Bovine hemoglobin increases skeletal muscle oxygenation during 95% artificial arterial stenosis.

BACKGROUND: This study investigates the effect of a stroma-free ultrapurified bovine hemoglobin solution (HBOC) on skeletal muscle tissue oxygenation in comparison with hetastarch during nearly complete arterial stenosis. METHODS: Fourteen foxhounds were intravenously anesthetized and mechanically ventilated with 30% oxygen in air. Catheters were inserted into the right femoral artery and vein for measurements of hemodynamic parameters and blood gas sampling. Arterial blood flow of the left popliteal artery was measured by means of an electromagnetic flow probe. Skeletal muscle tissue oxygen tension (tpO2) was measured in the left gastrocnemius muscle by using a stepwise driven polarographic needle probe creating histograms from 200 single tpO2 measurements. After isovolemic hemodilution with Ringer's lactate solution to a hematocrit of 25%, a 95% artificial stenosis of the popliteal artery was established. The animals then randomly received two applications of either 50 ml HBOC (molecular weight, 32,000 to 500,000; hemoglobin, 13 +/- 1 gm/dl-1) or 200 ml 6% hetastarch 200,000/0.5. Variables were measured at baseline, after hemodilution, 30 minutes after stenosis, and 15 minutes after two applications of the respective compound. RESULTS: Demographic data, muscle temperature, and arterial blood gases did not differ between groups. With the exception of higher mean arterial and mean pulmonary artery pressures in HBOC-treated animals, hemodynamics did not differ between groups. In both groups oxygen delivery and oxygen consumption of the muscle decreased in parallel to the decreasing blood flow during arterial stenosis. In contrast, oxygen extraction ratio increased after infusion of HBOC and was higher after the second application when compared with hetastarch-treated animals (p < 0.05). During stenosis tpO2 was decreased in both groups when compared with baseline (p < 0.001). Mean tpO2 remained at decreased levels after administration of hetastarch but increased to nearly baseline values after HBOC treatment (p < 0.001). CONCLUSIONS: The data suggest that increased oxygen extraction in the HBOC group is associated with improved skeletal muscle tissue oxygenation during severe arterial stenosis.

[Quality assured ultrasound simulation training for the detection of fetal malformations--can a training benefit be evidenced?]. / Qualitätsgesichertes Ultraschall-Simulator-Training zur Erkennung fetaler Fehlbildungen--Lässt sich ein Lernerfolg durch das Training am Ultraschall-Simulator belegen?

INTRODUCTION: The factual sonographic training in obstetrics differs in Germany in a broad range. In this context, a tendency towards minimalistic dealings with this issue prevails. In contrast to this, the provisions of the German maternity guidelines relating to ultrasound clearly define quality oriented requirements serving altogether as a basic sonographic standard which mandatorily has to be met by all German Obstetricians. In order to close this gap between professional education and social demand, a training concept regarding obstetric ultrasound was devised by the German Association of Gynecologists utilizing the ultrasound simulator system. The aim of this study was to evaluate the usefulness and the effectiveness of this method and its potential role and benefit in structured sonographic training. MATERIAL AND METHODS: Between October 2004 and August 2005, 74 obstetric ultrasound training courses according to the ultrasound simulator concept of the Medical School of Hanover were realized in nine federal states of Germany by the German Academy of Gynecology. The aim of these courses was it to procure ultrasound knowledge regarding the structured sonographic exclusion of fetal malformations in a compact manner. As a measure of quality assurance, a standardized questionnaire was issued before and after the courses in order to analyze the benefit of these simulator-based ultrasound courses. RESULTS: The concept found prevailing approval (90 %) at the level of principle, practical implementation and clinical usefulness. 88,2 % of the participants estimated their subjective training effect as being good. The analysis of the questionnaire showed a statistically significant improvement of sonographic knowledge. On average, 74.1 % of the questions were answered correctly by the end of the course as opposed to a mere 46.3 % at the beginning. CONCLUSION: Structured ultrasound training courses based on the ultrasound simulator system seem to be able to define a basic quality of training and significantly improves examiners' skills in prenatal medicine possible independent of local or structural factors. Hence they seem to be a suitable instrument to close the gap between the sonographic education worthy of improvement and the existing social demand for efficiacy of obstetric sonography.

[Spatial arrangement and inner wall surface of ocular vessels. Scanning electronmicroscopy of vascular casts (author's transl)]. / Untersuchungen zur räumlichen Struktur und Gefässinnenfläche von Augengefässen. Rasterelektronenmikroskopische Betrachtung von Gefässausgusspräparaten.

Vascular corrosion casts of the rabbit eye vessels were studied by scanning electron microscopy. Compared with light micrescopy, this method provides great depth of field and better contrast. Thus the pictures are more informative and documentation is easier. The high resolving power of scanning electron microscopy of suitable vascular casts allows the study of structures of the inner vessel wall. Such information could not be retrieved from these replicas until now.

[Bovine hemoglobin. HBOC-201 causes a reduction of the oxygen partial pressure in poststenotic skeletal muscle]. / Bovines Hämoglobin. HBOC-201 verhindert eine Reduktion des Sauerstoffpartialdrucks im poststenotischen Skelettmuskel.

UNLABELLED: We investigated the effects of ultrapurified polymerized bovine hemoglobin (HBOC-201) on skeletal muscle tissue oxygen tension when applied before establishment of a nearly complete arterial stenosis. METHODS: Twelve foxhounds were anaesthetized IV and mechanically ventilated with 30% oxygen in air. Catheters were inserted into the right femoral artery and vein for measurements of haemodynamic parameters and blood-gas sampling. Arterial blood flow of the left popliteal artery was measured by an electromagnetic flow probe. Skeletal muscle tissue oxygen tension (tpo2) was measured in the left gastrocnemic muscle using a stepwise-driven polarographic needle probe, creating histograms from 200 single tpO2 measurements. Following isovolaemic haemodilution with Ringer's solution to a target haematocrit of 20%, the animals were randomly assigned to receive either 200 ml of predonated fresh blood (group 1) or 200 ml of HBOC-201 (MW 32,000-500,000; Hb 13 +/- 1 g-dl-1, group 2). After a 15-min stabilization period, a 95% artificial stenosis of the left popliteal artery was established. While animals of group 1 received two applications of 200 ml 6% hetastarch (HES, 200,000; 0.5), animals of group 2 received 200 ml Ringer's solution 45 and 75 min after establishment of the arterial stenosis, respectively. Variables were measured at baseline, after haemodilution and application of the respective compound, and 30, 60 and 90 min after establishment of the stenosis. RESULTS: Demographic data, muscle temperature and arterial blood gases did not differ between groups. With the exception of a higher mean pulmonary artery pressure in HBOC-201-treated animals, haemodynamics did not differ between groups. In both groups oxygen delivery and oxygen consumption of the muscle decreased in parallel to the decreasing blood flow during arterial stenosis. In contrast, oxygen extraction ratio increased after infusion of HBOC-201 and remained unchanged during stenosis (P < 0.05). In group 1, the tpO2 decreased during stenosis when compared to baseline (P < 0.001) and remained decreased after administration of HES. In contrast, administration of 200 ml of HBOC-201 before establishment of the arterial stenosis sustained the tpO2 values at nearly baseline levels during stenosis. Skeletal muscle tissue oxygen tension was higher after HBOC-201 infusion during stenosis when compared to HES infusion (P < 0.001). CONCLUSION: These data suggest that haemoglobin solutions can reach poststenotic tissues. The increased oxygen extraction after application of HBOC-201 is associated with improved skeletal muscle oxygen tension during severe arterial stenosis.

Bovine haemoglobin is more potent than autologous red blood cells in restoring muscular tissue oxygenation after profound isovolaemic haemodilution in dogs.

PURPOSE: This study compares the effects of stored red cells, freshly donated blood and ultrapurified polymerized bovine haemoglobin (HBOC) on haemodynamic variables, oxygen transport capacity and muscular tissue oxygenation after acute and almost complete isovolaemic haemodilution in a canine model. METHODS: Following randomization to one of three groups, 24 anaesthetized Foxhounds underwent isovolaemic haemodilution with 6% hetastarch to haematocrit levels of 20%, 15% and 10% before they received isovolaemic stepwise augmentation of 1 g.dl-1 haemoglobin. In Group 1, animals were given autologous stored red cells which they had donated three weeks before. In Group 2, animals received freshly donated blood harvested during haemodilution. In Group 3, animals were infused with HBOC. Skeletal muscle tissue oxygen tension was measured with a polarographic 12 mu needle probe. RESULTS: In all groups, heart rate and cardiac index were increased with decreasing vascular resistance during haemodilution (P < 0.05). Haemodynamic variables showed a reversed trend during transfusion when compared to haemodilution but remained below baseline (P < 0.05). Arterial and venous oxygen content were changed in parallel to changes of haematocrit and haemoglobin concentrations but were lower in Group 3 than in Groups 1 and 2 (P < 0.05) during transfusion. In contrast, the oxygen extraction ratio was higher in Group 3 (59 +/- 8%, P < 0.01) at the end of transfusion than in Group 1 (37 +/- 13%) and 2 (32 +/- 5%). In Group 3, mean tissue oxygen tension increased from 16 +/- 5 mmHg after haemodilution to 56 +/- 11 mmHg after transfusion (P < 0.01) and was higher than in Group 1 (41 +/- 9, P < 0.01) and Group 2 (29 +/- 11, P < 0.01). While in Group 3 an augmentation of 0.7 g.dl-1 haemoglobin resulted in restoring baseline tissue oxygenation, higher doses of 2.7 g.dl-1 and 2.1 g.dl-1 were needed in Groups 1 and 2 to reach this level (P < 0.01). CONCLUSION: The results show a higher oxygenation potential of HBOC than with autologous stored red cells because of a more pronounced oxygen extraction.