Contrast Medium Iohexol Research Articles

Biochemical evidence for a relative lack of inhibition of thrombin formation by nonionic contrast media.

An in vitro study was done to investigate the thrombogenic potential of nonionic contrast media. Whole blood from 18 healthy volunteers was mixed with ionic contrast medium (diatrizoate, ioxaglate), a non-ionic contrast medium (iohexol), or saline (the control) and incubated in glass and plastic test tubes. Levels of prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin III complex (TAT), and antithrombin III (AT III) were measured. Evidence showed increased thrombin formation in glass tubes compared with that in plastic tubes, a finding in concordance with the known association between contact with glass and increased activation of coagulation. F1 + 2 and TAT levels were significantly increased in the nonionic mixtures compared with such levels in ionic mixtures (P less than or equal to .05). Control mixtures showed little or no overall increased thrombin formation by F1 + 2 and TAT levels compared with nonionic mixtures. These findings suggest an inhibition of thrombin generation by ionic contrast media in vitro and a relative lack of such inhibition by iohexol.

Effect of an Iso-Osmolar Contrast Medium on Pulmonary Arterial Pressure at Pulmonary Angiography

A clinical comparison of the effects on pulmonary arterial pressure induced by contrast media with various osmolalities, iohexol 140 mg I/ml (300 mosm/kg H2O), iohexol 300 mg I/ml (690 mosm/kg H2O), and diatrizoate 292 mg I/ml (1480 mosm/kg H2O) following selective pulmonary angiography was made in 12 patients with normal pulmonary arterial pressure. A double-blind crossover study was performed and the contrast media were administered in random order. The pulmonary arterial pressure was recorded continuously before, during, and for 3 min after the injection. The effect of iohexol 140 on the pulmonary arterial pressure was significantly less marked than that of diatrizoate 292, whereas no statistical significance was shown between iohexol 140 and iohexol 300. These results indicate that iso-osmolar contrast medium (iohexol 140), as well as iohexol 300, would be better tolerated than diatrizoate 292, and is therefore a safer contrast medium for selective pulmonary angiography.

The clearance of iohexol as a measure of the glomerular filtration rate in children with chronic renal failure

The plasma clearances of technetium-99m-labelled DTPA ([99Tcm]-DTPA) and the non-ionic contrast medium iohexol were estimated in 11 children with chronic renal failure for determination of the glomerular filtration rate (GFR). Equal values were obtained with the two substances provided plasma sampling was simultaneous, but when plasma was sampled within 3.5 h after injection of iohexol and [99Tcm]-DTPA the GFR was overestimated by more than 50%. For clearance values below 20 ml min-1 1.73 m-2, valid GFR estimates were obtained both from two plasma samples taken 3 h and 24 h after the injection of iohexol and from a single plasma sample taken 24 h after the injection.

A single plasma sample method for estimation of the glomerular filtration rate in infants and children using iohexol, I: establishment of a body weight-related formula for the distribution volume of iohexol

This study was performed in order to develop a method for estimation of the glomerular filtration rate (GFR) from a single plasma sample based upon the plasma disappearance rate of the non-ionic contrast medium iohexol. The apparent distribution volume for iohexol was measured in 100 infants and children and used for establishment of a weight-related empirical formula for the distribution volume. Using the distribution volume obtained by this formula, a preliminary GFR was calculated from the iodine concentration measured in a plasma sample taken 3 h after injection of iohexol. When this estimate was corrected by another empirically established correction factor, a high degree of agreement was found between a GFR reference method and the 3-h single plasma sample method. In another group of 13 children the 3-h single plasma sample GFR was estimated twice with a 2-day interval, and the day-to-day variations were found to be similar to those obtained with other standard methods.

A single plasma sample method for estimation of the glomerular filtration rate in infants and children using iohexol, II: establishment of the optimal plasma sampling time and a comparison with the99Tcm-DTPA method

The glomerular filtration rate (GFR) can be determined from the plasma disappearance rate of the non-ionic contrast medium iohexol. A preceding study established the empirical formulae enabling the development of a single plasma sample method for estimation of GFR in infants and children. In the present study the validity of these empirical formulae was confirmed in examinations in 143 patients. The results of the single plasma sample method were similar to those of a standard 99Tcm-DTPA method, and also with those of a two plasma sample iohexol method. Evaluation of the results obtained with plasma sampling 1 h, 2 h, 3 h and 4 h after the injection of the contrast medium showed that the optimal sampling time was about 3 h after the injection.

Sodium Addition and/or Oxygen Saturation of Iohexol during Normal and Reduced Perfusion Pressure

The influence on contractile force (CF) and the propensity for ventricular fibrillation (VF) from infusing the non-ionic contrast medium iohexol during normal (75 cm H2O) and reduced perfusion pressure (35 cm H2O) were investigated in the isolated rabbit heart. Both during normal and reduced perfusion pressure iohexol (150 mg I/ml) with oxygen saturation caused a smaller reduction of CF than iohexol without oxygen. During reduced pressure iohexol with sodium addition (28 mM NaCl) caused less depression of CF than iohexol without sodium. The combination of sodium addition and oxygen saturation had the least influence on CF. Iohexol (350 mg I/ml) without sodium had a similar fibrillatory propensity during both normal and reduced pressure. Enriching iohexol with 28 mM NaCl decreased the risk of VF. The decrease was similar during both normal and reduced pressure. The risk of VF from oxygen saturation of iohexol (350 mg I/ml, without sodium) was similar during both normal and reduced pressure. It is concluded...

Sodium Addition and/or Oxygen Saturation of Iohexol during Normal and Reduced Perfusion Pressure

The influence on contractile force (CF) and the propensity for ventricular fibrillation (VF) from infusing the non-ionic contrast medium iohexol during normal (75 cm H2O) and reduced perfusion pressure (35 cm H2O) were investigated in the isolated rabbit heart. Both during normal and reduced perfusion pressure iohexol (150 mg I/ml) with oxygen saturation caused a smaller reduction of CF than iohexol without oxygen. During reduced pressure iohexol with sodium addition (28 mM NaCl) caused less depression of CF than iohexol without sodium. The combination of sodium addition and oxygen saturation had the least influence on CF. Iohexol (350 mg I/ml) without sodium had a similar fibrillatory propensity during both normal and reduced pressure. Enriching iohexol with 28 mM NaCl decreased the risk of VF. The decrease was similar during both normal and reduced pressure. The risk of VF from oxygen saturation of iohexol (350 mg I/ml, without sodium) was similar during both normal and reduced pressure. It is concluded that a small addition of sodium and/or oxygen saturation of a non-ionic monomeric contrast medium have beneficial effects on the heart both during normal perfusion pressure and during ischemia.

Effect on Thrombus Growth and Thrombolysis of Two Types of Low Osmolar Contrast Media in Rabbits

Thromboembolic complications have been reported after diagnostic or interventional radiological procedures. However, contrast media inhibit platelet function and blood coagulation in vitro. To investigate these characteristics in vivo, we determined the effect of nonionic and ionic low osmolar contrast media on thrombus growth and thrombolysis in rabbits in a randomized study design. Rabbits received either ionic low osmolar contrast medium (ioxaglate), nonionic low osmolar contrast medium (iohexol) or saline. Thrombus growth was determined by the accretion of 125I-labeled fibrinogen on to autologous, nonradioactive, preformed thrombi in rabbit jugular veins. Thrombolysis was assessed by measurement of the decrease in radioactivity of standard sized preformed 125I-fibrinogen labeled thrombi. Ioxaglate significantly inhibited thrombus growth (60% inhibition, P less than 0.005 vs. saline), in contrast to iohexol, which had no significant effect (33% inhibition, P less than 0.2 vs. saline). Neither ioxaglate nor iohexol affected thrombolysis.

Low Dose Intravenous Urography: Results and Technique Modifications

100 consecutive patients routinely referred for intravenous urography were examined using low doses of the low osmolar contrast medium Iohexol (Omnipaque 350mgl/ml). Their dosage schedule was based on the physiological parameters of age, sex, body weight and renal function. Comparison with a control group using standard contrast doses revealed a 42% reduction in contrast could be used, and still produce diagnostic studies. Nephrographic quality was reduced in the low dose group requiring technique modification, in particular a delayed film sequence. Further reductions in contrast use are envisaged in patients over the age of 40 years.

Effects on Renal Hemodynamics and Tubular Function of the Contrast Medium Iohexol in Renal Patients

Renal function was assessed in 20 (11 female and 9 male, age 21-76 years, mean 53) renal patients with a creatinine clearance 25-145 ml/min, mean 95, to evaluate the effects of iohexol, a non-ionic low-osmolar contrast medium. Intravenous urography was performed in 16 patients and computed body tomography in 4, using a dose of iohexol ranged between 0.6-3.3 (mean 1.17) g/kg b.w. Different parameters of renal function were determined in the week preceding and 1, 3 and 5 days after the administration of iohexol. The principal renal effect of iohexol was an increase of urinary alanine aminopeptidase, gamma-glutamyltransferase, lactate dehydrogenase, alkaline phosphatase and N-acetyl-beta-D-glucosaminidase. The maximum increase of enzymuria was observed on day 1 after the administration of iohexol. In most cases enzymes returned to base-line values within 3 days. No relevant variation of renal hemodynamics (glomerular filtration rate and effective renal plasma flow) was observed after iohexol. In conclusion, iohexol can increase of urinary enzymes, but the effect is rapidly reversible and is not accompanied by a clinically significant impairment of renal hemodynamics.

Glomerular filtration rate estimated by X-ray fluorescence technique in children: comparison between the plasma disappearance of99Tcm-DTPA and iohexol after urography

The total plasma disappearance of the non-ionic contrast medium iohexol was determined by X-ray fluorescence technique following intravenous urography in 10 children aged between 2 and 13 years. For comparison the plasma disappearance of 99Tcm-DTPA was estimated both 2 days before and simultaneously with the iohexol study. High correlations between the three sets of data were found and no change in the glomerular filtration rate was detected following injection of contrast medium. It was also found that reliable estimates of the glomerular filtration rate can be obtained from two plasma samples of 1 ml each, taken 3 h and 4 h after the injection of the contrast medium.

Effect of Sodium Addition to Non-Ionic Contrast Media on Cardiac Contractile Force

Cardiac contractile force after adding NaCl to the non-ionic contrast media iohexol and iopentol was investigated in the isolated rabbit heart. Iodine concentrations of 150, 300 and 350 mg I/ml were used with sodium concentrations ranging from 0 to 154 mmol/l. From physiologic experiences of nutrient solutions it should follow that a sodium-free solution of a non-ionic contrast medium, which also has the lowest hypertonicity, should cause the smallest decrease in contractile force. However, a small amount of sodium added to the contrast medium solutions, in the range of 19.25 to 38.5 mmol/l, caused the least decrease in contractile force. The decrease in contractile force was significantly more pronounced when no sodium was added or when larger amounts of sodium were added. A small amount of sodium also decreases the risk of ventricular fibrillation. Thus there is a possibility that addition of sodium could reduce the adverse effects of cardioangiography.

Effect of Sodium Addition to Non-Ionic Contrast Media on Cardiac Contractile Force

Cardiac contractile force after adding NaCl to the non-ionic contrast media iohexol and iopentol was investigated in the isolated rabbit heart. Iodine concentrations of 150, 300 and 350 mg I/ml were used with sodium concentrations ranging from 0 to 154 mmol/l. From physiologic experiences of nutrient solutions it should follow that a sodium-free solution of a non-ionic contrast medium, which also has the lowest hypertonicity, should cause the smallest decrease in contractile force. However, a small amount of sodium added to the contrast medium solutions, in the range of 19.25 to 38.5 mmol/l, caused the least decrease in contractile force. The decrease in contractile force was significantly more pronounced when no sodium was added or when larger amounts of sodium were added. A small amount of sodium also decreases the risk of ventricular fibrillation. Thus there is a possibility that addition of sodium could reduce the adverse effects of cardioangiography.

Changes in Atrial Natriuretic Peptide Concentration at Femoral Arteriography in Man

The changes in plasma concentrations of atrial natriuretic peptide were investigated in 10 patients who were examined for peripheral vessel disease by aorto-femoral angiography. All patients received 6 x 40 ml contrast medium (iohexol, 300 mg I/ml) plus an initial test dose of 15 ml, resulting in a total mean dose of 255 ml injected into the abdominal aorta. The contrast medium injections produced a significant increase in plasma atrial natriuretic peptide concentration (p less than 0.02). Furthermore a significant decrease was seen in systolic blood pressure (p less than 0.04). It is concluded that the plasma concentration of atrial natriuretic peptide increases after intraarterial injection of contrast medium, and that atrial natriuretic peptide might play a role in the hemodynamic changes seen after intravascular injections of contrast medium.

Cardiovascular response during cerebral angiography under general and local anaesthesia

Nineteen patients with subarachnoid haemorrhage who had cerebral angiography with the new contrast medium iohexol, were randomly allocated to receive either local anaesthesia plus sedation, or general anaesthesia. Arterial blood pressure, PaO2, PaCO2 and patient acceptability were examined. Significant fluctuations in arterial blood pressure occurred in the patients who received general anaesthesia. Local anaesthesia was associated with a stable blood blood pressure, adequate spontaneous ventilation and good patient acceptability. The quality of films obtained was examined and found to be of good or very good diagnostic quality in all cases in both groups of patients. Greater use of local anaesthesia with sedation for angiography is recommended.

The reaction of cerebral arteries to non-ionic contrast media during cerebral angiography.

The purpose of this study was to evaluate possible vasoconstrictive or vasodilatator effects of the low osmolar non-ionic contrast medium iohexol (Omnipaque) on the calibre of cerebral arteries. The diameters of respectively 5 and 6 different locations of the vertebral and carotid arteries were recorded from angiograms of 3 successive injections. The material consisted of 18 patients. It could not be shown that Omnipaque induced vasoconstriction or vasodilatation when normal doses and adequate technique was applied. The difference in diameters found were not statistically significant and are probably due to natural pulsations and to the difficulties in performing exact measurements.

Reduction of the Risk of Ventricular Fibrillation in the Isolated Rabbit Heart by Small Additions of Electrolytes to Non-Ionic Monomeric Contrast Media

Perfusion of the isolated rabbit heart with solutions (350 mg I/ml) of the non-ionic contrast media iohexol and iopentol, both containing NaCl (20 mmol/l), caused a significantly lower frequency of ventricular fibrillation (VF) than solutions without NaCl. Iohexol or iopentol with NaCl (10 mmol/l) caused an intermediate frequency of VF. Iohexol with 10 or 20 mmol NaCl/l caused about the same frequency of VF as iohexol solutions with about the same total electrolyte concentration but with electrolyte composition as that of Krebs' solution. At 320 mg I/ml, solutions of iohexol (20 mmol NaCl/l), iodixanol (20 mmol NaCl/l) and ioxaglate (155 mmol Na/l) all produced a significantly lower frequency of VF than iohexol without NaCl. Ioxaglate caused the largest and iodixanol the smallest decrease in contractile force of the media. The investigation suggests that the small risk of VF from non-ionic monomeric media can be further reduced by adding a small amount of sodium chloride or of the electrolytes of Krebs' solution.

Normal collecting ducts: visualization at urography.

In 21 of 636 patients with normal renal function and without obstruction of the upper urinary tract, urograms showed that contrast medium filled thin cylindrical structures in the renal pyramids with the same course as that of the collecting ducts. The prevalence of cylinders when the low-osmolality contrast medium iohexol was used was 21 of 158 studies (13.3%) and with the high-osmolality contrast medium amidotrizoate, two of 529 studies (0.4%). The cylinders were more distinct and more numerous with iohexol, while with amidotrizoate most cylinders appeared as striations. The cylinders appeared within 4 minutes from the start of contrast medium injection and remained distinct for 35-50 minutes. The diameter of the cylinders varied between 0.05 and 0.30 mm; their course was almost straight and closely followed the shape of the pyramid. The cylinders proved to consist of the highly opacified collecting duct lumina. Their configuration indicated that a single cylinder might be an individual collecting duct, but conclusive evidence was lacking.

Erythrocyte aggregation in iohexol and other nonionic media.

Erythrocytes aggregate when blood comes into contact with solutions of nonionic substances such as glucose or the contrast medium iohexol, especially at a reduced pH (eg, 6.8). The aggregates are not clots because they form rapidly even in heparinized blood, do not contain fibrin, and disappear at once when they are added to plasma or other ionic media. Formation of these aggregates in solutions of glucose or iohexol can be decreased by including a low concentration of an ionic solute such as NaCl or by maintaining the pH close to 7.4.

Spread of radiopaque dye in the thoracic epidural space

A radiological study was performed in 23 patients to look for the position of thoracic epidural catheters and the spread of the contrast medium iohexol 300 mg/ml and 180 mg/ml when used in volumes of 3 and 8 ml. The dye was injected through the epidural catheter just after thoracic surgery. The spread of the dye showed no relation to the injected volume or the sensory spread after 2% lignocaine 3 ml. In three cases no contrast could be seen on the x-ray, and in two the radiopaque dye was found just outside the epidural space. No relationship between the spread of the dye and the sensory blockade was found, but the position of the epidural catheter should be checked radiographically when the epidural route is to be used for long-term pain relief.