Effects of insertion depth and use of the sidearm of the introducer sheath of pulmonary artery catheters in cardiac output measurement.

OBJECTIVE

To investigate the effects of various insertion depths and sidearm functions of the introducer sheath of pulmonary artery flotation catheters on cardiac output measurement.

DESIGN

Prospective, randomized, crossover study.

SETTING

A general intensive care unit.

PATIENTS

Ten patients who had a pulmonary artery flotation catheter placed in the right internal jugular vein as part of their clinical management.

INTERVENTIONS

Cardiac output was measured at three insertion depths of the pulmonary artery catheter, each with a different rate of flow into the introducer sheath.

MEASUREMENTS AND MAIN RESULTS

Significant differences of up to 23% occurred in the measurement of cardiac output under the various conditions. Cardiac output measurement is greater, the closer the injection port lies to the introducer sheath and the more open the introducer sheath sidearm.

CONCLUSIONS

All users of pulmonary artery catheters should be alert to this problem. For reliable measurements of cardiac output by thermodilution, the cold saline injection port of the pulmonary artery catheter must be downstream of the introducer sheath, and the introducer sidearm must be closed.