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Assessment of the relationship between cerebral and splanchnic oxygen saturations measured by near-infrared spectroscopy and direct measurements of systemic haemodynamic variables and oxygen transport after the Norwood procedure
  1. J Li,
  2. G S Van Arsdell,
  3. G Zhang,
  4. S Cai,
  5. T Humpl,
  6. C A Caldarone,
  7. H Holtby,
  8. A N Redington
  1. The Cardiac Program, The Hospital for Sick Children, Toronto, Ontario, Canada
  1. Correspondence to:
    Dr Andrew Redington
    Division of Cardiology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8; andrew.redington{at}sickkids.ca

Abstract

Objectives: To evaluate the clinical utility of near-infrared spectroscopic (NIRS) monitoring of cerebral (Sco2) and splanchnic (Sso2) oxygen saturations for estimation of systemic oxygen transport after the Norwood procedure.

Methods: Sco2 and Sso2 were measured with NIRS cerebral and thoracolumbar probes (in humans). Respiratory mass spectrometry was used to measure systemic oxygen consumption (V̇o2). Arterial (Sao2), superior vena caval (Svo2) and pulmonary venous oxygen saturations were measured at 2 to 4 h intervals to derive pulmonary (Qp) and systemic blood flow (Qs), systemic oxygen delivery (Do2) and oxygen extraction ratio (ERo2). Mixed linear regression was used to test correlations. A study of 7 pigs after cardiopulmonary bypass (study 1) was followed by a study of 11 children after the Norwood procedure (study 2).

Results:Study 1. Sco2 moderately correlated with Svo2, mean arterial pressure, Qs, Do2 and ERo2 (slope 0.30, 0.64. 2.30, 0.017 and −32.5, p < 0.0001) but not with Sao2, arterial oxygen pressure (Pao2), haemoglobin and V̇o2. Study 2. Sco2 correlated well with Svo2, Sao2, Pao2 and mean arterial pressure (slope 0.43, 0.61, 0.99 and 0.52, p < 0.0001) but not with haemoglobin (slope 0.24, p > 0.05). Sco2 correlated weakly with V̇o2 (slope −0.07, p  =  0.05) and moderately with Qs, Do2 and ERo2 (slope 3.2, 0.03, −33.2, p < 0.0001). Sso2 showed similar but weaker correlations.

Conclusions: Sco2 and Sso2 may reflect the influence of haemodynamic variables and oxygen transport after the Norwood procedure. However, the interpretation of NIRS data, in terms of both absolute values and trends, is difficult to rely on clinically.

  • Cao2, systemic arterial oxygen contents
  • CPB, cardiopulmonary bypass
  • Cpvo2, systemic pulmonary venous oxygen contents, Cvo2, systemic superior vena caval oxygen contents
  • Do2, systemic oxygen delivery
  • ERo2, oxygen extraction ratio
  • NIRS, near-infrared spectroscopy
  • Pao2, arterial oxygen pressure
  • Qp, pulmonary blood flow
  • Qs, systemic blood flow
  • Sao2, arterial oxygen saturation
  • Sco2, cerebral oxygen saturation
  • Sso2, splanchnic oxygen saturation
  • Svo2, superior vena caval oxygen saturation
  • o2, systemic oxygen consumption

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Footnotes

  • Published Online First 18 April 2006

  • This work was supported by the Heart and Stroke Foundation of Canada (JL and ANR), and the Canadian Institute of Health Research (JL, ANR, CC and GSV).

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