Background:
Extracorporeal CPR (ECPR) is used to provide circulatory stability for organ perfusion and oxygen delivery (DO
2
) after refractory cardiac arrest (CA). Hemodynamic measurements during ECPR may not necessarily indicate adequate perfusion at the microcirculatory level where DO
2
, oxygen consumption (VO
2
), and oxygen exchange (O
2
ER) are most critical. In this study, we used sidestream dark-field imaging to measure total vessel density (TVD) to evaluate sublingual microcirculatory flow in a swine model of refractory CA and ECPR.
Hypothesis:
We hypothesize that TVD can provide real-time assessment of tissue perfusion during post-cardiac arrest ECPR that correlates with traditional measures of tissue oxygenation.
Methods:
Swine (8) were anesthetized and instrumented for hemodynamic monitoring. Ventricular fibrillation (VF) was induced and CPR initiated after 8min. CPR was administered using a combination of manual and mechanical chest compressions. During CPR the femoral vessels were instrumented for delivery of veno-arterial ECPR. ECPR was initiated 45min after arrest to simulate refractory CA. Sublingual TVD was measured at baseline and after 15min, 1, 2, and 3 hours of ECPR.
Results:
A one-way ANOVA showed significant difference between baseline TVD: 12.2(2.3)mm
-1
and at 3 hours into ECPR: 6.4(3.0)mm
-1
(p=0.005). TVD was highly correlated with circuit flow but not with Mean Arterial Pressure (MAP) (r=0.903, p=0.036; r=0.063, p=0.920). In addition, TVD was highly correlated with DO
2
, and lactate, (r= 0.897, p=0.039; r=-0.883, p=0.047) and moderately with VO
2
, O
2
ER, and ScvO
2
(r= 0.776, -0.370, 0.558) respectively.
Conclusion:
TVD appears to provide a reliable real-time assessment of tissue perfusion during post-cardiac arrest ECPR. The relationships between TVD and MAP, and TVD and flow also suggest that optimization of flow may be more important than optimizing pressure to achieve adequate tissue perfusion during ECPR.
Intraoperative Perfusion Assessment in Enhanced Reality Using Quantitative Optical Imaging: An Experimental Study in a Pancreatic Partial Ischemia Model
