My Ph.D. research at the University of Cambridge focused on modelling of brain haemodynamics, particularly describing a terminal situation of cerebral circulation, associated with ischemic strokes. A new methodology was created which can be used for estimating brain’s zero-flow pressure or critical closing pressure (CrCP): a critical threshold for arterial blood pressure (ABP). If ABP falls below CrCP, the local blood pressure inside small vessels (microcirculation) is no longer adequate to keep them open, leading them to a collapse, ceasing blood flow.
The new methodology eliminated the main drawback of previous CrCP methods, which were presenting non-physiological negative values; CrCP can now instead be considered as a reliable tool for physicians. A new CrCP-based mechanism was further introduced, which can quantify the ischemic risk for a patient during haemodynamic changes, like intracranial hypertension or arterial hypotension. In neurointensive care, this mechanism might provide a reference point to guidance of treatment in terms of terminal ischemia associated with collapsing vessels.
Based on this mechanism, the phenomenon of absence of diastolic blood flow was explained as distally collapsed small cerebral vessels, associated with ABP going below CrCP during diastole, possibly then enhancing our understanding of this phenomenon, which could lead to an imminent circulatory arrest and brain death.
1.Cerebral Critical Closing Pressure During Infusion Tests. Acta Neurochir Suppl. May 2016; 122:215-20.
2.Intraspinal Pressure and Spinal Cord Perfusion Pressure after Spinal Cord Injury: an Observational Study. J Neurosurg Spine. Aug 2015; 14:1-9.
3.Cerebral Critical Closing Pressure in Hydrocephalus Patients undertaking Infusion Tests. Neurological Research. Aug 2015; 37(8):674-82.
4.Cerebral Vasospasm affects Arterial Critical Closing Pressure. Journal of Cerebral Blood Flow & Metabolism. Feb 2015; 35(2):285-91.
5.A non-invasive estimation of Cerebral Perfusion Pressure using Critical Closing Pressure. Journal of Neurosurgery. Jan 2015; 9:1-11.
6.Relationship of Vascular Wall Tension and Autoregulation following Traumatic Brain Injury. Neurocritical Care. Oct 2014; 21(2):266-74.
7.Cessation of Diastolic Cerebral Blood Flow Velocity - the role of Critical Closing Pressure. Neurocritical Care. Feb 2014; 20(1):40-8.
8.Model-based Indices describing Cerebrovascular Dynamics. Neurocritical Care. Feb 2014; 20(1):142-57.
9.Critical Closing Pressure during Intracranial Pressure Plateau Waves. Neurocritical Care. Jun 2013; 18(3):341-8.
10.Critical Closing Pressure determined with a Model of Cerebrovascular Impedance. Journal of Cerebral Blood Flow & Metabolism. Feb 2013; 33(2):235-43.
1.Czosnyka et al. Waveform Analysis of Intraspinal Pressure After Traumatic Spinal Cord Injury: An Observational Study (O-64). Acta Neurochir Suppl. May 2016; 122:335-8.
2.Werndle et al. Measurement of Intraspinal Pressure After Spinal Cord Injury: Technical Note from the Injured Spinal Cord Pressure Evaluation Study. Acta Neurochir Suppl. May 2016; 122:323-8.
3.Rhee et al. The Ontogeny of Cerebrovascular Critical Closing Pressure. Acta Neurochir Suppl. May 2016; 122:249-53.
4.Liu et al. Derangement of Cerebral Blood Flow Autoregulation During Intracranial Pressure Plateau Waves as Detected by Time and Frequency-Based Methods. Acta Neurochir Suppl. May 2016; 122:233-8.
5.Budohoski et al. Monitoring Cerebral Autoregulation After Subarachnoid Hemorrhage. Acta Neurochir Suppl. May 2016; 122:199-203.
6.Rhee et al. The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants. Acta Neurochir Suppl. May 2016; 122:151-5.
7.Rhee et al. The Diastolic Closing Margin Is Associated with Intraventricular Hemorrhage in Premature Infants. Acta Neurochir Suppl. May 2016; 122:147-50.
8.Rhee et al. Elevated Diastolic Closing Margin Is Associated with Intraventricular Hemorrhage in Premature Infants. Journal of Pediatrics. Apr 2016; doi: 10.1016/j.jpeds.2016.03.066. [Epub ahead of print]
9.Cardim et al. Prospective Study on Non-invasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods. Journal of Neurotrauma. Apr 2016; 33(8):792-802.
10.Donnelly et al. Cerebral Haemodynamics during Experimental Intracranial Hypertension. Journal of Cerebral Blood Flow & Metabolism. Mar 2016; pii: 0271678X16639060. [Epub ahead of print]
11.Rhee et al. Ontogeny of Cerebrovascular Critical Closing Pressure. Pediatric Research. Jul 2015; 78(1):71-5.
12.Phang et al. Expansion Duroplasty improves Intraspinal Pressure, Spinal Cord Perfusion Pressure and Vascular Pressure Reactivity Index in Patients with Traumatic Spinal Cord Injury. Journal of Neurotrauma. Jun 2015; 32(12):865-74.
13.Liu et al. Comparison of Frequency and Time Domain Methods of Assessment of Cerebral Autoregulation in Traumatic Brain Injury. Journal of Cerebral Blood Flow & Metabolism. Feb 2015; 35(2):248-56.
14.Donnelly et al. Increased Blood Glucose is related to Disturbed Cerebrovascular Pressure Reactivity after Traumatic Brain Injury. Neurocritical Care. Feb 2015; 22(1):20-5.
15.Budohoski et al. Bilateral Failure of Cerebral Autoregulation is related to Unfavorable Outcome after Subarachnoid Hemorrhage. Neurocritical Care. Feb 2015; 22(1):65-73.
16.Rhee et al. The Ontogeny of Cerebrovascular Pressure Autoregulation in Premature Infants. Journal of Perinatology. Dec 2014; 34(12):926-31.
17.Nasr et al. Baroreflex and Cerebral Autoregulation are Inversely Correlated. Circulation Journal. Sep 2014; 78(10):2460-7.
18.Swallow et al. Repeatability of Cerebrospinal Fluid Constant Rate Infusion Study. Acta Neurologica Scandinavica. Aug 2014; 130(2):131-8.
19.Dias et al. Pressures, Flow, and Brain Oxygenation during Plateau Waves of Intracranial Pressure. Neurocritical Care. Aug 2014; 21(1):124-32.
20.Werndle et al. Monitoring of Spinal Cord Perfusion Pressure in Acute Spinal Cord Injury: Initial Findings of the Injured Spinal Cord Pressure Evaluation Study. Critical Care Medicine. Mar 2014; 42(3):646-55.
21.Budohoski et al. Cerebral Autoregulation after Subarachnoid Haemorrhage: Comparison of Three Methods. Journal of Cerebral Blood Flow & Metabolism. Mar 2013; 33(3):449-56.