title: Current definitions of hypotension do not predict abnormal cranial ultrasound findings in preterm infants.
abstract: OBJECTIVE
  Hypotension is a commonly treated complication of prematurity, although definitions and management guidelines vary widely. Our goal was to examine the relationship between current definitions of hypotension and early abnormal cranial ultrasound findings.
  
  
  METHODS
  We prospectively measured mean arterial pressure in 84 infants who were < or = 30 weeks' gestational age and had umbilical arterial catheters in the first 3 days of life. Sequential 5-minute epochs of continuous mean arterial pressure recordings were assigned a mean value and a coefficient of variation. We applied to our data 3 definitions of hypotension in current clinical use and derived a hypotensive index for each definition. We examined the association between these definitions of hypotension and abnormal cranial ultrasound findings between days 5 and 10. In addition, we evaluated the effect of illness severity (Score for Neonatal Acute Physiology II) on cranial ultrasound findings.
  
  
  RESULTS
  Acquired lesions as shown on cranial ultrasound, present in 34 (40%) infants, were not predicted by any of the standard definitions of hypotension or by mean arterial pressure variability. With hypotension defined as mean arterial pressure < 10th percentile (< 33 mmHg) for our overall cohort, mean value for mean arterial pressure and hypotensive index predicted abnormal ultrasound findings but only in infants who were > or = 27 weeks' gestational age and those with lower illness severity scores.
  
  
  CONCLUSIONS
  Hypotension as diagnosed by currently applied thresholds for preterm infants is not associated with brain injury on early cranial ultrasounds. Blood pressure management directed at these population-based thresholds alone may not prevent brain injury in this vulnerable population.
authors.affiliation: Department of Neurology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Limperopoulos
authors.forename: Haim
authors.initials: H
authors.lastname: Bassan
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Kalish
authors.forename: Steven A
authors.initials: SA
authors.lastname: Ringer
authors.forename: Eric C
authors.initials: EC
authors.lastname: Eichenwald
authors.forename: Gene
authors.initials: G
authors.lastname: Walter
authors.forename: Marianne
authors.initials: M
authors.lastname: Moore
authors.forename: Matthew
authors.initials: M
authors.lastname: Vanasse
authors.forename: Donald N
authors.initials: DN
authors.lastname: DiSalvo
authors.forename: Janet S
authors.initials: JS
authors.lastname: Soul
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Volpe
authors.forename: Adré J
authors.initials: AJ
authors.lastname: du Plessis
mesh_terms: D001794:Blood Pressure / Q000502:physiology; D001930:Brain Injuries / Q000000981:diagnostic imaging / Q000209:etiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007022:Hypotension / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging*; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012886:Skull / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D014463:Ultrasonography