Anesthesia and analgesia
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Anesthesia and analgesia · Sep 2016
Observational StudyThe Relationship Between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen During Surgery.
The use of intraoperative pulse oximetry (SpO2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, SpO2 may be reported as 98% when arterial partial pressure of oxygen (PaO2) is as low as 70 mm Hg. Therefore, SpO2 may not provide advance warning of falling arterial oxygenation until PaO2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when SpO2 is >98%. This study evaluates the ORI to PaO2 relationship during surgery. ⋯ These findings suggest that ORI >0.24 can distinguish PaO2 ≥100 mm Hg when SpO2 is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish PaO2 ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling PaO2 approaching 100 mm Hg when SpO2 is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively.
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Anesthesia and analgesia · Sep 2016
The Effects of Vasopressin and Oxytocin on the Fetoplacental Distal Stem Arteriolar Vascular Resistance of the Dual-Perfused, Single, Isolated, Human Placental Cotyledon.
Vasoactive agents administered to counter maternal hypotension at cesarean delivery may theoretically intensify the hypoxemic fetoplacental vasoconstrictor response and, hence, negatively impact transplacental oxygen delivery to the fetus. Yet, this aspect of their pharmacodynamic profiles is seldom mentioned, let alone investigated. We hypothesized that vasopressin, a potent systemic vasoconstrictor, and oxytocin, a uterotonic agent administered routinely at cesarean delivery, which, in contrast to vasopressin, possesses significant systemic vasodilator properties, would not influence distal stem villous arteriolar resistance. ⋯ Oxytocin and vasopressin do not influence human fetoplacental distal stem villous arteriolar resistance. The neutral impact of vasopressin noted here is thus analogous to the reported negligible influence of the drug on human pulmonary arteriolar resistance. Neither drug seems likely to adversely influence the compensatory hypoxemic fetoplacental vasoconstrictor response.
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Anesthesia and analgesia · Sep 2016
Arginase Inhibition Reverses Endothelial Dysfunction, Pulmonary Hypertension, and Vascular Stiffness in Transgenic Sickle Cell Mice.
In sickle cell disease (SCD), hemolysis results in the release and activation of arginase, an enzyme that reciprocally regulates nitric oxide (NO) synthase activity and thus, NO production. Simply supplementing the common substrate L-arginine, however, fails to improve NO bioavailability. In this study, we tested the hypothesis that arginase inhibition would improve NO bioavailability and thereby attenuate systemic and pulmonary vascular endothelial dysfunction in transgenic mice with SCD. ⋯ Arginase inhibition improves NO bioavailability and thereby attenuates systemic and pulmonary vascular endothelial dysfunction in transgenic mice with SCD. Therefore, arginase is a potential therapeutic target in the treatment of cardiovascular dysfunction in SCD.