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Biomedical subjects

N Fogh-Andersen

Publications and source records attributed to N Fogh-Andersen.

At least 91 records · Page 5Linked to original sources
PubMed1989

Comparison of serum total calcium, albumin-corrected total calcium, and ionized calcium in 1213 patients with suspected calcium disorders.

The correlations between serum ionized calcium, serum total calcium, total calcium corrected for albumin and calculated ionized calcium were investigated in a prospective multicentre investigation of 1213 patients suspected of having calcium metabolic disease. Diagnostic discordance between serum total calcium and measured ionized calcium was found in 31% of the patients. With the calculation of albumin-corrected total calcium or calculated ionized calcium the discordance decreased to 17.9%. The diagnostic discordance which could be ascribed to the analytical imprecision (CV = 1.5%) amounted to only 6.7%. Although we found highly significant correlations between the parameters, a considerable scatter around the regression line made prediction of ionized calcium from albumin-corrected total calcium unreliable in many patients.

Algorithms↗
PubMed1988

Serum magnesium, calcium, phosphate and PTH following long-term beta-blockade in ischaemic heart disease.

In 40 patients with ischaemic heart disease the serum levels of magnesium, parathyroid hormone (PTH), phosphate, calcium, and ionized calcium remained unchanged and within normal limits following treatment for 12 months with alprenolol (n = 20) or placebo (n = 20). No changes occurred during a 2 week withdrawal period. The clinical implication is that the non-cardioselective betablocker alprenolol can be given to patients with ischaemic heart disease without the risk of inducing potentially cardiotoxic disturbances in serum magnesium and serum calcium levels. Whether this applies to cardioselective beta-blockers remains to be established.

Adrenergic beta-Antagonists↗
PubMed1988

Secondary hyperparathyroidism of morbid obesity regresses during weight reduction.

In order to test the relation between obesity and the secondary hyperparathyroidism found in markedly overweight subjects, 24 morbidly obese patients were studied before and after a weight loss of 35.9 kg obtained by a nutritionally adequate, intermittent very-low-calorie diet. Overweight was reduced from 98 +/- 34% to 44 +/- 19%. Serum total calcium did not change, but serum ionized calcium (Ca2+) increased from 1.22 +/- 0.04 mmol/L to 1.25 +/- 0.04 mmol/L (P less than .001). A corresponding fall was observed in serum parathyroid hormone (s-PTH), which decreased from 47.2 +/- 21.7 pmol/L to 35.2 +/- 19.4 pmol/L (P = .01). The change of s-PTH was positively associated with the reduction of body weight (r = .50, P less than .05) and with the reduction of overweight (r = .55, P less than .01). Regarding calcium binding substances, serum albumin remained low. The initially lowered serum phosphate and bicarbonate both rose (P less than .001). Plasma lactate and plasma free fatty acids (FFAs) decreased (P less than .001). The study supports our hypothesis that the change profile of calcium complexing anions in obesity interferes with the tubular reabsorption of calcium, which in turn lowers serum Ca2+, thus promoting hyperparathyroidism. Along with weight loss, concentrations of calcium complexing anions returns towards normal values and the secondary hyperparathyroidism regresses.

Adult↗
PubMed1988

Coronary and skeletal muscle enzyme changes during a 14 km run.

Increasing coronary enzyme values have previously been demonstrated after physical exercise. In the present study serum values of aspartate aminotransferase (ASAT), lactate dehydrogenase (LDH), LDH isoenzymes, creatinine kinase (CK), and the myocardial-bound fraction of this enzyme (CK-MB) were measured in a random sample of healthy non-smoking, physically fit men before and immediately after a competitional 14 km run. All enzyme values increased during the run, ASAT by 7%, LDH by 25%, CK by 38%, and CK-MB by 53%. Measurement of LDH isoenzymes showed special increments of the non-cardiac fractions. However, absolute increments of the cardiac fractions of the LDH isoenzymes together with other serum enzyme elevations do not exclude a cardiac source of enzyme release during and following physical exercise.

Adult↗
PubMed1988

Gas-chromatographic measurement of carboxyhemoglobin in blood from mothers and newborns.

HbCO in blood sampled from 20 mothers and newborns immediately after birth was measured with a new, simple gas-chromatographic method for CO. The mean ratio of HbCO to total hemoglobin for 13 non-smoking mothers did not differ significantly from that for their infants (mean 0.38%, SD 0.26% vs 0.38%, SD 0.13%), but the HbCO ratio varied more in the mothers than in the infants (P less than 0.05). The infants of seven cigarette-smoking mothers, tobacco-abstinent for 7 h during labor, had higher HbCO ratios than their mothers (mean 1.88% vs 1.28%, P less than 0.05). The results are in harmony with the concept of equal affinities of fetal and adult hemoglobin for CO and a long time for passage of CO across the placenta.

Carboxyhemoglobin↗
PubMed1987

Diode-array spectrophotometry for simultaneous measurement of hemoglobin pigments.

A prototype oxygen saturation meter was used to measure the concentrations of deoxygenated hemoglobin (rHb), oxyhemoglobin (HbO2), carboxyhemoglobin (HbCO), methemoglobin (MetHb), and sulfhemoglobin (SHb) in 35 microliter blood. Simultaneous absorbance measurements at 535, 560, 577, 622, 636, and 670 nm permitted the composition of any hemoglobin pigment mixture to be determined more accurately, precisely and easily than before. The inclusion of 670 nm, where the hemoglobin pigments have low absorption coefficients, allowed correction for turbidity.

Adult↗
PubMed1987

Spectrophotometric determination of hemoglobin pigments in neonatal blood.

Fetal and adult hemoglobin pigments have slightly different light absorption coefficients. Blood from newborns therefore gives inaccurate results with a direct spectrophotometric determination of hemoglobin pigments (Radiometer's OSM3), if the absorption coefficients for adult blood are used. We determined an absorption coefficient matrix for hemoglobin pigments in twenty full term newborns' blood. This matrix yielded results accurate to within 0.2% in 40 further newborns, but the accuracy of the results varied with the individual ratio of fetal to total hemoglobin, which was 80 +/- 5% (SD) in the examined samples. The OSM3's inaccuracy with the adult absorption coefficients can be used to directly estimate the ratio of fetal to total hemoglobin in an infant.

Adult↗
PubMed1987

Serum phosphate increase during short-term beta-adrenoceptor blockade in thyrotoxicosis.

We studied the changes in blood plasma electrolytes during acute and short-term treatment with four different beta-adrenergic-blocking agents in 31 patients with hyperthyroidism. Serum phosphate increased during the first four hours and remained elevated after one week both after cardioselective (acebutolol) and non-cardioselective (oxprenolol, pindolol and timolol) beta-blockade (p less than 0.05). Albumin decreased after four hours but no change was found after one week. Serum creatinine increased after one week in the acebutolol-treated group, while sodium, potassium and albumin-corrected calcium in serum did not change. The hyperphosphatemic effect may be due to blockade of beta 1-adrenoceptors, since the effect of the cardioselective acebutolol was no less than that of the non-cardioselective beta-adrenoceptor blockers.

Acebutolol↗
PubMed1987

Pulse oximetry versus transcutaneous pO2 in sick newborn infants.

A pulse oximeter (Ohmeda Biox 3700) and two transcutaneous systems (Radiometer TCM3) were applied simultaneously to 18 newborn infants with respiratory insufficiency. All infants had either an umbilical catheter placed in the mid thoracic aorta or a radial artery catheter. The average monitoring time was 2 hours. Arterial blood pO2, pCO2 and pH (Radiometer ABL300), arterial sO2, HbCO and metHb (Radiometer OSM3), erythrocyte 2,3 DPG concentration, and fetal hemoglobin fraction (alkali denaturation kinetic method) were measured. Using arterial sO2 and pO2 as reference, the analytical bias of pulse oximetry (-0.5 +/- 1.0%, mean +/- 1 SD) corresponded in magnitude, when converted to pO2, to that of transcutaneous - pO2 (0.6 +/- 1.4 kPa for combined O2-CO2 electrode and -0.1 +/- 2.3 kPa for single O2 electrode). Transcutaneous pCO2 showed the smallest bias (0.3 +/- 0.3 kPa). Both pulse oximetry and transcutaneous pO2 electrodes were good as trend monitors detecting rapid changes in the infants' oxygenation status. The pulse oximeter offers certain advantages in not requiring calibration or heating. The variations in the levels of fetal hemoglobin fraction (44 to 97%), pH (7.27 to 7.49), pCO2 (3.3 to 6.8 kPa) and 2,3 diphosphoglycerate concentration (1.6 to 5.9 mmol/l) between the infants studied, resulted in a variable pO2-sO2 relation (p50 2.5 to 3.5 kPa). This presents difficulties in interpreting sO2 values in sick newborn infants, and we therefore recommend caution in using a pulse oximeter to apply strict limits for avoiding hypoxia and hyperoxia in this population.

Blood Gas Monitoring, Transcutaneous↗
PubMed1987

Fiber-optic chemical sensors (Gas-Stat) for blood gas monitoring during hypothermic extracorporeal circulation.

Measurements of pO2, pCO2 and pH by optical fluorescence microsensing technology has recently become available for monitoring blood gases during extracorporeal circulation ECC). We have compared simultaneous measurements with fiber-optic sensors (Gas-Stat, Bentley) and electrochemical sensors (ABL-4, Radiometer) on discrete samples. In 10 patients undergoing coronary artery bypass grafting during hypothermic (25 degrees C) ECC and hemodilution (hemoglobin concentration 4 mmol.l-1) arterial and venous pO2, pCO2 and pH were measured in-line in the extracorporeal circuit at the actual blood temperature. Simultaneous and anaerobically collected blood samples in glass syringes were analyzed within five minutes at 37 degrees C in the ABL-4. Linear regression analysis of the values at actual temperature shows the following equations: Gas-Stat = Y, ABL-4 = X: pO2 (kPa): Y = 1.04 X + 0.5 r = 0.95 n = 136; pCO2 (kPa): Y = 0.71 X + 1.5 r = 0.79 n = 136; pH: Y = 0.788 X + 1.590 r = 0.76 n = 136. The advantage of the Gas-Stat is continuous monitoring of blood gas parameters during ECC. The present study shows that measurements of pO2, pCO2 and pH with fiber-optic chemical sensors may be reliable. The differences between the two principles of measurement may be due to unknown factors interfering with the in-line measurements or to variations in sensitivity and stability of the individual sensor.

Blood Gas Analysis↗
PubMed1986

Increased parathyroid hormone as a consequence of changed complex binding of plasma calcium in morbid obesity.

To evaluate whether changed plasma calcium binding might lead to a secondary increase of parathyroid hormone in morbid obesity, fasting measurements of serum ionized, ultrafiltrable and total calcium, calcium binding substances, and parathyroid hormone were undertaken in age- and sex-matched groups of obese (n = 44) and normal weight subjects (n = 52). The 24-hour urinary calcium excretion and clearance of creatine were also measured. Calcium binding to proteins was changed. Serum total proteins and protein-bound calcium did not differ, but serum albumin was decreased in obesity. Consequently, obese subjects did not reveal the normal dependency of protein-bound calcium upon albumin. Calcium binding to other substances was also changed. Serum phosphate and bicarbonate were decreased, while the concentrations of citrate, lactate, acetoacetate, 3-hydroxybutyrate, free fatty acids, and urate were all increased, leaving the total concentration of plasma complex-bound calcium unchanged. Nevertheless, these reciprocal changes increase the concentrations of less readily reabsorbable anions in the renal ultrafiltrate. The changed pattern of calcium binding in serum of the obese subjects may serve to explain our findings of increased urinary calcium excretion, lowering of serum ionized calcium and increased parathyroid hormone levels, changes being significantly correlated with degree of overweight.

Adult↗
PubMed1985

Are sodium bicarbonate and potassium bicarbonate fully dissociated under physiological conditions?

In solutions containing 160 mmol/l Na+ and K+, respectively, measurements with an ion-selective electrode system (KNA1, Radiometer), showed apparent falls in the respective Na+ and K+ concentrations when C1- was replaced by HCO3-. After correction for the change in liquid junction potential, the fall was 9.2 mmol/l for Na+ and 7.3 mmol/l for K+. On the basis of these findings we conclude that sodium bicarbonate and potassium bicarbonate are not fully dissociated in solution, and that NaHCO3(0) and KHCO3(0) do exist as chemical components with association constants of 0.72 and 0.55, respectively. Using these association constants, normal plasma will contain 1.2 mmol/l NaHCO3(0) and 0.03 mmol/l KHCO3(0). Thus NaHCO3(0) accounts for virtually the same amount of CO2 as the physically dissolved fraction. A review of all the currently known CO2 species in plasma suggests that there may be a residue of about 2 mmol/l of unknown CO2 species in normal plasma.

Bicarbonates↗
PubMed1985

Sampling and storage of blood for determination of ionized calcium.

We report some new procedures for the determination of ionized calcium using a semi-automatic ICA 1 analyser provided with a new flow-through tonometer unit, TNC 1, in connection with an automatic turntable. Ionized calcium calculated to a standard pH of 7.4 (cCa2+(7.4)) was not significantly different for capillary blood, venous blood and serum in healthy adults; however, a significant difference was found for actual ionized calcium (cCa2+). The effect of erythrocytes on the liquid junction potential was eliminated by use of a new salt bridge solution (sodium formate). Serum samples should be taken as anaerobically as possible to avoid precipitation of calcium complexes when pH increases above 7.9. For measurement of cCa2+-pH we developed special capillary tubes. Serum could be stored at 4 degrees C for 7 days and at -20 degrees C for 45 days without significant change in cCa2+(7.4). Capillary blood could be stored at 4 degrees C for 4 h without significant change in cCa2+ and pH or at 4 degrees C or 20 degrees C for 24 h without significant change in cCa2+(7.4). Vein puncture with stasis or muscular exercise caused only a small increase in cCa2+(7.4) (1.5%). The ingestion of food did not affect cCa2+ in healthy adults. 97.5% CO2 equilibrium was obtained in 3 min with the new flow-through tonometer.

Air↗