O31 Central venous access in ventilated COVID-19 patients: a vascular surgery perspective

Introduction

The number of patients on intensive care units (ICU) increased manifold during the initial COVID-19 surge and medical staff were relocated to help compensate. The need for central venous catheters (CVCs) increased accordingly and comprised a significant workload under challenging circumstances. Several models were proposed to manage the lines. We assigned a vascular team of vascular surgeons and interventional radiologists for CVCs in ICU. We report on the workload, outcomes and lessons learned.

Method

50 consecutive ventilated COVID-19 patients in ICU (median age 63 years, 80% male) who had a CVC inserted by the vascular team from March to May 2020 were assessed. Median follow up was 18 days (range 14– 29 days) after ICU admission.

Result

166 CVCs (80 VasCaths) were inserted. Femoral access was preferred. Each patient required a median of 3 lines (IQR 2–4). CVCs were exchanged after median 7 days (IQR 4–9) for thrombosis (35%), infection (24%) or prophylactically (41%). Our learning curve included the establishment of an online referral pathway, CVC teams of two operators, extended disposable CVC kits and ICU based ultrasound scanners. Additional staffing and retraining were avoided. There were no technical complications.

Conclusion

Ventilated COVID-19 patients require multiple CVCs which is a challenging workload during a pandemic. Vascular surgeons and interventional radiologists with endovascular skills are well positioned to perform central venous cannulation to alleviate the burden on critical care teams. Our lessons learned can help to provide a safe and efficient model amidst the ongoing national outbreaks.

Take-home Message

With the postponement of many elective vascular procedures during the pandemic crisis, the involvement of vascular surgeons in a dedicated Lines team is an important way that they can contribute given their proficiency with wires and cannulation equipment, as well as familiarity in femoral triangle and jugular anatomy. The retraining of staff and additional on-call rotas can then be avoided.

Potential role for vascular surgeons during a COVID-19 outbreak: management, workload, and outcomes from the initiation of a central venous line service for patients with COVID-19 undergoing ventilation during the initial UK peak

This is a report by a vascular unit in London on the initiation of a central venous line service for patients with COVID-19 undergoing ventilation during the initial UK peak. It includes views on management, workload, and overall outcomes.

The challenge of differentiating vaso-occlusive crises from osteomyelitis in children with sickle cell disease and bone pain: A 15-year retrospective review

PURPOSE

The paediatric sickle cell disease (SCD) osteomyelitis (OM) incidence is 0.3% to 12%. Differentiating vaso-occlusive crises (VOC) from OM is a diagnostic challenge, with limited evidence guiding management. We present a 15-year review of a paediatric sickle cell cohort. We aim to identify OM incidence and provide a management protocol for these children presenting with bone pain.

METHODS

A prospective database of children with haemoglobinopathies (2002 to 2017) was analyzed for temperature, C-reactive protein (CRP) and white cell count (WCC) on admission as well as imaging, treatment and cultures. OM diagnosis was supported by imaging and blood cultures. VOC was defined as bone pain that improved without antibiotics.

RESULTS

Over 15 years, 96 children with SCD presented 358 times to hospital. Empirical antibiotics were given in 308 presentations. There were five cases of OM (1.4%); two acute and three chronic. In all, 50 presentations of VOC were identified. No significant differences in age were noted between the OM and VOC group. Temperature and CRP were significantly elevated in the OM group with no significant difference in WCC. Cultures were only positive in the chronic OM admissions. There were no cases of septic arthritis. No surgical intervention was required.

CONCLUSION

In children with SCD presenting with persistent bone pain, fever, elevated CRP and WCC, OM should be suspected and prompt antibiotic treatment started. Our treatment pathway was successful avoiding OM in 98.6% and septic arthritis in 100%. Further research on novel biological markers distinguishing OM from VOC should be investigated.

LEVEL OF EVIDENCE

III.

Fluorescence microscopy image noise reduction using a stochastically-connected random field model

Fluorescence microscopy is an essential part of a biologist’s toolkit, allowing assaying of many parameters like subcellular localization of proteins, changes in cytoskeletal dynamics, protein-protein interactions, and the concentration of specific cellular ions. A fundamental challenge with using fluorescence microscopy is the presence of noise. This study introduces a novel approach to reducing noise in fluorescence microscopy images. The noise reduction problem is posed as a Maximum A Posteriori estimation problem, and solved using a novel random field model called stochastically-connected random field (SRF), which combines random graph and field theory. Experimental results using synthetic and real fluorescence microscopy data show the proposed approach achieving strong noise reduction performance when compared to several other noise reduction algorithms, using quantitative metrics. The proposed SRF approach was able to achieve strong performance in terms of signal-to-noise ratio in the synthetic results, high signal to noise ratio and contrast to noise ratio in the real fluorescence microscopy data results, and was able to maintain cell structure and subtle details while reducing background and intra-cellular noise.

Post operative complications in a dedicated elective orthopaedic hospital: transfers requiring specialist critical care support

We aim to report our experience with out of hospital transfers for postoperative complications in a stand-alone elective orthopaedic hospital. We aim to describe the cohort of patients transferred, the rate of transfer and assess the risk factors for transfer. Patients were identified who were transferred out of the hospital to another acute hospital for management of non-routine medical problems. Patient data was collected relating to age, BMI, ASA, type of surgery, nature of the complication, timing and the outcome of transfer. In 2012, 2,853 inpatient surgical procedures were carried out, 51 patients (1.8%) developed a postoperative complication that required out of hospital transfer. Mean age of patients transferred was 67 (12-86) years, mean age of the overall case mix 58 years (0-96) (p = 0.01). 37.7% of the overall case mix of surgeries was made up of primary hip and knee arthroplasty procedures, these patients made up 63.7% of patients transferred out (p = 0.001). Mean BMI recorded was 31.7 (22-48) compared to the mean BMI of the total arthroplasty case mix of 28.8 (20-44) (p = 0.02). 59% of all patients at our institution were ASA category II or III. 76% of patients transferred were ASA category II or III (p = 0.005). We can conclude that patients requiring transfer are typically older. Arthroplasty patients are more likely to require transfer than patients undergoing other orthopaedic procedures. Among the arthroplasty cohort transferred patients will typically have a higher BMI than average. Patients with ASA category II or III make up nearly three quarters of those patients transferred. The mean age of patients transferred is typically older by 9 years.

Pelvic and acetabular fractures

Patients that sustain pelvic and/or acetabular trauma in Ireland and require surgical intervention are treated at the Adelaide and Meath National Children's Hospital (AMNCH). For this study an audit was conducted of all pelvic and acetabular fractures referred to the AMNCH over a 12 month period from July 2010 to June 2011. This study was conducted with the purpose of recording the different fracture patterns, methods of injury and surgical procedures performed over this time frame. The results demonstrate that 109 patients were referred to the AMNCH with the majority of these fractures being sustained as the result of an RTA (43) or a fall from a height (45). Seventy one patients suffered an acetabular fracture while 43 patients suffered a fracture of their pelvic ring with some patients suffering both. There were 129 surgical procedures performed with 25 patients having more than one surgical procedure.

Comparison between terminal slope rate constant and "slope/intercept" as measures of glomerular filtration rate using the single-compartment simplification

Several whole-body variables are available for indexing glomerular filtration rate (GFR), including extracellular fluid volume (ECF volume, ECV), which has the advantage that GFR based only on the terminal exponential, alpha 2, of the chromium-51 ethylene diamine tetraacetic acid (51Cr-EDTA) plasma clearance curve is a measure already indexed for ECV. This slope-only method, however, is open to the theoretical criticism of a lack of robustness not present in the more conventional slope/intercept method, which generates GFR in absolute units before indexation to body surface area (BSA). To further evaluate the slope-only method, a large database of routine three-sample GFR measurements, based on 51Cr-EDTA, was analysed with the aim of comparing GFR/BSA with GFR/ECV, identifying the main sources of error in their respective measurements and explaining why they might be discrepant. The database was subdivided into 304 patients (group A) in whom the correlation coefficient of the fit to the three data points was greater than 0.99 and 31 patients in whom it was less than 0.99 (noisy data; group B). There was modest agreement between GFR/BSA and GFR/ECV in group A (r = 0.77; mean ratio 1.01 +/- 0.21). The difference between them correlated significantly with BSA (r = 0.52; P < 0.001), as would be expected given that small individuals have a relatively high BSA. Subdividing group A into four subgroups stratified according to BSA led to a slight improvement in the correlation between GFR/BSA and GFR/ECV. Because an error in alpha 2 is balanced by an opposing error in the intercept (which leads to a change in distribution volume in the opposite direction), and therefore impacts on both GFR/BSA and GFR/ECV, whereas an error in administered dose affects only GFR/BSA, it is possible to evaluate such errors by examining the respective relationships of GFR/BSA and GFR/ECV with indexed ECV. In group A, GFR/BSA correlated positively with ECV/1.73 m2, not surprisingly as ECV/BSA is effectively the ratio GFR/BSA to GFR/ECV, while GFR/ECV correlated negatively with ECV/1.73 m2. This implies that errors other than alpha 2, probably principally in administered dose, were as important as errors in alpha 2. This conclusion was supported by disappearance of the positive correlation between GFR/BSA and ECV/BSA in group B, brought about by the greater errors in alpha 2 in this group. This study suggests that, because of the effects of errors in the slope/intercept method that do not affect alpha 2, GFR based on slope only is at least as robust as that based on slope/intercept.

Indexed glomerular filtration rate as a function of age and body size

The conventional way in which to scale or index a measurement of glomerular filtration rate (GFR) is to express it in relation to body surface area (BSA). However, BSA may not be appropriate for infants and children because, as individuals increase in size, their relative BSA decreases. Several other whole-body variables have been suggested as alternatives, including extracellular fluid volume (vECF). The purpose of the present study was to compare BSA and vECF as variables against which to index GFR, and in particular to look at this comparison in children versus adults. A total of 130 patients (age range 1-80 years; 40 patients <12 years) undergoing clinically indicated routine measurement of GFR using the bolus-injection single-compartment technique were included in the study. GFR was measured as the plasma clearance of [(51)Cr]EDTA as assessed from three peripheral venous blood samples taken between 2 and 4 h after injection of [(51)Cr]EDTA. Volume of distribution (V(d)) was obtained by extrapolation of the clearance curve to zero time. GFR was scaled to a BSA of 1.73 m(2). GFR and GFR/1.73 m(2) were corrected to account for the assumption of a single compartment. The rate constant of the exponential between 2 and 4 h was also corrected to give GFR/litre ECF. GFR and GFR/1.73 m(2) were both divided by GFR/litre ECF, to give vECF and vECF/1.73 m(2) respectively. Weight per unit BSA increases as a linear function of BSA. vECF is always less than V(d), on average by about 30%. vECF increased as an exponential function of BSA and as a linear function of body weight. vECF/70 kg body weight was higher in children (16. 2+/-3 litres) than adults (13.4+/-2.3 litres), but vECF/1.73 m(2) was lower in children (9.7+/-1.7 litres) compared with adults (12. 4+/-2 litres). vECV/1.73 m(2) increased as a function of both age and BSA, but vECF/kg decreased. GFR/12.5 litres vECF was higher than GFR/1.73 m(2) in children, but these values were similar in adults, with the ratio of these two forms of indexed GFR falling significantly with both age and BSA. Although this was not a normal population, but one with a wide range of renal function, GFR/vECF showed a strong inverse association with age, whereas for GFR/BSA the association was weak. In conclusion, these data provide further evidence that vECF is more valid physiologically for indexing GFR than is BSA, especially in children. Nevertheless, a GFR measurement in a child should ideally be expressed as a percentage of normal for that child's age. However, such normal values are not yet available.

Double blind glucocorticoid controlled trial of samarium-153 particulate hydroxyapatite radiation synovectomy for chronic knee synovitis

BACKGROUND

Samarium-153 particulate hydroxyapatite (Sm-153 PHYP) is a relatively new radiation synovectomy agent developed for the treatment of chronic synovitis. Although it has been shown that the levels of unwanted extra-articular radiation are lower after intra-articular injection of Sm-153 PHYP than yttrium-90 colloid, its clinical efficacy has not been rigorously studied.

OBJECTIVES

To establish whether Sm-153 PHYP radiation synovectomy results in a clinically useful benefit sustained at one year.

METHODS

In a randomised double blind study, patients received either intra-articular 40 mg triamcinolone hexacetonide alone or 40 mg triamcinolone hexacetonide combined with Sm-153 PHYP in an outpatient clinic.

RESULTS

Sixty patients (28 male, 32 female), median age 51 (18-75) with chronic knee synovitis were studied. Diagnoses included: rheumatoid arthritis (n=29); psoriatic arthritis (n=9); ankylosing spondylitis (n=3); reactive arthritis (n=2); undifferentiated seronegative oligoarthritis (n=13) and miscellaneous inflammatory conditions (n=4). More patients who received Sm-153 PHYP/triamcinolone hexacetonide sustained clinical benefit a year after treatment compared with patients who received corticosteroid alone (12 of 31 (39%) v 6 of 29 (21%), a difference of 18% more patients (95% CI -5% to 41%)) though the difference was not significant (chi(2)=2.31, 0.2>p>0.1, n=60). Despite the variation in injected activity (median 563 MBq, range 218-840 MBq), there was no obvious relation between low levels of injected activity (<555 MBq) and relapse within 12 months of treatment (chi(2) =2.61, 0.2>p>0.1, n=31).

CONCLUSIONS

There was no clear beneficial clinical effect of combined Sm-153 PHYP/triamcinolone hexacetonide injection over triamcinolone hexacetonide alone a year after treatment for chronic knee synovitis.

Appropriate corrections to glomerular filtration rate and volume of distribution based on the bolus injection and single-compartment technique

The bolus injection, single-compartment technique for measuring GFR overestimates the true value. Nevertheless, assuming that for a given indicator the area under the first exponential of the plasma clearance curve is constant from subject to subject, the observed (uncorrected) value can be corrected by multiplication with a 'sliding' factor, the value of which is a nonlinear function of GFR. Several second-order polynomials, based on pre-determined relationships between simultaneously determined two-compartment and one-compartment GFR, have been described for correcting GFR (GFR correction). It is, however, theoretically more rational to use a factor which depends on the rate constant, alpha2, of the terminal exponential of the clearance curve. We have therefore determined a set of linear equations from retrospectively analysed multiple-sample inulin, 99mTc-DTPA and 51Cr-EDTA clearance curves to enable correction of GFR using alpha2. A set of linear equations is also developed to correct the volume of distribution (Vd) of the indicator (close to extracellular fluid volume for these indicators), which is also overestimated by the one-compartment technique. At low levels of GFR, alpha2-corrected GFR is similar to uncorrected GFR for all three indicators. As GFR increases, however, uncorrected GFR progressively overestimates (alpha2-corrected GFR. The overestimation is greater for inulin than for 99mTc-DTPA or 51Cr-EDTA. In the one-compartment approximation, Vd is overestimated more than GFR, and again the greatest overestimation is seen with inulin. In a prospective study of 129 patients undergoing routine measurement of GFR with 51Cr-EDTA, alpha2 correction using a factor based on retrospective EDTA data gave values of GFR which were higher than values obtained from GFR correction using a previously published polynomial (also based on EDTA clearances) by 15% in children and 12.5% in adults when uncorrected GFR was 150 ml/min/1.73 m2. Moreover, the ratio of uncorrected GFR to GFR-corrected GFR was higher in children than adults. We conclude that alpha2 is a more rational variable with which to correct two-sample or three-sample GFR than GFR itself, that the correction formulae are not interchangeable between inulin on the one hand and EDTA and DTPA on the other, and that the relative magnitudes of the corrections given by alpha2 correction versus GFR correction are different for children and adults.

Changes in articular synovial lining volume measured by magnetic resonance in a randomized, double-blind, controlled trial of intra-articular samarium-153 particulate hydroxyapatite for chronic knee synovitis

OBJECTIVE

Magnetic resonance techniques have recently been investigated as tools with which to monitor inflammatory joint disease. Our aim was to use a contrast-enhanced T1-weighted protocol to monitor the short-term changes in knee synovial lining volume in a double-blind, randomized, controlled trial of intra-articular samarium-153 particulate hydroxyapatite (Sm-153 PHYP).

METHODS

Twenty-four out-patients with chronic knee synovitis, from a cohort who had been recruited to a long-term clinical efficacy trial, were recruited for this study. Patients received either intra-articular Sm-153 PHYP combined with 40 mg triamcinolone hexacetonide or 40 mg intra-articular triamcinolone hexacetonide alone. Synovial lining volumes were calculated from three-dimensional T1-weighted contrast-enhanced images made before and after contrast enhancement with thresholding and pixel counting, immediately before and 3 months after treatment.

RESULTS

Paired pre- and post-treatment magnetic resonance data were obtained for 18/24 (75%) patients. There was no significant difference in mean pre-treatment synovial volume between the two treatment groups (139 vs 127 ml). A mean reduction in synovial lining volume was detected in the Sm-153 PHYP/steroid-treated group (139 to 110 ml, P = 0.07) and in the steroid-treated group (127 to 58 ml, P < 0.001). The reduction was significantly greater in the steroid-treated group (-61% vs -23%, P < 0.05).

CONCLUSIONS

Short-term changes in articular synovial lining in response to intra-articular treatment for chronic synovitis may be monitored by magnetic resonance imaging. After 3 months, a greater mean reduction in synovial lining volume had occurred in response to intra-articular steroid alone compared to combined Sm-153 PHYP/steroid injection.

Bisindolylmaleimide VIII facilitates Fas-mediated apoptosis and inhibits T cell-mediated autoimmune diseases

Fas-mediated apoptosis is essential for the elimination of cells, and impaired apoptosis can have severe detrimental consequences. Bisindolylmaleimide VIII potentiated Fas-mediated apoptosis in human astrocytoma 1321N1 cells and in Molt-4T cells, both of which were devoid of apoptosis induced by anti-Fas antibody in the absence of bisindolylmaleimide VIII, and in Jurkat and CEM-6 T cells, which showed slight and moderate apoptotic responses, respectively, to low levels of Fas stimulation. Potentiation of Fas-mediated apoptosis by bisindolylmaleimide VIII was selective for activated, rather than non-activated, T cells, and was Fas-dependent, as it was not observed in T cells from Fas-deficient lpr/lpr mice. Administration of bisindolylmaleimide VIII to rats during autoantigen stimulation prevented the development of symptoms of T cell-mediated autoimmune diseases in two models, the Lewis rat model of experimental allergic encephalitis and the Lewis adjuvant arthritis model. Thus, the use of agents such as bisindolylmaleimide VIII may be therapeutically useful for supporting more effective elimination of detrimental cells through enhancement of Fas-dependent apoptosis signaling.

Early detection of melanoma metastases with radioiodinated methylene blue

Melanin synthesised in melanoma cells presents a unique target to which the treatment can be selectively addressed, provided the pigment is recognised by a suitable drug. Methylene blue (MTB) possesses a high affinity for melanin and, therefore, accumulates preferentially in melanoma cells. Since not directly toxic to the tumour, MTB serves as a carrier for radioisotopes and, once taken up by melanoma cells, acts as a selectively localised source of radiation. Hence, radioderivatives of the compound can be used for both diagnosis and therapy of disseminated melanoma. Eleven patients with confirmed metastatic melanoma and one with a recent local recurrence were studied using radioiodinated (iodine-123 or iodine-131) MTB and a gamma camera. Biopsies of cutaneous lesions were taken to determine directly the compound uptake in tumours. This first clinical investigation concerning the diagnostic potential of radioiodinated MTB in patients with disseminated melanoma confirmed the existence of approximately 80% of internal lesions previously identified by routine methods and, additionally, enabled detection of unknown secondaries in 6 of 12 patients studied. There were no false-positive gamma camera images regardless of whether 123I or 131I was used. 131I proved to be more suitable than 123I for detecting melanoma metastases with radioiodinated MTB. Hazy images of the lesions treated with external beam radiation and/or some drugs suggest that initial radio- and chemotherapy might affect MTB uptake in melanoma metastases and reduce the clarity of the scintigrams obtained from a gamma camera. However, small, untreated internal lesions that cannot be visualised easily with the standard diagnostic methods are revealed with 131I-MTB regardless of their localisation. It is concluded that use of radioiodinated MTB in conjunction with gamma camera or positron emission tomographic imaging might prove to be a useful and accessible tool for the detection of early melanoma dissemination.

[Dynamics of local cerebral blood flow in different somatosensory cortical layers during whisker stimulation in rats]

Whisker stimulation in rats was found to increase the local cerebral blood flow (lCBF), its SD and to damp slow oscillations. It was established that lCBF drops slightly within a few seconds after the stimulus onset. The data obtained suggest that lCBF evoked sensory stimulation changes are distinctly localized in different layers of the somatosensory cortex.

Initial evaluation of 123I-5-I-R91150, a selective 5-HT2A ligand for single-photon emission tomography, in healthy human subjects

The mapping of 5-HT2 receptors in the brain using functional imaging techniques has been limited by a relative lack of selective radioligands. Iodine-123 labelled 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-io do-2-methoxybenzamide (123I-5-I-R91150 or 123I-R93274) is a new ligand for single-photon emission tomography (SPET), with high affinity and selectivity for 5-HT2A receptors. This study reports on preliminary 123I-5-I-R91150 SPET, whole-body and blood distribution findings in five healthy human volunteers. Maximal brain uptake was approximately 2% of total body counts at 180 min post injection (p.i. ). Dynamic SPET sequences were acquired with the brain-dedicated, single-slice multi-detector system SME-810 over 200 min p.i. Early peak uptake (at 5 min p.i.) was seen in the cerebellum, a region free from 5HT2A receptors. In contrast, radioligand binding in the frontal cortex increased steadily over time, up to a peak at approximately 100-120 min p.i. Frontal cortex-cerebellum activity ratios reached values of 1.4, and remained stable from approximately 100 min p.i. onwards. Multi-slice SPET sequences showed a pattern of regional variation of binding compatible with the autoradiographic data on the distribution of 5-HT2A receptors in humans (cerebral cortex>striatum>cerebellum). These findings suggest that 123I-5-I-R91150 may be used for the imaging of 5-HT2A receptors in the living human brain with SPET.

MR imaging of tibial plateau fractures

Magnetic resonance (MR) images of five patients with acute tibial plateau fractures are presented and correlated with both clinical examination and findings at surgical intervention. The role of MR imaging in the evaluation of both osseous and soft tissue deformity in acute trauma, specifically in patients with tibial plateau fractures is discussed. The value of MR imaging as an alternative to computed tomography and arthroscopic evaluation of these patients is emphasized.

The significance of increased 111indium platelet accumulation at post-angioplasty sites

We assessed prospectively the significance of 111indium labelled platelet accumulation following angioplasty procedures in 12 patients (9 femoral angioplasties (2 laser, 1 atherectomy) and 3 iliac stents). Autologous 111indium labelled platelets were re-injected immediately after angioplasty. Radioactivity was measured over treated and reference sites, by single probe and gamma camera, and expressed as a radioactivity ratio (RR). All patients had duplex ultrasound assessment and occlusions were confirmed by arteriography. RR was always raised after angioplasty. Three patients who had acute occlusions showed markedly raised average RRs (significant at 99% ANOVA). RR was not raised after laser assisted angioplasty, however, our numbers were small. 111Indium platelet radioactivity did not predict subsequent occlusion after angioplasty but effectively detected existing acute post-angioplasty occlusions.

Targeting disseminated melanoma with radiolabelled methylene blue: Comparative bio-distribution studies in man and animals

Targeted radiotherapy for pigmented melanoma with 3,7-(dimethylamino) phenazathionium chloride [methylene blue (MTB)] labelled with Astatine-211 (211At; alpha-particle emitter) proved to be very effective in animal model systems. Since the results justified an introduction of the treatment to the clinic, the aim of the bio-distribution studies using [123I]-MTB and [131I]-MTB in patients was to confirm selectiveness of radiolabelled MTB uptake in melanoma lesions. The investigations were carried out using planar and SPECT (single photon emission computed tomography) gamma-cameras. A stable uptake of radioiodinated MTB was found in pigmented melanomas in man, with tumour/surrounding tissue and tumour/blood ratios amounting to 9 at 19 h after a single i.v. injection. A time-dependent kinetics of radioiodinated MTB distribution was similar to that observed in human melanoma-bearing athymic mice. Blood radioactivity decreased by about 90% during the first 2.5 min after i.v. injection of the compound (T1/2biol = 0.58 min). Its retention time in various organs was either the same or very similar to that characteristic of the blood. A rapid uptake of radioiodinated MTB in the liver and kidneys confirmed the importance of these organs in excreting the compound: 25-30% of the radioactivity administered was expelled with urine over the first 24 h after the injection. There was no obvious retention of radioiodinated MTB in the brain over the observation period and in the eyes for at least the first 14 h.

Clinical outcome after one year following samarium-153 particulate hydroxyapatite radiation synovectomy

The clinical outcome and tolerability following treatment with samarium-153 particulate hydroxyapatite was evaluated in patients with persistent rheumatoid knee synovitis. The clinical review of 18 patients treated with intra-articular samarium-153 particulate hydroxyapatite combined with triamcinolone hexacetonide who had failed to obtain more than 4 weeks symptom relief from a prior intra-articular glucocorticoid injection was undertaken. No unwanted effects from the treatment were observed. Symptom relief was maintained in 56% patients at 6 months and in 44% of patients at 12 months following treatment. Median duration of symptom relief was 9 months. There was a significantly higher mean baseline Ritchie Articular Index in patients relapsing within 3 months and a trend towards earlier relapse in patients with higher indices of disease activity at the time of treatment. There was a trend towards earlier relapse in patients with a poor range of knee flexion at baseline and with worse indices of intra-articular radiopharmaceutical distribution. Samarium-153 particulate hydroxyapatite knee synovectomy is well tolerated and may be an effective treatment for carefully selected patients with persistent rheumatoid knee synovitis.

CT findings of malignant change in recurrent respiratory papillomatosis

Recurrent respiratory papillomatosis is a chronic disease of children and young adults associated with various complications, one of which is malignant change. We report CT findings of malignant change in a case of recurrent respiratory papillomatosis.

Technetium-99m-L,L-ethylenedicysteine scintigraphy in patients with renal disorders

Technetium-99m-L,L-ethylenedicysteine (99mTc-L,L-EC), a new renal imaging agent, was introduced as an alternative to 99mTc-mercaptoacetyltriglycine (MAG3). This radiopharmaceutical can be easily labelled at room temperature and has high radiochemical purity and long stability. The aim of this study was to gain clinical experience in using 99mTc-L,L-EC in normal volunteers and patients. The clearance of this radiopharmaceutical was compared with that of iodine-131 ortho-iodohippurate (OIH) in five healthy volunteers. In addition, conventional renogram and whole-body distribution of 99mTc-L,L-EC (40 min and 3 h post-injection) were evaluated in these subjects. Subsequently, ten patients with suspected obstructive nephropathy, four with renovascular disorders and two in acute renal failure were imaged. In five patients with impaired renal function both 99mTc-MAG3 and 99mTc-L,L-EC studies were performed. In each case the scintigraphic images and time/activity curves were evaluated and various semiquantitative parameters calculated and compared. No adverse effects were noted during and after 99mTc-L,L-EC scintigraphy. The mean clearance values for 99mTc-L,L-EC and 131I-OIH in volunteers were 504 and 663 ml/min respectively. The total plasma clearance of 99mTc-L,L-EC was about 75.8% of the 131I-OIH value. In volunteers the parenchymal transit time index, whole kidney transit time index and mean parenchymal transit time for 99mTc-L,L-EC were 63 s, 124 s and 175 s respectively. The mean time to peak activity was 235 s and the time from peak to 50% of peak activity was 402 s.(ABSTRACT TRUNCATED AT 250 WORDS)

Samarium-153-particulate hydroxyapatite radiation synovectomy: biodistribution data for chronic knee synovitis

Biodistribution data for the radiation synovectomy agent samarium-153-particulate hydroxyapatite (153Sm-PHYP) are reported.

METHODS

Mean extra-articular activity accumulation calculated from serial whole-body scans in 13 patients treated for chronic knee synovitis was 0.74% of injected activity (range 0%-3%).

RESULTS

In four patients (31%), activity was noted in the lung (mean 0.68% of injected activity). In six patients (46%), 0.29% of injected activity accumulated in the regional lymph nodes and in three patients (23%), 0.62% of injected dose accumulated in the liver. Absorbed dose estimates were lung: 14 mGy, regional lymph nodes; 50 mGy, liver; 4 mGy. SPECT demonstrated good distribution of 153Sm-PHYP throughout the anterior knee compartments, although distribution to the posterior compartment was variable.

CONCLUSION

Distribution is dependent on adequate knee flexion immediately following injection and may be influenced by the size range of labeled particles. Favorable biodistribution data suggest that 153Sm-PHYP is a potentially useful radiation synovectomy agent.

[A comparison of the measurements of local cerebral blood flow by hydrogen clearance with hydrogen inhalation and by its electrochemical generation in brain tissue]

The goal of the present investigation was to compare data received by modifications of H2-clearance method with inhalation (H2-Inh) and electrochemical generation in brain tissue (H2-Gen) of H2 from the same recording electrodes in acute experiments (urethane 1g/kgip) with Wistar rats (n = 39). Block of three or four Pt electrochemically sharpened electrodes to tip diameters of 20-40 mu, 0.3-0.5 mm apart and 0.8-1.0 mm in length were inserted through the dura into sensorimotor cortex. One electrode was used for H2 generation (DC current 3-5 microA) and the others for PH2 recordings by polarographical method. Durations of H2 inhalation and H2 electrochemical generation were 3 or 10s with similar amplitudes of PH2. Data was recorded with a MacLab analog-digital system and Macintosh 11si computer. Recordings of resting LCBF were made with H2-Gen and H2-Inh the beginning of the experiment and after 40-60 min. LCBF was stimulated with inhalation of 7.5% CO2 for 60s. In 6 preparations LCBF was measured 10-20 min. after occlusions of two branches of the middle cerebral artery. After experiments the brain was perfused with India ink and cut in frozen sections for morphological analyses. The mean values of resting LCBF measured by H2-Inh was 1.67 +/- 0.54 ml/g/min. (+/- SD, N = 149), and by H2-Gen 3.17 +/- 0.91 (N = 147). The diffusional component was estimated as 1.2-2.5 (equivalent units, ml/g/min.) in dead cortex. The ratio of clearances in H2-Gen to H2-Inh varied in different experiments from 1.0 up to 4.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Mesenteric microcirculatory changes in nonlethal hemorrhagic shock: the role of resuscitation with balanced electrolyte or hypertonic saline/dextran

Class I and II hemorrhage has been routinely treated clinically with 2-2.5 times the volume of shed blood as balanced electrolyte solution. Although this regimen has been shown to adequately restore arterial pressure in trauma patients, it is not clear that it uniformly restores regional perfusion. Since it is becoming apparent that the gut plays a major role in the development of the posttraumatic septic state, we studied the effects of graded doses of balanced electrolyte resuscitation on the mesenteric microcirculation. Regimens consisting of one (1 x LR), two (2 x LR), or three (3 x LR) times the volume of shed blood as lactated Ringer's (LR) solution or 7.5% hypertonic saline and 6% dextran (HSD) equal to one seventh the volume of shed blood were given to groups of anesthetized (urethane-chloralose) male Sprague-Dawley rats after 30 minutes of hemorrhage to 50% of baseline mean arterial blood pressure. The microcirculation of the distal ileum was observed using an in vivo video microscope. Mean arterial pressure and ileal A1 diameters returned to baseline values with HSD within 20 minutes following this moderate hemorrhage. Additionally, A1 diameters returned to baseline in the 2 x LR and 3 x LR groups. A1 vessels remained significantly constricted in the 1 x LR group. Mean arterial pressure remained significantly lower than the baseline value in all of the LR groups. We conclude that in this model, HSD is superior to LR for restoration of blood pressure. In restoring A1 diameters, LR is equivalent to HSD only when volumes of balanced electrolyte two and three times shed blood volume are given.

Combined 67Ga citrate and 99Tcm-human immunoglobulin imaging in human immunodeficiency virus-positive patients with fever of undetermined origin

Patients infected with the human immunodeficiency virus (HIV) suffer from serious and life-threatening infections. These patients often present with pyrexia but without localizing signs. Despite its high sensitivity in identifying focal infection 67Ga citrate scintigraphy lacks specificity; lymphoma and solid tumours may also be imaged. This presents particular problems in HIV-positive patients with pyrexia where the differential diagnosis is often between infection and lymphoma. In an attempt to improve the specificity of radionuclide imaging in these patients a combination of 67Ga citrate and the new agent 99Tcm-labelled human immunoglobulin (99Tcm-HIG) was used in 25 patients who were sequentially imaged with the two agents. Fourteen patients had 29 sites of microbiologically confirmed infection; 67Ga citrate identified 27 sites and 99Tcm-HIG identified 16 sites. Seven of the nine sites visualized with 99Tcm-HIG, but positive with 67Ga citrate, were intrathoracic. Abnormal concentration of 67Ga citrate, not due to infection, occurred at eight sites; five lymphoma, one gout, one recent fracture and one patient with prominent bone marrow islands. 99Tcm-HIG showed increased concentration of tracer in only one of the patients with lymphoma. A combination of 67Ga citrate and 99Tcm-HIG imaging in HIV-positive patients with pyrexia of unknown origin enables a differentiation between infection and lymphoma to be made more readily. The poor sensitivity of 99Tcm-HIG in the chest will limit its sole use in this patient group.

The APE nebuliser--a new delivery system for the alveolar targeting of particulate technetium 99m diethylene triamine penta-acetic acid

We report the validation of a new delivery system--aerosol production equipment (known by the acronym APE), which generates a particulate aerosol of technetium 99m diethylene triamine penta-acetic acid (DTPA) with a mass-median aerodynamic diameter of 0.35 microns and a geometric standard deviation of 1.8 Twenty subjects were studied; in group 1 were 12 healthy men with normal spirometry; in group 2 were 8 men with AIDS who had mildly abnormal lung function following an episode of pneumocystis pneumonia-spirometry FEV1 3.08 (0.73) L, FVC 4.83 (0.82) L [mean (SD)]. The APE nebulizer was used to form a particulate aerosol with 200 MBq of 99mTc DTPA, which was collected in a 35 1 reservoir of air, which was subsequently inhaled. The mean (SD) inhalation time was 4.7 (0.44) min. The output of the nebulizer (% of activity inhaled) was 82%. Using planar imaging, the penetration index (right lung) in group 1 was 0.93 (0.18), mean (SD), and in group 2 it was 0.91 (0.12). There was virtually no tracheal deposition and extrapulmonary deposition (oropharynx and stomach) was less than 5% of the aerosol delivered. Single-photon emission tomography (SPET) studies carried out in five patients from group 1 confirmed homogeneous intrapulmonary deposition of 99mTc-DTPA. In view of the excellent intrapulmonary deposition of 99mTc-DTPA produced by the APE nebulizer, it may provide an alternative to conventional ventilation studies using radioactive gases.

99mTc-human immunoglobulin (HIG)--first results of a new agent for the localization of infection and inflammation

Technetium (99mTc) labelled, polyclonal human immunoglobulin (HIG) is a new agent that detects focal infection and inflammation. This new agent was compared in 40 patients with the accepted standard, namely 111In-oxine-labelled leucocytes. This comparison resulted in a sensitivity of 94% and a specificity of 96% for 99mTc-HIG when 111In-oxine leucocytes were defined as giving the true result. The new agent was shown to localize both sepsis and active inflammatory bowel disease (IBD). There was 100% concordance in the 16 patients with IBD who were imaged with both 99mTc-HIG and 111In-oxine leucocytes. Discordant results were obtained in one case of suspected osteomyelitis, which was false-positive on the 99mTc-HIG scan, and one case of pyrexia of unknown origin when the 99mTc-HIG was false-negative and the 111In-oxine leucocyte scan demonstrated accumulation of tracer in the caecum at 24 h post-injection. Normal distribution for 99mTc-HIG demonstrated activity in the kidneys and bladder and that 50% of the tracer is cleared through the kidneys during the first 24 h post-injection. There were no major or minor side-effects.

Intracellular localization of 99Tcm-d,l-HMPAO and 201Tl-DDC in rat brain

The intracellular localization and relative distribution of 99Tcm-hexamethylpropyleneamine-oxime (99Tcm-d, l-HMPAO) and 201Tl-diethyldithiocarbamate (201Tl-DDC), which have been used to assess regional cerebral blood flow (rCBF) in man, were investigated in rat brain. 99Tcm-d, l-HMPAO was found attached mainly to cell organelles whilst 201Tl-DDC was localized mainly in free state in the cytosolic fraction. Isolation of neuronal and glial nuclei showed that there is higher uptake of 99Tcm-d, l-HMPAO in neuronal nuclei than in glial nuclei for all the different regions of the rat brain investigated. These data demonstrate a different subcellular localization of the two lipophilic agents studied. In view of their proposed clinical utility, this difference merits further investigation.

White cells radiolabelled with 111In and 99Tcm--a study of relative sensitivity and in vivo viability

In this study a comparison between the classical (111In oxine) and the newer (99Tcm HMPAO) technique of labelling leucocytes is reported. The behaviour in vivo and the relative sensitivity in the detection of infection (chest and bone) and inflammatory bowel disease (IBD) is presented. Simultaneous dual-radionuclide gamma camera acquisition methodology was applied to study 99 patients, 18 with chest infection, 26 with bone infection, 41 with IBD and 14 with other pathological conditions. The mean (1 SD) 50% washout time from the lungs was 483.03 (79.10) s for 99Tcm HMPAO-labelled white blood cells and 475.85 (83.79) s for 111In oxine-labelled white cells (r = 0.81). Concordance between the two techniques was 94% in the chest-infection group of patients, 88% in the bone-infection group and 71% in the localization of IBD.

Functional imaging of the brain

The radionuclide tracer method is unique amongst all other imaging methodologies in its ability to trace organ or tissue function and metabolism. It derives this advantage from the nature of the signal used for image generation, and its single interaction with the organ or system under examination. Physical processes such as electron or proton density assessment or resonance, edge identification, electrical or ultrasonic impedence, do not pertain to the image generation process in nuclear medicine, and if so, only in a rather secondary manner. The nuclear medicine imaging study is primarily a study of the chemical nature, distribution and interaction of the tracer/radiopharmaceutical utilised with the cellular system which requires investigation: the thyroid cells with sodium iodide, the recticular endothelial cells with colloidal particles, the adrenal medulla cells with metaiodobenzylguanidine, and so on. In the two most recent areas of nuclear medicine expansion, oncology (with labelled monoclonal antibodies) and neurology and psychiatry (with a whole new series of lipid soluble radiopharmaceuticals), specific cell systems can also be targeted and hence imaged and investigated. The study of structure as masterly performed by Virchow and all his successors over more than a century, is now definitely the prerogative of such imaging systems which excel with spatial and contrast resolution (x-ray computed transmission tomography, nuclear magnetic resonance imaging, diagnostic ultrasound). However the investigation of function and metabolism (as performed by Claude Bernard, Georg von Hevesy, and so many others), has clearly passed from the laboratory animal protocol and experiment to the direct investigation in man, this being the achievement of the radionuclide tracer methodology. In this article, we review present interest and developments in that part of nuclear medicine activity which is aimed at the study of the neurological or psychiatric patient.

Contrast media osmolality and plasma volume changes

A theoretical and experimental study of the plasma volume expansion consequent on the hyperosmolality of contrast media is presented. In the case of the ratio 1.5 media theory and experiment coincide closely but in the case of the ratio 3 media the observed changes exceed the predicted. It is proposed that this is due partly to the slower diffusion of the ratio 3 media out of the intravascular space and partly due to the fact that the osmotic load presented by these media is greater than would be expected from a study of their commercial solutions in which osmolality is reduced by molecular aggregation. The implications for the relative haemodynamic effects of different contrast media are discussed. The osmotic effects of contrast media also play a part in determining the image quality achievable in intravenous digital subtraction angiography (IV-DSA). It is predicted that ratio 3 contrast media will give better quality images in IV-DSA than ratio 1.5 media.

A 99Tcm-labelled radiotracer for the investigation of cerebral vascular disease

The first clinical data is given on 99Tcm-hexamethylpropyleneamine oxime (HM-PAO) in normal subjects and patients with established stroke. Regional cerebral blood flow maps (rCBF) have been recorded and displayed in tomographic mode with this new radiopharmaceutical. Good images were obtained, comparable to those achieved with 123I-isopropylamphetamine (IMP).

The mechanism of diarrhoea resulting from pelvic and abdominal radiotherapy; a prospective study using selenium-75 labelled conjugated bile acid and cobalt-58 labelled cyanocobalamin

An attempt was made to elucidate the mechanism of diarrhoea resulting from pelvic and abdominal radiotherapy in a prospective study of 10 patients undergoing treatment for curable pelvic malignant tumours using the synthetic trihydroxy 75Se-labelled conjugated bile acid, SeHcat and 58Co-labelled cyanocobalamin (58Co Vit B12). Evidence of malabsorption of vitamin B12 measured as a significant fall in whole body percentage retention of 58Co Vit B12 from baseline levels was found in all nine patients who developed diarrhoea during radiotherapy. Only four out of these nine patients also had malabsorption of the trihydroxy conjugated bile acid, cholic acid, measured as a significant fall in SeHcat whole body percentage retention and these patients had the most severe diarrhoea. The findings are discussed in the light of what is known about the pathophysiology of diarrhoea during pelvic and abdominal radiotherapy and lend support to previous work which implicated increased bowel motility in the pathogenesis of radiation-induced diarrhoea. The hypothesis that local neuroendocrine mechanisms in the gut may be involved is put forward, with possible implications for treatment.

Cerebral blood flow studies with 123iodine-labelled amines

The cerebral distribution of a new class of 123I radiopharmaceuticals was determined by emission tomography after the isotope had been injected intravenously into 20 patients with a variety of neurological disorders. Regional cerebral blood flow images of diagnostic quality were obtained in all cases. Early and late ischaemic stroke showed up as areas of impaired perfusion, and gliomas and secondary deposits as areas of increased or reduced blood flow. A hyperaemic focus was clearly seen in an epileptic patient in whom other imaging techniques, including CT scanning and electroencephalography, had been uninformative. This new technique promises to be an extremely useful addition to the range of radioisotope brain scanning methods.

99mTc-imidodiphosphonate: a superior radio-pharmaceutical for in vivo positive myocardial infarct imaging. I: Experimental data

99mTc-Imidodiphosphonate (99mTc-IDP) was investigated as an agent for nuclear medicine imaging of acute myocardial infarctions. For this purpose a suitable animal model was found. After coronary artery ligation reproducible myocardial infarcts were obtained with 80% of surviving animals. Scans of the myocardial infarcts were recorded with a high resolution gamma camera and good quality images were obtained. 99mTc-IDP ratios for normal and infarcted tissue were calculated and compared with similar data available from other 99mTc-labelled phosphates. With an infarct/normal ratio of 21:1, 99mTc-IDP is so far the best radiopharmaceutical for nuclear medicine imaging of necrosed heart muscle. Images of the myocardial infarcts have been recorded as early as 6 hours after infarction.

High-quality, high-throughput, early whole-body bone scanning

99mTc-IDP allows for high-quality, high-throughput and early whole-body bone scanning. Whole-body bone scans obtained at 30 min after intravenous administration of the tracer were compared with the standard and delayed 180 min p.i images. A subtraction technique allowed for the anlysis of the 30 min scans and it was found that in both types of investigation the same clinical information was present. This procedure will therefore increase considerably the throughput of whole-body bone scans in a busy department of nuclear medicine. It is however inadequate for detailed analysis of the skeleton (evaluation of benign bone disease).

High-Quality, High-Throughput, Early Whole-Body Bone Scanning

99m Tc-IDP allows for high-quality, high-throughput and early whole-body bone scanning. Whole-body bone scans obtained at 30 min after intravenous administration of the tracer were compared with the standard and delayed 180 min p. i. images. A subtraction technique allowed for the analysis of the 30 min scans and it was found that in both types of investigation the same clinical information was present. This procedure will therefore increase considerably the throughput of whole-body bone scans in a busy department of nuclear medicine. It is however inadequate for detailed analysis of the skeleton (evaluation of benign bone disease).