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Cardiac output measurement using the transesophageal Doppler method is less accurate than the thermodilution method

Toshiyuki Sawai1, Toshihiro Nohmi, Yoshihiko Ohnishi

  • 1Department of Anesthesiology, Osaka Medical College, Takatsuki, Japan; Department of Anesthesia, National Cardiovascular Center, Suita, Japan.

Anesthesia and Analgesia
|November 23, 2005
PubMed

Insights

Transesophageal Doppler and thermodilution methods for cardiac output (CO) measurement show agreement at 30 mmHg PaCO2. Thermodilution yields higher CO values at 40 mmHg PaCO2, impacting clinical accuracy.

Area of Science:

  • Cardiovascular Physiology
  • Anesthesiology
  • Surgical Monitoring

Background:

  • Cardiac output (CO) is a critical hemodynamic parameter.
  • Transesophageal Doppler (TED) and thermodilution are common CO monitoring techniques.
  • Partial arterial carbon dioxide (PaCO2) influences cerebral blood flow and potentially CO.

Purpose of the Study:

  • To compare CO measurements by TED and thermodilution at different PaCO2 levels.
  • To evaluate the impact of PaCO2 variations on the agreement between TED and thermodilution CO monitoring.

Main Methods:

  • 30 patients undergoing off-pump coronary artery bypass graft surgery were studied.
  • CO was measured using TED and thermodilution.
  • PaCO2 was maintained at 30 mmHg and 40 mmHg in random order.

Main Results:

  • Thermodilution showed significantly higher CO at 40 mmHg PaCO2 (4.17 L/min) vs. 30 mmHg PaCO2 (3.78 L/min).
  • TED showed no significant difference in CO between 30 mmHg (3.77 L/min) and 40 mmHg PaCO2 (3.85 L/min).
  • Bland-Altman analysis indicated agreement at 30 mmHg PaCO2 but a bias at 40 mmHg PaCO2.

Conclusions:

  • TED and thermodilution methods for CO determination agree at 30 mmHg PaCO2.
  • Thermodilution CO measurements are higher than TED at 40 mmHg PaCO2.
  • PaCO2 levels can affect the agreement between these CO monitoring techniques.

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