scholarly journals Cerebral Vasospasm Affects Arterial Critical Closing Pressure

2014 ◽  
Vol 35 (2) ◽  
pp. 285-291 ◽  
Author(s):  
Georgios V Varsos ◽  
Karol P Budohoski ◽  
Marek Czosnyka ◽  
Angelos G Kolias ◽  
Nathalie Nasr ◽  
...  
Keyword(s):  
Cerebral Vasospasm ◽  
Vascular Tone ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Vascular Wall ◽  
Wall Tension ◽  
Small Vessels ◽  
Arterial Blood ◽  
Critical Closing Pressure ◽  
Temporal And Spatial ◽  
Closing Pressure

The effect of cerebral vasospasm (CVS) after aneurysmal subarachnoid hemorrhage (SAH) on critical closing pressure (CrCP) has not been fully delineated. Using cerebral impedance methodology, we sought to assess the behavior of CrCP during CVS. As CrCP expresses the sum of intracranial pressure (ICP) and vascular wall tension, we also explored its role in reflecting changes in vascular tone occurring in small vessels distal to spasm. This retrospective analysis was performed using recordings from 52 patients, diagnosed with CVS through transcranial Doppler measurements. Critical closing pressure was calculated noninvasively using arterial blood pressure and blood flow velocity. Outcome was assessed at both discharge and 3 months after ictus with the Glasgow Outcome Scale. The onset of CVS caused significant decreases in CrCP ( P=0.025), without any observed significant changes in ICP ( P=0.134). Vasospasm induced asymmetry, with CrCP ipsilateral to CVS becoming significantly lower than contralateral ( P=0.025). Unfavorable outcomes were associated with a significantly lower CrCP after the onset of CVS (discharge: P=0.014; 3 months after SAH: P=0.020). Critical closing pressure is reduced in the presence of CVS in both temporal and spatial assessments. As ICP remained unchanged during CVS, reduced CrCP most probably reflects a lower wall tension in dilated small vessels distal to spasm.

Differences in the dynamic cerebrovascular response between stepwise up tilt and down tilt in humans

2001 ◽  
Vol 281 (2) ◽  
pp. H774-H783 ◽  
Author(s):  
Jiro Sato ◽  
Masatoshi Tachibana ◽  
Tsutomu Numata ◽  
Takashi Nishino ◽  
Akiyoshi Konno
Keyword(s):  
Doppler Ultrasonography ◽  
Cerebral Blood Flow Velocity ◽  
Cardiovascular Responses ◽  
Second Order ◽  
Order Model ◽  
Healthy Humans ◽  
Arterial Blood ◽  
Critical Closing Pressure ◽  
Closing Pressure ◽  
Second Order Model

We studied dynamic cerebrovascular responses in eight healthy humans during repetitive stepwise upward tilt (SUT) and stepwise downward tilt (SDT) maneuvers between supine and 70° standing at intervals of 60 s. Mean cerebral blood flow velocity (FVMCA) was measured at the middle cerebral artery (MCA) with transcranial Doppler ultrasonography. Mean arterial blood pressure (ABP) was measured via the radial artery and adjusted at the level of the MCA (ABPMCA). Cerebral critical closing pressure (PCC) was estimated from the systolic-diastolic relationship between FVMCA and ABPMCA. ABPMCA minus PCC was considered the cerebral perfusion pressure (CPP). The tilt maneuvers produced stepwise changes in both CPP and FVMCA. The FVMCA response to SUT was well characterized by a linear second-order model. However, that to SDT presented a biphasic behavior that was described significantly better ( P < 0.05) by the addition of a slowly responding component to the second-order model. This difference may reflect both different cardiovascular responses to SUT or SDT and different cerebrovascular autoregulatory behaviors in response to decreases or increases in CPP.

High-dose intraarterial verapamil in the treatment of cerebral vasospasm after aneurysmal subarachnoid hemorrhage

2008 ◽  
Vol 108 (3) ◽  
pp. 458-463 ◽  
Author(s):  
Janine Keuskamp ◽  
Raj Murali ◽  
Kuo H. Chao
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Cerebral Vasospasm ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Senior Author ◽  
High Dose ◽  
Channel Blockers ◽  
Hemodynamic Stability ◽  
Arterial Blood ◽  
Intracranial Pressures ◽  
Blood Pressures

Object Because oral calcium channel blockers appear to reduce the severity of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH), interest in their application intraarterially has emerged for cases in which noninvasive means of alleviating vasospasm are unsuccessful. Studies to date have been limited to the administration of low intraarterial doses because of concerns about hemodynamic stability and changes in intracranial pressure. These doses, although effective in cases of milder vasospasm, were inadequate in severe cases. The authors present a series of 10 patients with cerebral vasospasm who underwent 12 procedures in which they received ≥ 20 mg of intraarterial verapamil per procedure. Methods A retrospective review was undertaken of all patients who underwent endovascular treatment for cerebral vasospasm due to aneurysmal SAH by the senior author between February 2005 and October 2006. Ten patients were identified who had undergone a total of 12 procedures during which ≥20 mg of intraarterial verapamil had been administered. From angiography reports, anesthesia records, and nursing records, we obtained pre- and postverapamil mean arterial blood pressures (MABPs), heart rates, intracranial pressures (ICPs) (when available), and visible changes in the degree of vasospasm. Results No statistically significant changes in MABP, heart rate, or ICP were observed after administration of ≥ 20 mg of intraarterial verapamil, and the degree of improvement in vasospasm was statistically significant based on our grading system. No correlation was found between the change in hemodynamic parameters and the total dose of verapamil. Conclusions This study indicates that high-dose intraarterial verapamil may be used to treat cerebral vasospasm without compromising hemodynamic stability or increasing ICP.

scholarly journals Frequency Dependence of Cerebrovascular Impedance in Preterm Neonates: A Different View on Critical Closing Pressure

1997 ◽  
Vol 17 (10) ◽  
pp. 1127-1131 ◽  
Author(s):  
Erik Michel ◽  
Stefanie Hillebrand ◽  
Johanna vonTwickel ◽  
Boris Zernikow ◽  
Gerd Jorch
Keyword(s):  
Blood Pressure ◽  
Frequency Response ◽  
Cerebral Blood Flow Velocity ◽  
Preterm Neonates ◽  
Pass Filter ◽  
Arterial Blood ◽  
Critical Closing Pressure ◽  
Cerebrovascular System ◽  
Closing Pressure ◽  
Zero Frequency

The nonproportional relationship between instantaneous arterial blood pressure (BP) and cerebral blood flow velocity (CBFv) is well explained by the concept of critical closing pressure (CCP). We aimed to determine the frequency response of the neonatal cerebrovascular system, and to establish the exact mathematical relationship between cerebrovascular impedance and CCP under physiologic conditions. In 10 preterm neonates (gestational age, 25–32 weeks; birth weight, 685–1,730 g; age 1–7 days) we Doppler-traced CBFv of the internal carotid artery. Blood pressure was traced simultaneously. Critical closing pressure was graphically determined. Cerebrovascular impedance was calculated as the square root of the ratio of the corresponding peaks in the power spectra of BP and CBFv at zero frequency, and at heart rate (H) and harmonics (xH). Uniformly, the impedance between H and 3H (2 to 6 Hz) was reduced about fivefold, compared with the impedance at zero frequency. The cerebrovascular system behaves like a high-pass filter, leading to a reduction of the DC (direct current) component of CBFv (analogous to current) relative to that of the driving force BP (analogous to voltage). The frequency response of cerebrovascular impedance reflects the ratio of CCP and DC BP. A mathematical derivation of this relationship is given matching the observed results. Thus, both the CCP and the impedance approach are valid.

scholarly journals A noninvasive estimation of cerebral perfusion pressure using critical closing pressure

2015 ◽  
Vol 123 (3) ◽  
pp. 638-648 ◽  
Author(s):  
Georgios V. Varsos ◽  
Angelos G. Kolias ◽  
Peter Smielewski ◽  
Ken M. Brady ◽  
Vassilis G. Varsos ◽  
...  
Keyword(s):  
Cerebral Perfusion Pressure ◽  
Cerebral Perfusion ◽  
Perfusion Pressure ◽  
Estimation Error ◽  
Cohort Analysis ◽  
Area Under The Curve ◽  
Impedance Method ◽  
Arterial Blood ◽  
Critical Closing Pressure ◽  
Closing Pressure

OBJECT Cerebral blood flow is associated with cerebral perfusion pressure (CPP), which is clinically monitored through arterial blood pressure (ABP) and invasive measurements of intracranial pressure (ICP). Based on critical closing pressure (CrCP), the authors introduce a novel method for a noninvasive estimator of CPP (eCPP). METHODS Data from 280 head-injured patients with ABP, ICP, and transcranial Doppler ultrasonography measurements were retrospectively examined. CrCP was calculated with a noninvasive version of the cerebrovascular impedance method. The eCPP was refined with a predictive regression model of CrCP-based estimation of ICP from known ICP using data from 232 patients, and validated with data from the remaining 48 patients. RESULTS Cohort analysis showed eCPP to be correlated with measured CPP (R = 0.851, p < 0.001), with a mean ± SD difference of 4.02 ± 6.01 mm Hg, and 83.3% of the cases with an estimation error below 10 mm Hg. eCPP accurately predicted low CPP (< 70 mm Hg) with an area under the curve of 0.913 (95% CI 0.883–0.944). When each recording session of a patient was assessed individually, eCPP could predict CPP with a 95% CI of the SD for estimating CPP between multiple recording sessions of 1.89–5.01 mm Hg. CONCLUSIONS Overall, CrCP-based eCPP was strongly correlated with invasive CPP, with sensitivity and specificity for detection of low CPP that show promise for clinical use.

scholarly journals Noninvasive optical monitoring of critical closing pressure and arteriole compliance in human subjects

2017 ◽  
Vol 37 (8) ◽  
pp. 2691-2705 ◽  
Author(s):  
Wesley B Baker ◽  
Ashwin B Parthasarathy ◽  
Kimberly P Gannon ◽  
Venkaiah C Kavuri ◽  
David R Busch ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Continuous Monitoring ◽  
Human Subjects ◽  
Correlation Spectroscopy ◽  
Invasive Technique ◽  
Windkessel Model ◽  
Arterial Blood ◽  
Critical Closing Pressure ◽  
Closing Pressure

The critical closing pressure ( CrCP) of the cerebral circulation depends on both tissue intracranial pressure and vasomotor tone. CrCP defines the arterial blood pressure ( ABP) at which cerebral blood flow approaches zero, and their difference ( ABP −  CrCP) is an accurate estimate of cerebral perfusion pressure. Here we demonstrate a novel non-invasive technique for continuous monitoring of CrCP at the bedside. The methodology combines optical diffuse correlation spectroscopy (DCS) measurements of pulsatile cerebral blood flow in arterioles with concurrent ABP data during the cardiac cycle. Together, the two waveforms permit calculation of CrCP via the two-compartment Windkessel model for flow in the cerebral arterioles. Measurements of CrCP by optics (DCS) and transcranial Doppler ultrasound (TCD) were carried out in 18 healthy adults; they demonstrated good agreement (R = 0.66, slope = 1.14 ± 0.23) with means of 11.1 ± 5.0 and 13.0 ± 7.5 mmHg, respectively. Additionally, a potentially useful and rarely measured arteriole compliance parameter was derived from the phase difference between ABP and DCS arteriole blood flow waveforms. The measurements provide evidence that DCS signals originate predominantly from arteriole blood flow and are well suited for long-term continuous monitoring of CrCP and assessment of arteriole compliance in the clinic.

THE MEASUREMENT OF BLOOD PRESSURE, THE CRITICAL OPENING PRESSURE, AND THE CRITICAL CLOSING PRESSURE OF DIGITAL VESSELS UNDER VARIOUS CIRCUMSTANCES

1965 ◽  
Vol 43 (6) ◽  
pp. 979-993 ◽  
Author(s):  
Peter Gaskell
Keyword(s):  
Blood Pressure ◽  
Nerve Block ◽  
Spectroscopic Method ◽  
Spectroscopic Technique ◽  
Opening Pressure ◽  
Small Vessels ◽  
Critical Opening ◽  
Critical Closing Pressure ◽  
Digital Nerve Block ◽  
Closing Pressure

A spectroscopic technique for the estimation of the critical opening pressure (COP) or critical closing pressure (CCP) of small vessels in the finger is described. The spectroscopic method of estimation of the systolic blood pressure, which is part of the technique and which involves the detection of reappearance of oxyhemoglobin absorption bands in the spectrum of reflected light from the skin distal to a blood pressure cuff that is slowly deflated, was compared to the auscultatory technique in 38 subjects on 53 occasions and gave the same results. The COP of small vessels in the finger estimated by the spectroscopic technique was decreased by body heating and by digital nerve block as had been previously shown by the microscopical method. The COP of vessels in the finger after digital nerve block in 43 normotensive young women between the ages of 18 and 22 years ranged from 2 to 19 mm Hg with a mean of 9.5 ± 4.6 (S.D.) mm Hg. When the COP was estimated in many of the same subjects after preparation as for measurement of the basal metabolic rate, in most cases it fell within the range of values obtained after nerve block. The COP in 26 subjects ranged from 1 to 22 mm Hg with a mean of 10.9 ± 5.0 (S.D.). The values for CCP estimated by the spectroscopic method in 81 individuals were not significantly different from those for COP estimated on the same occasion.

scholarly journals Critical Closing Pressure: Comparison of Three Methods

2009 ◽  
Vol 29 (5) ◽  
pp. 987-993 ◽  
Author(s):  
Jorge A López-Magañna ◽  
Hugh K Richards ◽  
Danila K Radolovich ◽  
Dong-Joo Kim ◽  
Peter Smielewski ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Cardiac Arrest ◽  
Arterial Blood Pressure ◽  
Transcranial Doppler ◽  
Cerebrovascular Circulation ◽  
Waveform Analysis ◽  
Arterial Blood ◽  
Pressure Threshold ◽  
Critical Closing Pressure ◽  
Closing Pressure

Critical closing pressure (CCP) is an arterial pressure threshold below which small arterial vessels collapse. Our aim was to compare different methods to estimate CCP in the cerebrovascular circulation using the relationships between transcranial Doppler flow velocity (FV), laser-Doppler flux (LDF), and arterial blood pressure (ABP). A total of 116 experiments in rabbits were analyzed retrospectively. At the end of each recording, cardiac arrest (CA) was induced. Arterial blood pressure in femoral artery, basilar artery FV, cortical blood LDF, intracranial pressure (ICP) was recorded. Critical closing pressure was estimated using linear regression between decreasing mean ABP values, FV, and LDF during CA. In addition, CCP was calculated from FV waveform just before CA. The correlation between CCP evaluated using LDF and FV during CA was 0.98 ( P < 0.0001). The correlation between CCP measured during CA and CCP estimated from the transcranial Doppler ultrasonography (TCD) waveform was weaker ( R=0.39; P <0.001), with CCP calculated from waveform being significantly greater than CCP from CA (median difference 9 mm Hg; P < 0.003). Critical closing pressures obtained from FV waveform and CA correlated with mean ICP before CA ( R = 0.40; P = 0.001). In conclusion strong correlation exists between CCP values obtained by means of FV and LDF during cardiac arrest. However, predictions of CCP using TCD waveform analysis show substantial differences from values of CCP recorded during cardiac arrest.

scholarly journals Cerebral critical closing pressure and resistance-area product: the influence of dynamic cerebral autoregulation, age, and sex

2021 ◽  
pp. 0271678X2110041
Author(s):  
Ronney B Panerai ◽  
Victoria J Haunton ◽  
Osian Llwyd ◽  
Jatinder S Minhas ◽  
Emmanuel Katsogridakis ◽  
...  
Keyword(s):  
Cerebral Autoregulation ◽  
Function Analysis ◽  
Step Response ◽  
Arterial Blood ◽  
Transfer Function Analysis ◽  
Critical Closing Pressure ◽  
Area Product ◽  
Closing Pressure ◽  
Dynamic Cerebral Autoregulation ◽  
Step Responses

Instantaneous arterial pressure-flow (or velocity) relationships indicate the existence of a cerebral critical closing pressure (CrCP), with the slope of the relationship expressed by the resistance-area product (RAP). In 194 healthy subjects (20–82 years, 90 female), cerebral blood flow velocity (CBFV, transcranial Doppler), arterial blood pressure (BP, Finapres) and end-tidal CO2 (EtCO2, capnography) were measured continuously for five minutes during spontaneous fluctuations of BP at rest. The dynamic cerebral autoregulation (CA) index (ARI) was extracted with transfer function analysis from the CBFV step response to the BP input and step responses were also obtained for the BP-CrCP and BP-RAP relationships. ARI was shown to decrease with age at a rate of −0.025 units/year in men (p = 0.022), but not in women (p = 0.40). The temporal patterns of the BP-CBFV, BP-CrCP and BP-RAP step responses were strongly influenced by the ARI (p < 0.0001), but not by sex. Age was also a significant determinant of the peak of the CBFV step response and the tail of the RAP response. Whilst the RAP step response pattern is consistent with a myogenic mechanism controlling dynamic CA, further work is needed to explore the potential association of the CrCP step response with the flow-mediated component of autoregulation.

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