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Biomedical subjects

F D Thompson

Publications and source records attributed to F D Thompson.

At least 19 recordsLinked to original sources
PubMed2001

Outcome in patients with end-stage renal disease following heart or heart--lung transplantation receiving peritoneal dialysis.

BACKGROUND: End-stage renal disease (ESRD) complicates 5--10% of heart and heart--lung transplant patients. We report our experience of peritoneal dialysis (PD) in 17 such patients. METHODS: Between March 1995 and February 1999, 13 heart transplant and four heart--lung transplant patients (11 male, 6 female) joined our PD programme (10 continuous ambulatory PD, seven automated PD). Median time from heart or heart--lung transplantation to ESRD was 9 years (range 1--13 years), and median age at introduction of renal replacement therapy was 51 years (range 23--66 years). The frequency of exit-site infections, peritonitis, and PD survival (including technique failure and death) in the transplant group (TxP) was calculated retrospectively. These were compared with two contemporary control groups: PD patients immunosuppressed for other indications (ISP, n=19) and, all other patients recruited onto the PD programme (NISP, n=132). RESULTS: Median follow-up was 10 months (range 2--27 months) for TxP, 7 months (range 2--29 months) for ISP, and 14 months (range 1--48 months) for NISP groups. The frequency of exit-site infections was similar in each group: 1 in 26 months for TxP; 1 in 30 months for ISP, and 1 in 27 months for NISP (P=NS). The frequency of peritonitis was greater in the TxP group at 1 in 15 months, compared with 1 in 20 months for ISP and 1 in 29 months for NISP (TxP vs NISP, P<0.05). PD failure following infection was 23.5% for TxP, 10.5% for ISP, and 12.9% for NISP. Actuarial PD survival at 24 months was only 25.2% in the TxP group compared with 79% in the NISP group. There were no deaths related to immediate complications of PD. CONCLUSIONS: Increased risk of PD peritonitis and reduced PD survival is reported in this cohort of 17 heart and heart--lung recipients with ESRD. Nevertheless, for patients with severely impaired cardiac function, PD may still offer therapeutic advantage.

Adolescent↗
PubMed1996

Cyclosporin nephrotoxicity in heart and lung transplant patients.

Twenty-two patients with heart, lung or heart and lung transplants maintained on cyclosporin for periods ranging from 3 months to 10 years developed renal insufficiency which was investigated by renal biopsy. The histopathological changes were: (i) severe vascular and glomerular damage due to thrombotic microangiopathy (TM); (ii) a form of focal segmental glomerulosclerosis (FSGS); (iii) glomerular ischaemia. Rather than being separate entities, these changes appeared to represent a spectrum of pathology, some biopsies showing all three forms of glomerular injury. In all cases the glomerular changes were accompanied by arteriolar and arterial pathology, and we identified novel ultrastructural changes in the arteriolar endothelial basal lamina. Tubular atrophy was a consistent feature, the severity of which reflected the severity of the glomerular sclerosis, and which appeared to be a consequence of glomerular loss. Our findings are consistent with the nephrotoxic effects of cyclosporin being mediated chiefly via damage to preglomerular vessels and glomerular capillary endothelium. From an analysis of the clinical aspects of these cases, the effects of cyclosporin appear to be to some extent idiosyncratic, and therefore not entirely preventable, but strict monitoring of blood cyclosporin levels is essential to minimize the risk of permanent renal damage. Monitoring urinary protein in addition to plasma creatinine may detect the onset of FSGS, as proteinuria precedes creatinine elevation.

Adult↗
PubMed1994

Hepatitis C virus infection in haemodialysis patients: a clinical and virological study.

A cohort of 66 patients on maintenance haemodialysis was examined for serological (anti-HCV) and virological (HCV-RNA) evidence of infection with hepatitis C virus (HCV). Nine (13.6%) were anti-HCV positive, all of whom had detectable HCV-RNA in their serum. Statistical analysis of various risk factors (including length of time on haemodialysis, history of blood transfusion, history of renal transplantation and of previous hepatitis B infection) showed that only the length of time on haemodialysis was significantly associated with the acquisition of HCV infection. Genotypic analysis showed that five patients were infected with genotype 1 and a further two were infected with genotype 4. The latter finding is of significance because strains of genotype 4 are extremely uncommon in Western Europe. These results demonstrate that intra-unit transmission of HCV-infection took place in a group of patients on maintenance haemodialysis.

Aspartate Aminotransferases↗
PubMed1993

The effect of recombinant human erythropoietin on cardiovascular responses to postural stress in dialysis patients.

The normal response to 45 degrees head-up tilt (decreased stroke volume and cardiac output and increased heart rate and peripheral resistance) is not seen in the majority of haemodialysis patients. This is due to both an abnormal baroreceptor reflex and increased venous tone which may be explained by a number of factors including hypoxia, acidosis and sodium retention. We have studied this response by impedance cardiography in eight chronic haemodialysis patients, both before and after 3 months of treatment with human recombinant erythropoietin. Before treatment the cardiovascular parameters were abnormal both at rest and on tilting in each patient. The change in each measurement following tilting was: stroke volume, 0.5 +/- 6%; cardiac output, 6 +/- 5%; peripheral resistance, -8 +/- 4%; and heart rate, 10 +/- 4%. After 3 months of erythropoietin (150 U/kg/week intravenously) the mean haematocrit had risen from 19.5 +/- 3% to 32.9 +/- 4% and all patients felt physically fitter. Impedance showed no change in the supine-indices but after tilting there was a dramatic fall in stroke volume (-26 +/- 7%) and cardiac output (-17 +/- 7%) and an increase in heart rate (15 +/- 4%) and peripheral resistance (28 +/- 10%) each moving towards the normal response. These results indicate that human recombinant erythropoietin normalizes the response to postural stress in these patients and suggest that anaemia is the principal cause of the abnormal venoconstriction seen in haemodialysis patients. The mechanisms involved warrant further investigation.

Adult↗
PubMed1993

Can bio-electrical impedance be used to measure total body water in dialysis patients?

The measurement of total body water (TBW) by bio-electrical impedance (BEI) in a group of renal patients was evaluated against the tritium dilution method. The effect of haemodialysis and the presence of peritoneal dialysate on the impedance were also investigated. The correlation between the two methods was r = 0.9, with the standard deviation of the differences being 3.66 l (TBW typically 40 l). The BEI method overestimated the actual weight loss after haemodialysis, but underestimated the volume of peritoneal dialysate in situ. The BEI method would not be appropriate for use in assessing total body water and monitoring acute volume changes in patients with renal failure who are on strict fluid restriction.

Adult↗
PubMed1993

Determination of total body water in uraemic patients by bioelectrical impedance.

The measurement of total body water by bioelectrical impedance in a group of renal patients was evaluated against the tritium dilution method. The effect of haemodialysis and the presence of peritoneal dialysate on the impedance were also investigated. The correlation between the two methods is r = 0.90 with a residual standard deviation of 3.7. The standard deviation of the differences between the two methods against the means was 3.66 which means that total body water (TBW) estimated by the bioelectrical impedance (BEI) method may be 6.18 l (X +/- 2 SD) above or 8.38 l below the 3H2O method. The BEI method overestimated the actual weight loss after haemodialysis (3.87 +/- 1.7 l versus 2.43 +/- 1.8 l) but underestimated the volume of peritoneal dialysate in situ. The BEI method would not be appropriate for use in assessing total body water and monitoring acute volume changes in patients with renal failure who are on strict fluid restriction.

Adult↗
PubMed1992

High resolution proton magnetic resonance spectroscopy of cyst fluids from patients with polycystic kidney disease.

High field 1H-NMR spectra of fluid collected from the cysts of six renal transplant recipients with autosomal dominant polycystic kidney disease (ADPKD) have been measured and the major metabolite signals assigned. Quantitative NMR measurements have revealed a combination of unusual biochemical features of the cystic fluids that shows them to be distinct from both blood plasma and urine. Isoleucine, lysine, threonine and valine were present at mM concentrations, in cyst fluid and in some cases levels up to 2 orders of magnitude higher than normal plasma or urine were recorded. Mean glucose concentrations in the cyst fluids ranged from 3.4-9.6 mM and a number of organic acids and bases, including acetate, lactate, succinate, creatinine and dimethylamine were also present at high concentration and in different ratios to those found in either plasma or urine. The majority of cyst fluids examined also contained significant quantities of glycoproteins with characteristic 1H-NMR signals from N-acetyl groups of amino-sugar and sialic acid side chains which had a high degree of molecular mobility (as indicated by their relatively long T2 relaxation times, greater than 120 ms). High levels of ethanol (0.5-12.6 mM/l) were found in all fluid samples from the six transplanted patients (confirmed by conventional analysis). In general there was little variation in the 1H-NMR spectral patterns of either the intra- or interpatient cyst fluids, although the contribution of the protein macromolecules to individual spectra was lower in a few cysts. This constancy of biochemical composition probably reflects the chronic nature of the accumulation of cyst fluid and a long turnover of the cystic fluid components which has the effect of averaging composition. These findings suggest that the dynamic composition of cyst fluid from ADPKD patients is unique among the other body fluids and that the unusual composition may be related to epithelial polarity reversal of the cystic epithelium which could also contribute to the growth of the cysts.

Amino Acids↗
PubMed1990

Cardiac output and oxygen uptake in patients with renal failure.

1. Cardiac index, oxygen uptake and haemoglobin concentration have been measured in eight patients with end-stage renal failure, and the values compared with those in eight healthy control subjects. Assuming the arterial blood to be 97% saturated, the oxygen saturation of mixed venous blood has been calculated. 2. Cardiac index was lower in the patients (2.45 +/- 0.42 litres min-1 m-2) compared with the control subjects (3.74 +/- 0.17 litres min-1 m-2). Oxygen uptake was reduced from 147 +/- 16 ml STP min-1 m-2 in the control subjects to 112 +/- 9 ml STP min-1 m-2 in the patients. 3. Oxygen saturation of mixed venous blood was 53 +/- 8% in the patients compared with 79 +/- 2% in the control subjects, suggesting some degree of tissue hypoxia. If oxygen uptake were not reduced in renal failure, then the mixed venous blood oxygen saturation would be as low as 40%. 4. The oxygen saturation of blood sampled from the superior vena cava of patients with renal failure was 57 +/- 6%. 5. The data on oxygen uptake and venous oxygen saturation suggest that in the patients with end-stage renal failure, the low values of cardiac index, previously measured by impedance cardiography, are accurate.

Adult↗
PubMed1990

Hemodynamic responses to head-up tilt in uremic patients.

The hemodynamic responses to 45 degrees C head-up tilt for 30 min were compared between a group of 13 normal healthy subjects, 16 patients with end-stage renal failure (Group 1) and 9 hypertensive patients (Group 2). In the normal subjects there was no change in systolic blood pressure (SBP), a significant increase in diastolic blood pressure (DBP) (9 +/- 1 mmHg, mean + SEM, p less than 0.01), heart rate (HR) (11 +/- 2 beats/min) and derived peripheral resistance (PR) (66 +/- 8%, p less than 0.001). Stroke volume (SV) and cardiac output (CO) fell significantly by 42 +/- 3% and 33 +/- 3%, respectively. The responses in Group 2 patients were similar to those of the controls. However in Group 1 patients, though there was a rise in heart rate (9 +/- 2, p less than 0.001), SBP fell significantly accompanied by no change in either DBP or PR. The decrease in SV was only 12 +/- 4% while there was no change in derived CO. The results suggest that there was a lack of vasoconstriction during postural stress in patients with endstage renal failure, which was probably due to a functional defect in the baroreceptor reflex. Concomitantly, the small decrease in SV suggests stiffness of the veins and/or active venoconstriction which may help to prevent a bigger fall in blood pressure.

Adult↗
PubMed1989

Treatment of resistant CAPD peritonitis by temporary discontinuation of peritoneal dialysis.

Resistant continuous ambulatory peritoneal dialysis (CAPD) peritonitis (recurrent or persistent infection) is traditionally treated by removal of the CAPD catheter and a period off peritoneal dialysis. In a pilot study we have treated 8 patients with recurrent staphylococcal peritonitis and 3 patients with persistent staphylococcal peritonitis by stopping CAPD for a 2-week period, the CAPD catheter being left in-situ. All 8 patients with recurrent peritonitis and 2 of the 3 patients with persistent peritonitis had resolution of their infection; the third patient required catheter removal to clear the infection. There were no acute problems associated with stopping CAPD, and there was no evidence of loss of peritoneal filtration capacity on restarting CAPD. This novel approach to the treatment of resistant CAPD peritonitis should reduce the number of CAPD catheters replaced and therefore diminish the risks and inconvenience to patients that such replacements entail.

Catheters, Indwelling↗
PubMed1986

Effect of 2 liters of intraperitoneal dialysate on the cardiovascular system.

In 21 patients receiving continuous ambulatory peritoneal dialysis (CAPD), the effect of 2 liters of intraperitoneal dialysate on the supine and upright hemodynamics (19 patients), and the hemodynamic responses to 45 degrees head-up tilt (9 patients) were studied. Blood pressure (BP), heart rate (HR) and stroke volume (SV) (using impedance cardiography) were measured. In the supine position there was no significant difference in BP, SV, HR, derived cardiac output (CO) and peripheral resistance (PR) between "empty" (E) and "full" (F) conditions. On standing in both E and F conditions there were significant falls in systolic BP (p less than 0.001, compared with supine), SV and CO (p less than 0.05) accompanied by an increase in HR (p less than 0.001) but no significant change in peripheral resistance nor diastolic BP. The fall in systolic BP was greater in the E condition (from 149.3 +/- 4.5 mmHg to 134.6 +/- 5.9 in E, from 148.8 +/- 4 mmHg to 140.8 +/- 5.0 in F, p less than 0.001) and was accompanied by a bigger rise in HR (from 80.2 +/- 4.3 beat/min to 91.8 +/- 5.3 (E), from 79.4 +/- 4.4 to 87.7 +/- 5.2 (F, p less than 0.001). On tilting in 13 normal subjects there was an increase in diastolic BP (76.7 +/- 2.0 mmHg to 81.4 +/- 0.6, p less than 0.01), HR (63.3 +/- 2.4 beat/min to 73.6 +/- 1.0, p less than 0.01) and PR (13.4 +/- 1.0 mmHg/l/min to 21.3 +/- 0.2, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Fluid removal by haemofiltration in diuretic resistant cardiac failure.

A 60 year old woman with diuretic resistant cardiac failure was treated with intermittent haemofiltration before tricuspid valve replacement. This technique can remove large quantities of fluid rapidly, thus controlling oedema and allow appropriate fluid replacement. Haemofiltration is thus a simple and safe method of managing unresponsive oedema in cardiac failure sometimes allowing corrective cardiac surgery.

Blood↗