ABSTRACT
Mitral valve stenosis is often associated with increased pulmonary vascular resistance resulting in pulmonary hypertension, which may lead to or exacerbate right heart dysfunction. Hypocapnia is a known pulmonary vasodilator. The purpose of this study was to evaluate whether induced hypocapnia is an effective treatment for pulmonary hypertension following elective mitral valve replacement in adults. In a prospective, crossover controlled trial, 8 adult patients with mitral stenosis were studied in the intensive care unit following elective mitral valve replacement. Hypocapnia was induced by removal of previously added dead space. Normocapnic [baseline], hypocapnic and recovery hemodynamic parameters including cardiac output, pulmonary vascular resistance, pulmonary artery pressure and systemic oxygen delivery and consumption were recorded. Moderate hypocapnia [an end-tidal carbon dioxide concentration reduced to 28 +/- 5 mmHg] resulted in decreases in pulmonary vascular resistance and mean pulmonary artery pressure of 33% and 25%, respectively. Hypocapnia had no other hemodynamic or respiratory effects. The changes in pulmonary vascular resistance and mean pulmonary artery pressure were reversible. Moderate hypocapnia was effective in decreasing pulmonary vascular tone in adults following mitral valve replacement. The application of this maneuver in the immediate postoperative period may provide a bridge until pulmonary vascular tone begins to normalize following surgery
ABSTRACT
Some technical aspects of intraoperative anesthetic care of pediatric surgical patients are discussed. Recent concepts of premedicant, anesthetic and muscle relaxant drugs as related to the pediatric patient are presented. Endotracheal intubation is an integral part of the pediatric anesthetic management. Adequacy of fluid and blood replacement is emphasized. Most current pediatric anesthetic systems incorporate the "T piece" principle. Maintenance of a near normal PaCo2 could be accomplished by allowing partial rebreathing during controlled ventilation. Current status of three useful techniques is presented: deliberate hypotension, hemodilution, and the rapid induction-intubation technique for children with a full stomach. Anesthetic considerations of special problems, such as neurosurgery or cardiac surgery and monitoring, are not discussed