Relation between mixed venous oxygen saturation and cerebral oxygen saturation measured by absolute and relative near-infrared spectroscopy during off-pump coronary artery bypass grafting.

BACKGROUND: We hypothesized that previously reported contradictory results regarding the equivalence of mixed venous (Smv(O(2))) and cerebral (rS(c)O(2)) oxygen saturation might be related to time delay issues and to measurement technology. In order to explore these two factors, we designed a prospective clinical study comparing with relative (INVOS(®)) and absolute (Foresight(®)) rS(c)O(2) measurements. METHODS: Forty-two consenting patients undergoing elective off-pump coronary artery bypass grafting were included. Two INVOS and two Foresight sensors continuously registered rS(c)O(2). Smv(O(2)) was measured continuously via a pulmonary artery catheter. Data were assessed by within- and between-group comparisons and correlation analysis. RESULTS: A similar time delay of 19 (4) and 18 (4) s was found for compared with rS(c)O(2) measurements by Foresight and INVOS, respectively, during haemodynamic changes. After adjusting for this time delay, the correlation between Smv(O(2)) and rS(c)O(2) increased from r=0.25 to 0.75 (P<0.001) for Foresight, and from r=0.28 to 0.73 (P<0.001) for INVOS. Comparison of Foresight and INVOS revealed significant differences in absolute rS(c)O(2) values (range 58-89% for Foresight and 28-95% for INVOS). Changes in rS(c)O(2) in response to acute haemodynamic alterations were significantly more pronounced with INVOS compared with Foresight (P<0.001). CONCLUSIONS: Considering the important time delay with Smv(O(2)), rS(c)O(2) seems to reflect more appropriately acute haemodynamic alterations. This might suggest its use as a valid alternative to invasive monitoring of tissue oxygen saturation. Relative and absolute rS(c)O(2) measurements demonstrated significant differences in measured rS(c)O(2) values and in the magnitude of rS(c)O(2) changes during haemodynamic alterations.

Active or passive bio-coating: does it matters in extracorporeal circulation?

BACKGROUND: Two types of surface coating for cardiopulmonary bypass (CPB) are used: bioactive (heparin, nitric oxide) and biopassive (albumin, polyethyleneoxide (PEO), phosphorylcholine). When haemocompatible coatings are combined with the separation of pleuro-pericardial aspiration, attenuation of both the coagulation and complement cascades, as well as better platelet preservation, has been demonstrated. This study wants to investigate if the combination of a bioactive with a biopassive coating (unfractionated heparin embedded in a phosphorylcholine matrix) combines the beneficial effects of both approaches. MATERIALS AND METHODS: Thirty patients undergoing elective CABG were prospectively randomized into two groups of 15 patients. The sole exclusion criterion was an ejection fraction of less than 40%. In the control group (PC), the whole CPB circuit was coated with phosphorylcholine (PC). In the study group (XPC), unfractionated heparin was embedded in the PC matrix of the oxygenator and arterial line filter. RESULTS: No differences were found for haemolytic index, thrombin-anti-thrombin complex (TAT), IL-6, IL-10 and blood loss. PF4 plasma concentration increased from 27.6±22.0 IU/mL to 165.7±43.9 IU/mL (p<0.001) at 15 minutes of CPB in the PC and from 16.0±9.7 IU/mL to 150.9 ± 61.3 IU/mL (p<0.001) in the XPC group. Terminal complement complex (TCC) increased over time in both groups until the end of CPB (Figure 2A). Within each group, TCC generation was statistically significantly higher after the release of the aortic cross-clamp (p<0.001) and at the end of CPB (p<0.001). Total TCC generation was statistically significantly higher in the XPC group compared to the PC group (p=0.026). The difference was statistically significant after the release of the aortic cross-clamp (p=0.005) and at the end of CPB (p=0.001). CONCLUSIONS: Based on our results, there is no additional benefit in combining phosphorylcholine with unfractionated heparin in elective patients undergoing coronary artery bypass grafting (CABG). Massive haemodilution leads to enhanced complement activation.

Off-pump coronary artery grafting in patients necessitating multiple distal anastomoses.

OBJECTIVES: Off-pump surgery has become a valuable alternative if a small number of distal anastomoses is required. The aim of the present study was to test the hypothesis that outcome is not altered in multiple distal anastomoses. MATERIAL AND METHODS: During a 4 year period, 350 patients were operated off-pump. 187 patients received one or two distal anastomoses (group A), and 163 patients received more than two distal anastomoses (group B). Pre-operative characteristics, intra-operative details and postoperative outcome were reviewed. RESULTS: In group A, 1.8 +/- 0.4 distal anastomoses were performed, versus 3.2 +/- 0.5 in group B (P < 0.001). There were more sequential distal anastomoses in group B (1.09 in group A versus 1.38 in group B) with a wider use of right internal thoracic and radial arteries. There were more anastomoses performed on the lateral (89% vs. 45%) and on the inferior wall (65% vs. 16%) in group B, compared with group A. The operation time was significantly longer (206 +/- 75 minutes versus 158 +/- 33 minutes) and the operative blood loss significantly higher (748 +/- 516 ml versus 509 +/- 361 ml) in group B. Total blood loss, transfusion requirements, neurological disfunction, hospital stay, troponine I level, postoperative infarction and 30 days mortality did not differ significantly between groups. There were 11 conversions (3.1%), 3 patients in group A and 8 patients in group B (NS). Most conversion occurred imperative while performing an anastomosis on the anterior wall. CONCLUSION: Beating heart surgery with multiple distal anastomoses, can be performed without increased myocardial damage, postoperative morbidity or hospital mortality. Lateral wall grafting could not be identified as a trigger for conversion.