- Poster presentation
- Open Access
PiCCO monitoring – are two injections enough?
© BioMed Central Ltd. 2007
- Published: 22 March 2007
- Mechanical Ventilation
- Septic Shock
- Emergency Medicine
- Saline Solution
PiCCO monitoring using the thermodilution technique has become an alternative method of invasive haemodynamic monitoring for the critically ill patient. Usually the results of an arbitrarily chosen number (one to five) of thermal indicator injections are averaged to increase the reliability of the measurement. The number of injections needed to achieve a given level of precision has, however, not previously been systematically investigated. We tried in this study to validate the accuracy of two injections instead of three injections.
We analysed retrospectively all data (triplate measurements) obtained during the past 2 years by PiCCO monitoring: injection of 10 ml saline solution three times by the same operator. We compared the cardiac index (CI) obtained at each bolus, the average of the CI obtained at the first two injections (M1) and then the triplate (M2).
Two hundred and forty-nine triplates were collected in 25 patients with septic shock, under mechanical ventilation. There were no significant differences in CI at each bolus. The average of the first two iced injections M1 = 3.28 ± 1.07 l/min/m2. The average of the triplate M2 = 5.74 ± 1.07.
Normally, we consider that 10–15% of variation in the CI signifies a change in the haemodynamic state. The difference between M1 and M2 exceeds 15%. In the literature, Nilsson and colleagues  demonstrated concerning the pulmonary arterial catheter that we need an average of at least four injections to be 95% confident.
With PiCCO monitoring, certainly two injections are not enough to have reliable measurement of the CI.