Donald R. Mars

Effect of aerobic exercise training on patients with systemic arterial hypertension

One hundred five patients with established diastolic hypertension were enrolled in an exercise program to examine the effect of aerobic conditioning on blood pressure. In four patients, the decrease in mean blood pressure was less than 5 mm Hg; in all others, there was a significant decline in arterial blood pressure. In 58 patients who were not taking drug medication in the pre-exercise period, mean blood pressure decreased by 15 mm Hg. Of 47 patients receiving drug therapy during the pre-exercise period, 24 were able to discontinue all medication. Mean blood pressure in this group fell from 116.9 +/- 6.5 mm Hg to 97.2 +/- 9.2 mm Hg as a result of exercise. In patients still taking antihypertensive drugs, mean pressure decreased from 120.9 +/- 28.8 mm Hg to 104.4 +/- 17.9 mm Hg after three months of exercise. It is concluded that in patients physically and emotionally able to exercise, a significant decline in blood pressure can be achieved.

Prevention of Recurrent Urinary Tract Infections in Postmenopausal Women

Twelve postmenopausal women who experienced frequent urinary tract infections were found to have atrophic vaginitis. Four of them who were taking sulfonamide preparations chronically also had an interstitial nephritis manifest by decreasing glomerular filtration rate and eosinophiluria. Treatment consisted of a Betadine douche daily for 1 week, administration of an appropriate nonsulfonamide antibiotic, and institution of estrogen therapy to restore glycogen deposition in the vaginal epithelium and promote return of a normal vaginal pH and bacterial flora. Prior to estrogen therapy, the frequency of infection was four per patient per year. During a follow-up observation period ranging from 2 to 8 years, there have been only four infections in the entire group. When sulfonamides were discontinued in the 4 patients with manifestations of interstitial nephritis, the eosinophiluria cleared, and the glomerular filtration rate increased significantly.

Effects of phosphate loading on 2,3-diphosphoglycerate and maximal oxygen uptake.

Increased concentration of red blood cell 2,3-diphosphoglycerate (RBC 2,3-DPG) shifts the hemoglobin-oxygen dissociation curve to the right, thus theoretically allowing better oxygenation of tissues. To determine whether such a shift is physiologically significant, we investigated the effects of oral phosphate loading on several parameters including plasma phosphate concentration, RBC 2,3-DPG, hematocrit and hemoglobin concentration, maximal oxygen uptake (VO2max), and degree of lactic acidemia in 10 well-trained distance runners. After control determinations were made, either a phosphate load or a placebo was given for 3 d before the athlete was restudied. A placebo and two phosphate-loading studies were performed at weekly intervals, followed by 2 wk of rest and another post-intervention control study. Blood samples for control values were drawn before and after a standard warm-up period, after treadmill exercise at a 10% grade, and at the completion of the VO2 determination. After oral phosphate loading there was a significant increase in serum phosphate and RBC 2,3-DPG. Maximal oxygen uptake was significantly increased and correlated with the rise in RBC 2,3-DPG (r = 0.81). The increase in blood lactate after exercise on the 10% grade was attenuated during sessions which followed phosphate loading.

Hepatorenal syndrome. Studies of the effect of vascular volume and intraperitoneal pressure on renal and hepatic function

Eleven patients with well-documented hepatorenal syndrome were studied by measurement of blood volume, glomerular filtration rate, renal plasma flow, plasma aldosterone concentration, renin substrate concentration, and plasma renin activity. They were then given 750 ml of stored plasma, 750 ml of fresh frozen plasma, and then an infusion of angiotensin II, in random order on successive days. Infusion of fresh frozen plasma improved function more than did stored plasma and in addition returned a very low filtration fraction toward normal. Angiotensin II infusion increased filtration fraction, but decreased glomerular filtration rate, renal plasma flow, and urine flow sharply. Patients were then given a daily infusion of 1,000 ml of fresh frozen plasma for seven to 18 days to expand the blood volume to supranormal levels as assayed by serial measurement of blood volume. Plasma aldosterone levels decreased to a normal range, glomerular filtration rate and renal plasma flow both increased, and urinary excretion of sodium and potassium both returned toward normal. The effect of intraperitoneal pressure was then studied by measuring glomerular filtration rate, renal plasma flow, pressure in the vena cava, hepatic vein free flow, and hepatic vein wedged pressure before, during, and after paracentesis to reduce the intraperitoneal pressure from 30 to 40 cm H2O to 12 to 17 cm H2O. Venous pressures moved parallel to ascitic fluid pressures, and glomerular filtration rate, renal plasma flow, and urine flow all improved sharply; then, as ascitic fluid continued to form, reducing vascular volume, urine flow, glomerular filtration rate, and renal plasma flow all decreased slowly. Six patients then underwent placement of a LeVeen shunt. Improvement in glomerular filtration rate and renal plasma flow and clinical condition was dramatic. During postoperative observation of up to two years, progressive improvement in hepatic function has occurred.

Laparoscopically Assisted Percutaneous Renal Biopsy

We performed laparoscopically assisted percutaneous renal biopsy on 4 patients with azotemia or renal dysfunction who were believed to be unsuitable candidates for percutaneous renal biopsy. Tissue adequate for diagnosis was obtained in all 4 cases. Complications included subcutaneous emphysema in 1 patient and a small splenic capsular tear in 1, which was managed laparoscopically and did not require transfusion. Bleeding from the renal biopsy occurred in 1 patient and was easily managed laparoscopically. We recommend laparoscopically assisted percutaneous renal biopsy as an alternative method of renal biopsy in patients who can tolerate general anesthesia and who are not candidates for percutaneous renal biopsy.

Iodine Retention and Thyroid Dysfunction in Patients on Hemodialysis and Continuous Ambulatory Peritoneal Dialysis

Povidone-iodine is frequently used as an antiseptic in patients on chronic dialysis. In order to determine if the use of povidone-iodine affects thyroid function in these patients, we measured serum iodine and thyroid hormone levels in dialysis patients prior to and following discontinuation of topical povidone-iodine antiseptics. Serum inorganic iodine levels were elevated initially in nearly 90% of the patients (19 on hemodialysis, 12 on continuous ambulatory peritoneal dialysis [CAPD]). Following discontinuation of povidone-iodine, iodine levels over a 3-month period decreased modestly in patients on CAPD (n = 5) and were unchanged in patients on hemodialysis (n = 5). Total and free thyroxine levels were frequently low but did not correlate with protein-bound or inorganic iodine levels and did not change after discontinuation of povidone-iodine. Thyrotropin levels correlated significantly (r = .62, P less than .01) with inorganic iodine levels in patients on hemodialysis, but not for patients on CAPD. We conclude that abnormal thyroid function tests are common in dialysis patients but are not related to iodine retention or to the routine use of topical povidone-iodine-containing antiseptics.

Marathon running: physiological and chemical changes accompanying late-race functional deterioration

SummaryTwenty-one experienced runners were studied before, during and immediately after a marathon race to ascertain whether either depletion of energy substrate or rise in body temperature, or both, contribute to laterace slowing of running pace. Seven runners drank a glucose/electrolyte (GE) solution ad libitum (Na− 21 mmol 1−1, K+ 2.5 mmol l−1, Cl− 17 mmol l − l, PO42− 6 mmol 1−1, glucose 28 mmol 1−1) throughout the race; 6 drank water and 8 drank the GE solution diluted 1:1 with water. Although average running speeds for the three groups were not significantly different during the first two-thirds (29 km) of the race, rectal temperature was significantly higher (P < 0.05) and reduction of plasma volume was greater (P <0.05) in runners who replaced sweat losses with water. During the last one-third of the race, the average running pace of the water-replacement group slowed by 37.2%; the pace slowed by 27.9% in the 8 runners who replaced their sweat loss with GE diluted 1:1 with water (1/2 GE) and 18.2% in runners who replaced fluid loss with full-strength solution (GE). Eleven runners (5 in the water group, 4 in the 1/2 GE group and 2 in the GE group) lapsed into a walk/run/walk pace during the last 6 miles of the race. Ten of these had a rectal temperature of 39° C or greater after 29 km of running, and plasma volume in these runners was reduced by more than 10%. Only 1 runner among those who ran steadily throughout the race had such an elevation of temperature and reduction of plasma volume. A significant reduction in plasma glucose concentration (less than 3.3 mmol 1−1) was present in 5 of the 11 walk/run/walk subjects and in none of those who ran steadily. The results are consistent with the suggestion that assumption of the walk/run/walk pace resulted from high body temperature associated with either diminished plasma volume or low blood sugar.

Severe hypernatremia complicating urinary tract obstruction

Severe hypernatremia and hyperosmolar dehydration developed in a patient with partial urinary tract obstruction. The urine was initially hypotonic, and there was no response to exogenous vasopressin. These abnormalities resolved with relief of the urinary tract obstruction and replacement of the water deficit. This case documents lower urinary tract obstruction as a cause of nephrogenic diabetes insipidus and severe hypernatremia and illustrates its reversible nature.

Marked azotemia and increase in serum creatinine: case report of an unusual feature of acute ureteral obstruction in a renal allograft recipient.

A patient is described who presented with late ureteral necrosis following renal transplantation, a complication that usually is seen in the early perioperative period. The patient was anuric with azotemia and a high serum creatinine. Response to surgical correction of ureteral obstruction was excellent and renal function returned to normal within 6 days postoperatively.