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T Almén

Publications and source records attributed to T Almén.

At least 19 recordsLinked to original sources
PubMed2005

Contrast-medium-Induced nephropathy correlated to the ratio between dose in gram iodine and estimated GFR in ml/min.

PURPOSE: To suggest a more precise tool when assessing the risk of contrast-medium-induced nephropathy (CIN), i.e. the ratio between contrast medium (CM) dose expressed in grams of iodine (g-I) and estimated glomerular filtration rate in ml/min (eGFR; based on equations using serum-creatinine (s-Cr), weight, height, age, and/or sex), here named I-dose/GFR ratio. MATERIAL AND METHODS: A Medline search of published CIN investigations reporting mean eGFR and mean dose of low-osmolality CM (LOCM) identified 10 randomized controlled prophylactic and 2 cohort coronary investigations, and 3 randomized and 1 cohort computed tomographic (CT) investigation. From the randomized trials, data were collected only from the placebo or control arms, unless there was no significant difference between the control and test groups. The mean I-dose/GFR ratio of each study was correlated with the mean frequency of CIN-1 (s-Cr rise> or =44.2 micromol/l or > or =20-25%) and CIN-2 (oliguria or requiring dialysis). A maximum dose according to an I-dose/GFR ratio= 1 in patients with s-Cr ranging from 100 to 300 micromol/l was compared with that of CIGARROA'S formula and with a "European consensus" threshold published by the European Society of Urogenital Radiology, both using s-Cr alone to predict renal function. McCullough's formula was used to assess the risk of CIN requiring dialysis at an I-dose/GFR ratio= 1 with LOCM. RESULTS: The coronary investigations revealed a linear correlation with a correlation coefficient between the I-dose/GFR ratio and the frequency of CIN-1 and CIN-2 of 0.91 (P<0.001) and 0.84 (P=0.001), respectively. At a mean I-dose/GFR ratio= 1, the regression line indicated a 10%) risk of CIN-1 and a 1% risk of CIN-2. At a mean I-dose/ GFR ratio=3, the risk of CIN-1 and CIN-2 increased to about 50% and 15%, respectively. Pooled weighted data from the CT investigations revealed a 12% risk of CIN-1 at a mean I-dose/GFR ratio = 1.1 and no cases of CIN-2. The maximum CM dose according to an I-dose/GFR ratio= 1 was about 30-50% of that of both Cigarroa's formula and the "European consensus" in elderly low-weight individuals, while it was similar for middle-aged individuals weighing about 90 kg. McCullough's formula suggests that there will be an exponentially increasing risk of CIN requiring dialysis, but at an I-dose/GFR ratio= 1 and using LOCM it will not exceed 1% until GFR decreases below 30 ml/min in diabetics and below 20 ml/min in non-diabetics. CONCLUSION: Using the I-dose/GFR ratio may be a more expedient way of improving risk assessment of CIN than today's common practice of estimating CM dose from volume alone and renal function from s-Cr alone. Prospective studies based on individual patient data are encouraged to define the risk of CIN at various I-dose/GFR ratios and correlated to type of CM, examination, risk factors, etc.

Adult↗
PubMed2004

Bone cement X-ray contrast media: a clinically relevant method of measuring their efficacy.

It is important to compare different contrast media used in bone cement according to their ability to attenuate X-rays and thereby produce image contrast between bone cement and its surroundings in clinical applications. The radiopacity of bone cement is often evaluated by making radiographs of cement in air at an X-ray tube voltage of 40 kV. We have developed a method for ranking contrast media in bone cement simulating the clinical situation, by (1) choosing the same X-ray tube voltage as used in clinical work, and (2) using a water phantom to imitate the effects of the patients' soft tissue on the X-ray photons. In clinical work it is desirable to have low radiation dose, but high image contrast. The voltage chosen is a compromise, because both dose and image contrast decrease with higher voltage. Three contrast media (ZrO(2), BaSO(4), and Iodixanol) have been compared for degree of "image contrast." Comparing 10 wt % contrast media samples at an X-ray tube voltage of 40 kV, ZrO(2) produced higher image contrast than the other media. However, at 80 kV, using a water phantom, the results were reversed, ZrO(2) produced lower image contrast than both BaSO(4) and Iodixanol. We conclude that evaluations of contrast media should be made with voltages and phantoms imitating the clinical application.

Barium Sulfate↗
PubMed2002

Contrast medium extravasation injury: guidelines for prevention and management.

Extravasation of contrast material is a well-recognized complication of contrast-enhanced imaging studies. The management of this complication is contentious; therefore, the Contrast Media Safety Committee of The European Society of Urogenital Radiology decided to review the literature and issue guidelines. A comprehensive literature search was carried out. The resulting report was discussed at the 8th European Symposium on Urogenital Radiology in Genoa, Italy. Automated power injection may result in extravasation of large volumes and may or can lead to severe tissue damage. Infants, young children and unconscious and debilitated patients are particularly at risk of extravasation during contrast media injection. Fortunately, most extravasations result in minimal swelling or erythema, with no long-term sequelae; however, severe skin necrosis and ulceration may occur. Large volumes of high osmolar contrast media are known to induce significant tissue damage. Compartment syndrome may be seen associated with extravasation of large volumes. Conservative management is often adequate, but in serious cases the advice of a plastic surgeon is recommended. Based on the review simple guidelines for prophylaxis and management of contrast medium extravasation injuries are proposed.

Adult↗
PubMed2002

Biliary and total extrarenal clearance of inulin and iohexol in pigs. A source of error when determining gfr as body clearance.

Biliary clearance, total extrarenal clearance, body and renal clearance of inulin and iohexol were determined in 11 normal and 11 nephrectomized pigs. The biliary clearance of inulin, calculated as biliary excretion divided by the plasma concentration, was 0.04 and 0.01 ml min(-1) 10 kg(-1) and of iohexol 0.21 and 0.1 ml min(-1) 10 kg(-1), in normal, respectively, nephrectomized pigs (p < 0.05). The extrarenal clearance of inulin, calculated as body minus renal clearance, was 2.7 and 0.7 ml min(-1) 10 kg(-1) and of iohexol 3.7 and 0.7 ml min(-1) 10 kg(-1) in normal, respectively, nephrectomized pigs (p < 0.05). Some hours after injection of the markers their plasma concentrations were much higher in the nephrectomized pigs. This higher plasma concentration was not matched by an equally higher biliary excretion and therefore biliary clearance decreased. The smaller total extrarenal clearance in nephrectomized pigs, i.e. the overestimation of GFR when calculated as body clearance, indicates that this source of error decreases with decreasing renal function.

Animals↗
PubMed2001

Use of spiral CT and the contrast medium iohexol to determine in one session aortorenal morphology and the relative glomerular filtration rate of each kidney.

The aim of this study was to determine the relative glomerular filtration rate (GFR), i.e. the GFR of each kidney in percent of total GFR, by spiral CT. In 41 patients, who were part of a follow-up program after endoluminal stent grafting of aortic aneurysm, spiral CT with the contrast medium iohexol was used to evaluate the morphology of the aorta and kidneys. The opportunity was taken to utilize the already injected iohexol to determine the relative GFR with an extra CT sequence. In each patient two determinations were made, 6 or 12 months apart. The amount of a GFR marker accumulating in Bowman's space, tubuli, and renal pelvis within 2-3 min after i.v. injection, before any marker had left the kidney via the ureter, was defined as proportional to the GFR of that kidney. The renal accumulation of iohexol was obtained by spiral CT using 10-mm collimation and a table speed of 10 mm/s (pitch ratio 1:1) from the upper to the lower poles. The correlation coefficient between the relative GFR of each kidney determined at the first and second examination was excellent (r=0.99) with a median (range) difference of 1% (0-6%) of total GFR. The radiation dose calculated as the mean absorbed dose to the kidneys was 50 mGy and the effective dose 5 mSv. The morphology of aorta and kidneys and the relative GFR of each kidney can be determined in one session with spiral CT using iohexol as both angiographic contrast medium and as a GFR marker. It is also possible to take some plasma samples in the same session to determine iohexol concentration to calculate the body clearance of iohexol (or take plasma and urine samples to calculate the renal clearance of iohexol).

Aged↗
PubMed2000

Assessing residual renal function and efficiency of hemodialysis--an application for urographic contrast media.

BACKGROUND: In patients on hemodialysis with end-stage renal disease there is an increasing interest in measuring both residual renal function (RRF) and quantity and quality of dialysis because insufficient dialysis gives higher mortality. For that purpose we have measured clearances of two urographic iodine (I) contrast media (CM) with different molecular masses (iohexol 821 u and iodixanol 1, 550 u). These CM are filtered through glomeruli and dialysis membranes and have higher molecular masses than urea and creatinine and might represent the dialyzability of the hypothetic uremic toxins with a molecular mass of 300-5,000 u. METHODS: Thirteen patients (8 of them were anuric) immediately after hemodialysis received 15 ml iohexol (300 mg I/ml i.v.) and 2 weeks later in the same way 15 ml iodixanol (320 mg I/ml). Nine other patients (2 anuric) received CM after only one dialysis; 8 got iohexol and 1 got iodixanol. After the CM injections the iodine concentrations were measured with X-ray fluorescence in blood and, when available, urine during the following 2 days including both the start and end of the next dialysis. Eighteen patients after two dialysis sessions, 2 weeks apart, received 10 ml iohexol i.v., and a single blood sample was taken at the start of the next dialysis 2 days later to determine RRF alone. RESULTS: In the 10 anuric patients the extrarenal clearances (mean +/- SD) were 2.5 +/- 1.1 and 2.7 +/- 1.1 ml/min/1.73 m(2) for iohexol and iodixanol, respectively. In patients with RRF good correlations were demonstrated between body clearance, based on two blood samples, and renal clearance of CM. Good correlations (r(2) = 0.853 for iohexol, r(2) = 0.933 for iodixanol) were noted between two-sample and single-sample body clearances. Repeated single sample iohexol clearances gave a coefficient of variation of 15%. During dialysis the clearances of iohexol and iodixanol were, respectively, 69 +/- 16 and 58 +/- 11 ml/min/1.73 m(2) when calculated from a single-pool model (hemodialysis clearance of CM from plasma). A median increase (rebound) of CM concentrations in plasma 45 min dialysis was 8% for iodixanol and 18% for iohexol. When the CM concentration 45 min after dialysis was used, the clearance values were by 8-10% lower and represented the hemodialysis clearance of CM from the extracellular compartments. The dialysis eliminations of iohexol and iodixanol were similar to that of urea, measured as percentage reduction of serum levels during dialysis. CONCLUSIONS: A single injection of CM at the end of dialysis followed by a single blood sample at the start of the next dialysis gives total body clearance, i.e., an estimation of the RRF. An additional blood sample at the end of the next dialysis gives dialysis efficiency.

Adult↗
PubMed1997

Clearance of iohexol, 51Cr-EDTA and endogenous creatinine for determination of glomerular filtration rate in pigs with reduced renal function: a comparison between different clearance techniques.

In order to simplify and/or improve determination of glomerular filtration rate (GFR) the clearances of iohexol, 51Cr-EDTA and endogenous creatinine were simultaneously determined with different techniques in 21 anesthetized landrace pigs. Their GFR had been reduced to about 1/3 or less of normal GFR. After an intravenous bolus of the GFR markers, their plasma concentration curves were followed for 6 hours with 16 plasma samples. A bladder catheter collected urine during six 60-min periods. The plasma clearance was calculated by dividing "dose of marker" with "area under the plasma concentration curve" (AUC) from the time of injection to infinity using a one- (Clprovisional) and a three-compartment (ClAUC-3comp) model. The renal clearance of iohexol and 51Cr-EDTA was calculated by dividing the amount of marker excreted in the urine in a period by AUC in the same period. The AUC was for iohexol and 51Cr-EDTA determined by integrating the total area in the period (Clren adv)-our reference method representing the "true" GFR and for creatinine determined by using the arithmetic mean of the plasma concentration of the marker at the start and at the end of the urine collection period (Clren simple). Renal clearance of creatinine was significantly lower than renal clearance of iohexol (p = 0.0019) and 51Cr-EDTA (p = 0.0001). There were no significant differences between the renal clearances (Clren adv) of iohexol and 51Cr-EDTA or between their plasma clearances (ClAUC-3comp). For iohexol the median overestimation of the "true" GFR with Clprovisional was higher when "early" plasma samples (30-120 min) were used (4.5 ml min-1 10 kg-1) than when late samples (180-360 min) were used (1.9 ml min-1 10 kg-1). Subtraction of the median extrarenal clearance (known from a study of nephrectomized pigs) from the plasma clearances (ClAUC-3comp) of iohexol and 51Cr-EDTA in pigs with reduced renal function decreased the median overestimation of the "true" GFR from 1.9 to 1.0 ml min-1 10 kg-1 with iohexol and from 1.7 to 0.9 ml min-1 10 kg-1 with 51Cr-EDTA. The plasma clearance technique may be improved in pigs with reduced GFR by (i) including a "late" plasma sample in three- and one-compartment models, which tends to increase the AUC; (ii) introducing a correction formula by normalizing the GFR values of the one-compartment model to those of the three-compartment model, thereby compensating for the rapid early changes in plasma concentration of marker after the bolus injection of the marker; or (iii) subtracting a median (or mean) extrarenal clearance of the marker in pigs from the plasma clearance [according to (i) or (ii)]. The plasma clearance one-compartment technique may be improved in pigs with various levels of GFR values by normalizing the plasma clearance values to the renal clearance values, thereby compensating for both the early changes in plasma concentration of marker and the extrarenal clearance of marker.

Animals↗
PubMed1996

Extrarenal plasma clearance of iohexol, chromium-51-ethylenediaminetetraacetic acid, and inulin in anephric pigs.

RATIONALE AND OBJECTIVES: To improve the measurement of the glomerular filtration rate (GFR), we determined the extrarenal plasma clearance of the GFR markers iohexol, chromium-51-ethylenediaminetetraacetic acid (51Cr-EDTA), and inulin using 11 anephric pigs. METHODS: After an intravenous (i.v.) bolus injection of the markers, the decay curves of their plasma concentrations were monitored for 29 hr by 16 plasma samples. The area under the curve (AUC; concentration of marker versus time) was calculated according to one- and three-compartment kinetics. The extrarenal clearance was calculated by dividing the dose of marker by the AUC. RESULTS: In the three-compartment model, the median of the extrarenal clearances of iohexol, 51Cr-EDTA, and inulin were 0.87 ml.min-1.10 kg-1 (range = 0.62-1.26 ml.min-1.10 kg-1), 0.79 ml.min-1.10 kg-1 (range = 0.61-1.04 ml.min-1.10 kg-1), and 0.83 ml.min-1.10 kg-1 (range = 0.65-1.17 ml.min-1.10 kg-1). The extrarenal clearance of 51Cr-EDTA was slightly lower than that of iohexol and inulin when measured with the three-compartment model (p = .015). There was no statistically significant difference between the two models of kinetics in calculating clearance of the same marker. CONCLUSION: Our results indicate that subtracting the median values of the extrarenal clearance of the markers from the total plasma clearance will provide GFR values closer to the "true" GFR. This technique might prove useful in GFR calculations in patients with a very low GFR (e.g., residual GFR in patients on dialysis).

Animals↗
PubMed1996

Clearance of iohexol, chromium-51-ethylenediaminetetraacetic acid, and creatinine for determining the glomerular filtration rate in pigs with normal renal function: comparison of different clearance techniques.

RATIONALE AND OBJECTIVES: We wanted to improve determination of the glomerular filtration rate (GFR) with plasma clearance techniques because the alternative-renal clearance techniques-may involve inaccurate urine sampling or risk of urinary tract infection when bladder catheterization becomes necessary. Therefore, we compared the renal and plasma clearances of iohexol and chromium-51-ethylenediaminetetraacetic acid (51Cr-EDTA), as well as endogenous creatinine clearance, in 19 normal pigs using different techniques. METHODS: After an intravenous bolus injection of the GFR markers, 16 plasma samples were used to plot the marker concentrations versus time for 4.5 hr. Urine was collected during nine 30-min periods. Plasma clearance was calculated by dividing the dose of marker with the area under the plasma concentration curve (AUC) from the time of injection to infinity using one-compartment (ClAUC-slope) and three-compartment (ClAUC-3comp) models. The renal clearance was calculated by dividing the amount of marker excreted in the urine in a period with the AUC in the same period. This AUC was determined by integrating the total area in the period (Clren adv)--our reference method representing the "true" GFR--or by using the arithmetic mean of the plasma concentrations of the marker at the beginning and end of the urine collection period (Clren simple). Creatinine clearance was determined according to Clren simple. RESULTS: Renal clearances of iohexol and 51Cr-EDTA were significantly higher than creatinine clearance (P = .0002). There was no significant difference between the renal clearances of iohexol and 51Cr-EDTA or between their plasma clearances. The two mathematical methods of calculating the renal clearance of iohexol were highly correlated (rs = .99), as were the two methods of calculating its plasma clearance (rs = .95). Because of the extrarenal clearance of the markers, the plasma clearance methods for iohexol and 51Cr-EDTA always overestimated the true GFR. ClAUC-3comp was the method closest to the true GFR. For iohexol, the median overestimation of the GFR was higher with ClAUC-slope when early plasma samples (30-120 min) after injection of the marker were used (5.5 ml.min-1.10 kg-1) than when late samples (180-270 min) were used (4.0 ml.min-1.10 kg-1). After subtracting the median extrarenal clearances of iohexol and 51Cr-EDTA (previously determined in nephrectomized pigs) from their plasma clearances (ClAUC-3comp), the median overestimation of the true GFR was reduced from 2.0 to 1.1 ml.min-1.10 kg-1 with iohexol and from 2.1 to 1.3 ml.min-1.10 kg-1 with 51Cr-EDTA. CONCLUSION: GFR determination with plasma clearance techniques can be improved in three- and one-compartment models by taking late plasma samples and by subtracting the extrarenal plasma clearance of the species. One-compartment models can be improved by determining a correction formula in the species for the early parts of the decay curve of the plasma concentration of the marker.

Animals↗
PubMed1996

Image quality and safety after iodixanol in intravenous urography; a comparison with iohexol.

A double-blind, randomized phase III study compared intravenous urography in 100 adult patients receiving iodixanol 320 mgI ml-1 (Visipaque) with 99 patients receiving iohexol 350 mgI ml-1 (Omnipaque). The aim of the study was to investigate differences in image quality between a non-ionic dimeric contrast medium (CM) and a non-ionic monomer at 40 ml per patient and 60-100 ml per patient volume levels. There were no statistically significant differences between iodixanol and iohexol with respect to overall diagnostic information, which was found to be optimal in 86% and 79%, respectively. Immediately after the injection, the renal border was better delineated with iohexol than with iodixanol (p = 0.0001). Marked papillary blush occurred more often in the iodixanol group (16%) than in the iohexol group (0%), as did visualization of the collecting ducts (24% vs 5%) (p = 0.001). The incidence of adverse events was similar and low for both contrast media. In patients who received the higher doses of CM (60-100 ml), the frequency of discomfort was significantly lower after iodixanol than after iohexol (p = 0.006). We conclude that, in intravenous urography, iodixanol provides at least as good image quality as does iohexol. Iodixanol may cause less discomfort than iohexol, in particular when larger volumes of CM are injected.

Adult↗
PubMed1995

The physical performance of different x-ray contrast agents: calculations using a Monte Carlo model of the imaging chain.

A Monte Carlo computational model of the imaging chain has been used to investigate the performance of x-ray contrast agents with atomic number, Z, 53 < or = Z < or = 90 with respect to physical image quality descriptors (contrast and signal to noise ratio, SNR) and patient mean absorbed dose. Contrast agents of equal molar concentrations were used within a water slab (simulating the patient). The imaging conditions were chosen to represent adult and paediatric examinations. For all tube potentials studied (40-140 kV), the contrast agents with the highest atomic numbers (bismuth and thorium) gave the highest contrast. In analogue screen-film imaging, several other contrast agents could produce a higher image contrast than iodine in a limited range of tube potentials. This advantage could alternatively be effected as a reduced amount of administered contrast agent, or as a reduced mean absorbed dose in the patient. In digital imaging, a lower mean absorbed dose for a constant SNR than that with iodine can be achieved for ranges of tube potentials and contrast agents. Bismuth and thorium yield a lower dose than iodine at all studied tube potentials. Gadolinium and erbium could alternatively be used at a broad range of tube potentials above 90 kV with a dose penalty of only 5-20%.

Adult↗
PubMed1995

Sodium-calcium relationships and cardiac function during coronary bolus perfusion.

The present review deals with the side-effects of contrast media (CM) on cardiac function during coronary angiography. A physiological approach is used to redefine existing concepts of CM osmotoxicity and chemotoxicity in terms of osmolal, ionic and molecular effects. The main idea conveyed is that purely ionic effects are of central importance during and immediately following the transit of a brief coronary bolus. Ionic effects result largely from rapid transient washout of normal extracellular ions, but are also influenced by ions present in the CM. In particular, the calcium (Ca) and sodium (Na) ions controlling cardiac function are easily affected. The myocardial Na-Ca exchange, which is mainly a physiological mechanism for cellular Ca efflux during cardiac relaxation, is therefore highlighted in detail. The importance of avoiding a potential Na-Ca mismatch is shown by examples from basic physiology, cardiac surgery and coronary angiography and by results of experiments with Visipaque. In the isomolal and isotonic CM Visipaque, which is based on the dimer isodixanol (320 mg I/ml), an available osmolal space is filled with an appropriately balanced supplement consisting of NaCl (19mM) and CaCl2 (0.3 mM).

Animals↗
PubMed1995

Determination of the relative glomerular filtration rate of each kidney in man. Comparison between iohexol CT and 99mTc-DTPA scintigraphy.

Iohexol and 99mTc-DTPA were used in 43 patients to determine the relative glomerular filtration rate (GFR), i.e., the GFR of each kidney in percent of total GFR. The amount of any GFR marker accumulating in Bowman's space, tubuli and renal pelvis within a few minutes after i.v. injection, before any marker had left the kidney via the ureter, was defined as proportional to the GFR of that kidney. The renal accumulation of iohexol was determined by CT using 10 slices of 8-mm thickness 1 to 4 minutes after injection. The renal accumulation of 99mTc-DTPA was determined with a gamma camera within 2 minutes after injection. The correlation coefficient between the two methods was 0.98. Due to the higher radiation dose from CT than from 99mTc-DTPA injection, relative GFR determination with CT should be performed when there is also a diagnostic need to reveal morphology.

Adolescent↗
PubMed1995

The use of iohexol clearance to determine GFR in patients with severe chronic renal failure--a comparison between different clearance techniques.

UNLABELLED: The nonionic low-osmolar contrast medium iohexol was used as marker of glomerular filtration rate (GFR) in 53 patients with stable renal function (group I: n = 32, group II: n = 21). All the patients had clearance values < or = 30 ml.min-1.1.73 m-2 body surface; 40 patients < 20 ml.min-1.1.73 m-2 body surface. Simultaneous determinations of renal clearance and plasma clearance, both as slope clearance and single sample clearance, were performed after intravenous injection of 10 ml iohexol 300 mg iodine/ml. In groups I and II plasma was sampled early (around 3 hours) and late (up to 24 hours) after the injection. In group I urine was collected during four 40-minute periods and in group II during one 3-hour period and in group II the residual urine was estimated by ultrasound. Plasma and urine iodine concentrations were analyzed with X-ray fluorescence technique (Reanalyzer PRX90, Provalid AB, Sweden). In group II S-creatinine and tubular function test were followed to detect any signs of nephrotoxicity. In 6 anuric patients (group III) 10 ml iohexol 300 mg I/ml was injected to assess its extrarenal clearance. In groups I and II the slope clearance correlated excellently with the single sample clearance (r = 0.99) when a late plasma sample was used in both techniques. In group II, where residual urine was estimated by ultrasound, renal clearance correlated better with slope clearance than in group I (r = 0.94 vs r = 0.89). There were no signs of nephrotoxicity in the parameters noted. In group III, extrarenal plasma clearance of iohexol did not exceed 2 ml.min-1.1.73 m-2. CONCLUSION: GFR < 20 ml/min can accurately and safely be determined as renal clearance or plasma clearance of iohexol after an intravenous dose of 10 ml 300 mg I/ml. Plasma clearance techniques, which have the practical clinical advantage of no urine sampling, do at low GFR require a late plasma sample taken, for instance, 24 hours after injection of iohexol, irrespective of whether slope technique or single sample technique or one-compartment or poly-compartment models are used.

Adult↗
PubMed1995

Effects on erythrocyte aggregation and blood coagulation from iohexol solutions with and without sodium chloride. An in vitro study on the role of ion concentration and osmolality.

Solutions of the nonionic monomeric contrast medium iohexol (300 mg I/ml) with and without added NaCl were investigated for effects on red blood cell aggregation and blood coagulation. Three volumes of a test solution were mixed in test tubes with one volume of human blood. During 30 min samples of the mixture were taken for investigation. Six test solutions were used: 1) iohexol, 2) iohexol+glucose 280 mM, 3) iohexol+NaCl 150 mM, 4) glucose 280 mM, 5) glucose 140 mM+NaCl 75 mM, 6) NaCl 150 mM. Test solutions with NaCl caused no aggregation. Test solutions without NaCl always caused macroscopic red cell aggregates. These aggregates always disappeared when saline was added to the sample. The macroscopic red cell aggregates could be dispersed to microscopic aggregates by shaking the test tubes. During the next 30 min macroscopic aggregates returned in the glucose solution but not in the iohexol solutions. In 30 min, blood mixed with iohexol solutions never coagulated while blood layered on top of the same iohexol solutions always coagulated. Blood mixed with solutions 5 and 6, both without iohexol, always coagulated. It is concluded that adding 150 mM NaCl to iohexol did not eliminate its ability to anticoagulate whole blood, but inhibited its ability to aggregate red cells. This inhibition was not caused by the osmotic effects of the added NaCl.

Blood Coagulation↗