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Updated: Jul 11, 2026
Expired CO2 Measurement in Intubated or Spontaneously Breathing Patients from the Emergency Department
Published on: January 29, 2011
Evaluation of partial carbon dioxide rebreathing cardiac output measurement during thoracic surgery
Ju-Mei Ng1, Mark Y Chow, Pierre C Ip-Yam
1Department of Anaesthesia and Surgical Intensive Care, Singapore General Hospital, Singapore. jng1@partners.org
Objective:
Noninvasive partial CO2 rebreathing (NICO; Novametrix Medical Systems, Inc, Wallingford, CT) is a relatively new alternative to thermodilution (TDCO) for measurement of cardiac output. This study compares the 2 methods during thoracic surgery and one-lung ventilation.
Design:
A prospective, observational study.
Setting:
A tertiary hospital.
Participants:
Twelve adult patients undergoing elective thoracotomy and one-lung ventilation in the lateral decubitus position.
Interventions:
Paired measurements of cardiac output were performed during (1) 2-lung ventilation in the supine position (postinduction of anesthesia), (2) 10 minutes after initiation of one-lung ventilation in the lateral decubitus position with the nondependent chest open, and (3) after 30 minutes on one-lung ventilation. An average of 3 consecutive (10 mL 20 degrees C saline) TDCO measurements made during end-expiration was compared with corresponding NICO measurements.
Measurements And Main Results:
The NICO showed a tendency to underestimate cardiac output compared with TDCO at all measurement times. Overall, bias was -0.29 L/min and limits of agreement -1.69 to 1.43 L/min.
Conclusions:
There was a moderate agreement between cardiac output measurements obtained with the NICO and TDCO. The present data suggest that the NICO technique may be useful during thoracic surgery.
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