Extravascular lung water: effects of intravenous ionic and non-ionic (lopamidol) contrast media during ischemia

Intravenous injections of ionic contrast media increase extravascular lung water in patients with elevated left atrial pressure, particularly in the presence of myocardial ischemia. The authors compared bolus injections of sodium methylglucamine diatrizoate and iopamidol on extravascular lung water at several levels of left atrial pressure in dogs. Methylglucamine increased lung water by a maximum of approximately 25-30% above baseline levels at low (less than 3 mm Hg), moderate (approximately equal to 15 mm Hg), and elevated left atrial pressures (greater than or equal to 25 mm Hg). At matched pressures, the peak change in lung water in the dogs given iopamidol was +4%, +7%, and +6%, respectively. In dogs with myocardial ischemia, the differences were even more pronounced (+45%, +60%, and +70%, respectively, for ionic media, and +7%, +12%, and +21% for iopamidol). The authors caution against using ionic contrast media in patients with left ventricular dysfunction, particularly associated with ischemia. In such cases, non-ionic media appear safer.     

Extravascular lung water: effects of using ionic contrast media at varying levels of left atrial pressure and during myocardial ischemia

Intravenous injections of ionic contrast media are widely used in the performance of radiographic techniques. The effects of ionic contrast media on lung water are unclear in the setting of elevated left atrial pressure, particularly in the presence of myocardial ischemia. In this study, we examined the effects of bolus injections of intravenous sodium meglumine diatrizoate (Renografin 76, 1 ml/kg, injected at 20 ml per second) on measures of extravascular lung water (EVLW) at several levels of left atrial pressure and in the presence of myocardial ischemia. Bolus injections of Renografin 76 produced significant increases in EVLW, with similar mean peak increases of approximately 26% EVLW at low (initial pressure less than 3 mm Hg), moderate (approximately 15 mm Hg), and elevated left atrial pressures (approximately 25 mm Hg). At matched pressures, the peak change in EVLW in the ischemic dogs was +45%, +60%, and +70%, respectively (all P less than .001 vs. the nonischemic dogs). Thus, use of intravenous ionic media precipitated acute transient increases in lung water, which were exaggerated by myocardial ischemia. While the effects were time limited in this experimental model, caution is advised in using intravenous ionic media in patients who have left ventricular dysfunction, particularly if underlying ischemia is present.     

Anticoagulant effects of nonionic versus ionic contrast media in angiography syringes

To determine whether nonionic contrast media present a clotting hazard when plastic or glass injection syringes are contaminated with aspirated blood, we evaluated two nonionic (iohexol and iopamidol) and two ionic (ioxaglate and diatrizoate) contrast agents. We used a blood:contrast media ratio of 2 mL:5 mL and ten normal donors, each studied at 10, 20, 30, and 60 minutes, a parallel study of clotting and fibrinopeptide A (FPA) generation in plastic tubes, and life table analysis to estimate more accurately donor-based early clotting probabilities. While ionic contrast media are stronger anticoagulants, both nonionic and ionic media retard clotting in plastic tubes, and clotting in plastic and glass angiography syringes in comparison to saline controls. A clotting probability of 1% for nonionic agents in plastic syringes was not reached until a time (mean +/- SD) of 21.5 +/- 3.2 minutes. This contrasts with a time of 8.7 +/- 2.5 minutes for saline control. With plastic syringes, no clotting at all was observed at 10 and 20 minutes with either class of agents. Neither class of agents hastened the generation of FPA. We found no evidence, therefore, that nonionic agents either cause clots or are procoagulant.     

The anticoagulant effects of ionic and nonionic low-osmolar contrast media in dogs.

RATIONALE AND OBJECTIVES. The anticoagulant effects of ionic and nonionic low-osmolar contrast media were evaluated in vivo. METHODS. The amount of clot deposited on guide wires placed in the femoral vessels of dogs was weighed 30 minutes after the injection of 2 mL/kg of different contrast media. Six dogs were examined after injection of ioxaglate (ioxaglate group), six after injection of iopamidol (iopamidol group), and five after injection of saline (saline group). RESULTS. The mean weights of clot deposited on the guide wires in dogs in the ioxaglate group, the iopamidol group, and saline group were 30.5, 63.1, and 74.2 mg, respectively. The mean weight of clot deposition on the guide wires in the ioxaglate group was significantly less than in the iopamidol and saline groups, whereas there was no statistical difference in the mean weight of clot deposition on the guide wires in the iopamidol and saline groups. CONCLUSIONS. Ioxaglate, a low-osmolar, ionic contrast medium, has a greater anticoagulant effect than a low-osmolar, nonionic contrast agent, such as iopamidol.     

离子型与非离子型对比剂的副反应处理

非离子型低渗对比剂虽然大大降低了对比剂的副反应的发生率，但仍有少数患者可发生严重反应。及时有一定的措施，也无可阻止副反应向严重甚至威胁生命的方向发展。因此做为放射医师及护理人员也建立必要的规章制度，以使放射科的每个人都能发挥有效的救护作用，及时处理对比剂副反应需要的知识与训练。     

Use of informed consent for ionic and nonionic contrast media.

The use of informed consent before intravenous administration of contrast material remains a controversial issue. It involves explaining the risks of intravenous contrast material and obtaining the patient's permission for its use. All physician groups who had billed Pennsylvania Blue Shield for at least three intravenous contrast material-enhanced procedures performed in 1989 were surveyed. Informed consent was obtained from at least some patients by about two-thirds of physician groups before using intravenous contrast material, regardless of whether it was ionic or nonionic. Nonradiologists were more likely to obtain informed consent before the use of ionic contrast material than radiologists. Regardless of specialty, practices associated with larger hospitals (greater than 250 beds), larger physician groups (greater than 10), or a university used informed consent less often than smaller physician groups or those associated with a smaller hospital or a private practice. Though results may be affected by regional variation or increased usage since previous surveys, the use of informed consent before the intravenous injection of contrast material is a common practice; it is obtained in the majority of patients.     

Comparison of nonionic and ionic contrast agents in the rabbit lung

The objective of this study was to determine the short- and long-term radiographic, physiologic and histologic changes elicited in the lung of rabbits following the aspiration of commonly used radiographic contrast agents. All agents used, including nonionic agents, caused radiographically evident pulmonary edema which cleared by 24 hours. The contrast materials with higher osmolality, viscosity, and iodine content elicited the greatest physiologic and pathologic changes. No differences were found between an ionic and a nonionic agent with similar viscosities and iodine content, despite a lower osmolality in the nonionic agent. No contrast agent is innocuous when introduced into the lung.     

Arterial bolus dynamics of ionic and nonionic contrast media in intravenous administration

A more favourable intraarterial pattern of bolus dynamics can be expected in DSA on applying nonionic contrast media via the intravenous route, as can be concluded from the results of numerous experimental studies on the different effects of ionic and nonionic contrast media on cardiovascular function. However, bolus measurements of ionic and nonionic contrast media in intraindividual comparison of 28 patients via serio-CT did not yield any significant difference. The influences of various factors on measurement results--quantities of contrast media, time and method of measurement--are discussed as possible causes of this discrepancy.     

Quality of urography and renal clearance of ionic and nonionic contrast media.

The authors evaluated whether urographic quality correlated with patient hydration and the level of their renal function, depending on whether they received ionic or nonionic contrast media. One hundred patients with normal serum creatinine levels were randomly assigned to receive intravenous urography with either an ionic high-osmolar or a nonionic low-osmolar contrast medium. Patient hydration was evaluated by measuring urine osmolality in a sample voided just before the examination. The plasma concentration of iodine was determined in a single blood sample drawn approximately 3 hours later. From these determinations the plasma clearance of contrast medium was calculated. The urograms were assessed blindly with regard to nephrographic and pyelographic opacification, as well as overall diagnostic quality. The clearance varied between 42 and 115 mL x minutes-1 x 1.73 m-2. No systematic correlation of practical significance was found between the clearances and the urogram quality. A high urinary osmolality before the examination tended to improve quality with both media. It is not possible to assess glomerular filtration rate from nephrographic and pyelographic opacification, or from overall quality of routine urograms in patients with normal serum creatinine levels.     

Extravascular lung water

Extravascular lung water (idQw _l) is measured in vivo from the difference in mean transit times, computed by extrapolating the dilution curves, of two indicators, one freely diffusible, the other confined to the intravascular space. Using ³H₂O it has been shown that idQw _l is smaller than the amount of extravascular water obtained from the difference between wet and dry lung weight (Qw _l). Extrapolation allows one to use dilution curves for a short time, i.e., up to onset of obvious recirculation. Clearing the dilution curves or recirculation by deconvolution extends the observation time, which then becomes limited by sampling duration rather than onset of recirculation. This procedure entails recording recirculating tracers in the pulmonary artery (PA). Dilutions of tracers at input in PA and output in a systemic artery must be related to each other as continuous time functions. This is accomplished by means of a convolution integral. Deconvolution yields the frequency function of water molecule transit time in the extravascular lung space, l(t). In dogs and men, in both normal and edematous lungs, l(t) exhibits a knee and a fairly long tail. Extravascular lung water computed from l(t), idcQw _l, agrees with Qw _l and correlates with data on the extravascular thermal volume of the lung and with radiographic findings of lung edema. A radiographic score of pulmonary edema may be used clinically to assess extravascular lung water in cardiac patients and in patients with adult respiratory distress syndrome.

     

Cytotoxic effects of ionic high-osmolar, nonionic monomeric, and nonionic iso-osmolar dimeric iodinated contrast media on renal tubular cells in vitro

PURPOSE: To compare the cytotoxic effects of dimeric and monomeric iodinated contrast media on renal tubular cells in vitro with regard to osmolality. MATERIALS AND METHODS: LLC-PK1 cells were incubated with ioxithalamate, ioversol, iomeprol-300, iomeprol-150, iodixanol, iotrolan, and hyperosmolar mannitol solutions for 1-24 hours at concentrations from 18.75 to 150 mg of iodine per milliliter. Cytotoxic effects were assessed with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Data were analyzed with one-way analysis of variance; post hoc tests were performed. RESULTS: At equal iodine concentrations, ioxithalamate showed stronger cytotoxic effects than did other contrast media (MTT conversion for ioxithalamate was 4% vs that for ioversol of 32%, that for iomeprol-300 of 34%, that for iodixanol of 40%, and that for iotrolan of 41% of undamaged control cells at 75 mg of iodine per milliliter, n = 61-90, P < .001); there was no significant difference between low-osmolar monomeric and iso-osmolar dimeric contrast media (P > .05). At equal molarity, dimeric contrast media induced significantly stronger cytotoxic effects than did low-osmolar monomeric contrast media (40% for iodixanol and 41% for iotrolan vs 64% for ioversol and 59% for iomeprol-300 at 98.5 mmol/L, n = 61-75, P < .001). At equimolar concentrations, both dimeric contrast media showed stronger cytotoxic effects than did iso-osmolar formulation of iomeprol-150 (51% for iodixanol and 50% for iotrolan vs 77% for iomeprol-150 at 98.5 mmol/L, n = 35-40, P < .001). Mannitol solutions induced weaker cytotoxic effects than did corresponding contrast media compounds (74% for mannitol-520 vs 34% for iomeprol-300 and 41% for mannitol-1860 vs 4% for ioxithalamate, P < .001). CONCLUSION: Besides hyperosmolality, direct cytotoxic effects of contrast media molecules contribute to their cytotoxic effects. Results of this study indicate that dimeric contrast media molecules have a greater potential for cytotoxic effects on proximal renal tubular cells in vitro than do monomeric contrast media molecules.     

Cardiac complications of intravenous digital angiography. Comparison of ionic and nonionic contrast media

The review of 1405 digital intravenous subtraction angiographies carried out in the period may 1982-february 1985 showed in about 2% of the cases cardiac symptoms, which arose during or after the examination. In the great majority of the cases the symptomatology was characterized by angina pectoris. In order to better understand these data and analysing the results of the literature, a trial has been performed in 100 patients who underwent DSA. They have been divided into two groups in which two different contrast media, ionic (sodium meglumine diatrizoate) and non ionic (iopamidol) have been randomly injected. A detailed cardiologic anamnesis has been collected and EKG has been performed before and after each injection with pre-established gaps. The results showed that the incidence of cardiac symptoms and EKG variations is lesser with the non ionic contrast medium: therefore this agent is to be preferred at least in patients at risk from cardiologic point of view.     

Changes in the fibrinolytic system during angiography with ionic and with nonionic contrast media

RATIONALE AND OBJECTIVES: The purpose of the study was to evaluate and compare changes in some parameters of the fibrinolytic system caused by the use of ionic and nonionic contrast media during angiography in certain groups of patients. MATERIALS AND METHODS: Angiographic diagnostic procedures were performed in 126 patients (male and female) clinically suspected of having kidney cancer (38 patients), arteriosclerotic occlusive disease of lower extremities (44 patients), or dissection of cerebral artery (44 patients). The control group included 12 patients with clinical symptoms of the disease in whom angiographic examination excluded the presence of cerebral artery dissection or kidney cancer. Patients were randomly assigned to receive either an ionic (diatrizoate sodium) or a nonionic (iopromide) contrast medium. Immediately before and 30 minutes after administration, venous blood samples were obtained to determine select parameters of the hemostatic system. RESULTS: There were no significant differences in the fibrinolytic parameters within the control group after contrast medium administration. The nonionic contrast medium (iopromide) caused a decrease in fibrinolytic activity in the patients, unlike the controls, which was particularly pronounced among the patients undergoing renal angiography. CONCLUSION: The use of contrast media in some groups of patients led to transient changes in the fibrinolytic system. These results indicate that ionic contrast media should be used during angiographic procedures in patients at increased risk for thrombotic complications.     

Effects of contrast media under systemic heparinization on blood coagulation and fibrinolytic system during angiocardiography--comparison of ionic and nonionic contrast media]

Nonionic contrast media are suggested to cause increased thromboembolism (in vivo), because of less inhibitory action on blood coagulation and platelet aggregation (in vitro) as compared with ionic contrast media. Therefore, to prevent thrombotic complication, we examined whether differences in blood coagulation and fibrinolytic system between the two groups received nonionic (iopamidol) and ionic (ioxaglate) contrast media are seen in vivo when 2,500 unit heparin is administered during angiocardiography. 20 patients undergoing routine angiocardiography were randomized to two groups of 10 patients each. Blood heparin concentration, activated partial thromboplastin time, prothrombin time, thrombin-antithrombin III complex (TAT), antithrombin III, fibrinogen, alpha 2-plasmin inhibitor plasmin complex, fibrinogen and fibrin degradation product were measured at four stages during the procedure: before and 5 min after 2,500 unit bolus heparin administration, 5 min after left ventriculography, and at the end of procedure. Systemic heparinization inhibited clot formation in the presence of nonionic contrast media. TAT generations were elevated before heparinization, after heparinization, however these generations were remarkably inhibited in both groups. No remarkable differences were noted at 40 +/- 14 min duration of procedure when these parameters were compared between the two groups. Since nonionic contrast media did not activate blood coagulation and fibrinolytic system with 2,500 unit heparin administration as compared with ionic contrast media, systemic heparinization was demonstrated to be effective in the prevention of thrombotic complication.