Extracorporeal Membrane Oxygenation Improving Survival and Alleviating Kidney Injury in a Swine Model of Cardiac Arrest Compared to Conventional Cardiopulmonary Resuscitation

Background: Acute kidney injury (AKI) frequently occurs in cardiopulmonary resuscitation patients. Studies comparing the effects of extracorporeal membrane oxygenation (ECMO) with conventional cardiopulmonary resuscitation (CCPR) on AKI were rare. This study aimed to compare the effects of ECMO with those of CCPR on survival rate and AKI and explore the underlying mechanisms in a swine model of cardiac arrest (CA). Methods: Sixteen male pigs were treated with ventricular fibrillation to establish CA model and then underwent CCPR (CCPR group, n = 8) or ECMO during cardiopulmonary resuscitation (ECPR group, n = 8). The study endpoints were 6 h after return of spontaneous circulation (ROSC) or death. Serum and urine samples were collected at baseline and during the 6 h after ROSC. The biomarkers of AKI were detected by enzyme-linked immunosorbent assay. The apoptosis of renal tubular epithelial cells was discovered by transmission electron microscope (TEM) and terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Apoptosis-related genes were detected by immune-staining and Western blotting. Data were compared by Student's t-test. Results: All pigs in ECPR group were successfully resuscitated with a higher 6-h survival rate (8/8) compared to CCPR group (6/8). The expressions of AKI biomarkers including neutrophil gelatinase-associated lipocalin (NGAL), tissue inhibitor of metalloproteinase2 (TJIMIP2), insulin-like growth factor-binding protein 7 (IGFBP7), liver fatty acid-binding protein (LFABP), and kidney injury molecule 1 (Kim-1) were all increased along with the time after ROSC in both groups and lower in ECPR group compared with CCPR group. Especially, products of urinary TIMP and IGFBP levels (TIMP*IGFBP) were significantly lower at ROSC4 (0.58 +/- 0.10 ng(2)/ml(2) vs. 1.18 +/- 0.38 ng(2)/ml(2), t = 4.33, P = 0.003) and ROSC6 (1.79 +/- 0.45 ng(2)/ml(2) vs. 3.00 +/- 0.44 ng(2)/ml(2), t = 5.49, P < 0.001); urinary LFABP was significantly lower at ROSC6 (0.74 +/- 0.06 pg/ml vs. 0.85 +/- 0.11 pg/ml, t = 2.41, P = 0.033); and urinary Kim-l was significantly lower at ROSC4 (0.66 +/- 0.09 pg/ml vs. 0.83 +/- 0.06 pg/ml, t = 3.99, P = 0.002) and ROSC6 (0.73 +/- 0.12 pg/ml vs. 0.89 +/- 0.08 pg/ml, t = 2.82, P = 0.016). Under light microscope and TEM, the morphological injures in renal tissues were found to be improved in ECPR group. Moreover, apoptosis was also alleviated in ECPR group. Conclusions: Compared with CCPR, ECMO improves survival rate and alleviates AKI in a swine model of CA. The mechanism of which might be via downregulating AKI biomarkers and apoptosis in kidney.