Is it feasible to measure intra-abdominal pressure using a balloon-tipped rectal catheter? Results of a validation study.

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 (IAPrect) may overcome these limitations, but requires validation. This validation study compares the IAPrect technique against gold standard intra-vesical IAP measurements (IAPves). IAPrect using an air-filled balloon catheter and IAPves using Foley Manometer Low Volume were measured simultaneously in sedated and ventilated patients. Measurements were performed twice in different positions (supine and HOB 45° elevated head of bed) and with an external abdominal pressure belt. Sixteen patients were included. Seven were not eligible for analysis due to unreliable IAPrect values. IAPrect was significantly higher than IAPves for all body positions (p < 0.01) and the correlation between IAPves and IAPrect was poor and not significant in each position (p ≥ 0.25, R2 < 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 IAPrect 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). IAPrect has important shortcomings making IAP estimation using a rectal catheter unfeasible because the numbers cannot be trusted nor validated.

Development of a biophysical screening model for gestational hypertensive diseases.

BACKGROUND: To investigate the possibility of using maternal biophysical parameters only in screening for the different types of gestational hypertensive diseases. METHODS: A total of 969 pregnant women were randomly screened in first and second trimester, of which 8 developed Early-onset Preeclampsia, 29 Late-onset Preeclampsia, 35 Gestational Hypertension and 897 women had a normal outcome. An observational maternal hemodynamics assessment was done via standardized electrocardiogram-Doppler ultrasonography, Impedance Cardiography and bio-impedance, acquiring functional information on heart, arteries, veins and body fluid. Preliminary prediction models were developed to test the screening potential for early preeclampsia, late preeclampsia and gestational hypertension using a Partial Least Square Discriminant Analysis. RESULTS: A combined model using maternal characteristics with cardiovascular parameters in first and second trimester offers high screening performance with Area Under the Curve of 99,9% for Early-onset Preeclampsia, 95,3% for Late-onset Preeclampsia and 94% for Gestational Hypertension. CONCLUSIONS: Using biophysical parameters as fundament for a new prediction model, without the need of biochemical parameters, seems feasible. However, validation in a large prospective study will reveal its true potential.

Type-specific orthostatic hemodynamic response of hypertensive diseases in pregnancy.

Posture changes may differ between types of hypertensive disease. The aim is to evaluate the orthostatic response of impedance cardiography (ICG) measurements in uncomplicated and hypertensive pregnancies. Measurements were performed in supine and standing position in 202 women: 41 uncomplicated pregnancies (UP), 59 gestational hypertension (GH), 35 early-onset (EPE, < 34 weeks) and 67 late-onset (LPE, ≥ 34 weeks) preeclampsia were assessed. Measurements were recorded of heart rate, blood pressure, aortic flow parameters, cardiac output, pre-ejection period and left ventricular ejection time. Overall, orthostatic shifts were different between all groups (P < 0.001). UP was different from the hypertensive complicated gestations in the orthostatic change of the aortic acceleration. In contrast to patients with preeclampsia, those with GH had an increased blood pressure and Heather index, and stable pre-ejection period after posture change. EPE differed from LPE by change in blood pressure and aortic flow parameters. In addition to static ICG-measurements, orthostatic shifts improved group characterization from 57.4% to 65.8%. The orthostatic response is altered in hypertensive pregnancies. ICG measurements in the upright as well as during an orthostatic test might have the potential to improve the discriminative yield between hypertensive diseases in pregnancy.

Maternal body fluid composition in uncomplicated pregnancies and preeclampsia: a bioelectrical impedance analysis.

OBJECTIVES: Body fluid composition changes during the course of pregnancy and there is evidence to suggest that these changes are different in uncomplicated pregnancies compared to hypertensive pregnancies. The aim of this study was to evaluate the changes in maternal body fluid composition during the course of an uncomplicated pregnancy and to assess differences in uncomplicated pregnancies versus hypertensive pregnancies by using a bio-impedance analysis technique. STUDY DESIGN: Body fluid composition of each patient was assessed using a multiple frequency bioelectrical impedance analyser. Measurements were performed in 276 uncomplicated pregnancies, 34 patients with gestational hypertension, 35 with late onset preeclampsia and 11 with early onset preeclampsia. Statistical analysis was performed at nominal level α=0.05. A longitudinal linear mixed model based analysis was performed for longitudinal evolutions, and ANOVA with a post-hoc Bonferroni was used to identify differences between groups. RESULTS: Measurements showed that total body water (TBW), intracellular (ICW) and extracellular water (ECW) and ECW/ICW significantly increase during the course of pregnancy. Late onset preeclampsia is associated with a higher TBW and ECW as compared to uncomplicated pregnancies, the ECW/ICW ratio is higher in preeclamptic patients compared to uncomplicated pregnancies and gestational hypertension, and ICW is not different between groups. CONCLUSION: Body fluid composition changes differently during the course of uncomplicated pregnancies versus hypertensive pregnancies.

Improving the reliability of venous Doppler flow measurements: relevance of combined ECG, training and repeated measures.

The nature of venous Doppler waves is highly variable. An additional electrocardiogram (ECG) improves the interpretation of venous Doppler wave characteristics and allows measurement of venous pulse transit time. The purpose of this study was to assess the reproducibility of ECG-guided repeated measurements of venous Doppler flow characteristics before and after sonographer training and the inter- and intra-observer variability. In four groups of 25 healthy women, venous Doppler flow measurements were performed at the level of the kidneys and liver according to a standardized protocol. Intra-observer Pearson correlation coefficients of the renal interlobar vein Doppler indices were ≥ 0.80 with the addition of the ECG, which are higher than the results of a former study. The inter-observer correlation between an experienced ultrasonographer and an inexperienced ultrasonographer improved from ≥ 0.71 to ≥ 0.91 after training. The correlation range of all parameters between two independent observers improved when values were based on repeated measures. The addition of an ECG to the Doppler image, training and repeated measurements are helpful in improving venous Doppler wave interpretation.

Is there a correlation between maternal venous hemodynamic dysfunction and proteinuria of preeclampsia?

OBJECTIVES: To evaluate in early and late preeclampsia a correlation of maternal venous Doppler flow characteristics with biochemical parameters in maternal serum and urine, or with gestational outcome. STUDY DESIGN: In this observational cross-sectional study, renal interlobar vein impedance index (RIVI) was measured according to a standardised protocol for combined electrocardiogram-Doppler ultrasonography in 86 women with uncomplicated pregnancy, 78 women with late onset preeclampsia (≥34w) and 67 with early onset preeclampsia (<34w). For each group, maternal age, pre-gestational BMI and parity were recorded together with birth weight and -percentile. For both early onset and late onset preeclampsia, maternal serum was analysed for thrombocyte count and concentrations of creatinine, ASAT, ALAT and uric acid and 24h urine collections were analysed for creatinine clearance and proteinuria (mg/24h). A non-parametric Mann-Whitney U-tests was performed for continuous data and a Fisher's exact tests for categorical data. Significant linear dependence between variables was identified using Pearson's correlation coefficient at nominal level a=0.05. RESULTS: Proteinuria was higher in early onset than in late onset preeclampsia (1756mg [838-6116mg] versus 877mg [416-1696mg], p<0.001), and this was also true for RIVI in both left (0.45 [0.40-0.55] versus 0.41 [0.35-0.45], p=0.001) and right kidney (0.45 [0.39-0.55] versus 0.38 [0.30-0.43], p<0.001). In our data set, there was a significant correlation between proteinuria and RIVI of left (correlation coefficient=0.172, p=0.036) and right kidney (correlation coefficient=0.218, p=0.009) in late onset but not early onset preeclampsia. CONCLUSION: Maternal RIVI may correlate with proteinuria of late onset preeclampsia.

Intra-abdominal pressure measurements in term pregnancy and postpartum: an observational study.

OBJECTIVE: To determine intra-abdominal pressure (IAP) and to evaluate the reproducibility of IAP-measurements using the Foley Manometer Low Volume (FMLV) in term uncomplicated pregnancies before and after caesarean section (CS), relative to two different reference points and to non-pregnant values. DESIGN: Observational cohort study. SETTING: Secondary level referral center for feto-maternal medicine. POPULATION: Term uncomplicated pregnant women as the case-group and non-pregnant patients undergoing a laparoscopic assisted vaginal hysterectomy (LAVH) as control group. METHODS: IAP was measured in 23 term pregnant patients, before and after CS and in 27 women immediately after and 1 day after LAVH. The midaxillary line was used as zero-reference (IAPMAL) in all patients and in 13 CS and 13 LAVH patients, the symphysis pubis (IAPSP) was evaluated as additional zero-reference. Intraobserver correlation (ICC) was calculated for each zero-reference. Paired student's t-tests were performed to compare IAP values and Pearson's correlation was used to assess correlations between IAP and gestational variables. MAIN OUTCOME MEASURES: ICC before and after surgery, IAP before and after CS, IAP after CS and LAVH. RESULTS: The ICC for IAPMAL before CS was lower than after (0.71 versus 0.87). Both mean IAPMAL and IAPSP were significantly higher before CS than after: 14.0±2.6 mmHg versus 9.8±3.0 mmHg (p<0.0001) and 8.2±2.5 mmHg versus 3.5±1.9 mmHg (p = 0.010), respectively. After CS, IAP was not different from values measured in the LAVH-group. CONCLUSION: IAP-measurements using FMLV is reproducible in pregnant women. Before CS, IAP is increased in the range of intra-abdominal hypertension for non-pregnant individuals. IAP significantly decreases to normal values after delivery.