Limited accuracy of the hyperbaric index, ambulatory blood pressure and sphygmomanometry measurements in predicting gestational hypertension and preeclampsia.

Objective: The aim of this study was to validate the hyperbaric index (HBI) for first trimester prediction of preeclampsia and gestational hypertension.

Methods: Participants were low-risk and high-risk nulliparous women and high-risk multiparous women, and were recruited between April 2004 and June 2006. At a gestational age of 9 weeks (range 8-11 weeks), blood pressure (BP) was measured first by sphygmomanometry and thereafter by ambulatory BP measurement (ABPM) for 48 h.

Validation of the Bayesian Alcoholism Test compared to single biomarkers in detecting harmful drinking.

Aims: Conventional tests for alcohol dependence often fail to detect hazardous and harmful alcohol use (HHAU) accurately. We previously validated the Bayesian Alcoholism Test (BAT) for the detection of HHAU among males. This uses 15 biochemical and clinical variables, including questionnaire data to calculate the probability of harmful (>80 g alcohol/day), hazardous (40-80 g/day) and 'moderate' (<40 g/day) drinking.

24-hr blood pressure in HDT-bed rest and short-lasting space flight.

In 2 ESA-cosmonauts we compared the 24-hr profiles in blood pressure (BP) and heart rate (HR) to those that we had observed in an earlier head-down tilted (HDT) bed rest study. In view of the lack of gravitational stress, an attenuated profile was expected, as in HDT. To obtain a full profile we measured automatic upper-arm cuff measurements in 2 cosmonauts, combined with PortapresTM recordings in one.

Time course analysis of baroreflex sensitivity during postural stress.

Postural stress requires immediate autonomic nervous action to maintain blood pressure. We determined time-domain cardiac baroreflex sensitivity (BRS) and time delay (tau) between systolic blood pressure and interbeat interval variations during stepwise changes in the angle of vertical body axis (alpha). The assumption was that with increasing postural stress, BRS becomes attenuated, accompanied by a shift in tau toward higher values.

Tilt table design for rapid and sinusoidal posture change with minimal vestibular stimulation.

Introduction: Cardiovascular response to fast posture change can be used to model individual orthostatic response under normal circumstances and after spaceflight. We set out to construct a computer-controlled tilt table suitable for repeated sinusoidal tilt motion as well as fast, single head-up tilt (HUT). The movement profile of the table was designed to prevent muscle tensing and limit vestibular stimulation.

Hemodynamic effects of leg crossing and skeletal muscle tensing during free standing in patients with vasovagal syncope.

Physical maneuvers can be applied to abort or delay an impending vasovagal faint. These countermaneuvers would be more beneficial if applied as a preventive measure. We hypothesized that, in patients with recurrent vasovagal syncope, leg crossing produces a rise in cardiac output (CO) and thereby in blood pressure (BP) with an additional rise in BP by muscle tensing.

Sublingual nitroglycerin used in routine tilt testing provokes a cardiac output-mediated vasovagal response.

Objectives: We set out to determine the effect of sublingual nitroglycerin (NTG), as used during routine tilt testing in patients with unexplained syncope, on hemodynamic characteristics and baroreflex control of heart rate (HR) and systemic vascular resistance (SVR).

Background: Nitroglycerin is used in tilt testing to elicit a vasovagal response. It is known to induce venous dilation and enhance pooling.

Time-domain cross-correlation baroreflex sensitivity: performance on the EUROBAVAR data set.

Objective: To test a new method (cross-correlation baroreflex sensitivity, xBRS) for the computation of time-domain baroreflex sensitivity on spontaneous blood pressure and heart interval variability using the EUROBAVAR data set.

Methods: We applied xBRS to the 42 records in the EUROBAVAR data set, obtained from 21 patients in the lying and standing positions. One patient had a recent heart transplant and one was diabetic with evident cardiac autonomic neuropathy.

Tidal volume, cardiac output and functional residual capacity determine end-tidal CO2 transient during standing up in humans.

In man assuming the upright position, end-tidal P(CO(2)) (P(ETCO(2))) decreases. With the rising interest in cerebral autoregulation during posture change, which is known to be affected by P(ETCO(2)), we sought to determine the factors leading to hypocapnia during standing up from the supine position. To study the contribution of an increase in tidal volume (V(T)) and breathing frequency, a decrease in stroke volume (SV), a ventilation-perfusion (V/Q) gradient and an increase in functional residual capacity (FRC) to hypocapnia in the standing position, we developed a mathematical model of the lung to follow breath-to-breath variations in P(ETCO(2)).