Clinical study of continuous non-invasive cerebrovascular autoregulation monitoring in neurosurgical ICU

Ragauskas, Arminas; Daubaris, Gediminas; Petkus, Vytautas; Ragaišis, Vytautas; Ursino, Mauro

doi:10.1007/3-211-32318-x_75

Cited by 20 publications

(23 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…20 This measurement was then used to measure vascular reactivity as a phase shift between the relative blood volume and the ABP changes at the respiratory frequency as opposed to analyzing at the frequency of slow waves as is done with the PRx and the HVx. 6 The theoretical advantage of using respiratory frequency waveform analysis is the regular periodicity when compared with the sporadic nature of slow waves. However, the phase shift between CBV and ABP resulting from vascular reactivity is "incomplete" at this frequency (that is to say that the high-pass filter used to describe the effect of autoregulation on ABP-CBV transmission has its transition band around this frequency).…”

Section: Discussionmentioning

confidence: 99%

“…3,4 In contrast, in assessing vascular reactivity, the effect of changes in ABP on a surrogate measure of cerebral blood volume (CBV) is measured. 5,6 These low-frequency changes in CBV are attributed to the volume changes caused by the dynamic collective vascular radius. When the vasculature is pressure passive, low-frequency CBV waves are coherent and in phase with the ABP.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Cerebrovascular Reactivity Measured by Near-Infrared Spectroscopy

Lee

Kibler

Benni

et al. 2009

Stroke

177

215

View full text Add to dashboard Cite

Background and Purpose-The pressure reactivity index (PRx) describes cerebral vessel reactivity by correlation of slow waves of intracranial pressure (ICP) and arterial blood pressure. In theory, slow changes in the relative total hemoglobin (rTHb) measured by near-infrared spectroscopy are caused by the same blood volume changes that cause slow waves of ICP. Our objective was to develop a new index of vascular reactivity, the hemoglobin volume index (HVx), which is a low-frequency correlation of arterial blood pressure and rTHb measured with near-infrared spectroscopy. Methods-Gradual hypotension was induced in piglets while cortical laser-Doppler flux was monitored. ICP was monitored, and rTHb was measured continuously using reflectance near-infrared spectroscopy. The HVx was recorded as a moving linear correlation between slow waves (20 to 300 seconds) of arterial blood pressure and rTHb.

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Cerebrovascular Reactivity Measured by Near-Infrared Spectroscopy

Lee

Kibler

Benni

et al. 2009

Stroke

177

215

View full text Add to dashboard Cite

show abstract

“…22,23 Thus, pulse waves occur in passive frequencies, respiratory waves of ABP occur in the transition between passive and reactive frequencies, and slow waves of ABP occur in the reactive frequency bandwidth. 24,25 Continuous monitoring of autoregulation requires a repetitive change in ABP at a frequency that is normally autoregulated and an assessment of CBF change at the same frequency. 26,27 Frequency domain analysis can quantify ABP/CBF wave relationships in a frequency-specific manner.…”

Section: Discussionmentioning

confidence: 99%

Relationship between cerebrovascular dysautoregulation and arterial blood pressure in the premature infant

et al. 2011

View full text Add to dashboard Cite

Objective: To evaluate cerebrovascular autoregulation as a function of arterial blood pressure (ABP) in the critically ill, premature infant.Study Design: A prospective observational pilot study was conducted in two tertiary care Neonatal Intensive-Care Units. Premature infants (n ¼ 23, p30 weeks estimated gestational age with invasive ABP monitoring) were enrolled and received routine care while undergoing continuous autoregulation monitoring, using the cerebral oximetry index (COx). The COx is a moving, linear correlation coefficient between cortical reflectance oximetry and ABP. COx values were stratified as a function of ABP for individual subject recordings and for the cohort.Result: The mean duration of autoregulation monitoring was 3.2 days (median: 2.97, range: 0.61-3.99). A total of 10 of 23 (43%) developed intraventricular hemorrhage and 1 of 23 (4%) developed periventricular leukomalacia by head ultrasound. No association was found between neurologic injury and percentage of the monitoring periods with autoregulation impairment (defined as COx>0.5). Lower ABP was associated with dysautoregulation (higher COx values, P<0.01). The percentage of time with impaired autoregulation was greater with lower ABP (P ¼ 0.013, Spearman r ¼ 0.51).Conclusion: All infants studied had periods with intact and periods with impaired cerebrovascular autoregulation, measured with the COx. Low ABP was associated with impaired autoregulation.

show abstract

“…Intrathoracic pressure changes, whether from spontaneous breathing or mechanical ventilation, cause low-amplitude changes in ABP, and previous studies have attempted to use respiratory ABP waves to measure autoregulation (14,16). However, typical respiratory frequencies are too fast to fully engage the autoregulatory mechanism.…”

Section: Discussionmentioning

confidence: 99%

“…However, typical respiratory frequencies are too fast to fully engage the autoregulatory mechanism. As a result, the phaseangle difference between ABP and cerebral blood volume (or flow), measured at the respiratory frequency, can only weakly discriminate intact from impaired autoregulation (ϳ30°-70°i ntact vs. ϳ0°-50°impaired) (11,12,16). The high-pass frequency response of the autoregulatory mechanism suggests Values are presented as median and IQR.…”

Section: Discussionmentioning

confidence: 99%

Positive end-expiratory pressure oscillation facilitates brain vascular reactivity monitoring

Brady

Easley

Kibler

et al. 2012

Journal of Applied Physiology

View full text Add to dashboard Cite

Brady KM, Easley RB, Kibler K, Kaczka DW, Andropoulos D, Fraser CD 3rd, Smielewski P, Czosnyka M, Adams GJ, Rhee CJ, Rusin CG. Positive end-expiratory pressure oscillation facilitates brain vascular reactivity monitoring. J Appl Physiol 113: 1362-1368, 2012. First published September 13, 2012 doi:10.1152/japplphysiol.00853.2012.-The pressure reactivity index (PRx) identifies optimal cerebral perfusion pressure after traumatic brain injury. We describe a method to improve PRx precision by induced variations in arterial blood pressure (ABP) using positive end-expiratory pressure (PEEP) modulation (iPRx). Neonatal swine (n ϭ 10) were ventilated with static PEEP and then with PEEP oscillated between 5 and 10 cmH2O at a frequency of 1/min. PRx was recorded as a moving correlation coefficient between ABP and intracranial pressure (ICP) from spontaneous ABP activity (0.05-0.003 Hz) during static PEEP. iPRx was similarly recorded with PEEP oscillation-induced ABP waves. The lower limit of autoregulation (LLA) was delineated with continuous cortical laser Doppler flux monitoring. PEEP oscillation increased autoregulation-monitoring precision. The ratios of median absolute deviations to range of possible values for the PRx and iPRx were 9.5% (8.3-13.7%) and 6.2% (4.2-8.7%), respectively (P ϭ 0.006; median, interquartile range). The phase-angle difference between ABP and ICP above LLA was 161°(150°-166°) and below LLA, Ϫ31°(Ϫ42°to 12°, P Ͻ 0.0001). iPRx above LLA was Ϫ0.42 (Ϫ0.67 to Ϫ0.29) and below LLA, 0.32 (0.22-0.43, P ϭ 0.0004). A positive iPRx was 97% specific and 91% sensitive for perfusion pressure below LLA. PEEP oscillation caused stable, low-frequency ABP oscillations that reduced noise in the PRx. Safe translation of these findings to clinical settings is expected to yield more accurate and rapid delineation of individualized optimal perfusion-pressure goals for patients. cerebrovascular autoregulation; pressure reactivity; positive end-expiratory pressure; neonatal CEREBROVASCULAR PRESSURE AUTOREGULATION is a vital, homeostatic mechanism in the mammalian brain that constrains cerebral blood flow (CBF) during changes in arterial blood pressure (ABP). Dynamic cerebrovascular resistance (CVR), also known as pressure reactivity, mediates autoregulation.The pressure reactivity index (PRx) was first described in 1997 as a means of monitoring cerebrovascular reactivity by moving correlation between slow waves (0.05-0.008 Hz) of ABP and intracranial pressure (ICP) (9). When autoregulation is intact, vascular constriction occurs during increased ABP, and vascular dilatation occurs during decreased ABP. Dilatation and constriction of the cerebral vasculature due to autoregulation can be trended by ICP monitoring: ICP increases during vasodilation and decreases during vasoconstriction (13). Therefore, positive ABP-ICP correlation (positive PRx) indicates pressure-passive cerebral vasculature, a state seen when cerebral perfusion pressure (CPP) is either excessive or inadequate for cerebrovascular autoregulation. Convers...

show abstract

Clinical study of continuous non-invasive cerebrovascular autoregulation monitoring in neurosurgical ICU

Cited by 20 publications

References 8 publications

Cerebrovascular Reactivity Measured by Near-Infrared Spectroscopy

Cerebrovascular Reactivity Measured by Near-Infrared Spectroscopy

Relationship between cerebrovascular dysautoregulation and arterial blood pressure in the premature infant

Positive end-expiratory pressure oscillation facilitates brain vascular reactivity monitoring

Contact Info

Product

Resources

About