Analysis of rt-PA infusion in tunnelled dialysis catheters.

Urokinase and streptokinase are commonly used thrombolytic agents for obstructed central venous catheters. Although proven to be efficacious, these agents have the potential to induce fibrin breakdown and streptokinase cannot be used repeatedly due to its allergenic nature. Documented evidence suggests that urokinase is safe and effective (> 70% efficacy for catheter installation) however further evidence points to tissue-type plasminogen activator (rt-PA) achieving as much as 98% success. This study reports on the safety and efficacy of alternative catheter thrombolysis, namely rt-PA and evaluates the efficacy of rt-PA. 20 patients required 57 infusions in 38 lumens between 01/01/02 to 01/09/03. For completely blocked lines rt-PA was infused at 2 mg/hr for 4 hours achieving 85% success rate. For inadequate flow (< 250 mls/min) rt-PA was infused at 1 mg/hr for 4 hours achieving 88% success rate.

Substance abuse and the kidney.

Substance abuse has been increasing steadily in the UK and some other countries. Recent evidence suggests more than 40% of young people have tried illicit drugs at some time. There are numerous medical consequences to recreational drug use, and a physician should always consider substance abuse in any unexplained illness. The renal complications of drug abuse are also becoming more frequent, and may encompass a spectrum of glomerular, interstitial and vascular diseases. Although some substances are directly nephrotoxic, a number of other mechanisms are also involved. These effects are often chronic and irreversible, but occasionally acute with possible recovery. The rapid growth of illicit drug use is clearly a major public health problem. We review the commonly used substances of abuse and their associations with renal disease.

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.

Pregnancy does not adversely affect renal transplant function.

Women with functioning transplanted kidneys often become fertile again. Indeed, renal function, endocrine status and libido rapidly improve after renal transplantation, and 1:50 women of childbearing age become pregnant. However, there is concern regarding the haemodynamic changes of pregnancy, which could lead to a decline in graft function (temporary or permanent). We examined obstetric data and renal parameters in 29 patients and 33 pregnancies. Mean serum creatinine and creatinine clearance remained stable throughout pregnancy and 1 year postpartum. However, there was a significant increase in proteinuria from a mean of 0.45 g/24 h around the time of conception to 1.11 g/24 h at delivery (p<0.05). The proteinuria resolved to baseline levels at 3 months postpartum. We highlight certain parameters to be considered before conception to allow a good obstetric outcome and prolong stable renal function: serum creatinine <150 micromol/l, proteinuria <1 g/day, absence of histological evidence of chronic allograft rejection, controlled blood pressure (140/90) and stability of maintenance immunosuppression.

Tracheal stenosis in Larsen's syndrome.

Larsen's syndrome is known to have an association with laryngomalacia and tracheomalacia. We report a case of Larsen's syndrome with respiratory difficulty due to a tracheal stenosis. To our knowledge, this association has not previously been reported.

The management of hyperkalaemia in the emergency department.

Life threatening hyperkalaemia (> 7.0 mmol/l) is commonly associated with acute renal failure. Moderate hyperkalaemia (6.1-6.9 mmol/l) is also common and well tolerated in patients with chronic renal failure. Renal failure is the most common cause of hyperkalaemia although other causes to consider include drugs (potassium sparing diuretics, angiotensin converting enzyme inhibitors), hyperglycaemia, rhabdomyolysis and adrenal insufficiency. Hyperkalaemia affects the cardiac conducting tissue and can cause serious arrhythmias including ventricular fibrillation and asystolic arrest. Therefore it is important to treat hyperkalaemia promptly in the emergency department. This paper evaluates the therapeutic options available for treatment of hyperkalaemia.

Restoration of flow following haemodialysis catheter thrombus. Analysis of rt-PA infusion in tunnelled dialysis catheters.

PROBLEM: Urokinase and streptokinase are commonly used thrombolytic agents for obstructed central venous catheters. Although proven to be efficacious, these agents have the potential to induce fibrin breakdown and streptokinase cannot be used repeatedly because of its allergenic nature. Published evidence suggests that Urokinase is safe and effective (>70% efficacy for catheter installation) and that Tissue-type plasminogen activator (rt-PA) can achieve as much as 98% success. OBJECTIVE: To describe our experience with and our protocol for the use of rt-PA as an alternative agent for catheter thrombolysis. DESIGN: Investigation of a cohort of haemodialysis patients with tunnelled central venous catheter (SPCVC) placed between December 2001 to August 2003 and who developed catheter thrombus (female, n = 8: male, n = 12). Each patient was given an infusion of between 1 and 2 mg rt-PA/h for 4 h. The dose was dependent on partial or total line obstruction. The technical success of rt-PA is defined as returning catheter blood flow to >250 mL/min for a 4-h period. FINDINGS: Twenty patients required 57 infusions in 38 lumens between 01/01/02 to 01/09/03. For completely blocked lines rt-PA was infused at 2 mg/h for 4 h achieving 85% success rate. For inadequate flow (<250 mL/min) rt-PA was infused at 1 mg/h for 4 h achieving an 88% success rate. CONCLUSION: Rt-PA administered at 2 mg/h for blocked lines effectively restores haemodialysis catheter patency, and at 1 mg/h for sluggish lines is also effective in restoring blood flow through catheters.