title: Airway oximetry improves monitoring of dopamine effects in pediatric cardiac patients.
abstract: OBJECTIVE
  Simple, preferably noninvasive measurements of cardiac output are useful in pediatric patients receiving inotropic support. Oxygen saturation in pulmonary artery (Svo(2)) gives information about oxygen delivery and demand. Many inotropic drugs influence oxygen consumption. When effects on Svo(2) are studied, after a change in inotropic drug dosage, a change in oxygen consumption needs to be considered to accurately estimate the change in cardiac output. The aim of this investigation was to study whether information on inspired to end-tidal oxygen concentration difference (Fi-eto(2)) in addition to Svo(2) would improve estimation of changes in cardiac output.
  
  
  METHODS
  Prospective observational study of Fi-eto(2), Svo(2), and oxygen saturation from central vein (Scvco(2)) for measurements of circulatory and metabolic effects of changes in dopamine dosage.
  
  
  METHODS
  Intensive care unit in a children's hospital.
  
  
  METHODS
  Twenty patients (age 4 days to 98 months) were studied after cardiac surgery.
  
  
  METHODS
  Dopamine was administered in doses of 5, 10, 0, and 5 microg x kg(-1) x min(-1), 20 mins on each level.
  
  
  RESULTS
  Cardiac output, measured with thermodilution, oxygen saturation from systemic artery (Sao(2)), Svo(2), and Scvco(2) were measured at 15 mins on each dopamine dose. Oxygen consumption was calculated by using the Fick equation. Fi-eto(2) was measured continuously with a paramagnetic oxygen analyzer. Both cardiac output and oxygen consumption were affected by changes in dopamine dosage. Relative changes in cardiac output were poorly correlated to the change in 1/Sa-vo(2) (r(2) =.54). Using Fi-eto(2) improved correlation between changes in cardiac output and changes in Fi-eto(2)/Sa-vo(2) (r(2) =.72). When Svo(2) was replaced by Scvco(2), the correlation between changes in cardiac output and changes in Fi-eto(2)/Sa-cvco(2) was only slightly altered (r(2) =.69).
  
  
  CONCLUSIONS
  Dopamine affects oxygen consumption as well as cardiac output. The accuracy of Svo(2)-based estimations of changes in cardiac output after dopamine is enhanced if changes in Fi-eto(2) are also considered. The more easily achievable Scvco(2) gave equivalent information as Svo(2).
authors.affiliation: Department of Pediatric Anesthesia and Intensive Care, The Queen Silvia Children's Hospital, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Bengtsson
authors.forename: Karl Erik
authors.initials: KE
authors.lastname: Edberg
authors.forename: Stefan
authors.initials: S
authors.lastname: Hallhagen
authors.forename: Jan Peter
authors.initials: JP
authors.lastname: Bengtson