title: Noninvasive Cardiac Output Estimation by Inert Gas Rebreathing in Mechanically Ventilated Pediatric Patients.
abstract: To assess the feasibility and accuracy of inert gas rebreathing (IGR) pulmonary blood flow (Qp) estimation in mechanically ventilated pediatric patients, potentially providing real-time noninvasive estimates of cardiac output.
  
  
  
  In mechanically ventilated patients in the pediatric catheterization laboratory, we compared IGR Qp with Qp estimates based upon the Fick equation using measured oxygen consumption (VO2) (FickTrue); for context, we compared FickTrue with a standard clinical short-cut, replacing measured with assumed VO2 in the Fick equation (FickLaFarge, FickLundell, FickSeckeler). IGR Qp and breath-by-breath VO2 were measured using the Innocor device. Sampled pulmonary arterial and venous saturations and hemoglobin concentration were used for Fick calculations. Qp estimates were compared using Bland-Altman agreement and Spearman correlation.
  
  
  
  The final analysis included 18 patients aged 4-23 years with weight >15 kg. Compared with the reference FickTrue, IGR Qp estimates correlated best and had the least systematic bias and narrowest 95% limits of agreement (results presented as mean bias ±95% limits of agreement): IGR -0.2 ± 1.1 L/min, r = 0.90; FickLaFarge +0.7 ± 2.2 L/min, r = 0.80; FickLundell +1.6 ± 2.9 L/min, r = 0.83; FickSeckeler +0.8 ± 2.5 L/min, r = 0.83.
  
  
  
  IGR estimation of Qp is feasible in mechanically ventilated patients weighing >15 kg, and agreement with FickTrue Qp estimates is better for IGR than for other Fick Qp estimates commonly used in pediatric catheterization. IGR is an attractive option for bedside monitoring of Qp in mechanically ventilated children.
authors: Department of Cardiology, Boston Children's Hospital, Boston, MA.
authors: Amanda M
authors: AM
authors: Perak
authors: Department of Cardiology, Boston Children's Hospital, Boston, MA; Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA.
authors: Alexander R
authors: AR
authors: Opotowsky
authors: Division of Critical Care, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA.
authors: Brian K
authors: BK
authors: Walsh
authors: Department of Cardiology, Boston Children's Hospital, Boston, MA.
authors: Jesse J
authors: JJ
authors: Esch
authors: Division of Cardiac Anesthesia, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA.
authors: James A
authors: JA
authors: DiNardo
authors: Division of Cardiac Anesthesia, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, MA.
authors: Barry D
authors: BD
authors: Kussman
authors: Department of Cardiology, Boston Children's Hospital, Boston, MA.
authors: Diego
authors: D
authors: Porras
authors: Department of Cardiology, Boston Children's Hospital, Boston, MA. Electronic address: Jonathan.Rhodes@cardio.chboston.org.
authors: Jonathan
authors: J
authors: Rhodes
mesh_terms: D000293:Adolescent; D001944:Breath Tests; D002302:Cardiac Output; D002648:Child; D002675:Child, Preschool; D005260:Female; D006334:Heart Function Tests / Q000379:methods*; D006801:Humans; D008297:Male; D005741:Noble Gases / Q000008:administration & dosage; D010101:Oxygen Consumption; D012119:Respiration; D012121:Respiration, Artificial; D055815:Young Adult
chemical_list: D005741:Noble Gases
keywords: cardiac output; cardiology; critical care; oxygen consumption