Zachary Darby
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Zachary Darby has a total of 14 co-authors. Here are the top co-authors by number of shared publications:
- Etchill Eric
Dept. of Surgery, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, US, USA
1 shared publication - Glenn J. R. Whitman
Division of Cardiac Surgery, Department of Surgery Johns Hopkins Hospital Baltimore Maryland USA
1 shared publication - Ifeanyi Chinedozi
Dept. of Cardiac Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, US, USA
1 shared publication - Janaka Senarathna
The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, USA
1 shared publication - Jessica Briscoe
Dept. of Cardiac Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, US, USA
1 shared publication - Jin Kook Kang
Johns Hopkins University School of Medicine
1 shared publication
Latest Publications
- Open Access
- 19 August 2025
- Published by MDPI AG in Preprints.org
Proof-of-Concept Monitoring of Cerebral Hemodynamics in a Porcine Extracorporeal Cardiopulmonary Resuscitation Model Using Dual-Mode Laser Speckle and Intrinsic Optical Imaging
Extracorporeal cardiopulmonary resuscitation (ECPR) is increasingly used for refractory cardiac arrest, yet neurologic outcome is often limited by acute brain injury (ABI) secondary to disrupted cerebrovascular autoregulation (CVAR). We established a proof-of-concept porcine model that combines veno-arterial ECMO with dual-mode optical neuromonitoring. After 10 minutes of untreated ventricular fibrillation, ECMO support was initiated, and a cranial window enabled real-time laser speckle contrast imaging (LSCI) of cerebral blood flow (CBF) and intrinsic optical signal (IOS) mapping of cerebral blood volume (CBV). Mean arterial pressure (MAP) was recorded continuously, and vessel-specific hemoglobin-volume index (HVx) was calculated to quantify CVAR. Cortical vessels became pressure-passive—HVx \texorpdfstring{$\geq$}{>=} 0.3, indicating loss of autoregulation—during the initial minutes of reperfusion and again when ECMO pump speed was deliberately reduced to 75\% and 50\% of baseline. The impairment was heterogeneous and reversible, with adjacent vessels showing either intact (HVx \texorpdfstring{$\leq$}{< =} 0) or impaired CVAR in the same epoch. Neither pump flow nor systemic MAP reliably mirrored these microvascular changes: at several time points, CBF rose while pump output and MAP fell, and vice versa. Despite technical challenges (motion artifact, coagulopathy, lack of invasive flow validation), this single-subject study demonstrates the feasibility of simultaneous LSCI and IOS during ECPR.
- 19 August 2025
- Published by MDPI AG in Preprints.org
Open AccessProof-of-Concept Monitoring of Cerebral Hemodynamics in a Porcine Extracorporeal Cardiopulmonary Resuscitation Model Using Dual-Mode Laser Speckle and Intrinsic Optical Imaging
Extracorporeal cardiopulmonary resuscitation (ECPR) is increasingly used for refractory cardiac arrest, yet neurologic outcome is often limited by acute brain injury (ABI) secondary to disrupted cerebrovascular autoregulation (CVAR). We established a proof-of-concept porcine model that combines veno-arterial ECMO with dual-mode optical neuromonitoring. After 10 minutes of untreated ventricular fibrillation, ECMO support was initiated, and a cranial window enabled real-time laser speckle contrast imaging (LSCI) of cerebral blood flow (CBF) and intrinsic optical signal (IOS) mapping of cerebral blood volume (CBV). Mean arterial pressure (MAP) was recorded continuously, and vessel-specific hemoglobin-volume index (HVx) was calculated to quantify CVAR. Cortical vessels became pressure-passive—HVx \texorpdfstring{$\geq$}{>=} 0.3, indicating loss of autoregulation—during the initial minutes of reperfusion and again when ECMO pump speed was deliberately reduced to 75\% and 50\% of baseline. The impairment was heterogeneous and reversible, with adjacent vessels showing either intact (HVx \texorpdfstring{$\leq$}{< =} 0) or impaired CVAR in the same epoch. Neither pump flow nor systemic MAP reliably mirrored these microvascular changes: at several time points, CBF rose while pump output and MAP fell, and vice versa. Despite technical challenges (motion artifact, coagulopathy, lack of invasive flow validation), this single-subject study demonstrates the feasibility of simultaneous LSCI and IOS during ECPR.