Hypaque Sodium (Page 5 of 7)

Roentgenographic Technique

A preliminary scout film may be obtained before the intravenous injection. Excellent shadows can often be obtained immediately after administration of the radiopaque medium (within a five-minute period). If preliminary preparation has been carried out, the urinary organs are usually best visualized on films exposed 5, 10, or 15 minutes after intravenous injection. If a film of the bladder is required, it is generally taken 25 or 35 minutes after injection.

In patients with impaired renal function, the best shadows may not be obtainable until later (30 minutes or more) because of delayed excretion, and additional film may have to be exposed.

Most urologists and roentgenologists believe that compression immediately above the symphysis (obtained by application of a small hollow rubber ball about the size of a grapefruit or by the rolled bed sheet technique) assures adequate filling of the pelves and ureters, and hence is of great value. Although compression undoubtedly improves the urogram, it also seems to increase the possibility of pyelorenal backflow or reflux by raising the pressure within the urinary tract.

ANGIOGRAPHY

Precautions

Since serious neurologic complications, including quadriplegia, have occasionally been reported following spinal arteriography or selective injection of arterial trunks providing spinal artery branches (usually the thyrocervical, costocervical, subclavian, vertebral, bronchial, intercostal), great care is necessary to avoid entry of a large concentrated bolus of the medium. Thus, a “pilot” dose may establish correct position of the catheter tip. The concentration of the medium should not be over 60 percent. The carefully individualized dose is usually under 5 mL but preferably 3 mL to 4 mL and the number of repeat injections held to a minimum with appropriate intervals between injections. Pain or muscle spasm during the injection may require reevaluation of the procedure.

Angiography should be avoided whenever possible in patients with homocystinuria, because of the risk of inducing thrombosis and embolism.

CEREBRAL ANGIOGRAPHY

Indication

HYPAQUE meglumine 60 percent may be administered for visualization of the cerebral vessels. In as much as cerebral angiography is a highly specialized procedure requiring the use of special techniques, it is recommended that HYPAQUE meglumine 60 percent be used for this purpose only by persons skilled and experienced in carrying out the procedure.

Contraindication

Carotid angiography during the progressive period of a stroke should be avoided, particularly on the left side because of the increased risk of cerebral complications.

Precautions

See PRECAUTIONS—General. Patients in whom cerebral angiography is to be performed should be selected with care.

Although cerebral angiography has been considered contraindicated in patients who have recently experienced cerebral embolism or thrombosis (stroke syndrome), many experts now believe that the diagnostic value of the procedure, when employed early as an aid in locating lesions amenable to operation, outweighs any added risk to the patient. Furthermore, a small number of postangiographic fatalities have been reported, including progressive thrombosis already clinically evident before angiography, in which the procedure did not appear to play any direct role. Patients with severe cerebrovascular disease should be examined primarily by indirect methods of angiography.

In cerebral angiography, every precaution must be taken to prevent untoward reactions. Reactions may vary directly with the concentration of the substance, the amount used, the speed and frequency of injections, and the interval between injections.

In subarachnoid hemorrhage, angiography is expected to be hazardous. In migraine, the procedure can be hazardous because of ischemic complications, particularly if performed during or soon after an attack.

Adverse Reactions

See ADVERSE REACTIONS—General. With any contrast medium introduced into the cerebral vasculature, neurologic complications, including neuromuscular disorders, seizures, loss of consciousness, hemiplegia, unilateral dysesthesias, visual field defect, language disorders (aphasia), amnesia, and respiratory difficulties may occur, particularly when the extent of the intrinsic lesion is unknown. Such untoward reactions are for the most part temporary, although permanent visual field defects have been reported. Some investigators who are experienced in angiographic procedure emphasize the fact that they tend to occur after repeated injections or higher doses of the contrast medium. Other clinicians find that they occur most frequently in elderly patients. Inasmuch as the procedure itself is attended by technical difficulties regardless of the risk the patient presents (eg, mechanical catheter obstruction of the vertebral artery can cause transient blindness), the more experienced the radiologic team, the fewer the complications of any degree that are apt to arise.

Amaurosis can occur following carotid or especially selective vertebral arteriography. It is almost always transitory (4 to 48 hours).

Dosage and Administration

A dose of 8 mL to 12 mL injected at a rate not exceeding the normal flow in the carotid artery (about 5 mL per second) is suggested. The dose may be repeated as indicated; however, an increased risk attends each repeat injection. Children require a smaller dose in proportion to weight. Light anesthesia may be required in these procedures.

PERIPHERAL ARTERIOGRAPHY AND VENOGRAPHY

Indications

HYPAQUE meglumine 60 percent may be administered for peripheral arteriography and for venography.

Precautions

See PRECAUTIONS—General. Extreme caution is advised in considering peripheral arteriography in patients suspected of having thromboangiitis obliterans (Buergers disease) since any procedure (even insertion of a needle or catheter) may induce a severe arterial or venous spasm. Caution is also advisable in patients with severe ischemia associated with ascending infection.

Adverse Reactions

See ADVERSE REACTIONS—General. Soreness in extremities has also been reported.

Adverse reactions observed during peripheral arteriography may sometimes be due to arterial trauma during the procedure (ie, insertion of needle or catheter, subintimal injection, perforation) as well as to the hypertonicity or effect of the medium. Reported adverse reactions include transient arterial spasm, extravasation, hemorrhage, hematoma formation with tamponade, injury to nerves in close proximity to artery, thrombosis, dissecting aneurysm, arteriovenous fistula (eg, with accidental perforation of femoral artery and vein during the needing), and transient leg pain from contraction of calf muscles in femoral arteriography. Transient hypotension has been reported after intra-arterial (brachial) injection of the medium. Also, brachial plexus injury has been reported with axillary artery injections.

During venography in the presence of venous stasis, inflammatory changes and thrombosis may occur. Thrombosis is rare if the vein is irrigated following the injection.

Dosage and Administration

Diagnostic arteriograms may be obtained with 20 mL to 40 mL of HYPAQUE meglumine 60 percent introduced into the larger peripheral arteries by percutaneous or operative methods. Visualization of veins in the extremities may be accomplished with 10 mL to 20 mL.

DIRECT CHOLANGIOGRAPHY

Contraindication

Percutaneous transhepatic cholangiography is contraindicated in patients with coagulation defects and prolonged prothrombin times until normal, or near normal, coagulation is achieved (eg, with vitamin K).

Precautions

In the presence of acute pancreatitis, direct cholangiography, if necessary, should be employed with caution, injecting no more than 5 mL to 10 mL without undue pressure.

Percutaneous transhepatic cholangiography should only be attempted when compatible blood for potential transfusions is in readiness and emergency surgical measures are available. The patient should be carefully monitored for at least 24 hours to insure prompt detection of bile leakage and hemorrhage. Cholespastic premedication, as with morphine, should be avoided. Respiratory movements should be controlled during introduction of the needle.

Adverse Reactions

Adverse reactions may often be attributed to injection pressure or excessive volume of the medium, resulting in overdistention. Such pressure may produce a sensation of epigastric fullness, followed by moderate pain in the back or right upper abdominal quadrant, which will subside when injection is stopped.

Hepatobiliary reflux of the medium may cause a pancholangitis or hepatitis which is usually transitory. Retrograde spread of the infection may produce liver abscess or septicemia. Pancreatic duct reflux may cause a transitory increase in serum amylase for a period of 6 to 18 hours without ill effects. Rarely it may cause pancreatitis.

In percutaneous transhepatic cholangiography, some discomfort is common, but severe pain is unusual. Complications of the procedure are often serious and have been reported in four to six percent of patients. These reactions have included bile leakage and peritonitis, which are more likely to occur in patients with obstructions that cause unrelieved high biliary pressure. Bleeding (sometimes massive with exsanguination) may occur, especially in patients with clotting abnormalities. Blood-bile fistula, manifested by an early urogram (within 2 minutes) has been reported. Hypotension with fever and chills, as manifestations of septicemia, have occurred. Tension pneumothorax, cholangitis, and bacteremia have been reported.