Sympathetic nerve activity is inappropriately increased in chronic renal disease

The hypothesis that in hypertensive patients with renal parenchymal disease sympathetic activity is "inappropriately" elevated and that this overactivity is a feature of renal disease and not of a reduced number of nephrons per se is addressed. Fifty seven patients with renal disease (various causes, no diabetes, all on antihypertensive medication) were studied, age range 18 to 62, creatinine clearance 10 to 114 ml/min per 1.73 m(2). Antihypertensives were stopped, but diuretics were allowed, to prevent overhydration. Matched control subjects were also studied. The effect of changes in fluid status was examined in seven patients while on and after stopping diuretics and in eight control subjects while on low- and high-sodium diet. Seven kidney donors were studied before and after unilateral nephrectomy. Sympathetic activity was quantified as muscle sympathetic nerve activity (MSNA) in the peroneal nerve. Mean arterial pressure, MSNA, and plasma renin activity were higher in patients than in control subjects, respectively (115 +/- 12 and 88 +/- 11 mmHg, 31 +/- 15 and 18 +/- 10 bursts/min, and 500 [20 to 6940] and 220 [40 to 980] fmol/L per s; P < 0.01 for all items). Extracellular fluid volume (bromide distribution) did not differ. Seven patients were studied again after stopping diuretics. MSNA decreased from 34 +/- 18 to 19 +/- 18 bursts/min (P < 0.01). Eight healthy subjects were studied during low- and high-sodium diet. MSNA was 26 +/- 12 and 13 +/- 7 bursts/min (P < 0.01). The curves relating extracellular fluid volume to MSNA were parallel in the two groups but shifted to a higher level of MSNA in the patients. In the kidney donors, creatinine clearance reduced by 25%, but MSNA was identical before and after donation. It is concluded that in hypertensive patients with renal parenchymal disease, sympathetic activity is inappropriately high for the volume status and that reduction of nephron number in itself does not influence sympathetic activity.     

Causes of pleural exudates in a region with a high incidence of tuberculosis

OBJECTIVE: To define the causes of exudative pleural effusions in our region. METHODOLOGY: A retrospective study was performed on consecutive patients with exudative pleural effusion seen in our hospital during a 4-year period. RESULTS: Of 186 patients with a mean age (+/- SD) of 51.2 (+/- 19.2) years with exudative pleural effusions, 131 (70.4%) were males and 55 (29.6%) were females. The most frequent cause of exudative pleural effusions was tuberculosis (44.1%), followed by malignancy (29.6%). The majority (94.5%) of malignant pleural effusions were due to lung cancer. Apart from a patient with bilateral pleural effusions due to cryptococcosis, patients with tuberculous pleural effusion (mean age (+/- SD), 39.7 (+/- 17.5)) were significantly younger than the rest (P < 0.05). Tuberculous effusions were most frequent in the first five decades (60/82, 73.2%) and were the most common type of pleural effusion, accounting for 60 (69.8%) of 86 cases, in this age range. Malignant effusions were more frequent among the older age groups, 74.5% (41/55) of patients with malignant effusions being older than 50 years. Most types of pleural effusions showed a preference for the right side. Of the 44 cases of large effusions, 28 (63.6%) were caused by malignancy. CONCLUSIONS: In our region with a high incidence of tuberculosis, the most frequent cause of pleural exudates is tuberculosis followed by malignancy, particularly lung cancer.     

An economic analysis of email-based telemedicine: A cost minimisation study of two service models

Background  

Email-based telemedicine has been reported to be an efficient method of delivering online health services to patients at a distance and is often described as a low-cost form of telemedicine. The service may be low-cost if the healthcare organisation utilise their existing email infrastructure to provide their telemedicine service. Many healthcare organisations use commercial-off-the-shelf (COTS) email applications. COTS email applications are designed for peer-to-peer communication; hence, in situations where multiple clinicians need to be involved, COTS applications may be deficient in delivering telemedicine. Larger services often rely on different staff disciplines to run their service and telemedicine tools for supervisors, clinicians and administrative staff are not available in COTS applications. Hence, some organisations may choose to develop a purpose-written email application to support telemedicine. We have conducted a cost-minimisation analysis of two different service models for establishing and operating an email service. The first service model used a COTS email application and the second used a purpose-written telemedicine application.