Experimental Study on Potential Heat Treatment Issues of Large Bi-2212 Coils.

The route to 30 T NMR endorsed by a recent National Academy report clearly still has many challenges to achieve high stability and homogeneous high temperature superconducting (HTS) magnet. As the only HTS conductor with round wire (RW) geometry, Bi2Sr2CaCu2O8-x (Bi-2212) RW conductor is very attractive for NMR magnet applications. At present, an NMR quality demonstration magnet with Bi-2212 RW wound insert coils is under development at the National High Magnetic Field Laboratory (NHMFL). The target of this demonstration magnet is to generate a total field of 23+ T with ppm level homogeneity. Since Bi-2212 coils require Wind-and-React (W&R) technology, our initial major concern was that large Bi-2212 coils might deform during the typical partial melt Bi-2212 heat treatment (HT) due to their large self-weight. To experimentally mimic the HT of large Bi-2212 coil, several small test coils were heat treated under deadweight loads. After 1 bar Bi-2212 full reaction, these coils were characterized in terms of coil geometry, transport critical current properties, oxygenation status and insulation performance. Coil geometry and individual wire shape was in fact not distorted, nor was transport properties degradation was induced by mechanical loading. Uniform oxygen equilibration was achieved in these coils even though they were coated with dense oxide insulation. However, although the TiO2-based insulation coating was well preserved on the wire surface, several coils developed electrical shorts.

Tensile properties and critical current strain limits of reinforced Bi-2212 conductors for high field magnets.

We study here the effect of axial strain on the degradation of the critical current Ic for bare and reinforced, overpressure processed Bi-2212 conductors. We show that reinforcement markedly improves the conductor's stress limit, doubling it from ~150 MPa in the bare conductor to ~300 MPa when reinforced. We find also that certain processes used to reinforce the conductor slightly reduce the Ic degradation strain limit from ~0.6% to ~0.4%. Stress vs strain data taken from the samples studied here has been used to create a finite element model to explore the feasibility of using a reinforced Bi-2212 strand (produced by Solid Material Solutions) in a small test coil. The model predicts an IC limited coil with a maximum hoop strain of 0.31%, well below the experimentally verified strain limit, and is designed to lead to Bi-2212 coils that are not strain limited, but Ic limited.

Real vs simulated umbilical cords for emergency umbilical catheterization training: a randomized crossover study.

OBJECTIVE: To measure performance, fidelity and preference of two emergency umbilical vessel catheter (eUVC) simulation models. STUDY DESIGN: A randomized crossover trial of senior pediatric residents randomized to place an eUVC first using a real cord (RC) or simulated cord (SC), and then place an eUVC using the other model. The eUVC placement times were recorded and analyzed. Subjects rated physical and functional fidelity and preference for each model. RESULTS: The eUVC placement time (mean±s.d. s) was slower in RC vs SC (153 s ±71 vs 88 s ±35, P<0.001), however, there was no difference in eUVC placement time in the group that worked with SC first (115 s ±36 vs 97 s ±35, P=0.161). Physical and functional fidelity of RC were rated higher than SC (P<0.001), and RC were preferred. CONCLUSION: RC has higher physical and functional fidelity, and are preferred for training by pediatric residents, despite longer placement times.

Bronchodilator delivered by metered dose inhaler and spacer improves respiratory system compliance more than nebulizer-delivered bronchodilator in ventilated premature infants.

We compared the change in passive respiratory system compliance (Crs) and resistance (Rrs) after albuterol aerosol treatment administered by either low-flow nebulizer (NEB) or a metered dose inhaler (MDI) and spacer into a ventilator circuit. We hypothesized that albuterol delivered to ventilated infants older than 7 days of life by an MDI and a spacer would improve Crs more than albuterol delivered by a low-flow nebulizer. The treatments were administered 6 hr apart to premature infants with Crs < or = 0.8 mL/cm H2O per kg, requiring ventilation after 7 days of age. Patients served as their own controls and treatment order was randomized. Eighteen studies were performed in eight infants before and 1 and 3 hr after treatment. Differences between methods were compared by analyses of variance. Mean (range) birth weight and study age were 888 (619-1,283) g and 12 (7-29) days, respectively. Mean respiratory system compliance increased by 34% with MDI and by 11% with NEB at 1 hr after treatment (P < 0.02). By 3 hr after treatment, Crs returned to baseline with both methods of aerosol delivery. There was no significant difference in Rrs between the two methods at 1 and 3 hr after treatment. We conclude that albuterol delivered by MDI improves Crs more than low-flow NEB in ventilated premature infants.

When they grow up: the growth of extremely low birth weight (< or = 1000 gm) infants at adolescence.

The growth of 32 extremely low birth weight infants (1000 gm or less) was determined at adolescence. Their height, weight, and head circumference were measured twice in the first year of life and then at ages 2, 3, 5, 8, 10 years, and during adolescence (12 to 18 years). The mean height, weight, and head circumference of the adolescents were at the 50th percentile. Female heights were > or = their mothers; male heights were in the same or greater percentile than those of their fathers. Extremely low birth weight infants experience "catch-up" growth up to and into adolescence and attain predicted biparental genetic height.

A descriptive study of current neonatal nurse practitioner practice.

This study describes the role of the neonatal nurse practitioner (NNP) in current practice and identifies facilitators and constraints to practice perceived by individuals currently practicing as NNPs. The 7-point scale used in this study allowed respondents to identify specific conditions of NNP practice, from highly facilitating (+3) to very constraining (-3). Each item was followed by a clarification section. The questionnaire was mailed to 1,521 individuals holding current NNP certification in the U.S. Data were analyzed using a total facilitation score. The possible range for this score (+225 - (-)225) is based on the numerical range of the scale (+3 - (-)3) multiplied by the 75 items in the facilitation section of the questionnaire. Actual scores ranged from +195 to -114, indicating that NNPs are more facilitated than constrained in their practice. Empirical data generated by this study will help in developing a theoretical model for NNP practice and provide important information for shaping the future role of the NNP.

Symbiosis of nurse and machine through fuzzy logic: improved specificity of a neonatal pulse oximeter alarm.

This article describes the theoretical underpinnings that preceded the design of a new neonatal pulse oximeter alarm that differentiates true from false alarms based on an artificial intelligence theory called "fuzzy logic." The connection between the intuition and sense of advocacy gained through neonatal primary nursing and the application of fuzzy logic to solve the problem of false alarms--that is, the symbiosis between nurse and machine--are explained. Emphasis is placed throughout on the importance of involving nurses in the development of the technology for which they are responsible.

Deficient hypoxia awakening response in infants of smoking mothers: possible relationship to sudden infant death syndrome.

OBJECTIVE: To determine whether fetal exposure to cigarette smoke impairs postnatal chemoreceptor control of ventilation and hypercapnic and hypoxic awakening responses. STUDY DESIGN: Smoking (n = 13) and nonsmoking (n = 34) women were recruited during pregnancy. Serum cotinine levels were measured to assess level of nicotine exposure. The infants were studied at 2 to 3 months of age for ventilatory and awakening responses to hypoxia (17%, 15% and 13% inspired O2) and hypercapnia 4%, 6%, and 8% inspired CO2). Continuous measures were analyzed with unpaired t tests and analysis of variance for repeated measures. Proportions of awakening and periodic breathing were analyzed by means of a comparison of proportions. RESULTS: The infants of smokers had lower birth weights (3022 +/- 566 vs 3518 +/- 491 gm; p < or = 0.005) and were older at the time of study (10.4 +/- 2.8 vs 8.7 +/- 1.3 weeks; p < 0.01) than the control infants. Maternal cotinine levels were higher in smokers (97.8 +/- 107 ng/ml vs no cotinine; p < 0.0001). More infants of smokers failed to awaken with hypoxia than did control infants (54% vs 15%; p = 0.006). The ventilatory responses to hypoxia and hypercapnia were similar in the two groups. All infants awakened with hypercapnia, and there was no difference in the awakening threshold for carbon dioxide (50.3 +/- 4.5 vs 48.3 +/- 5.4 mm Hg; p = 0.28). CONCLUSION: Infants of mothers who smoked during pregnancy have deficient hypoxic awakening responses, which may contribute to the increased risk of sudden infant death syndrome in infants of smoking mothers.

Pulse oximetry and intuition in the neonatal intensive care unit.

This article poses an argument supporting the position that it is important for nurses to become involved, at every level, in the development of the technology that they use. The advantages and disadvantages of one commonly used technological device in the intensive care nursery, the pulse oximeter, are identified. An example of how nursing intuition affected and was incorporated into the design of a new neonatal pulse oximeter is described.

Physiologic measures of kangaroo versus incubator care in a tertiary-level nursery.

OBJECTIVE: To determine the safety and feasibility of kangaroo care in a tertiary-level nursery as defined by apnea, bradycardia, and oxygen desaturation. DESIGN: Prospective, long-term, repeated measures with a convenience sample. SETTING: A 20-bed, tertiary-level nursery with approximately 400 admissions a year. PARTICIPANTS: Eight mother-infant pairs. INTERVENTIONS: Researchers compared incubator care with kangaroo care for 4 hours a day, 6 days a week, for 3 weeks. Physiologic variables were monitored daily and recorded continuously on a polygraph for 8 hours each week. MAIN OUTCOME MEASURES: Amount of apnea, bradycardia, and oxygen desaturation. SECONDARY OUTCOME MEASURES: Heart rate, respiratory rate, percent sleep time, and skin temperature. RESULTS: Apnea, bradycardia, oxygen saturation, heart rate, and respiratory rate were similar during both kangaroo (K) and incubator (I) care. The infants experienced a lower percent (mean +/- standard deviation, K versus I) of total sleep (47 +/- 15 versus 64 +/- 19, p < .003) during kangaroo care. The infants' mean +/- standard deviation temperature during the kangaroo care (36.5 degrees C +/- 0.64 degrees C) was lower (p < .03) than that of the control periods before (36.8 degrees C +/- 0.27 degrees C) or after (36.7 degrees C +/- 0.26 degrees C). Percent sleep time and skin temperature were slightly lower during kangaroo care, but the differences were not clinically significant. CONCLUSION: Kangaroo care is safe and feasible for selected mothers and infants in a tertiary-level nursery.

Functional longevity of the human peritoneum: how long is continuous peritoneal dialysis possible? Results of a prospective medium long-term study.

Long-term peritoneal dialysis requires the maintenance of the transport function of the peritoneal membrane, and appropriate studies of possible changes are necessary. The quantification of peritoneal mass transfer coefficients (MTCs) has been judged to be the ideal method for the evaluation of peritoneal diffusion. The aim of the present study was to show the results of the prospective evaluations in long-term continuous ambulatory peritoneal dialysis patients. We have studied the clinical incidents and peritoneal function of 56 patients who started continuous ambulatory peritoneal dialysis between 1980 and 1988, and have completed at least 3 years of follow-up. Ultrafiltration capacity was calculated with a standardized formula. All patients were studied for peritoneal diffusion of urea and creatinine at least once a year. The evaluation consisted of a kinetic study done by means of a peritoneal equilibration curve for urea and creatinine, applying a bicompartmental mathematical model to calculate the MTCs. The sequential mean values for urea-MTC did not show significant changes over the observation period (20.7 +/- 5.9 mL/min for the first year v 19.8 +/- 6 mL/min for the fifth year). Creatinine-MTC values showed a significant increase over this period in the paired data analysis. The decrease of the urea-MTC to creatinine-MTC ratio may be an early and appropriate index for measuring these changes when the individual values are in the normal range. On the other hand, peritoneal ultrafiltration capacity significantly decreased over this period (1,800 +/- 530 mL/d v 1,400 +/- 600 mL/d, P < 0.01). The high rate of accumulated days of peritoneal inflammation was related to these significant changes, and thus may be proposed to be a good prognostic index of long-term peritoneal survival. These long-term functional changes might be related to the effect of injuries on the preservation of the normal peritoneal structure. We conclude that after 5 to 11 years, the human peritoneum shows functional stability (diffusion and water transport) in patients with low rates of peritoneal inflammation. With a few exceptions, represented by patients with a high rate of peritoneal inflammation, long-term peritoneal dialysis accomplished its newly entrusted task.

Gentamicin nephrotoxicity in rats is not modified by verapamil.

To assess whether calcium could be involved in the gentamicin-induced nephrotoxicity, we have studied the effect of the calcium channel blocker verapamil on renal function in rats intoxicated by gentamicin. Male Wistar rats were divided in three groups. In group I (n = 7) they were injected with gentamicin 100 mg/kg body wt/day s.c. for 5 days. In group II (n = 6), they received gentamicin and verapamil s.c. 2 mg/rat/day. In group III rats served as control. Plasma creatinine and creatinine clearance were daily measured. Rats treated with gentamicin showed a progressive increase in plasma creatinine and a drop in creatinine clearance. No differences between rats treated with gentamicin and those with gentamicin plus verapamil were observed. The urinary flow decreased after treatment with gentamicin, this decrease being more marked in rats treated with verapamil. No differences in daily urinary sodium and potassium excretion were found between intoxicated rats treated or not with verapamil. The present results show that, in rats, verapamil has no protective effect against the nephrotoxicity of gentamicin.

Reconciliation and healing for mothers through skin-to-skin contact provided in an American tertiary level intensive care nursery.

Feasibility and safety of skin-to-skin contact through the Kangaroo method of care in a modern American tertiary intensive care was studied, as well as effects of this innovative care on mother's emotional reactions. Eight mother infant dyads participated in skin-to-skin contact a minimum of 4 hours each day for six days per week during a period of three consecutive weeks. The cognitive adaptation framework was used to identify themes in maternal responses. During the first week, mothers were preoccupied with childbirth events in attempts to understand their sense of loss and victimization. During the second week, maternal emotions intensified and manifested in fears for the baby's well-being and a need to discuss negative and positive emotional reactions to having a premature and sick baby. All mothers requested respite time from skin-to-skin contact, so they could deal with their emotional crises. By the third week, mothers had an increased sense of meaning, mastery, and self-esteem about what had happened to themselves and their infants. Themes of reconciliation and healing occurred when mothers placed their infant skin-to-skin in the Kangaroo position over the three consecutive weeks that this type of nursing care was experienced.

An analysis of adequacy of dialysis in a selected population on CAPD for over 3 years: the influence of urea and creatinine kinetics.

Adequacy of dialysis is addressed to minimize the negative consequences of underdialysis. The results of the NCSD demonstrated that urea kinetic modelling (UKM) is a useful tool in the measurement of adequacy of dialysis: Kt/V values of 1 are considered adequate to prevent complications when daily protein intake is appropriate. For CAPD no similar prospective studies exist, and consequently there is no information comparable to that for haemodialysis. Preliminary data have communicated controversial results about the usefulness of UKM for CAPD prescription. On the other hand creatinine kinetics has been proposed as an alternative to UKM to define adequacy of dialysis on CAPD. However, these results should be considered preliminary because of the small size of the series and the short observation period. The objective of this paper is to study the role of these two kinetic models in defining adequacy of dialysis in a long-term, selected CAPD population. We have studied 56 patients treated for at least 3 years on CAPD (3-11 years; mean observation period 5 years; 3996 patient-months). Urea kinetic model (UKM) (urea weekly (W) Kt/V and NPCR) and creatinine kinetics (Efficacy number (EN) and K) were determined annually. According to the present data we can conclude that Kt/V is an appropriate tool for defining adequacy in patients on CAPD. Values of weekly Kt/V greater than 1.7-1.8, with NPCR more than 1 g/kg/day, assure an adequate clinical outcome. Conversely, values on the Kt/V scale less than 1.7 entail a greater rate of complications. Our data also confirm that maintaining a serum albumin > 536-551 mumol/l (3.7-3.8 g/dl) is related to lower morbidity and mortality, and should be a major objective for CAPD patients. Consequently a relationship between dose of dialysis in terms of urea mass balance and protein nutrition can be established. After 5 years on CAPD, when all residual renal function is generally lost, Kt/V values in excess of 1.9 are difficult to achieve. Based on currently available information, we do agree with the interest of performing a prospective study on adequacy of dialysis based on the urea kinetic model in CAPD, which definitely defines its role. On the other hand, creatinine kinetics did not show sufficient discriminative capacity in terms of adequacy of dialysis. EN and Kt of creatinine values in the lower range (4.5-6 and less than 45-50 1/week respectively) were not necessarily associated with a poorer clinical outcome.(ABSTRACT TRUNCATED AT 400 WORDS)

Pulmonary mechanics in premature infants one month after treatment with synthetic surfactant.

During the double-blind, multicenter trials of the synthetic surfactant Exosurf Neonatal, we measured pulmonary mechanics at 28 days of age in 30 surfactant- or placebo-treated infants. In the 20 surfactant-treated and 10 air-treated infants studied, there were no differences in lung compliance or resistance at 28 days of age. These observations suggest that improvements in pulmonary function reported early in the neonatal course after the administration of exogenous surfactant are not detectable at 28 days of age.

Effect of platelet activating factor antagonist treatment on gentamicin nephrotoxicity.

To assess whether PAF could be involved in the gentamicin-induced nephrotoxicity, we have studied the effect of PAF antagonist BN-52021 on renal function in rats after gentamicin (GENTA) treatment. Experiments were completed in 21 Wistar rats divided into three groups: group GENTA was injected with gentamicin 100 mg kg(-1) body wt/day s.c. for 6 days. Group GENTA + BN received gentamicin and BN-52021 i.p. 5 mg kg(-1) body wt/day. A third group served as control. Rats were placed in meta-bolic cages and plasma creatinine and creatinine clearance were measured daily. GENTA group showed a progressive increase in plasma creatinine, a drop in creatinine clearance and an increase in urinary excretion of N-acetyl-beta-D-glucosaminidase and alkaline phosphatase. GENTA + BN group showed a lesser change in plasma creatinine and a creatinine clearance, but no difference with GENTA group in urinary excretion of NAG and AP were observed. Histological examination revealed a massive cortical tubular necrosis in rats treated with gentamicin, whereas in BN-52021 injected animals tubular damage was markedly attenuated. The present results suggest a role for PAF in the gentamicininduced nephro-toxicity.

Nursing interventions. The nurse's role in the care of a 730 g baby treated with prostaglandins for 62 days for a coarctation of the aorta.

As techniques for saving very low birth weight babies improve, there will be a need to maintain babies with cardiac lesions on continuous infusions of prostaglandins until they gain enough weight so that corrective surgery can be performed. An organized approach to overcome the problems of prematurity through primary nursing is essential when caring for the very low birth weight baby with congenital heart disease requiring long-term prostaglandin therapy.