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Biomedical subjects

Carol L Wagner

Publications and source records attributed to Carol L Wagner.

At least 19 recordsLinked to original sources
PubMed2007

Circulating vitamin D3 and 25-hydroxyvitamin D in humans: An important tool to define adequate nutritional vitamin D status.

Circulating 25-hydroxyvitamin D [25(OH)D] is generally considered the means by which we define nutritional vitamin D status. There is much debate, however, with respect to what a healthy minimum level of circulation 25(OH)D should be. Recent data using various biomarkers such as intact parathyroid hormone (PTH), intestinal calcium absorption, and skeletal density measurements suggest this minimum level to be 80 nmol (32 ng/mL). Surprisingly, the relationship between circulating vitamin D(3) and its metabolic product-25(OH)D(3) has not been studied. We investigated this relationship in two separate populations: the first, individuals from Hawaii who received significant sun exposure; the second, subjects from a lactation study who received up to 6400IU vitamin D(3)/day for 6 months. Results (1) the relationship between circulating vitamin D(3) and 25(OH)D in both groups was not linear, but appeared saturable and controlled; (2) optimal nutritional vitamin D status appeared to occur when molar ratios of circulating vitamin D(3) and 25(OH)D exceeded 0.3; at this point, the V(max) of the 25-hydroxylase appeared to be achieved. This was achieved when circulating 25(OH)D exceeded 100 nmol. We hypothesize that as humans live today, the 25-hydroxylase operates well below its V(max) because of chronic substrate deficiency, namely vitamin D(3). When humans are sun (or dietary) replete, the vitamin D endocrine system will function in a fashion as do these other steroid synthetic pathways, not limited by substrate. Thus, the relationship between circulating vitamin D and 25(OH)D may represent what "normal" vitamin D status should be.

Cholecalciferol↗
PubMed2006

Parameter selection for and implementation of a web-based decision-support tool to predict extubation outcome in premature infants.

BACKGROUND: Approximately 30% of intubated preterm infants with respiratory distress syndrome (RDS) will fail attempted extubation, requiring reintubation and mechanical ventilation. Although ventilator technology and monitoring of premature infants have improved over time, optimal extubation remains challenging. Furthermore, extubation decisions for premature infants require complex informational processing, techniques implicitly learned through clinical practice. Computer-aided decision-support tools would benefit inexperienced clinicians, especially during peak neonatal intensive care unit (NICU) census. METHODS: A five-step procedure was developed to identify predictive variables. Clinical expert (CE) thought processes comprised one model. Variables from that model were used to develop two mathematical models for the decision-support tool: an artificial neural network (ANN) and a multivariate logistic regression model (MLR). The ranking of the variables in the three models was compared using the Wilcoxon Signed Rank Test. The best performing model was used in a web-based decision-support tool with a user interface implemented in Hypertext Markup Language (HTML) and the mathematical model employing the ANN. RESULTS: CEs identified 51 potentially predictive variables for extubation decisions for an infant on mechanical ventilation. Comparisons of the three models showed a significant difference between the ANN and the CE (p = 0.0006). Of the original 51 potentially predictive variables, the 13 most predictive variables were used to develop an ANN as a web-based decision-tool. The ANN processes user-provided data and returns the prediction 0-1 score and a novelty index. The user then selects the most appropriate threshold for categorizing the prediction as a success or failure. Furthermore, the novelty index, indicating the similarity of the test case to the training case, allows the user to assess the confidence level of the prediction with regard to how much the new data differ from the data originally used for the development of the prediction tool. CONCLUSION: State-of-the-art, machine-learning methods can be employed for the development of sophisticated tools to aid clinicians' decisions. We identified numerous variables considered relevant for extubation decisions for mechanically ventilated premature infants with RDS. We then developed a web-based decision-support tool for clinicians which can be made widely available and potentially improve patient care world wide.

Birth Weight↗
PubMed2006

The role of personality and other factors in a mother's decision to initiate breastfeeding.

The objective of the study was to measure the impact of personality and other factors on the decision to initiate breastfeeding. Mothers were enrolled (24-96 hours postpartum) and were classified as fully breastfeeding, formula-feeding, or combination-feeding. A semi-structured interview about maternal sociodemographics and attitudes and a standardized personality inventory (NEO-PI-R) were conducted. Eighty-seven mothers completed the study: 50 breastfeeders, 6 combination feeders, and 31 formula feeders. Because of small numbers, combination-feeder mothers (n = 6) were excluded from analyses. Maternal age, marriage, ethnicity, and socioeconomic status were significantly associated with breastfeeding. Breastfeeding and formula-feeding groups differed on 3 personality domains: extraversion (53.3 breastfeeding vs 46.9 formula-feeding, P = .002), openness (51.6 vs 46.2, P = .008), and agreeableness (48.5 vs 41.5, P = .01). In a multiple variable logistic regression model, extraversion (P = .03) and openness (P = .003) remained significant. Sociodemographics, experiential factors, and specific personality characteristics of mother were independently associated with maternal feeding decision.

Adult↗
PubMed2005

Moderate hypothermia in neonatal encephalopathy: efficacy outcomes.

Therapeutic hypothermia holds promise as a rescue neuroprotective strategy for hypoxic-ischemic injury, but the incidence of severe neurologic sequelae with hypothermia is unknown in encephalopathic neonates who present shortly after birth. This study reports a multicenter, randomized, controlled, pilot trial of moderate systemic hypothermia (33 degrees C) vs normothermia (37 degrees C) for 48 hours in neonates initiated within 6 hours of birth or hypoxic-ischemic event. The trial tested the ability to initiate systemic hypothermia in outlying hospitals and participating tertiary care centers, and determined the incidence of adverse neurologic outcomes of death and developmental scores at 12 months by Bayley II or Vineland tests between normothermic and hypothermic groups. Thirty-two hypothermic and 33 normothermic neonates were enrolled. The entry criteria selected a severely affected group of neonates, with 77% Sarnat stage III. Ten hypothermia (10/32, 31%) and 14 normothermia (14/33, 42%) patients expired. Controlling for treatment group, outborn infants were significantly more likely to die than hypoxic-ischemic infants born in participating tertiary care centers (odds ratio 10.7, 95% confidence interval 1.3-90). Severely abnormal motor scores (Psychomotor Development Index < 70) were recorded in 64% of normothermia patients and in 24% of hypothermia patients. The combined outcome of death or severe motor scores yielded fewer bad outcomes in the hypothermia group (52%) than the normothermia group (84%) (P = 0.019). Although these results need to be validated in a large clinical trial, this pilot trial provides important data for clinical trial design of hypothermia treatment in neonatal hypoxic-ischemic injury.

Child Development↗
PubMed2005

Moderate hypothermia in neonatal encephalopathy: safety outcomes.

Hypoxic-ischemic injury may cause multisystem organ damage with significant aberrations in clotting, renal, and cardiac functions. Systemic hypothermia may aggravate these medical conditions, such as bradycardia and increased clotting times, and very little safety data in neonatal hypoxic-ischemic injury is available. This study reports a multicenter, randomized, controlled pilot trial of moderate systemic hypothermia (33 degrees C) vs normothermia (37 degrees C) for 48 hours in infants with neonatal encephalopathy instituted within 6 hours of birth or hypoxic-ischemic event. The best outcome measures of safety were determined, comparing rates of adverse events between normothermia and hypothermia groups. A total of 32 hypothermia and 33 normothermia neonates were enrolled in seven centers. Adverse events and serious adverse effects were collected by the study team during the hospital admission, monitored by an independent study monitor, and reported to Institutional Review Boards and the Data and Safety Monitoring Committee. The following adverse events were observed significantly more commonly in the hypothermia group: more frequent bradycardia and lower heart rates during the period of hypothermia, longer dependence on pressors, higher prothrombin times, and lower platelet counts with more patients requiring plasma and platelet transfusions. Seizures as an adverse event were more common in the hypothermia group. These observed side effects of 48 hours of moderate systemic hypothermia were of mild to moderate severity and manageable with minor interventions.

Acidosis↗
PubMed2005

Changing a diagnosis: the importance of neonatal autopsy.

In this review of a clinical case and the subsequent autopsy findings, the importance of autopsy in determining the cause of death is highlighted. The importance of an autopsy in the neonatal age group is especially important since the yield of unexpected findings is considerably greater than in other groups, and the information may prove invaluable for parents and families in planning other pregnancies.

Autopsy↗
PubMed2004

Predicting extubation outcome in preterm newborns: a comparison of neural networks with clinical expertise and statistical modeling.

Even though ventilator technology and monitoring of premature infants has improved immensely over the past decades, there are still no standards for weaning and determining optimal extubation time for those infants. Approximately 30% of intubated preterm infants will fail attempted extubation, requiring reintubation and resuming of mechanical ventilation. A machine-learning approach using artificial neural networks (ANNs) to aid in extubation decision making is hereby proposed. Using expert opinion, 51 variables were identified as being relevant for the decision of whether to extubate an infant who is on mechanical ventilation. The data on 183 premature infants, born between 1999 and 2002, were collected by review of medical charts. The ANN extubation model was compared with alternative statistical modeling using multivariate logistic regression and also with the clinician's own predictive insight using sensitivity analysis and receiver operating characteristic curves. The optimal ANN model used 13 parameters and achieved an area under the receiver operating characteristic curve of 0.87 (out-of-sample validation), comparing favorably with multivariate logistic regression. It also compared well with the clinician's expertise, which raises the possibility of being useful as an automated alert tool. Because an ANN learns directly from previous data obtained in the institution where it is to be used, this makes it particularly amenable for application to evidence-based medicine. Given the variety of practices and equipment being used in different hospitals, this may be particularly relevant in the context of caring for preterm newborns who are on mechanical ventilation.

Decision Making↗
PubMed2004

Assessment of dietary vitamin D requirements during pregnancy and lactation.

Concerns about vitamin D have resurfaced in medical and scientific literature because the prevalence of vitamin D deficiency in the United States, particularly among darkly pigmented persons, has increased. The primary goals of this review were to discuss past and current literature and to reassess the dietary reference intake for vitamin D in adults, with particular focus on women during pregnancy and lactation. The appropriate dose of vitamin D during pregnancy and lactation is unknown, although it appears to be greater than the current dietary reference intake of 200-400 IU/d (5-10 microg/d). Doses of < or =10 000 IU vitamin D/d (250 microg/d) for up to 5 mo do not elevate circulating 25-hydroxyvitamin D to concentrations > 90 ng/mL, whereas doses < 1000 IU/d appear, in many cases, to be inadequate for maintaining normal circulating 25-hydroxyvitamin D concentrations of between 15 and 80 ng/mL. Vitamin D plays no etiologic role in cardiac valvular disease, such as that observed in Williams syndrome, and, as such, animal models involving vitamin D intoxication that show an effect on cardiac disease are flawed and offer no insight into normal human physiology. Higher doses of vitamin D are necessary for a large segment of Americans to achieve concentrations equivalent to those in persons who live and work in sun-rich environments. Further studies are necessary to determine optimal vitamin D intakes for pregnant and lactating women as a function of latitude and race.

Adult↗
PubMed2004

Vitamin D requirements during lactation: high-dose maternal supplementation as therapy to prevent hypovitaminosis D for both the mother and the nursing infant.

Scientific data pertaining to vitamin D supplementation during lactation are scarce. The daily recommended intake for vitamin D during lactation has been arbitrarily set at 400 IU/d (10 microg/d). This recommendation is irrelevant with respect to maintaining the nutritional vitamin D status of mothers and nursing infants, especially among darkly pigmented individuals. Our objective was to examine the effect of high-dose maternal vitamin D2 supplementation on the nutritional vitamin D status of mothers and nursing infants. Fully lactating women (n = 18) were enrolled at 1 mo after birth to 1 of 2 treatment arms, ie, 1600 IU vitamin D2 and 400 IU vitamin D3 (prenatal vitamin) or 3600 IU vitamin D2 and 400 IU vitamin D3, for a 3-mo study period. High-dose (1600 or 3600 IU/d) vitamin D2 supplementation for a period of 3 mo safely increased circulating 25-hydroxyvitamin D [25(OH)D] concentrations for both groups. The antirachitic activity of milk from mothers receiving 2000 IU/d vitamin D increased by 34.2 IU/L, on average, whereas the activity in the 4000 IU/d group increased by 94.2 IU/L. Nursing infant circulating 25(OH)D2 concentrations reflected maternal intake and the amount contained in the milk. With limited sun exposure, an intake of 400 IU/d vitamin D would not sustain circulating 25(OH)D concentrations and thus would supply only limited amounts of vitamin D to nursing infants in breast milk. A maternal intake of 2000 IU/d vitamin D would elevate circulating 25(OH)D concentrations for both mothers and nursing infants, albeit with limited capacity, especially with respect to nursing infants. A maternal intake of 4000 IU/d could achieve substantial progress toward improving both maternal and neonatal nutritional vitamin D status.

Adult↗
PubMed2003

Nutrition in the neonatal intensive care unit: how do we reduce the incidence of extrauterine growth restriction?

Extrauterine growth restriction is a major clinical problem for prematurely born neonates, especially critically ill preterm neonates, and malnutrition in the neonatal intensive-care unit remains common. There are numerous perceived risks to initiation of adequate nutritional support. How many of these factors pose a real risk to health outcomes is less clear. Current nutritional support does not prevent extrauterine growth restriction and the consequences of malnutrition are both acute and delayed. Our clinical approach to providing nutritional support impacts neonatal morbidity and long-term neuro developmental outcomes. While more and better evidence is needed to help guide best practices, this gap should not prevent neonatologists from using the observations in this review to improve their current practice. There is evidence that changes in nutritional support can have a positive influence on growth. These include early administration of intravenous amino acids and lipids, minimal enteral nutrition, and supplemented formula and human milk. Simply recognizing the degree of growth failure by monitoring weight and focusing on the accruing deficit should encourage clinicians to increase nutritional support to enhance recovery growth. Continued research is needed to define the efficiency of early feeding, more rapid advancements in nutritional support, protein needs, the optimal composition of breast-milk supplements, the etiology of necrotizing enterocolitis, and perhaps most importantly, the health consequences of extrauterine growth restriction.

Growth Disorders↗
PubMed2003

Web-based prediction of extubation outcome in premature infants on mechanical ventilation using an artificial neural network.

The web-based implementation of a decision-support tool for the prediction of extubation outcome in mechanically ventilated premature infants enables the integration of advanced and computationally intensive modeling approaches with easy-usage, no maintenance requirements and wide availability. Accordingly, the artificial neural network predictive tool developed provides decision-support in determining whether to extubate a premature infant to clinicians in NICUs anywhere with access to the Internet.

Decision Making, Computer-Assisted↗