title: Early end-tidal carbon monoxide levels, patency of the ductus arteriosus and regional cerebral oxygenation in preterm infants.
abstract: BACKGROUND
  Carbon monoxide (CO), a relaxant regulator of muscle tone and marker of oxidative stress and inflammation, can be measured in exhaled air by determination of end-tidal CO corrected for CO in ambient air (ETCOc).
  
  
  OBJECTIVE
  Increased endogenous production of CO may influence patency of the ductus arteriosus, cerebral perfusion and, subsequently, cerebral oxygenation. The aim was to study the relation between early ETCOc levels, hemodynamically significant patent ductus arteriosus (hsPDA) and cerebral oxygenation (rScO2) in preterm infants <32 weeks' gestational age and determine predictive values of ETCOc for hsPDA.
  
  
  METHODS
  ETCOc was measured in 91 infants within the first 24 h after birth. A hsPDA was diagnosed according to echocardiographic indices. In 78/91 infants, rScO2 was monitored with near-infrared spectroscopy to assess cerebral oxygenation.
  
  
  RESULTS
  ETCOc values were significantly higher in infants who subsequently developed hsPDA (2.3 ± 0.7 ppm) vs. no-hsPDA (1.7 ± 0.6 ppm), p < 0.001. With a cut-off value of 2.5 ppm, positive and negative predictive values of ETCOc for hsPDA were 55 and 88%, respectively. rScO2 values were not different between the two groups (64 ± 1 vs. 65 ± 3%, NS).
  
  
  CONCLUSIONS
  The higher ETCOc values in hsPDA infants early after birth reflect the early relaxant state of ductal muscular tone. ETCOc <2.5 ppm within 24 h after birth may predict the subsequent absence of hsPDA. ETCOc showed no correlation with cerebral oxygenation in both groups.
authors.affiliation: Department of Neonatology, Wilhelmina Children's Hospital/University Medical Center Utrecht, The Netherlands.
authors.forename: Laura M L
authors.initials: LM
authors.lastname: Dix
authors.forename: Cornelie A
authors.initials: CA
authors.lastname: Blok
authors.forename: Petra M A
authors.initials: PM
authors.lastname: Lemmers
authors.forename: Niek
authors.initials: N
authors.lastname: van der Aa
authors.forename: Mirella C
authors.initials: MC
authors.lastname: Molenschot
authors.forename: Hendrik J
authors.initials: HJ
authors.lastname: Vreman
authors.forename: Tannette
authors.initials: T
authors.lastname: Krediet
authors.forename: Frank
authors.initials: F
authors.lastname: van Bel
mesh_terms: D001944:Breath Tests; D002245:Carbon Dioxide / Q000378:metabolism*; D002560:Cerebrovascular Circulation; D004374:Ductus Arteriosus, Patent / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D045853:Exhalation; D005865:Gestational Age; D006439:Hemodynamics; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008168:Lung / Q000378:metabolism* / Q000503:physiopathology; D010092:Oximetry / Q000379:methods; D010100:Oxygen / Q000097:blood*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D019265:Spectroscopy, Near-Infrared
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen