Abstract-Brachial artery cuff blood pressures are but approximations of central aortic pressures. The actual pressures against which the left ventricle must pump would be useful clinical information if obtained noninvasively. Our aim was to determine the clinical utility of aortic pulses and pressures calculated from noninvasively obtained radial-artery pulses. Radial-arterial pulses were recorded by applanation and calibrated with arm/cuff oscillometric pressures. Aortic pulses and pressures were calculated from the radial pulses by Fourier analysis and transfer functions. These calculated aortic pulses were compared with directly recorded aortic pulses by a transducer-tip catheter in a series of 50 patients undergoing cardiac catheterization. The correlation coefficient (r) of the measured versus the calculated aortic systolic blood pressure was ϩ0.89, but the scatter was large (standard deviation of the differencesϭϮ11.3 mm Hg). The pulse pressure correlations were less good (rϭϩ0.79) and also had a large scatter (Ϯ13.6 mm Hg). The average calculated pulse pressure was 11.5 mm Hg lower than the measured value because the cuff diastolic blood pressures, used to calibrate the radial pulses, were systematically higher than those in the aorta (8.9 mm Hg). Multivariable analysis incorporating height, age, heart rate, and ejection fraction as additional, independent variables eliminated mean differences between the new "predicted" and measured pressures, significantly improved correlation coefficients, and reduced the scatter. However, the improvements were small. The inaccuracy of the oscillometric cuff method for measuring arm blood pressure appears to be the limiting factor in the prediction of clinically useful, noninvasive aortic pressures. Key Words: aorta Ⅲ arterial pressure Ⅲ Fourier analysis Ⅲ blood pressure determination T he cuff technique for the measurement of brachial-artery (BA) pressure has been of inestimable benefit in the diagnosis and treatment of multiple diseases. It is well known, however, that BA pressure is not the same as and is often an inaccurate estimate of central aortic pressure. The difference between the 2 pressures is difficult to predict because it is influenced by many factors, such as body height, age, heart rate, stroke volume, ejection time, and the distensibility of the conduit arterial tree. An accurate, noninvasive method to measure aortic pressures would be an important clinical advance. It would permit better estimates of cardiac work, better diagnoses of hypertension, and the response to antihypertensive treatment; improve the correction of hemodynamic abnormalities in hypotensive states; and offer better assessments of the pressor responses to exercise stress, during which arm pressures are known to be falsely elevated. 1 Aortic pressures can now only be measured accurately by invasive catheterization, a method unsuitable for widespread clinical use. O'Rourke and colleagues 2-5 have proposed a solution involving transformation of the applanated and calibrated radial-art...

Objective To correlate epidemiologic factors with urogenital infections associated with preterm birth. Methods Pregnant women were sequentially included from four Wisconsin cohorts: large urban, midsize urban, small city, and rural city. Demographic, clinical, and current pregnancy data were collected. Cervical and urine specimens were analyzed by microscopy, culture, and polymerase chain reaction for potential pathogens. Results Six hundred seventy-six women were evaluated. Fifty-four (8.0%) had preterm birth: 12.1% (19/157) large urban, 8.8% (15/170) midsize urban, 9.4% (16/171) small city, and 2.3% (4/178) rural city. Associated host factors and infections varied significantly among sites. Urogenital infection rates, especially Mycoplasma hominis and Ureaplasma parvum, were highest at the large urban site. Large urban site, minority ethnicity, multiple infections, and certain historical factors were associated with preterm birth by univariable analysis. By multivariable analysis, preterm birth was associated with prior preterm birth (adjusted odds ratio [aOR] 2.76, 95% confidence interval [CI] 1.27–6.02) and urinary tract infection (aOR 2.62, 95% CI 1.32–519), and negatively associated with provider-assessed good health (aOR 0.42, 95% CI 0.23–0.76) and group B streptococcal infection treatment (surrogate for healthcare utilization) (aOR 0.38, 95% CI 0.15–.99). Risk and protective factors were similar for women with birth at < 35 weeks, and additionally associated with M hominis (aOR 3.6, 95% CI 1.4–9.7). Conclusion These measured differences between sites are consistent with observations that link epidemiologic factors, both environmental and genetic, with minimally pathogenic vaginal bacteria, inducing preterm birth, especially at less than 35 weeks of gestation.