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Biomedical subjects

K Farrington

Publications and source records attributed to K Farrington.

At least 19 recordsLinked to original sources
PubMed2006

Management of acute renal failure.

Acute renal failure is a common condition, frequently encountered in both community practice and hospital inpatients. While it remains a heterologous condition, following basic principles makes investigation straightforward, and initial management follows a standard pathway in most patients. This article shows this, advises on therapeutic strategies, including those in special situations, and should help the clinician in deciding when to refer to a nephrologist, and when to consider renal replacement therapy.

Acidosis↗
PubMed2004

Polymyalgia rheumatica preceding small-vessel vasculitis: changed spots or misdiagnosis?

BACKGROUND: Systemic small-vessel vasculitis (SVV) is increasing in incidence and age of diagnosis. Presenting features may mimic those of polymyalgia rheumatica (PMR), a common disease of the elderly. AIM: To test the hypotheses that SVV is frequently misdiagnosed as PMR in elderly patients, that this results in a delay in diagnosis and appropriate treatment, and that the natural history and clinical features are different. DESIGN: Retrospective case-control study. METHODS: Cases of glomerulonephritis due to SVV at a single centre over a 12-year period were analysed, comparing those treated previously for PMR (PMR(+)) to the remainder of the cohort (PMR(-)). RESULTS: Of 86 patients with complete follow-up, 13% had been treated previously for PMR. PMR(+) patients had a longer duration of symptoms prior to SVV diagnosis (396 vs. 107 days, p = 0.001) and were less likely to be dialysis-dependent at diagnosis (36% vs. 68%, p < 0.05). Despite the delay in diagnosis, there was a trend towards lower serum creatinine (392 vs. 591 micro M), lower relapse rate (0.04 versus 0.15 episodes/patient-year) and lower incidence of death/end-stage renal failure (27% vs. 53%) in the PMR(+) group. DISCUSSION: SVV is frequently misdiagnosed as PMR, especially in those patients with indolent disease, although this did not appear to adversely affect outcome. We recommend that all patients suspected of suffering from PMR undergo careful urinalysis to look for haematuria or proteinuria, and that a low threshold for ANCA testing is maintained.

Aged↗
PubMed2001

Wegener's granulomatosis presenting as acute suppurative interstitial nephritis.

A 78 year old man presented with acute renal failure following a prolonged respiratory illness. A renal biopsy demonstrated severe suppurative interstitial nephritis with normal glomeruli. After nine weeks of antibiotics he remained anuric and a second biopsy demonstrated pauci-immune, necrotising glomerulonephritis. His subsequent clinical course was consistent with a diagnosis of Wegener's granulomatosis and antineutrophil cytoplasmic antibodies (ANCA) were detected. This is the first reported case of Wegener's granulomatosis presenting with an isolated tubulointerstitial lesion.

Acute Disease↗
PubMed1999

Is there a rationale for rationing chronic dialysis? A hospital based cohort study of factors affecting survival and morbidity.

OBJECTIVES: To determine factors influencing survival and need for hospitalisation in patients needing dialysis, and to define the potential basis for rationing access to renal replacement therapy. DESIGN: Hospital based cohort study of all patients starting dialysis over a 4 year recruitment period (follow up 15-63 months). Groups were defined on the basis of age, comorbidity, functional status, and whether dialysis initiation was planned or unplanned. SETTING: Renal unit in a district general hospital, which acts as the main renal referral centre for four other such hospitals and serves a population of about 1.15 million people. SUBJECTS: 292 patients, mean age 61.3 years (18-92 years, SD 15.8), of whom 193 (66%) were male, and 59 (20%) were patients with diabetes. Dialysis initiation was planned in 163 (56%) patients and unplanned in 129 (44%). MAIN OUTCOME MEASURES: Overall survival, 1 year survival, and hospitalisation rate. RESULTS: Factors affecting survival in the Cox's proportional hazard model were Karnofsky performance score at presentation (hazard ratio 0.979, 95% confidence interval 0.972 to 0. 986), comorbidity severity score (1.240, 1.131 to 1.340), age (1.036, 1.018 to 1.054), and myeloma (2.15, 1.140 to 4.042). The Karnofsky performance score used 3 months before presentation was significant (0.970, 0.956 to 0.981), as was unplanned presentation in this model (1.796, 1.233 to 2.617). Using these factors, a high risk group of 26 patients was defined, with 19.2% 1 year survival. Denying dialysis to this group would save 3.2% of the total cost of the chronic programme but would sacrifice five long term survivors. Less rigorous definition of the high risk group would save more money but lose more long term survivors. CONCLUSIONS: Severity of comorbid conditions and functional capacity are more important than age in predicting survival and morbidity of patients on dialysis. Late referral for dialysis affects survival adversely. Denial of dialysis to patients in an extremely high risk group, defined by a new stratification based on logistic regression, would be of debatable benefit.

Activities of Daily Living↗
PubMed1999

Outcome of primary radiocephalic fistula for haemodialysis.

BACKGROUND: Patient characteristics may help select the most appropriate type of permanent vascular access for haemodialysis. The aim of this study was to assess the influence of patient-related variables on the outcome of radiocephalic fistulas. METHODS: Over 3 years 107 consecutive patients underwent formation of a radiocephalic fistula for permanent haemodialysis access. Patients receiving prosthetic, ulnar, brachial or secondary fistulas were excluded. Patients were followed prospectively until access failure, transplantation or death, or for a minimum of 6 months (median follow-up 24 months). RESULTS: Primary patency was 69 per cent at 12 months and 56 per cent at 24 months. Endovascular and surgical intervention led to limited improvement in secondary patency to 63 per cent at 24 months. Regression analysis showed that fistula failure was more common in women (P = 0.02), diabetics (P = 0.03) and young patients (P = 0.02). By life-table analysis, primary and secondary patency were significantly better (P = 0.01) for men and non-diabetics, while the outcome was similar for all age groups. CONCLUSION: One-third of radiocephalic fistulas fail irreversibly within 2 years. Failure is more likely in women and diabetic patients.

Aged↗
PubMed1999

What is hypertension in chronic haemodialysis? The role of interdialytic blood pressure monitoring.

BACKGROUND: Hypertension in chronic haemodialysis patients contributes significantly to morbidity and mortality. Treatment decisions are usually based on predialysis readings, which may not accurately reflect control during the interdialytic period. METHODS: We studied 40 randomly selected subjects on haemodialysis and compared readings by different methods at set times during the dialysis session with the 48-h interdialytic ambulatory readings. Conventional sphygmomanometer, automated Dinamap and Tm 2421(A&D) ambulatory monitor were used for BP measurements. RESULTS: Conventional sphygmomanometry and self measured automatic readings (Dinamap) were highly correlated (systolic r=0.93, P<0.001; diastolic r=0.90, P<0.001). Mean blood pressure on arrival ((PreC(0)) 158 mmHg systolic, 80 mmHg diastolic and 106 mmHg mean) significantly overestimated the mean ambulatory reading during the 6 h prior to attendance ((preAm(6h)) systolic 147 (P<0.01), diastolic 75 (P<0.01), mean 99 (P<0.01)). Fifteen patients (41%) demonstrated a marked difference (>20/10 mmHg) between the PreC(0) and preAm(6h) (white-coat effect) persisting in seven patients (19%) after a period of rest 10 min predialysis (preC(10)) and present even in self-recorded Dinamap readings. There was a significant negative relationship between the systolic rise and the number of months on dialysis (P<0.05). Mean ambulatory BP on interdialytic day 2 was significantly greater than on day 1 whereas the awake-sleep differences were less on day 2 than day 1, both perhaps reflecting differences in volume status. The 20 min post-dialysis measurement (PoC(20)) for systolic, diastolic, and mean, unlike predialysis (PreC(0) and preC(10)), onset (onC) and end of dialysis readings (enC) did not differ significantly from 48 h interdialytic means. CONCLUSIONS: The best representation of interdialytic pressure was the 20-min post-dialysis reading. Walk-in predialysis pressures overestimate mean interdialytic pressures due to a high incidence of white-coat effect, which shows some habituation with time on dialysis. Ambulatory monitoring has a role in evaluating persistent poor blood pressure control in haemodialysis patients.

Adult↗
PubMed1999

The effect of exercise during haemodialysis on solute removal.

BACKGROUND: Urea rebound results as urea re-equilibrates between intracellular and intravascular compartments post haemodialysis. The mechanism of the rebound is thought to be due to either a reduced diffusion rate or blood flow. It is hypothesized that low blood flow in the skeletal muscles might be responsible. We tested this by studying the effect of exercise during dialysis on the removal of urea, creatinine and potassium. METHODS: Eleven patients (aged 32-78 years) on haemodialysis (4-58 months) were studied on paired dialysis sessions; one with exercise and the other as a control. Patients pedalled on a cycle for 5-20 min at submaximal workload followed by 10 min rest to achieve a total of 60 min exercise. Plasma concentrations of urea, creatinine and potassium were measured pre-, post- and 30-min post dialysis. The post-dialysis rebound (% rebound) and reduction ratios (RR) of the solutes and equilibrated (two-pool) urea Kt/V were calculated for comparison. RESULTS: The rebound of all three solutes was reduced significantly following exercise. The rebound of urea decreased from 12.4 to 10.9% (median, P<0.01 Wilcoxon signed rank test), creatinine from 21.2 to 17.2% (P<0.001) and potassium from 62 to 44% (P<0.05). Kt/V and RR increased significantly as a result: Kt/V urea from 1.00 to 1.15 (P=0.001), RR urea from 0.63 to 0.68 (P<0.001); Kt/V creatinine from 0.71 to 0.84 (P<0.01); and RR creatinine from 0.51 to 0.57 (P<0.05). CONCLUSION: Exercise increased the efficiency of dialysis by reducing the rebound of solutes due to increased perfusion of the skeletal muscles.

Adult↗
PubMed1999

Clinical, radiological and serum amyloid P component scintigraphic features of beta2-microglobulin amyloidosis associated with continuous ambulatory peritoneal dialysis.

BACKGROUND: Beta2-Microglobulin (beta2M) amyloidosis occurs in patients with end-stage renal failure (ESRF) who undergo long-term continuous ambulatory peritoneal dialysis (CAPD), but its prevalence in patients treated exclusively by CAPD is unknown. In addition, its features may differ from those of haemodialysis-associated beta2M amyloidosis because CAPD is more biocompatible. METHODS: We performed serum amyloid P component (SAP) scintigraphy, a specific technique for imaging amyloid deposits, in 13 consecutive patients with ESRF who had been dialysed for >5 years, at least 80% of the time by CAPD. Clinical and radiological features of beta2M amyloidosis were sought and compared with the results of SAP scintigraphy. RESULTS: SAP scans showed articular amyloid deposits in seven patients, all of whom had evidence of carpal tunnel syndrome and four of whom had arthralgia characteristic of dialysis amyloidosis. Typical radiographic bone cysts were present in only one case who had been dialysed for >17 years. The remaining six patients had no clinical, radiological or scintigraphic evidence of beta2M amyloidosis. CONCLUSIONS: The prevalence of beta2M amyloidosis in this study was comparable with that in reported haemodialysis populations. Many of the amyloid deposits demonstrated by SAP scintigraphy were not associated with symptoms, but larger and longer term studies are required to determine whether CAPD favourably influences their clinical expression.

Adult↗
PubMed1997

Low serum vitamin B12 levels in chronic high-flux haemodialysis patients.

The occurrence of vitamin B12 (B12) deficiency in chronic haemodialysis patients and the need for its supplementation in these patients are still matters of debate. We measured serial predialysis serum B12 levels, at 3- to 6-month intervals, in 67 unselected patients on our high-flux haemodialysis programme. Over a 12-month period, there was a significant fall in serum B12 from 497 +/- 200 (SD) to 391 +/- 131 ng/l (p < 0.001). 22 patients developed subnormal serum B12 levels and were commenced on hydroxocobalamin supplements. We were unable to demonstrate B12 clearance during dialysis using blood side studies. Measurement of B12 in the dialysate showed that 0-4.5 microg B12 was cleared per dialysis. Using these B12 measurements, in vivo B12 clearance was estimated at 9.1 ml/min. Dietary studies on 24 unselected patients showed borderline or low B12 intake in 4 patients. Absorption studies by whole-body counting on 6 patients using 57Co and 58Co showed normal B12 absorption. The same radioisotope studies demonstrated no B12 adsorption to the dialyser membrane. This study demonstrates that low serum B12 levels occur in high-flux haemodialysis patients and that losses during dialysis and dietary deficiency may be contributing factors.

Adsorption↗
PubMed1996

The post-hemodialysis rebound: predicting and quantifying its effect on Kt/V.

Immediately after hemodialysis, the urea concentration rebounds upwards as urea continues to be transferred into the arterial circulation from peripheral body compartments. This rebound takes at least 30 minutes to complete. Hemodialysis is quantified as the Kt/V, calculated prom pre- and post-dialysis urea samples. Unless the post-dialysis sample is taken at least 30 minutes after dialysis, the Kt/V will be overestimated. This overestimation will be relatively greater in short high-efficiency dialyses, which have greater post-dialysis rebounds. We propose a method of correction that uses only the conventional pre- and immediate post-dialysis samples and is based on the physiologically-appropriate patient clearance time (tp). This is the time needed to clear all body compartments when the dialyzer clearance is infinite. The tp can be calculated from the pre-, immediate post- and 30-minute post-dialysis urea concentrations and was 35 minutes (SD 16) in 29 patients undergoing short (149 min) hemodiafiltration and standard (243 min) hemodialysis the following week. There was no significant difference between tp values calculated during the two treatments. Standard Kt/V can be corrected by multiplying by t/(t + tp) and dialysis time should be increased by tp x Kt/V minutes to compensate for the rebound. Despite individual variations in tp, a value of tp = 35 was sufficient to correct Kt/V in all patients. Kt/V corrected in this way agreed with Kt/V calculated using a 60-minute post-dialysis sample (r = 0.856, P < 0.001). The method predicted the 60-minute post-rebound concentration (SE 0.5 mM, r = 0.983, P < 0.001) and the addition of 35 minutes to the treatment time corrected for the rebound in both conventional and short treatments. Similar simple equations corrected the error in V caused by rebound effects.

Adult↗