1.79 [0.96-3.37]; P = .06).

CONCLUSIONS

Intra-abdominal hypertension is an independent risk factor for increased VAP incidence in critically ill patients who present risk factors for IAH at admission to the ICU.

A novel balloon technique to induce intra-abdominal hypertension and its effects on cardiovascular parameters in a conscious dog model

OBJECTIVE

To evaluate a new balloon technique to induce intra-abdominal hypertension (IAH) and abdominal compartment syndrome in a conscious dog model, and to evaluate the effect of intra-abdominal pressure (IAP) on cardiovascular, respiratory, and arterial blood gas values in conscious dogs with IAH.

DESIGN

Prospective, experimental study.

SETTING

University-based small animal research facility.

ANIMALS

Six healthy Beagle dogs, 4 males, and 2 females.

INTERVENTIONS

A new balloon device designed for this study using a Foley urethral catheter and latex balloon was placed in the abdominal cavity. Consecutive measurements of IAP were made by measuring the intravesicular pressure. The abdomen was inflated with air to IAPs of 10, 15, 20, and 25 mm Hg. Heart rate, respiratory rate, systolic arterial blood pressure, and arterial blood gases were evaluated at baseline and at 15, 30, 45, 60, 120, 240, and 300 minutes after IAP increase.

MEASUREMENTS AND MAIN RESULTS

The air insufflated into the intra-abdominal balloon device significantly increased the IAP and led to sustained IAH. The respiratory rate increased significantly (P < 0.05) when IAP was increased to 15, 20, and 25 mm Hg. Although heart rate, systolic arterial blood pressure, PaO₂ , and PaCO₂ did not show statistically significant differences between baseline and posttreatment values over time, the dogs with increased IAP showed a distended abdomen and apparent discomfort, and 4/6 (67%) vomited. After measurement of IAP, air was removed. There were no adverse effects noted after removal of the balloon device.

CONCLUSION

The balloon device was successfully insufflated and led to sustained IAH in conscious dogs. This balloon technique does not require general anesthesia for instillation or removal of gas after installment. An acute IAP increase in normal conscious dogs induced discomfort, vomiting, and increased respiratory effort.

The cardio-respiratory effects of intra-abdominal hypertension: Considerations for critical care nursing practice

Intra-abdominal hypertension can be classified as either primary or secondary. Primary intra-abdominal hypertension is often associated through trauma or diseases of the abdominopelvic region such as pancreatitis or abdominal surgery, while secondary intra-abdominal hypertension is the result of extra-abdominal causes such as sepsis or burns. The critically ill patient offers some challenges in monitoring in particular secondary intra-abdominal hypertension because of the effects of fluid resuscitation, the use of inotropes and positive pressure ventilation. Recent work suggests that intensive care unit nurses are often unaware of the secondary effects of intra-abdominal pressure and therefore this is not monitored effectively. Therefore being aware of the cardio-respiratory effects may alert theintensive care nurse nurse to the development of intra-abdominal hypertension. The aim of this paper is to discuss the pathophysiology associated with the cardio-respiratory effects seen with intra-abdominal hypertension in the critically ill. In particular it will discuss how intra-abdominal hypertension can inadvertently be overlooked because of the low flow states that it produces which could be misconstrued as something else. It will also discuss how intra-abdominal hypertension impedes ventilation and respiratory mechanics which can often result in a non-cardiogenic pulmonary oedema. To close, the paper will offer some implications for critical care nursing practice.

Intra-Abdominal Hypertension Causes Bacterial Growth in Lungs: An Animal Study

To study the effect of intra-abdominal hypertension (IAH) on the frequency of pneumonia with an experimental study, thirteen Sprague-Dawley rats were included. Eight out of thirteen animals were randomly assigned to receive 10 ml of benzalkonium chloride 0.2% (megacolon group) and five animals received 10 ml NaCl 0.9% (controls). Animals were anaesthetized by intramuscular delivery of ketamine. The incidence of positivity for bacteria lung tissue cultures and mesenteric lymph node cultures was assessed at the 21st day after animals' sacrification, or before in case of death. All megacolon group animals presented progressive increase of the abdomen and increased IAP (≥10 mmHg) whereas the frequency of their evacuations was almost eliminated. Controls presented normal evacuations, no sign of abdominal distention, and normal IAP. In megacolon group animals, there was evidence of significant amount of bacteria in lung cultures. In contrast, no bacteria were found in control animals.

Mechanical Intestinal Obstruction in a Porcine Model: Effects of Intra-Abdominal Hypertension. A Preliminary Study

INTRODUCTION

Mechanical intestinal obstruction is a disorder associated with intra-abdominal hypertension and abdominal compartment syndrome. As the large intestine intraluminal and intra-abdominal pressures are increased, so the patient's risk for intestinal ischaemia. Previous studies have focused on hypoperfusion and bacterial translocation without considering the concomitant effect of intra-abdominal hypertension. The objective of this study was to design and evaluate a mechanical intestinal obstruction model in pigs similar to the human pathophysiology.

MATERIALS AND METHODS

Fifteen pigs were divided into three groups: a control group (n = 5) and two groups of 5 pigs with intra-abdominal hypertension induced by mechanical intestinal obstruction. The intra-abdominal pressures of 20 mmHg were maintained for 2 and 5 hours respectively. Hemodynamic, respiratory and gastric intramucosal pH values, as well as blood tests were recorded every 30 min.

RESULTS

Significant differences between the control and mechanical intestinal obstruction groups were noted. The mean arterial pressure, cardiac index, dynamic pulmonary compliance and abdominal perfusion pressure decreased. The systemic vascular resistance index, central venous pressure, pulse pressure variation, airway resistance and lactate increased within 2 hours from starting intra-abdominal hypertension (p<0.05). In addition, we observed increased values for the peak and plateau airway pressures, and low values of gastric intramucosal pH in the mechanical intestinal obstruction groups that were significant after 3 hours.

CONCLUSION

The mechanical intestinal obstruction model appears to adequately simulate the pathophysiology of intestinal obstruction that occurs in humans. Monitoring abdominal perfusion pressure, dynamic pulmonary compliance, gastric intramucosal pH and lactate values may provide insight in predicting the effects on endorgan function in patients with mechanical intestinal obstruction.

Intra-abdominal pressure in third trimester pregnancy complicated by acute pancreatitis: an observational study

BACKGROUND

It is known that intra-abdominal hypertension has high morbidity in acute pancreatitis and has detrimental effects on patients. For third trimester pregnancy complicated by acute pancreatitis, the intra-abdominal pressure may have its own characteristic. This article will discuss this clinical scenario.

METHODS

This observational study in a cohort group was performed in the surgical intensive care unit of a tertiary hospital. Medical records were reviewed from each acute pancreatitis exactly in third trimester pregnancy. The main statistical methods were Mann-Whitney U test and bivariate Pearson correlation analysis.

RESULTS

During the study interval, there were totally 17 pregnancies complicated by acute pancreatitis in the third trimester. All cases with moderate or severe acute pancreatitis had intra-abdominal hypertension of mean value of 16.7 mm Hg (range, 12.9-22.0 mm Hg). The intra-abdominal pressure had significant correlation with APACHE II score (r = 0.7456, p = 0.0006), while a negative correlation was showed with the umbilical artery pH value and with 1-min Apgar score (r = -0.8232, p = 0.0005; r = -0.7465, p = 0.0034; respectively). The intra-abdominal pressure of those with live infants was lower than that of those with dead ones (13.78 ± 2.554 vs. 19.84 ± 1.695, p = 0.0019).

CONCLUSIONS

The incidence of intra-abdominal hypertension seems higher in moderate or severe acute pancreatitis in third trimester pregnancy than the non-pregnant cases but there's no significance in this study. Acute elevated intra-abdominal pressure accounts for great association with mother's serious scenario and fetal mortality.

Damage Control and the Open Abdomen: Challenges for the Nonsurgical Intensivist

BACKGROUND

As strategies in acute care surgery focus on damage control to restore physiology, intensivists spanning all disciplines care for an increasing number of patients requiring massive transfusion, temporary abdominal closures, and their sequelae.

OBJECTIVE

To equip the nonsurgical intensivist with evidence-based management principles for patients with an open abdomen after damage control surgery.

DATA SOURCE

Search of PubMed database and manual review of bibliographies from selected articles.

DATA SYNTHESIS AND CONCLUSIONS

Temporary abdominal closure improves outcomes in patients with abdominal compartment syndrome, hemorrhagic shock, and intra-abdominal sepsis but creates new challenges with electrolyte derangement, hypovolemia, malnutrition, enteric fistulas, and loss of abdominal wall domain. Intensive care of such patients mandates attention to resuscitation, sepsis control, and expedient abdominal closure.

Does Diastasis Width Influence the Variation of the Intra-Abdominal Pressure After Correction of Rectus Diastasis?

BACKGROUND

It has been demonstrated that there is an increase of intra-abdominal pressure (IAP) after correction of rectus diastasis.

OBJECTIVE

To evaluate the correlation between the diastasis width and IAP variation after the plication of the anterior rectus sheath.

METHODS

Seventeen patients met the inclusion criteria and were selected. The diastasis width was measured at three levels: 3 cm above the umbilicus, 2 cm above the umbilicus, and 2 cm below the umbilicus. Rectus sheath plication was performed in two layers: the first layer with separate stitches, and the second with continuous suture. The IAP was measured at two stages: before and after the correction of rectus diastasis. The distance between the iliac spines (IS) and that between the xiphoid process and pubic symphysis (XP) were measured. The abdominal surface index (ASI) was calculated using the formula: ASI = (IS × XP)/2. This index was used to determine the individual abdominal surface. The relative diastasis coefficient (RDC) was calculated using the formula: RDC = diastasis/ASI. These measurements were correlated to the IAP variation. The results of the IAP measurements obtained in each stage and the RDC values were compared, using the Pearson's linear correlation coefficient.

RESULTS

There was no statistically significant correlation between the IAP variation and the RDC values at the three levels studied.

CONCLUSIONS

The diastasis width does not interfere with the increase of the IAP when a plication of the anterior aponeurosis is performed.

LEVEL OF EVIDENCE

3 Diagnostic.

Successful Rescue of an Adult With Refractory Anaphylactic Shock and Abdominal Compartment Syndrome With Venoarterial Extracorporeal Membrane Oxygenation and Bedside Laparotomy

The incidence of life-threatening anaphylactic reactions related to anesthesia is approximately 1 in 6000 anesthetics administered, and is associated with mortality as high as 5%. In such cases the use of extracorporeal membrane oxygenation (ECMO) in the setting of refractory shock following anaphylaxis may be life saving. Abdominal compartment syndrome (ACS) itself and in this case complicating ECMO support, is a potentially devastating complication of high-volume resuscitation. Decompressive laparotomy is the treatment of choice for ACS. We present a patient treated with venoarterial ECMO for refractory shock following anaphylaxis who developed ACS that was successfully treated with urgent decompressive laparotomy performed in the intensive care unit. This case report highlights the role of abdominal compartment syndrome as a rare but potentially fatal cause of low circuit flow in ECMO-supported patients and proposes a stepwise approach to decision making in this setting. Urgent decompressive laparotomy is potentially lifesaving in this circumstance, and should be urgently considered once other causes of low ECMO flow have been excluded.

Measurement of intra-abdominal pressure in dogs and cats

OBJECTIVE

To review and summarize the human and veterinary literature on intra-abdominal pressure measurement techniques.

DATA SOURCES

Human and veterinary clinical studies, research articles, reviews, and textbooks with no date restrictions with a focus on techniques for intra-abdominal pressure (IAP) measurement and their limitations.

HUMAN DATA SYNTHESIS

Human literature has established the intravesicular method as the gold standard for indirect measurement of IAP. However, current research has explored the intragastric method as a valid alternative. Recently, debate has focused on the shortcomings of the various measurement methods.

VETERINARY DATA SYNTHESIS

Early human literature using dogs as models contributed to the original data for IAP measurements in small animals. Since that time, a number of clinical studies and 1 case report have contributed to that original information. A reference interval for IAP measured by the intravesicular method has recently been determined in healthy cats.

CONCLUSIONS

Further studies investigating IAP in critically ill veterinary patients are required to establish the optimal technique for this measurement in veterinary medicine.

Atrial and brain natriuretic peptide changes in an experimental model of intra-abdominal hypertension

BACKGROUND

Intra-abdominal hypertension (IAH) can have a profound impact on the cardiovascular system. We hypothesized that natriuretic peptides (Nt-pro-ANP and Nt-pro-BNP) are produced in response to the cardiovascular changes observed in an experimental model of IAH.

MATERIALS AND METHODS

Eleven female pigs were enrolled in this study. Four experimental phases were created: a baseline phase for instrumentation (T1); two subsequent phases (T2 and T3), in which helium pneumoperitoneum was established at 20 and 35 mm Hg, respectively; and the final phase (T4), in which abdominal desufflation took place. Hemodynamic parameters and concentrations of Nt-pro-ANP and Nt-pro-BNP were measured.

RESULTS

Central venous pressure and pulmonary capillary wedge pressure increased significantly during the elevation of intra-abdominal pressure (IAP) and returned to baseline after abdominal desufflation. Right and left transmural pressures remained unaffected by the elevation of IAP. Cardiac output decreased in phases T2 and T3 and was restored to baseline levels after abdominal desufflation. Systemic and pulmonary vascular resistances increased significantly with IAH and decreased after abdominal desufflation. Nt-pro-ANP did not change significantly in comparison to baseline. Nt-pro-BNP increased significantly in comparison to baseline at T3 and T4. Peak Nt-pro-BNP levels at T3 (peak IAP) correlated positively with indices of afterload at this time point, that is, systemic vascular resistance and pulmonary vascular resistance (r(2) = 0.38, P = 0.042 and r(2) = 0.55, P = 0.009, respectively). A strong negative correlation between Nt-pro-BNP and cardiac output at T3 was also demonstrated (r(2) = 0.58, P = 0.006).

CONCLUSIONS

IAH resulted in cardiovascular compromise. The unchanged Nt-pro-ANP concentrations might reflect unaltered atrial stretch with IAH, despite the elevation of right atrial filling pressure. The significant increase of Nt-pro-BNP in response to high levels of IAP may reflect left ventricular strain and dysfunction due to the severe IAH and provide an alternative marker in the monitoring of IAH.

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.

Should we measure intra-abdominal pressures in every intensive care patient?

Intra-abdominal pressure (IAP) is seldom measured by default in intensive care patients. This review summarises the current evidence on the prevalence and risk factors of intra-abdominal hypertension (IAH) to assist the decision-making for IAP monitoring.IAH occurs in 20% to 40% of intensive care patients. High body mass index (BMI), abdominal surgery, liver dysfunction/ascites, hypotension/vasoactive therapy, respiratory failure and excessive fluid balance are risk factors of IAH in the general ICU population. IAP monitoring is strongly supported in mechanically ventilated patients with severe burns, severe trauma, severe acute pancreatitis, liver failure or ruptured aortic aneurysms. The risk of developing IAH is minimal in mechanically ventilated patients with positive end-expiratory pressure < 10 cmH2O, PaO2/FiO2 > 300, and BMI < 30 and without pancreatitis, hepatic failure/cirrhosis with ascites, gastrointestinal bleeding or laparotomy and the use of vasopressors/inotropes on admission. In these patients, omitting IAP measurements might be considered.In conclusions, clear guidelines to select the patients in whom IAP measurements should be performed cannot be given at present. In addition to IAP measurements in at-risk patients, a clinical assessment of the signs of IAH should be a part of every ICU patient's bedside evaluation, leading to prompt IAP monitoring in case of the slightest suspicion of IAH development.

Hypoperfusion, shock states, and abdominal compartment syndrome (ACS)

Cardiovascular dysfunction and failure are commonly encountered in patients with intra-abdominal hypertension or abdominal compartment syndrome. Accurate assessment and optimization of preload, afterload, and contractility are essential to restoring end-organ perfusion and maximizing patient survival. Application of a goal-directed resuscitation strategy, including abdominal decompression, when indicated, improves cardiac function, reverses end-organ failure, and minimizes intra-abdominal hypertension-related patient morbidity and mortality.

Intra-abdominal Hypertension and Abdominal Compartment Syndrome

Intra-abdominal hypertension has a prevalence of at least 50% in the critically ill population and has been identified as an independent risk factor for death. Yet, many of the members of the critical care team do not assess for intra-abdominal hypertension and are unaware of the consequences of untreated intra-abdominal hypertension. These consequences can be abdominal compartment syndrome, multisystem organ failure, and death. This article provides an overview of the pathophysiology of intra-abdominal hypertension and abdominal compartment syndrome. In addition, the evidence-based definitions, guidelines, and recommendations of the World Society of the Abdominal Compartment Syndrome are presented.

Abdominal compartment syndrome - Intra-abdominal hypertension: Defining, diagnosing, and managing

Abdominal compartment syndrome (ACS) and intra-abdominal hypertension (IAH) are increasingly recognized as potential complications in intensive care unit (ICU) patients. ACS and IAH affect all body systems, most notably the cardiac, respiratory, renal, and neurologic systems. ACS/IAH affects blood flow to various organs and plays a significant role in the prognosis of the patients. Recognition of ACS/IAH, its risk factors and clinical signs can reduce the morbidity and mortality associated. Moreover, knowledge of the pathophysiology may help rationalize the therapeutic approach. We start this article with a brief historic review on ACS/IAH. Then, we present the definitions concerning parameters necessary in understanding ACS/IAH. Finally, pathophysiology aspects of both phenomena are presented, prior to exploring the various facets of ACS/IAH management.

Renal dysfunction associated with intra-abdominal hypertension and the abdominal compartment syndrome

Once considered mostly a postsurgical condition, intra-abdominal hypertension (IAH) and the abdominal compartment syndrome (ACS) are now thought to increase morbidity and mortality in many patients receiving medical or surgical intensive care. Animal data and human observational studies indicate that oliguria and acute kidney injury are early and frequent consequences of IAH/ACS and can be present at relatively low levels of intra-abdominal pressure (IAP). Among medical patients at particular risk are those with septic shock and severe acute pancreatitis, but the adverse effects of IAH may also be seen in cardiorenal and hepatorenal syndromes. Factors predisposing to IAH/ACS include sepsis, large volume fluid resuscitation, polytransfusion, mechanical ventilation with high intrathoracic pressure, and acidosis, among others. Transduction of bladder pressure is the gold standard for measuring intra-abdominal pressure, and several nonsurgical methods can help reduce IAP. The role of renal replacement therapy for volume management is not well defined but may be beneficial in some cases. IAH/ACS is an important possible cause of acute renal failure in critically ill patients and screening may benefit those at increased risk.

Abdominal compartment syndrome in trauma resuscitation

PURPOSE OF REVIEW

Swelling is inexorably linked to shock and resuscitation in trauma. In many forms, swelling complicates and interacts with traumatic injury to raise pressures in the abdomen, resulting in intraabdominal hypertension, which may overtly manifest as abdominal compartment syndrome (ACS) driving multiple organ failure. Despite renewed clinical interest in posttraumatic intraabdominal pressure, there remains a chiasm between knowledge of the risks and clinical interventions to mitigate them. This review provides a concise overview of definitions, risk factors, diagnosis and management using an illustrative trauma case.

RECENT FINDINGS

Intraabdominal pressure commonly increases following trauma, wherein ACS may manifest earlier than generally appreciated and complicate other insults such as shock and hemorrhage. Contemporary resuscitation strategies may exacerbate intraabdominal hypertension, particularly massive crystalloid resuscitation. Although unproven, the recent transition to crystalloid restriction and high plasma resuscitation strategies may influence the prevalence of ACS. Nonetheless, aggressive intraabdominal pressure monitoring should be mandatory in the critically ill. Despite potential nonoperative options, decompressive laparotomy remains the only definitive but often morbid treatment.

SUMMARY

ACS results from many dysfunctions acting in concert with each other in self-propagating vicious cycles. Starting with greater awareness, it is imperative that the growing knowledge should be translated into clinical practice.

Decompressive laparotomy for abdominal compartment syndrome in children: before it is too late

PURPOSE

Abdominal compartment syndrome (ACS) in children is an infrequently reported, rapidly progressive, and often lethal condition underappreciated in the pediatric population. This underrecognition can result in a critical delay in diagnosis causing increased morbidity and mortality. This study examines the clinical course of patients treated for ACS at our institution.

METHODS

A review of children requiring an emergency laparotomy (n = 264) identified 26 patients with a diagnosis of ACS. ACS was defined as sustained intraabdominal hypertension (bladder pressure >12 mm Hg) that was associated with new onset organ dysfunction or failure.

RESULTS

Patients ranged in age from 3 months to 17 years old and were cared for in the pediatric intensive care unit (PICU). Twenty-seven percent (n = 7) were transferred from referring hospitals, 50% (n = 13) were admitted directly from the emergency department, and 23% (n = 6) were inpatients before being transferred to PICU. Admission diagnoses included infectious enterocolitis (n = 12), postsurgical procedure (n = 10), and others (n = 4). Patients progressed to ACS rapidly, with most requiring decompressive laparotomy within 8 hours of PICU admission (range, <1-96 hours). Preoperatively, all patients had maximum ventilatory support and oliguria, 85% (n = 22) required vasopressors/inotropes, and 31% (n = 8) required hemodialysis. Mean bladder pressure was 25 mm Hg (range, 12-44 mm Hg). In 42% (n = 11), cardiac arrest preceeded decompressive laparotomy. All patients showed evidence of tissue ischemia before decompressive laparotomy with an average preoperative lactate of 8 (range, 1.2-20). Decompressive laparotomy was done at the bedside in the PICU in 13 patients and in the operating room in 14 patients. Abdominal wounds were managed with open vacuum pack or silastic silo dressings. Physiologic data including fluid resuscitation, oxygen index, mean airway pressure, vasopressor score, and urine output were recorded at 6-hour intervals beginning 12 hours before decompressive laparotomy and extending 12 hours after operation. The data demonstrate improvement of all physiologic parameters after decompressive laparotomy except for urine output, which continued to be minimal 12 hours post intervention. Mortality was 58% (n = 15) overall. The only significant factor related to increased mortality was bladder pressure (P = .046; odds ratio, 1.258). Cardiac arrest before decompressive laparotomy, need for hemodialysis, and transfer from referring hospital also trended toward increased mortality but did not reach significance.

CONCLUSION

Abdominal compartment syndrome in children carries a high mortality and may be a consequence of common childhood diseases such as enterocolitis. The diagnosis of ACS and the potential need for emergent decompressive laparotomy may be infrequently discussed in the pediatric literature. Increased awareness of ACS may promote earlier diagnosis, treatment, and possibly improve outcomes.

Ischemia as a possible effect of increased intra-abdominal pressure on central nervous system cytokines, lactate and perfusion pressures

INTRODUCTION

The aims of our study were to evaluate the impact of increased intra-abdominal pressure (IAP) on central nervous system (CNS) cytokines (Interleukin 6 and tumor necrosis factor), lactate and perfusion pressures, testing the hypothesis that intra-abdominal hypertension (IAH) may possibly lead to CNS ischemia.

METHODS

Fifteen pigs were studied. Helium pneumoperitoneum was established and IAP was increased initially at 20 mmHg and subsequently at 45 mmHg, which was finally followed by abdominal desufflation. Interleukin 6 (IL-6), tumor necrosis factor alpha (TNFa) and lactate were measured in the cerebrospinal fluid (CSF) and intracranial (ICP), intraspinal (ISP), cerebral perfusion (CPP) and spinal perfusion (SPP) pressures recorded.

RESULTS

Increased IAP (20 mmHg) was followed by a statistically significant increase in IL-6 (p = 0.028), lactate (p = 0.017), ICP (p < 0.001) and ISP (p = 0.001) and a significant decrease in CPP (p = 0.013) and SPP (p = 0.002). However, further increase of IAP (45 mmHg) was accompanied by an increase in mean arterial pressure due to compensatory tachycardia, followed by an increase in CPP and SPP and a decrease of cytokines and lactate.

CONCLUSIONS

IAH resulted in a decrease of CPP and SPP lower than 60 mmHg and an increase of all ischemic mediators, indicating CNS ischemia; on the other hand, restoration of perfusion pressures above this threshold decreased all ischemic indicators, irrespective of the level of IAH.