Ambulatory measurement of the timing of Korotkoff sounds in a group of normal subjects: influence of age and height.

Ambulatory measurement of timing of Korotkoff sounds (QKD interval) gives an estimate of arterial distensibility derived from the velocity of the pulse wave over a vascular territory that includes the ascending aorta. The main advantages of the method are that it is entirely automatic, non-operator-dependent, and highly reproducible, and produces a measure independent of instantaneous blood pressure. This study of a group of 180 normal subjects aged between 10 and 78 years was designed to produce references values and to study the influence of height. The results confirmed the reduction with age of arterial distensibility in the whole population. However before the age of 30, QKD100-60 was positively correlated with height according to the relationship QKD100-60 = 0.73 height (cm) + 91, but not with age. This equation enables calculation of the theoretical value of QKD100-60 as a function of height for any patient to which the observed value can be expressed as a percentage. This effectively eliminates the influence of height, which reflects the length of the arterial segment under investigation.