The Influence of Fluid Removal Using Continuous Venovenous Hemofiltration (CVVH) on Intra-abdominal Pressure and Kidney Function

University Hospital, Ghent

Overview

Intra- abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are a cause of organ dysfunction in critically ill patients. IAH develops due to abdominal lesions (primary IAH) or extra-abdominal processes (secondary IAH). Secondary IAH arises due to decreased abdominal wall compliance and gut edema caused by capillary leak and excessive fluid resuscitation. Decreasing intra-abdominal pressure (IAP) using decompressieve laparotomy has been shown to improve organ dysfunction. However, laparotomy is generally avoided in patients with secondary IAH due to the risk of abdominal complications. Acute kidney injury (AKI) is one of the first and most pronounced organ failures associated with IAH and many patients with AKI in the ICU require renal replacement therapy (RRT). Fluid removal using continuous RRT (CRRT) has been demonstrated to decrease IAP in small series and selected patients. The aim of this study is to evaluate whether fluid removal using CVVH in patients with IAH, fluid overload and AKI is feasible and whether it has a beneficial effect on organ dysfunction (compared to CVVH without net fluid removal).

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

SINGLE

Conditions

Critically Ill Intra-Abdominal Hypertension Abdominal Compartment Syndrome

Interventions

CVVHPROCEDURE

CVVH is started using following parameters: * Blood flow is started at 150 mL/min * Anticoagulation: none, heparin or low molecular weight heparin according to local protocols in study centers. * In both groups: dialysis dose of 25 mL/kg body weight administered using both pre- and postdilution * Substitution fluid temperature is started at 37°C and adjusted in function of patient body temperature (which is maintained at 35-37°C)

ultrafiltrationPROCEDURE

ultra filtration is started at 100 mL/h and increased according to following protocol * Ultrafiltration is increased by 100 mL/h after 2h and subsequently by 100mL/h (until a maximum of 500mL/h) every 4h unless: * Vasopressor or inotrope medication dose is increased by \> 25% (provided mean arterial pressure remains constant at 65 mmHg or another target value specified by treating physician according to standard of care) * When above condition is not met UF should be kept constant and a passive leg raising test or stroke volume variation measurement should be performed. If SVV \> 10% or PLR is positive 100mL of albumin 20% solution or 250 mL of Hydroxyethyl Starch 130/0.4 solution is administered according to treating physician at a maximum of 4 times per 24h * If there is no improvement after 2 colloid administration rounds, UF should be stopped for 4h and restarted at half the rate it was set at when discontinued.

ultrafiltration control groupPROCEDURE

ultrafiltration is set at 100 mL/h (and fluid administration is titrated to approach 100 mL /h)

Eligibility

Sex: ALLMin age: 18 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Adult patients (\>18y old) of either gender * Admitted to the ICU * Sedated and mechanically ventilated (and expected to remain so for at least 48h) * Informed consent given * admitted to the ICU for \<7 days or during the first 7 days of a new shock episode * AKI requiring RRT according to treating physician * IAP \>12mmHg being attributed to fluid overload by treating physician Exclusion Criteria: * Included in the same study before * Vasopressor and/or inotrope dose needed above noradrenaline 1µg/kg/min and dobutamine 10µg/kg/min * PaO2/FiO2 ratio \<100

Outcomes

Primary Outcomes

Change in IAP in patients receiving fluid removal during CVVH vs patients receiving CVVH without net fluid removal after 24 and 48h of CVVH treatment

Time frame: 24 and 48 hours

Secondary Outcomes

Difference between CVVH with fluid removal and CVVH without fluid removal

Difference in terms of * Need for vasopressor medication and hemodynamic parameters during the first seven days * PaO2/FiO2 (worst value over 24h daily first 7 days) * Volume of albumin solution or synthetic colloids administered during CVVH per 24h * SOFA score daily first seven days * Need for decompressive laparotomy or other means to decrease IAP * Acid-base status * Complications relating to ischemia

Time frame: after 24 hours and/or 7 days

Difference between both groups in terms of daily fluid balance

Time frame: during 7 days

The relationship between cumulative fluid balance at the start of each day of CVVH and the fluid balance achieved after 24h of CVVH with fluid removal

Time frame: 24 hours

Difference between both groups regarding recovery of renal function, need for RRT at discharge from the ICU and from the hospital

Time frame: discharge from ICU and hospital

Difference between both groups regarding mortality (28d, ICU and hospital) and ICU and hospital length of stay

Time frame: 28 days and length of stay in ICU and hospital