Introduction: 

In cardiogenic shock (CS), persistent microcirculatory impairment despite improved macrocirculatory parameters is associated with poor outcomes. Therapeutic strategies must therefore address both macro- and micro-circulation. Conventional microcirculatory measures have limitations, especially during venoarterial extracorporeal membrane oxygenation support (VA-ECMO). Diffuse correlation spectroscopy (DCS) is a novel optical technique enabling continuous, noninvasive evaluation of microvascular blood flow. This study evaluated DCS for monitoring microcirculation in CS under VA-ECMO.

Methods: 

Seven male beagle dogs (median weight 10.1 kg) underwent CS induction by coronary ligation followed by ventricular fibrillation (VF). VA-ECMO (80-100 mL·kg⁻¹·min⁻¹) was initiated 5 min after VF onset and maintained for 90 minutes under nonpulsatile flow. After stabilization, VA-ECMO flow was reduced from 100 to 30 mL·kg⁻¹·min⁻¹, and mean arterial pressure (MAP) was increased to ≥65 mmHg using vasoconstrictors. Measurements included MAP, cardiac output (CO), and microcirculatory parameters [DCS-derived blood flow index (BFI), perfusion index (PI), skin blood flow (SBF), tissue oxygen saturation, mixed venous oxygen saturation (SvO₂), and lactate].

Results: 

Coronary ligation caused progressive declines in MAP, CO, and microcirculatory indices. MAP (median [interquartile range]) was 109.6 [95.8, 119.7] at baseline and 45.7 [26.3, 51.6] mmHg at CS onset. During VF, PI became unmeasurable while BFI rapidly fell to near zero, detecting peripheral flow loss under nonpulsatile conditions. VA-ECMO initiation restored MAP and SvO₂, with gradual recovery of BFI and SBF. Reducing VA-ECMO flow lowered MAP (64.7 [62.3, 69.9] to 36.4 [34.4, 44.6] mmHg) and BFI (3.6 [3.4, 5.1] to 1.0 [0.8, 1.2] 10⁻⁹·cm²·s⁻¹). Vasopressors increased MAP (83.1 [79.0, 89.1] mmHg) but failed to improve BFI (1.5 [1.3, 2.1] 10⁻⁹·cm²·s⁻¹), indicating persistent microcirculatory impairment.

Conclusions: 

DCS continuously detected microvascular changes during CS and VA-ECMO support regardless of pulsatility. DCS may be useful for early identification of microcirculatory dysfunction and optimization of therapy in CS.