Impact of UK National Guidelines based on FRAX®--comparison with current clinical practice.

OBJECTIVE: To assess whether clinician-determined treatment intervention thresholds are in line with the assessment of fracture risk provided by FRAX® and treatment recommendations provided by UK guidelines produced by the National Osteoporosis Guidelines Group (NOGG). DESIGN, PATIENTS AND MEASUREMENTS: This was a retrospective cohort analysis of 288 patients consecutively referred for dual-energy X-ray absorptiometry (DXA) scanning from primary care immediately prior to the introduction of the FRAX® algorithm. In addition to DXA assessment, patients completed a clinical risk factor questionnaire which included risk factors used in the FRAX® algorithm. Initial risk assessment and treatment decisions were performed after DXA. FRAX® was used, retrospectively, with femoral neck T-score, to estimate fracture risk which was applied to NOGG to generate guidance on treatment intervention. Clinician- and NOGG-determined outcomes were audited for concordance. RESULTS: There was concordance between clinician and NOGG treatment decisions in 215 (74.6%) subjects. Discordance was observed in 73 (25.3%) subjects. In the discordant group, seven subjects were given lifestyle advice when NOGG recommended treatment, 42 given treatment when NOGG recommended lifestyle advice only, and 24 were referred to a metabolic bone clinic for further evaluation. The reasons for treatment differences in subjects recommended treatment by clinician but not NOGG were largely (90.2%) attributed to the use of lumbar spine bone mineral density (BMD). CONCLUSIONS: There is high concordance between clinician-determined and FRAX®-NOGG intervention. The absence of spine BMD from FRAX® is the primary source of discrepancy. This study provides some assurance of the validity of the treatment thresholds generated from FRAX®-NOGG in 'real-world' usage.

Pediatric in vivo cross-calibration between the GE Lunar Prodigy and DPX-L bone densitometers.

Dual energy x-ray absorptiometry (DXA) machine cross-calibration is an important consideration when upgrading from old to new technology. In a recent cross-calibration study using adult subjects, close agreement between GE Lunar DPX-L and GE Lunar Prodigy scanners was reported. The aim of this work was to cross-calibrate the two machines for bone and body composition parameters for pediatrics from age 5 years onwards. One-hundred ten healthy volunteers aged 5-20 years had total body and lumbar spine densitometry performed on DPX-L and Prodigy densitometers. Cross-calibration was achieved using linear regression and Bland-Altman analysis. There was close agreement between the machines, with r2 ranging from 0.85 to 0.99 for bone and body composition parameters. Paired t-tests demonstrated significant differences between machines that were dependent on scan acquisition mode, with the greatest differences reported for the smallest children. At the lumbar spine, Prodigy bone mineral density (BMD) values were on average 1.6% higher compared with DPX-L. For the total body, there were no significant differences in BMD; however, there were significant differences in bone mineral content (BMC) and bone area. For small children, the Prodigy measured lower BMC (9.4%) and bone area (5.8%), whereas for larger children the Prodigy measured both higher BMC (3.1%) and bone area (3.0%). A similar contrasting pattern was also observed for the body composition parameters. Prodigy values for lean body mass were higher (3.0%) for small children and lower (0.5%) for larger children, while fat body mass was lower (16.4%) for small children and higher (2.0%) for large children. Cross-calibration coefficients ranged from 0.84 to 1.12 and were significantly different from 1 (p<0.0001) for BMC and bone area. Bland-Altman plots showed that within the same scan acquisition modes, the magnitude of the difference increased with body weight. The results from this study suggest that the differences between machines are mainly due to differences in bone detection algorithms and that they vary with body weight and scan mode. In general, for population studies the differences are not clinically significant. However, for individual children being measured longitudinally, cross-over scanning may be required.

The relationship between lean body mass and bone mineral content in paediatric health and disease.

INTRODUCTION: The correct interpretation of DXA data is critical to the diagnosis and management of children with suspected bone disease. This study examines the various influences on bone mineral content (BMC), as measured by dual-energy X-ray absorptiometry (DXA). MATERIALS AND METHODS: Six hundred and forty-six healthy school children and forty-three children with chronic diseases, aged 5-18 years, had their lumbar spine and whole body measured using a Lunar DPX-L DXA scanner. RESULTS: Stepwise linear regression identified lean body mass (LBM) as the strongest single predictor of BMC in the lumbar spine and the total body. A significant gender difference was observed in the relationship between BMC and LBM with girls having significantly more bone per unit LBM from 9 years of age in the spine and 13 years of age in the total body. To investigate the relationship between LBM and BMC in children with chronic disease, a two-stage algorithm based upon calculation of Z scores from the normative data was applied. Stage 1 assessed LBM for height and stage 2 assessed BMC for LBM. Ten children with spinal muscular atrophy had a mean LBM for height Z score of -1.8(1.4) but a mean BMC for LBM Z score of 1.2(1.3) indicating their primary abnormality was reduced muscle mass (sarcopenia) with no evidence of osteopenia. In contrast, 21 children with osteogenesis imperfecta had a mean LBM for height Z score of 0.4(1.7) but a mean BMC for LBM Z score of -2.5(1.8) indicating normal LBM for size but significantly reduced BMC for LBM (i.e. osteopenia) confirming a primary bone abnormality. A third group consisting of 12 children with low trauma fractures demonstrated little evidence of sarcopenia [mean LBM for height Z score -1.1(2.1)] but significant osteopenia [mean BMC for LBM Z score -1.9(1.5)]. CONCLUSION: The results from this study demonstrate how the relationship between height and lean body mass, and lean body mass and bone mineral content can be a useful method of diagnosing osteoporosis in children and how the relationships can be used to identify if the primary abnormality is in muscle or bone.

Bone density and body composition in children with growth hormone insensitivity syndrome receiving recombinant IGF-I.

OBJECTIVE: There are few reports of the metabolic action of insulin-like growth factor 1 (IGF-I) in vivo. Growth hormone insensitivity syndrome is a good model to examine the effects of IGF-I deficiency. This study was designed to assess body composition and bone density in children with growth hormone insensitivity syndrome before and after receiving treatment with recombinant IGF-I. DESIGN: A prospective longitudinal study. PATIENTS: Four prepubertal boys age 6.1-9.8 years with short stature due to growth hormone insensitivity syndrome. MEASUREMENTS: Assessment of body fat by skinfold thickness measurements and dual energy X-ray absorptiometry (DXA) was made during the first 6 months of recombinant IGF-I treatment. Assessment of lumbar spine bone density by DXA was performed prior to IGF-I treatment and during the subsequent five years. RESULTS: Each child showed a significant reduction in fat mass (0.26-1.22 kg) after 6 weeks of IGF-I treatment. Bone density prior to treatment was reduced in comparison to age-matched controls but calculated volumetric bone density was within the normal range. Volumetric bone density progressively improved over the 5-year treatment period. CONCLUSIONS: Children with growth hormone insensitivity syndrome exhibit a metabolic response to IGF-I within 6 weeks analogous to that seen in GH-deficient children receiving GH. Bone density when corrected for body size is within normal limits and demonstrates a response to IGF-I, confirming the anabolic action on bone.

Bone density in the Asian thalassaemic population: a cross-sectional review.

UNLABELLED: As survival improves in beta-thalassaemia, osteoporosis is emerging as a significant problem. This study examines bone mineral density (BMD) of thalassaemic patients of Asian origin (age range 9.5-24 y) to evaluate the extent of problems in this group and identify potential risk factors. Eleven patients were scanned using dual-energy X-ray absorptiometry. BMD z-scores and the bone mineral apparent density (BMAD) z-scores were calculated, to correct for short stature. All but three patients had lumbar spine BMD and BMAD z-scores below the mean. Three patients had BMAD z-scores more than 2.5 standard deviations below the mean. A negative correlation between age and BMAD was seen, as was an association between endocrine disorders and decreased bone density. CONCLUSION: The data confirm significant reductions in BMD in the Asian thalassaemic population, even after correcting for body size. Further research is needed to identify risk factors and means of prevention.

Use of quantitative ultrasound to assess bone status in children with juvenile idiopathic arthritis: a pilot study.

Periarticular osteoporosis around inflammed joints and generalized osteoporosis have been shown to be markers of disease activity and severity in children with juvenile idiopathic arthritis (JIA). Bone mineral density (BMD) in adults can be assessed precisely by dual X-ray absorptiometry (DXA), but this technique has not been used widely in children. Quantitative ultrasound (QUS) may provide an alternative method for assessment of bone status. The aim of this pilot study was to compare QUS to DXA in assessing generalized osteoporosis in a cohort of patients JIA. Twenty-two Caucasian children (15 females, 7 males) with JIA of duration 19-142 months (mean 71 mo) and age 7-17 yr were recruited. Total body and lumbar spine BMD and bone mineral content (BMC) were measured by DXA using standard procedures on a Lunar DPX-L scanner. QUS was performed using Myriad SoundScan 2000. Speed of sound (SOS) was measured at the right midtibia. The DXA results were compared to QUS using linear regression analysis. Spine and total body BMD measured by DXA correlated significantly with tibia SOS (spine: r = 0.57, p < 0.007; total body: r = 0.68, p < 0.001). Spine BMC was similarly related to SOS as BMD (r = 0.58, p < 0.007). Individual patient weight and height were strong predictors of BMD, but only moderate predictors of SOS. The mean spine BMD was lower in the JIA patients compared to the normal ranges (mean Z-score of -1.19). BMD Z-scores were negatively associated with disease duration. Patients taking steroids were associated with lower Z-scores. In conclusion, SOS shows a significant correlation with BMD as measured by DXA, albeit with wide 95% confidence intervals in this small pilot study. QUS was also well tolerated and was technically easy to perform in these children. With the added advantage that it is free from radiation risk, further assessment of this potentially valuable tool for measuring bone status in children is warranted.

Intravenous pamidronate in juvenile osteoporosis.

AIMS: To investigate the use of the aminobisphosphonate, disodium pamidronate, in children with vertebral osteoporosis. METHODS: Five children (aged 10-15 years) with vertebral osteoporosis who developed compression fractures in the thoracic and/or lumbar spine as a consequence of five different conditions, received treatment with intravenous disodium pamidronate in doses ranging from 0.5 to 12 mg/kg/y. RESULTS: Each child had rapid pain relief following the first treatment, followed by large increments in lumbar spine bone density over one year; the change in bone density standard deviation score ranged from 0.5 to 2.5 with percentage increments of 26% to 54%. CONCLUSION: Intravenous pamidronate appears to be a useful therapeutic option in childhood osteoporosis, but its use in children must still be regarded as experimental and therefore closely monitored.

A comparison of performance of three gamma camera systems for positron emission tomography.

The development of coincidence positron imaging using a gamma camera should significantly increase PET utilization. This study has compared the performance of three such systems with each other and with an equivalent single photon emission computed tomography (SPECT) measurement. A Carlson phantom, which consisted of a 20 cm diameter cylinder containing areas of uniform activity, hot lesions, cold lesions and orthogonal alternate hot and cold lines, was filled with an activity of 18F chosen to try and best exploit each camera and imaged for a fixed time (27 min). The image quality of 9 mm thick slices in each section of the phantom was compared visually. Several image quality parameters were also compared including line source resolution and noise equivalent count rate. There were considerable differences in PET image quality between the three cameras but all were at least as good as the SPECT image. The full width at half maximum (FWHM) resolution of all systems was similar (approximately 4.5 mm) but the maximum noise equivalent count rates in a 20 cm cylinder were significantly different (6.3, 2.6 and 1.6 kcps) (where cps is counts per second) and correlated with the phantom image quality.

Factors influencing the speed of sound through the proximal phalanges.

The amplitude-dependent speed of sound (AD-SOS) in the proximal phalanges is reported to be sensitive to osteoporotic changes. We investigated the influence of bone thickness and cortical thickness on AD-SOS. Phantoms made of Perspex were designed to simulate different bone width (11-16 mm) and cortical thickness (3-7.5 mm). The phantoms were designed with two opposing flat and cylindrical surfaces. The effect of cortical thickness was examined by drilling holes (simulating the medullary canal) of different diameters (1-7 mm) in the middle of the Perspex cylinders. The effect of sample thickness was investigated on solid Perspex phantoms of varied lengths. The standardized precision errors of AD-SOS measurement in vivo and in vitro on volunteers and phantoms were 2.8 and 0.9%, respectively. AD-SOS was influenced by the bone width, cortical thickness, and location along the phalanx. A decrease in either cortical width or cortical thickness resulted in a decrease in AD-SOS. The effect is dependent on whether the contact surface is curved or flat. It is possible that a curved surface has a focusing effect on the wave through the porous core, whereas for a flat surface, the path of the waves might not pass through the center. When cortical thickness and bone width were expressed as a ratio, there was a linear relationship between this ratio and AD-SOS through the phantoms. AD-SOS was independent of thickness for samples greater than 11 mm.

Assessment of mucociliary transport in patients with chronic mucoid rhinitis.

Chronic rhinitis is the manifestation of a heterogeneous group of disease entities and often proves difficult to manage successfully. We present the investigations of the mucociliary system in 40 patients with mucoid rhinorrhoea as their principal symptom of whom 20 had pan respiratory disease. The saccharin clearance time (SCT) was measured and classified as normal if it was below 20 min. Objective measurement of clearance was made using 99mTechnetium-labelled human serum albumin (99mTc-HSA). We have standardized our method using a micrometer syringe driver to produce a droplet of consistent size (droplet size, 0.01 ml, SD 0.0002 ml) that reduces the dose of radiation. The movement of the droplet was measured over 20 min (RLT). The mean, maximum rate and percentage moved were calculated. Patients were divided into those who had chest disease (20) and those without and a chi 2-test was performed for the mean RLT time between the two groups. There was a strong correlation between mean and maximum rates (r = 0.91). One patient has a normal SCT and normal RLT. Patients with chest disease had a significantly lower mean RLT (P > 0.01). Assuming that RLT is the standard investigation, six patients were normal but had an abnormal SCT, this is a false positive error of 15%. The false negative error was 4/40 (10%). The association between sinus and chest disease with abnormal mucociliary clearance is stressed.

Evaluation of finger ultrasound in the assessment of bone status with application of rheumatoid arthritis.

Osteoporosis associated with active rheumatoid arthritis (RA) has been demonstrated in both the axial and peripheral skeleton, especially the periarticular regions more directly affected by the disease. Quantitative ultrasound (QUS) is a recently accepted tool for the assessment of bone status, and therefore could be used to monitor bone changes in RA patients. In a cross-sectional study we measured ultrasound velocity (Ad-SOS) through the proximal phalanges in three groups of female subjects. These included: 51 patients with rheumatoid arthritis (group 1), 44 general practitioner (GP)-referred patients for osteopenia (group 2) and 52 young healthy volunteers (group 3). For groups 1 and 2 bone mineral density (BMD) of the lumbar spine and proximal femur were also measured. For the RA patients BMD of the hand, measurement of hand function (HAQ and grip strength) and disease activity (ESR and CRP) were also assessed. The precision of long-term Ad-SOS measurements on volunteers gave a root mean square coefficient of variation (CV) of 0.7% and standardized CV of 3.6%. No statistically significant effect of dominance was observed in the measured Ad-SOS between the dominant and non-dominant hand (r = 0.96, p < 0.001). Ad-SOS was found to be significantly different in the three groups (p < 0.0001). Ad-SOS was highly dependent on age (r = -0.67), with a gradual reduction (-5.2 m/s per year) after the age of 30 years for female patients in both group 1 and group 2. Ad-SOS was significantly correlated with lumbar spine, femoral neck and hand BMD, with correlation coefficients of 0.49, 0.51 and 0.72 respectively for RA patients. Finger ultrasound was moderately correlated with measures of hand function, with coefficients of 0.37 and 0.39 for HAQ and grip strength respectively. Hand BMD also correlated to the same power with these parameters. Neither finger ultrasound nor BMD was significantly correlated with ESR and CRP (measures of disease activity). We have demonstrated that bone status can be assessed quickly and cheaply using a portable QUS device. Ad-SOS relates to the measure of hand function in RA patients. Longitudinal studies are required to determine the usefulness of finger ultrasound for monitoring disease progression or the effect of treatment in RA.

Preliminary clinical study of the distribution of HPMA copolymers bearing doxorubicin and galactosamine.

Galactose-targeted delivery of macromolecules and drug conjugates to asialoglycoprotein receptor (ASGPR) positive cells has been widely documented in animals, although targeting in humans has never been demonstrated. In this study we report the pharmacokinetics and imaging determined in the first patient enrolled in a phase I clinical study of the poly[N-(2-hydroxypropyl)methacrylamide] copolymer bearing doxorubicin and galactosamine, known as PK2. Gradient high performance liquid chromatography (HPLC) evaluation of plasma and urine has been combined with 123I-based imaging to show biphasic clearance of the drug from the plasma (half-lives of 78+/-1 and 990+/-15), and approximately 30% delivery of the drug to the hepatic region, as determined by planar whole body imaging at 24 h. This patient has a multifocal hepatoma, and single photon emission computed tomography (SPECT) analysis showed a ratio of tumour tissue to normal liver uptake of approximately 1:3, at 24 h. On the basis of this patient, effective hepatic targeting can be achieved following an intravenous dose of 20 mg/m2 doxorubicin as PK2, however the therapeutic usefulness of this targeted drug has yet to be established.

Variation in bone mineral density between different anatomical sites in a normal local population.

Bone mineral density (BMD) measured using dual energy X-ray absorptiometry (DXA) can be expressed in terms of standard deviations, above or below mean young adult T-scores and above or below age-matched Z-scores. The differences between the left neck of the femur (LN), right neck of the femur (RN) and lumbar spine (L2-L4) were statistically significant, irrespective of whether expressed as T-scores or Z-scores. Therefore skeletal status assessment should involve as many sites as practically possible. Considering the low radiation dose and short scanning time, it is suggested that at least the two femurs and lumbar spine BMD be used in routine osteoporosis risk assessment.

The use of quantitative ultrasound to monitor fracture healing: a feasibility study using phantoms.

Fracture healing has traditionally been monitored subjectively using manual manipulation of the fracture site and evaluation of radiographic images. A more objective method of monitoring would provide obvious advantages, allowing healing progress to be quantitatively assessed and so providing the opportunity for early detection of problems. A tibia phantom was used to investigate whether the longitudinal propagation velocity of ultrasound across a fracture site could be used quantitatively to assess fracture healing. The characteristic of fracture healing simulated by the phantom was the changing gap between the bone ends at the fracture site. The ultrasound velocity was measured using a recently developed machine, the SoundScan 2000 (Myriad Ultrasound Systems Ltd, Israel). The precision of the SoundScan 2000 was found to be 0.4% in vitro. Ultrasound velocity predicted the simulated fracture gap with a high degree of accuracy (R2 = 0.994). The measured and the theoretically calculated velocity for different widths between the simulated bone ends was found to be highly correlated with a coefficient of determination of 0.998. This result shows that the use of quantitative ultrasound to monitor fracture healing warrants further investigation in vivo.

Prevention of remote organ injury in cardiopulmonary bypass: the impact of flow generation technique.

The purpose of this study was to investigate the effects of 3 different types of flow generation for cardiopulmonary bypass on gastrointestinal permeability and on neutrophil expression of CD11b, a surface marker of neutrophil activation. Fourteen patients undergoing elective coronary revascularization were selected randomly to receive 1 of the 3 flow generation techniques (roller, pulsatile, or centrifugal). Intestinal permeability was assessed by the fraction of an oral dose of 51chromium-ethylenediaminetetraacetate (51Cr-EDTA) recovered in the urine over 24 h. Neutrophil activation was determined by expression of CD11b markers at 6 time points. Overall, the 14 patients showed significant increases in intestinal permeability. It was not possible to demonstrate statistically significant differences among the flow generation groups; however, when compared to both roller pump groups, the centrifugal pump group showed a 3.2% reduction in intestinal permeability. There was no change in the expression of CD11b receptors throughout the time points, nor was there a relationship of CD11b markers to the flow generation technique.

Radiation dose and in vitro precision in paediatric bone mineral density measurement using dual X-ray absorptiometry.

Dual X-ray absorptiometry (DXA) is one of the most widely used techniques for non-invasive assessment of bone integrity. There is a growing demand for measurement of paediatric bone status. In DXA the principal radiation risks to patients are the carcinogenic and genetic effects. Radiation dosimetry is well established for DXA in adults, but there are limited paediatric data available. We report on a study to estimate the effective doses (EDs) received by typical 5- and 10-year-old children using the paediatric scan mode on the Lunar DPX-L bone mineral density scanner. Entrance surface doses (ESDs) and percentage depth doses for the total body and PA spine scan modes were measured using lithium borate thermoluminescent dosemeters (TLDs) located at the surface and distributed at various organ locations in anthropomorphic child phantoms. The EDs were calculated from the percentage depth doses, amount of each organ irradiated and tissue weighting factors. The ESDs were measured to be 6.0 and 0.12 microGy for the posteroanterior (PA) spine and total body, respectively. PA spine EDs were calculated as 0.28 and 0.20 microSv for the 5- and 10-year-old, respectively. Total body EDs were 0.03 and 0.02 microSv for the 5- and 10-year-old children, respectively. These results compare with an adult ED of 0.21 microSv for the PA spine. They are also more than two orders of magnitude lower than reported ESDs and EDs for paediatric chest X-rays. Bone mineral density (BMD) short-term in vitro precision was 0.5% and 1% in the 5- and 10-year-old phantoms, respectively. In conclusion, the Lunar DPX-L in the paediatric mode has a high precision and very low radiation doses, similar to those reported for the adult mode.

The role of ultrasound in the assessment of osteoporosis: a review.

Osteoporosis is now being recognized as a "silent epidemic" and there is an increasing need to improve its diagnosis and management. Quantitative ultrasound (QUS) measurement [broadband ultrasound attenuation (BUA) and velocity] is emerging as an alternative to photon absorptiometry techniques in the assessment of osteoporosis. The fundamental principles governing ultrasound measurements are discussed, and some of the commercially available clinical systems are reviewed, particularly in relation to data acquisition methods. A review of the published in vivo and in vitro data is presented. The general consensus is that ultrasound seems to provide structural information in addition to density. The diagnostic sensitivity of ultrasound measurement of the calcaneus in the prediction of hip fracture has been shown by recent large prospective studies to be similar to hip bone mineral density (BMD) measured with dual-energy X-ray absorptiometry (DXA) and superior to spine BMD. Ultrasound has also been shown to correlate better with the type of hip fracture (intertrochanteric or cervical) than BMD and to provide comparable diagnostic sensitivity to spine BMD in vertebral fractures. It has also been observed that combining the results of both ultrasound and DXA BMD significantly improved hip fracture prediction. Areas where further research is required are identified.

Prediction of human femoral bone strength using ultrasound velocity and BMD: an in vitro study.

The stiffness and strength of cancellous bone are important in the management of skeletal diseases such as osteoporosis. These properties are a function not only of bone density but also of bone architecture, some measure of which can be provided by quantitative ultrasound. The ability of quantitative ultrasound and bone mineral density (BMD) to predict stiffness and strength of human femoral heads removed from live subjects during hip replacement was assessed. Stiffness and strength were measured using a uniaxial compression test. Ultrasound velocity was measured using the pulse-submersion technique (McCue CUBAResearch) and BMD using DXA (Lunar DPX-L). Ultrasound velocity (quantitative ultrasound) and stiffness varied with the three orthogonal directions, the highest significance being between the proximo-distal (PD) and antero-posterior (AP) directions (p < 0.0001 for stiffness and p = 0.0003 for velocity). Ultrasound velocity was significantly correlated with compressive bone strength (r = 0.76, p < 0.0001) and stiffness (r = 0.79-0.83, p < 0.0001). BMD was also significantly correlated with compressive strength (r = 0.82, p < 0.0001) and stiffness (r = 0.66-0.81. p < 0.001). Using multiple regression analysis both BMD and velocity were significant predictors of strength (r = 0.88, p = 0.0004 and 0.0054 respectively) and stiffness (r = 0.92, p = 0.0001 and 0.0003 respectively). BMD and velocity were still independent significant predictors of both stiffness (r = 0.93, p < 0.0001 and 0.0001 respectively) and strength (r = 0.89, p < 0.0001 and 0.02) when they were combined as a product (BMDn*Vm). This suggests that BMD measured using DXA, if used in conjunction with ultrasound velocity, may be able to improve osteoporosis risk assessment. The information about femur anisotropy may also be important for hip prosthesis and in vivo modelling.

Intestinal permeability, gastric intramucosal pH, and systemic endotoxemia in patients undergoing cardiopulmonary bypass.

OBJECTIVE: To examine the relationship between gastric intramucosal pH, intestinal permeability, endotoxemia, and oxygen delivery in patients undergoing cardiopulmonary bypass (CPB). DESIGN: Prospective, observational study. SETTING: Tertiary care center. PATIENTS: Fifty patients undergoing elective cardiac surgery and 10 patients awaiting elective cardiac surgery. INTERVENTIONS: Patients received chromium 51-labeled ethylenediaminetetraacetic acid (51Cr-EDTA) as a marker of intestinal permeability; insertion of a nasogastric tonometer to measure intramucosal pH (pHi); insertion of a pulmonary artery catheter to measure systemic oxygen delivery and consumption variables; arterial blood sampling for plasma endotoxin by the Limulus amebocyte lysate assay; and blood and urine sampling for measurement of 51Cr-EDTA. MAIN OUTCOME MEASURES: Systemic oxygen delivery, duration of gastric mucosal acidosis, absorption of 51Cr-EDTA, appearance of systemic endotoxemia, renal dysfunction, and duration of hospital stay. RESULTS: Median (range) 24-hour urinary recovery of 51Cr-EDTA in patients was 10.6% (2.1% to 40.2%) while that in controls was 1.2% (0.7% to 2.0%, P<.001). Intestinal permeability increased during CPB. The median (range) for the lowest pHi after bypass was 6.98 (6.74 to 7.17). The pHi did not decline until CPB was discontinued and the heart took over the load of the circulation. Endotoxin was detectable (>0.2 endotoxin unit per milliliter) in the plasma of 21 patients (42%) during the study, most of whom were endotoxemic by the end of CPB. There was no evident relationship between the degree of gut permeability, endotoxemia, gut ischemia, or systemic oxygen dynamics. CONCLUSIONS: Cardiopulmonary bypass is associated with increases in gut permeability, which precede gut mucosal ischemia. In cardiac surgical patients, a low pHi is not necessarily indicative of an adverse clinical outcome. Endotoxemia as measured by the Limulus amebocyte lysate assay is common. The increased intestinal absorption of 51Cr-EDTA and gastric mucosal acidosis occur as independent phenomena and are not related in severity or time of onset.

Radiological assessment of a new bone densitometer--the Lunar EXPERT.

Dual energy X-ray absorptiometry (DXA) is one of the most widely used techniques in the management of osteoporosis and other skeletal diseases. Although patient doses from DXA are generally low, it is still necessary to measure them to assess the risk of radiation injury. We report on a study to estimate the effective dose (ED) to patients and staff from a new DXA scanner--the Lunar EXPERT, and make a comparison with a similar study carried out on a Lunar DPX-L. The entrance surface doses were measured to be 895 microGy and 10.25 microGy for the EXPERT and DPX-L, respectively. The EXPERT maximum EDs were calculated to be 74.7 microSv and 44.9 microSv for the anteroposterior (AP) lumbar spine and the proximal femur, respectively. More than 50% reduction in ED could be achieved by using a smaller scanning width. The maximum EDs for the DPX-L were calculated to be 0.21 microSv and 0.15 microSv for the AP lumbar spine and the proximal femur, respectively. The scattered dose rates (ambient dose equivalent) were measured to be less than 2 and less than 1 microSv h-1 at 50 cm and 100 cm, respectively, for the DPX-L, and the equivalent values for the EXPERT were 240 and 64 microSv h-1. Although both the patient dose and scattered dose rates are quite low relative to other radiological examinations, good practice aimed at dose reduction should still be implemented. Whilst protection for the operator is not needed for the DPX-L system, it may be (depending on the size of the room) for the EXPERT system.