Validation of beat by beat pulsed Doppler measurements of ascending aortic blood velocity in man

Innes, J A; Mills, Christopher; Noble, M. I. M.; Murphy, Kevin; Pugh, S.; Shore, Angela C.; Guz, A.

doi:10.1093/cvr/21.1.72

Cited by 40 publications

(31 citation statements)

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“…Ultrasound data were measured by an experienced cardiologist following best-practice guidelines. On the other hand, literature sources state that both techniques are equivalent 23,24 ; so it is unclear whether the method used to acquire the flow does play a role in our findings.…”

Section: Kips Et Al Wave Reflection and Pulse Transit Time Assessmentmentioning

confidence: 81%

Evaluation of Noninvasive Methods to Assess Wave Reflection and Pulse Transit Time From the Pressure Waveform Alone

et al. 2009

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Abstract-Accurate quantification of pressure wave reflection requires separation of pressure in forward and backward components to calculate the reflection magnitude as the ratio of the amplitudes backward and forward pressure. To do so, measurement of aortic flow in addition to the pressure wave is mandatory, a limitation that can be overcome by replacing the unknown flow wave by an (uncalibrated) triangular estimate. Another extended application of this principle is the derivation of aortic pulse transit time from a single pulse recording. We verified these approximation techniques for reflection magnitude and transit time using carotid pressure and aortic flow waveforms measured noninvasively in the Asklepios Study (Ͼ2500 participants; 35 to 55 years of age). A triangular flow approximation using timing information from the measured aortic flow waveform yielded moderate agreement between reference and estimated reflection magnitude (R 2 ϭ0.55). Approximating the flow by a more physiological waveform significantly improved these results (R 2 ϭ0.74). Aortic transit time was assessed using pressure and measured or approximated flow waveforms, and results were compared with carotid-femoral transit times measured by Doppler ultrasound. Agreement between estimated and reference transit times was moderate (R 2 Ͻ0.29). Both for reflection magnitude and transit time, agreement between reference and approximated values further decreased when the approximated flow waveform was obtained using timing information from the pressure waveform. We conclude that, in our Asklepios population, results from pressure-based approximative methods to derive reflection magnitude or aortic pulse transit time differ substantially from the values obtained when using both measured pressure and flow information. Key Words: hypertension Ⅲ blood pressure measurement/monitoring Ⅲ hemodynamics Ⅲ arterial stiffness Ⅲ wave reflection Ⅲ pulse wave velocity T he pressure pulse can be considered as the composite of a forward pressure wave, traveling from the heart to the periphery, and of a reflected pressure wave, traveling backward toward the heart. Early return of this reflected wave boosts (central) systolic blood pressure, increasing the load on the heart and boosting the amplitude of the pressure pulse, factors that have been shown to increase cardiovascular risk. [1][2][3][4] Therefore, analysis of pulse wave velocity and pressure wave reflection have been points of clinical interest for many years now.Several methods to quantify wave reflection emerged, 5 the most widespread probably being the augmentation index (AIx). 6,7 AIx is a parameter based on analysis of the pressure waveform and expresses the ratio of augmented pressure (attributed to wave reflection) to pulse pressure. However, because several factors influence its value, 8 -12 AIx might not be the most appropriate parameter for an accurate quantification of the magnitude of wave reflection. 13 More accurate methods to assess wave reflection are based on wave separation analysis....

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Section: Kips Et Al Wave Reflection and Pulse Transit Time Assessmentmentioning

confidence: 81%

Evaluation of Noninvasive Methods to Assess Wave Reflection and Pulse Transit Time From the Pressure Waveform Alone

et al. 2009

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“…This method has previously been validated for beat-to-beat measurements (Innes, Mills, Noble, Murphy, Pugh, Shore & Guz, 1987). Blood pressure was measured in the digital artery of the middle finger using a servo-controlled finger cuff (Finapres, Ohmeida, Englewood, CO, USA).…”

Section: Measurementsmentioning

confidence: 99%

Within‐breath modulation of left ventricular function during normal breathing and positive‐pressure ventilation in man.

Innes

Cort

Kox

et al. 1993

The Journal of Physiology

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SUMMARY1. To investigate how intrathoracic pressure affects left ventricular function during normal breathing and positive-pressure ventilation, beat-by-beat measurements of left ventricular stroke volume (LVSV; pulsed Doppler ultrasound), heart rate and blood pressure were made in five normal subjects breathing actively and then undergoing passive positive-pressure ventilation.2. To assess the within-breath effects of positive-pressure ventilation on left ventricular function in the clinical setting, further measurements were made in six patients sedated, paralysed and ventilated because of brain injuries, who had no disease of the heart or lungs.3. In the normal subjects, there was minimal phasic variation in LVSV during positive-pressure ventilation with the subject passive. Heart rate and blood pressure also stayed relatively constant throughout the ventilator cycle. During active breathing at the same depth and rate, there were large phasic respiratory variations in LVSV, with the lowest values occurring during inspiration.4. In the paralysed and unconscious patients, an increase in LVSV was associated with the increase in airway pressure which occurred during lung inflation; however, the phase lag between the rise in airway pressure and the rise in LVSV varied widely between patients. These changes occurred whether or not sinus arrhythmia was present.5. Addition of 4-6 +1 cmH20 of positive end-expiratory pressure (PEEP) did not increase the within-breath LVSV variations, but resulted in a mean depression of LVSV of 5-4 % (paired t test, P = 0035).6. The smaller variations in LVSV during positive-pressure ventilation compared to normal breathing in the conscious subjects may reflect (a) the smaller magnitude of positive, compared to negative, pleural pressure excursions which accompany a given tidal volume, and (b) an asymmetry between the effects of positive and negative pleural pressure on the heart. 7. The prominent effects of positive-pressure ventilation on LVSV in unconscious patients, compared to the minimal effects seen in ventilated normal subjects, may result from reduced lung compliance and a degree of pulmonary vascular congestion in the patients which was undetectable clinically or radiologically.

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“…The Doppler ultrasound technique has made it possible to record stroke volume (SV) directly, non-invasively and on a beat-to-beat basis (Loeppky, Greene, Hoekenga, Caprihan & Luft, 1981; Ihlen, Amlie, Dale, Forfang, Nitter-Hauge, Otterstad, Simonsen & Myhre, 1984; Mehta, Iyawe, Cummin, Bayley, Saunders & Bennett, 1985; Innes, Mills, Noble, Murphy, Pugh, Shore & Guz, 1987), and the technique has been applied also to the dynamic phase at the onset of exercise (Loeppky et al 1981; Cummin, Iyawe, Mehta & Saunders, 1986;Adams, Guz, Innes & Murphy, 1987). However, technical problems have apparently hitherto prevented a full exploitation of the potential time resolution of the method.…”

Section: Introductionmentioning

confidence: 99%

Dynamics and dimensions of cardiac output changes in humans at the onset and at the end of moderate rhythmic exercise.

Eriksen

Waaler

Walløe

et al. 1990

The Journal of Physiology

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SUMMARY1. An improved Doppler ultrasound technique was used to measure stroke volume (SV) and cardiac output (CO) on a beat-to-beat basis in a group of supine humans before, during and after periods of standardized, rhythmic exercise, involving the quadriceps muscle groups on both sides. The development of CO on such bouts of exercise was compared to Doppler ultrasound records of the simultaneous femoral arterial flow (FF) response.2. Records of CO at rest revealed spontaneous fluctuations around a mean level, with differences between the minimal and maximal values of the order of 11 min'. The mean CO level at rest again varied considerably from one day to another and from test run to test run.3. Upon start of exercise an immediate and rapid increase in heart rate (HR) and CO took place. The entire increase, the size of which varied appreciably from test run to test run, was completed within 10-15 s. No or only minor changes were seen in the mean SV level during the exercise periods.4. The time course of the increase in FF was indistinguishable from that of the increase in CO, which occurred without any detectable delay relative to the changes in FF. These closely parallel developments indicate a tight regulatory coupling between the two types of flow changes.5. In the majority of tests the total and two-sided increase in FF seen in the steady-state situation in the last part of an exercise period was significantly larger than the recorded increase in CO. This discrepancy implies that some redistribution of flow from tissues other than the working muscles might take place, even at this moderate level of work.

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Validation of beat by beat pulsed Doppler measurements of ascending aortic blood velocity in man

Cited by 40 publications

References 0 publications

Evaluation of Noninvasive Methods to Assess Wave Reflection and Pulse Transit Time From the Pressure Waveform Alone

Evaluation of Noninvasive Methods to Assess Wave Reflection and Pulse Transit Time From the Pressure Waveform Alone

Within‐breath modulation of left ventricular function during normal breathing and positive‐pressure ventilation in man.

Dynamics and dimensions of cardiac output changes in humans at the onset and at the end of moderate rhythmic exercise.

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