Why magnesium sulfate 'coverage' only is not enough to reduce eclampsia: Lessons learned in a middle-income country.

OBJECTIVES: Determine the eclampsia prevalence and factors associated with eclampsia and recurrent seizures in Suriname and evaluate quality-of-care indicator 'magnesium sulfate (MgSO4) coverage'. STUDY DESIGN: A two-year prospective nationwide cohort study was conducted in Suriname and included women with eclampsia at home or in a healthcare facility. MAIN OUTCOME MEASURES: We calculated the prevalence by the number of live births obtained from vital registration. Risk factor denominator data concerned hospital births. Descriptive statistics and multivariate regression analysis were performed. RESULTS: Seventy-two women with eclampsia (37/10.000 live births) were identified, including two maternal deaths (case-fatality 2.8%). Nulliparity, African-descent and adolescence were associated with eclampsia. Adolescents with eclampsia had significantly lower BPs (150/100 mmHg) than adult women (168/105 mmHg). The first seizure occurred antepartum in 54% (n = 39/72), intrapartum in 19% (n = 14/72) and postpartum in 26% (n = 19/72). Recurrent seizures were observed in 60% (n = 43/72). MgSO4 was administered to 99% (n = 69/70) of women; however 26% received no loading dosage and, in 22% of cases MgSO4 duration was <24 h, i.e. guideline adherence existed in only 43%. MgSO4 was ceased during CS in all women (n = 40). Stable BP was achieved before CS in 46%. The median seizure-to-delivery interval was 27 h, and ranged from four to 36 h. CONCLUSION: Solely 'MgSO4 coverage' is not a reliable quality-of-care indicator, as it conceals inadequate MgSO4 dosage and timing, discontinuation during CS, stabilization before delivery, and seizure-to-delivery interval. These other quality-of-care indicators need attention from the international community in order to reduce the prevalence of eclampsia.

Electron density characterization by use of a broadband x-ray-compatible wave-front sensor.

The use of a Hartmann wave-front sensor to accurately measure the line-integrated electron density gradients formed in laser-produced and z-pinch plasma experiments is examined. This wave-front sensor may be used with a soft-x-ray laser as well as with incoherent line emission at multikilovolt x-ray energies. This diagnostic is significantly easier to use than interferometery and moiré deflectometry, both of which have been demonstrated with soft-x-ray lasers. This scheme is experimentally demonstrated in the visible region by use of a Shack-Hartmann wave-front sensor and a liquid-crystal spatial light modulator to simulate a phase profile that could occur when an x-ray probe passes through a plasma. The merits of using a Hartmann sensor include a wide dynamic range, broadband or low-coherence-length light capability, high x-ray efficiency, two-dimensional gradient determination, multiplexing capability, and experimental simplicity. Hartmann sensors could also be utilized for wavelength testing of extreme-ultraviolet lithography components and x-ray phase imaging of biological specimens.

Performance of a phase-conjugate engine implementing a finite-bit phase correction.

The achievable Strehl ratio when a finite-bit correction to an aberrated wave front is implemented is examined. The phase-conjugate engine used to measure the aberrated wave front consists of a quadrature interferometric wave-front sensor, a liquid-crystal spatial light modulator, and computer hardware-software to calculate and apply the correction. A finite-bit approximation to the conjugate phase is calculated and applied to the spatial light modulator to remove the aberrations from the optical beam. The experimentally determined Strehl ratio of the corrected beam is compared with analytical expressions for the expected Strehl ratio and shown to be in good agreement with those predictions.

High-speed horizontal-path atmospheric turbulence correction with a large-actuator-number microelectromechanical system spatial light modulator in an interferometric phase-conjugation engine.

Results of atmospheric propagation for a high-speed, large-actuator-number adaptive optics system are presented. The system uses a microelectromechanical system- (MEMS-) based spatial light modulator correction device with 1024 actuators. Tests over a 1.35-km path achieved correction speeds in excess of 800 Hz and Strehl ratios close to 0.5. The wave-front sensor was based on a quadrature interferometer that directly measures phase. This technique does not require global wave-front reconstruction, making it relatively insensitive to scintillation and phase residues. The results demonstrate the potential of large-actuator-number MEMS-based spatial light modulators to replace conventional deformable mirrors.