Renal failure and abdominal hypertension after liver transplantation: determination of critical intra-abdominal pressure

Increased intra-abdominal pressure linked to worse long-term prognosis among patients with orthotopic liver transplantation: a retrospective, observational study

OBJECTIVE

To investigate the prognostic value of intra-abdominal pressure (IAP) among patients with orthotopic liver transplantation (OLT).

PATIENTS

We enrolled adult patients admitted in the Department of Critical Care Medicine of the First Affiliated Hospital of Sun Yat-sen University after undergoing liver transplantation from January 2018 to March 2022.

METHODS AND RESULTS

A total of 382 patients were included, with 73 patients who died within 1 year after admission. Intra-abdominal Hypertension (IAH) was defined as a sustained IAP ≥ 12 mmHg. The incidence of IAH among liver transplant patients was 46.2%. The IAP and sequential organ failure assessment (SOFA) scores were significantly lower in survivors than non-survivors (P < 0.05). Restricted cubic spline (RCS) analysis found that an IAP level above 16 mmHg was significantly associated with an elevated risk of 1-year mortality, and Kaplan-Meier survival curves further validated this finding (log-rank P < 0.001). Multivariate Cox proportional hazards regression model indicated that patients in IAH grade III (HR: 3.16, 95% CI: 1.31-7.62, P = 0.010) and IV (HR: 9.93, 95% CI: 2.84-34.7, P < 0.001) had significantly higher 1-year mortality risks adjusted by SOFA score classifications compared to individuals without IAH. Maximum IAP levels alone and a modified SOFA score incorporating IAH grade demonstrated satisfactory performance in predicting in-hospital mortality among OLT patients (AUC: 0.710, 0.834, respectively).

CONCLUSIONS

Elevated intra-abdominal pressure above 16 mmHg was significantly related with worse 1-year survival among OLT patients. Both maximum IAP alone and SOFA score incorporated with IAH components showed strong prognostic values for in-hospital mortality of these individuals.

Acute Kidney Injury Management Strategies Peri-Cardiovascular Interventions

In many countries, the aging population and the higher incidence of comorbid conditions have resulted in an ever-growing need for cardiac interventions. Acute kidney injury (AKI) is a common complication of these interventions, associated with higher mortalities, chronic or end-stage kidney disease, readmission rates, and hospital and post-discharge costs. The AKI pathophysiology includes contrast-associated AKI, hemodynamic changes, cardiorenal syndrome, and atheroembolism. Preventive measures include limiting contrast media dose, optimizing hemodynamic conditions, and limiting exposure to other nephrotoxins. This review article outlines the current state-of-art knowledge regarding AKI pathophysiology, risk factors, preventive measures, and management strategies in the peri-interventional period.

Intra-Abdominal Hypertension and Compartment Syndrome after Pediatric Liver Transplantation: Incidence, Risk Factors and Outcome

In pediatric liver transplantation (pLT), the risk for the manifestation and relevance of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) is high. This observational study aimed to evaluate the incidence, relevance and risk factors for IAH and ACS by monitoring the intra-abdominal pressure (IAP), macro- and microcirculation (near-infrared spectroscopy (NIRS)), clinical and laboratory status and outcomes of 27 patients (16 female) after pLT (median age at pLT 35 months). Of the patients, 85% developed an elevated IAP, most of them mild. However, 17% achieved IAH° 3, 13% achieved IAH° 4 and 63% developed ACS. A multiple linear regression analysis identified aortal hepatic artery anastomosis and cold ischemia time (CIT) as risk factors for increased IAP and longer CIT and staged abdominal wall closure for ACS. ACS patients had significantly longer mechanical ventilation (p = 0.004) and LOS-PICU (p = 0.003). No significant correlation between NIRS or biliary complications and IAH or ACS could be shown. IAH and ACS after pLT were frequent. NIRS or grade of IAH alone should not be used for monitoring. A longer CIT is an important risk factor for higher IAP and ACS. Therefore, approaches such as the ex vivo machine perfusion of donor organs, reducing CIT effects on them, have great potential. Our study provides important basics for studying such approaches.

Pathophysiology of Acute Kidney Injury in Critical Illness: A Narrative Review

Acute kidney injury (AKI) is a syndrome that entails a rapid decline in kidney function with or without injury. The consequences of AKI among acutely ill patients are dire and lead to higher mortality, morbidity, and healthcare cost. To prevent AKI and its short and long-term repercussions, understanding its pathophysiology is essential. Depending on the baseline kidney histology and function reserves, the number of kidney insults, and the intensity of each insult, the clinical presentation of AKI may differ. While many factors are capable of inducing renal injury, they can be categorized into a few processes. The three primary processes reported in the literature are hemodynamic changes, inflammatory reactions, and nephrotoxicity. The majority of patients with AKI will suffer from more than one during their development and/or progression of AKI. Moreover, the development of one usually leads to the instigation of another. Thus, the interactions and progression between these mechanisms may determine the severity and duration of the AKI. Other factors such as organ crosstalk and how our concurrent therapies interact with these mechanisms complicate the pathophysiology of the progression of the AKI even further. In this narrative review article, we describe these three main pathophysiological processes that lead to the development and progression of AKI. © 2022 American Physiological Society. Compr Physiol 12: 1-14, 2022.

The Intensivist's Perspective of Shock, Volume Management, and Hemodynamic Monitoring

One of the primary reasons for intensive care admission is shock. Identifying the underlying cause of shock (hypovolemic, distributive, cardiogenic, and obstructive) may lead to entirely different clinical pathways for management. Among patients with hypovolemic and distributive shock, fluid therapy is one of the leading management strategies. Although an appropriate amount of fluid administration might save a patient's life, inadequate (or excessive) fluid use could lead to more complications, including organ failure and mortality due to either hypovolemia or volume overload. Currently, intensivists have access to a wide variety of information sources and tools to monitor the underlying hemodynamic status, including medical history, physical examination, and specific hemodynamic monitoring devices. Although appropriate and timely assessment and interpretation of this information can promote adequate fluid resuscitation, misinterpretation of these data can also lead to additional mortality and morbidity. This article provides a narrative review of the most commonly used hemodynamic monitoring approaches to assessing fluid responsiveness and fluid tolerance. In addition, we describe the benefits and disadvantages of these tools.

Abdominal compartment syndrome: Current concepts and management

Abdominal compartment syndrome occurs when 2 or more anatomic compartments have a sustained intra-abdominal pressure >20mmHg, associated with organ failure. Incidence is 2% and prevalence varies from 0% to 36.4%. A literature search was conducted utilizing different databases. Articles published from 1970 to 2018 were included, in English or Spanish, to provide the concepts, classifications, and comprehensive management in the approach to abdominal compartment syndrome, for its treatment and the prevention of severe complications associated with the entity. Intravesical pressure measurement is the standard diagnostic method. Treatment is based on evacuation of the intraluminal content, identification and treatment of intra-abdominal lesions, improvement of abdominal wall compliance, and optimum administration of fluids and tissue perfusion. Laparotomy is generally followed by temporary abdominal wall closure 5 to 7 days after surgery. Reconstruction is performed 6 to 12 months after the last operation. Abdominal compartment syndrome should be diagnosed and operated on before organic damage from the illness occurs. Kidney injury can frequently progress and is a parameter for considering abdominal decompression. Having a biomarker for early damage would be ideal. Surgical treatment is successful in the majority of cases. A multidisciplinary focus is necessary for the intensive care and reconstructive needs of the patient. Thus, efforts must be made to define and implement strategies for patient quality of life optimization.

Monitoring intra-abdominal pressure after liver transplantation in children

IAH after LTX can impair perfusion and threaten graft viability. This study aimed to assess the feasibility of longitudinal IAP measurements as an IAH screening method in children after LTX. A cohort of 23 children with a mean age (range) 3.1 (3 months-14 years) who underwent LTX between May 2017 and February 2018 were evaluated retrospectively. Longitudinal IAP measurements were compared to bedside Doppler US monitoring data. In total, 425 IAP measurements and 257 US examinations were performed. The mean ± SD (range) time expenditure for IAP measurement was 1.9 ± 0.4 (0.5-3.2) minutes. The mean post-operative IAP was 7.9 ± 3.6 (1-25) mm Hg. IAH (IAP ≥ 10 mm Hg) was noted in 102 (24%) of 257 measurements. Agitation had a significant impact on IAP (estimate: 9.3 mm Hg, CI: 6.72-11.97, P < .01). In patients with TAC, IAP was increased (6.7 ± 2.1 vs 8.7 ± 3.1 mm Hg, P = .02) while peak portal venous velocities decreased (38 ± 27 vs 26 ± 22 cm/s, P = .03) after patch reduction. An abdominal compartment syndrome with severely impaired vascular flow was noted in one patient. Episodes of elevated IAP were noted in a large proportion of patients, underscoring the need for IAP monitoring in pediatric liver transplant recipients. The safety and low time expenditure associated with IAP measurement could be included easily into standard nursing procedures for these patients.

Renal implications of increased intra-abdominal pressure: are the kidneys the canary for abdominal hypertension?

INTRODUCTION

Increased intra-abdominal pressure (IAP) or intra-abdominal hypertension (IAH) is a cause of organ dysfunction in critically ill patients and is independently associated with mortality. The kidneys seem to be especially vulnerable to IAH induced dysfunction and renal failure is one of the most consistently described organ dysfunctions associated with IAH. The aim of this paper is to review the historical background, awareness, definitions, pathophysiologic implications and treatment options for IAP induced renal failure.

METHODS

This review will focus on the available literature on IAH-induced renal dysfunction. A Medline and PubMed search was performed in order to find an answer to the question "What is the impact of increased IAP on renal function in the critically ill?". The resulting references were included in the current review on the basis of relevance and scientific merit.

RESULTS

Renal dysfunction in IAH is a multifactorial process. The mechanisms involved have not been clarified completely. However, decreased cardiac output, altered renal blood flow and hormonal changes have been implicated. Decompression seems to have a beneficial effect on renal dysfunction, although there are some conflicting data. This may be due to the fact that there is no consensus on indications for decompression, both in terms of IAP values and of timing. An overview of current literature is provided and some interesting leads for future research are suggested.

CONCLUSION

IAH can cause renal dysfunction. Therefore, IAP measurements should be considered in our daily practice and preventive measures should be taken to avoid (deterioration of) renal failure in patients with IAH. Decompression may have a beneficial effect in patients with established IAH and renal failure.

Incidence, Risk Factors and Outcome Associations of Intra-Abdominal Hypertension in Critically Ill Patients

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are significantly associated with morbidity and mortality. We performed a prospective observational study and applied recently published consensus criteria to measure and describe the incidence of IAH and ACS, identify risk factors for their development and define their association with outcomes. We studied 100 consecutive patients admitted to our general intensive care unit. We recorded relevant demographic, clinical data and maximal (max) and mean intra-abdominal pressure (IAP). We measured and defined IAH and ACS using consensus guidelines. Of our study patients, 42% (by IAPmax) and 38% (by IAPmean) had IAH. Patients with IAH had greater mean body mass index (30.4±9.6 vs 25.4±5.6 kg/m2, P=0.005), Acute Physiology and Chronic Health Evaluation III score (78.2±28.5 vs 65.5±29.2, P=0.03) and central venous pressure (12.8±4.8 vs 9.2±3.5 mmHg, P <0.001), lower abdominal perfusion pressure (67.6±13.5 vs 79.3±17.3 mmHg, P <0.001) and lower filtration gradient (51.2±14.8 vs 71.6±17.7 mmHg; P <0.001). Risk factors associated with IAH were body mass index ≥30 (P <0.001), higher central venous pressure (P <0.001), presence of abdominal infection (P=0.005) and presence of sepsis on admission (P=0.035). Abdominal compartment syndrome developed in 4% of patients. IAP was not associated with an increased risk of mortality after adjusting for other confounders. We conclude that, in a general population of critically ill patients, using consensus guidelines, IAH was common and significantly associated with obesity and sepsis on admission. In a minority of patients, IAH was associated with abdominal compartment syndrome. In this cohort IAH was not associated with an increased risk of mortality.

The evaluation of the effect of body positioning on intra-abdominal pressure measurement and the effect of intra-abdominal pressure at different body positioning on organ function and prognosis in critically ill patients

PURPOSE

Current literatures confirmed the widespread and frequent development of both intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) among the critically ill with a significant associated risk of organ failure and increased mortality. The 2004 International ACS Consensus Conference committee proposed that intra-abdominal pressure (IAP) be measured in complete supine position; however, the supine position of intensive care unit (ICU) patients (<30° of bed increase) presented a significant risk for ventilator-associated pneumonia. Therefore, the potential contribution of head of bed (HOB) position in elevating IAP should be considered. The purpose of this study was to evaluate the effect of body positioning on IAP measurement and the effect of IAP at different body positions on organ function and prognosis in critically ill patients.

MATERIALS AND METHODS

A prospective cohort study to investigate the effect of different patient positioning on IAP, organ function, and prognosis was conducted on 88 patients admitted to a medical-surgical ICU. On admission, patients' epidemiological data and risk factors for IAH were studied; daily mean IAPs, abdominal perfusion pressure, filtration gradient, Acute Physiology and Chronic Health Evaluation II score, sequential organ failure assessment score, and multiple organ dysfunction scores were registered; next, conventional hemodynamic variables, intrathoracic blood volume index, global end-diastolic volume index and extravascular lung water using the pulse contour cardiac output system were recorded. Intra-abdominal pressures were recorded through a bladder catheter every 4 hours on the first day. Intra-abdominal pressure was measured with the patient HOB increases from 0° to 45°. Mean arterial pressure was recorded simultaneously, whereas abdominal perfusion pressure and filtration gradient (FG) were also calculated simultaneously.

RESULTS

The main results of this study were the incidence of IAH (28.4%) and ACS (2.3%) in ICU patients; the significant and independent relationship between IAP and HOB increases. Considering the absolute numbers of IAP, the HOB of 10° and 20° showed slight differences, whereas that of 30° and 45° showed clinically significant differences; HOB elevation was associated with clinically significant decreases in abdominal perfusion pressure and FG; patients with IAH were prone to the development of shock and multiple organ dysfunction syndrome and exhibited significantly lower intrathoracic blood volume index and global end-diastolic volume index and higher extravascular lung water.

CONCLUSIONS

There is a significant and independent relationship between IAP and HOB positioning in critically ill patients, with the HOB of 30° and 45° showing significant difference. Abdominal perfusion pressure and FG are significantly decreased when the patient's HOB is elevated. The potential contribution of body position in elevating IAP should be considered in critically ill patients with the risk of IAH and ACS.

Critical care issues in patients after liver transplantation

The majority of patients who undergo liver transplantation (LT) spend some time in the intensive care unit during the postoperative period. For some, this is an expected part of the immediate posttransplant recovery period, whereas for others, the stay is more prolonged because of preexisting conditions, intraoperative events, or postoperative complications. In this review, 4 topics that are particularly relevant to the postoperative intensive care of LT recipients are discussed, with an emphasis on current knowledge specific to this patient group. Infectious complications are the most common causes of early posttransplant morbidity and mortality. The common patterns of infection seen in patients after LT and their management are discussed. Acute kidney injury and renal failure are common in post-LT patients. Kidney injury identification, etiologies, and risk factors and approaches to management are reviewed. The majority of patients will require weaning from mechanical ventilation in the immediate postoperative period; the approach to this is discussed along with the approach for those patients who require a prolonged period of mechanical ventilation. A poorly functioning graft requires prompt identification and appropriate management if the outcomes are to be optimized. The causes of poor graft function are systematically reviewed, and the management of these grafts is discussed.

Abdominal compartment syndrome caused by intra-abdominal hypertension after liver transplantation: an analysis of two cases

Intra-abdominal hypertension (IAH) may cause multiple organ dysfunction/failure, which can progressively develop into lethal abdominal compartment syndrome (ACS). There exist many kinds of factors causing IAH after liver transplantation. Once ACS develops, the prognosis is very poor. Here, we report two cases of ACS after liver transplantation. In addition, the relevant literature was discussed to improve our understanding of the syndrome.

Usefulness of intra-abdominal pressure in a predominantly medical intensive care unit

BACKGROUND

The deleterious effects of elevated intra-abdominal pressure (IAP) have been known for more than a century. The proposed objectives were to measure changes in IAP and analyze increase-related factors and complications and whether high IAP and its persistence are related to complications and mortality in a predominantly medical intensive care unit.

METHODS

Over a 1-year period, we conducted a prospective cohort study in which IAP was measured using the bladder method. Hospitalization time, demographic variables, diagnosis on admission, APACHE II score, and clinical complications were recorded.

RESULTS

A total of 130 patients were studied. Overall mean IAP was 12.3 mm Hg (standard deviation [SD], 3.79; 95% confidence interval [CI], 11.7-13), and on the first day, 12.68 mm Hg (SD, 5.32; 95% CI, 11.8-13.6); maximum IAP was 16.4 mm Hg (SD, 4.6; 95% CI, 15.6-17.2). A positive correlation was found between IAP, APACHE (Acute Physiology And Chronic Health Evaluation) II, and age. Higher IAP values were independently associated with higher age, prolonged activated partial thromboplastin time, need for dialysis, and intolerance to enteral feeding. The value showing the best sensitivity and specificity in predicting mortality was persistence of IAP 20 mm Hg or greater for 4 days or more. The number of days with IAP 20 mm Hg or greater was a factor associated with a higher risk of death (odds ratio, 2.3). Patients who died showed a tendency to increased IAP.

CONCLUSION

In this study, a threshold IAP of 20 mm Hg and its permanence over time were the best predictive factors of complications and mortality. Among other relationships, we also observed that older patients had higher IAP. High IAP was a cause of intolerance to enteral nutrition.

Current insights in intra-abdominal hypertension and abdominal compartment syndrome: open the abdomen and keep it open!

BACKGROUND AND AIMS

The abdominal compartment syndrome (ACS) is associated with organ dysfunction and mortality in critically ill patients. Furthermore, the deleterious effects of increased IAP have been shown to occur at levels of intra-abdominal pressure (IAP) previously deemed to be safe. The aim of this article is to provide an overview of all aspects of this underrecognized pathological syndrome for surgeons.

METHODS AND CONTENTS

This review article will focus primarily on the recent literature on ACS as well as the definitions and recommendations published by the World Society for the Abdominal Compartment Syndrome. The definitions regarding increased IAP will be listed, followed by a brief but comprehensive overview of the different mechanisms of organ dysfunction associated with intra-abdominal hypertension (IAH). Measurement techniques for IAP will be discussed, as well as recommendations for organ function support in patients with IAH. Finally, surgical treatment and management of the open abdomen are briefly discussed, as well as some minimally invasive techniques to decrease IAP.

CONCLUSIONS

The ACS was first described in surgical patients with abdominal trauma, bleeding, or infection, but in recent years ACS has also been described in patients with other pathologies such as burn injury and sepsis. Some of these so-called nonsurgical patients will require surgery to treat their ACS. This review article is intended to provide surgeons with a clear insight into the current state of knowledge regarding IAH, ACS, and the impact of IAP on the critically ill patient.

Intra-abdominal hypertension: incidence and association with organ dysfunction during early septic shock

PURPOSE

The objective of this article is to study the cumulative incidence of intra-abdominal hypertension (IAH) in septic shock (SS) patients during the first 72 hours of intensive care unit (ICU) admission and to determine if the presence and severity of IAH are associated with sepsis morbidity and mortality.

MATERIALS AND METHODS

Eighty-one consecutive SS patients admitted to a surgical-medical ICU of an academic university hospital (January 2005 to January 2006) were included. Intra-abdominal pressure (IAP) and abdominal perfusion pressure (APP) were measured every 6 h (intermittently) for 72 h. Intra-abdominal pressure was registered as minimal, mean, and maximal values per day, during shock and throughout the study period. Intra-abdominal hypertension was diagnosed if IAP remained 12 mm Hg or higher on 2 consecutive measurements and stratified according to the most recent consensus definition (www.wsacs.org).

RESULTS

According to maximal and mean IAP values, 67 (82.7%) and 62 (76.5%) of the patients developed IAH during the study period, respectively. Mean IAP values remained stable throughout the study period. Surgical patients had a higher incidence of IAH than medical patients (93% vs 73%, P < .009). Maximal IAPs were normally distributed, with nonsurvivors exhibiting significantly higher IAP levels during shock (survivors, 17.2 +/- 5.3; nonsurvivors, 19.9 +/- 5.6 mm Hg; P < .04). Patients with IAH exhibited significantly lower values of APP and diuresis, higher values of lactate and creatinine, and higher maximal norepinephrine doses, and were more frequently mechanically ventilated (P < .05 for all). Increasing degrees of IAH and the development of the abdominal compartment syndrome were associated with lower APP and higher maximal serum creatinine levels (P < .03 for both).

CONCLUSIONS

Septic shock patients have a very high incidence of IAH, which seems to be associated with the severity of shock and could be related to the development of organ dysfunctions, particularly renal dysfunction. Intra-abdominal pressure should be routinely monitored during the course of SS.

Current insights in intra-abdominal hypertension and abdominal compartment syndrome

A compartment syndrome exists when increased pressure in a closed anatomic space threatens the viability of the tissue within the compartment. When this occurs in the abdominal cavity it threatens not only the function of the intra-abdominal organs, but it can have a devastating effect on distant organs as well. Recent animal and human data suggest that the adverse effects of elevated intra-abdominal pressure (IAP) can occur at lower levels than previously thought and even before the development of clinically overt abdominal compartment syndrome (ACS). The ACS is not a disease but truly a syndrome, a spectrum of symptoms and signs that can and mostly does have multiple causes. It is only recently that this condition received a heightened awareness. This article reflects the current state of knowledge on intra-abdominal pressure regarding etiology, epidemiology, diagnosis, IAP measurement, organ dysfunction, prevention and treatment.

Intra-abdominal hypertension is an independent cause of acute renal failure after orthotopic liver transplantation

An independent association between acute renal failure (ARF) and intra-abdominal hypertension (IAH) after liver transplantation has not been established previously. The aim of this retrospective study was to understand the role of IAH as an independent risk factor for ARF in the early postoperative period. This study involved 62 subjects who underwent liver transplantation. Intra-abdominal pressure (IAP) was measured in the first three days after surgery by using the urinary bladder technique. An IAP of at least 20 mmHg per day was defined as IAH. Clinical parameters between group IAH and group NO-IAH were compared in terms of the incidence of ARF, blood creatinine levels, blood urea nitrogen (BUN) levels, urine volume per hour and glomerular filtration gradient (GFG). Hemodynamic variations were recorded in the first three postoperative days between group ARF and group NO-ARF. The perioperative suspected risk factors of ARF were determined for statistical evaluation using correlation coefficients and logistic regression analysis. In group IAH, 45.8% patients developed ARF as against 7.9% in group NO-IAH; GFG was significantly lower at 0-72 h after surgery; and blood creatinine levels, BUN levels, urine volume per hour were significantly different at 24-72 h after surgery compared with group NO-IAH. The patients with ARF were not significantly different from those without ARF in terms of central venous pressure, pulmonary artery pressure and mean arterial pressure (MAP) in the first three postoperative days despite a significant increase in heart rate at 24-72h after operation. Postoperative IAH, intraoperative MAP and intraoperative blood transfusion volume of more than 15 U were found to be independent risk factors for ARF. IAH impaired renal function and was an independent risk factor for ARF after liver transplantation. Routine measurement should be taken to monitor IAP every eight hours postoperatively.

Analysis of renal function in the immediate postoperative period after partial liver transplantation

Although renal dysfunction is common after liver transplantation, postoperative renal function after split liver transplantation (SLT) has not been well studied. Renal function immediately after surgery was analyzed retrospectively in 16 patients that received a SLT (SLT group). The results were compared with corresponding data from 31 matched patients that received a full-size liver transplant (FSLT group) during the same period. Serum creatinine (SCr) was measured before surgery, and, after transplantation, daily during the first week and at days 14, 21, and 28. Renal dysfunction (RD) was defined as the requirement for renal replacement therapy (RRT) or a 100% increase in SCr if the basal value had been <1.0 mg/dL or a 50% increase in SCr if the basal value had been >1.0 mg/dL. SCr had to be at least 1.5 mg/dL for a diagnosis of RD to be considered. The classification of RD was: mild, SCr 1.5-2.4 mg/dL; moderate, SCr 2.5-4.0 mg/dL; or severe, SCr >4.0 mg/dL (the requirement for RRT). Both donor and recipient age and cold ischemia time were lower in the SLT group than in the FSLT group (P < 0.05). Length of surgery was longer in the SLT group (P < 0.05). There were no significant differences between groups with respect to Model for End-Stage Liver Disease scores, the need for transfusions, the length of admission to the intensive care unit (ICU), survival rate, individual severity index, or sepsis-related organ failure assessment scores at the time of diagnosing RD. Immunosuppression regimens were similar in both groups. RD developed in 82% of SLT patients, but in only 58% of FSLT patients (P = not significant [NS]). Among SLT patients, RD (23.0% mild, 15.5% moderate, and 61.5% severe) was more severe (P = 0.007) than in FSLT patients (63.1% mild, 15.8% moderate, and 24.1% severe). The requirement for RRT in the SLT group (43.7%) was significantly greater (P < 0.05) than that in the FSLT group (12.9%). This finding may be due to the different incidence of sepsis in the 2 groups (SLT 37.5% vs. FSLT 9.7%; P < 0.05). In conclusion, although the number of patients studied was small, our data suggest a higher incidence of RD and a greater requirement for RRT in patients that receive a split liver graft than in those that receive a full size liver graft.

Abdominal hypertension and liver dysfunction in intensive care unit patients: an "on-off" phenomenon?

Intra-abdominal hypertension (IAH) can affect liver hemodynamics but it is not known if has a significant clinical impact on liver function. The aim of this study was to investigate the relationship between IAH and liver function. A prospective study was performed in 110 adult intensive care unit (ICU) patients. Intra-abdominal pressure (IAP) was measured on admission and every other day, and liver sequential organ failure assessment (SOFA) score was collected whenever IAP was measured. IAH was defined by a IAP >or= 10 mm Hg, and liver dysfunction was defined by a hepatic SOFA score >or= 2. An overall IAH incidence of 56.3% was found (n = 62). Thirty-three patients presented a liver SOFA score >or= 2, with an overall incidence of 30%. Liver SOFA score of the group of patients with abdominal hypertension was higher than in group of patients without abdominal hypertension. (0.8 +/- 1.05 vs 0.4 +/- 0.7; P < .05), but IAH and liver dysfunction were not significantly associated (chi2 = 2.03; P = .15). When the whole sample was divided according to the worst IAP score (IAP < 10, IAP between 10 and 15, and IAP > 15), the corresponding liver dysfunction scores in the three groups were 0.35 +/- 0.6, 0.74 +/- 1, and 1.2 +/- 1.3, respectively (P = .01). A strict association between IAH and liver dysfunction was not found. Most likely, low levels of IAH, although able to reduce liver blood flow, are not per se sufficient to produce a real dysfunction; however, a correlation between the degree of IAH and the degree of hyperbilirubinemia exists. IAH does not seem to be an "on-off" phenomenon, but produces liver alterations for increasing levels of its severity.

Intra-abdominal hypertension in the critically ill: it is time to pay attention

PURPOSE OF THE REVIEW

There has been an exponentially increasing interest in intra-abdominal hypertension (IAH). Comparison of the published data however is difficult due to the lack of consensus definitions. This review will focus on the available literature from the last 2 years. A Medline and PubMed search was performed using 'intra-abdominal pressure' (IAP), 'intra-abdominal hypertension' (IAH), and 'abdominal compartment syndrome' (ACS) as search items. The aim was to find an answer to the question 'Isn't it time to pay attention to intra-abdominal pressure in the critically ill?'

RECENT FINDINGS

Although the number of studies published on this topic is steadily increasing and confirms the pathophysiologic implications of IAH on end-organ function within and outside the abdominal cavity it remains difficult to compare the literature data because the measurement methods and definitions used are not uniform. Provocative data have been published regarding the interactions between the abdominal and thoracic compartments especially in patients with capillary leak and fluid overload; most of this data raises even more questions than it gives answers and may therefore strengthen the nonbelievers who consider IAP, IAH and ACS as epiphenomena in critically ill patients. Unless the international scientific community does not come forward with clear-cut definitions we will keep comparing 'apples with oranges.'

SUMMARY

It is time to pay attention to intra-abdominal pressure in the critically ill. It is also time for standardized IAP measurement methods, good consensus definitions and randomized interventional studies.

Incidence and prognosis of intraabdominal hypertension in a mixed population of critically ill patients: a multiple-center epidemiological study

OBJECTIVE

Intraabdominal hypertension is associated with significant morbidity and mortality in surgical and trauma patients. The aim of this study was to assess, in a mixed population of critically ill patients, whether intraabdominal pressure at admission was an independent predictor for mortality and to evaluate the effects of intraabdominal hypertension on organ functions.

DESIGN

Multiple-center, prospective epidemiologic study.

SETTING

Fourteen intensive care units in six countries.

PATIENTS

A total of 265 consecutive patients admitted for >24 hrs during the 4-wk study period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Intraabdominal pressure was measured twice daily via the bladder. Data recorded on admission were the patient demographics with Simplified Acute Physiology Score II, Acute Physiology and Chronic Health Evaluation II score, and type of admission; during intensive care stay, Sepsis-Related Organ Failure Assessment score and intraabdominal pressure were measured daily together with fluid balance. Nonsurvivors had a significantly higher mean intraabdominal pressure on admission than survivors: 11.4 +/- 4.8 vs. 9.5 +/- 4.8 mm Hg. Independent predictors for mortality were age (odds ratio, 1.04; 95% confidence interval, 1.01-1.06; p = .003), Acute Physiology and Chronic Health Evaluation II score (odds ratio, 1.1; 95% confidence interval, 1.05-1.15; p < .0001), type of intensive care unit admission (odds ratio, 2.5 medical vs. surgical; 95% confidence interval, 1.24-5.16; p = .01), and the presence of liver dysfunction (odds ratio, 2.5; 95% confidence interval, 1.06-5.8; p = .04). The occurrence of intraabdominal hypertension during the intensive care unit stay was also an independent predictor of mortality (relative risk, 1.85; 95% confidence interval, 1.12-3.06; p = .01). Patients with intraabdominal hypertension at admission had significantly higher Sepsis-Related Organ Failure Assessment scores during the intensive care unit stay than patients without intraabdominal hypertension.

CONCLUSIONS

Intraabdominal hypertension on admission was associated with severe organ dysfunction during the intensive care unit stay. The mean intraabdominal pressure on admission was not an independent risk factor for mortality; however, the occurrence of intraabdominal hypertension during the intensive care unit stay was an independent outcome predictor.

Is it wise not to think about intraabdominal hypertension in the ICU?

PURPOSE OF REVIEW

This review focuses on the available literature published in the past 2 years. MEDLINE and PubMed searches were performed using intraabdominal pressure, intraabdominal hypertension, and abdominal compartment as search items. The aim was to find an answer to the question: "Is it wise not to measure or even not to think about intraabdominal hypertension in ICU?"

RECENT FINDINGS

It is difficult to find a good gold standard for intraabdominal pressure measurement. Bladder pressure can be used as an intraabdominal pressure estimate provided it is measured in a reproducible way. Automated continuous intraabdominal pressure monitoring has recently become available. Key messages are (1). body mass index and fluid resuscitation are independent predictors of intraabdominal hypertension; (2). intraabdominal hypertension increases intrathoracic, intracranial, and intracardiac filling pressures; (3). transmural or transabdominal filling pressures combined with volumetric parameters better reflect preload; (4). volumetric target values need to be corrected for baseline ejection fractions; (5). intraabdominal hypertension decreases left ventricular, chest wall and total respiratory system compliance; (6). best positive end-expiratory pressure can be set to counteract intraabdominal pressure; (7). acute respiratory distress syndrome definitions should take into account best positive end-expiratory pressure and intraabdominal pressure but not wedge pressure; (8). lung protective strategies should aim at deltaPplat (plateau pressure - intraabdominal pressure); (9). intraabdominal hypertension causes atelectasis and increases extravascular lung water; (10). intraabdominal hypertension is an independent predictor of acute renal failure; (11). monitoring of abdominal perfusion pressure can be useful; and (12). intraabdominal hypertension triggers bacterial translocation and multiple organ system failure.

SUMMARY

The answer is that it is unwise not to measure intraabdominal pressure in the ICU or even not to think about it.

Abdominal compartment syndrome: urological aspects

ACS is prevalent in various surgical conditions and in a large percentage of critically ill patients. Measuring the IAP is important in the early diagnosis of ACS and can be easily done by measuring the intravesical pressure. ACS adversely affects many organ systems; the pathogenesis of renal dysfunction is probably multifactorial, from a combination of reduced cardiac output, reduced GFR mediated by secretion of renin and angiotensin, aldosterone-mediated water reabsorption, increased renal parenchymal pressure and direct compression of the renal vein. Successful treatment requires a high index of suspicion, prompt recognition and early surgical abdominal decompression.