Doppler estimation of zero flow pressure during changes in downstream pressure in a bench model of a circulation using pulsatile flow*

Athanassiou, L.; Hancock, S. M.; Mahajan, Ravi

doi:10.1111/j.1365-2044.2004.04036.x

Cited by 7 publications

(7 citation statements)

References 22 publications

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“…Fifth, we did not titrate the dose of GTN to BP response, instead choosing to use a fixed-dose GTN patch, so cerebral and systemic hemodynamic measures will have varied somewhat between patients. Finally, we did not directly measure ICP, but rather used an indirect estimate of CPP 9,23 to avoid the need for measuring invasive pressure transducers.…”

Section: Discussionmentioning

confidence: 99%

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Transdermal Glyceryl Trinitrate Lowers Blood Pressure and Maintains Cerebral Blood Flow in Recent Stroke

et al. 2006

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Abstract-High blood pressure (BP) is common in acute stroke and is independently associated with a poor outcome.Lowering BP might improve outcome if it did not adversely affect cerebral blood flow (CBF) or cerebral perfusion pressure. We investigated the effect of glyceryl trinitrate ([GTN] an NO donor) on quantitative CBF, BP, and cerebral perfusion pressure in patients with recent stroke. Eighteen patients with recent (Ͻ5 days) ischemic (nϭ16) or hemorrhagic (nϭ2) stroke were randomly assigned (2:1) to transdermal GTN (5 mg) or control. CBF (global, hemispheric, arterial territory, and lesion, using xenon computed tomography) and BP (peripheral and central) were measured before and 1 hour after treatment with GTN. The effects of GTN on CBF and BP were adjusted for baseline measurements (ANCOVA

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Section: Discussionmentioning

confidence: 99%

“…CPP and ZFP were estimated noninvasively from measures of middle cerebral artery blood flow velocity (FV), assessed using transcranial Doppler, and peripheral BP using the following method 9,23 :…”

Section: Methodsmentioning

confidence: 99%

Transdermal Glyceryl Trinitrate Lowers Blood Pressure and Maintains Cerebral Blood Flow in Recent Stroke

et al. 2006

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“…Estimated cerebral perfusion pressure (CPP) was calculated using a mean of contralateral and ipsilateral cerebral blood flow velocity as follows: 40,41 …”

Section: Haemodynamic Measuresmentioning

confidence: 99%

Amphetamine increases blood pressure and heart rate but has no effect on motor recovery or cerebral haemodynamics in ischaemic stroke: a randomized controlled trial (ISRCTN 36285333)

et al. 2007

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Amphetamine enhances recovery after experimental ischaemia and has shown promise in small clinical trials when combined with motor or sensory stimulation. Amphetamine, a sympathomimetic, might have haemodynamic effects in stroke patients, although limited data have been published. Subjects were recruited 3-30 days post-ischaemic stroke into a phase II randomized (1:1), double-blind, placebo-controlled trial. Subjects received dexamphetamine (5 mg initially, then 10 mg for 10 subsequent doses with 3-or 4-day separations) or placebo in addition to inpatient physiotherapy. Recovery was assessed by motor scales (Fugl-Meyer (FM)), and functional scales (Barthel index (BI) and modified Rankin score (mRS)). Peripheral blood pressure (BP), central haemodynamics and middle cerebral artery blood flow velocity were assessed before, and 90 min after, the first two doses. Thirty-three subjects were recruited, aged 33-88 (mean 71) years, males 52%, 4-30 (median 15) days post stroke to inclusion. Sixteen patients were randomized to placebo and seventeen to amphetamine. Amphetamine did not improve motor function at 90 days; mean (s.d.) FM 37.6 (27.6) vs control 35.2 (27.8) (P ¼ 0.81). Functional outcome (BI, mRS) did not differ between treatment groups. Peripheral and central systolic BP, and heart rate (HR), were 11.2 mm Hg (P ¼ 0.03), 9.5 mm Hg (P ¼ 0.04) and 7 beats per minute (P ¼ 0.02) higher, respectively, with amphetamine, compared with control. A nonsignificant reduction in myocardial perfusion (BUI) was seen with amphetamine. Other cardiac and cerebral haemodynamics were unaffected. Amphetamine did not improve motor impairment or function after ischaemic stroke but did significantly increase BP and HR without altering cerebral haemodynamics.

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“…The middle cerebral arteries in the ipsilateral and contralateral hemispheres were identified and measurements were made at the observed peak systolic flow velocity (FV); measurements included systolic, mean, and diastolic flow velocity and pulsatility index. CPP and ZFP were subsequently calculated for each time point using the following formulae [14,15]:…”

Section: Transcranial Dopplermentioning

confidence: 99%

“…Cerebral perfusion pressure (CPP) is a derived measurement and is equivalent to the mathematical difference between mean arterial pressure (MAP) and ZFP. Some vasoactive drugs may reduce ZFP by inducing cerebral venodilatation, thereby increasing CPP [14,15].…”

Section: Introductionmentioning

confidence: 99%

Effect of Telmisartan on Cerebral and Systemic Haemodynamics in Patients with Recent Ischaemic Stroke: A Randomised Controlled Trial

et al. 2013

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High blood pressure (BP) is common in acute stroke and is independently associated with a poor outcome. Lowering BP might improve outcome if cerebral blood flow (CBF) is unaffected in the presence of dysfunctional autoregulation. We investigated the effect of telmisartan on systemic and cerebral haemodynamics in patients with recent stroke. Patients with ischaemic stroke (<5 days) were randomised to 90 days of telmisartan (80 mg) or placebo. CBF (primary outcome) was measured using xenon CT at baseline and 4 hours. BP and transcranial doppler (TCD) were performed at baseline, 4 hours after-treatment, and on days 4, 7, and 90. Cerebral perfusion pressure and zero filling pressure (ZFP) were calculated. Of a planned 24 patients, 17 were recruited. Telmisartan significantly accentuated the fall in systolic and diastolic BP over 90 days (treatment-time interaction = 0.047, = 0.003, resp.) but did not alter BP at 4 hours after treatment (171/99 versus 167/87 mmHg), CBF, or CBF velocity. ZFP was significantly lower in the treatment group ( = 0.018). Impairment at 7 days and dependency at 90 days did not differ between the groups. In this underpowered study, telmisartan did not significantly alter BP or CBF after the first dose. Telmisartan reduced BP over the subsequent 90 days and significantly lowered ZFP. This trial is registered with ISRCTN 41456162.

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Doppler estimation of zero flow pressure during changes in downstream pressure in a bench model of a circulation using pulsatile flow*

Cited by 7 publications

References 22 publications

Transdermal Glyceryl Trinitrate Lowers Blood Pressure and Maintains Cerebral Blood Flow in Recent Stroke

Transdermal Glyceryl Trinitrate Lowers Blood Pressure and Maintains Cerebral Blood Flow in Recent Stroke

Amphetamine increases blood pressure and heart rate but has no effect on motor recovery or cerebral haemodynamics in ischaemic stroke: a randomized controlled trial (ISRCTN 36285333)

Effect of Telmisartan on Cerebral and Systemic Haemodynamics in Patients with Recent Ischaemic Stroke: A Randomised Controlled Trial

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