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Purpose The dynamic response of pressure monitoring circuits must be evaluated to obtain true invasive blood pressure values. Since Gardner's recommendations in 1981, the natural frequency and the damping coefficient have become standard parameters for anesthesiologists. In 2006, we published a new dynamic response evaluation method (step response analysis) that can plot frequency spectrum curves instantly in clinical situations. We also described the possibility of the defect of the standard parameters. However, the natural frequency and the damping coefficient are considered the gold standard and are even included in a major anesthesiology textbook. Therefore, we attempted to clarify the issues of these parameters with easy-to-understand pressure waves and basic numerical formulae. Methods A blood pressure wave calibrator, a single two-channel pressure amplifier, and personal computer were used to analyze blood pressure monitoring circuits. All data collection and analytical processes were performed using our step response analysis program. Results We compared two different circuits with almost the same natural frequency and damping coefficients. However, their amplitude spectrum curves and input/output pressure values were significantly different. Conclusions The natural frequency and the damping coefficient are inadequate for the dynamic response evaluation. These parameters are primarily obtained from the phase spectrum curve and not from the amplitude spectrum curve. We strongly recommend an evaluation using the amplitude spectrum curve with our step response analysis method. It is crucial to maintain an amplitude gain of 1 (input amplitude = output amplitude) in the pressure wave frequency range of 0-20 Hz., Author(s): Hiroaki Watanabe [sup.1], Shin-ichi Yagi [sup.2] Author Affiliations: (1) grid.263171.0, 0000 0001 0691 0855, Department of Anesthesiology, School of Medicine, Sapporo Medical University, , South-1, West-16, Chuo-ku, 060-8543, Sapporo, [...]

The static mechanical properties of major branches of the human arteries (common carotid artery, abdominal aorta, femoral artery, and brachial artery) were studied in 39 subjects, aged 6-81 years, using an ultrasonic phase locked echo tracking system that allows continuous transcutaneous measurement of the diameter of the artery. The stiffness indices were calculated from the relation between systemic blood pressure and arterial diameter. With advancing age there was a significant increase in the diameter of all arteries associated with a reduction in percentage change in diameter. The stiffness index increased with age in all arteries; however, in the brachial and femoral arteries there was considerable variation in the individual values for a given age. The age associated increase in stiffness was statistically significant only in the common carotid artery and the abdominal aorta. Although the mechanical properties of the peripheral arteries were significantly influenced by the measuring environment, the calculated stiffness indices were less vulnerable to these stimuli in the central arteries. These results indicate that the stiffness indices of the peripheral muscular arteries are modified appreciably by vasoactive stimuli and that the mechanical properties of the deeper elastic arteries provide sufficiently reliable information about changes caused by aging and arteriosclerosis. The new ultrasonic method used appears to be suitable for this analysis. [ABSTRACT FROM PUBLISHER]

Background: To grasp the asthma patients' control level, an asthma control test (ACT), an easy questionnaire, is getting to be used as the alternative method of asthma diary recording. ACT is based on the patient's 4-week memory and the accuracy is not confirmed thoroughly, Methods: Two hundred and eighty three visits of 88 asthmatics (male 29, female 59) were subjected. The accuracy of ACT to detect "truly good control" was analyzed by comparing with the asthma diary (symptoms and PEF were recorded)., Results: Sensitivities, specificities (chi square values) for extraction of truly good control were 0.88, 0.42 (23.7) by the threshold of ACT > or =23, 0.77, 0.51 (18.1) by ACT > or =24, and 0.54, 0.69 (12.9) by ACT=25, significantly (p<0.001, respectively). When PEF% predicted > or =80% was added as the second factor, the chi square values improved to 29.9 by ACT > or =23 and to 30.3 by ACT > or =24 significantly (p<0.001, respectively)., Conclusion: Addition of PEF measurement on visit on ACT may help understanding the asthmatic patient condition.