Key result
Novel multiparameter method CCPm strongly correlates with traditional TCD for determining critical closing pressure.
Why the study?
Does a novel multiparameter method (CCPm) correlate with traditional TCD calculations (CCP1) for determining critical closing pressure in a rabbit model?
Does a novel multiparameter method (CCPm) correlate with traditional TCD calculations (CCP1) for determining critical closing pressure in a rabbit model?
A novel multiparameter mathematical model for critical closing pressure correlates well with traditional methods and avoids non-physiological negative values during hypercapnia-induced hyperemia.
Answers are grounded in this paper and cite their sources.
May enable artifact-free CCP estimation in hyperemic animal models; leaves open translation to human TCD monitoring.
Critical closing pressure (CCP) is the arterial blood pressure (ABP) at which brain vessels collapse and cerebral blood flow (CBF) ceases. Using the concept of impedance to CBF, CCP can be expressed with brain-monitoring parameters: cerebral perfusion pressure (CPP), ABP, blood flow velocity (FV), and heart rate. The novel multiparameter method (CCPm) was compared with traditional transcranial Doppler (TCD) calculations of CCP (CCP1). Digital recordings of ABP, intracranial pressure (ICP), and TCD-based FV from previously published studies of 29 New Zealand White rabbits were reanalyzed. Overall, CCP1 and CCPm showed correlation across wide ranges of ABP, ICP, and PaCO2 (R=0.93, P<0.001). Three physiological perturbations were studied: increase in ICP (n=29) causing both CCP1 and CCPm to increase (P<0.001 for both); reduction of ABP (n=10) resulting in decrease of CCP1 (P=0.006) and CCPm (P=0.002); and controlled increase of PaCO2 (n=8) to hypercapnic levels, which decreased CCP1 and CCPm, albeit insignificantly (P=0.123 and P=0.306 respectively), caused by a spontaneous significant increase in ABP (P=0.025). Multiparameter mathematical model of critical closing pressure explains the relationship of CCP on brain-monitoring variables, allowing the estimation of CCP during cases such as hypercapnia-induced hyperemia, where traditional calculations, like CCP1, often reach negative non-physiological values.
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Varsos et al. (2012) studied this question. Multiparameter method (CCPm) vs. Traditional transcranial Doppler calculations (CCP1) was evaluated on Correlation between CCP1 and CCPm across wide ranges of ABP, ICP, and PaCO2 (R=0.93, p=<0.001). The novel multiparameter method (CCPm) for determining critical closing pressure strongly correlated with traditional transcranial Doppler calculations (R=0.93, P<0.001) across physiological ranges.
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