Underutilization of aspirin in hemodialysis patients for primary and secondary prevention of cardiovascular disease

BACKGROUND

Patients on hemodialysis are at high risk for cardiovascular disease (CVD). Aspirin is an established therapy for primary and secondary prevention of CVD that may be underutilized in hemodialysis patients. To better understand the use of aspirin in hemodialysis patients, we examined the experience of an urban hemodialysis center. Guidelines for use as well as associated risks and benefits are reviewed.

METHODS

Medical records for patients receiving hemodialysis treatment at our center (New York City, USA) in May 2004 were reviewed for aspirin use, presence of CVD, and potential contraindications to aspirin therapy. CVD was defined as a history of coronary artery disease, ischemic stroke, transient ischemic attack, or peripheral vascular disease. Potential contraindications to aspirin therapy included history of clinically significant bleeding or increased risk of bleeding, aspirin allergy and routine treatment with other anticoagulants.

RESULTS

176 patients were eligible for the study and 172 (98%) were included. Although 74 patients had a history of CVD, only 38 (51 %) of these were treated with aspirin. Among patients with a history of CVD who were not treated with aspirin, 19 (53%) had no identifiable contraindications to aspirin therapy for secondary prevention of CVD. Ninetyeight patients had no history of CVD, and 18 (18%) of these were treated with aspirin. Of patients without a history of CVD who were not treated with aspirin, 57 (71%) had no identifiable contraindications to aspirin therapy for primary prevention of CVD.

CONCLUSIONS

Aspirin is underutilized in hemodialysis patients for the primary and secondary prevention of CVD. Given the high risk of CVD in hemodialysis patients, therapy with aspirin may be of significant benefit and prospective studies of aspirin therapy are needed.

Increasing incidence of focal segmental glomerulosclerosis and an examination of demographic patterns

BACKGROUND

Idiopathic focal segmental glomerulosclerosis (FSGS) is one of the leading causes of the nephrotic syndrome in adults and an important cause of end-stage renal disease. Its incidence has dramatically increased in the last two decades and it is especially prevalent among black patients. The trend of FSGS incidence has not been reported beyond 1997.

METHODS

We retrospectively reviewed all renal biopsies performed at our institution between 1986 and 2002 and identified patients with diagnoses consistent with primary glomerulopathy (PG), which included: minimal-change disease (MCD), idiopathic focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MGN), IgA nephropathy (IgA), membrano-proliferative glomerulonephritis (MPGN) and mesangioproliferative glomerulonephritis. Patients with possible secondary causes for their renal disease were excluded. Clinical data at the time of biopsy and follow-up data were collected and analyzed.

RESULTS

During the period from January 1986-December 2002, 299 renal biopsies were performed and 132 patients were diagnosed with PG. FSGS was the most common form of PG representing 37.8% of all PG followed by IgA 27.3%, MGN 16.6% and MCD 9.1%. Among FSGS patients 59% were females, 64% had nephrotic range proteinuria and 54% had the nephrotic syndrome. Mean serum creatinine was 2.0 +/- 0.2 mg/dl and mean protein excretion was 6.1 +/- 1.0 g/day. The incidence of FSGS increased from 19.3% (1986-1991) and 16.6% (1992-1997) to 58.5% in the period from 2002. The increase occurred among black and Hispanic patients (33.3-79.2%) as well as white patients (12.5-51.5%). Black and Hispanic patients with PG presented for renal biopsy at a significantly younger age than white patients (p = 0.003), with mean age 37.5 +/- 2.0 years vs. 50.3 +/- 1.8 years. White FSGS patients were significantly older than white non-FSGS patients (mean age 56.4 +/- 3.2 years vs. 48.0 +/- 2.0 years, p = 0.03). Black and Hispanic FSGS patients were also older when compared to their non-FSGS counter-parts (mean age 40.6 +/- 2.8 years vs. 32.1 +/- 2.0 years, p = 0.04). When patients were stratified by age (< 45 years and > or = 45 years), FSGS was the most common diagnosis in both age groups among black and Hispanic patients (55.1% and 88.8%) but only among older white patients (36.2%).

CONCLUSIONS

The incidence of FSGS as a proportion of PG in our population has increased markedly in the most recent time period analyzed (1998-2002). The increase has occurred among both white and black and Hispanic patients. We also found that FSGS was most prevalent in patients > or = 45 years.

Targeting higher ferritin concentrations with intravenous iron dextran lowers erythropoietin requirement in hemodialysis patients

INTRODUCTION

Although clinical use of recombinant human erythropoietin (rHuEPO) since 1989 has improved anemia in most end-stage renal disease patients, there are still many hemodialysis patients unable to maintain an adequate hematocrit (HCT) without large doses of rHuEPO. This suggests that anemia is not solely a consequence of rHuEPO deficiency, but may be due to other factors including functional iron deficiency. Since the optimal prescription for iron replacement is not yet known, we evaluated the effect of intravenous iron dextran (IVFe) infusion on serum ferritin (SFer) concentration and rHuEPO dose. Our objective was to raise and maintain serum ferritin concentrations to 2 different levels above the National Kidney Foundation Dialysis Outcome Quality Initiative standard of 100 ng/ml to determine whether, and by what degree rHuEPO dose could be lowered.

METHODS

HD patients on i.v. rHuEPO with a SFer concentration > or = 70 ng/ml and an HCT of < or = 33% were enrolled. Subjects were divided as follows: Group 1: target SFer of 200 ng/ml, Group 2: target SFer of 400 ng/ml. Each subject below the target level received IVFe in up to 10 divided doses during consecutive dialysis sessions as needed to reach the target. HCT was maintained between 32.5% and 36% by adjusting rHuEPO dosage.

RESULTS

Mean SFer concentration at the study conclusion in Group 1: 261 ng/ml; Group 2: 387 ng/ml. The mean decrease in rHuEPO dose for Group 1 was 31 U/kg body weight/week (250 - 219 U/kg bw/wk) while in Group 2 it was 154 U/kg body weight/week (312 - 158 U/kg bw/wk) (p < 0.001). There was no difference in HCT between groups. Our results suggest that higher target serum ferritin concentrations can be well tolerated and lower rHuEPO requirements.

Combined converting enzyme inhibition and angiotensin receptor blockade reduce proteinuria greater than converting enzyme inhibition alone: insights into mechanism

Patients with various renal diseases receiving an angiotensin-converting enzyme inhibitor (CEI) were enrolled in a protocol to determine whether adding an angiotensin type 1 receptor blocker (ARB) reduces urinary protein excretion (UPE). All patients had significant proteinuria (range 517-8,562 mg/24 h) despite administration of CEI for at least 4 weeks. Following baseline measurements, losartan (50 mg/d) was started and testing was repeated at 1 month. Compared with CEI alone, combined CEI plus ARB reduced UPE by 45 +/- 8% (p < 0.005). Compared with CEI alone, CEI + ARB lowered UPE in each patient independent of baseline protein excretion or renal diagnosis. Reduction in proteinuria occurred independent of changes in mean arterial blood pressure (MAP), suggesting that the mechanism involved local changes in glomerular dynamics. If renal angiotensin II (ANG II) formation occurred despite CEI, the ANG II formed would suppress plasma renin activity (PRA), and adding an ARB would cause PRA to rise. In 7 of 10 subjects, addition of ARB to CEI increased PRA (p < 0.03) suggesting that intrarenal ANG II formation occurred in CEI-treated subjects. As a second marker of ANG II tissue activity, we measured the effects adding ARB on plasma aldosterone (ALDO). In 9 of 10 subjects, ALDO was acutely lowered (p < 0.009) suggesting that ANG II levels were incompletely blocked by CEI. We conclude that: combined CEI and ARB reduces UPE greater than CEI alone; reduction in proteinuria is independent of changes in MAP or renal diagnosis; and the additive effects of CEI and ARB are due at least in part to greater inhibition ofANG II action at the tissue level in the kidneys and adrenal glomerulosa.

Assessment of sonographic venous peak systolic velocity in detecting hemodialysis arteriovenous graft stenosis

There is no single effective means of assessing arteriovenous access function, although monitoring hemodialysis venous pressure (VP) or measuring access recirculation may be of some benefit. The present study assesses prospectively the efficacy of following the peak systolic velocity (PSV) as a single measure to detect arteriovenous graft (AVG) stenosis. PSV was measured in 12 patients after new AVG placement and at approximately 2-month intervals. Angiography was also performed after new graft placement and when PSV was elevated to greater than 200 cm/sec, hemodialysis access VP increased to greater than 150 mm Hg on three consecutive readings, or access recirculation increased to greater than 11%. PSV was then compared with results from angiography, VP monitoring, and access recirculation. The 12 patients underwent 34 PSV studies, followed by angiography on 25 occasions. Each patient underwent at least one angiogram. Each abnormal PSV value was confirmed with the finding of stenosis on angiogram, except for two patients with PSVs greater than 400 cm/sec and normal angiography results. VP and recirculation were not elevated. During this period, two patients developed thrombosis of the AVG, and two patients underwent angioplasty with improvement in PSV. We conclude that elevations in PSV measured at the venous anastomosis are an effective means of screening for AVG stenosis, AVG stenosis can occur early after AVG placement, and elevated VP and recirculation are late findings in AVG dysfunction.

Body composition assessed by neutron activation analysis in dialysis patients

Malnutrition is prevalent in end-stage renal disease (ESRD) patients treated with hemodialysis (HD) and peritoneal dialysis (PD). In addition, there is increased incidence of morbidity in this group. Evaluation of nutritional status is important. Application of body composition in the ESRD population to evaluate body compartments and to assess nutritional health has become more common in clinical practice. Neutron activation analysis (NAA) may provide data on metabolically active tissue by quantification of total body potassium (TBK) for body cell mass and assessment of protein by total body nitrogen (TBN). This method may be able to detect changes in body composition before clinical signs of malnutrition are apparent. Ten HD (5 male and 5 female) and 10 PD patients (7 male and 3 female) were evaluated by NAA, TBK, and isotope dilution. Female PD patients had an increased total body water (TBW) and increased intracellular water compared to HD females. Albumin was lower in PD women. There was no significant difference between PD men and laboratory controls in TBW, extracellular water, and TBN. The clinical application of body composition methods for evaluation of dialysis patients by serial assessment and for development of a bedside tool needs further study.

Renin-aldosterone system can respond to furosemide in patients with hyperkalemic hyporeninism

Thirty-four patients (65.3+/-3.3 years of age, mean+/-SEM) with hyperkalemia (serum potassium >5.0 mEq/L) had measurement of their renin-aldosterone system. Nineteen patients (56%) had plasma renin activity (PRA) >1.5 ng/mL/h, which was not low, while 15 (44%) had PRA <1.5. Twelve of the 15 hyporeninemic hyperkalemic patients were studied to determine whether their renin-aldosterone system responded to 2 weeks of furosemide, 20 mg daily. Four were nonresponders: PRA averaged 0.3+/-0.1 ng/mL/h, and it did not increase with furosemide or respond to captopril before or after furosemide. Eight patients were responders: PRA averaged 0.6+/-0.2 ng/mL/h and increased with furosemide to 5.5+/-3.4 ng/mL/h. Captopril failed to increase PRA before furosemide, but PRA increased to 15.3+/-8.4 ng/mL/h after furosemide. Plasma aldosterone was low in both nonresponders and responders (3.5+/-1.2 ng/dL vs 5.8+/-2.5 ng/dL) and did not increase significantly with furosemide (4.3+/-1.7 ng/dL vs 8.7+/-2.5 ng/dL). Serum potassium did not fall and therefore did not limit the rise in aldosterone. Renin responders had greater body weight, were predominantly female (6/8 vs 2/4) and were more likely to have diabetes mellitus (7/8 vs 0/4). Plasma atrial natriuretic peptide (ANP) fell with furosemide in 8 of 8 responders and in 1 of the 2 nonresponders in whom it was measured. Neither group had suppressed plasma prorenin levels, indicating no suppression of renin gene expression. These results indicate that many hyperkalemic patients do not have suppressed PRA. Further, a majority of patients with suppressed PRA have high levels of ANP and can respond to diuretic therapy with a rise in PRA and a fall in ANP, suggesting physiologic suppression of the renin system by volume expansion. A minority of hyperkalemic patients with suppressed PRA had PRA that did not increase under these study conditions.

Percentage body fat determination in hemodialysis and peritoneal dialysis patients: a comparison

OBJECTIVE

To evaluate percentage body fat in hemodialysis (HD) and peritoneal dialysis (PD) patients.

DESIGN

A prospective study of 20 HD patients and 20 PD patients.

SETTING

Sol Goldman Renal Therapy Center, Lenox Hill Hospital, New York, NY; Baumritter Kidney Center Albert Einstein College of Medicine, Bronx, NY; Body Composition Unit, St Luke's Roosevelt Hospital, Columbia University, New York, NY.

PATIENTS

Twenty HD (10 men, 10 women) patients, mean age 41.8 +/- 2.4 years and 20 PD (12 men, 8 women) patients, mean age 48.6 years +/- 3.0 years.

INTERVENTION

This is a noninterventional study. PATIENTS signed consent to undergo dual-energy x-ray absorptiometry, total body potassium counting bioelectrical impedance analysis, total body water determination, and anthropmetric evaluation.

MAIN OUTCOME MEASURES

Present and compare percentage body fat between HD and PD patients as determined by the methods used.

RESULTS

Percentage fat is not different between HD and PD patients. Differences in absolute values of percent fat between techniques exist.

CONCLUSION

HD patients and PD patients may be evaluated by the methods of body composition used. Percentage body fat will vary among techniques; therefore the same method should be used to follow a patient over time.

Evaluation of plasma osmolality and hormone responses in elderly chronic hemodialysis patients with excessive interdialytic weight gain

Elderly patients may exhibit changes in plasma hormone levels, as well as thirst disorders. Two groups of elderly hemodialysis patients were evaluated to determine if excessive interdialytic weight gain was related to differences in postdialysis plasma osmolality or postdialysis measurement of plasma renin activity, or plasma levels of angiotensin II (a dipsogenic hormone), aldosterone, and vasopressin. Patients mean age was 77.0 +/- 8.8 years and patients were divided into groups, I and II, with less than or greater than 2 kg interdialytic weight gain. Postdialysis plasma osmolality was similar in both groups of patients (309.3 +/- 2.3 vs. 309.6 +/- 2.4 mOsm/Kg, p = 0.8) and postdialysis AVP levels also were no different (2.7 +/- 0.6 vs. 2.1 +/- 0.2 pg/mL, p = 0.3). There was also no statistical difference between postdialysis angiotensin II and aldosterone levels in either group of patients. Plasma renin activity (PRA) was also not different in either group (2.3 +/- 1.1 vs. 0.43 +/- 0.1 ng/mL/hr, p = 0.1), but group I patients, with less than 2 kg weight gain, tended to exhibit higher PRA values perhaps reflecting proximity to their dry weight postdialysis. Since excessive fluid intake did not appear to relate to plasma osmolality and hormone levels studied, it might be suggested that excessive drinking could be due to excessive sodium intake associated with personal dietary habits or perhaps other as yet unmeasured factors.

Comparison of five body-composition methods in peritoneal dialysis patients

Body-composition assessment is an important method of evaluating nutritional status in peritoneal dialysis patients. Because body-composition measurement estimates have not been fully validated in this population, we assessed five body-composition methods in 30 well-dialyzed peritoneal dialysis patients. The techniques studied included bioelectrical impedance analysis, dual-energy X-ray absorptiometry, total-body potassium counting, and anthropometry by two techniques. The dialysis patients were matched for age, race, sex, height, weight, and body mass index with 29 healthy control subjects in our laboratory database. By 5 x 2 x 2 analysis of variance, significant differences were found between results by modality (P < 0.0001) as well as by sex, with women having an increased percentage of fat (P < 0.0001). However, there was no significant intermethod difference by condition (peritoneal dialysis or control). That is, although significantly different percentage fat values were found between the body-composition techniques, this variability was independent of whether the measurement was made on control or peritoneal dialysis patients. Despite the differences between modalities, all techniques were found to correlate significantly with each other (P < 0.01 or better for men and P < 0.001 or better for women). Our experience shows that these routine techniques for measuring body composition can be readily applied to stable peritoneal dialysis patients.

Renal failure: why today's patients live better and longer

The clinical courses of two older patients with progressive renal failure associated with hypertension are described. Their underlying disorders are similar, but there are stark contrasts between medical therapies available now and 50 years ago. Such advances include the development of antihypertensive drugs and antimicrobial medications that have reduced the incidence of renal failure. In addition, recombinant erythropoietin and calcitriol have decreased the morbidity associated with chronic renal failure. Finally, technologic breakthroughs in dialysis have made a once-fatal condition eminently treatable.

Perturbations in sodium balance. Hyponatremia and hypernatremia

Perturbations of serum sodium concentration are the most common electrolyte abnormalities seen in clinical medicine. Patients may exhibit profound alterations in mental status or be asymptomatic. Appropriate diagnosis and treatment is essential to reducing morbidity from serum sodium abnormalities. This article reviews the etiology, symptoms, and treatment of hyponatremic and hypernatremic syndromes.

Sucrose ingestion following exercise: selected cardiovascular, hormonal, renal, and metabolic effects

Carbohydrates, frequently consumed following exercise for glycogen resynthesis, have been shown to have other systemic effects in resting men. We examined the effects of postexercise sucrose (a disaccharide carbohydrate) ingestion on the renal, cardiovascular, and sympathetic nervous systems. Eight men consumed 1 l of water (W) or 1 l of a 200 g sucrose solution (S) following 1 hour of bicycle exercise at 70% heart rate reserve. Measurements were made during 2 hours of recovery. Heart rate and systolic blood pressure were elevated following S as compared to W (p < 0.009, p < 0.04, respectively). Diastolic blood pressure was lower after S (p < 0.04) and mean blood pressure did not differ between beverages. Plasma and urinary catecholamines decreased similarly after exercise regardless of treatment. After S insulin (p = 0.0019) and glucose (p = 0.0036) were increased but serum aldosterone (p = 0.0083) and potassium (p = 0.0285) responses were lower. No differences were observed for plasma renin activity. Urine volume and kaliuresis were less after S (p = 0.03, p = 0.03). A 24% increase in metabolic rate (p = 0.002) and increased respiratory exchange ratio (p = 0.02) after S were observed. Systemic effects of sucrose ingestion following exercise include cardiovascular, renal, endocrine, and metabolic changes.

Assessment of renal osteodystrophy in hemodialysis patients

We performed a prospective study of 30 patients undergoing chronic hemodialysis to determine which of 6 generally available diagnostic procedures provided the most useful information for the assessment of bone disease in hemodialysis patients. The 6 procedures were: routine biochemical measurements, N-terminal parathyroid hormone (N-PTH), radiographic analysis of hands and clavicles, bone density determination by dual photon absorptiometry (DPA), deferoxamine stimulation test, and iliac crest bone biopsy. Serum N-PTH was elevated in 83% of patients but was not significantly associated with abnormalities of other biochemical parameters. No significant relationship was demonstrated between biochemical data and radiographic findings or between biochemical data and bone density by DPA. All patients with abnormal DPA had an elevation of N-PTH; therefore, DPA did not reveal any unsuspected disease. Bone biopsies were done in 20 patients and findings in each were consistent with uremic osteodystrophy, including osteitis fibrosa cystica in 11 patients and aluminum-associated bone disease in 2 patients. Six patients had mixed disease, and 1 patient had osteoporosis. Despite 11 positive deferoxamine tests, bone biopsy revealed aluminum deposition in only 7 of these patients, suggesting extraosseous aluminum accumulation in the remaining 4. Evaluation of the positive and negative predictive accuracies of DPA, x-ray analysis, N-PTH levels, and aluminum bone deposition revealed that normal DPA or x-ray findings do not exclude bone disease, that N-PTH level is a good marker for secondary hyperparathyroidism, and that a negative deferoxamine test excludes aluminum-associated bone disease. Discriminant analysis also reinforced these conclusions.(ABSTRACT TRUNCATED AT 250 WORDS)

Systolic hypertension in the elderly: reasons not to treat

Isolated systolic hypertension in the elderly is associated with increased morbidity and mortality. Accurate measurement of blood pressure in older patients is difficult. Therapy can be associated with various complications, and the special problems of the elderly, such as orthostatic hypotension and hyperkalemia, should be carefully considered. Drugs should be used in low doses and changes in dosage should be made infrequently. Patients should be monitored frequently for untoward effects of therapy. The benefits of blood pressure reduction and the optimal degree of blood pressure reduction remain unknown.

Hyperkalemia in the elderly

Physiologic and pathologic events that occur in patients as they grow older may result in distal renal tubular dysfunction, as well as decreased levels of plasma renin activity and plasma aldosterone. Such alterations result in a tendency toward hyperkalemia. A syndrome termed hyporeninemic hypoaldosteronism, associated with hyperkalemia, has been frequently described in elderly patients. The common occurrence of hyperkalemia in the elderly may be aggravated by the use of drugs that either further suppress renin and/or aldosterone or interfere with distal tubular potassium excretion. Some patients with hyporeninemic hypoaldosteronism respond to diuretic therapy. The recognition of the possible development of severe hyperkalemia in the elderly patient may avoid serious and even fatal complications of this electrolyte disorder.

Frequency of hyponatremia and nonosmolar vasopressin release in the acquired immunodeficiency syndrome

The frequency and pathophysiology of hyponatremia were studied in the acquired immunodeficiency syndrome. Of 71 hospitalized patients surveyed retrospectively, hyponatremia was observed in 37 (52%). Of 48 patients studied prospectively, 27 (56%) were hyponatremic. In 16 hyponatremic patients, volume status; serum and urine osmolalities; renal, adrenal, and thyroid function; and plasma vasopressin levels were assessed. Urine osmolalities were inappropriately elevated (mean, 377 mmol/kg of water) relative to serum osmolalities (mean, 268 mmol/kg of water). Four patients had moderate renal insufficiency. Plasma vasopressin levels were elevated in 15 patients, with the highest levels seen in patients who died (median, 7.08 pmol/L). Hyponatremia of multiple etiologies occurred in a majority of inpatients with the acquired immunodeficiency syndrome, often following the administration of hypotonic fluids, and was associated with a 30% (8/27) short-term mortality.

Increased levels of plasma renin, aldosterone, catecholamines and vasopressin in chronic ambulatory peritoneal dialysis (CAPD) patients

Fluid excess can cause hyporeninemia and hypoaldosteronemia in hemodialysis patients. In six patients on CAPD, plasma renin activity (PRA) and plasma aldosterone (PA) were elevated to levels of : PRA 10.2 +/- 2.9 nl (1-5 ng/ml/h), and PA: 47.4 +/- 16.2 (normal 5-20 ng/dl). In 4 patients, data posthemodialysis and later during CAPD revealed that PRA increased from 0.9 +/- 0.3 to 14.1 +/- 4.6 and PA increased from 3.4 +/- 0.3 to 67.4 +/- 24.9 on CAPD (p less than 0.05). Mean arterial pressure was lower on CAPD and serum glucose was higher. No significant difference was seen in weight, hematocrit, BUN, or potassium, however. Plasma volume was not decreased in five CAPD patients: 3619 +/- 358 ml (predicted 3083 +/- 201 ml). Elevated catecholamine levels were seen in CAPD patients: norepinephrine 868.0 +/- 104.1 (normal 358.4 +/- 41.5 pg/ml), epinephrine 386.3 +/- 49.2 (normal 58.3 +/- 10.6 pg/ml). Plasma vasopressin levels were elevated to the range usually seen with hyperosmolality. In eight patients who lost or gained weight on CAPD, levels of PRA and PA changed as expected, but catecholamine levels did not correlate with weight changes. The data suggest that in CAPD patients, PRA and PA may be elevated in association with augmented sympathetic stimulation and elevated vasopressin levels. Serial observations demonstrated that PRA and PA can respond appropriately to changes in body weight, while catecholamine and vasopressin levels seem to be influenced by other factors.

The renin-angiotensin system is not responsible for hypertension following coronary artery bypass grafting

Systemic hypertension following coronary artery bypass graft (CABG) procedures has been reported to occur in 15% to 80% of cases. Previous reports have implicated the renin-angiotensin system as being responsible, at least in part, for this phenomenon. In this prospective study, 18 previously normotensive subjects were studied before, during, and after CABG. In 4 patients (22%), paroxysmal postoperative hypertension developed (systolic blood pressure greater than 150 mm Hg). There were no differences between the normotensive and hypertensive groups in plasma renin activity, angiotensin II level, or aldosterone level. Despite the trend toward elevation of these variables during cardiopulmonary bypass (CPB), all had returned to control levels within two hours after CPB, whether or not hypertension developed. Serum norepinephrine levels were elevated (.10 greater than p greater than .05) in the hypertensive group at the time hypertension developed. No other relationship or pattern could be defined to distinguish the hypertensive from the normotensive group. The renin-angiotensin system does not appear to be responsible for paroxysmal hypertension following CABG.

Renal disease in patients with AIDS: a clinicopathologic study

To determine the nature and frequency of renal disorders in AIDS we reviewed the records of thirty-two patients hospitalized over a twenty-two month period. Group I, including all patients with AIDS who demonstrated proteinuria and/or renal insufficiency, numbered thirteen patients, in ten of whom renal tissue was available. Renal abnormalities included proteinuria in twelve patients, which exceeded two grams per day in seven. The glomerular histologic lesions included focal glomerulosclerosis, diffuse mesangial hypercellularity, diffuse proliferative glomerulonephritis, and membranoproliferative glomerulonephritis. The nonglomerular histologic lesions included acute tubular necrosis, nephrocalcinosis, focal interstitial nephritis, and one case each of intrarenal cryptococcal infection and renal cell carcinoma. Nine of these thirteen patients developed renal insufficiency, and four of them required dialysis. Their mortality by the end of the study period was eleven of thirteen patients (85 percent), significantly worse in the short term than AIDS patients without renal problems. The patients in Group I were compared to the nineteen AIDS patients without renal abnormalities in Group II. The Group I patients had a higher incidence of oral and esophageal candidiasis, other fungal infections, and infections with Mycobacterium avium-intracellulare. They also had a higher incidence of exposure to aminoglycoside antibiotics and amphotericin B, and experienced more clinical shock than their Group II counterparts. It is concluded that patients with AIDS may demonstrate renal abnormalities on the basis of immune, hemodynamic, infectious, and neoplastic derangements.

Plasma osmolality, volume, and renin activity at the "anaerobic threshold"

Plasma renin activity (PRA), volume (PV), osmolality, and hemodynamic parameters were examined in relation to the anaerobic threshold (AT) during progressive cycle ergometry (PE) and repetitive bouts of unilateral isokinetic knee extension-flexion (LE) at 50% maximum voluntary contractions in eight normotensive males. During PE, the observed rise in PRA paralleled that of lactate with abrupt increases occurring at the AT. Correlation of % delta lactate (La), % delta osmolality, and % delta PV with % delta PRA were r = 0.65, 0.36, and -0.51, respectively (all P less than 0.01). In addition, when mean arterial pressure was plotted as a function of VO2, the rate of rise was greater below the AT than above the AT (11.5 vs. -2.4 mmHg X l-1 X min, P less than 0.001). A time control study (TC) exercising subjects for the same duration but at work rates maintained below the AT resulted in significantly lower values for both PRA and La (7.18 vs. 11.27 mg angiotensin I (ANG I) X ml-1 X min and 3.16 vs. 9.93 mM, P less than 0.05 for TC vs. PE) while producing a similar fall in % delta PV and rise in osmolality. During LE, a high correlation was obtained for % delta PRA and % delta La (r = 0.86, P less than 0.01) but not for % delta PRA with % delta PV or % delta osmolality. The data demonstrate that PRA parallels lactate during exercise and that mean arterial pressure rises more slowly beyond the AT despite a more rapid rise in PRA.

Long-duration submaximal exercise conditioning in hemodialysis patients

Objective changes in exercise tolerance were evaluated in five chronic hemodialysis patients (HD) following a ten week aerobic treadmill exercise conditioning program designed to exercise patients at a level approximating their anaerobic threshold (AT). This exercise conditioning program resulted in a 21% increase in peak oxygen consumption, an increase in test duration from 17.40 +/- 1.26 to 22.60 +/- 0.87 min (P less than 0.025), and an increase in AT from 0.81 +/- 0.08 to 0.97 +/- 0.08 1/min (P less than 0.05). These physiologic changes in exercise tolerance resulted in an overall increase in work capacity permitting the HD patient to perform a larger portion of the imposed work load aerobically.

Management of acute cardiac tamponade by subxiphoid pericardiotomy

Eighteen patients with cardiac tamponade were treated by subxiphoid pericardiotomy performed with the patients under local anesthesia. This group included 9 cases of uremic pericarditis (50%), 5 cases of metastatic cancer (28%), 2 cases of trauma (11%), 1 case of tuberculosis (5.5%), and 1 case of unknown cause. Immediate relief from acute cardiac tamponade was obtained in all 18 cases with only minor and self-limiting postoperative complications, including transient supraventricular arrhythmias (five cases) and fever (five cases). There were no deaths related to either the operative procedure or reaccumulation of the pericardial effusion. The drainage period averaged 9.6 days (range, three to 28 days). Pericardial biopsy was performed in 15 of 18 cases. We conclude that subxiphoid pericardiotomy is a safe and effective method for the management of pericardial effusion of diverse causes. The ability to perform this technique safely using local anesthesia and the capacity to obtain a biopsy specimen under direct visualization make this technique superior to both needle pericardiocentesis and pericardiectomy in the acutely ill patient.

Idiopathic retroperitoneal fibrosis: a systemic connective tissue disease?

Renal histology of a patient with idiopathic retroperitoneal fibrosis demonstrated a proliferative crescentic glomerulonephritis with intramembranous electron-dense deposits. These findings were interpreted as being consistent with an immune complex glomerulonephritis. Serologic studies revealed a positive antismooth muscle antibody titer of 1:80 and a weakly positive antinuclear antibody titer of 1:40. No distinct systemic disease was identified. While fibrosis of the retroperitoneum can occur in association with a number of distinct pathologic conditions and pharmacologic agents, the mechanism responsible for the development of the idiopathic variety of retroperitoneal fibrosis remains unclear. Our observation of an immune complex glomerulonephritis and the cumulative data on idiopathic retroperitoneal fibrosis are consistent with the concept that the fibrosis may be a local expression of an immunologically mediated systemic disease.

Carbamazepine-induced syndrome of inappropriate antidiuretic hormone secretion. Reversal by concomitant phenytoin therapy

The syndrome of inappropriate antidiuretic hormone secretion, with marked hyponatremia, was observed in an elderly women who was taking carbamazepine for trigeminal neuralgia. Subsequent studies revealed this effect to be directly related to the administration of the drug. Substantial water retention has not been previously described in patients taking normal volumes of fluid and taking standard doses of carbamazepine. Additionally, it was determined that the antidiuretic effect of carbamazepine could be blocked by phenytoin. The actions of both drugs on renal water excretion, and the interactions of the drugs were observed to be dose-related.

Severe sodium depletion syndrome during lithium carbonate therapy

Lithium carbonate, useful in the treatment of manic-depressive disorders, can produce nephrogenic diabetes insipidus. The drug, therefore, has been used to facilitate renal waster excretion when severe hyponatremia occurs in the syndrome of inappropriate antidiuretic hormone secretion. Symptomatic dilutional hyponatremia developed in a patient with pulmonary carcinoma whom we treated. Lithium carbonate was administered and renal sodium wasting, hypovolemia, and hypotension occurred. Hyperkalemia was also observed, and since adrenal steroid levels were not decreased, impairment of distal tubular function was suggested. Lithium carbonate blocks antidiuretic hormone effect by decreasing collecting duct cyclic adenosine monophosphate generation. These observations suggest that more generalized inhibitory effects on renal tubular function may also result from its use. An alternative drug, demeclocycline, may be preferable.

"Bicarbonate resistant" metabolic acidosis in association with ethylene glycol intoxication

A case of massive ingestion of ethylene glycol is described. The clinical characteristics of this disorder such as persistent metabolic acidosis and oxaluria as well as changes in serum osmolality that may accompany ingestion of certain toxins are emphasized. The rapid clearance of ethylene glycol from the blood during hemodialysis is noted and the use of ethyl alcohol to block metabolic conversion of ethylene glycol to oxalic acid, which is also a toxin, is described. The importance of early diagnosis and therapy is stressed.

Parathyroid hormone responsiveness in hypoparathyroidism with hypomagnesemia

The failure to respond normally to parathyroid hormone (PTH) administration has been reported in patients with severe hypomagnesemia. A patient with hypoparathyroidism and a markedly decreased serum concentration of magnesium (0.7 mEq/liter), but a normal red blood cell magnesium level, is described who increased serum calcium concentration and decreased per cent renal tubular reabsorption of phosphate when parathyroid extract was given. It is suggested that PTH responsiveness in hypomagnesemic patients may, at least in part, be dependent upon the adequacy of intracellular magnesium stores. This interpretation is supported by the normal cellular (red blood cell) magnesium concentrations observed in this patient and in comparable studies in which PTH responsiveness in the presence of hypomagnesemia was demonstrated. In addition, a failure of optimal renal conservation of magnesium was noted to occur in this patient since, despite hypomagnesemia, urinary magnesium excretion was greater than the 1 mEq/day loss that is seen when magnesium conservation is induced by means such as dietary restriction.

Anion excretion pattern following infusion of hyperoncotic human serum albumin into dogs

The effects of hyperoncotic human serum albumin on the excretion rates of several electrolytes and cyclic-AMP were measured in mongrel dogs and the results were compared with those obtained after the infusion of saline. Hyperoncotic albumin increased the excretion rates of sodium, potassium, bicarbonate, and phosphate. There was a small increase in chloride excretion after albumin, while there was a significant decrease in the rate of excretion of cyclic-AMP. Saline, on the other hand, caused a marked increase in the rate of of excretion of all the measured ions. Like albumin, saline was associated with a decrease in the rate of excretion of cyclic-AMP. The marked increase in bicarbonate and phosphate excretion suggests that the response to albumin which includes decreased isotonic reabsorption in the proximal tubule and increased urinary sodium excretion could result from decreased reabsorption in the proximal tubule accompanied by distal sodium and chloride reabsorption. Saline, on the other hand, caused a greater increase in sodium excretion and, although phosphate and bicarbonate excretion also increased, a much greater effect on the excretion of chloride was observed, suggesting that saline may also decrease sodium and chloride reabsorption in the distal nephron.