Positional effects on maternal cardiac output during labor with epidural analgesia.

OBJECTIVE: Our purpose was to test the hypothesis that the supine versus the lateral position is associated with a greater decrement in cardiac output after epidural analgesia in labor. STUDY DESIGN: Twenty-one normal term subjects were randomized to the left lateral or supine position in early labor. Cardiac output measured by the acetylene rebreathing method, stroke volume, heart rate, mean arterial pressure, and systemic vascular resistance were obtained at 5-minute intervals, beginning before a 500 ml intravenous fluid bolus (baseline) and ending 45 minutes after epidural injection. RESULTS: Mean baseline supine versus lateral group differences were significant for 21% lower cardiac output, 21% lower stroke volume, 19% higher mean arterial pressure, 50% higher systemic vascular resistance, and equivalent heart rate. In the supine group fluid bolus resulted in significantly increased cardiac output and stroke volume, decreased mean arterial pressure and systemic vascular resistance, and unchanged heart rate. In the supine group cardiac output and stroke volume decreased significantly after epidural injection. The lateral position group exhibited no hemodynamic alterations after fluid bolus or epidural. CONCLUSIONS: In contrast to the lateral position, the supine position is associated with a significant postepidural decrement in cardiac output, not identified by a change in heart rate. This likely reflects an inability to maintain stable preload volume in the supine position.

Precision of office-based blood glucose meters in screening for gestational diabetes.

OBJECTIVE: Is the precision of currently available glucose meters adequate for gestational diabetes screening? STUDY DESIGN: We performed a prospective cohort study of 62 gravid women and compared the precision of three glucose meters to laboratory standard technology. RESULTS: The HemoCue coefficient of variation was sufficiently low in venous whole blood and plasma and capillary whole blood and plasma (3.0%, 1.8%, 2.8%, and 2.3%, respectively) to allow use in gestational diabetes screening. The OneTouch II coefficient of variation was sufficiently low in capillary whole blood (2.7%) to allow use in gestational diabetes screening but was too high in venous whole blood and plasma and in capillary plasma (3.6%, 7.8%, and 5.7%). The ExacTech coefficient of variation was too high in venous or capillary whole blood (5.4% and 8.1%) for use in gestational diabetes screening and does not analyze plasma samples. CONCLUSION: The HemoCue meter in venous and capillary whole blood and plasma and the OneTouch II meter in capillary whole blood have coefficients of variation low enough for gestational diabetes screening.