Continuous blood pressure measurement using the pulse transit time: Comparison to intra-arterial measurement

Figures & data

Table I. Characteristics of the subjects and correlation coefficients (CC) for systolic (Syst.) and diastolic (Diast.) blood pressure.

Subject no.	Gender	Age years)	Height (cm)	Body mass (kg)	BMI (kg/m^2)	CC Syst.	CC Diast.	No. of data pairs
1	M	23	191	72	24.1	0.959	0.945	9
2	M	21	180	72	22	0.934	0.685	9
3	F	25	187	70	22.9	0.620	0.666	9
4	M	27	177	87	28.4	0.912	0.810	9
5	F	37	161	87	24.9	0.926	–0.672	9
6	M	53	169	72	23.2	0.781	0.204	9
7	F	27	185	64	23.2	0.872	0.679	9
8	F	33	173	62	21.0	0.799	0.037	9
9	M	29	163	74	23.4	0.932	–0.125	9
10	F	26	183	50	19.8	0.937	0.367	9
11	M	23	183	83	25.6	0.984	0.852	9
12	M	22	163	70	22.6	0.966	0.012	8*, 9

*8 data pairs for systolic blood pressure.

M, male; F, female; BMI, body mass index.

Figure 1. Effect of dobutamine on (a) systolic blood pressure and (b) diastolic blood pressure measured intra-arterially (BP i.a., open boxes) and using the pulse transit time (BP PTT, grey boxes) presented as box-and-whisker plots: 5th, 25th, 50, 75th and 95th percentiles with outliers (dots). Doses 1–3 correspond to 5, 10 and 20 μg/kg body mass. *Significant difference compared to BP i.a.

Figure 2. (a) Scatterplot of systolic blood pressure measured i.a. (BPsyst i.a.) versus systolic blood pressure calculated from the pulse transit time (BPsyst PTT) for all subjects and measurements. (b) Bland—Altman plot of the systolic blood pressure (BP) data of all subjects and measurements (n ± 107). The limits of agreement (± 1.96 SD) were ± 18.9 mmHg; the mean difference between the methods was 0.78 mmHg.

Figure 3. (a) Scatterplot of diastolic blood pressure measured intra-arterially (BPdiast i.a.) versus diastolic blood pressure calculated from the pulse transit time (BPdiast PTT) for all subjects and measurements. (b) Bland—Altman plot of the diastolic blood pressure (BP) data of all subjects and measurements (n = 108). The limits of agreement (± 1.96 SD) were ± 18.05 mmHg; the mean difference between the methods was 4.78 mmHg.