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N Fogh-Andersen

Publications and source records attributed to N Fogh-Andersen.

At least 73 records · Page 4Linked to original sources
PubMed1991

Guidelines for routine measurement of blood hemoglobin oxygen affinity. IFCC Scientific Division, Committee on pH, Blood Gases, and Electrolytes.

Two methods for the routine determination of blood hemoglobin oxygen affinity are described. Both methods use whole blood and do not require special equipment, tonometry, or special gas mixtures. The first method consists of a one-point determination of p 50, and requires only 200 muL to 400 muL of whole blood, therefore making it suitable for the pediatric population. The second method uses multiple points, thereby establishing both the shape and position of the hemoglobin oxygen equilibrium curve between 10 and 99% oxygen saturation. Interpretation of p 50 is discussed in relation to evaluation of patients with hemoglobinopathies and as a parameter in estimating availability of oxygen to the tissues.

Blood Gas Analysis↗
PubMed1990

The effect of different doses of nasal salmon calcitonin on plasma cyclic AMP and serum ionized calcium.

To investigate the effect of low doses of intranasal salmon calcitonin on plasma cyclic AMP (cAMP) and serum ionized calcium, 40 healthy postmenopausal women were randomized to receive a single dose of either placebo or 50, 100, or 200 IU of salmon calcitonin as a nasal spray. Blood samples were collected throughout an 8-hour period. None of the doses could provoke detectable hypocalcemia, whereas 100 and 200 IU of salmon calcitonin were associated with an increase in plasma cAMP after 15 minutes. Measurable plasma levels of salmon calcitonin were demonstrated in all active treatment groups, and the calculated areas under the curves showed a dose-dependent increase.

Administration, Inhalation↗
PubMed1990

Does N-acetylcysteine increase the excretion of trace metals (calcium, magnesium, iron, zinc and copper) when given orally?

N-Acetylcysteine (NAC) is known to decrease the exacerbation rate in patients with chronic bronchitis. It has also been shown that NAC has both an oxygen-radical scavenger and a heavy-metal chelating effect in high intravenous doses. In a study lasting 5 weeks, 10 healthy volunteers were treated with NAC 200 mg t.d.s. for two weeks. The concentrations of trace metals (Ca, Mg, Fe, Zn & Cu) in plasma were measured weekly and daily in a morning spot urine during the investigation. No significant change in plasma concentration or excretion was found during the two weeks of treatment, implying that additional administration of trace metals is unnecessary for patients treated perorally with a therapeutic dose of NAC.

Acetylcysteine↗
PubMed1990

Direct reading glucose electrodes detect the molality of glucose in plasma and whole blood.

It is the activity that determines the direction of chemical processes, transport, etc. and thus provides the clinically more relevant information. Direct reading glucose electrodes consume glucose at a rate proportional to the glucose activity in the sample. The activity equals the molality (mmol glucose per kg water), so results from direct reading glucose electrodes must differ from the conventionally measured glucose concentration. This was observed in 159 whole blood samples which gave higher results from a direct reading glucose electrode than by our conventional method (y = 1.21x - 0.37 mmol/l). However, adjustment for the different water concentration due to salt, plasma proteins, and hemoglobin occupying space, gave results equal to the concentrations (y = 1.00x - 0.28 mmol/l, r = 0.997). Furthermore, results for samples with constant glucose concentration and varying albumin concentration correlated with the albumin concentration (r = 0.989), but not after adjustment for water concentration (r = 0.037, n.s.).

Blood Chemical Analysis↗
PubMed1990

Overall renal and tubular function during infusion of amino acids in normal man.

1. Amino acids have been used to test renal reserve filtration capacity. Previous studies suggest that amino acids increase glomerular filtration rate (GFR) by reducing distal tubular flow and tubuloglomerular feedback activity. 2. Glomerular function and the renal tubular handling of sodium during infusion of amino acids was studied in 12 normal volunteers. 3. Clearance of sodium (CNa) was unchanged. Effective renal plasma flow increased slightly, but significantly, by 9% (P less than 0.05). GFR was increased by 13% (P less than 0.001). Clearance of lithium (CLi) (used as an index of proximal tubular outflow) increased by 38% (P less than 0.001). Calculated absolute proximal reabsorption (GFR-CLi) remained unchanged. Fractional proximal reabsorption [1-(CLi/GFR)] was decreased by 10% (P less than 0.001). Calculated absolute distal sodium reabsorption [(CLi-CNa) x PNa, where PNa is plasma sodium concentration] increased by 40% (P less than 0.001). Plasma renin concentration did not change significantly. 4. The results suggest that amino acids increase GFR by a primary effect on renal haemodynamics or, less likely, by reducing the signal to the tubuloglomerular feedback mechanism. The increase in proximal tubular outflow was compensated for in the distal tubules, so that the sodium excretion rate remained unchanged.

Absorption↗
PubMed1990

Renal tubular reabsorption of sodium and water during infusion of low-dose dopamine in normal man.

1. Using the renal clearance of lithium (CLi) as an index of proximal tubular outflow of sodium and water, together with simultaneous measurements of effective renal plasma flow, glomerular filtration rate (GFR) and sodium clearance (CNa), renal function and the tubular segmental reabsorption rates of sodium and water during dopamine infusion (3 micrograms min-1 kg-1) were estimated in 12 normal volunteers. 2. CNa increased by 128% (P less than 0.001). Effective renal plasma flow and GFR increased by 43% (P less than 0.001) and 9% (P less than 0.01), respectively. CLi increased in all subjects by, on average, 44% (P less than 0.001). Fractional proximal reabsorption [1-(CLi/GFR)] decreased by 13% after dopamine infusion (P less than 0.001), and estimated absolute proximal reabsorption rate (GFR-CLi) decreased by 8% (P less than 0.01). Absolute distal sodium reabsorption rate [(CLi-CNa) x PNa, where PNa is plasma sodium concentration] increased (P less than 0.001), and fractional distal sodium reabsorption [(CLi-CNa)/CLi] decreased (P less than 0.001). 3. It is concluded that natriuresis during low-dose dopamine infusion is caused by an increased outflow of sodium from the proximal tubules that is not fully compensated for in the distal tubules.

Absorption↗
PubMed1990

The oxygen status of the arterial blood revised: relevant oxygen parameters for monitoring the arterial oxygen availability.

The new generation of very accurate multi-wavelength oximeters, e.g. OSM3, for in vitro measurement of the hemoglobin oxygen saturation, total hemoglobin concentration, and carboxy- and methemoglobin fractions opens new aspects of oxygen monitoring. Combined with the data from the blood gas analyzer (e.g. ABL300) these very accurate measurements allow the calculation of several derived oxygen parameters on the basis of a set of newly developed calculation algorithms. The traditional parameters obtained from an arterial sample are the oxygen tension (pO2) and the hemoglobin oxygen saturation (sO2). Clinical examples illustrate that the pO2 and the sO2 even in combination may give misleading information. The new algorithm calculates three extra oxygen parameters. 1) The oxygen extraction tension, px, defined as the tension required to extract 2.3 mmol of oxygen per liter blood. It signals the mixed venous pO2 level on the assumption that the arterio-venous oxygen difference is normal (2.3 mmol/L). 2) The concentration of extractable oxygen, cx, defined as the concentration of oxygen extracted at a tension of 5.0 kPa. 3) The oxygen compensation factor, Qx, derived as (2.3 mmol/L)/cx. It may be interpreted as the increase in cardiac output necessary to maintain a normal mixed venous pO2 of 5 kPa. These three parameters indicate the oxygen availability of the blood and summarize important properties of the arterial blood in relation to oxygen supply of the tissues, including the arterial pO2, the 'active' hemoglobin concentration (equivalent to the oxygen capacity), and the hemoglobin oxygen affinity (p50). The set of data measured with the blood gas analyzer, e.g. the ABL300 combined with the data measured with the OSM3 contains much more information than is routinely utilized. This information is extracted and summarized by our calculation algorithm. Omitting the calculation of the extra oxygen parameters involves a risk of losing valuable information.

Arteries↗
PubMed1990

Arterial oxygen status determined with routine pH/blood gas equipment and multi-wavelength hemoximetry: reference values, precision, and accuracy.

We measured pH, pCO2, pO2, oxygen saturation, total hemoglobin concentration, and fractions of carboxy- and methemoglobin in arterial blood samples from 35 healthy adults. We used a new algorithm to calculate active hemoglobin concentration, total oxygen concentration, actual half-saturation tension, 2,3-diphosphoglycerate concentration, estimated functional shunt, oxygen extraction tension px (for extracting 2.3 mmol of oxygen per liter of blood, values below 4.5 kPa indicating risk of tissue hypoxia), and the oxygen compensation factor Qx (the factor by which the cardiac output should rise to maintain a normal mixed venous pO2 of 5.0 kPa, factors above 1.5 indicating an extra burden on the heart). Analytical precision was evaluated by duplicate determinations. The accuracy of the half-saturation tension was evaluated by comparison with values for simultaneously drawn venous blood, the accuracy of the calculated concentration of 2,3-diphosphoglycerate by comparison with direct enzymatic measurements. We conclude that all the variables may be determined with sufficient accuracy and precision in healthy adults, provided the oxygen saturation is less than 0.97 and the measurements are performed according to the highest state of the art.

2,3-Diphosphoglycerate↗
PubMed1990

Accurate measurements of hemoglobin oxygen saturation, and fractions of carboxyhemoglobin and methemoglobin in fetal blood using Radiometer OSM3: corrections for fetal hemoglobin fraction and pH.

The differences in the visible absorption spectra between fetal and adult oxyhemoglobin and carboxyhemoglobin result in errors in the measurements og hemoglobin oxygen saturation (SO2) and carboxyhemoglobin fraction (FCOHb) in fetal blood, if not corrected for the actual fetal hemoglobin fraction (FHbF) in the sample. In 11 fully oxygenated umbilical cord blood samples (mean FHbF = 77%), we found a mean positive bias in SO2 of 4.7%, and in FCOHb of 2.7%, when measured with a dedicated spectrophotometer (OSM3, Radiometer A/S, Denmark), and using the matrix of absorption coefficients for adult hemoglobin. Accurate measurements were obtained by using OSM3's correction for FHbF in the blood specimen after measurement of FHbF by OSM3. The effects of plasma pH on the measurements of SO2 and FCOHb in fully oxygenated fetal blood were found to be similar to those found for adult blood. From plasma pH 7.05 to 8.02, measured SO2 increased 1.3% and FCOHb 0.6%. Correction for the pH of fetal blood samples should be considered when calibrating OSM3 and in connection with research studies. The effects of FHbF and pH on the measurement of methemoglobin fraction (FMetHb) were less than 0.2%, and can be ignored. FHbF measured by OSM3 at pH 7.4 is about 14% too high compared to alkali denaturation rate method. However, the presence of a metabolic acidemia, which is common in fetal blood specimens, decreases this bias, so that for example in our study, FHbF, measured by OSM3 and uncorrected for pH changes was on average only 6% too high. We recommend that OSM3's factor of 18.6 is reduced to 16.4, and that correction is made for pH.

Carboxyhemoglobin↗
PubMed1990

pH effect on the COHb absorption spectrum: importance for calibration of the OSM3 and measurement of circulating hemoglobin and blood volume.

An easy method to measure blood volume is clinically needed. We used carbon monoxide (CO) and the OSM3 to measure circulating hemoglobin and blood volume with the indicator dilution principle. 50 mL of CO was administered into a closed rebreathing system and taken up via the lungs, and the amount of hemoglobin in the blood was calculated from the increase in carboxyhemoglobin fraction after 10 min. Blood volume was calculated by division with the concentration of hemoglobin. We observed that the absorption spectrum of carboxyhemoglobin (COHb) depends on pH and pCO2, which must be controlled when very accurate spectrophotometry is necessary. The bias is 3% COHb per pH unit during calibration of the OSM3, which may be permissible for patients with CO poisoning, but not for the present purpose. With this in mind the method is very accurate, precise and simple.

Blood Volume↗
PubMed1990

Guidelines for routine measurement of blood hemoglobin oxygen affinity. International Federation of Clinical Chemistry, Scientific Division, Committee on pH, Blood Gases and Electrolytes.

Two methods for the routine determination of blood hemoglobin oxygen affinity are described. Both methods use whole blood and do not require special equipment, tonometry or special gas mixtures. The first method consists of a one-point determination of p50, and requires only 200 microL to 400 microL of whole blood, therefore making it suitable for the pediatric population. The second method uses multiple points, thereby establishing both the shape and position of the hemoglobin oxygen equilibrium curve between 10 and 99% oxygen saturation. Interpretation of p50 is discussed in relation to evaluation of patients with hemoglobinopathies and as a parameter in estimating availability of oxygen to the tissues.

Abbreviations as Topic↗
PubMed1990

Adjusted ionized calcium (at pH 7.4) and actual ionized calcium (at actual pH) in capillary blood compared for clinical evaluation of patients with disorders of calcium metabolism.

We report results for adjusted ionized calcium (at pH 7.4) and actual ionized calcium (at actual pH) in capillary blood from 183 patients with disorders of calcium metabolism (primary hyperparathyroidism, secondary hyperparathyroidism of malabsorption, primary hypoparathyroidism, Paget's disease, acromegaly, hypercalcemia of malignancy, osteoporosis, sarcoidosis, idiopathic hypercalciuria, and familial hypocalciuric hypercalcemia). The correlation and the equation for the linear regression between adjusted ionized calcium (y) and actual ionized calcium (x) were y = 1.011x + 0.005 mmol/L, r = 0.992, Sy,x = 0.021 mmol/L. Results were similar within each diagnostic group. Consistent agreement between adjusted and ionized calcium was observed in 96.7% of patients representing a variety of the most frequently encountered disorders of calcium metabolism. Thus we find adjusted ionized calcium to be as useful as actual ionized calcium for evaluation of patients with such disorders. Adjusted ionized calcium may therefore also be a logical choice for establishing agreement between laboratories for reference intervals in healthy adults.

Acromegaly↗
PubMed1989

[Ionized calcium, total calcium and albumin corrected calcium in the serum in 1213 patients with suspected calcium metabolic diseases. A prospective multicenter study].

The correlation between serum ionized calcium, serum total calcium and albumin corrected total calcium was investigated in a prospective multicentre investigation of 1,213 patients with suspected calcium metabolic disease. 31.0% of the patients were misclassified when serum total calcium was measured instead of serum ionized calcium. The diagnostic discrepancy between the two methods decreased with the calculation of albumin corrected total calcium or calculated ionized calcium (17.9%). On justing for the analytical error connected with the measurement of ionized calcium, 11.2% of the patients were still misclassified. It is not possible precisely to predict serum ionized calcium from the measurement of serum total calcium and we recommend measurement of serum ionized calcium in patients believed to have calcium metabolic disease.

Calcium↗
PubMed1989

[Cimetidine and creatinine clearance].

Cimetidine lowers secretion of creatinine in the renal tubuli in healthy individuals and persons with chronic renal disease. The conditions in patients with renal transplants have hitherto been unknown. The renal clearance of endogenic creatinine (CKrea) was investigated prior to and after an intravenous bolus injektion of cimetidine (5 mg/kg) in nine patients with renal transplants. The rate of glomerular filtration (GFR) was determined by clearance investigation of 125I-thalamate (CTh). CKrea fell 29% from 65 ml/min (median) to 46 ml/min (p less than 0.01), whereas GFR remained unchanged. The fractionated creatinine clearance (CKrea/CTh) fell therefore from 1.43 (median) to 1.03 (p less than 0.01). It is concluded that cimetidine reduces creatinine secretion in patients with renal transplants and this should be borne in mind when the function of the graft is assessed solely with CKrea.

Adult↗
PubMed1989

[Oxygen status of arterial blood including uncompensated mixed venous oxygen tension and cardial oxygen compensation factor. Reevaluation on the basis of 250 arterial punctures].

In arterial blood from 250 patients we measured pH, pco2, and po2 (electrochemically) together with total-hemoglobin concentration, oxygen saturation, carboxy- and methemoglobin fractions (spectrometrically). With a previously published algorithm we calculated the effective hemoglobin concentration, total-oxygen concentration, half saturation tension, erythrocyte 2,3-diphosphoglycerate concentration, and two new oxygen parameters: uncompensated mixed venous oxygen tension and cardiac oxygen compensation factor. 11% of the patients have normal arterial oxygen tension, but nevertheless risk of tissue hypoxia judged from the two new oxygen parameters. This is due to a low hemoglobin concentration and/or low half saturation tension (increased hemoglobin oxygen affinity). Some patients have decreased arterial oxygen tension but normal uncompensated mixed venous oxygen tension (15%) or normal cardiac oxygen compensation factor (9%). This is due to a high hemoglobin concentration and/or increased half saturation tension. The latter varies from 2.6 to 5.2 kPa (ref.: 3.3-3.9 kPa); 36% have decreased, 27% increased values. The 2,3-diphospho-glycerate concentration varies from 2.0 to 7.9 mmol/l (ref.: 3.6-5.1 mmol/l); 14% have decreased, 30% increased values. Uncompensated mixed venous oxygen tension varies from 1.8 to 5.7 kPa (ref.: 4.5-5.5 kPaf). The cardiac oxygen compensation factor varies from 0.9 to infinity (ref.: 0.8-1.6). We conclude that the variation in the different oxygen parameters is so significant that it justifies routine calculation for all arterial blood samples where the measurement on a conventional blood gas analyzer is supplemented with measurement on one of the new multi-wavelength hemoximeters. The calculation algorithm permits calculation of all the oxygen parameters for the majority of arterial samples (84%) where the oxygen saturation is less than or equal to 0.970.

Adult↗
PubMed1989

Changes in serum phosphate during beta-blockade in healthy men are not due to changes in the renal handling of phosphate.

Serum parathyroid hormone (PTH), phosphate, ionized calcium, magnesium, alkaline phosphatase and creatinine and the urinary excretion of phosphate and creatinine were studied after 1 and 3 weeks beta-blockade in 32 young healthy men given either atenolol at 50 mg, metoprolol at 100 mg, propranolol at 80 mg or placebo twice a day. After 1 week treatment serum phosphate (mean (range] increased in the propranolol-treated subjects (1.17 (0.99-1.30) to 1.32 (1.08-1.71) mmol l-1 (P = 0.03), minor changes were found in the atenolol and the metoprolol-treated subjects but not in the placebo group. Serum phosphate was unchanged compared to pretreatment values after 3 weeks. Renal clearance and urinary excretion of phosphate and creatinine was unchanged after both 1 and 3-weeks treatment. Serum PTH, ionized calcium, magnesium and alkaline phosphatase were unchanged in all groups, whereas serum urate and creatinine increased in the metoprolol-treated subjects after both 1 and 3 weeks.

Adult↗
PubMed1989

The effects of cimetidine on creatinine excretion, glomerular filtration rate and tubular function in renal transplant recipients.

The renal clearance of endogenous creatinine (CCr), sodium (CNa) and lithium (CLi) was determined before and after a single intravenous bolus of cimetidine in nine renal transplant recipients. The glomerular filtration rate (GFR) was measured with 125I-iothalamate clearance (CTh). The initial CCr of 65 ml/min (median) was reduced to a nadir of 46 ml/min (p less than 0.01) during the first 2 h after infusion of cimetidine. GFR remained unchanged, and thus the fractional clearance of creatinine (CCr/CTh) was reduced from 1.43 (median) to 1.03 (p less than 0.01). CNa and the fractional excretion of sodium decreased throughout the study (p less than 0.05); CLi was unchanged. In conclusion cimetidine, when measured during 1-h clearance periods, interferes with tubular creatinine secretion in the denervated kidney of transplant recipients without affecting the glomerular filtration rate or proximal tubular flow. This suggests that on-going cimetidine treatment must be taken into account when graft function is evaluated by the CCr alone.

Absorption↗