title: Defining hypotension in anesthetized infants by individual awake blood pressure values: a prospective observational study.
abstract: BACKGROUND
  Blood pressure (BP) is the most commonly applied clinical surrogate parameter for tissue perfusion and cerebral autoregulation. Hypotension during anesthesia may contribute to unfavorable outcome in young children. Hypotension in anesthetized infants can be defined using BP values relative to individual awake baseline or absolute BP values.
  
  
  OBJECTIVE
  The aim of this study was to investigate the applicability of the two definitions and to compare the incidences of hypotension.
  
  
  METHODS
  This was a prospective observational study in 151 infants <12 months of age. The percentage of successful awake BP measurements was calculated and related to the infant's behavioral state. Hypotension under sevoflurane anesthesia was defined by a decrease of mean arterial pressure (MAP) relative to awake baseline (>20% in infants <6 months, >40% in infants >6 months) or absolute MAP values (<35 mmHg in infants <6 months, <43 mmHg in infants >6 months). The incidences of hypotension using the two definitions were compared.
  
  
  RESULTS
  Awake BP values were obtained in 85% of the patients. Calm patients were more likely to allow their BP to be measured than anxious patients. Anxious patients had higher preinduction MAP values than calm patients. The relative BP approach resulted in a higher incidence of postinduction hypotension than using absolute BP values.
  
  
  CONCLUSIONS
  Awake BP values were unobtainable in 15% of our patients, resulting in the necessity to define hypotension under anesthesia using absolute BP values. Definitions of hypotension using either absolute MAP or values relative to awake baseline are not interchangeable.
authors.affiliation: Department of Anaesthesia, Sophia Children's Hospital, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Weber
authors.affiliation: Department of Anaesthesia, Sophia Children's Hospital, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Laurens
authors.initials: L
authors.lastname: Koning
authors.affiliation: Department of Anaesthesia, Sophia Children's Hospital, Erasmus University Medical Center, Rotterdam, The Netherlands.
authors.forename: Gail P
authors.initials: GP
authors.lastname: Scoones
mesh_terms: D018685:Anesthetics, Inhalation; D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000379:methods*; D005260:Female; D006801:Humans; D007022:Hypotension / Q000175:diagnosis*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008738:Methyl Ethers; D011446:Prospective Studies; D000077149:Sevoflurane
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane
keywords: blood pressure; cerebral autoregulation; cerebral oxygenation; general anesthesia; hypotension; infant