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Biomedical subjects

L R Baker

Publications and source records attributed to L R Baker.

At least 19 recordsLinked to original sources
PubMed1999

Temporary vascular access for first dialysis is common, undesirable and usually avoidable.

BACKGROUND: When technically feasible, patients with end-stage renal failure should commence regular dialysis treatment with permanent access to the circulation (by arteriovenous fistula) or peritoneum (by soft peritoneal catheter) in situ, thus avoiding the need for initial hemodialysis employing temporary vascular access. We have examined the frequency, consequences and avoidability of temporary access in such patients. METHODS: 178 patients commencing regular dialysis between August 1993 and April 1995 were analysed retrospectively using case notes. Patients were divided into those who had permanent dialysis access in situ when they commenced dialysis and those who required temporary access. If temporary access was required, the patients were further analysed into those who had been first seen by a nephrologist at least 12 weeks before the first dialysis, and those who had been referred "late". It was assumed that 12 weeks was sufficient time for permanent access to be instituted. Mortality within the first 90 days of commencing dialysis was recorded. RESULTS: Seventy-four of 82 patients opting for regular hemodialysis and 53 of 96 opting for peritoneal dialysis required temporary vascular access. Late referral accounted for 47 and delays within the renal service for 35 of such patients. Late presentation to the medical profession or indecisiveness on the part of the patient accounted for the remainder. Twenty-five of 127 patients requiring temporary access but only one or 51 patients not requiring it died within 90 days of commencement of treatment. CONCLUSION: Late presentation to a renal unit prior to first dialysis is associated with increased mortality. Late referral or late presentation are associated with an increased need for temporary vascular access for first dialysis. Many patients who require temporary access for first dialysis could have been better managed.

Adult↗
PubMed1999

Reduction of left ventricular mass index with blood pressure reduction in chronic renal failure.

AIM: We have reported previously in a study of 85 non-diabetic patients with chronic renal failure (CRF) that 24-h ambulatory blood pressure (ABP) recording and echocardiography are required for accurate diagnosis of inadequate blood pressure (BP) control and early left ventricular hypertrophy (LVH). In this study we found that the only independent determinants of left ventricular (LV) mass were hypertension, male sex, body mass index (BMI) and anemia. Little is known about the progression of LVH in patients as they progress from moderate to end-stage renal failure. PATIENTS AND METHODS: We undertook a follow-up observational study in a cohort of 65 (26 male, 12 black Afro-Caribbean and 7 Asian) of those patients originally investigated. Patients who had reached end-stage renal failure (ESRF) were not studied. RESULTS: A statistically significant correlation was found between change in left ventricular mass index (LVMI) and change in mean ABP parameters (r = 0.27 (p<0.03) for 24-h systolic, r = 0.21 (p<0.05) for 24-h diastolic, r = 0.29 (p<0.02) for mean arterial pressure (MAP), r = 0.24 (p<0.05) for daytime systolic, r = 0.30 (p<0.02) for nocturnal systolic and r = 0.26 (p<0.05) for nocturnal diastolic BP). Hemoglobin concentration and BMI changed little between the two studies and no other statistically significant correlations were found in respect of any other parameters studied, which has allowed us to isolate the effect of one determinant - adequacy of BP control-upon LVH. CONCLUSION: In patients with moderate chronic renal impairment, reduction in BP is associated with reduction of LVMI over time. Among the antihypertensive agents ACE inhibitors appeared to have the greatest ability to reduce LV mass in the subjects with LVH at baseline. Larger interventional studies are needed to determine whether ACE inhibitors are superior to other anti-hypertensive agents in LVH regression in chronic renal failure patients.

Adult↗
PubMed1998

Seminal megavesicles with adult polycystic kidney disease.

Adult polycystic kidney disease has been found in association with pathological dilatation of the seminal vesicles in six patients. These men appeared normal on clinical examination, but had azoospermia or severe oligozoospermia. They were investigated by scrotal exploration with vasography, renal and transrectal ultrasound scans (TRUS), and percutaneous puncture of the seminal vesicles in one case, before and after resection of the ejaculatory ducts. This revealed that the gross dilatation of the seminal vesicles was not caused by obstruction, but appeared to be due to atonicity (megavesicles). These ultrasonic appearances, when described previously, were incorrectly thought to be due to seminal vesicle cysts.

Adult↗
PubMed1997

Technetium-99m methoxy isobutyl isonitrile (MIBI) imaging of the parathyroid glands in patients with renal failure.

BACKGROUND: Technetium-99m methoxy isobutyl isonitrile (Tc-99m MIBI) scintigraphy has been reported to be at least as reliable as thallium-technetium subtraction imaging in the preoperative localization of hyperplastic parathyroid glands in patients with renal failure. Reports have suggested that 50% of glands can be identified correctly by this method. The aim of this study was to improve on previous results and demonstrate that Tc-99m MIBI imaging has an important place in the preoperative work-up of these patients. METHODS: Eighteen patients on renal replacement therapy were studied. All had tertiary hyperparathyroidism and had Tc-99m MIBI imaging prior to parathyroidectomy. A refined reporting method was employed. The imaging results were compared to the subsequent surgical and histological findings. RESULTS: In the 12 patients in whom serum parathyroid hormone levels fell postoperatively to within or below the normal range, 38 of 46 glands (82.6%) were correctly identified and located in the correct quadrant of the thyroid gland. There were two false positive results where the imaging predicted glands not subsequently found by the surgeon. In the patients who had post-operative hyperparathyroidism, repeat Tc-99m MIBI imaging was able to locate accurately the site of the residual parathyroid tissue. CONCLUSIONS: Tc-99m MIBI imaging is able to identify more than 80% of hyperplastic parathyroid glands in renal failure patients if this reporting process is used, and locate them in the correct quadrant of the thyroid gland. Tc-99m MIBI imaging is of particular value when re-exploration of the neck is required for post-parathyroidectomy hyperparathyroidism. These results represent a significant improvement on the sensitivity of this imaging technique when compared to previous published data.

Adult↗
PubMed1997

Left ventricular hypertrophy and ambulatory blood pressure monitoring in chronic renal failure.

BACKGROUND: Left ventricular hypertrophy (LVH) is both common and an important predictor of risk of death in end-stage renal failure (ESRF). In mild to moderate chronic renal failure (CRF), the timing of onset of LVH and the factors involved in its initial development have not been fully elucidated. The present study was undertaken to examine the prevalence and potential determinants of echocardiographically determined LVH in this connection, and to compare 24-h ambulatory blood pressure (BP) recordings with BP measured at a previous clinic visit. METHODS: From a cohort of 120 non-diabetic patients who had been attending a nephrology clinic, 118 agreed to participate in the study. Of these we selected for analysis 85 stable patients (37 male). Patients with known cardiovascular disease, those with a history of poor compliance with antihypertensive medication, and those in whom such medication had been changed in the previous 3 months were excluded. Clinic BP, 24-h ambulatory BP, echocardiography, body mass index (BMI), serum creatinine (SCr), creatinine clearance (CrCl), haemoglobin (Hb), fasting cholesterol (CHOL), triglyceride TRIGL), plasma glucose, calcium (Ca), phosphate (PO4), alkaline phosphatase (ALK PHOS), parathyroid hormone (PTH) concentrations, and 24-h urinary protein were assessed in all patients. Seventy-seven per cent were on antihypertensive medication. RESULTS: LVH was detected in 16% of patients with CrCL > 30 ml/min, and 38% of patients with CrCl < 30 ml/min. By stepwise regression analysis, ambulatory systolic BP (P < 0.0001), male gender (P < 0.0001), BMI (P < 0.0002), and Hb concentration (P < 0.002) were the only independent determinants of left ventricular (LV) mass. Nocturnal systolic BP (P < 0.02) was the main determinant of LVH in the group of patients with advanced CRF. The correlation between left ventricular mass index (LVMI) and mean 24-h ambulatory systolic BP (r = 0.52, 95% confidence interval 0.50-0.54) was statistically significantly stronger than with outpatient systolic BP (r = 0.25, 95% confidence interval 0.23-0.27). The same was true for the correlation between LVMI and mean 24-h ambulatory diastolic BP (r = 0.42, 95% confidence interval 0.40-0.44), and outpatient diastolic BP (r = 0.22, 95% confidence interval 0.20-0.24). CONCLUSIONS: Twenty-four hour ambulatory BP recording and echocardiography are required for accurate diagnosis of inadequate BP control and early LVH in patients with chronic renal impairment, independent determinants of which are hypertension, male sex, BMI, and anaemia.

Adult↗
PubMed1997

Serum C-reactive protein as a marker for infection and inflammation in regular dialysis patients.

Serum C-reactive protein (CRP) concentration was measured in 98 hemodialysis (HD) patients and 68 continuous ambulatory peritoneal dialysis patients (CAPD). The effect, if any, of a HD session on serum CRP level and the usefulness of CRP in diagnosing and monitoring proven inflammatory disease were studied. Seventy-five percent of CAPD patients without evidence of inflammation had CRP levels within the quoted normal range (< 10 mg/l), as compared with only 47% of HD patients also without evidence of overt inflammation (p < 0.001). No significant change in the CRP level was detected during a hemodialysis session. Twenty-four patients with overt inflammation (due mainly to infection) were studied, 22 of whom had CRP levels of > 50 mg/l. These increased CRP levels fell with treatment. A CRP level of > 50 mg/l proved highly suggestive of a significant inflammatory process and a value of < 10 mg/l always excluded it. The total period of time on the regular dialysis program was not related to the CRP level. A subclinical inflammatory response resulting in a raised CRP is very common in our hemodialysis patients and less so in CAPD patients. Possible reasons for this are discussed. However, CRP is still useful in the diagnosis and monitoring of response to treatment of inflammatory disease if the level is > 50 mg/l or serial/baseline measurements are available for comparison. Whether any relationship exists between elevation of CRP and the well-documented increased risk of cardiovascular death in dialysis patients is currently unknown.

Adolescent↗
PubMed1996

A randomized controlled study of iron supplementation in patients treated with erythropoietin.

In view of current uncertainty regarding the optimum route for iron supplementation in patients receiving recombinant human erythropoietin (EPO), a prospective randomized controlled study was designed to investigate this issue. All iron-replete renal failure patients commencing EPO who had a hemoglobin concentration < 8.5 g/dl and an initial serum ferritin level of 100 to 800 micrograms/liter were randomized into three groups with different iron supplementation: Group 1, i.v. iron dextran 5 ml every 2 weeks; Group 2, oral ferrous sulphate 200 mg tds; Group 3, no iron. All patients were treated with 25 U/kg of EPO thrice weekly subcutaneously. The hemoglobin concentration, reticulocyte count, serum ferritin, transferrin saturation, and EPO dose were monitored every two weeks for the first four months. Thirty-seven patients entered the study (12 i.v., 13 oral, 12 no iron). The three groups were equivalent with regard to age, sex, and other demographic details. Even allowing for dosage adjustments, the hemoglobin response in the group receiving i.v. iron (7.3 +/- 0.8 to 11.9 +/- 1.2 g/dl) was significantly greater than that for the other two groups (7.2 +/- 1.1 to 10.2 +/- 1.4 g/dl and 7.3 +/- 0.8 to 9.9 +/- 1.6 g/dl for Groups 2 and 3, respectively; P < 0.005 for both groups vs. Group 1 at 16 weeks). There was no difference between the groups supplemented with oral iron and no iron. Serum ferritin levels remained constant in those receiving i.v. iron (345 +/- 273 to 359 +/- 140 micrograms/liter), in contrast to the other two groups in which ferritin levels fell significantly (309 +/- 218 to 116 +/- 87 micrograms/liter and 458 +/- 206 to 131 +/- 121 micrograms/liter for Groups 2 and 3, respectively; P < 0.0005 for Group 1 vs. Group 2, and P < 0.005 for Group 1 vs. Group 3 at 16 weeks). Dosage requirements of EPO were less in Group 1 (1202 +/- 229 U/kg/16 weeks) than in Group 2 (1294 +/- 314 U/kg/16 weeks) or Group 3 (1475 +/- 311 U/kg/16 weeks; P < 0.05 vs. Group 1). The results of this study suggest that, even in iron-replete patients, those supplemented with i.v. iron have an enhanced hemoglobin response to EPO with better maintenance of iron stores and lower dosage requirements of EPO, compared with those patients receiving oral iron and no iron supplementation.

Cost-Benefit Analysis↗
PubMed1995

Antineutrophil cytoplasmic antibody-positive crescentic glomerulonephritis associated with anti-thyroid drug treatment.

Two cases of antineutrophil cytoplasmic antibody (ANCA)-positive vasculitis following treatment with propylthiouracil and carbimazole are described. Both patients had crescentic glomerulonephritis proven by renal biopsy and responded to immunosuppressive therapy and withdrawal of the anti-thyroid drugs. Though systemic vasculitis associated with propylthiouracil is reported, this is the first report to our knowledge of renal biopsy-proven vasculitis associated with either of these drugs.

Adult↗
PubMed1995

Prostate-specific antigen levels in patients receiving long-term dialysis.

OBJECTIVE: To investigate the effect, if any, of renal failure upon prostate-specific antigen (PSA) levels and the validity of PSA estimation as a marker of prostatic disease in renal failure. PATIENTS AND METHODS: PSA was measured in 65 men (median age 67 years, range 39-84) on regular haemodialysis and 37 men (median age 70 years, range 42-77) on continuous ambulatory peritoneal dialysis (CAPD). Patients with a PSA level > 4 ng/mL underwent prostatic biopsy guided by transrectal ultrasonography. RESULTS: There was no evidence of an artefactual elevation of PSA attributable solely to renal failure. All eight patients with a PSA level > 4 ng/mL had prostatic disease. CONCLUSION: PSA measurements in patients with end-stage renal failure treated by dialysis remain a useful marker of prostatic disease.

Adult↗
PubMed1995

Identification of auto-transplanted parathyroid tissue by Tc-99m methoxy isobutyl isonitrile scintigraphy.

Parathyroid tissue is sometimes auto-transplanted into the forearm after 'total' parathyroidectomy in patients with renal failure. Recurrent hyperparathyroidism demands identification of the source of PTH secretion which cannot be assumed to be the forearm. To this end, Tc-99m methoxy isobutyl isonitrile (MIBI) scintigraphy was used to identify functioning auto-transplanted parathyroid tissue in seven patients undergoing renal replacement therapy (five with functioning renal transplants and two on haemodialysis). Serum PTH was estimated in venous blood taken proximal and distal to the forearm graft and from the contralateral arm, and subsequent Tc-99m MIBI scanning was carried out without knowledge of the PTH results. Five patients had a significant gradient in PTH levels between sites proximal and distal to the graft, and between the proximal site and the contralateral arm, suggesting functioning parathyroid tissue in the graft. Subsequent Tc-99m MIBI scintigraphy confirmed the activity of the auto-transplanted parathyroid tissue in these five patients. In the remaining two patients without a significant PTH gradient between the sampling sites, Tc-99m MIBI scintigraphy did not identify any functioning forearm parathyroid tissue. The scan results therefore correlated well with the gradients in PTH levels, suggesting that MIBI scintigraphy can be used to identify functioning auto-transplanted parathyroid tissue. The results also indicate that any patient who has undergone auto-transplantation of parathyroid tissue must have blood samples taken from veins proximal to the graft and either distal to it, or from the contralateral arm when parathyroid status is re-assessed, particularly when surgery is being considered for recurrent hyperparathyroidism.

Adult↗