Noninvasive Blood Pressure Monitor Designed for Patients With Heart Failure Supported with Continuous-Flow Left Ventricular Assist Devices

Abstract

The gold standard for noninvasive blood pressure (BP) measurement, the Doppler technique, does not provide systolic blood pressure (SBP) and diastolic blood pressure (DBP) and may limit therapy outcomes. To improve patient care, we tested specifically designed experimental BP (ExpBP) monitor and the Doppler technique by comparing noninvasive measures to the intraarterial (I-A) BP in 31 patients with end-stage heart failure (4 females) 2.6 ± 3.4 days post-LVAD implantation (20 HeartMate II and 11 HeartWare). Bland-Altman plots revealed that the ExpBP monitor overestimated mean arterial pressure (MAP) by 1.2 (4.8) mm Hg (mean difference [standard deviation]), whereas the Doppler by 6.7 (5.8) mm Hg. The ExpBP SBP was overestimated by 0.8 (6.1) mm Hg and DBP by 1.9 (5.3) mm Hg compared with the respective I-A pressures. Both techniques achieved similar measurement reliability. In the measurement "success rate" expressed as a frequency (percent) of readable BP values per measurement attempts, Doppler accomplished 100% vs. 97%, 97%, and 94% of successful detections of MAP, SBP, and DBP provided by the ExpBP monitor. The ExpBP monitor demonstrated higher accuracy in the MAP assessment than the Doppler in addition to providing SBP and DBP in majority of subjects. Improved BP control may help to mitigate related neurologic adverse event rates.

Radial Artery Tonometry to Monitor Blood Pressure and Hemodynamics in Ambulatory Left Ventricular Assist Device Patients in Comparison With Doppler Ultrasound and Transthoracic Echocardiography: A Pilot Study

“…), BP is required to be assessed in 30 subjects from the particular studied population and evaluated against a reference method. The difference in BP values obtained by a tested method and a reference method must be ≤15 mm Hg in at least 95% of measurements, ≤10 mm Hg in at least 85%, and at least ≤5 mm Hg in at least 60% of measurements to achieve the highest degree of accuracy (grade A) (23,24). In our study, the BPPA achieved 96.8, 87.5, and 53% for SBP in categories <15, <10, and <5 mm Hg, respectively.…”

“…Sajgalik et al developed an experimental, noninvasive, brachial cuff blood pressure (ExpBP) with a specific algorithm, which is designed for CF‐LVAD patients, with very promising results. They demonstrated low mean absolute differences between ExpBP monitor MAP versus A‐line MAP and Doppler BP versus A‐line MAP, 3.9 ± 1.1 and 7.5 ± 1.0 mm Hg, respectively.…”

Non-invasive assessment of arterial pulsatility in patients with continuous-flow left ventricular assist devices

“…There are, of course, several methods available to assess and monitor arterial pulsatility in LVAD patients. For example, arterial pulse pressure may be obtained via the 'oscillometric' method 22 or from a finger photoplethysmograph. 16 Yet, although the former method is easily implement using an automated cuff inflator, the latter requires expensive hardware to implement the 'volume-clamp' method to reconstruct the arterial pulse wave.…”

Impact and Measurement of Blood Pressure During Continuous Flow Left Ventricular Assist Device Support: The Pressure Is On!

“…Because of this reduction in PP, the standard method of noninvasive BP measurement by deflating a sphygmomanometer reliant on transduction of acoustics or vibratory oscillations can only give measurements in at best 60% of the patients, 16 notwithstanding accuracy. To overcome these limitations, several noninvasive methods of BP measurement have been proposed (Figure 1) [17][18][19][20] At this time, Doppler ultrasound is the most commonly used method for BP measurement during CF LVAD support. However, this Doppler technique, which yields the highest pressure that arterial flow is restored during cuff deflation, has limited ability to distinguish between SBP and MAP.…”

“…17 Finger cuff methods such as the Nexfin device have provided accurate BP measurements at higher CF LVAD speeds corresponding to low PP, but these devices have not been validated in a large number of patients, require specialized equipment, and may not yield measurements during vasoconstriction apparent by cold extremities. 19 To surmount limitations of noninvasive BP measurement in CF LVAD patients, Sajgalik et al 20 assessed the validity, repeatability, and measurement success rate of a novel brachial cuff pressure experimental BP (ExpBP) monitor. This ExpBP device used standard oscillometric mechanics, with customized hardware and software for low pulsatility and an ability to measure pulsations during cuff deflation at 2 mm Hg/second.…”