Comparison between cardiac output values measured by thermodilution and partial carbon dioxide rebreathing in patients with acute lung injury

Abstract

RESULTS:There was a poor positive correlation between the methods studied for the patients from groups A (r = 0.52, p < 0.001) and B (r = 0.47, p < 0.001). The application of the Bland-Altman test made it possible to expose the lack of agreement between the methods (group A: -0.9 ± 2.71 l/min; 95% CI = -1.14 to -0.48; and group B: -1.75 ± 2.05 l/min; 95% CI = -2.11 to -1.4). The comparison of the results (Student t and Mann-Whitney tests) within each group and between the groups showed significant difference (p = 0.000, p < 0.05). DISCUSSION:Errors in estimating CaCO 2 (arterial CO 2 content) from ETCO 2 (end-tidal CO 2 ) and situations of hyperdynamic circulation associated with dead space and/or increased shunt possibly explain our results. CONCLUSION:Under the conditions of this study, the results obtained allow us to conclude that, in patients with acute lung injury, the cardiac output determined by partial rebreathing of CO 2 differs from the measurements obtained by thermodilution. This difference becomes greater, the more critical the lung injury is.

Perioperative Cardiac Output Monitoring Utilizing Non-pulse Contour Methods

“…This technique was found to have good agreement with PAC thermodilution in animal models [21], surgical/ICU (intensive care unit) patients [22,23], pediatric Fig. 1 Benefits and risks associated with CO monitoring devices patients [24], and cardiac surgery patients [25]; moderate agreement in thoracic surgery patients [26] and cardiac surgery patients [27]; and poor agreement in post-cardiac surgery patients [28,29] and acute lung injury patients [30]. The device appears to have a high repeatability (4%) [28,31].…”

“…The drawbacks of this technique are the need for stable CO 2 elimination, which prevents its use in awake, spontaneously breathing subjects, and its unreliability in patients with chest trauma or pulmonary pathology, [28,30,32,33]. Because CO 2 detection is crucial in this technique, ventilator setting is an important factor in ensuring the accuracy of measurements.…”

The effects of patient positioning on hemodynamic parameters

“…The SV decrease or the change caused by hypovolemia may induce bigger change in ETCO 2 . Second, ETCO 2 monitoring are available in lung parenchyma without lesions because acute lung injury can lead to decreased ETCO 2 that failed to reflect SV [19]. Third, deep respiration can make increases in ETCO 2 .…”

Contemporary perioperative haemodynamic monitoring

“…Many studies suggest moderate to good agreement with CO measurements obtained by the thermodilution method during surgery and in ICU mechanically ventilated patients [84][85][86][87], but there was a great bias during a period of rapidly changing shunt and dead space, as occurs at the start of one-lung ventilation [88]. Although many studies have shown that CO was underestimated by the partial CO 2 rebreathing method compared with the thermodilution method, it still can be used to guide haemodynamic management during surgery [87,89]. In patients with acute lung injury, CO derived from the partial CO 2 rebreathing method was shown to be unreliable [90].…”