LOS ANGELES (May 3, 1999) -- Two studies conducted by Augusto Sola, Director of Neonatology, and Ruth and Harry Roman Chair of Neonatology at Cedars-Sinai Medical Center, and his associates are being published and made available at the Annual Meeting of the Pediatric Academic Societies in San Francisco this week.
"Tidal Volume Measurements in Neonates: Are They Reliable?" analyzes the Pulmonary Mechanics Monitoring (PMM) capability that has been incorporated into ventilator design. Because clinicians use these PMM systems to assist in ventilator management, accuracy and reliability are critical, but various systems differ in working principle and sensor location, depending on manufacturer.
This study of three manufacturers' ventilators was designed to determine if measured expiratory tidal volume (Vte) accurately reflected actual Tidal Volume (Vt). Tidal volume is the amount of air inhaled and exhaled during normal breathing. According to the results, expiratory tidal volume measurements varied markedly between ventilators: two overestimated and one understimated.
The second study for publication is titled "Neonatal Hypoglycemia: A Need for a New Definition?"
Although as many as 25 percent of newborns are screened for "low blood sugar," there is no agreement on what constitutes neonatal hypoglycemia (NH). The authors of the study set out to propose a new "working definition" of NH based on medical literature. In searching for medical evidence upon which to base this definition, they found no previously published studies based on randomized, controlled, large samples or randomized small samples. Therefore, they used "lower-quality" evidence.
Their new proposed working definition of neonatal hypoglycemia uses higher plasma glucose levels than the "historic definition" allowed but this definition may need to be adjusted as data from higher-grade and larger studies become available.
In addition to having these findings published, Dr. Sola participated in a Neonatal Immunology and Hematology session on Monday, May 3, serving as a member of a group panel regarding "Neonatal Transfusion Issues: Platelets, Erythrocytes, T-Cell Activation." The panel discussed the significant issue of reducing the number of transfusions in neonates.
Dr. Sola also participated in a poster-session exhibit Saturday, May 1, titled: "Nitric Oxide Levels and Its Metabolites in Term Fetal Circulation: Relation to the Presence of Labor."
Nitric oxide that naturally occurs in the feto-placental circulation and the uterus contributes to vascular and uterine functions during pregnancy and at the time of birth. Nitric oxide (NO) levels may decrease with advancing gestation but the levels at various gestational ages have not been documented. Also, while there may be an association between decreasing NO concentrations in the fetal circulation and the presence of labor, this connection has not been well established. Providing this information is the goal of this ongoing study.
To date, the NO concentrations of blood from the umbilical cords of 47 full-term infants have been analyzed. Findings indicate that nitric oxide production is indeed lower in the presence of labor. The authors speculate that a "nitric oxide production threshold" is related to the initiation of labor at term.
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