Hypotensive ischemic optic neuropathy and peritoneal dialysis.

PURPOSE: To report anterior ischemic optic neuropathy associated with systemic hypotension in a patient undergoing continuous ambulatory peritoneal dialysis. METHODS: Case report. A 58-year-old man undergoing continuous ambulatory peritoneal dialysis developed painless blurred vision in both eyes and bilateral optic disk swelling with an altitudinal field defect in the left eye. Twenty-four-hour ambulatory blood pressure monitoring was requested in addition to other routine investigations. RESULTS: Routine blood pressure measurement in the clinic was 130/86 mm Hg, but ambulatory blood pressure monitoring demonstrated pronounced early morning hypotension with individual readings as low as 91/41 mm Hg. CONCLUSIONS: Renal dialysis can render patients hypotensive, and this may be associated with anterior ischemic optic neuropathy. The overnight drop in blood pressure may not be appreciated with routine blood pressure measurement. Therefore, 24-hour ambulatory blood pressure monitoring should be considered when investigating patients with suspected anterior ischemic optic neuropathy who are undergoing renal replacement.

End-stage renal failure in adults with the tuberous sclerosis complex.

BACKGROUND: Tuberous sclerosis (TSC) is a multisystem disorder encompassing a wide spectrum of pathological renal lesions. Renal involvement is commonly asymptomatic but can result in significant morbidity, and renal failure has been reported. The risk of renal failure in patients with TSC in the UK has not been defined. METHODS: A survey of the 170 members of the European Dialysis and Transplant Association was carried out to identify and collect clinical information on patients with TSC in their renal replacement programme. RESULTS: Ten patients were identified as having end-stage renal failure (ESRF) and TSC, giving an incidence of 1% in patients with TSC and normal intellect. There was a wide spectrum of underlying pathology and clinical presentation within this group. CONCLUSION: ESRF is rare in TSC but does contribute to significant morbidity and mortality in this group.

Use of in vitro models of haemofiltration and haemodiafiltration to estimate dosage regimens for critically ill patients prescribed cefpirome.

BACKGROUND: The physico-chemical properties of cefpirome (low protein binding, high water solubility and low molecular weight) suggest that it may be lost readily from the extracorporeal circulation of intensive care unit patients during continuous renal replacement therapy. METHOD: In order to make informed dosage recommendations for patients receiving artificial renal support, cefpirome loss from human blood has been quantified using in vitro models of continuous haemofiltration and haemodiafiltration. Cefpirome clearance was measured using three membrane types at varying ultrafiltrate (UFR) and dialysis flow rates (Qd). RESULTS: During haemofiltration cefpirome was found to cross hollow fibre polyamide (PA) and polyacrylonitrile (PAN) membranes with equal efficiency. The mean sieving coefficients (S) of both PA and PAN membranes were consistently high (> 0.7) when two different ultrafiltration rates were used. Changing the ultrafiltration rate or membrane type had no significant effect on the sieving coefficient of cefpirome but did result in an increase in cefpirome filter clearance (Fcl). Using the haemodiafiltration model, cefpirome penetrated PAN membranes (flat plate AN69S) more efficiently than hollow fibre PA membranes (FH66D). In each case, increasing the dialysis flow rate reduced the S-value. However, although increasing Qd was associated with a greater Fcl of cefpirome when PAN membranes were employed, no such relationship was found for the PA hollow fibre membrane. CONCLUSION: The information generated can be used to estimate a dosing regimen for intensive care patients prescribed cefpirome and receiving continuous renal replacement therapy.

Pharmacokinetics of opioids in renal dysfunction.

Patients with renal insufficiency commonly require the administration of an opioid analgesic to provide adequate pain relief. The handling of morphine, pethidine (meperidine) and dextropropoxyphene in patients with renal insufficiency is complicated by the potential accumulation of metabolites. While morphine itself remains largely unaffected by renal failure, accumulation, as denoted by an increase in both mean peak concentrations and the area under the concentration-time curve, of both the active metabolite (morphine-6-glucuronide) and the principal metabolite (morphine-3-glucuronide, thought to possess opiate antagonist properties) have been reported. The increased elimination half-lives of the toxic metabolites norpethidine and norpropoxyphene in patients with poor renal function administered pethidine and dextropropoxyphene, respectively, makes their routine use ill advised. Case reports of prolonged narcosis associated with the use of both codeine and dihydrocodeine in patients with renal insufficiency call for care to be used when prescribing these agents under such conditions. Although the pharmacokinetics of buprenorphine, alfentanil, sufentanil and remifentanil change little in patients with renal failure, the continuous administration of fentanyl can lead to prolonged sedation.

Thrombo-embolic disease after splenectomy for hereditary stomatocytosis.

Nine cases of hereditary stomatocytosis (HSt) are presented which show documented thrombotic complications after splenectomy. In three cases, patients became severely ill with pulmonary hypertension and a fourth developed portal hypertension. One unsplenectomized affected adult relative had suspected but unconfirmed thrombotic pathology; the six other affected unsplenectomized adults did not. Since splenectomy is of only limited therapeutic benefit in stomatocytosis, it should not be performed without careful consideration. A tendency to iron overload, even without hypertransfusion and irrespective of splenectomy, is evident in many of these patients.

Renal replacement therapy in the ICU: the role of continuous arteriovenous haemodialysis.

Conventional haemodialysis is not available on all intensive care units (ICUs) and there are relatively few renally trained nurses able to run haemodialysis machines. Continuous arteriovenous haemodialysis provides effective renal replacement therapy for critically ill patients in the ICU. Unlike continuous arteriovenous haemofiltration it provides sufficient control over electrolyte, solute and water balance to obviate the need for additional treatment with intermittent conventional haemodialysis.

Effect of lithium carbonate therapy on thyroid immune status in manic depressive patients: a prospective study.

Serum thyroid autoantibodies to thyroglobulin (TG) and thyroid microsomes (M) were measured by ELISA prospectively in 37 manic depressive patients prior to receiving lithium carbonate and during therapy with this drug for a mean of 16.2 months. They were also measured once in 27 normal subjects and several times in five psychiatric patients not receiving lithium. Sixteen patients (43%) had either thyroglobulin, microsomal antibodies or both before receiving lithium therapy. During therapy significant fluctuations in antibody titre, both upwards and downwards were observed in ten out of 12 patients with M antibodies and in nine out of 11 with TG antibodies. The fluctuations in antibody titre are consistent with an immunomodulatory effect of lithium as has been shown in animal studies. It is suggested that psychiatric patients should have thyroid antibodies measured routinely before and during lithium therapy.

Ten years' experience of an amyloid clinic--a clinicopathological survey.

The aetiology, clinical course and affected organs were studied in 124 patients with acquired systemic amyloidosis and seven patients with organ-limited amyloid deposits. Seventy-five patients had reactive systemic AA amyloidosis, which was associated with rheumatic disease in 55 and with chronic infection in 13 cases. Forty-nine patients had systemic AL amyloidosis. Thirteen of these cases were associated with myelomatosis and 11 with non-malignant immunocyte dyscrasias. In 25 patients with systemic AL disease no immunocyte dyscrasia was identified. Renal involvement dominated the clinical course of both forms of systemic amyloidosis, and renal failure was the most common cause of death. Gastrointestinal disturbance and hepatosplenomegaly were found in both AA and AL disease, although differences were noted in the distribution of amyloid protein within rectal biopsies. Amyloid cardiomyopathy, neuropathy and macroglossia were present in patients with AL amyloidosis only. These clinical patterns were reflected by tissue distribution at necropsy in 67 patients.

A receptor assay for the measurement of TSH receptor antibodies in unextracted serum.

A receptor assay for TSH receptor antibodies is described in which unextracted serum, detergent solubilised TSH receptors and 125I-labelled TSH are used. The assay was rapid and reproducible with coefficients of inter-assay variation of 12.3%, 2.1 and 2.6% at mean inhibition of TSH binding values of 11, 53, and 79 respectively. Assay sensitivity could be increased by reducing the volume of receptors used but some increase in the scatter of values obtained with individual normal sera was also observed. Comparison of human and porcine TSH receptor preparations indicated that porcine tissue gave greater sensitivity. Analysis of different groups of patients and normal subjects (n = 21) showed the absence of detectable TSH receptor antibody activity in 16 patients with rheumatoid arthritis, 10 with multinodular goitre and 12 with Hashimoto's disease. However the antibody was readily detectable in 28 out of 28 Graves' patients (treated and untreated) who were hyperthyroid at the time of assay.

Renal involvement in systemic amyloidosis.

In a study of 124 patients with systemic amyloidosis, renal involvement was the major presenting feature in 68 per cent of patients with AA and 42 per cent with AL disease. Renal failure contributed to the deaths of 72 per cent and 33 per cent of patients respectively. In 23 renal biopsies from patients with AA disease, quantitative glomerular amyloid infiltration correlated with urinary protein excretion and with serum creatinine. Seven of these patients had repeat biopsies; change in glomerular amyloid correlated with changes in both renal function and proteinuria. Four patients with end-stage renal amyloidosis have been successfully managed on CAPD for 37 patient months.