title: Hypocarbia and adverse outcome in neonatal hypoxic-ischemic encephalopathy.
abstract: OBJECTIVE
  To evaluate the association between early hypocarbia and 18- to 22-month outcome among neonates with hypoxic-ischemic encephalopathy.
  
  
  METHODS
  Data from the National Institute of Child Health and Human Development Neonatal Research Network randomized, controlled trial of whole-body hypothermia for neonatal hypoxic-ischemic encephalopathy were used for this secondary observational study. Infants (n = 204) had multiple blood gases recorded from birth to 12 hours of study intervention (hypothermia versus intensive care alone). The relationship between hypocarbia and outcome (death/disability at 18 to 22 months) was evaluated by unadjusted and adjusted analyses examining minimum PCO(2) and cumulative exposure to PCO(2) <35 mm Hg. The relationship between cumulative PCO(2) <35 mm Hg (calculated as the difference between 35 mm Hg and the sampled PCO(2) multiplied by the duration of time spent <35 mm Hg) and outcome was evaluated by level of exposure (none-high) using a multiple logistic regression analysis with adjustments for pH, level of encephalopathy, treatment group (± hypothermia), and time to spontaneous respiration and ventilator days; results were expressed as odds ratios and 95% confidence intervals. Alternative models of CO(2) concentration were explored to account for fluctuations in CO(2).
  
  
  RESULTS
  Both minimum PCO(2) and cumulative PCO(2) <35 mm Hg were associated with poor outcome (P < .05). Moreover, death/disability increased with greater cumulative exposure to PCO(2) <35 mm Hg.
  
  
  CONCLUSIONS
  Hypocarbia is associated with poor outcome after hypoxic-ischemic encephalopathy.
authors.affiliation: Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI 48201, USA. apappas@med.wayne.edu
authors.forename: Athina
authors.initials: A
authors.lastname: Pappas
authors.forename: Seetha
authors.initials: S
authors.lastname: Shankaran
authors.forename: Abbot R
authors.initials: AR
authors.lastname: Laptook
authors.forename: John C
authors.initials: JC
authors.lastname: Langer
authors.forename: Rebecca
authors.initials: R
authors.lastname: Bara
authors.forename: Richard A
authors.initials: RA
authors.lastname: Ehrenkranz
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Goldberg
authors.forename: Abhik
authors.initials: A
authors.lastname: Das
authors.forename: Rosemary D
authors.initials: RD
authors.lastname: Higgins
authors.forename: Jon E
authors.initials: JE
authors.lastname: Tyson
authors.forename: Michele C
authors.initials: MC
authors.lastname: Walsh
mesh_terms: D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D016857:Hypocapnia / Q000209:etiology* / Q000401:mortality / Q000628:therapy; D007036:Hypothermia, Induced / Q000379:methods*; D020925:Hypoxia-Ischemia, Brain / Q000150:complications* / Q000401:mortality / Q000628:therapy; D007231:Infant, Newborn; D008297:Male; D015996:Survival Rate; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology
chemical_list: D002245:Carbon Dioxide