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The gold standard to measure intra-abdominal pressure (IAP) is intra-vesical measurement via the urinary bladder. However, this technique is restricted in ambulatory settings because of the risk of iatrogenic urinary tract infections. Rectal IAP measurements (IAP(rect)) may overcome these limitations, but requires validation. This validation study compares the IAP(rect) technique against gold standard intra-vesical IAP measurements (IAP(ves)). IAP(rect) using an air-filled balloon catheter and IAP(ves) using Foley Manometer Low Volume were measured simultaneously in sedated and ventilated patients. Measurements were performed twice in different positions (supine and HOB 45 degrees elevated head of bed) and with an external abdominal pressure belt. Sixteen patients were included. Seven were not eligible for analysis due to unreliable IAP(rect) values. IAP(rect) was significantly higher than IAP(ves) for all body positions (p < 0.01) and the correlation between IAP(ves) and IAP(rect) was poor and not significant in each position (p >= 0.25, R-2 < 0.6, Lin's CCC < 0.8, bias - 8.1 mmHg and precision of 5.6 mmHg with large limits of agreement between - 19 to 2.9 mmHg, high percentage error 67.3%, and low concordance 86.2%). Repeatability of IAP(rect) was not reliable (R = 0.539, p = 0.315). For both techniques, measurements with the external abdominal pressure belt were significantly higher compared to those without (p < 0.03). IAP(rect) has important shortcomings making IAP estimation using a rectal catheter unfeasible because the numbers cannot be trusted nor validated. This work is part of a PhD-thesis, which is supported by the Limburg Clinical Research Program (LCRP) UHasselt-ZOL-Jessa, supported by the foundation Limburg Sterk Merk, Hasselt University, Ziekenhuis Oost-Limburg and Jessa Hospital. The authors want to thank Robert Wise, Sharona Vonck, Inneke de Laet, Karen Schoonheydt, Hilde Dits, Salar Tayebi, and Wojciech Dabrowski for their help and advice performing the study and editing and revising this manuscript. Manu Malbrain is professor at the Medical University of Lublin and member of the Executive Committee of the Abdominal Compartment Society, formerly known as the World Society of Abdominal Compartment Syndrome (https:// www.wsacs.org/). He is co-founder, past-president and current treasurer of WSACS. He is co-founder of the International Fluid Academy (IFA). The mission statement of the IFA is to foster education, promote research on fuid management and hemodynamic monitoring, and thereby improve survival of critically ill by bringing together physicians, nurses, and others from throughout the world and from a variety of clinical disciplines. The IFA is integrated within the not-forproft charitable organization iMERiT, International Medical Education and Research Initiative, under Belgian law. The content of the IFA website (http://www.fuidacademy.org) is based on the philosophy of FOAM (Free Open Access Medical education—#FOAMed).

PurposeThis study aimed to investigate Doppler characteristics of maternal internal jugular veins in uncomplicated pregnancies vs. those affected by hypertensive disorders.Materials and methodsVenous pulse transit time and venous impedance index were measured at three different locations (right proximal, right distal, left proximal) of internal jugular veins according to a standardised combined Doppler-Electrocardiogram protocol in five different groups of pregnant women: uncomplicated pregnancy, early-onset preeclampsia, late-onset preeclampsia, gestational hypertension, and normotensive pregnancies with a small for gestational age foetus. Values of both parameters of the latter four groups were plotted against the reference range of uncomplicated pregnancies at corresponding gestation. Linear mixed models with random intercept were used to investigate gestational changes in venous pulse transit time and venous impedance index at the three internal jugular vein locations within and between the different groups.ResultsA total of 127 women were included: 41 had uncomplicated pregnancies, 13 had early-onset preeclampsia, 25 had late-onset preeclampsia, 22 had gestational hypertension, and 26 had normotensive pregnancies with a small for gestational age foetus. Venous pulse transit time values were lower than uncomplicated pregnancy (p ≤ 0.001) at all three locations in the third trimester of early-onset preeclampsia.ConclusionContrary to late-onset preeclampsia and gestational hypertension, early-onset preeclampsia is characterised by a lower venous pulse transit time at internal jugular veins compared to uncomplicated pregnancy, suggesting increased venous vascular tone.

This narrative review summarizes current evidence on the association between maternal low volume circulation and poor fetal growth. Though much work has been devoted to the study of cardiac output and peripheral vascular resistance, a low intravascular volume may explain why high vascular resistance causes hypertension in women with preeclampsia (PE) that is associated with fetal growth restriction (FGR) and, at the same time, presents with normotension in FGR itself. Normotensive women with small for gestational age babies show normal gestational blood volume expansion superimposed upon a constitutionally low intravascular volume. Early onset preeclampsia (EPE; occurring before 32 weeks) is commonly associated with FGR, and poor plasma volume expandability may already be present before conception, thus preceding gestational volume expansion. Experimentally induced low plasma volume in rodents predisposes to poor fetal growth and interventions that enhance plasma volume expansion in FGR have shown beneficial effects on intrauterine fetal condition, prolongation of gestation and birth weight. This review makes the case for elevating the maternal intravascular volume with physical exercise with or without Nitric Oxide Donors in FGR and EPE, and evaluating its role as a potential target for prevention and/or management of these conditions. Publication fee will be paid by the research fund of WG (see further).

BACKGROUND AND AIM: Falling during pregnancy can seriously harm mother and child, and should thus be avoided. However, 1/4 women report falling during pregnancy. Pregnant women show a decreased postural balance (i.e., greater sway variability and velocity), particularly during the second part of pregnancy. Unfortunately, the underlying mechanisms are poorly understood. Postural balance depends greatly on proprioceptive inputs from e.g., ankle and lumbar muscles. Depending on the postural condition, the brain will adjust the weight assigned to these inputs. For example during standing on unstable support surfaces, healthy individuals up-weight lumbar proprioception and down-weight ankle proprioception. So far, it remains unclear whether the weighting of ankle and lumbar proprioception during postural control differs in pregnant compared to non-pregnant women. METHODS: We recruited 12 pregnant, multiparous women in the third trimester, and 20 non-pregnant women. Exclusion criteria were a history of surgery/major trauma to spine, pelvis or lower limbs; specific balance or neurological disorders; and acute ankle problems. All women stood on a force plate (AMTI), with the heels 20 cm apart and vision occluded. After 20 s, muscle vibration (60 Hz, 15 s) was applied to the ankle or lumbar muscles. A stable and unstable support surface was used. Center-of-pressure (COP) displacements during vibration, and the Relative Proprioceptive Weighting (RPW) ratio, a measure of ankle vs. lumbar proprioceptive dominance, were calculated. Group differences in age, and pre-pregnancy BMI were determined with Mann-Whitney U tests, differences in COP displacement during vibration, and RPW ratio with mixed-design ANOVAs with "Surface" as the within-subjects factor, and "Pregnant" as the between-subjects factor. RESULTS: Pregnant women were significantly older (31 (30-34) vs. 28 (27-30) years, p= 0.004), and reported lumbopelvic pain more often (7/12 vs. 1/20, p= 0.002) than the non-pregnant controls. Pre-pregnancy BMI did not differ between groups (23.3 (21.4-27.2) vs. 22.4 (21.1-23.8), p= 0.219). For COP displacement during lumbar muscle vibration, a significant interaction effect of "Pregnant x Surface" was found (F= 8.157, p= 0.009). Post-hoc tests showed a significantly larger COP displacement during lumbar muscle vibration on the unstable compared to the stable support surface in the non-pregnant women (p< 0.001), but not in the pregnant group (p= 0.065). CONCLUSIONS: While non-pregnant women adequately up-weighted lumbar proprioception when switching from the stable to the unstable support surface, pregnant women did not show this increase in reliance on lumbar proprioception when needed. Future research must determine whether this decreased ability for proprioceptive re-weighting in pregnant women is already present in early pregnancy or even before conception, and whether it correlates to the presence of lumbopelvic pain and an increased risk of falling. ACKNOWLEDGEMENTS AND FUNDING: The authors wish to thank all participants. Nina Goossens is a beneficiary of an AXA Research Fund Postdoctoral Grant.