Niels Fogh-Andersen

Blood and plasma volumes determined by carbon monoxide gas, 99mTc-labelled erythrocytes, 125I-albumin and the T 1824 technique

The total amount of circulating haemoglobin was measured in 12 subjects using a direct carbon monoxide (CO)-technique. O2 plus 50 ml CO gas was rebreathed in a small closed system for 10 min. Carboxyhaemoglobin (HbCO)% was measured with a diode-array spectrophotometer before and after the rebreathing. delta HBCO% and the amount of CO in moles (nCO) were used to calculate the total amount of circulating haemoglobin. Blood volume was calculated by dividing this figure with the haemoglobin concentration and plasma volume by multiplying the blood volume with 1-haematocrit. The calculated blood and plasma volumes were compared with the simultaneously measured volumes by 99mTc-labelled erythrocytes, 125I-albumin and T 1824 (Evans Blue). Mean blood volume determined with CO was 4557 ml (3251-6576 ml) compared with 4527 ml (3390-6527 ml) with 99mTc-labelled erythrocytes (r = 0.97). Mean plasma volume by T 1824 was 2895 ml (1972-3658 ml) vs 2898 ml (1815-3714) ml using 125I-albumin, (r = 0.99). The plasma volumes calculated from the blood volumes determined by the erythrocyte-labelling methods were 5-10% lower than those measured with labelled albumin. There was a better correlation between the plasma volumes by the albumin methods and by the CO-technique (r = 0.98 and r = 0.97, respectively) than between the plasma volumes by the albumin methods and by 99mTc-erythrocytes (r = 0.90 and r = 0.87, respectively).

Low dose iron supplementation does not cover the need for iron during pregnancy

Objective ‐ To determine: 1) if 18 mg iron daily is sufficient to cover the iron need during normal pregnancy, and 2) if women, who will not need iron supplementation during pregnancy, can be identified by early screening.

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.).

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.

Atrial natriuretic peptide, blood volume, aldosterone, and sodium excretion during twin pregnancy.

Background. The reports on plasma concentrations and physiological function of atrial natriuretic peptide (ANP) during pregnancy are conflicting. In a recent prospective study, including 40 healthy primigravidae, we found a highly significant decrease in the plasma concentration of ANP (p‐ANP) during the third trimester and the results indicated that ANP takes part in regulation of blood volume and renal function during pregnancy as in the nonpregnant state. In order to test these results, a study was performed in primigravidae with twin pregnancy to test if the accentuated physiological changes here were followed by a corresponding greater decrease in p‐ANP.

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

SummaryTo 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.

Evaluation of the Gas-STAT® fluorescence sensors for continuous measurement of pH, pCO2 and pO2 during cardiopulmonary bypass and hypothermia

Continuous measurement of pH, pCO2 and pO2 during extracorporeal circulation has become feasible using disposable fluorescence sensors (optodes). We have evaluated a commercial system: Gas-STAT (American Bentley) by reference to in-vitro measurements on discrete samples using conventional electrochemical sensors (BMS-3, Radiometer). The Gas-STAT measures at the actual temperature of the blood in the extracorporeal circuit. The reference measurements were performed at two fixed temperatures of 25 and 37 °C with interpolation of the values to the actual temperature of the Gas-STAT.10 patients undergoing coronary artery bypass grafting during hypothermic extracorporeal circulation with hemodilution were monitored in the venous as well as the arterial line with the Gas-STAT with 6–9 samplings of arterial and venous blood from each patient, a total of 136 samples.The comparisons revealed a large scatter which was due partly to inter-optode partly to intra-optode variation and partly to a memory effect which re...

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.

Effects of the prostacyclin analogue iloprost on cyclosporin-induced renal hypoperfusion in stable renal transplant recipients

BACKGROUND The synthetic prostacyclin analogues have been proposed to protect against cyclosporin A (CsA) nephrotoxicity. The present study investigated the effect of infusion of the prostacyclin analogue iloprost on the acute CsA-induced renal hypoperfusion and hypofiltration in stable renal-transplant recipients. METHODS The study included 10 stable renal-transplant recipients with good graft function (s-creatinine 90-170 micromol/l). Renal function and the acute renal haemodynamic and tubular response to an oral CsA-dose (Sandimmun Neoral, 3 mg.kg-1) were investigated with an infusion of iloprost (1 ng.kg-1.min-1) or placebo on 2 separate days. After an overnight fast, seven 30-min renal clearance periods were performed, two before infusion, three during infusion, and two recovery periods. An additional control clearance study without CsA intake or iloprost/placebo infusion was done in eight of the patients. RESULTS CsA ingestion decreased ERPF and GFR significantly with a maximum decline at the end of the clearance study. Iloprost infusion abolished the CsA-induced decrease in ERPF, but had no effect on the CsA-induced decrease in GFR, leading to a significant decline in FF. Renal clearance of lithium (CLi)), used as an index of proximal tulbular outflow, decreased in parallel with GFR after CsA intake, with no additional effects of iloprost. Iloprost infusion decreased blood pressure and increased heart rate. CONCLUSION Infusion of iloprost causes systemic and renal vasodilation, but has no effect on the CsA-induced decrease in GFR and CLi in stable renal transplant recipients.

Haemoglobin oxygen saturation and related quantities: definitions, symbols and clinical use

(1990). Haemoglobin oxygen saturation and related quantities: definitions, symbols and clinical use. Scandinavian Journal of Clinical and Laboratory Investigation: Vol. 50, No. 4, pp. 455-459.