Diffuse Optical Monitoring of Cerebral Hemodynamics and Oxygen Metabolism during and after Cardiopulmonary Bypass: Hematocrit Correction and Neurological Vulnerability
Emilie J. Benson,
Danielle I. Aronowitz,
Rodrigo M. Forti,
Alec Lafontant,
Nicolina R. Ranieri,
Jonathan P. Starr,
Richard W. Melchior,
Alistair Lewis,
Jharna Jahnavi,
Jake Breimann,
Bohyun Yun,
Gerard H. Laurent,
Jennifer M. Lynch,
Brian R. White,
J. William Gaynor,
Daniel J. Licht,
Arjun G. Yodh,
Todd J. Kilbaugh,
Constantine D. Mavroudis,
Wesley B. Baker,
Tiffany S. Ko
Affiliations
Emilie J. Benson
Department of Physics & Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
Danielle I. Aronowitz
Division of Cardiothoracic Surgery, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Rodrigo M. Forti
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Alec Lafontant
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Nicolina R. Ranieri
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Jonathan P. Starr
Department of Anesthesiology and Critical Care Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Richard W. Melchior
Department of Perfusion Services, Cardiac Center, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Alistair Lewis
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
Jharna Jahnavi
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Jake Breimann
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Bohyun Yun
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Gerard H. Laurent
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Jennifer M. Lynch
Division of Cardiothoracic Anesthesiology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Brian R. White
Division of Cardiology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
J. William Gaynor
Division of Cardiothoracic Surgery, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Daniel J. Licht
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Arjun G. Yodh
Department of Physics & Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
Todd J. Kilbaugh
Department of Anesthesiology and Critical Care Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Constantine D. Mavroudis
Division of Cardiothoracic Surgery, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Wesley B. Baker
Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Tiffany S. Ko
Department of Anesthesiology and Critical Care Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
Cardiopulmonary bypass (CPB) provides cerebral oxygenation and blood flow (CBF) during neonatal congenital heart surgery, but the impacts of CPB on brain oxygen supply and metabolic demands are generally unknown. To elucidate this physiology, we used diffuse correlation spectroscopy and frequency-domain diffuse optical spectroscopy to continuously measure CBF, oxygen extraction fraction (OEF), and oxygen metabolism (CMRO2) in 27 neonatal swine before, during, and up to 24 h after CPB. Concurrently, we sampled cerebral microdialysis biomarkers of metabolic distress (lactate–pyruvate ratio) and injury (glycerol). We applied a novel theoretical approach to correct for hematocrit variation during optical quantification of CBF in vivo. Without correction, a mean (95% CI) +53% (42, 63) increase in hematocrit resulted in a physiologically improbable +58% (27, 90) increase in CMRO2 relative to baseline at CPB initiation; following correction, CMRO2 did not differ from baseline at this timepoint. After CPB initiation, OEF increased but CBF and CMRO2 decreased with CPB time; these temporal trends persisted for 0–8 h following CPB and coincided with a 48% (7, 90) elevation of glycerol. The temporal trends and glycerol elevation resolved by 8–24 h. The hematocrit correction improved quantification of cerebral physiologic trends that precede and coincide with neurological injury following CPB.
