Effect of timing of blood pressure measurement in the assessment of arterial stiffness: The SMART study

In the assessment of arterial stiffness, pulse pressure is measured. Presently, there is no consensus on how pulse pressure should be measured. Distensibility of the left and right common carotid arteries was measured noninvasively in 224 patients participating in the Second Manifestations of ARTerial disease (SMART) study. Blood pressure was recorded every 4 min, using a semiautomatic oscillometric device. Distensibility coefficients (DC) were calculated with pulse pressure obtained as an average of (A) all measurements during the session; (B) the second, third, and fourth measurement; (C) measurements before and after distensibility assessment; and (D) three measurements nearest to distensibility assessment. Associations of: cardiovascular risk factors with the four calculated DCs were evaluated with linear regression analysis. DC estimates were slightly more precise with methods A and B than with C or D, The magnitude of the associations showed a slight trend to higher precision for methods A and B, Pulse pressures obtained as an average of all or the second, third, and fourth blood pressure measurements during an arterial stiffness measurement session yield slightly more precise estimates of DC. However, the differences between the methods are small; therefore, we suggest that pragmatic arguments dominate the choice between the methods. (C) 1998 World Federation for Ultrasound in Medicine & Biology.