Conventional hemodynamic resuscitation may fail to optimize tissue perfusion: an observational study on the effects of dobutamine, enoximone, and norepinephrine in patients with acute myocardial infarction complicated by cardiogenic shock

Abstract

Aim: To investigate the effects of inotropic agents on parameters of tissue perfusion in patients with cardiogenic shock.

Methods and results: Thirty patients with cardiogenic shock were included. Patients received dobutamine, enoximone, or norepinephrine. We performed hemodynamic measurements at baseline and after titration of the inotropic agent until cardiac index (CI) ≥ 2.5 L.min-1.m(-2) or mixed-venous oxygen saturation (SvO2) ≥ 70% (dobutamine or enoximone), and mean arterial pressure (MAP) ≥ 70 mmHg (norepinephrine). As parameters of tissue perfusion, we measured central-peripheral temperature gradient (delta-T) and sublingual perfused capillary density (PCD). All patients reached predefined therapeutic targets. The inotropes did not significantly change delta-T. Dobutamine did not change PCD. Enoximone increased PCD (9.1 [8.9-10.2] vs. 11.4 [8.4-13.9] mm.mm(-2); p<0.05), and norepinephrine tended to decrease PCD (9.8 [8.5-11.9] vs. 8.8 [8.2-9.6] mm.mm-2, p = 0.08). Fifteen patients (50%) died within 30 days after admission. Patients who had low final PCD (≤ 10.3 mm.mm-2; 64%) were more likely to die than patients who had preserved PCD (>10.3 mm.mm(-2); mortality 72% vs. 17%, p = 0.003).

Conclusion: This study demonstrates the effects of commonly used inotropic agents on parameters of tissue perfusion in patients with cardiogenic shock. Despite hemodynamic optimization, tissue perfusion was not sufficiently restored in most patients. In these patients, mortality was high. Interventions directed at improving microcirculation may eventually help bridging the gap between improved hemodynamics and dismal patient outcome in cardiogenic shock.

Figure 1. Changes in perfused capillary density following infusions of dobutamine (median 60 minutes), enoximone (median 85 minutes), and norepinephrine (median 75 minutes) at the individual patient level.

↑, increase of parameter following inotropic therapy in terms of percentage relative to baseline. The reference value of perfused capillary density is indicated by the red dashed line (ie, 10.3 mm.mm⁻²). Values greater than this reference are to be considered as preserved capillary density, values below or equal to this reference reflect impaired capillary density .

Figure 2. Thirty-day mortality according to final perfused capillary density.

In the subgroup of patients (n = 18) with low perfused capillary density (ie, ≤10.3 mm.mm⁻²), 13 patients died, whereas in the subgroup of patients (n = 12) with preserved capillary density (ie, >10.3 mm.mm⁻²) 2 patients died (p = 0.003).