Reliability of cardiac output calculation by the fick principle and central venous oxygen saturation in emergency conditions.

BACKGROUND

For many years thermodilution has been the gold standard for determining cardiac output in the critically ill patients. Less invasive methods have recently been introduced. This study aimed at evaluating the agreement between cardiac output (CO) measured by a new Fick method, using central venous saturation (Scvo(2)), and that measured by the classic thermodilution technique, in patients requiring emergent CO evaluation.

SETTINGS

Prospective clinical study in a university-affiliated, tertiary hospital, at surgical and general intensive care units.

PATIENTS AND METHODS

Fifteen mechanically ventilated patients arriving in the emergency department in hemodynamic shock, had immediately a pulmonary artery catheter introduced under fluoroscopy upon arrival into the ICU. Cardiac output (CO) was obtained in each patient via both thermodilution and the Fick method, using oxygen consumption, SpO(2) and Scvo(2).

RESULTS

COs ranged between 2 and 2.3 (in the Fick and thermodilution methods, respectively) and 19 or 19.5 l/min (respectively). Mean thermodilution-derived CO was 6.2 +/- 4.2 l/min whereas the Fick's was 7.0 +/- 4.3 l/min. There was statistical significant correlation between the two modalities of measurements, with an r (2) = 0.9 (P < 0.001).

CONCLUSIONS

The new method of Fick assessed emergent CO as reliably as the thermodilution, regardless of whether it was low or high. The use of Scvo(2) allows for prompt bedside calculation for most emergency patients.