Ultrasound evaluation of piglet diaphragm function before and after fatigue

Clinically, a noninvasive measure of diaphragm function is needed. The purpose of this study is to determine whether ultrasonography can be used to 1) quantify diaphragm function and 2) identify fatigue in a piglet model. Five piglets were anesthetized with pentobarbital sodium and halothane and studied during the following conditions: 1) baseline (spontaneous breathing); 2) baseline + CO2 [inhaled CO2 to increase arterial PCO2 to 50-60 Torr (6.6-8 kPa)]; 3) fatigue + CO2 (fatigue induced with 30 min of phrenic nerve pacing); and 4) recovery + CO2 (recovery after 1 h of mechanical ventilation). Ultrasound measurements of the posterior diaphragm were made (inspiratory mean velocity) in the transverse plane. Images were obtained from the midline, just inferior to the xiphoid process, and perpendicular to the abdomen. M-mode measures were made of the right posterior hemidiaphragm in the plane just lateral to the inferior vena cava. Abdominal and esophageal pressures were measured and transdiaphragmatic pressure (Pdi) was calculated during spontaneous (Sp) and paced (Pace) breaths. Arterial blood gases were also measured. Pdi(Sp) and Pdi(Pace) during baseline + CO2 were 8 +/- 0.7 and 49 +/- 11 cmH2O, respectively, and decreased to 6 +/- 1.0 and 27 +/- 7 cmH2O, respectively, during fatigue + CO2. Mean inspiratory velocity also decreased from 13 +/- 2 to 8 +/- 1 cm/s during these conditions. All variables returned to baseline during recovery + CO2. Ultrasonography can be used to quantify diaphragm function and identify piglet diaphragm fatigue.     

One-step fluorescent probe product-enhanced reverse transcriptase assay

The Chiari type II malformation is the leading cause of death in infants with myelomeningocele. The authors report 17 cases of symptomatic Chiari type II malformation occurring in two distinct age dependent population. In Group I, 13 neonates and infants in the first year of life presented with cranial nerve and brain stem dysfunction characterized by vocal cord paralysis, apnea, dysphagia and laryngeal stridor. In Group II, 4 patients developed signs and symptoms after the first year of life. In this group, the presentation was more insidious and included neck pain and cerebellar manifestations. The surgical treatment consisted initially in shunt implantation or revision and when there was no improvement, posterior fossa decompression was performed. The response to the surgical treatment differed considerably between the two groups: older patients improved promptly after surgery and there was no casualties; in newborn and infants, especially those under 6 months of age, the mortality rate was 46.1%. The authors stress that prompt diagnosis and surgical intervention should be performed in order to produce a favorable outcome.     

Real-time X-ray diffraction study at different scan rates of phase transitions for dipalmitoylphosphatidylcholine in KSCN

A questionnaire survey was carried out to examine the attitudes and practices of Australian and New Zealand intensivists with regard to brain death and organ donation. A return rate of 82.5% was achieved. Fifty-eight per cent had written evidence of their own wishes to donate organs and 94% would agree to donation from a dependent. At least one intensivist is involved in certifying brain death on 95% of occasions. Intensivists are involved in the request for organ donation over 90% of the time although one-third do not believe that it is their role to request organ donation. Although two-thirds believe that the family should always be approached for organ donation, another 52 out of 254 indicated that it was their (the intensivist's) role to decide if families should be asked for organ donation. Possible reasons for not requesting are language or other communication problems, perceptions of cultural differences and degrees of family distress. Twenty per cent of respondents do not provide haemodynamic support before brain death confirmation. Australian and New Zealand intensivists overwhelmingly support the concept of brain death, current methods of confirmation of brain death, organ donation and transplantation. Possible reasons behind loss of potential donors include decisions not to resuscitate both before and after brain death is confirmed. Perceptions of family grief and cultural differences clearly inhibit requests for organ donation. A very few units have an effective policy on approaching families about organ donation. Intensivists have almost exclusive control over requests for organ donation and thus bear a full professional responsibility for this element of hospital practice.     

Motion patterns of Nabesna Glacier (Alaska) revealed by interferometric SAR techniques

Nabesna Glacier is one of the longest land-terminus mountain glaciers in North America. However, its flow has never been studied. We derived detailed motion patterns of Nabesna Glacier in winter and spring 1994–1996 from the synthetic aperture radar (SAR) images acquired by the European Remote Sensing satellites (ERS-1 and ERS-2) using interferometric SAR (InSAR) techniques. Special effort was made to assess the accuracy of the motion estimates, and remove data points with high uncertainty from the motion profiles, enabling us to obtain reliable glacier flow patterns along the highly curved main course of Nabesna Glacier. The results, covering 80 km of the 87 km main course of the glacier, were used to delineate four distinctive sections in terms of spatial and temporal variability of the glacier speed: (1) the upper section where glacier flow was apparently random both temporally and spatially presumably due to development of crevasses; (2) the upper-middle section with relatively steady flow around 0.27 to 0.4 m/day; (3) the middle section with a stable pattern of acceleration from 0.27–0.3 m/day to the maximum about 0.67–0.73 m/day, followed by a general deceleration to 0.17–0.33 m/day before reaching (4) the lower section where the glacier motion was generally slow yet highly variable although uncertainty in the estimation is high. Occurrence of the flow maximum, as well as many local maxima and minima at consistent locations over different periods suggests that the valley geometry affect the overall flow pattern. On top of this general trend, many small-scale temporal/spatial variations in the glacier flow patterns were observed along the glacier, especially in the lower sections. On average, the flow speeds were in the range of 0.3 to 0.7 m/day; however this lacks any measurements of summer flow speeds which are expected to be significantly higher.     

Access to hypertensive care. Effects of income, insurance, and source of care

BACKGROUND: This study examines the relationship between income, health insurance, and usual source of care characteristics and screening and management of hypertension. METHODS: This is a secondary analysis of data from the 1987 National Medical Expenditure Survey. Adult survey respondents constitute a sample representative of the total adult noninstitutionalized US population. Screening, follow-up care, and pharmacologic treatment for hypertension were examined among low income individuals, the uninsured, those without a usual source of care place, and those without a particular usual source of care physician. RESULTS: The uninsured, individuals without a usual source of care place, and those without a particular usual source of care physician received less screening, follow-up care, and pharmacologic treatment for hypertension. Income did not affect receipt of hypertensive care. CONCLUSIONS: Lack of health insurance and lack of a usual source of care are barriers to hypertensive care. Policies that increase access to health insurance or to usual source of care physicians may enable more individuals to attain control of hypertension.     

Ambient, biological, and biological effect monitoring of exposure to polycyclic aromatic hydrocarbons (PAHs)

A novel strategy was utilised to assess the risk to health from exposure to polycyclic aromatic hydrocarbons (PAHs). Ambient monitoring was carried out by personal sampling. Urinary thioethers (UTh) and urinary 1-hydroxypyrene (1-HP) were utilised for biological monitoring. Urinary d-glucaric acid (UDGA) and sister chromatid exchange (SCE) in peripheral blood lymphocytes were used as biological effect markers. The population was categorised into exposed and control groups according to the external dose of PAHs. The excretion of 1-HP in the controls over the 3-day period showed a relatively stable baseline, while the exposed showed a significant increase over the same period of time. SCE frequency in the exposed population was significantly different from controls.     

Observers for stabilization of systems with matched uncertainty

In this article, we study the design of observer-based robust linear feedback controllers. The uncertainty, which can enterA, and either theB orC matrices, is assumed to satisfy certain matching conditions. Lyapunov techniques are used to establish sufficient conditions for stability, given an uncertainty bound. In particular, sufficient conditions are obtained that, if met, result in stabilizing controllers regardless of the size of the uncertainty entering the system matrix, as long as the standard constraints on the uncertainty entering the input or output matrices are met. As with the case of more general forms of uncertainty, the resulting observers often have high gains. To study performance, the problem of disturbance rejection is considered. Sufficient conditions are presented for obtaining control laws that stabilize the closed loop system, regardless of the size of the uncertainty entering the system matrix, while simultaneously guaranteeing arbitrarily small infinity norm for the transfer function from the plant disturbances to the outputs.