Massimo Goracci

Miniaturized Cardiopulmonary Bypass and Acute Kidney Injury in Coronary Artery Bypass Graft Surgery

BACKGROUND Acute kidney injury (AKI) is one of the most important complications after on-pump coronary artery bypass graft surgery (CABG). Miniaturized cardiopulmonary bypass (mini-CPB) systems have been developed to allow the ease of on-pump surgery but tempering the disadvantages. Whether mini-CPB reduces the incidence of AKI remains to be determined. METHODS Using a propensity score matched analysis, we investigated the occurrence of AKI among patients undergoing CABG on mini-CPB (n = 104) versus conventional CPB (n = 601). Acute kidney injury was defined according to the recent Acute Kidney Injury Network classification. RESULTS Overall, acute kidney injury developed in 274 of 705 patients (38.8%). A total of 27 of 705 patients (3.8%) required renal replacement therapy. The median postoperative length of intensive care unit stay in survivors with AKI was 5.4 (3.9 to 6.8) days compared with 2.0 (1.0 to 3.0) days for patients without AKI (p = 0.0002). The overall incidence of AKI for patients undergoing mini-CPB was 30 of 104 (28.8%) compared with 244 of 601 (40.5%) for patients undergoing conventional CPB (p = 0.03). In the propensity score matched-pair statistical analysis, mini-CPB was independently associated with a decreased incidence of AKI (adjusted odds ratio [OR] 0.61; 95% confidence interval [CI]: 0.38 to 0.97). Other variables independently associated with AKI were preoperative glomerular filtration rate (OR 0.988 for 1 mL.min(-1).1.73 m(-2) increase; 95% CI: 0.98 to 0.99), postoperative red blood cell transfusion (OR 1.58; 95% CI: 1.12 to 2.23); CPB time (OR 1.005 for 1-minute increase; 95% CI: 1.0 to 1.009), and postoperative low output syndrome (OR 1.72; 95% CI: 1.23 to 2.41). CONCLUSIONS The present study showed that mini-CPB is associated with a lower incidence of AKI when compared with conventional CPB among patients undergoing CABG.

Is minimized extracorporeal circulation effective to reduce the need for red blood cell transfusion in coronary artery bypass grafting? Meta-analysis of randomized controlled trials

DISCUSSION The patient described had parietal pericardial bovine bioprostheses in both the mitral and aortic valve positions for 77 months and during that period developed huge quantities of calcium on the cusps of the bioprosthesis in the aortic valve position and only small quantities of calcium on the cusps of the bioprosthesis in the mitral valve position. Because the closing pressure on the mitral bioprosthesis is usually about a third higher than that on the aortic bioprosthesis (peak left ventricular systolic pressure vs end-diastolic aortic pressure; normally approximately 120 vs 80 mm Hg), it might be expected that the degeneration of a bioprosthesis in the mitral position would be greater (more calcium and more tears) and more rapid than that of a bioprosthesis in the aortic position, but the opposite was the case in the patient described herein. Why might that be the case? Some possibilities include the following:

Neutrophil gelatinase-associated lipocalin levels after use of mini-cardiopulmonary bypass system

Neutrophil gelatinase-associated lipocalin (NGAL) has been implicated as an early predictive urinary biomarker of ischemic acute kidney injury (AKI). The aim of this study was to compare the effects of miniaturized cardiopulmonary bypass system (MCPB) vs. standard cardiopulmonary bypass system (SCPB) system on kidney tissue in patients undergoing myocardial revascularization using urinary NGAL levels as an early marker for renal injury. Sixty consecutive patients who underwent myocardial revascularization were studied prospectively. An SCPB was used in 30 patients (group A) and MCPB was used in 30 patients (group B). The SCPB group but not the MCPB group showed a significant NGAL concentration increase from preoperative during the 1st postoperative day (169.0+/-163.6 ng/ml in the SCPB group vs. 94.1+/-99.4 ng/ml in the MCPB group, P<0.05, respectively). Two patients in the SCPB group developed AKI and underwent renal replacement therapy; no patient in MCPB developed AKI. The MCPB system is safe in routine clinical use. Kidney function is better protected during MCPB as demonstrated by NGAL levels. NGAL represents an early biomarker of renal failure in patients undergoing cardiac surgery and the valuation of its concentration can aid in medical decision-making.

Intraoperative Continuous Venovenous Hemofiltration during Coronary Surgery

Postoperative continuous venovenous hemofiltration decreases acute renal failure in patients with moderate renal dysfunction undergoing coronary artery bypass grafting, but it prolongs intensive care unit stay. We developed a simple method to connect a hemofiltration machine to the cardiopulmonary bypass system. To evaluate the benefit of intraoperative hemofiltration, 124 consecutive patients (mean age, 67 ± 6 years) with moderate renal dysfunction were studied. Surgery was preformed between January 2005 and May 2007. On-pump coronary artery bypass with hemofiltration was carried out in 40 patients (group A), 44 had on-pump coronary artery bypass without hemofiltration (group B), and 40 had off-pump coronary artery bypass (group C). Postoperative acute renal failure was defined as either renal failure requiring dialysis or ≥50% decline from the baseline glomerular filtration rate but not requiring dialysis. The 3 groups had similar demographic data and preoperative renal function. After adjusting for covariates and propensity scores, multivariate analysis showed that intraoperative hemofiltration and off-pump surgery protected postoperative renal function. Independent risk factors for postoperative renal dysfunction were age >70 years, left ventricular ejection fraction <35%, and the preoperative glomerular filtration rate.

Reduction of Early Postoperative Morbidity in Cardiac Surgery Patients Treated With Continuous Veno–Venous Hemofiltration During Cardiopulmonary Bypass

Cardiac surgery with cardiopulmonary bypass is associated with a systemic inflammatory response syndrome. The major clinical features of this include a reduction of pulmonary compliance and increased extracellular fluids, with increased pulmonary shunt fraction similar to acute respiratory distress syndrome, thus resulting in prolonged mechanical ventilation time (VAM) and intensive care unit length of stay (ICU STAY). We evaluated the feasibility of an intraoperatory cardiopulmonary bypass (CPB) circuit connected with a monitor for continuous veno-venous hemofiltration (CVVH) to ameliorate pulmonary function after open heart surgery reducing VAM and ICU STAY. Forty patients undergoing elective coronary artery bypass grafting were randomized at the time of surgery into a control group (20 patients who received standard cardiopulmonary bypass) and a study group (20 patients who received CVVH during cardiopulmonary bypass). The analysis of postoperative variables showed a significative reduction of VAM in treated group (CVVH group mean 3.55 h +/- 0.85, control group 5.8 h +/- 0.94, P < 0.001) and ICU STAY (CVVH group mean 29.5 h +/- 6.7, control group 40.5 h +/- 6.67, P < 0.001). In our experience, the use of intraoperatory CVVH during cardiopulmonary bypass is associated with lower early postoperative morbidity.

Preoperative creatinine clearance as a predictor of short-term outcomes after cardiac surgery: A cohort study for the comparison between the cockroft-gault and modification of diet in renal disease formulae

Background Preoperative renal function is an important risk factor in cardiac surgery for long-term and short-term outcomes. Renal function is best assessed by measuring or calculating the glomerular filtration rate (GFR). Several algorithms using the endogenous marker serum creatinine have been developed to estimate renal function. These include the Cockcroft and Gault and the modification of diet in renal disease (MDRD) formulae. The aim of this study was to compare the predictive power of the two formulae towards short-term outcomes after cardiac surgery, such as the length of intensive care unit (ICU) stay, the length of mechanical ventilation time, and the length of in-hospital stay. Methods One hundred and fifty patients undergoing cardiac surgery and not affected by renal failure were followed up until hospital discharge. We collected data before, during and after surgery. Before surgery data consisted of date of birth, sex, height, weight, plasma creatinine level; during surgery data consisted of type of intervention (including number of bypasses, if any), cardiopulmonary bypass time and aortic cross-clamp time; after surgery data consisted of length of ICU stay, mechanical ventilation time, length of in-hospital stay after intensive-care discharge (ward stay), incidence of acute renal failure (expressed as the need for dialysis) and mortality. The dataset was analyzed using Cox regression. Results The average mechanical ventilation time, ICU stay and ward stay were 11 h, 49 h and 10 days, respectively. After having adjusted for chronic obstructive pulmonary disease, diabetes and postsurgical dialysis, the GFR calculated with the Cockcroft and Gault formula appeared to be a predictor of ICU stay and mechanical ventilation time with very strong evidence (P = 0.002 and <0.001, respectively) and a predictor of ward stay with some evidence (P = 0.062). After an identical case-mix adjustment, the GFR calculated with the MDRD formula appeared to be a predictor of ICU stay with strong evidence (P = 0.007), a predictor of mechanical ventilation time with some evidence (P = 0.075) and it has shown no evidence of predicting ward stay (P = 0.197). Conclusion There is an indication that the Cockcroft and Gault formula could be more powerful than the MDRD formula for the preoperative prediction of early postoperative clinical outcomes in cardiac surgery, in patients not affected by renal failure. Further research is needed to confirm this result.

A circuit to perform a combined ultrafiltration procedure in pediatric open heart surgery

Cardiopulmonary bypass (CPB) induces an increased capillary permeability and tissues water content due to hemodilution and the inflammatory response, resulting in organ dysfunction. The reduction of the water accumulation and inflammatory response can be achieved by employing ultrafiltration during CPB. Recently we developed a simple CPB circuit for ultrafiltration using the aortic venting tube as an inlet line. Such a technique offers the advantages of performing a combined ultrafiltration procedure and eliminating the danger of air embolism. We employed this circuit in 12 consecutive pediatric patients undergoing open heart surgery.

Miniaturized versus conventional cardiopulmonary bypass in patients undergoing coronary artery bypass surgery: impact on lymphocyte depletion and sternal wound healing.

To reduce deleterious effects of C-CPB novel concepts have been developed based on miniaturized cardiopulmonary bypass (Mini-CPB) with closed circuits, low priming volumes and optimized perfusion system. In CABG surgery, it has previously shown that the use of Mini-CPB can reduce systemic inflammation compared to C-CPB [25] and so attenuate the pathologic effects of C-CPB.