Relationship between cardiac output, heart rate and microcirculation in patients with multiorgan dysfunction syndrome

Background: Multiple organ dysfunction syndrome (MODS) is one of the main causes of death in intensive care units. There is evidence that microcirculation in sepsis and coronary shock is regulated separately from hemodynamics. This study investigates the relationship between heart rate (HR), cardiac output (CO) and microcirculation in patients with MODS.Methods: This is a partial analysis of the "MODIFY study" (Reducing Elevated Heart Rate in Patients With Multiple Organ Dysfunction Syndrome [MODS] by Ivabradine). During the period 05/2010-09/2011, the microcirculation of 46 patients with septic and coronary MODS was measured using the sidestream dark field technique on the day of inclusion and 96 h later. Patients were randomized into a control and ivabradine treatment group.Results: Overall, there is a relevant improvement in microcirculation over time small perfused vessels, SPV [%] on day 0, d0:56.5 +/- 34.2/d4:73.2 +/- 22.1 (p = 0.03); perfused vessel density, PVDsmall [1/mm2] d0:7.5 +/- 5.0/d4:9.8 +/- 3.4 (p = 0.04); proportion of perfused vessels, PPVsmall [%] d0:51.6 +/- 31.6/d4:66.7 +/- 21.8 (p = 0.04); microcirculatory flow index, MFI d0:1.7 +/- 1.0/d4:2.2 +/- 0.7 (p = 0.05). Administration of ivabradine shows no effect. In patients with coronary MODS, there is a relevant correlation between microcirculatory parameters and cardiac output (SPV [%]: r = 0.98, p = 0.004). Patients with coronary MODS show better microcirculation values at high heart rates (> 100 bpm), while patients with septic MODS show an opposite relationship.Conclusion: The results indicate that in critically ill patients, depending on the genesis of the MODS, there are different relationships between HF or CO values, on the one hand, and the parameters of the microcirculation, on the other.