Mechanism of exercise-induced ocular hypotension.
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PURPOSE: Although acute dynamic exercise reduces intraocular pressure (IOP), the factors that provoke this response remain ill-defined. To determine whether changes in colloid osmotic pressure (COP) cause the IOP changes during exercise, standardized exercise was performed after dehydration and hydration with isosmotic fluid. METHODS: Progressive cycle ergometer exercise to volitional exhaustion was performed after 4 hours' dehydration, and after hydration with 946 ml isosmotic liquid (345 mOsM). In each experiment, venous blood taken before and immediately after exercise was analyzed for hematocrit, plasma protein concentration, total plasma osmolality, and plasma COP. RESULTS: Exercise in both experiments significantly reduced IOP and elevated COP (each P < 0.01). Dehydration, compared with hydration, also significantly reduced IOP and elevated COP, when measured before and after exercise (P < 0.05). The correlation of mean IOP with mean COP, over the entire range created by varying exercise and hydration statuses, was statistically significant (r = -0.99; P < 0.001). In contrast, other indexes of hydration status, including hematocrit, total plasma osmolality, and plasma protein concentration, failed to change as IOP changed and failed to correlate with IOP, on either a group or individual basis, in conditions of varying levels of exercise and hydration. CONCLUSIONS: Acute dynamic exercise and isosmotic fluid ingestion each seem to change IOP through changes in COP. (+info)
Comparison of Payne and Scott operations for morbid obesity.
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One hundred five patients were operated upon for morbid obesity using accepted criteria for operation. Forty-five patients with the Payne operation (35 cm of jejunum anastomosed end-to-side to 10 cm of ileum) were compared with 45 patients having the Scott operation (30 cm of jejunum anatomosed end-to-end to 15 cm of ileum with the proximal cut end of ileum vented into the transverse colon). The weight loss in the first two years was similar, although the Scott procedure patients lost slightly more weight. Comparison of the two groups by a new grading system also showed little difference in the two procedures. The Scott procedure takes longer and subjects the patient to an additional anastomosis. Study of a smaller group of patients having the Scott operation with varying lengths of jejunum and ileum indicates that there should not be less than 30 cm of jejunum nor more than 15 cm of ileum left in continuity. The length of jejunum is particularly important in the production of weight loss, and accurate intraoperative measurement of intestinal length is crucial. In the postoperative period the length of functional jejunum and ileum can be determined by upper gastrointestinal barium roentgenograms. (+info)
Hypertonic saline test for the investigation of posterior pituitary function.
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The hypertonic saline test is a useful technique for distinguishing partial diabetes insipidus from psychogenic polydipsia, and for the diagnosis of complex disorders of osmoreceptor and posterior pituitary function. However, there is little information concerning its use in childhood. The experience of using this test in five children (11 months to 18 years) who presented diagnostic problems is reported. In two patients, in whom water deprivation tests were equivocal or impractical, an inappropriately low antidiuretic hormone (ADH) concentration (< 1 pmol/l) was demonstrated in the presence of an adequate osmotic stimulus (plasma osmolality > 295 mosmol/kg). In two children--one presenting with adipsic hypernatraemia and the other with hyponatraemia complicating desmopressin treatment of partial diabetes insipidus--defects of osmoreceptor function were identified. Confirming a diagnosis of idiopathic syndrome of inappropriate ADH secretion (SIADH) was possible in a patient with no other evidence of pituitary dysfunction. The hypertonic saline test was well tolerated, easy to perform, and diagnostic in all cases. (+info)
Characterization of subtypes of hypertension in CAPD patients by cyclic guanosine monophosphate.
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OBJECTIVE: While most hypertensive patients with end-stage renal disease normalize high blood pressure with fluid removal by continuous ambulatory peritoneal dialysis (CAPD), there is a significant proportion of CAPD patients whose blood pressure can be controlled only by antihypertensive drugs. METHOD AND PATIENTS: To study the hypothesis that such patients are still volume overloaded, we used plasma cyclic guanosine monophosphate (cGMP) as a marker for hydration status. Thirty-two CAPD patients were divided into 3 groups: group 1, normotensive patients (n = 12); group 2, hypertensive patients who normalized their blood pressure with fluid removal (n = 12); group 3, hypertensive patients whose blood pressure was refractory to intensified fluid removal (n = 8). RESULTS: Mean cGMP levels were significantly higher in dialysis-sensitive hypertension (27 +/- 5 pmol/mL) than in dialysis-refractory hypertension (15 +/- 2 pmol/mL), or in normotensive patients (13 +/- 4 pmol/mL). Reduction of excess fluid in volume overloaded hypertensive CAPD patients resulted in a normalization of cGMP levels (14 +/- 8 pmol/mL), but did not affect this volume marker in patients with dialysis-resistant hypertension (10 +/- 4 pmol/mL). CONCLUSION: Plasma cGMP levels are elevated in volume overload-induced hypertension complicating CAPD. Hypertensive CAPD patients whose plasma cGMP levels are within normal limits have raised blood pressure refractory to volume removal. Our findings are consistent with the hypothesis that inadequate removal of excess volume plays a major role in a subset of patients with CAPD hypertension. (+info)
Hyponatremia in the rat in the absence of positive water balance.
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The purpose of this report is to determine the mechanisms that lead to hyponatremia when isotonic saline was the only fluid infused into rats given antidiuretic hormone (ADH), and what might minimize the degree of this hyponatremia. Normal rats were deprived of food and water for the 24-hr study period. They received an infusion of isotonic saline to expand their extracellular fluid (ECF) volume with and without exogenous ADH administration (N = 8 in each of the four groups). Similar studies were also carried out in 32 rats fed a low electrolyte diet for 72 hr before the experiment. An additional control group was fed the low electrolyte diet supplemented with sodium (Na), potassium (K), and chloride (Cl). Hyponatremia developed over 24 hr in rats fed their usual diet if treated with ADH and isotonic saline (fall, 13 +/- 2 mM, P < 0.01). The hyponatremia was caused by negative balance for Na + K salts. Hyponatremia did not develop after the saline + ADH treatment if rats were pretreated for 3 days with a low electrolyte diet. Two factors were required to develop this hyponatremia--generation of electrolyte-free water as a result of the excretion of a large quantity of Na + K salts at a high concentration in the urine, and prevention of the excretion of this electrolyte-free water by ADH. Increasing the avidity for Na reabsorption by the kidney prevented this type of hyponatremia from developing. (+info)
Management of the hyperosmolar hyperglycemic syndrome.
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Hyperglycemic hyperosmolarity is part of a clinical spectrum of severe hyperglycemic disorders ranging from pure hyperglycemic hyperosmolarity without ketosis to diabetic ketoacidosis, with significant overlap in the middle. From 50 to 75 percent of hospitalizable patients who have uncontrolled diabetes present with significant hyperosmolarity. An altered state of consciousness attributable to uncontrolled diabetes is virtually always the result of severe hyperosmolar hyperglycemia. The linchpin of therapy is prompt, rapid administration of crystalloid solutions that have tonicity appropriate to the level of hyperosmolarity. A decrease in the plasma glucose concentration indicates the adequacy of therapy, especially rehydration; the goal is for the plasma glucose level to decline by at least 75 to 100 mg per dL (4.2 to 5.6 mmol per L) per hour. Patients with hyperosmolar hyperglycemic syndrome are often chronically ill, and they may have major total body deficits of potassium, phosphate and magnesium, as well as B-complex vitamins (especially thiamine). These deficits also require attention and correction during therapy. (+info)
Electrolyte disorders following massive insulin overdose in a patient with type 2 diabetes.
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We present a case of a 47-year-old man with Type 2 diabetes mellitus who attempted suicide with 2,100 U of insulin injected subcutaneously. Administration of dextrose intravenously was required to maintain the blood glucose concentration normally for 5 days. Moreover, hypokalemia, hypophosphatemia, and hypomagnesemia were also seen for 24 hours after insulin injection. The serum phosphorus and magnesium concentrations decreased to nadirs of 1.6 mg/dl and 1.6 mg/dl respectively 7 hours after insulin injection. Electrolyte disorders other than hypokalemia may be induced in hypoglycemic patients by massive insulin overdose. (+info)
Risk factors for peripartum and postpartum stroke and intracranial venous thrombosis.
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BACKGROUND AND PURPOSE: The study goal was to identify potential risk factors for peripartum or postpartum stroke and intracranial venous thrombosis. METHODS: Data from the Healthcare Cost and Utilization Project were analyzed for the years 1993 and 1994. Observed values were weighted with poststratification discharge weights to project to the universe of all discharges from community hospitals located in the United States. Nationally representative estimates of risk were calculated on the basis of age, race, mode of delivery, income, third-party payer, hospital size, hospital ownership, hospital location (rural versus urban), hospital teaching status, census region, and presence of specific complications. Multivariate models were developed with the use of logistic regression. RESULTS: Among 1 408 015 sampled deliveries, there were 183 observed cases of peripartum stroke and 170 cases of peripartum intracranial venous thrombosis in 17 states in the United States in 1993 and 1994. There were an estimated 975 cases of stroke and 864 cases of intracranial venous thrombosis during pregnancy and the puerperium in the United States among 7 463 712 deliveries during 1993 and 1994, for estimated risks of 13.1 cases of peripartum stroke and 11.6 cases of peripartum intracranial venous thrombosis per 100 000 deliveries. Multivariate analysis showed that the following were strongly and significantly associated with both peripartum and postpartum stroke: cesarean delivery; fluid, electrolyte, and acid-base disorders; and hypertension. Covariates that were strongly and significantly associated with both peripartum and postpartum intracranial venous thrombosis included cesarean delivery, hypertension, and infections other than pneumonia and influenza. CONCLUSIONS: Pregnancy-related hypertension and cesarean delivery are important risk factors for both stroke or intracranial venous thrombosis. (+info)