title: Monitoring of Cerebrovascular Reactivity for Determination of Optimal Blood Pressure in Preterm Infants.
abstract: OBJECTIVE
  To define levels of mean arterial blood pressure (MABP) where cerebrovascular reactivity is strongest in preterm infants (ie, optimal MABP, or MABPOPT) and correlate deviations from MABPOPT with mortality and intraventricular hemorrhage (IVH).
  
  
  METHODS
  A total of 60 preterm infants born at median gestational age 26 ± 2 weeks (23 ± 2 to 32 ± 1) with indwelling arterial catheter were studied at a median 34 hours (range 5-228) of age. Tissue oxygenation heart rate (HR) reactivity index, which estimates cerebrovascular reactivity, was calculated as the moving correlation coefficient between slow waves of tissue oxygenation index, measured with near-infrared spectroscopy, and HR. MABPOPT was defined by dividing MABP into 2-mm Hg bins and averaging the tissue oxygenation HR reactivity index within those bins. A measurement of divergence from MABPOPT was calculated as the absolute difference between mean MABP and mean MABPOPT.
  
  
  RESULTS
  Individual MABPOPT was defined in 81% of the patients. A measurement of divergence from MABPOPT was greater in those patients who died (mean 4.2 mm Hg; 95% CI 3.33-4.96) compared with those who survived (mean 2.1 mm Hg; 95% CI 1.64-2.56), P = .013. Patients who had MABP lower than MABPOPT by 4 mm Hg or more had a greater rate of mortality (40%) than those with MABP close to or above MABPOPT (13%), P = .049. Patients with MABP greater than MABPOPT by 4 mm Hg had greater IVH scores, P = .042.
  
  
  CONCLUSIONS
  Continuous monitoring of cerebrovascular reactivity allows the determination of MABPOPT in preterm neonates. Significant deviation below MABPOPT was observed in infants who died. Deviation of MABP above optimal level was observed in infants who developed more severe IVH.
authors.affiliation: Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom. Electronic address: cs702@cam.ac.uk.
authors.forename: Cristine Sortica
authors.initials: CS
authors.lastname: da Costa
authors.affiliation: Department of Clinical Neurosciences, Academic Neurosurgical Unit, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom; Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Czosnyka
authors.affiliation: Department of Clinical Neurosciences, Academic Neurosurgical Unit, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Smielewski
authors.affiliation: Neonatal Unit, Elizabeth Garret Anderson Wing, University College London Hospital, London, United Kingdom.
authors.forename: Subhabrata
authors.initials: S
authors.lastname: Mitra
authors.affiliation: Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom.
authors.forename: Gordon N
authors.initials: GN
authors.lastname: Stevenson
authors.affiliation: Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom.
authors.forename: Topun
authors.initials: T
authors.lastname: Austin
mesh_terms: D001794:Blood Pressure; D002560:Cerebrovascular Circulation; D005260:Female; D005865:Gestational Age; D006339:Heart Rate; D017052:Hospital Mortality; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D008991:Monitoring, Physiologic; D010100:Oxygen / Q000378:metabolism*; D011446:Prospective Studies; D019265:Spectroscopy, Near-Infrared
chemical_list: D010100:Oxygen