Biomedical subjects

Francesca Bonati

Publications and source records attributed to Francesca Bonati.

3 recordsLinked to original sources

PubMed2004

Amnioreduction.

Pregnancies complicated by hydramnios are at increased risk of both maternal and fetal complications. Since amniotic pressure is elevated in polyhydramnios, it has been suggested that the complications may be mediated by anomalies connected with amniotic pressure. The rationale behind amnioreduction is thus to restore normal amniotic pressure by draining a large amount of amniotic fluid volume in order to reduce maternal discomfort, improve uteroplacental perfusion, and prolong pregnancy by limiting the risk of preterm labour and rupture of the membranes. The procedure has a complication rate in terms of spontaneous premature rupture of membranes, abruptio placenta, or chorioamnionitis, regardless of the technique adopted.

Drainage↗

PubMed2002

Ex vivo testing of a temperature- and pressure-controlled amnio-irrigator for fetoscopic surgery.

BACKGROUND: Currently, amnioinfusion fluids used in operative fetoscopy usually are preheated to body temperature. As the complexity of procedures increases, purposed designed devices should be designed that allow control of pressure and temperature during amnioinfusion or amnioexchange. In the current study, a prototype amnio-irrigator and fluid heater were evaluated. METHODS: The medical fluid heater heats fluid by conduction up to 37 degrees C. The maximum irrigation pressure and flow rates can be preset. Actual irrigation pressure (0 to 30 mm Hg) and flow rate (0 to 300 mL/min) can be read on the front panel. A series of ex vivo experiments were set up to determine the relationship between the flow rate (FR) and lumen of the instruments as well as the maximum flow rate (MFR) with and without the pressure control. Further, the relationship between FR and the irrigation pressure (IP) was determined. In an artificial pseudoamniotic sac the relationship between FR and change in temperature was measured, with and without the use of the medical fluid heater. RESULTS: When the IP was limited to 24 mm Hg, FR and pressure were correlated (r = 0.34; P <.001). The larger the functional lumen of the fetoscopic instrumentation, the higher the flow (r = 0.43; P <.001) and the lower the increase in IP (r = -0.47; P <.001). A quadratic relation between flow and temperature was observed both for preheated fluid as when using the fluid heater (r(2) = 0.71 and r(2) = 0.88; P <.001). However, at low flow rates, a thermal decrease of over 3 degrees C was observed when the fluid heater was not used. CONCLUSIONS: The current study quantifies an expected relationship between the diameter of the irrigation channel and achievable flow rates. It also shows that a medical fluid heater is needed when strict control of temperature would be desired.

Equipment Design↗

PubMed2002

Nitrous oxide amniodistention compared with fluid amniodistention reduces operation time while inducing no changes in fetal acid-base status in a sheep model for endoscopic fetal surgery.

OBJECTIVE: Our purpose was to evaluate in a sheep model for endoscopic fetal surgery the impact of nitrous oxide-gas amniodistention compared with fluid amniodistention on duration of surgery, hemorrhagic events, and fetomaternal acid-base status. STUDY DESIGN: Pregnant ewes (n = 16) at 92 to 104 days of gestation (term, 145 days) underwent amniodistention with Hartmann's solution (group I, n = 8) or nitrous oxide (group II, n = 8) at 38 degrees C. Endoscopic tracheal clipping according to a standardized surgical protocol was performed in all animals. The duration of fetoscopy (from insertion of first cannula until removal of last one), fetal surgery (fetal skin incision to skin closure), and number of bleeding episodes was recorded. Maternal and fetal blood gas values (pH, PO2, and PCO2) were measured at baseline and every 15 minutes during the experiment. Videotapes of the operations were assessed independently and scored by a visual analog scale in terms of smoothness of the operation and control of hemorrhagic events. RESULTS: Mean duration of fetoscopy (+/-SEM) (68 +/- 16 minutes vs 92 +/- 23 minutes) and fetal surgery (19 +/- 6 minutes vs 42 +/- 18 minutes) as well as number of bleeding episodes (1.9 +/- 0.8 minutes vs 5.8 +/- 2.1 minutes) was significantly reduced in animals operated with use of nitrous oxide amniodistention. In both groups, fetal and maternal blood gases remained unchanged during the entire experiment. Visual analog scale (VAS) scores were significantly higher for procedures conducted with use of gas distention. CONCLUSION: In a lamb model for fetal surgery, gas amniodistention with use of nitrous oxide results in a quicker operation procedure with less bleeding compared with fluid amniodistention, and without adverse side effects on fetomaternal acid-base status.

Acid-Base Equilibrium↗