Central venous oxygen saturation is a good indicator of altered oxygen balance in isovolemic anemia.

BACKGROUND: Red blood cell transfusion is done primarily as a means to improve oxygen delivery (DO2). Current transfusion guidelines are based solely on hemoglobin levels, regardless of actual DO2 need. As central venous oxygen saturation (ScvO2) may reflect imbalances in DO2 and consumption (VO2) the aim of this study was to investigate the value of ScvO2 as an indicator of oxygen balance in isovolemic anemia. METHODS: After splenectomy, anesthetized Vietnamese mini pigs (n = 13, weight range: 18-30 kg) underwent controlled bleeding in five stages (T0-T5). During each stage approximately 10% of the estimated starting total blood volume was removed and immediately replaced with an equal volume of colloid. Hemodynamic measurements and blood gas analysis were then performed. RESULTS: Each stage of bleeding resulted in a significant fall in hemoglobin, T0 : 125 (113-134) to T(5) : 49 (43-55) g/l [T0 : 7.7 (6.9-8.2) to T5 : 3.0 (2.6-3.4) mmol/l]. The O2-extraction (VO2/DO2) increased significantly only from T3 : 35 (21-40) %, P < 0.05. The change of ScvO2 showed a similar pattern and dropped below the physiological threshold of 70% at T4 : 68 (61-76) %. At this point, hemoglobin was below the recommended transfusion trigger value, 59 (53-67) g/l [3.6 (3.3-4.1) mmol/l]. There was a strong significant association between ScvO2< 70%) and VO2/DO2 > 30%): r = -0.71, r² = 0.50, P < 0.001. CONCLUSION: The results of this study show that ScvO2 reflects changes of VO2/DO2 in isovolemic anemia better than Hb alone, therefore it may be used as an additional indicator of blood transfusion in clinical practice.

Correlation between aminoglycoside resistance profiles and DNA hybridization of clinical isolates.

DNA hybridization data and aminoglycoside resistance profiles (AGRPs) were determined for 4,088 clinical isolates from three studies (United States, Belgium, and Argentina). The correlation between susceptibility profiles and hybridization results was determined with nine DNA probes. For each of the seven aminoglycoside resistance profiles which we were able to test, the data suggested at least two distinct genes could encode enzymes which lead to identical resistance profiles. Furthermore, the DNA hybridization data showed that individual strains carried up to six unique aminoglycoside resistance genes. DNA hybridization revealed interesting differences in the frequencies of these genes by organism and by country.