Inneke De laet

Intra-abdominal Hypertension and Abdominal Compartment Syndrome.

Increased intra-abdominal pressure (IAP), also referred to as intra-abdominal hypertension (IAH), affects organ function in critically ill patients and may lead to abdominal compartment syndrome (ACS). Although initially described in surgical patients, IAH and ACS also occur in medical patients without abdominal conditions. IAP can be measured easily and reliably in patients through the bladder using simple tools. The effects of increased IAP are multiple, but the kidney is especially vulnerable to increased IAP because of its anatomic position. Although the means by which kidney function is impaired in patients with ACS is incompletely elucidated, available evidence suggests that the most important factor involves alterations in renal blood flow. IAH should be considered as a potential cause of acute kidney injury in critically ill patients; its role in other conditions, such as hepatorenal syndrome, remains to be elucidated. Because several treatment options (both medical and surgical) are available, IAH and ACS should no longer be considered irrelevant epiphenomena of severe illness or critical care. An integrated approach targeting IAH may improve outcomes and decrease hospital costs, and IAP monitoring is a first step toward dedicated IAH management. IAH prevention, most importantly during abdominal surgery but also during fluid resuscitation, may avoid ACS altogether. However, when ACS occurs and medical treatment fails, decompressive laparotomy is the only option.

The impact of body position on intra-abdominal pressure measurement: a multicenter analysis.

Objective: Elevated intra-abdominal pressure (IAP) is a frequent cause of morbidity and mortality among the critically ill. IAP is most commonly measured using the intravesicular or “bladder” technique. The impact of changes in body position on the accuracy of IAP measurements, such as head of bed elevation to reduce the risk of ventilator-associated pneumonia, remains unclear. Design: Prospective, cohort study. Setting: Twelve international intensive care units. Patients: One hundred thirty-two critically ill medical and surgical patients at risk for intra-abdominal hypertension and abdominal compartment syndrome. Interventions: Triplicate intravesicular pressure measurements were performed at least 4 hours apart with the patient in the supine, 15°, and 30° head of bed elevated positions. The zero reference point was the mid-axillary line at the iliac crest. Measurements and Main Results: Mean IAP values at each head of bed position were significantly different (p < 0.0001). The bias between IAPsupine and IAP15° was 1.5 mm Hg (1.3–1.7). The bias between IAPsupine and IAP30° was 3.7 mm Hg (3.4–4.0). Conclusions: Head of bed elevation results in clinically significant increases in measured IAP. Consistent body positioning from one IAP measurement to the next is necessary to allow consistent trending of IAP for accurate clinical decision making. Studies that involve IAP measurements should describe the patient’s body position so that these values may be properly interpreted.

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

Background and aimsThe 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 contentsThis 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.ConclusionsThe 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: evolving concepts.

This article focuses primarily on the recent literature on abdominal compartment syndrome (ACS) and the definitions and recommendations published by the World Society for the Abdominal Compartment Syndrome. The definitions regarding increased intra-abdominal pressure (IAP) are listed and are followed by an overview of the different mechanisms of organ dysfunction associated with intra-abdominal hypertension (IAH). Measurement techniques for IAP are discussed, as are recommendations for organ function support and options for treatment in patients who have IAH. ACS was first described in surgical patients who had abdominal trauma, bleeding, or infection; but recently, ACS has been described in patients who have other pathologies. This article intends to provide critical care physicians with a clear insight into the current state of knowledge regarding IAH and ACS.

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

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

Can the abdominal perimeter be used as an accurate estimation of intra-abdominal pressure?

Introduction:Intra-abdominal pressure (IAP) is an important parameter and prognostic indicator of the patient’s underlying physiologic status. Correct IAP measurement, therefore, is crucial. Most of the direct and indirect techniques are not free from risks and require some time and skills. This study looks at the possibility of using the abdominal perimeter (AP) as a quick estimation for IAP. Methods:In total, 237 paired measurements were performed in 26 intensive care unit patients. The IAP was measured according to the recommendations of the World Society on Abdominal Compartment Syndrome via an indwelling bladder catheter using a pressure transducer. The AP was defined as the abdominal circumference at its largest point using body marks as reference for consecutive measurements. Results:The male:female ratio was 1:1, age 69.8 ± 15.2 yrs, Acute Physiology and Chronic Health Evaluation II score 26.5 ± 9.2, and Simplified Acute Physiology Score II score 58 ± 15.5. The number of measurements in each patient was 9.4 ± 4.6. The IAP was 10.8 ± 4.9 mm Hg, and the AP was 101 ± 19.2 cm. There was a poor but statistically significant correlation between IAP and AP: AP = 1.8 × IAP + 81.6 (R2 = 0.21, p = 0.04), but the bias was considerable. The correlation was somewhat better between &Dgr;IAP (the difference between two consecutive IAP measurements) and &Dgr;AP (the difference between two consecutive AP measurements) in 210 paired measurements: &Dgr;AP = 0.4 × &Dgr;IAP + 0.1 (R2 = 0.24, p < 0.0001). The analysis according to Bland and Altman showed that &Dgr;IAP was almost identical to &Dgr;AP with a mean difference or bias of 0 ± 3 (95% confidence interval: −0.4 to 0.4); however, the limits of agreement were large and thus reflect poor agreement. Conclusions:In view of the poor correlation between IAP and AP, the latter cannot be used as a clinical estimate for IAP. The correlation between &Dgr;IAP and &Dgr;AP was somewhat better, meaning that &Dgr;AP can be used as an estimate of the evolution of IAP over time; however, for making a definite diagnosis of intra-abdominal hypertension or abdominal compartment syndrome, the exact value of IAP needs to be measured.

IAH/ACS: The Rationale for Surveillance

Surveillance for intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) should be implemented in every intensive care unit (ICU), because it has been demonstrated that surveillance is effective. Several criteria that have led to the conclusion that IAH/ACS monitoring is of value: First, IAH is a frequent problem in critically ill patients that directly affects function of all organ systems to some degree, and that is associated with considerable mortality. Furthermore, simple tools for intra-abdominal pressure (IAP) monitoring are available, and it can be safely applied without the need for advanced tools. Finally, both ACS and IAH can be treated with either medical or surgical interventions. Treatment for IAH/ACS should be selected on the basis of the severity of symptoms and the cause of IAH. IAP monitoring should also be incorporated in the daily ICU management of the patient.

AIDS is coming to your ICU: be prepared for acute bowel injury and acute intestinal distress syndrome...

In this issue of Intensive Care Medicine, Reintam et al. report the results of a study entitled ‘‘Primary and secondary intra-abdominal hypertension—different impact on ICU outcome’’ [1]. The authors collected prospective data on 257 mechanically ventilated critically ill patients with more than two risk factors for IAH (about one-third of the entire ICU population). The authors found that IAH (defined as a sustained increase in intraabdominal pressure (IAP) equal to or above 12 mmHg) was present on admission in 23.4% of cases, while a total of 37% developed IAH within 5 days of whom 4.7% developed ACS. Primary IAH (with an underlying cause within the abdomino-pelvic region) was seen in 63.2% of patients with IAH. Patients with secondary IAH demonstrated a different time course with a significant increase of mean IAP during the first 3 days (mean DIAP was 2.2 ± 4.7 mmHg), whilst in the patients with primary IAH, IAP decreased (mean DIAP -1.1 ± 3.7 mmHg). Patients with IAH were sicker, had more organ failure and a higher ICU (37.9 vs. 19.1%; P = 0.001), 28-day (48.4 vs. 27.8%; P = 0.001), and 90-day mortality (53.7 vs. 35.8%; P = 0.004) compared to patients with a normal IAP. Patients with secondary IAH had a significantly higher ICU mortality than patients with primary IAH (P = 0.032). The development of IAH during ICU stay was an independent risk factor for death (OR 2.52; 95% CI 1.23–5.14). Therefore, ICU physicians no longer have an excuse not to obtain a baseline IAP value in patients with two or more risk factors for IAH [2, 3].

Nexfin noninvasive continuous hemodynamic monitoring: validation against continuous pulse contour and intermittent transpulmonary thermodilution derived cardiac output in critically ill patients.

Introduction. Nexfin (Bmeye, Amsterdam, Netherlands) is a noninvasive cardiac output (CO) monitor based on finger arterial pulse contour analysis. The aim of this study was to validate Nexfin CO (NexCO) against thermodilution (TDCO) and pulse contour CO (CCO) by PiCCO (Pulsion Medical Systems, Munich, Germany). Patients and Methods. In a mix of critically ill patients (n = 45), NexCO and CCO were measured continuously and recorded at 2-hour intervals during the 8-hour study period. TDCO was measured at 0–4–8 hrs. Results. NexCO showed a moderate to good (significant) correlation with TDCO (R 2 0.68, P < 0.001) and CCO (R 2 0.71, P < 0.001). Bland and Altman analysis comparing NexCO with TDCO revealed a bias (± limits of agreement, LA) of 0.4 ± 2.32 L/min (with 36% error) while analysis comparing NexCO with CCO showed a bias (±LA) of 0.2 ± 2.32 L/min (37% error). NexCO is able to follow changes in TDCO and CCO during the same time interval (level of concordance 89.3% and 81%). Finally, polar plot analysis showed that trending capabilities were acceptable when changes in NexCO (ΔNexCO) were compared to ΔTDCO and ΔCCO (resp., 89% and 88.9% of changes were within the level of 10% limits of agreement). Conclusion. we found a moderate to good correlation between CO measurements obtained with Nexfin and PiCCO.

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

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