Adult guide-lines are not applicable to measure PWV path length in paediatrics
E. Kis, O. Cseprekal, A.A. Degi, P. Salvi, A. Benethos, A.J. Szabo, G.S. Reusz
2013
Artery Research
The method used for pulse transit time (PTT) estimation, affects critically the accuracy of pulse wave velocity (PWV) measurements. The existing methods for PTT estimation yield often substantially different PWV values. Since there is no analytical way to determine PTT in vivo, these methods cannot be validated except by using in silico or in vitro models of known PWV and PTT. We aimed to validate and compare the most commonly used "footto-foot" methods: "diastole-minimum", "tangential",
more »
... m 1st derivative" and "maximum 2nd derivative". Also, we propose a new "diastolepatching" algorithm aiming to increase the accuracy and precision in PWV measurement. Methods: We simulated 2000 cases under a range of different hemodynamic conditions using a validated, distributed 1-D arterial model. The new algorithm "matches" a specific region of the pressure-wave foot between the proximal (i.e. carotid) and distal (i.e. femoral) waveforms. Intraclass correlation coefficient (ICC), mean difference (bias) and standard deviation of differences (SDD) were used to assess accuracy and precision. Results: The " diastole-minimum" and the " diastole-patching" methods showed an excellent agreement compared to the "real" PWV values of the model, as indicated by high values of ICC(>0.86). The "diastole patching" method resulted in low bias (0.26m/s). In contrast, PWV estimated by 1st or 2nd derivatives and the "tangential" method presented a low to moderate agreement and poor accuracy (ICC<0.79, bias>0.9 m/s). The "diastole-patching" method yielded PWV measurements with the highest agreement, accuracy, precision and the lowest variability and its validity remains to be further examined in vivo. Background: Wave intensity analysis (WIA) is a mathematical tool used to study wave reflections in the arteries. Reflections are believed to contribute to BP augmentation and are also independent predictors of cardiovascular risk. Until now, the use of this technique has been largely confined to the aorta and carotid arteries. Methods: 8 healthy subjects (age 30 AE 7.1) underwent wrist occlusion using a cuff inflated to >50mmHg suprasystolic pressure for 5min and hand warming at 55 C for 12min. Brachial artery diameter and blood flow velocity were measured using wall tracking and doppler ultrasound with an ALOKA SSD-5550 equipped with a 7.5 MHz probe. Wave intensity was calculated and reflections were quantified as the energy of the reflected wave/energy incident wave (WRI, %). Central aortic pressure following hand warming was also estimated using applanation tonometry (Sphygmocor) in separate studies.
doi:10.1016/j.artres.2013.10.194
fatcat:eppdsf67bvgyloypdgr24y547m