Hemodynamic monitoring by double indicator dilution technique in patients after orthotopic heart transplantation

Background

Cardiac index (CI) and preload monitoring by pulmonary artery catheter (PAC) is increasingly confronted with criticism. We evaluated the less invasive arterial double indicator dilution method (TDD) as an alternative. Preload with this technique is determinated by measuring intrathoracic blood volume index (ITBVI) and global enddiastolic volume index (GEDVI) instead of filling pressures CVP and PCWP. As there is no clinical experience in patients with denervated hearts, we investigated this monitoring method in patients after heart transplantation.

Methods

Forty patients (34 male, 54.4 ± 8.5 years) were studied with the TDD and PAC methods. Measurements were performed at the ICU at 3, 6, 12, 24, 36, 48 and 72 h postoperatively. Based on Frank-Starling law, ITBVI, GEDVI, CVP, and PCWP have been investigated on their usefulness as preload indicators and for this purpose correlated with stroke volume index (SVI).

Results

No difference between femoral and pulmonary artery CI were found (r = 0.98, bias 0.35 l/min/m²). Changes of CVP (r = -0.23) and PCWP (r = -0.06) did not correlate significantly to changes in SVI. ITBVI (r = 0.55) and GEDVI (r = 0.63) showed significant correlations. Equally directed changes of SVI with GEDVI and ITBVI occurred in 70.3% and 66.9% respectively, of SVI with CVP and PCWP in 41.1% and 41.9%.

Conclusion

CVP and PCWP are not as reliable preload parameters as ITBVI and GEDVI. The latter even in denervated hearts show good correlations to SVI. They can be obtained less invasively and therefore should be the method of choice.