Anesthesiology
-
Multicenter Study Observational Study
End-tidal to Arterial Gradients and Alveolar Deadspace for Anesthetic Agents.
According to the "three-compartment" model of ventilation-perfusion ((Equation is included in full-text article.)) inequality, increased (Equation is included in full-text article.)scatter in the lung under general anesthesia is reflected in increased alveolar deadspace fraction (VDA/VA) customarily measured using end-tidal to arterial (A-a) partial pressure gradients for carbon dioxide. A-a gradients for anesthetic agents such as isoflurane are also significant but have been shown to be inconsistent with those for carbon dioxide under the three-compartment theory. The authors hypothesized that three-compartment VDA/VA calculated using partial pressures of four inhalational agents (VDA/VAG) is different from that calculated using carbon dioxide (VDA/VACO2) measurements, but similar to predictions from multicompartment models of physiologically realistic "log-normal" (Equation is included in full-text article.)distributions. ⋯ Alveolar deadspace for anesthetic agents is much larger than for carbon dioxide and related to blood solubility. Unlike the three-compartment model, multicompartment (Equation is included in full-text article.)scatter models explain this from physiologically realistic gas uptake distributions, but suggest a residual factor other than solubility, potentially diffusion limitation, contributes to deadspace.
-
Observational Study
Postoperative Hypotension after Noncardiac Surgery and the Association with Myocardial Injury.
Intraoperative hypotension has been associated with postoperative morbidity and early mortality. Postoperative hypotension, however, has been less studied. This study examines postoperative hypotension, hypothesizing that both the degree of hypotension severity and longer durations would be associated with myocardial injury. ⋯ In this study, postoperative hypotension was common and was independently associated with myocardial injury.