PubMed Health⌕ Search

Biomedical subjects

C C Geddes

Publications and source records attributed to C C Geddes.

18 recordsLinked to original sources
PubMed2006

The relationship between serum creatinine and estimated glomerular filtration rate: implications for clinical practice.

INTRODUCTION: A new classification of chronic kidney disease (CKD) has been widely adopted that stratifies patients into 5 'stages' according to estimated glomerular filtration rate (eGFR). In adults the most commonly used formulae to calculate eGFR are the Cockcroft and Gault (C and G) and Modification of Diet in Renal Disease (MDRD) formulae. The UK Renal Association has recommended calculation of MDRD eGFR to screen for reduced kidney function in primary and secondary care. AIM: The aim of this study was to explore the implication of using these predictive formulae. METHODS: We searched for patients currently attending a renal clinic who have ever had a serum creatinine (SCr) of exactly 100 micromol/L, 150 micromol/L or 200 micromol/L. The C and G and MDRD eGFRs corresponding to that SCr were calculated. The proportion of patients in each stage of the CKD classification was determined. RESULTS: For a SCr of 100 micromol/L mean eGFR was 86.5 ml/min (range 31.0 - 192.8) by C and G and 63.8 ml/min (range 39.7 - 99.9) by MDRD (p < 0.0001; t-test of mean). For SCr 150 micromol/L mean eGFR was 51.7 ml/min (18.0 - 110.4) by C and G and 38.0 ml/min (20.7 - 54.8) by MDRD (p < 0.0001). For SCr of 200 micromol/L mean eGFR was 34.4 ml/min (12.6 - 89.5) by C and G and 27.3 ml/min (16.7 - 41.3) by MDRD (p < 0.0001). Using MDRD eGFR 46.5% patients with a SCr of 100 micromol/L have stage 3 CKD (GFR 30-60 ml/min) and all patients with a SCr of 150 micromol/L or 200 micromol/L have CKD 3 or worse. 8.6% of males with SCr 100 micromol/L had stage 3 CKD or worse compared with 86.8% females. 70.2% patients > 65 years old with SCr 100 micromol/L had stage 3 CKD. CONCLUSIONS: Targeted screening of patients at-risk for CKD will identify a large number of patients who require management of CKD and potential referral to nephrology services even at levels of SCr regarded as 'normal' or mildly.

Aged↗
PubMed2005

Assessing the utility of the stop dialysate flow method in patients receiving haemodiafiltration.

BACKGROUND: The stop dialysate flow (SDF) method of post-dialysis urea sampling is the most commonly used method in the UK. It can also be used with a published formula to predict 30 min equilibrated urea accurately. The method has not been validated in patients undergoing haemodiafiltration (HDF). Given the increased use of HDF across Europe, we felt it prudent to assess the utility of the SDF method and prediction equation in this modality. METHODS: Fourteen patients from two renal units were studied. Blood samples were taken at 1 min intervals from the arterial side of the dialysis circuit in the first 5 min after HDF had ceased whilst blood circulation continued. A peripheral sample was taken from the contralateral arm immediately after HDF had ceased and a 30 min sample was taken from the arterial needle. These samples were used to assess the utility of 5 min arterial blood urea and the 30 min prediction formula, respectively. RESULTS: Blood urea measured from the arterial circuit at 5 min correlated closely with the contralateral sample taken immediately post-HDF, with no significant difference (6.45+/-2.11 vs 6.52+/-2.19 mmol/l, P = 0.39). The use of 5 min arterial blood urea and prediction formula allowed an accurate prediction of 30 min urea (R2 = 0.96). CONCLUSIONS: The use of the SDF method with a 5 min post-HDF arterial sample is valid in patients receiving HDF. The previously published prediction formula for estimating 30 min urea is also valid using the 5 min post-HDF sample.

Biomarkers↗
PubMed2005

Hypertension, antihypertensive agents and outcomes following renal transplantation.

UNLABELLED: Hypertension is common following renal transplantation and adversely affects graft and patient survival. However, strategies for antihypertensive drug therapy and target blood pressure have not been clearly defined. AIM: To assess the influence of achieved blood pressure and antihypertension drug therapy on graft and patient survival with the aim of identifying targets and event rates for future intervention studies. METHODS: We undertook a longitudinal follow up study of 634 renal transplant patients. Patients were surveyed in December 1994 and followed up after 102 months. Blood pressure (BP) was determined from the mean of three clinic readings and antihypertensive drug therapy recorded. RESULTS: Complete follow up data were available for analysis on 622 patients (57.2% male; mean age: 45.2 +/- 13.0 yr. There were 158 (25.4%) deaths and 115 (18.5%) death-censored graft failures. Lower systolic and diastolic blood pressure were associated with better graft survival in the Kaplan-Meier analysis. Univariate analysis showed serum creatinine (HR 1.012, p < 0.001), duration of renal replacement therapy (HR 0.946, p = 0.012), age (HR 0.979, p = 0.014) and pulse pressure (HR 1.017, p = 0.044) to be predictors of graft survival with serum creatinine and duration of renal replacement therapy as the only significant factors in the multivariate analysis. Lower systolic and pulse pressure were associated with better patient survival in the Kaplan-Meier analysis. Age (HR) 1.062, p < 0.0001), serum creatinine (HR 1.002, p = 0.021), diabetes (HR 3.371, p < 0.0001), and pulse pressure (HR 1.013, p = 0.036) were significant predictors of patient survival in the univariate and multivariate analysis. Patient survival was reduced with increasing number of antihypertensives (p < 0.05), as was graft survival (p < 0.05). Reduced patient and graft survival were seen in patients prescribed calcium channel antagonists (p < 0.01). There was no increased patient mortality in those patients on beta-blockers or angiotensin converting enzyme (ACE) inhibitors. CONCLUSION: Hypertension is a risk factor, which remains despite the use of anti-hypertensives, for reduced patient and graft survival. The risk was not significant when blood pressure was entered together with serum creatinine in the multivariate analysis. Beta-blockers may have a beneficial effect on cardiovascular mortality, and ACE inhibitors a beneficial effect on both patient and graft survival. There is a pressing need for interventional studies to assess the impact of blood pressure targets on patient and graft survival and the effect of individual agents on these outcomes.

Adrenergic beta-Antagonists↗
PubMed2004

Cyclosporine in renal transplantation: a Scottish experience.

The renal transplant unit in Glasgow has performed over 1500 renal transplants since the introduction of cyclosporine (CyA) in 1984. We extracted data on all renal transplants from cadaveric donors, where the recipient received primary immunosuppression with CyA, between 1984 and 2002. A total of 1262 transplants were analyzed in four eras (1984-1988, 1989-1992, 1993-1996, 1997-2002). Over this time period we observed progressive improvement in graft and patient survival, with the clearest improvements coinciding with the introduction of the Neoral formulation of CyA.

Cadaver↗
PubMed2004

Random blood glucose measurements and survival in nondiabetic renal transplant recipients.

New-onset diabetes after renal transplantation (PTDM), a common consequence of immunosuppression, is associated with reduced patient survival. However, we know little about the impact of less marked changes in glucose homeostasis. To investigate this problem, we used data on average random blood glucose values during the first, second, and third months posttransplantation, derived from a cohort of 1186 patients who received their first cadaveric or living-donor transplant between 1984 and 2002. We analyzed both patient and death-censored graft survivals, subgrouping recipients into those with end-stage renal failure due to diabetic nephropathy versus those with PTDM versus patients without diabetes. We confirmed that PTDM patients display reduced survival following transplantation, but a long-term survival similar to that of patients with diabetic nephropathy and end-stage renal disease. However, among patients without diabetes, random blood glucose was also a strong determinant of outcome, even when in the low normal range. In contrast, neither the presence of diabetes nor random glucose levels showed a significant impact on graft survival. PTDM is recognized to be an important, potentially modifiable, risk factor for cardiovascular disease in transplant recipients. Our data suggest that there is a gradation of increased risk associated with impaired glycemic control that affects patients who do not have diabetes. These data support the need for improved understanding of glycemic control in transplant recipients and for more detailed screening for impaired glucose tolerance in this population.

Adult↗
PubMed2002

Diagnosis and treatment of atherosclerotic renal artery stenosis (ARAS).

Atherosclerotic renal artery stenosis (ARAS) is an increasingly common cause of secondary hypertension and progressive chronic renal failure. Recent studies provide valuable information about the pathophysiology, natural history, diagnosis and treatment of ARAS. The pathophysiology of ARAS is more complex than experimental models using clipped renal arteries because the renal artery narrowing is gradual, may be bilateral, may affect smaller intra-renal arteries and other co-existing nephropathies are often present. Patients with ARAS have high mortality due to associated co-morbidity and progression of renal failure may be less common than previously thought. Magnetic resonance arteriography offers great promise for diagnosing of ARAS as it is non-invasive and can provide data on kidney function. In patients with ARAS, the co-existence of atherosclerotic disease in other vascular beds means that aspirin, blood pressure reduction, advice to stop smoking and lipid lowering therapy are likely to be associated with reduced vascular events. The effect of these approaches on the progression of ARAS is unclear but likely to be beneficial. Re-vascularisation of occluded renal arteries is an attractive option for treatment of ARAS but data from the few randomised controlled studies that have been published do not support its widespread application. Arterial stenting has a higher technical success rate than angioplasty while surgical revascularisation does not appear to improve outcome compared with angioplasty. Recent studies examining functional and histological features of kidneys supplied by atherosclerotic stenosed renal arteries may explain why revascularisation is not always beneficial. The results of on-going studies may identify sub-groups of patients with ARAS who gain a clear benefit from re-vascularisation. In the meantime it seems reasonable to attempt re-vascularisation in the following circumstances: severe hypertension resistant to medical therapy, rapidly progressive renal failure with no obvious cause other than ARAS and recurrent flash pulmonary oedema.

Arteriosclerosis↗
PubMed2000

A new method of post-dialysis blood urea sampling: the 'stop dialysate flow' method.

BACKGROUND: A standardized practical method of post-dialysis blood sampling is required to improve the precision of using urea kinetics in the evaluation of haemodialysis dose and to permit comparative audit. The methods recommended in the Renal Association and Dialysis Outcomes Quality Initiative (DOQI) guidelines reduce the blood pump speed to a low rate at the end of haemodialysis before blood sampling after 10 and 15 s respectively. However, these 'low flow' methods compensate only partially for cardiopulmonary recirculation and may be impractical in routine practice because they involve sequential steps and require accurate timing of sampling. Therefore we have evaluated an alternative method of stopping only the dialysate flow at the end of the haemodialysis session before performing post-dialysis blood sampling. METHODS: The study was performed in three phases. Serial measurements of blood urea were obtained from arterial and venous samples taken at times 0, 30, 60, 120, 180, 240, 300 and 360 s after stopping dialysate flow and leaving the extracorporeal blood flow rate unchanged at the end of the haemodialysis session in 10 patients. A peripheral venous sample was also taken from the contralateral arm at 0 s to reflect body water urea concentration at the end of dialysis without the effect of access recirculation and with a minimal effect of cardiopulmonary recirculation. The same haemodialysis prescription was repeated in the same 10 patients using the Renal Association method to permit comparison between the two methods. The practical use of the 'stop dialysate flow' method was then evaluated in 117 regular haemodialysis patients undergoing routine monthly assessment of dialysis adequacy and compared with sampling immediately post-dialysis. RESULTS: Within 4 min of stopping the dialysate flow there was no difference between the blood urea concentrations of arterial and venous samples, indicating cessation of diffusion across the dialysis membrane. Also the blood urea concentrations in all of the arterial and venous samples between 4 and 6 min were constant and were equivalent to the blood urea concentration of the peripheral venous sample taken at 0 s. These data suggest that post-dialysis blood sampling may be performed 5 min after stopping dialysate flow at the end of the haemodialysis session. In contrast, the blood urea concentration in the post-dialysis samples obtained using the Renal Association method were lower than the contralateral arm blood urea concentration taken at 0 s (0.31+/-0.42; P<0.05) and consequently the percentage URR was higher (1.35+/-1.84%). In 117 patients the post-dialysis blood urea sample 5 min after stopping dialysate flow averaged 5.49+/-2.11 mmol/1 compared with 5.07+/-2.05 mmol/l immediately after the end of the haemodialysis session (P<0. 0001). This was equivalent to a reduction in URR from 71.7+/-8.3% with sampling immediately post-dialysis to 69.1+/-9.3% with the 'stop dialysate flow' method. CONCLUSIONS: This study shows that there is a window period between 4 and 6 min after stopping dialysate flow at the end of the haemodialysis session when the blood urea concentration in a sample taken from any part of the extracorporeal circuit remains constantly within the co-efficient of variation of laboratory measurement, and is equivalent to a peripheral venous sample taken immediately at the end of the dialysis session. A 'stop dialysate flow' method with blood sampling after 5 min offers several advantages over 'slow flow' methods, since it allows for cardiopulmonary as well as access recirculation, does not require precise timing of blood sampling, and is simple to perform in a busy renal unit. For these reasons the 'stop dialysate flow' method may be used for routine monitoring of the adequacy of delivered haemodialysis and for comparative audit among haemodialysis centres.

Adult↗
PubMed2000

The treatment of idiopathic membranous nephropathy.

Membranous nephropathy remains the most common cause of the nephrotic syndrome in adults. Most patients do well with long-term natural history studies reporting a 10-year renal survival of 70% to 90% but the remainder progress to end stage renal failure. This plus the associated morbidity of those with persistent high grade proteinuria makes the decision about the timing and type of treatment difficult. Models have been developed to help predict at an early stage of the disease those at the highest risk of progression and their use is encouraged. The use of nonspecific, nontoxic therapy, ie, angiotensin-converting enzyme inhibitor (ACEI), for both hypertension control and their renoprotective effect is supported by evidence from high-quality studies. Modest dietary protein restriction may be of use but its effect is more controversial. If subnephrotic proteinuria plus normal renal function is present or inducible, conservative therapy and ongoing observation is probably all that is warranted. If high-grade proteinuria (>3.5 g/d) persists then the Italian regime consisting of cytotoxic therapy alternating monthly with prednisone treatment for three cycles has shown the best evidence of long-term induction of remission of proteinuria and preservation of renal function. If this fails or is judged too toxic then a 6- to 12-month course of cyclosporine seems warranted, especially if renal function is deteriorating. Introduction of treatment for risk reduction of both secondary effects of the disease and for modification of the adverse effects of immunosuppressive drugs should be considered in cases with high-grade persistent proteinuria.

Adult↗
PubMed1999

Prevalence of angiographic atherosclerotic renal artery disease and its relationship to the anatomical extent of peripheral vascular atherosclerosis.

BACKGROUND: Recognition of the possible presence of atherosclerotic renal artery disease (ARAD) is important because of its progressive nature, and because of the potential for precipitating an acute deterioration in renal function by administration of angiotensin-converting enzyme inhibitors. The aim of this study was to identify the prevalence of ARAD in patients undergoing peripheral angiography and its relationship to the extent of their peripheral vascular disease (PVD). METHODS: The reports of the 218 patients who underwent peripheral angiography to investigate PVD in one centre in a calendar year, and in whom it was possible to image the renal arteries, were analysed retrospectively. The presence of atherosclerotic disease in the renal, aortic, iliac, femoral and distal areas was recorded for each patient. RESULTS: The prevalence of ARAD was 79/218 (36.2%). The greater the number of atherosclerotic areas of the arterial tree, the higher the prevalence of ARAD. Patients with aortic disease and bilateral iliac, femoral and distal vessel disease had the highest incidence of ARAD 19/38 (50%). The incidence of ARAD in those with femoral artery atherosclerosis was significantly higher than in those without femoral artery atherosclerosis (42.1% compared with 9.7%, P=0.001 chi2). There was no significant difference in those groups with or without iliac and distal disease. None of the 11 patients with normal femoral and iliac arteries had ARAD. CONCLUSIONS: Renal artery atherosclerosis is a common occurrence in patients with PVD. If extensive PVD is recognized during aortography, a high flush should be considered to examine the renal arteries, if they are not included in the main study.

Adult↗
PubMed1998

An artificial neural network can select patients at high risk of developing progressive IgA nephropathy more accurately than experienced nephrologists.

BACKGROUND: The object of the study was to develop an artificial neural network (ANN) to identify patients with IgA nephropathy (IgAN) with a poor prognosis and to compare the predictions of the ANN with the predictions of six experienced nephrologists. METHODS: The following data from the time of renal biopsy were retrieved from the records of 54 patients with IgAN: age, sex, systolic and diastolic blood pressure, number of prescribed antihypertensive drugs, 24-h urine protein excretion, and serum creatinine. Patients aged less than 14 years, or who had serum creatinine > 350 mumol/l at presentation, liver disease or concomitant kidney disease were excluded. Outcome was assigned as 'stable' if serum creatinine was < 150 mumol/l after 7 years and 'non-stable' if serum creatinine was > or = 150 mumol/l. The ANN was trained and tested using a 'jack-knife' sampling technique and performance evaluated in terms of number of correct predictions, sensitivity and specificity. The six nephrologists were asked to predict outcome at 7 years for each patient using the same data as the ANN and their performance was assessed in the same manner. RESULTS: The ANN assigned the correct outcome to 47/54 (87.0%) patients: sensitivity 19/22 (86.4%), specificity 28/32 (87.5%). The mean score for nephrologists was 37.5/54 (69.4%, range 35-40), mean sensitivity 72% and mean specificity 66%. CONCLUSIONS: An ANN trained using routine clinical information obtained at the time of diagnosis can potentially predict 7-year outcome for renal function in IgAN more accurately than experienced nephrologists, and can therefore identify a group of high-risk patients requiring close follow-up.

Adolescent↗
PubMed1998

Factors influencing long-term primary cadaveric kidney transplantation--importance of functional renal mass versus avoidance of acute rejections--the Toronto Hospital experience 1985-1997.

1. The 5-year actuarial graft, patient and functional graft survival rates were analyzed in 743 consecutive primary cadaveric kidney transplants from The Toronto Hospital between January 1985-December 1997. 2. Recipient age > or = 55 years, male recipient sex, recipient diabetes mellitus, CIT > 36 hours and delayed graft function were found to significantly decrease patient survival. 3. Recipient age > or = 55 years, sensitization to HLA antigens (peak PRA > 50%), donor/recipient HLA antigen mismatches, CIT > 36 hours, delayed graft, function and 6-month SCr > 200 mumol/L were found to significantly decrease graft survival. 4. Acute rejection episodes had no significant impact on overall 5-year patient or graft survival. 5. The observation that serum creatinine > 200 mumol/L had a major adverse influence on long-term outcome reflects the importance of functional renal mass on graft survival.

Adult↗
PubMed1998

Insertion of internal jugular temporary hemodialysis cannulae by direct ultrasound guidance--a prospective comparison of experienced and inexperienced operators.

OBJECTIVE: Previous studies have shown that inexperienced operators have a lower success rate than experienced operators for insertion of internal jugular cannulae using the anatomical landmark technique. The object of this study was to determine the rate of successful insertion, incidence of immediate complications and incidence of infection for temporary hemodialysis cannulae inserted under ultrasound guidance by experienced and inexperienced operators. METHODS: The reason for insertion, patient age, reason for failed insertion, immediate complications, duration of cannula survival and reason for removal were recorded prospectively for 107 attempted cannulations by 7 operators in 72 subjects with renal failure. Operators were defined as "experienced" (more than 3 years postgraduate clinical experience and more than 25 previous central vein cannulae inserted) or "inexperienced" (less than 3 years postgraduate clinical experience and less than 3 previous central vein cannulae inserted). Rates of successful cannulation and incidence of complications were compared for experienced and inexperienced operators. Cannula survival without infection was analysed by Kaplan-Meier survival for experienced and inexperienced operators. RESULTS: The overall success rate of cannula insertion at first site was 103/107 (96.3%) with no difference between experienced and inexperienced operators (56/58 vs. 47/49). 103 internal jugular temporary haemodialysis cannulae were inserted into 72 subjects. The only immediate complication was incorrect positioning of the cannula in 6 cases requiring manipulation. The median survival of hemodialysis cannulae was 14 days (range 1-111). 64.1% cannulae functioned for as long as required. Of the remainder, 33/36 were removed because of presumed cannula related infection. There was no difference in the median duration of cannula survival between experienced and inexperienced operators (15 days versus 12 days; Mann-Whitney point estimate = -1.00; 95% confidence interval -6.00, 3.00). p = 0.66) or in the probability of cannula survival without infection by Kaplan Meier analysis. CONCLUSION: We conclude that ultrasound guided temporary haemodialysis cannulation is a safe procedure with a high rate of success, the success rate for inexperienced operators is much higher than previous studies of cannulation using the anatomical landmark technique and the rate of cannula removal due to infection is not influenced by operator experience.

Catheterization, Central Venous↗
PubMed1997

The influence of familial factors on the progression of IgA nephropathy.

BACKGROUND: Vascular risk factors in first degree relatives of patients with insulin dependent diabetes mellitus are known to increase the risk of that patient developing diabetic nephropathy. We explored the influence of vascular risk factors in first degree relatives on patients with stable (serum creatinine < 150 mumol/l for > 5 years) and progressive (serum creatinine > 200 mumol/l, and > 150% serum creatinine at presentation, after minimum follow-up at 2 years) IgA nephropathy (IgAN). METHODS: We compared sodium-lithium countertransport activity (SLC Vmax), plasma lipoprotein(a) and von Willebrand factor (vWf) concentrations, incidence of vascular disease, and incidence of hypertension in 37 first degree relatives of 23 patients with stable IgAN and 33 first degree relatives of 17 patients with progressive IgAN. The two groups of relatives were comparable with respect to other risk factors: age, smoking, blood pressure, and plasma glucose, creatinine, cholesterol and triglyceride concentrations. RESULTS: SLC Vmax was higher in relatives of stable patients (mean 0.37 mmol/h/l RBC [S.D. 0.18] vs 0.30 [S.D. 0.09]; P = 0.034 two-sample t-test). There was no difference between the relatives of stable and progressive patients in plasma lipoprotein(a) concentration (median 11.5 mg/l vs 13.0: P = 0.45; 95% C.I. -12 to 3; Mann-Whitney test), plasma vWf concentration (149.4 IU/dl [S.D. 55.6] vs. 163.2 IU/dl [S.D. 57.3]; P = 0.31 two-sample t-test), or incidence of hypertension (13/37 [35.1%] vs 10/33 [30.3%]; chi 2 = 0.185; P = 0.667). Relatives of patients with progressive IgAN had a slightly higher incidence of vascular disease (10/33 [30.3%] vs 8/37 [21.6%]; chi 2 = 0.688; P = 0.407). CONCLUSIONS: Familial vascular risk may increase the likelihood of progressive renal failure in patients with IgAN but the influence is likely to be small and unrelated to the factors we measured. SLC Vmax was significantly higher in relatives of patients with stable disease which contrasts with data from other studies and is unexplained.

Adult↗