What effect of vasoactive drugs on passive leg raising response in critically ill patients?

Introduction

Passive leg raising (PLR) mimics the hemodynamic effects of rapid fluid loading (FL) by shifting venous blood from the legs towards the intrathoracic compartment and by increasing right and left ventricular preloads.

Aim

To test the effect of vasoactive drugs on PLR response.

Patients and methods

During a period of 2 months (September–November 2004) were enrolled all patients with sepsis or septic shock under mechanical ventilation who needed FL. The hemodynamic measures include heart rate, invasive arterial pressure, pulse pressure (PP), venous central pressure in a supine position and after leg raising (45°); before and immediately after FL of 300 ml saline solution.

Results

Twenty-eight hemodynamics measures were made. All patients were mechanically ventilated and deeply sedated. Age 55 ± 18 years, SAPS II 37 ± 17. The patients were divided into two groups.

Group 1 (with vasoactive drug): nine measures, age 58 ± 15 years, SAPS II 48 ± 26. The increase of PP after PLR is 4 ± 2.7 mmHg, while the increase of PP after FL is 5 ± 3 mmHg.

Group 2 (without vasoactive drug): 19 measures, age 54 ± 19 years, SAPS II 33 ± 10. The increase of arterial PP after PLR is 10 ± 8 mmHg while the increase of PP after FL is 8.3 ± 7 mmHg.

Discussion

PLR predicts the effect of FL in all patients. It depends in part on the volume of blood contained in the leg vessels. The PP increase after PLR is more important in patients without vasoactive drugs (10 ± 8 vs 4 ± 2.7 mmHg).

Conclusion

PLR is a very simple technique to predict the effect of FL. Its effects seem to be less important in patients with vasoactive drugs.