We hypothesized that previously reported contradictory results regarding the equivalence of mixed venous ( ) and cerebral (rS_cO₂) 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_cO₂ measurements. Forty-two consenting patients undergoing elective off-pump coronary artery bypass grafting were included. Two INVOS and two Foresight sensors continuously registered rS_cO₂. was measured continuously via a pulmonary artery catheter. Data were assessed by within- and between-group comparisons and correlation analysis. A similar time delay of 19 (4) and 18 (4) s was found for compared with rS_cO₂ measurements by Foresight and INVOS, respectively, during haemodynamic changes. After adjusting for this time delay, the correlation between and rS_cO₂ 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_cO₂ values (range 58–89% for Foresight and 28–95% for INVOS). Changes in rS_cO₂ in response to acute haemodynamic alterations were significantly more pronounced with INVOS compared with Foresight (P<0.001). Considering the important time delay with , rS_cO₂ 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_cO₂ measurements demonstrated significant differences in measured rS_cO₂ values and in the magnitude of rS_cO₂ changes during haemodynamic alterations.

Albeit being a simple surgical procedure, adverse outcomes with the modified Blalock-Taussig shunt (MBTS) are commonly reported in generalizing terms, independent of the underlying heart disorder. From August 1995 to December 2013, a total of 150 children underwent an MBTS for tetralogy of Fallot (TOF; n = 44, 29%), pulmonary atresia with ventricular septal defect (PA/VSD; n = 28, 19%), pulmonary atresia with intact ventricular septum (PA/IVS; n = 17, 11%), transposition of the great arteries with ventricular septal defect (TGA/VSD) with pulmonary stenosis (PS; n = 12, 8%), Ebstein malformation (n = 2, 1%), and complex univentricular anomalies (n = 47, 31%). Outcome analysis focused on operative mortality and survival until shunt takedown, adjusted to the underlying disease. In-hospital mortality was 8.7% (n = 13), and interstage mortality was 5.1% (n = 7), resulting in 86.1% survival to the next surgery. Hospital mortality was 14% in PA/VSD, 13% in univentricular heart, and 18% in PA/IVS, while no mortality was observed in TOF, TGA/VSD/PS, and Ebstein disease. A shunt-related complication was observed in 18% (n = 27) of the children, including acute thrombosis (n = 7, 5%), shunt stenosis (n = 3, 2%), overshunting (n = 7, 5%), and pulmonary artery stenosis (n = 10, 7%). Multivariate analysis of shunt-dependent time survival identified a shunt complication occurring in a univentricular circulation (hazard ratio [HR] 4.10, 95% confidence interval [CI] = 1.05-17.43, P = .01) and increased shunt size-to-weight ratio (HR 2.72, 95% CI = 0.80-9.18, P = .04) as risk factors. Shunt thrombosis was also a negative outcome predictor in PA/VSD, when requiring associated unifocalization (P = .05). This study shows that the outcome of palliation with the MBTS is importantly affected by the occurrence of a shunt-related complication, whose circulatory effect is even more dismal in single ventricle hearts. Since an increased shunt size-to-weight ratio additionally compromises the shunt-dependent survival, it emphasizes that the choice of the shunt with regard to size as well as surgical approach remains critical.

Many cardiac procedures using cardiopulmonary bypass (CPB) still require intraoperative transfusion. Retrograde autologous priming (RAP) has been introduced to decrease haemodilution and the blood transfusion rate. This study is designed to determine the influence or RAP on intraoperative haematocrit, transfusion and its clinical consequences. The RAP effect was retrospectively studied in 753 patients during contemporary cardiac surgery, targeting a haematocrit of 25%. Multivariate linear regression analysis was performed to identify the independent factors influencing intraoperative haematocrit, transfusion rate and transfusion quantity. RAP was used in 498 patients and compared with 255 controls. RAP decreased the haemodilution level (nadir haematocrit 26.8 standard deviation [SD] 4.0% in RAP vs 25.8 SD 3.6% in controls; P = 0.001) and transfusion frequency (26.1 vs 33.3%, P = 0.04), despite smaller patients (body surface area [BSA] 1.86 SD 0.20 m² vs 1.91 SD 0.21 m² in RAP vs controls; P = 0.002) with lower preoperative haematocrit (38.9 SD 4.4% vs 40.5 SD 4.6%; P < 0.001). Optimal RAP volume was overall 475 ml (ROC area 0.55; 95% confidence interval [CI] 0.50–0.60; P = 0.04) and 375 ml in patients with BSA <1.7 m² (ROC area 0.63; 95% CI 0.54–0.73; P = 0.008) to decrease the transfusion incidence. Multivariate analysis revealed RAP volume as a significant determinant of nadir haematocrit (β = 0.003, 95% CI 0.002–0.004, P < 0.001) and transfusion rate (odds ratio (OR) = 0.997, 95% CI 0.996–0.999, P < 0.001), independent of BSA, gender and preoperative haematocrit. Retrograde autologous priming is an effective adjunct to decrease the blood transfusion rate, coping with the CPB-related haemodilution and its adverse clinical effects. A RAP volume individualized to each patient offers most benefit as part of a multidisciplinary blood conservation approach.