Computerized evaluation of blood flow measurement indices using doppler ultrasound

Saini, Vasant D.; Maulik, Debabrata; Nanda, Navin C.; Rosenzweig, Mark S.

doi:10.1016/0301-5629(83)90011-x

Cited by 13 publications

(2 citation statements)

References 4 publications

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“…Maximizing the

\overset{P}{true}

signal permits the assumption that the entire cross‐sectional area of the MCA is fully captured within the sample volume of the TCD's transmitted signal and that any changes in the

\overset{P}{true}

signal that ensue represent a change in MCA calibre (Deverson & Evans, ). Though no in vivo validation studies have been performed, changes in the

\overset{P}{true}

signal as an index of changes in cross‐sectional area of the insonated artery has been validated using flow phantoms (Deverson & Evans, ; Hatab et al., ; Saini, Maulik, Nanda, & Rosenzweig, ), which remain the gold standard for validation of non‐invasive techniques used in humans to assess CBF such as duplex ultrasonography (Rominger et al., ) and neuroimaging (Taviani et al., ). Finally, to minimize the impact of TCD probe movement on signal quality, participants were instructed to remain as still as possible during the entire experimental protocol.…”

Section: Methodsmentioning

confidence: 99%

Vascular responses to hypoxia are not impaired in obstructive sleep apnoea patients free of overt cardiovascular disease

Beaudin

Hanly

Raneri

et al. 2019

Experimental Physiology

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New Findings What is the central question of this study?Does treatment of obstructive sleep apnoea (OSA) with nocturnal oxygen or continuous positive airway pressure (CPAP) improve hypoxic vascular responses, which are reportedly impaired in OSA? What is the main finding and its importance?Cerebrovascular and cardiovascular hypoxic responses were not impaired in OSA patients free of overt cardiovascular disease and known risk factors, and were not altered by nocturnal oxygen or CPAP treatment. We conclude that this OSA patient phenotype has normal vascular responses to hypoxia and is unlikely to obtain long term cardiovascular benefits from nocturnal oxygen or CPAP therapy. Abstract Cerebral blood flow (CBF) and cardiovascular responses to hypoxia are reportedly impaired in obstructive sleep apnoea (OSA) patients and corrected by continuous positive airway pressure (CPAP), beneficial effects that are ascribed to correction of OSA‐related intermittent hypoxia (IH). However, CPAP corrects both IH and ancillary OSA features (i.e. intermittent hypercapnia, sympathetic activation, blood pressure surges, negative intrathoracic pressure swings and sleep fragmentation). Whether correction of these ancillary OSA features contribute to CPAP's beneficial effects on vascular hypoxic responses is unknown. Nocturnal oxygen corrects OSA‐induced IH, but apnoeas and ancillary features persist. Thus, we examined the effects of nocturnal oxygen and CPAP on cerebrovascular and cardiovascular hypoxic responses in untreated OSA patients. Responses were assessed in 52 OSA patients free of overt cardiovascular disease and known risk factors at baseline, after 2 weeks of nocturnal oxygen (n = 26) or no treatment (n = 26), and after ∼4 weeks of CPAP treatment (n = 40). Twenty‐two age‐matched controls were assessed at baseline and follow‐up visits. Resting, isocapnic euoxia mean blood pressure was decreased following nocturnal oxygen (−3.6 ± 6.0 mmHg; P = 0.006) and CPAP (−4.5 ± 7.5 mmHg; P < 0.001) while cerebrovascular conductance was increased with CPAP (P = 0.001). However, these changes were not different from controls. Unexpectedly, OSA patients and controls had similar hypoxic vascular responses at baseline that were not changed by either nocturnal oxygen or CPAP. We conclude that OSA patients free of overt cardiovascular disease and known risk factors did not have impaired cerebrovascular or cardiovascular responses to hypoxia and are unlikely to obtain long term cardiovascular benefits from nocturnal oxygen or CPAP therapy.

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“…Maximizing the

\overset{P}{true}

signal permits the assumption that the entire cross‐sectional area of the MCA is fully captured within the sample volume of the TCD's transmitted signal and that any changes in the

\overset{P}{true}

signal that ensue represent a change in MCA calibre (Deverson & Evans, ). Though no in vivo validation studies have been performed, changes in the

\overset{P}{true}

Section: Methodsmentioning

confidence: 99%

Vascular responses to hypoxia are not impaired in obstructive sleep apnoea patients free of overt cardiovascular disease

Beaudin

Hanly

Raneri

et al. 2019

Experimental Physiology

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“…2), it has been difficult to identify a single index that characterizes the "most representative" velocity. We approached this problem by building on the work of Saini et al (31), who proposed three useful Doppler spectrum indices: the maximum significant velocity VMs, the velocity of dominant energy VDE, and the mean velocity V M . To evaluate specific spectral indices, we performed an experimental PUDVM study (14) of well-prescribed steady (Poiseuille) flows in tiny straight tubes.…”

Section: Instrument Developmentmentioning

confidence: 99%

Pulsed ultrasound doppler velocimetry in the assessment of microvascular hemodynamics

Blair

Brown

Greene

1988

Journal Orthopaedic Research

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Pulsed ultrasonic Doppler velocimetry (20 MHz) (PUDVM) has evolved considerably in the last 10 years. Engineering development has resulted in a computer-controlled vessel-scanning instrument whose backscattered frequency shift spectra are analyzed using fast Fourier transforms (FFT). Benchtop and theoretic studies indicate accurate (error less than 5%) velocity and volumetric flow rate measurements in vessels with a lumen diameter as small as 1.2 mm. Clinical application of the PUDVM has provided transcutaneous measurements of blood flow variables in normal human digital arteries. Experimental application to arteries 1.0-1.5 mm has provided information on the hemodynamic effects of topical vasodilators, standard microarteriorrhaphy, variations in microvascular technique, interpositional grafts, and early wound repair. With improving computer capabilities and technical modifications, the PUDVM will be an increasingly important tool in clinical and experimental microsurgery.

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Spectral Doppler Sonography: Waveform Analysis and Hemodynamic Interpretation

Maulik

Doppler Ultrasound in Obstetrics and Gynecology

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Computerized evaluation of blood flow measurement indices using doppler ultrasound

Cited by 13 publications

References 4 publications

Vascular responses to hypoxia are not impaired in obstructive sleep apnoea patients free of overt cardiovascular disease

Vascular responses to hypoxia are not impaired in obstructive sleep apnoea patients free of overt cardiovascular disease

Pulsed ultrasound doppler velocimetry in the assessment of microvascular hemodynamics

Spectral Doppler Sonography: Waveform Analysis and Hemodynamic Interpretation

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