Biomedical subjects
J C Ayus
Publications and source records attributed to J C Ayus.
Role of hemodynamic changes in the increased cation excretion after acute unilateral nephrectomy in the anesthetized dog.
Studies were carried out in anesthetized dogs to characterize the increase in cation excretion which occurs after acute unilateral nephrectomy (AUN). 60 min after AUN, cation excretion had increased from 31.5+/-2.7 to 66.3+/-12.0 mueq/min (P < 0.005) and fractional cation excretion had increased from 0.56+/-0.05 to 1.03+/-0.14% (P < 0.005), as the glomerular filtration rate was unchanged and renal blood flow fell. The increased cation excretion was accompanied by an increase in fractional phosphate excretion, no change in chloride excretion, and a fall in renin secretion. These alterations in renal function were associated with marked changes in systemic hemodynamics: cardiac output fell from 2.52+/-0.24 to 1.85+/-0.16 liters/min (P < 0.001), as diastolic pressure rose without an overall increase in mean arterial pressure, and heart rate fell. To assess the importance of these hemodynamic changes in the renal response, AUN in a separate group of dogs was accompanied by the simultaneous opening of a surgically created femoral artery-to-vein fistula at flow matching the blood flow to the removed kidney. When this was done, no alterations in systemic or renal hemodynamics were observed, and cation excretion did not differ from control. Subsequent closure of the fistula then caused a fall in cardiac output from 2.15+/-0.25 to 1.77+/-0.20 liters/min (P < 0.05), and an increase in cation excretion from 34.6+/-9.5 to 52.3+/-13.7 mueq/min (P < 0.01), thus mimicking the findings with AUN alone.These results demonstrate that AUN causes hemodynamic changes resembling those seen on closure of a chronic arteriovenous fistula. Prevention of these hemodynamic changes after AUN also prevents the functional adjustment of the remaining kidney, suggesting that they may be important in initiating the renal response. The increased electrolyte excretion after AUN may occur through mechanisms similar to that seen on closure of an arteriovenous fistula.
Rhabdomyolysis and acute myoglobinuric renal failure. Complications of inferior vena cava ligation.
A 50-year-old man underwent inferior vena cava ligation because of repeated pulmonary emboli despite adequate heparin therapy. His immediate postoperative course was complicated by the development of massive edema in the lower extremities, leading to a compromised arterial blood flow with the resulting ischemic myopathy and acute myoglobinuric renal failrue. Although massive pooling of body fluids in the lower extremities with fatal consequences has been reported as an immediate complication of the sudden mechanical obstruction of the venous return, to our knowledge this is the first case of myoglobinuric acute renal failure due to rhabdomyolysis reported in association with inferior vena cava ligation.
Chronic hyponatremic encephalopathy in postmenopausal women: association of therapies with morbidity and mortality.
CONTEXT: Chronic hyponatremia in postmenopausal women is a common clinical problem often viewed as benign. Fluid restriction is usually the recommended therapy, largely because the extent of morbidity is unknown and because it has been postulated that intravenous (IV) sodium chloride may cause brain damage. OBJECTIVE: To compare IV sodium chloride with fluid restriction in the treatment of postmenopausal women with chronic symptomatic hyponatremia. DESIGN: Nonrandomized prospective study. SETTING: Two university medical centers and affiliated community hospitals. PATIENTS: A total of 53 postmenopausal women with chronic symptomatic hyponatremia (chronic plasma sodium <130 mmol/L in the presence of central nervous system manifestations) treated consecutively from 1988-1997 and followed up for 1 year. The mean (SD) age of the patients was 62 (11) years. INTERVENTIONS: The therapeutic interventions were IV sodium chloride before respiratory insufficiency (n = 17), IV sodium chloride after respiratory insufficiency (n = 22), and fluid restriction only (n = 14). MAIN OUTCOME MEASURES: Morbidity and neurological outcome at 4 months or longer as assessed by cerebral performance category (CPC) in relation to the therapy, initial plasma sodium level, and rate of correction. RESULTS: Chronic symptomatic hyponatremia (mean [SD] sodium level 111 [12] mmol/L) was present for 5.2 [4.5] days. Death or major morbidity occurred in 44 (83%) of 53 patients, including 10 with orthopedic injury. Twelve patients had hypoxemia (PO2 = 63 [25] mm Hg) and cerebral edema. Among patients who received IV sodium chloride before respiratory insufficiency, plasma sodium levels were increased by 22 (10) mmol/L in 35 hours and patients had a CPC of 1.0 (normal or slight disability). Among patients who received IV sodium chloride after respiratory insufficiency, plasma sodium levels were increased by 30 (6) mmol/L in 41 hours and patients had a CPC of 3.0 (1.2) (severe disability). Among patients who had fluid restriction only, plasma sodium levels were increased by 3 (2) mmol/L in 41 hours and patients had a CPC of 4.6 (0.7) (4 = persistent vegetative state; 5 = death). The outcomes did not correlate with either the initial plasma sodium level (r=0.05, P>.12) or the rate of correction (r=0.31, P>.10). CONCLUSIONS: Chronic symptomatic hyponatremia in postmenopausal women can be associated with major morbidity and mortality. Therapy with IV sodium chloride was associated with significantly better outcomes than fluid restriction.
Clotted arteriovenous grafts: a silent source of infection.
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