RESUMO
BACKGROUND: Static cold storage is a mainstay of the heart transplantation (HTx) process. However, the temperature distribution within the organ at each stage of HTx is unknown. In this study, we aimed to quantify how long it took for the heart to warm up and cool down and the nature of temperature distribution with the organ at each stage of HTx. METHODS: We used high-fidelity computational time-varying biothermal modeling on an anatomical human heart model to model the HTx process in 5 interdependent stages, including cardioplegia, back-table preparation, static cold storage ice box storage and transport, back-table preparation at the recipient institution and warm-up within the recipient body before cross-clamp release. RESULTS: Results indicate that the heart experiences roller-coaster-like temperature changes in stage, including rapid cool down from body temperature to <10 °C within 15 min in stage 1 with a maximum cooling rate of 5 °C/min. This was followed by cooling and extended duration of temperatures <2 °C in the ice box and rapid warming up to body temperature within 10 min at rates of 2 °C/min and 4 °C/min for the left and right sides, respectively, during implantation. Temperature distribution throughout the heart was heterogeneous, with right-sided temperature change occurring nearly 2× faster than on the left side. CONCLUSIONS: We present, for the first time, detailed temperature distributions and evolution at each stage of HTx. Quantification of the rapid and heterogeneous temperature changes is crucial to optimize HTx and improve organ viability.
RESUMO
OBJECTIVES: To compare the efficacy of a single 100 micro g intramuscular (IM) carbetocin injection, a long-acting oxytocin agonist, to a 2-hour 10 IU oxytocin intravenous (IV) infusion, in reducing the incidence and severity of postpartum hemorrhage (PPH) in women at risk for this condition. METHODS: A randomized, double-blind, placebo-controlled study was conducted at 2 hospital centres, including 160 women with at least 1 risk factor for PPH. Eighty-three women received 100 microg carbetocin IM and an IV placebo immediately after placental delivery, while 77 women received placebo IM and oxytocin IV infusion. Complete blood count was collected at entry and 24 hours postpartum. All outcome measures, including the need for additional uterotonic agents or uterine massage, blood loss, and drop in hemoglobin and hematocrit, were analyzed using chi-square, Fisher exact, and Student t tests. RESULTS: Population profile and risk factors for PPH were similar for each group. No significant difference was observed in the number of women requiring additional uterotonic medication (12 in each group). However, in the carbetocin group, 36 of the 83 women (43.4%) required at least 1 uterine massage compared to 48 of the 77 women (62.3%) in the oxytocin group (P <.02). Overall, uterotonic intervention was clinically indicated in 37 of the women (44.6%) receiving carbetocin compared to 49 of the women (63.6%) given an IV oxytocin infusion (P <.02). There were no differences in laboratory PPH indicators between the 2 groups.