Stacy Zamudio

National evaluation of healthcare provider attitudes toward organ donation after cardiac death

Objective:Organ donation after cardiac death will save lives by increasing the number of transplantable organs. But many healthcare providers are reluctant to participate when the withdrawal of intensive care leads to organ donation. Prior surveys indicate ethical concerns as a barrier to the practice of organ donation after cardiac death, but the specific issues that characterize these concerns are unknown. We thus aimed to identify what barriers healthcare providers perceive. Design:We conducted a qualitative analysis of focus group transcripts to identify issues of broad importance. Setting:Healthcare setting. Participants:Participants included 141 healthcare providers representing critical care and perioperative nurses, transplant surgeons, medical examiners, organ procurement personnel, neurosurgeons, and neurologists. Interventions:Collection and analysis of information regarding healthcare providers’ attitudes and beliefs. Measurements and Main Results:All focus groups agreed that increased organ availability is a benefit but questioned the quality of organs recovered. Study participants identified a lack of standards for patient prognostication and cardiopulmonary death and a failure to prevent a conflict between patient and donor interests as obstacles to acceptance of organ donation after cardiac death. They questioned the practices and motives of colleagues who participate in organ donation after cardiac death, apprehensive that real or perceived impropriety would affect public perception. Conclusions:Healthcare providers are uncomfortable at the clinical juncture where end-of-life care and organ donation interface. Our findings are consistent with theories that care providers are hesitant to perform medical tasks that they consider to be outside the focus of their practice, especially when there is potential conflict of interest. This conflict appears to impose moral distress on healthcare providers and limits acceptance of organ donation after cardiac death. Future research is warranted to examine the effect of standardized procedures on reducing moral distress. The hypothesis generated by this qualitative study is that use of neutral third parties to broach the subject of organ donation may improve acceptance of organ donation after cardiac death.

Hypoglycemia and the Origin of Hypoxia-Induced Reduction in Human Fetal Growth

Background The most well known reproductive consequence of residence at high altitude (HA >2700 m) is reduction in fetal growth. Reduced fetoplacental oxygenation is an underlying cause of pregnancy pathologies, including intrauterine growth restriction and preeclampsia, which are more common at HA. Therefore, altitude is a natural experimental model to study the etiology of pregnancy pathophysiologies. We have shown that the proximate cause of decreased fetal growth is not reduced oxygen availability, delivery, or consumption. We therefore asked whether glucose, the primary substrate for fetal growth, might be decreased and/or whether altered fetoplacental glucose metabolism might account for reduced fetal growth at HA. Methods Doppler and ultrasound were used to measure maternal uterine and fetal umbilical blood flows in 69 and 58 residents of 400 vs 3600 m. Arterial and venous blood samples from mother and fetus were collected at elective cesarean delivery and analyzed for glucose, lactate and insulin. Maternal delivery and fetal uptakes for oxygen and glucose were calculated. Principal Findings The maternal arterial – venous glucose concentration difference was greater at HA. However, umbilical venous and arterial glucose concentrations were markedly decreased, resulting in lower glucose delivery at 3600 m. Fetal glucose consumption was reduced by >28%, but strongly correlated with glucose delivery, highlighting the relevance of glucose concentration to fetal uptake. At altitude, fetal lactate levels were increased, insulin concentrations decreased, and the expression of GLUT1 glucose transporter protein in the placental basal membrane was reduced. Conclusion/Significance Our results support that preferential anaerobic consumption of glucose by the placenta at high altitude spares oxygen for fetal use, but limits glucose availability for fetal growth. Thus reduced fetal growth at high altitude is associated with fetal hypoglycemia, hypoinsulinemia and a trend towards lactacidemia. Our data support that placentally-mediated reduction in glucose transport is an initiating factor for reduced fetal growth under conditions of chronic hypoxemia.

Where the O2 goes to: preservation of human fetal oxygen delivery and consumption at high altitude

Fetal growth is decreased at high altitude (> 2700 m). We hypothesized that variation in fetal O2 delivery might account for both the altitude effect and the relative preservation of fetal growth in multigenerational natives to high altitude. Participants were 168 women of European or Andean ancestry living at 3600 m or 400 m. Ancestry was genetically confirmed. Umbilical vein blood flow was measured using ultrasound and Doppler. Cord blood samples permitted calculation of fetal O2 delivery and consumption. Andean fetuses had greater blood flow and oxygen delivery than Europeans and weighed more at birth, regardless of altitude (+208 g, P < 0.0001). Fetal blood flow was decreased at 3600 m (P < 0.0001); the decrement was similar in both ancestry groups. Altitude‐associated decrease in birth weight was greater in Europeans (−417 g) than Andeans (−228 g, P < 0.005). Birth weight at 3600 m was > 200 g lower for Europeans at any given level of blood flow or O2 delivery. Fetal haemoglobin concentration was increased, decreased, and the fetal / curve was left‐shifted at 3600 m. Fetuses receiving less O2 extracted more (r2= 0.35, P < 0.0001). These adaptations resulted in similar fetal O2 delivery and consumption across all four groups. Increased umbilical venous O2 delivery correlated with increased fetal O2 consumption per kg weight (r2= 0.50, P < 0.0001). Blood flow (r2= 0.16, P < 0.001) and O2 delivery (r2= 0.17, P < 0.001) correlated with birth weight at 3600 m, but not at 400 m (r2= 0.04, and 0.03, respectively). We concluded that the most pronounced difference at high altitude is reduced fetal blood flow, but fetal haematological adaptation and fetal capacity to increase O2 extraction indicates that deficit in fetal oxygen delivery is unlikely to be causally associated with the altitude‐ and ancestry‐related differences in fetal growth.

Maternal oxygen delivery is not related to altitude- and ancestry-associated differences in human fetal growth.

Fetal growth is reduced at high altitude, but the decrease is less among long‐resident populations. We hypothesized that greater maternal uteroplacental O2 delivery would explain increased fetal growth in Andean natives versus European migrants to high altitude. O2 delivery was measured with ultrasound, Doppler and haematological techniques. Participants (n= 180) were pregnant women of self‐professed European or Andean ancestry living at 3600 m or 400 m in Bolivia. Ancestry was quantified using ancestry‐informative single nucleotide polymorphims. The altitude‐associated decrement in birth weight was 418 g in European versus 236 g in Andean women (P < 0.005). Altitude was associated with decreased uterine artery diameter, volumetric blood flow and O2 delivery regardless of ancestry. But the hypothesis was rejected as O2 delivery was similar between ancestry groups at their respective altitudes of residence. Instead, Andean neonates were larger and heavier per unit of O2 delivery, regardless of altitude (P < 0.001). European admixture among Andeans was negatively correlated with birth weight at both altitudes (P < 0.01), but admixture was not related to any of the O2 transport variables. Genetically mediated differences in maternal O2 delivery are thus unlikely to explain the Andean advantage in fetal growth. Of the other independent variables, only placental weight and gestational age explained significant variation in birth weight. Thus greater placental efficiency in O2 and nutrient transport, and/or greater fetal efficiency in substrate utilization may contribute to ancestry‐ and altitude‐related differences in fetal growth. Uterine artery O2 delivery in these pregnancies was 99 ± 3 ml min−1, ∼5‐fold greater than near‐term fetal O2 consumption. Deficits in maternal O2 transport in third trimester normal pregnancy are unlikely to be causally associated with variation in fetal growth.

Placental metabolic reprogramming: do changes in the mix of energy-generating substrates modulate fetal growth?

Insufficient oxygen leads to the cessation of growth in favor of cellular survival. Our unique model of high-altitude human pregnancy indicates that hypoxia-induced reductions in fetal growth occur at higher levels of oxygen than previously described. Fetal PO(2) is surprisingly high and fetal oxygen consumption unaffected by high altitude, whereas fetal glucose delivery and consumption decrease. Placental delivery of energy-generating substrates to the fetus is thus altered by mild hypoxia, resulting in maintained fetal oxygenation but a relative fetal hypoglycemia. Our data point to this altered mix of substrates as a potential initiating factor in reduced fetal growth, since oxygen delivery is adequate. These data support the existence, in the placenta, of metabolic reprogramming mechanisms, previously documented in tumor cells, whereby HIF-1 stimulates reductions in mitochondrial oxygen consumption at the cost of increased glucose consumption. Decreased oxygen consumption is not due to substrate (oxygen) limitation but rather results from active inhibition of mitochondrial oxygen utilization. We suggest that under hypoxic conditions, metabolic reprogramming in the placenta decreases mitochondrial oxygen consumption and increases anerobic glucose consumption, altering the mix of energy-generating substrates available for transfer to the fetus. Increased oxygen is available to support the fetus, but at the cost of less glucose availability, leading to a hypoglycemia-mediated decrease in fetal growth. Our data suggest that metabolic reprogramming may be an initiating step in the progression to more severe forms of fetal growth restriction and points to the placenta as the pivotal source of fetal programming in response to an adverse intrauterine environment.

Maternal and Fetal Outcomes in Placenta Accreta After Institution of Team-Managed Care:

Introduction: Placenta accreta significantly contributes to maternal morbidity and mortality. We evaluated whether planned delivery and experienced, team-managed surgical intervention results in improved outcomes. We also examined whether risk factors differed for accreta, increta, and percreta and evaluated whether excess lower segment uterine vascularity correlates with disease severity. Methods: We retrospectively analyzed patients before versus after institution of a management protocol. Of the 58 044 deliveries over 10 years, there were 67 women whose pregnancies were histopathologically confirmed as placenta accreta, increta, or percreta (1/866). Clinical outcome measures were estimated blood loss (EBL), packed red blood cells (pRBCs) transfused, maternal and fetal complications, intensive care unit admission, and length of stay. Results: There were no maternal or infant deaths. In the managed cohort, EBL was reduced by 48% (P < .001), intraoperative pRBCs transfused by 40% (P < .01), total transfused pRBCs per case by 50% (P < .01), and surgical intensive care unit admissions by >50% (P < .01). Assessment of maternal risk factors by diagnosis revealed marked differences between accreta versus increta and percreta. Clinically assessed excess vascularity of the lower uterine segment correlated with disease severity. The incidence of neonatal complications was similar in both cohorts. Conclusions: Targeted delivery at 34 weeks and team-managed diagnosis, treatment, and care of patients with placenta accreta were associated with improved maternal, but not neonatal outcomes.

Three-Dimensional Power Doppler Ultrasonography for Diagnosing Abnormally Invasive Placenta and Quantifying the Risk.

OBJECTIVE: To test an objective ultrasound marker for diagnosing the presence and severity of abnormally invasive placenta. METHODS: Women at risk of abnormally invasive placenta underwent a three-dimensional power Doppler ultrasound scan. The volumes were examined offline by a blinded observer. The largest area of confluent three-dimensional power Doppler signal (Area of Confluence [Acon], cm2) at the uteroplacental interface was measured and compared in women subsequently diagnosed with abnormally invasive placenta and women in a control group who did not have abnormally invasive placenta. Receiver operating characteristic curves were plotted for prediction of abnormally invasive placenta and abnormally invasive placenta requiring cesarean hysterectomy. RESULTS: Ninety-three women were recruited. Results were available for 89. Abnormally invasive placenta was clinically diagnosed in 42 women; 36 required hysterectomy and had abnormally invasive placenta confirmed histopathologically. Median and interquartile range for Acon was greater for abnormally invasive placenta (44.2 [31.4–61.7] cm2) compared with women in the control group (4.5 cm2 [2.9–6.6], P<.001) and even greater in the 36 requiring hysterectomy (46.6 cm2 [37.2–72.6], P<.001). Acon rose with histopathologic diagnosis: focal accreta (32.2 cm2 [17.2–57.3]), accreta (59.6 cm2 [40.1–89.9]), and percreta (46.6 cm2 [37.5–71.5]; P<.001 analysis of variance for linear trend). Receiver operating characteristic analysis for prediction of abnormally invasive placenta revealed that with an Acon of 12.4 cm2 or greater, 100% sensitivity (95% confidence interval [CI] 91.6–100) could be obtained with 92% specificity (95% CI 79.6–97.6); area under the curve is 0.99 (95% CI 0.94–1.0). For prediction of abnormally invasive placenta requiring hysterectomy, 100% sensitivity (95% CI 90.3–100) can be obtained with an Acon of 17.4 cm2 or greater with 87% specificity (95% CI 74.7–94.5; area under the curve 0.98 [0.93–1.0]). CONCLUSION: The marker Acon provides a quantitative means for diagnosing abnormally invasive placenta and assessing severity. If further validated, subjectivity could be eliminated from the diagnosis of abnormally invasive placenta. LEVEL OF EVIDENCE: II

Regulation of Human Trophoblast GLUT1 Glucose Transporter by Insulin-Like Growth Factor I (IGF-I)

Glucose transport to the fetus across the placenta takes place via glucose transporters in the opposing faces of the barrier layer, the microvillous and basal membranes of the syncytiotrophoblast. While basal membrane content of the GLUT1 glucose transporter appears to be the rate-limiting step in transplacental transport, the factors regulating transporter expression and activity are largely unknown. In view of the many studies showing an association between IGF-I and fetal growth, we investigated the effects of IGF-I on placental glucose transport and GLUT1 transporter expression. Treatment of BeWo choriocarcinoma cells with IGF-I increased cellular GLUT1 protein. There was increased basolateral (but not microvillous) uptake of glucose and increased transepithelial transport of glucose across the BeWo monolayer. Primary syncytial cells treated with IGF-I also demonstrated an increase in GLUT1 protein. Term placental explants treated with IGF-I showed an increase in syncytial basal membrane GLUT1 but microvillous membrane GLUT1 was not affected. The placental dual perfusion model was used to assess the effects of fetally perfused IGF-I on transplacental glucose transport and syncytial GLUT1 content. In control perfusions there was a decrease in transplacental glucose transport over the course of the perfusion, whereas in tissues perfused with IGF-I through the fetal circulation there was no change. Syncytial basal membranes from IGF-I perfused tissues showed an increase in GLUT1 content. These results demonstrate that IGF-I, whether acting via microvillous or basal membrane receptors, increases the basal membrane content of GLUT1 and up-regulates basal membrane transport of glucose, leading to increased transepithelial glucose transport. These observations provide a partial explanation for the mechanism by which IGF-I controls nutrient supply in the regulation of fetal growth.

IFPA Meeting 2010 Workshops Report II: Placental pathology; trophoblast invasion; fetal sex; parasites and the placenta; decidua and embryonic or fetal loss; trophoblast differentiation and syncytialisation

Workshops are an important part of the IFPA annual meeting. At IFPA Meeting 2010 diverse topics were discussed in twelve themed workshops, six of which are summarized in this report. 1. The placental pathology workshop focused on clinical correlates of placenta accreta/percreta. 2. Mechanisms of regulation of trophoblast invasion and spiral artery remodeling were discussed in the trophoblast invasion workshop. 3. The fetal sex and intrauterine stress workshop explored recent work on placental sex differences and discussed them in the context of whether boys live dangerously in the womb.4. The workshop on parasites addressed inflammatory responses as a sign of interaction between placental tissue and parasites. 5. The decidua and embryonic/fetal loss workshop focused on key regulatory mediators in the decidua, embryo and fetus and how alterations in expression may contribute to different diseases and adverse conditions of pregnancy. 6. The trophoblast differentiation and syncytialisation workshop addressed the regulation of villous cytotrophoblast differentiation and how variations may lead to placental dysfunction and pregnancy complications.

Differentiation of first trimester cytotrophoblast to extravillous trophoblast involves an epithelial–mesenchymal transition

The transformation of cytotrophoblast (CTB) to extravillous trophoblast (EVT) is an essential process for placental implantation. EVT generated at the tips of the anchoring villi migrate away from the placenta and invade the endometrium and maternal spiral arteries, where they modulate maternal immune responses and remodel the arteries into high-volume conduits to facilitate uteroplacental blood flow. The process of EVT differentiation has several factors in common with the epithelial-to-mesenchymal transition (EMT) observed in embryonic development, wound healing and cancer metastasis. We hypothesized that the generation of invasive EVT from CTB was a form of EMT. We isolated paired CTB and EVT from first trimester placentae, and compared their gene expression using a PCR array comprising probes for genes involved in EMT. Out of 84 genes, 24 were down-regulated in EVT compared to CTB, including epithelial markers such as E-cadherin (-11-fold) and occludin (-75-fold). Another 30 genes were up-regulated in EVT compared to CTB including mesenchymal markers such as vimentin (235-fold) and fibronectin (107-fold) as well as the matrix metalloproteinases, MMP2 and MMP9 (357-fold, 129-fold). These alterations also included major increases in the ZEB2 (zinc finger E-box binding homeobox 2, 198-fold) and TCF4 (transcription factor 4, 18-fold) transcription factors, suggesting possible stimulatory mechanisms. There was substantial up-regulation of the genes encoding TGFβ1 and TGFβ2 (48-fold, 115-fold), which may contribute to the maintenance of the mesenchymal-like phenotype. We conclude that transformation of CTB to EVT is consistent with an EMT, although the differences with other types of EMT suggest this may be a unique form.