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Description / Table of Contents: Summary Background: Hypotension during induction of anesthesia is frequently observed in patients undergoing coronary artery bypass grafting (CABG). On the other hand, a reduction of intravascular volume has been described in patients suffering from cardiovascular diseases. The aim of this study is to evaluate the influence of intrinsic volume deficit on the extent of arterial hypotension during induction of anesthesia. Therefore, according to the measured intravascular volume, the examined patients were divided into a normovolemic and a hypovolemic group. The hemodynamic changes have been compared between these two groups. Methods: Thirty-eight patients with normal left-ventricular function scheduled for CABG were investigated. Blood volume was calculated from hematocrit and plasma volume determined by the dye-dilution method with Indocyanine-green (ICG). According to the measured blood volumes the patients were divided into a hypovolemic (HV) and a normovolemic (NV) group of at least 13 patients per group. Twelve patients with intermediate blood volumes were not included in the statistical evaluation. Hemodynamic data were measured three times: before and after induction of anesthesia as well as after endotracheal intubation. Results: Due to division of the patients, body weight (BW) indexed blood volume (mean ± SD) was 68.5 ± 3.73 ml · kg;–1 in the NV group and 54.8 ± 4.86 ml · kg;–1 in the HV group (p 〈 0.001). At all measurements, heart rate was significantly lower and pulmonary capillary wedge pressur, pulmonary artery pressure, and central venous pressure significantly higher in the NV group than in the HV group. In contrast, the values of mean arterial pressure (MAP), systemic vascular resistance (SVR) and cardiac index (CI) did not differ significantly between both groups at any time. Correlation analysis revealed that the extent of arterial hypotension was mainly influenced from MAP before induction of anesthesia (r = 0.6674, p 〈 0.001). Conclusions: There is no difference in the decrease of MAP after induction of anesthesia between the hypovolemic and the normovolemic group. Arterial hypotension is caused mainly by pre-induction MAP which should be noted for treatment.

Description / Table of Contents: Summary Introduction: Neuropsychological morbidity following cardiac surgery of congenital heart disease (CHD) most likely considered to be due to alterations of cerebral oxygenation and hemodynamics could possibly be in part prevented by early detection by means of continous non-invasive monitoring during and after cardiac surgery. Measurement of regional cerebral blood saturation (rSO2) by near infrared spectroscopy (NIRS) mays provide qualitative information on cerebral oxygen supply and consumption. The aim of the sutdy was to investigate the relationship between the change in rSO2 and other hemodynamic parameters during the different stages of CPB in a heterogeneous group of infants and children undergoing corrective and palliative cardiac surgery by means of full flow CPB. Methods: 50 children and infants (15 infants with cyanotic CHD, median age 18 days (5 days–7 months); 15 children with cyanotic CHD, median age 4 years (1–9 years); 20 children with non-cyanotic CHD, median age 4 years (1–16 years)) undergoing surgical correction by means of full flow cardiopulmonary bypass (CPB) (120–150 ml/kg/BW) with moderate hypothermia (24±6°C) and alpha stat method were included in this study. Total circulatory arrest was used only in 3 infants. Continuous measurement of rSO2 was performed using a two channel cerebral oximeter (INVOS 31000A®, somanetics, USA). The sensor with a light source and superficial and deep received was placed in standardized localization at the left temporal head side. Hemodynamic parameters were simultaneously documented. Results: Before CPB the mean values of rSO2 in children with cyanotic congenital heart disease (CHD) were significantly lower (p=0.002) than those with non-cyanotic CHD. After onset of cardiopulmonary bypass (CPB) there was a gradual fall in rSO2 with achieved minimal values within 14–40 minutes (p〈0.01). During CPB these values of rSO2 were nearly 8–10% lower, particularly in the younger infants. After the end of CPB there was nearly subsequent restoration of these values in the older children. After rewarming and cessation of CPB rSO2 decreased up to 15% in individual patients particularly in young infants reflecting a higher O2 consumption. There relationship between the change in rSO2 and mean arterial pressure (MAP), central venous pressure (CVP), hemoglobin concentration (Hb) and temperature was in part significant in all infants during the period of monitoring. Conclusion: Change of cerebral oxygenation independent of the change in conventional hemodynamic parameters and arterial blood oxygenation suggests the necissity of separate monitoring of cerebral oxygenation and hemodynamics during and after cardiac surgery in infants and children. Further follow up studies are necessary to evaluate the neurological significance of the magnitude and duration of the decreased change in rSO2 during and after.

Description / Table of Contents: Zusammenfassung Fragestellung: Das Ziel diese prospektiven Studie war, die Serumkinetik des hirnspezifischen Markers Protein S-100, eines Gliazell- und Astrozytenproteins, in Beziehung zur kontinuierlich registrierten zerebralen Oxygenierung vor und nach Korrekturoperationen angeborener Herzfehler zu evaluieren.¶   Methodik: Die regionale zerebrale Hämoglobin-Sättigung wurde mit Hilfe der Nahinfrarotspektroskopie (INVOS 3100A, Somanetics®, USA) bestimmt und das Protein S-100 mittels eines doppelseitigen Radioimmunassays analysiert (Sangtec® 100 IRMA, Bromma, Schweden).¶   Ergebnisse: Das Protein S-100 war bei allen Kindern ohne nachweisbare neurologische Komplikationen nach Ende der extrakorporalen Zirkulation um 2 Standardabweichungen des präoperativen Ausgangswertes erhöht gefunden (p〈0,0001). Die maximalen Serum-S-100-Konzentrationen korrelierten signifikant mit dem Alter (r=–0,75, p〈0,0001) und Gewicht (r=–0,72, p=0,005) der Kinder, der Bypasszeit (r=0,44, p=0,005) und der minimalen rektalen Temperatur (r=–0,67, p=0,004) während der extrakorporalen Zirkulation. Ein statistischer Zusammenhang fand sich zwischen dem postoperativen Serumspiegel des Protein S-100 und dem Abfall der regionalen zerebralen Hämoglobin-Sättigung während der Reperfusion (r=–0,37, p=0,02) und am Ende der extrakorporalen Zirkulation (r=¶–0,42, p=0,008).¶   Schlußfolgerung: Die Astrogliazellen scheinen auf die extrakorporale Zirkulation mit einer Expression des Protein S-100 zu reagieren. Eine Membranschädigung im endothelialastrozytären Zellkomplex der Blut-Hirnschranke könnte die Freisetzung des Proteins in die Blutstrombahn erklären. Beeinflussende Faktoren scheinen geringes Alter, Länge der extrakorporalen Zirkulation, Grad der Hypothermie und mögliche Reduktion der postoperativen zerebralen Oxygenierung zu sein.