Intra-abdominal hypertension and hypoxic respiratory failure together predict adverse outcome - A sub-analysis of a prospective cohort.

PURPOSE: To assess whether the combination of intra-abdominal hypertension (IAH, intra-abdominal pressure ≥ 12 mmHg) and hypoxic respiratory failure (HRF, PaO2/FiO2 ratio < 300 mmHg) in patients receiving invasive ventilation is an independent risk factor for 90- and 28-day mortality as well as ICU- and ventilation-free days. METHODS: Mechanically ventilated patients who had blood gas analyses performed and intra-abdominal pressure measured, were included from a prospective cohort. Subgroups were defined by the absence (Group 1) or the presence of either IAH (Group 2) or HRF (Group 3) or both (Group 4). Mixed-effects regression analysis was performed. RESULTS: Ninety-day mortality increased from 16% (Group 1, n = 50) to 30% (Group 2, n = 20) and 27% (Group 3, n = 100) to 49% (Group 4, n = 142), log-rank test p < 0.001. The combination of IAH and HRF was associated with increased 90- and 28-day mortality as well as with fewer ICU- and ventilation-free days. The association with 90-day mortality was no longer present after adjustment for independent variables. However, the association with 28-day mortality, ICU- and ventilation-free days persisted after adjusting for independent variables. CONCLUSIONS: In our sub-analysis, the combination of IAH and HRF was not independently associated with 90-day mortality but independently increased the odds of 28-day mortality, and reduced the number of ICU- and ventilation-free days.

Non-invasive indirect monitoring of intra-abdominal pressure using microwave reflectometry: system design and proof-of-concept clinical trial.

Monitoring intra-abdominal pressure (IAP) has become a standard in intensive care units. Correlation between the abdominal wall's thickness (AWTh) and IAP has been reported previously. The abdominal wall can be modeled as a compound of parallel dielectric slabs; changes in their width have a direct effect on the reflection coefficient of the abdominal wall at microwave frequencies. This work describes the design of a reflectometry system and its proof-of-concept trial on five patients during laparoscopic surgery. The system complies with IEEE Std. C95.1-2005 concerning exposure of humans to microwave electromagnetic fields in controlled environments. The results putatively show an inverse correlation between IAP and the reflection coefficient, and a strong dependence on the body mass index. A better understanding of the dynamics in the changes of the AWTh (during intra-abdominal hypertension) will allow further development of a microwave-based technique for the continuous non-invasive indirect monitoring of IAP in critical patients.

Optimized electrical bioimpedance measurements of abdominal wall on a porcine model for the continuous non-invasive assessment of intra-abdominal pressure.

This work describes the optimization of electrical bioimpedance measurements for indirect intra-abdominal pressure (IAP) assessment. The experimental run was performed on a female Sus scrofa domesticus (domestic pig). Different values of IAP were induced by inflation of the abdominal cavity, using a trocar placed near the umbilicus over the linea alba. The whole experiment was run within 1 h of the subject being sacrificed. The abdominal wall thickness was measured at an IAP of 5 mmHg. An exponential trend linking between the bioimpedance values at 99.8 kHz and the IAP was found. Non-optimized electrode placement presented a strongly reduced sensitivity to IAP changes above 7 mmHg. Upon optimization and placing the electrodes with a separation of about 3.6 times the measured abdominal wall thickness, the sensitivity for high IAP drastically increased, allowing continuous non-invasive monitoring of IAP, confirming the optimization method proposed in this work.

The role of abdominal compliance, the neglected parameter in critically ill patients - a consensus review of 16. Part 1: definitions and pathophysiology.

Over the last few decades, increasing attention has been paid to understanding the pathophysiology, aetiology, prognosis, and treatment of elevated intra-abdominal pressure (IAP) in trauma, surgical, and medical patients. However, there is presently a relatively poor understanding of intra-abdominal volume (IAV) and the relationship between IAV and IAP (i.e. abdominal compliance). Consensus definitions on Cab were discussed during the 5th World Congress on Abdominal Compartment Syndrome and a writing committee was formed to develop this article. During the writing process, a systematic and structured Medline and PubMed search was conducted to identify relevant studies relating to the topic. According to the recently updated consensus definitions of the World Society on Abdominal Compartment Syndrome (WSACS), abdominal compliance (Cab) is defined as a measure of the ease of abdominal expansion, which is determined by the elasticity of the abdominal wall and diaphragm. It should be expressed as the change in IAV per change in IAP (mL [mm Hg]⁻¹). Importantly, Cab is measured differently than IAP and the abdominal wall (and its compliance) is only a part of the total abdominal pressure-volume (PV) relationship. During an increase in IAV, different phases are encountered: the reshaping, stretching, and pressurisation phases. The first part of this review article starts with a comprehensive list of the different definitions related to IAP (at baseline, during respiratory variations, at maximal IAV), IAV (at baseline, additional volume, abdominal workspace, maximal and unadapted volume), and abdominal compliance and elastance (i.e. the relationship between IAV and IAP). An historical background on the pathophysiology related to IAP, IAV and Cab follows this. Measurement of Cab is difficult at the bedside and can only be done in a case of change (removal or addition) in IAV. The Cab is one of the most neglected parameters in critically ill patients, although it plays a key role in understanding the deleterious effects of unadapted IAV on IAP and end-organ perfusion. The definitions presented herein will help to understand the key mechanisms in relation to Cab and clinical conditions and should be used for future clinical and basic science research. Specific measurement methods, guidelines and recommendations for clinical management of patients with low Cab are published in a separate review.

The role of abdominal compliance, the neglected parameter in critically ill patients - a consensus review of 16. Part 2: measurement techniques and management recommendations.

The recent definitions on intra-abdominal pressure (IAP), intra-abdominal volume (IAV) and abdominal compliance (Cab) are a step forward in understanding these important concepts. They help our understanding of the pathophysiology, aetiology, prognosis, and treatment of patients with low Cab. However, there is still a relatively poor understanding of the different methods used to measure IAP, IAV and Cab and how certain conditions may affect the results. This review will give a concise overview of the different methods to assess and estimate Cab; it will list important conditions that may affect baseline values and suggest some therapeutic options. Abdominal compliance (Cab), defined as a measure of the ease of abdominal expansion, is measured differently than IAP. The compliance of the abdominal wall is only a part of the total abdominal pressure-volume (PV) relationship. Measurement or estimation of Cab is difficult at the bedside and can only be done in a case of change (removal or addition) in IAV. The different measurement techniques will be discussed in relation to decreases (ascites drainage, haematoma evacuation, gastric suctioning) or increases in IAV (gastric insufflation, laparoscopy with CO2 pneumoperitoneum, peritoneal dialysis). More specific techniques using the interactions between the thoracic and abdominal compartment during positive pressure ventilation will also be discussed (low flow PV loop, respiratory IAP variations, respiratory abdominal variation test, mean IAP and abdominal pressure variation), together with the concept of the polycompartment model. The relation between IAV and IAP is linear at low IAV and becomes curvilinear and exponential at higher volumes. Specific conditions in relation to increased (previous pregnancy or laparoscopy, gynoid fat distribution, ellipse-shaped internal abdominal perimeter) or decreased Cab (obesity, fluid overload, android fat distribution, sphere-shaped internal abdominal perimeter) will be discussed as well as their impact on baseline IAV, IAP, reshaping capacity and abdominal workspace volume. Finally, we suggest possible treatment options in situations of unadapted IAV according to existing Cab, which results in high IAP. A large overlap exists between the treatment of patients with abdominal hypertension and those with low Cab. The Cab plays a key role in understanding the deleterious effects of unadapted IAV on IAP and end-organ perfusion and function. If we can identify patients with low Cab, we can anticipate and select the most appropriate surgical treatment to avoid complications such as IAH or ACS.

ABDOPRE: dispositivo de aplicação externa para redução da pressão intra-abdominal: Experiencia clínica preliminar / ABDOPRE: dispositivo de aplicación externa para reducción de presión intraabdominal: Preliminary clinical experience / ABDOPRE: an external device for the reduction of intra-abdominal pressure

São descritos os objetivos de redução da pressão intra-abdominal e o projeto de um dispositivo que os atenda. O ABDO-PRE compreende, pela primeira vez, um mecanismo de servo-controle de aplicação externa que mede a pressão intravesical como variável de controle. São apresentados os resultados da aplicação em 4 pacientes com hipertensão intra-abdominal, produzindo uma redução de 16 por cento a 35 por cento em três casos e um aumento paradoxal da pressão em um dos casos, devido a um desajuste entre a geometria da câmara de vácuo e a alteração anatômica acarretada pela obesidade da paciente. Estes resultados são promissores em relação ao possível uso do ABDOPRE na prática clínica para redução da hipertensão intra-abdominal.

Se describen los objetivos de reducción de la presión intraabdominal y el proyecto de un dispositivo que los cumpla. ABDOPRE comprende por primera vez un mecanismo servcocontrolado de aplicación externa que toma la presión intravesical como variable de control. Se presenta el resultado de la aplicación en 4 pacientes afectados por hipertensión intraabdominal, con el resultado de una reducción de entre 16 por ciento y 35 por ciento en tres casos y de un aumento paradojal de presión en un caso debido a desajuste de la geometría de la campana de vacío a la anatomía obesa del paciente. Estos resultados prometen el posible uso de ABDOPRE para la reducción de la hipertensión intraabdominal en la práctica clínica.

This article describes a device for the reduction of intra-abdominal pressure. The device (ABDOPRE) includes a unique external servo-control mechanism, based on urinary bladder pressure measurement. The results of ABDOPRE use in the first four intra-abdominal hypertension patients are reported; the device resulted in a reduction of intra-abdominal pressure between 16 percent and 35 percent in 3 cases and in a paradoxical increase of the intra-abdominal pressure in an obese woman, likely due to inappropriate chamber size for the patient's anatomy. These results are promising and ABDOPRE may be useful in clinical practice.

ABDOPRE: an external device for the reduction of intra-abdominal pressure. / ABDOPRE: dispositivo de aplicação externa para redução da pressão intra-abdominal: Experiencia clínica preliminar.

This article describes a device for the reduction of intra-abdominal pressure. The device (ABDOPRE) includes a unique external servo-control mechanism, based on urinary bladder pressure measurement. The results of ABDOPRE use in the first four intra-abdominal hypertension patients are reported; the device resulted in a reduction of intra-abdominal pressure between 16% and 35% in 3 cases and in a paradoxical increase of the intra-abdominal pressure in an obese woman, likely due to inappropriate chamber size for the patient's anatomy. These results are promising and ABDOPRE may be useful in clinical practice.

Direct measurement of intra-abdominal pressure with a solid microtranducer.

OBJECTIVE: To describe a direct intra-abdominal pressure (IAP) measurement technique using a solid microsensor comparing its values with the ones simultaneously obtained by means of Kron's technique. Comparative study between two different methods to measure intra-abdominal pressure in a multidisciplinary intensive care unit of a university hospital. METHODS: In 11 critical patients considered irreversibly ill, IAP was simultaneously measured via Kron's technique (IAPK) and by direct measure (IAPC) through an abdominal tap with a Codman microsensor, inserted through it. Several measurements were obtained at different PEEP levels (0, 10 and 20 cm of H20) and bed inclination (0 degrees , 40 degrees and 60 degrees ). RESULTS: 92 simultaneous measurements of IAPK and IAPC were made. The difference between both measurements (mean +/- SD) were: 0.286 +/- 0.938 mmHg. The correlation coefficient was r = 0.98. Bland-Altman plot showed a narrow distribution: 95% of the differences were between 1.87 mmHg of each averaged value. No complications with IAPC measurements were found. CONCLUSIONS: Direct IAP measurement with a Codman microsensor allows continuous monitoring without urinary tract manipulation, is simple to use and to calibrate, minimally invasive and appropriate for patients at risk to develop abdominal compartmental syndrome. Due to its cost it should be reserved for selected critical patients where standard techniques are contraindicated or can be inaccurate.