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Biomedical subjects

F Manfredi

Publications and source records attributed to F Manfredi.

At least 55 records · Page 3Linked to original sources
PubMed1982

Abnormalities of sodium and H2O handling in chronic obstructive lung disease.

The pathogenesis of edema and hyponatremia in chronic obstructive lung disease (COLD), is poorly understood. Previously, in nonedematous patients with hypercapnia, small increases in plasma renin activity occurred, which prompted this study. In 25 hypercapnic, edematous, often hyponatremic patients with COLD, we measured renal hemodynamics, H2O, and sodium (Na+) excretion, plasma levels of renin activity (PRA), plasma levels of aldosterone (PA), and the plasma arginine vasopressin (AVP)-osmolality relationship. A high prevalence of elevated PRA, PA, and AVP levels excessively high for plasma osmolality was observed. Elevated PRA and Pa correlated with the inability to excrete Na+; an elevated AVP level correlated with the inability to excrete H2). These data suggest that, in conjunction with the hypercapnia-hypoxia-mediated disturbance in renal function, stimulation of the renin-aldosterone level and of the AVP systems contributes, respectively, to edema formation and to hyponatremia in advanced COLD.

Aldosterone↗
PubMed1979

Steroids, hypoxemia, and oxygen transport.

This study investigated the effects of administration of methylprednisolone on oxygen transport in ten stable hypoxemic (mean arterial oxygen pressure, 54 +/- 3 mm Hg) patients with chronic obstructive pulmonary disease (COPD). At 24 hours (after four injections of a bolus of 30 mg of methylprednisolone sodium succinate per kilogram of body weight, given intravenously every six hours), significant differences (P less than 0.05) were an increased cardiac index (3.0 +/- 0.2 to 4.1 +/- 0.2 L/min/sq m), a decreased peripheral vascular resistance (1,186 +/- 100 to 849 +/- 60 dynes/sec/cm-5), an increased flow of oxygen to tissue (0.90 +/- 0.07 to 1.16 +/- 0.09 L/min), a decreased arteriovenous oxygen content difference (49 +/- 3 to 43 +/- 2 ml/L), a decreased concentration of hydrogen ions in the arterial blood (38 +/- 1 to 35 +/- 1 nmol/L) and arterial carbon dioxide tension (39 +/- 2 to 32 +/- 1 mm Hg), and increased levels of lactate (1.1 +/- 0.2 to 3.7 +/- 1.0 mmol/L) and pyruvate (0.14 +/- 0.04 to 0.37 +/- 0.08 mmol/L). Fractional oxygen utilization, oxygen consumption, the partial pressure of oxygen at which hemoglobin was 50 percent saturated, and the level of 2,3-diphosphoglyceric acid remained unchanged. In vitro studies showed that these patients' red blood cells responded with a significant (more than 35 percent) increase in the level of 2.3-diphosphoglyceric acid when incubated for ten hours with concentrations of methylprednisolone that were much higher (1.0 mg/ml) than those attained in vivo (12.5 microgram/ml). These studies demonstrate that repeated infusions of high doses of steroids in a bolus in stable hypoxemic patients with COPD produce significant physiologic changes but no apparent net gain in the oxygenation of tissues.

Cardiac Output↗
PubMed1977

Selective mediastinoscopy.

Mediastinoscopy is often utilized for staging bronchogenic carcinoma. Whether it should be used routinely or selectively is controversial. Fifty-four patients with bronchogenic carcinoma were prospectively assigned to one of two groups based on the presence (group A) or absence (group B) of one or more of the following criteria: (1) central location; (2) mediastinal nodal enlargement; (3) involvement of laryngeal nerve; and (4) noncentral location plus linear stranding toward the hilum. Mediastinoscopy was performed on all patients in group A. Thoractomy for definitive staging was performed on those patients in group A with negative mediastinoscopic findings for neoplasm and on all patients in group B. Criteria 1, 2, and 3 were found to be valid; 22 of the 27 patients in group A who had any of these criteria had positive mediastinoscopic findings for neoplasm. Criterion 4 per se was found to be invalif; all seven of the patients in group A who had this isolated finding had negative mediastinoscopic findings for neoplasm and had resectable lesions. Twenty-three of the 27 patients in group B had no mediastinal involvement and had resectable lesions. These data indicate that selective mediastinoscopy using criteria 1 through 3 reduces the number of negative examinations and unnecessary thoracotomies to a minimum.

Humans↗
PubMed1975

Impaired water handling in chronic obstructive lung disease.

Impaired water excretion has been described in stable, nonedematous patients with chronic obstructive lung disease (COLD). To elucidate the mechanism involved, we measured basal glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and water, sodium, and solute excretion for 4 hours after water loading (20 ml. per kilogram orally or as D5W intravenously) in two groups of 10 age-matched, hypoxic, stable, nonedematous COLD normocapneic and hypercapneic patients (PCO2 less than or greater than 45 mm. Hg, respectively). In 5 patients of each group, additional measurements of plasma and urine osmolality and plasma vasopressin were made at 30-minute intervals after oral water loading and the results compared to those obtained in 10 normal control subjects. Hypoxic (PO2 61 plus or minus 2 mm. Hg), normocapneic (PCO2 39 plus or minus 1 mm. Hg) patients had normal GFR (114 plus or minus 5 ml. per minute) and ERPF (517 plus or minus 31 ml. per minute) and excreted the load normally (101 plus or minus 5 per cent of oral or intravenous water per 4-hours). This was associated with a normal rate of sodium excretion (34 plus or minus 5 mEq. per 4-hours) and low-normal plasma vasopressin (1.9 plus or minus 0.7 pg. per milliliter) which was suppressed appropriately with water loading. Hypercapneic (PCO2' 62 plus or minus 5), hypoxic (PCO2' 57 plus or minus 2) patients had normal GFR (106 plus or minus 7), low baseline vasopressin (1.1 plus or minus 0.2) which was suppressed appropriately, and decreased (p less than 0.05) 4-hour water excretion (63 plus or minus 8 per cent), 4-hour sodium excretion (15 plus or minus 9), and ERPF (394 plus or minus 31). A significant correlation was observed between impaired water and impaired sodium excretion (p less than 0.05). These studies indicate that in COLD patients: (1) hypercapnia but not hypoxemia is related to the abnormal water handling and to the increased reabsorption of sodium by the renal tubule; (2) the defect in water excretion is not related to abnormal vasopressin secretion or metabolism; (3) the alteration in sodium excretion may be due to hypercapneic-induced increase in renal bicarbonate reabsorption and/or abnormal renal blood flow.

Adult↗