The pathophysiological impact of intra-abdominal hypertension in pigs

Intestinal oxygen utilisation and cellular adaptation during intestinal ischaemia-reperfusion injury

The gastrointestinal tract can be deranged by ailments including sepsis, trauma and haemorrhage. Ischaemic injury provokes a common constellation of microscopic and macroscopic changes that, together with the paradoxical exacerbation of cellular dysfunction and death following restoration of blood flow, are collectively known as ischaemia-reperfusion injury (IRI). Although much of the gastrointestinal tract is normally hypoxemic, intestinal IRI results when there is inadequate oxygen availability due to poor supply (pathological hypoxia) or abnormal tissue oxygen use and metabolism (dysoxia). Intestinal oxygen uptake usually remains constant over a wide range of blood flows and pressures, with cellular function being substantively compromised when ischaemia leads to a >50% decline in intestinal oxygen consumption. Restoration of perfusion and oxygenation provokes additional injury, resulting in mucosal damage and disruption of intestinal barrier function. The primary cellular mechanism for sensing hypoxia and for activating a cascade of cellular responses to mitigate the injury is a family of heterodimer proteins called hypoxia-inducible factors (HIFs). The HIF system is connected to numerous biochemical and immunologic pathways induced by IRI and the concentration of those proteins increases during hypoxia and dysoxia. Activation of the HIF system leads to augmented transcription of specific genes in various types of affected cells, but may also augment apoptotic and inflammatory processes, thus aggravating gut injury. KEY POINTS: During intestinal ischaemia, mitochondrial oxygen uptake is reduced when cellular oxygen partial pressure decreases to below the threshold required to maintain normal oxidative metabolism. Upon reperfusion, intestinal hypoxia may persist because microcirculatory flow remains impaired and/or because available oxygen is consumed by enzymes, intestinal cells and neutrophils.

Intra-abdominal pressure and residual renal function decline in peritoneal dialysis: a threshold-based investigation

BACKGROUND

The potential impact of elevated intra-abdominal pressure (IAP) on residual renal function (RRF) has not been determined. The objective of this study was to investigate the relationship between IAP and the rate of RRF decline in newly initiated peritoneal dialysis (PD) patients, and to identify the optimal IAP threshold value for delaying the deterioration of RRF.

METHODS

A cohort of 62 newly initiated PD patients who completed both 6- and 12-month follow-up evaluations was obtained using the Durand method. A logistic regression model was used to identify variables associated with a rapid decline in RRF. Receiver operating characteristic (ROC) curves were generated to determine the optimal threshold value. Another retrospective cohort analysis was performed to validate the identified critical value.

RESULTS

For each 1 cmH2O increase in IAP, the risk of a rapid decline in the RRF increased by a factor of 1.679. Subsequent analysis revealed that patients in the high IAP group had more significant decreases in residual renal estimated glomerular filtration rate (eGFR) (Z = -3.694, p < 0.001) and urine volume (Z = -3.121, p < 0.001) than did those in the non-high IAP group. Furthermore, an IAP ≥15.65 cmH2O was a robust discriminator for the prediction of the rate of RRF decline.

CONCLUSION

Patients in the high IAP group experienced a more rapid decline in RRF. Additionally, an optimal critical pressure of 15.65 cmH2O was identified for predicting the rate of RRF decline. IAP, as one of the factors contributing to the rapid decline in RRF in the first year of PD, should be given due attention.

International cross-sectional survey on current and updated definitions of intra-abdominal hypertension and abdominal compartment syndrome

BACKGROUND

The Abdominal Compartment Society (WSACS) established consensus definitions and recommendations for the management of intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) in 2006, and they were last updated in 2013. The WSACS conducted an international survey between 2022 and 2023 to seek the agreement of healthcare practitioners (HCPs) worldwide on current and new candidate statements that may be used for future guidelines.

METHODS

A self-administered, online cross-sectional survey was conducted under the auspices of the WSACS to assess the level of agreement among HCPs over current and new candidate statements. The survey, distributed electronically worldwide, collected agreement or disagreement with statements on the measurement of intra-abdominal pressure (IAP), pathophysiology, definitions, and management of IAH/ACS. Statistical analysis assessed agreement levels, expressed in percentages, on statements among respondents, and comparisons between groups were performed according to the respondent's education status, base specialty, duration of work experience, role (intensivist vs non-intensivist) and involvement in previous guidelines. Agreement was considered to be reached when 80% or more of the respondents agreed with a particular statement.

RESULTS

A total of 1042 respondents from 102 countries, predominantly physicians (73%), of whom 48% were intensivists, participated. Only 59% of HCPs were aware of the 2013 WSACS guidelines, and 41% incorporated them into practice. Despite agreement in most statements, significant variability existed. Notably, agreement was not reached on four new candidate statements: "normal intra-abdominal pressure (IAP) is 10 mmHg in critically ill adults" (77%), "clinical assessment and estimation of IAP is inaccurate" (65.2%), "intragastric can be an alternative to the intravesical route for IAP measurement" (70.4%), and "measurement of IAP should be repeated in the resting position after measurement in a supine position" (71.9%). The survey elucidated nuances in clinical practice and highlighted areas for further education and standardization.

CONCLUSION

More than ten years after the last published guidelines, this worldwide cross-sectional survey collected feedback and evaluated the level of agreement with current recommendations and new candidate statements. This will inform the consensus process for future guideline development.