Effect of bladder volume on measured intravesical pressure: a prospective cohort study

INTRODUCTION: Correct bedside measurement of intra-abdominal pressure (IAP) is important. The bladder method is considered as the gold standard for indirect IAP measurement, but the instillation volumes reported in the literature vary substantially. The aim of this study was to evaluate the effect of instillation volume on intra-bladder pressure (IBP) as an estimation for IAP in critically ill patients. METHODS: In this prospective cohort study in 13 sedated and mechanically ventilated patients, we used a revised closed system repeated measurement technique for measurement of IBP. After the system was flushed, IBP was measured with 25 ml increments up to 300 ml. The absolute bias for each volume was calculated as IBP at a given volume minus IBP at zero volume. RESULTS: In total, 30 measurement sets were performed (mean 2.3 per patient). The median IBP at 25 ml was already significantly higher than IBP at zero volume (7.5 versus 6 mmHg). There was no correlation between IBP at zero volume and absolute IBP bias at any bladder volume. Median absolute IBP bias was 1.5 mmHg at 50 ml; 2.5 mmHg at 100 ml; 5.5 mmHg at 150 ml; and up to 11 mmHg at 300 ml. CONCLUSION: Larger instillation volumes than the usually recommended 50 ml to estimate IAP by bladder pressure may cause clinically relevant overestimation of IAP. Small volumes to a maximum of 25 ml, enough to create a fluid column and to remove air, may be sufficient

What every ICU clinician needs to know about the cardiovascular effects caused by abdominal hypertension

The effects of increased intra-abdominal pressure (IAP) on cardiovascular function are well recognized and include a combined negative effect on preload, afterload and contractility. The aim of this review is to summarize the current knowledge on this topic. The presence of intra-abdominal hypertension (IAH) erroneously increases barometric filling pressures like central venous (CVP) and pulmonary artery occlusion pressure (PAOP) (since these are zeroed against atmospheric pressure). Transmural filling pressures (calculated by subtracting the pleural pressure from the end-expiratory CVP value) may better reflect the true preload status but are difficult to obtain at the bedside. Alternatively, since pleural pressures are seldom measured, transmural CVP can also be estimated by subtracting half of the IAP from the end-expiratory CVP value, since abdominothoracic transmission is on average 50%. Volumetric preload indicators, such as global and right ventricular end-diastolic volumes or the left ventricular end-diastolic area, also correlate better with true preload. When using functional hemodynamic monitoring parameters like stroke volume variation (SVV) or pulse pressure variation (PPV) one must bear in mind that increased IAP will increase these values (via a concomitant increase in intrathoracic pressure). The passive leg raising test may be a false negative in IAH. Calculation of the abdominal perfusion pressure (as mean arterial pressure minus IAP) has been shown to be a better resuscitation endpoint than IAP alone. Finally, it is re-assuring that transpulmonary thermodilution techniques have been validated in the setting of IAH and abdominal compartment syndrome. In conclusion, the clinician must be aware of the different effects of IAH on cardiovascular function in order to assess the volume status accurately and to optimize hemodynamic performance

Decompressive laparotomy for abdominal compartment syndrome – a critical analysis

INTRODUCTION: Abdominal compartment syndrome (ACS) is increasingly recognized in critically ill patients, and the deleterious effects of increased intraabdominal pressure (IAP) are well documented. Surgical decompression through a midline laparotomy or decompressive laparotomy remains the sole definite therapy for ACS, but the effect of decompressive laparotomy has not been studied in large patient series. METHODS: We reviewed English literature from 1972 to 2004 for studies reporting the effects of decompressive laparotomy in patients with ACS. The effect of decompressive laparotomy on IAP, patient outcome and physiology were analysed. RESULTS: Eighteen studies including 250 patients who underwent decompressive laparotomy could be included in the analysis. IAP was significantly lower after decompression (15.5 mmHg versus 34.6 mmHg before, p < 0.001), but intraabdominal hypertension persisted in the majority of the patients. Mortality in the whole group was 49.2% (123/250). The effect of decompressive laparotomy on organ function was not uniform, and in some studies no effect on organ function was found. Increased PaO(2)/FIO(2 )ratio (PaO(2 )= partial pressure of oxygen in arterial blood, FiO(2 )= fraction of inspired oxygen) and urinary output were the most pronounced effects of decompressive laparotomy. CONCLUSION: The effects of decompressive laparotomy have been poorly investigated, and only a small number of studies report its effect on parameters of organ function. Although IAP is consistently lower after decompression, mortality remains considerable. Recuperation of organ dysfunction after decompressive laparotomy for ACS is variable

The use of bio-electrical impedance analysis (BIA) to guide fluid management, resuscitation and deresuscitation in critically ill patients : a bench-to-bedside review

The impact of a positive fluid balance on morbidity and mortality has been well established. However, little is known about how to monitor fluid status and fluid overload. This narrative review summarises the recent literature and discusses the different parameters related to bio-electrical impedance analysis (BIA) and how they might be used to guide fluid management in critically ill patients. Definitions are listed for the different parameters that can be obtained with BIA; these include among others total body water (TBW), intracellular water (ICW), extracellular water (ECW), ECW/ICW ratio and volume excess (VE). BIA allows calculation of body composition and volumes by means of a current going through the body considered as a cylinder. Reproducible measurements can be obtained with tetrapolar electrodes with two current and two detection electrodes placed on hands and feet. Modern devices also apply multiple frequencies, further improving the accuracy and reproducibility of the results. Some pitfalls and conditions are discussed that need to be taken into account for correct BIA interpretation. Although BIA is a simple, noninvasive, rapid, portable, reproducible, and convenient method of measuring body composition and fluid distribution with fewer physical demands than other techniques, it is still unclear whether it is sufficiently accurate for clinical use in critically ill patients. However, the potential clinical applications are numerous. An overview regarding the use of BIA parameters in critically ill patients is given, based on the available literature. BIA seems a promising tool if performed correctly. It is non-invasive and relatively inexpensive and can be performed at bedside, and it does not expose to ionising radiation. Modern devices have very limited between-observer variations, but BIA parameters are population-specific and one must be aware of clinical situations that may interfere with the measurement such as visible oedema, nutritional status, or fluid and salt administration. BIA can help guide fluid management, resuscitation and de-resuscitation. The latter is especially important in patients not progressing spontaneously from the Ebb to the Flow phase of shock. More research is needed in critically ill patients before widespread use of BIA can be suggested in this patient population.The impact of a positive fluid balance on morbidity and mortality has been well established. However, little is known about how to monitor fluid status and fluid overload. This narrative review summarises the recent literature and discusses the different parameters related to bio-electrical impedance analysis (BIA) and how they might be used to guide fluid management in critically ill patients. Definitions are listed for the different parameters that can be obtained with BIA; these include among others total body water (TBW), intracellular water (ICW), extracellular water (ECW), ECW/ICW ratio and volume excess (VE). BIA allows calculation of body composition and volumes by means of a current going through the body considered as a cylinder. Reproducible measurements can be obtained with tetrapolar electrodes with two current and two detection electrodes placed on hands and feet. Modern devices also apply multiple frequencies, further improving the accuracy and reproducibility of the results. Some pitfalls and conditions are discussed that need to be taken into account for correct BIA interpretation. Although BIA is a simple, noninvasive, rapid, portable, reproducible, and convenient method of measuring body composition and fluid distribution with fewer physical demands than other techniques, it is still unclear whether it is sufficiently accurate for clinical use in critically ill patients. However, the potential clinical applications are numerous. An overview regarding the use of BIA parameters in critically ill patients is given, based on the available literature. BIA seems a promising tool if performed correctly. It is non-invasive and relatively inexpensive and can be performed at bedside, and it does not expose to ionising radiation. Modern devices have very limited between-observer variations, but BIA parameters are population-specific and one must be aware of clinical situations that may interfere with the measurement such as visible oedema, nutritional status, or fluid and salt administration. BIA can help guide fluid management, resuscitation and de-resuscitation. The latter is especially important in patients not progressing spontaneously from the Ebb to the Flow phase of shock. More research is needed in critically ill patients before widespread use of BIA can be suggested in this patient population

Awareness and knowledge of intra-abdominal hypertension and abdominal compartment syndrome: results of an international survey

Background: Surveys have demonstrated a lack of physician awareness of intra-abdominal hypertension and abdominal compartment syndrome (IAH/ACS) and wide variations in the management of these conditions, with many intensive care units (ICUs) reporting that they do not measure intra-abdominal pressure (IAP). We sought to determine the association between publication of the 2006/2007 World Society of the Abdominal Compartment Syndrome (WSACS) Consensus Definitions and Guidelines and IAH/ACS clinical awareness and management. Methods: The WSACS Executive Committee created an interactive online survey with 53 questions, accessible from November 2006 until December 2008. The survey was endorsed by the WSACS, the European Society of Intensive Care Medicine (ESICM) and the Society of Critical Care Medicine (SCCM). A link to the survey was emailed to all members of the supporting societies. Participants of the 3rd World Congress on Abdominal Compartment Syndrome meeting (March 2007, Antwerp, Belgium) were also asked to complete the questionnaire. No reminders were sent. Based on 13 knowledge questions, an overall score was calculated (expressed as percentage). Results: A total of 2,244 of the approximately 10,000 clinicians who were sent the survey responded (response rate: 22.4%). Most of the 2,244 respondents (79.2%) completing the survey were physicians or physicians in training and the majority were residing in North America (53.0%). The majority of responders (85%) were familiar with IAP/IAH/ACS, but only 28% were aware of the WSACS consensus definitions for IAH/ACS. Three quarters of respondents considered the cut-off for IAH to be at least 15 mm Hg, and nearly two thirds believed the cut-off for ACS was higher than the currently suggested consensus definition (20 mm Hg). In 67.8% of respondents, organ dysfunction was only considered a problem with IAP of 20 mm Hg or higher. IAP was measured most frequently via the bladder (91.9%), but the majority reported that they instilled volumes well above the current guidelines. Surgical decompression was frequently used to treat IAH/ACS, whereas medical management was only attempted by about half of the respondents. Decisions to decompress the abdomen were predominantly based on the severity of IAP elevation and presence of organ dysfunction (74.4%). Overall knowledge scores were low (43 +/- 15%); respondents who were aware of the WSACS had a better score compared to those who were not (49.6% vs 38.6%, P < 0.001). Conclusions: This survey showed that although most responding clinicians claim to be familiar with IAH and ACS, knowledge of published consensus definitions, measurement techniques, and clinical management is inadequate

The significance of intra-abdominal pressure in neurosurgery and neurological diseases : a narrative review and a conceptual proposal

Intra-abdominal pressure (IAP) is a physiological parameter that has gained considerable attention during the last few decades. The incidence of complications arising from increased IAP, known as intra-abdominal hypertension (IAH) or abdominal compartment syndrome in critically ill patients, is high and its impact is significant. The effects of IAP in neurological conditions and during surgical procedures are largely unexplored. IAP also appears to be relevant during neurosurgical procedures (spine and brain) in the prone position, and in selected cases, IAH may affect cerebrospinal fluid drainage after a ventriculoperitoneal shunt operation. Furthermore, raised IAP is one of the contributors to intracranial hypertension in patients with morbid obesity. In traumatic brain injury, case reports described how abdominal decompression lowers intracerebral pressure. The anatomical substrate for transmission of the IAP to the brain and venous system of the spine is the extradural neural axis compartment; the first reports of this phenomenon can be found in anatomical studies of the sixteenth century. In this review, we summarize the available knowledge on how IAP impacts the cerebrospinal venous system and the jugular venous system via two pathways, and we discuss the implications for neurosurgical procedures as well as the relevance of IAH in neurological disorders

Cytokine removal in human septic shock : where are we and where are we going?

Although improving, the mortality from septic shock still remains high despite increased international awareness. As a consequence, much effort has focused on alternative treatment strategies in an effort to improve outcomes. The application of blood purification therapies to improve immune homeostasis has been suggested as one such method, but these approaches, such as high-volume continuous haemofiltration or cytokine and/or endotoxin removal, have enjoyed little success to date. More recently, the use of sorbent technologies has attracted much attention. These adsorbers are highly effective at removing inflammatory mediators, in particular, cytokines, from the bloodstream. This narrative review is the executive summary of meetings held throughout the 6th International Fluid Academy Days in Antwerp, Belgium (Nov 23-25, 2017), focusing on the current understanding regarding the use of such adsorbers in humans with septic shock. We followed a modified Delphi approach involving a combination of evidence appraisal together with expert opinion in order to achieve recommendations for practice and, importantly, future research