Performance of cardiac output measurement derived from arterial pressure waveform analysis in patients undergoing triple-H-therapy of cerebral vasospasms after subarachnoidal hemorrhage

Introduction

The validity of an arterial waveform-based device for measuring cardiac output (CO) without the need for invasive calibration (FloTrac/Vigileo) in patients needing large doses of vasoactive medication has not yet been thoroughly studied. We performed the present study to assess the validity of both the second-generation and the third-generation software compared with transpulmonary thermodilution CO measurement using the PiCCO technology in patients undergoing triple-H-therapy (hypertonia, hypervolemia, hemodilution) of cerebral vasospasms after subarachnoidal hemorrhage.

Methods

Twenty-three patients (18 females and five males) were included in this study. All of them were suffering from a subarachnoidal hemorrhage (Hunt&Hess grade I to V) due to rupture of a cerebral aneurysm. Triple-H-therapy was initiated for the treatment of cerebral vasospasm. Simultaneous CO measurements by bolus thermodilution and the FloTrac/Vigileo device were obtained at baseline as well as 2 hours, 6 hours, 12 hours, 24 hours, 48 hours and 72 hours after inclusion. A percentage error of 30% or less was established as the criterion for method interchangeability.

Results

Patients received vasoactive support with 0.53 ± 0.46 μg/kg/minute norepinephrine, resulting in a mean arterial pressure of 104 ± 13.6 mmHg and a systemic vascular resistance index of 1,741.17 ± 432.50 dyn·s/cm⁵/m². One hundred and fifty-one CO-data pairs were analyzed. Transpulmonary thermodilution CO ranged from 5.18 to 14.28 l/minute (mean 8.61 ± 1.93 l/minute) and FloTrac/Vigileo CO ranged from 4.1 to 13.7 l/minute (mean 7.62 ± 1.79 l/minute). Bias and precision (1.96SD of the bias) were 0.99 l/minute and 2.46 l/minute, resulting in an overall percentage error of 28.55%. Subgroup analysis revealed a percentage error of 29.53% for 67 data pairs measured using the second-generation FloTrac software and 26.44% for 84 data pairs analyzed by the third-generation software.

Conclusions

In patients undergoing triple-H-therapy and needing extensive vasoactive support, CO values obtained by arterial waveform analysis showed good agreement with intermittent transpulmonary thermodilution CO measurements, which was improved by the introduction of a new software generation.