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Erschienen in:
01.06.2006 | Brief Report
Continuous cardiac output monitoring after cardiopulmonary bypass: a comparison with bolus thermodilution measurement
Erschienen in: Intensive Care Medicine | Ausgabe 6/2006
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Objective
The interchangeability of continuous measurement of
cardiac output (CO) with the traditional bolus method in patients after
cardiopulmonary bypass (CPB) is uncertain.
Design
Prospective observational clinical study.
Setting
A 20-bed surgical ICU at a university
hospital.
Patients
Fourteen deeply sedated, ventilated, post-cardiac surgery
patients, all equipped with a pulmonary artery catheter.
Interventions
Six hours after the end of the CPB, 56 simultaneous
bolus and continuous measurements were compared by a linear regression
analysis and Bland–Altman analysis. Bolus CO was estimated by averaging
triplicate injections of 10 ml room-temperature NaCl 0.9%, delivered
randomly during the respiratory cycle. A stringent maximum difference of
0.55 l min—1 (about 10% of the mean bolus measured) was considered
as a clinically acceptable agreement between the two types of measurements.
To be interchangeable the limits of agreement (± 2 SD of the mean
difference between the two methods) should not exceed the chosen acceptable
difference.
Measurements and results
Continuous was correlated with bolus CO,
with a correlation coefficient of r2 = 0.68. (p< 0.01). The Bland–Altman
analysis demonstrated an objective mean bias of 0.33 ± 0.6 l min–1
(confidence interval of –0.87 – 1.58) with 34% of measured values
falling outside of the clinically acceptable limits.
Conclusion
Our results suggest that, in the first 6 h after CPB,
continuous and bolus CO determinations are not interchangeable; one third of
the values obtained by continuous CO fell outside the strict limits of
clinically useful precision.