cuffles blood pressure measurement regression equation

fonda99

Has anyone tried to apply the following regression eqation appeared in the paper "Continuous measurement of systolic blood pressure using the PTT and other parameters" (Proceedings of the 2005 IEEE Engineering in Medicine and Biology 27th Annual Conference Shanghai, China, September 1-4, 2005):

SystolicBP = 85.862 -119,27 PTT +0.259 weight + 0.439 arm length

(Blood pressure in mmHg, PTT is Pulse Transit Time[ms], weight[Kg], arm length[cm])

Nice linear relationship but I get absurd values for BP.
Any help is greatly appreciated.

Moonbear

I had never heard of it before, and had to look up what pulse transit time is. Other reputable sources refer to it as directly proportional to blood pressure, but if that's the case, then factoring in weight doesn't make sense. I also suspect it ought to then not be arm length, but the distance between the two pulse points being used to measure PTT. For example, if you're measuring transit time between brachial and radial pulses, it might matter the length of the forearm, not the arm. It seems to me that it would be more difficult to accurately measure PTT than BP. Did the article offer any reason to choose one method over the other?

fonda99

Oops, sorry for lack of infos.
Pulse transit time is the time interval between the R peak of electrocardiogram (ECG) and the systolic peak of the signal recorded through the photoplethysmograph at one finger (the signal is created by the sensor which detects the reflectance variations of an illuminating infrared beam in the finger). Larger the pressure, smaller the pulse transit time (PTT), so it is inversely related to blood pressure. The article doesn't compare the method with other methods; its aim is to introduce a method to avoid blood pressure calibration and cuff usage, to measure systolic pressure of any subject in a non intrusive way.