title: Evaluation of adjusted central venous blood gases versus arterial blood gases of patients in post-operative paediatric cardiac surgical intensive care unit.
abstract: OBJECTIVE
  Central venous catheters are in situ in most of the intensive care unit (ICU) patients, which may be an alternative for determining acid-base status and can reduce complications from prolonged arterial cannulation. The aim of this study was to examine the reliability between adjusted central venous blood gas (aVBG) and arterial blood gas (ABG) samples for pH, partial pressure of carbon-di-oxide (pCO2), bicarbonate (HCO3 (-)), base excess (BE) and lactates in paediatric cardiac surgical ICU.
  
  
  METHODS
  We applied blood gas adjustment rule, that is aVBG pH = venous blood gas (VBG) pH +0.05, aVBG CO2 = VBG pCO2 - 5 mm Hg from the prior studies. In this study, we validated this relationship with simultaneous arterial and central venous blood obtained from 30 patients with four blood sample pairs each in paediatric cardiac surgical ICU patients.
  
  
  RESULTS
  There was a strong correlation (R i.e., Pearson's correlation) between ABG and aVBG for pH = 0.9544, pCO2 = 0.8738, lactate = 0.9741, HCO3 (-) = 0.9650 and BE = 0.9778. Intraclass correlation co-efficients (ICCs) for agreement improved after applying the adjustment rule to venous pH (0.7505 to 0.9454) and pCO2 (0.4354 to 0.741). Bland Altman showed bias (and limits of agreement) for pH: 0.008 (-0.04 to + 0.057), pCO2: -3.52 (-9.68 to +2.65), lactate: -0.10 (-0.51 to +0.30), HCO3 (-): -2.3 (-5.11 to +0.50) and BE: -0.80 (-3.09 to +1.49).
  
  
  CONCLUSIONS
  ABG and aVBG samples showed strong correlation, acceptable mean differences and improved agreement (high ICC) after adjusting the VBG. Hence, it can be promising to use trend values of VBG instead of ABG in conjunction with a correction factor under stable haemodynamic conditions.
authors.affiliation: Department of Cardiac Anaesthesiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, India.
authors.forename: Naveen G
authors.initials: NG
authors.lastname: Singh
authors.affiliation: Department of Cardiac Anaesthesiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, India.
authors.forename: S R
authors.initials: SR
authors.lastname: Prasad
authors.affiliation: Department of Cardiac Anaesthesiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, India.
authors.forename: V
authors.initials: V
authors.lastname: Manjunath
authors.affiliation: Department of Cardiac Anaesthesiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, India.
authors.forename: P S
authors.initials: PS
authors.lastname: Nagaraja
authors.affiliation: Department of Cardiac Anaesthesiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, India.
authors.forename: Pranav J
authors.initials: PJ
authors.lastname: Adoni
authors.affiliation: Department of Cardiac Anaesthesiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, India.
authors.forename: Divya
authors.initials: D
authors.lastname: Gopal
authors.affiliation: Department of Cardiac Anaesthesiology, Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, Karnataka, India.
authors.forename: A M
authors.initials: AM
authors.lastname: Jagadeesh
keywords: Adjusted venous blood gas; arterial blood gas; venous blood gas