Carbon dioxide digital subtraction angiography: the practical approach.

CO(2) has developed into a viable alternative to iodinated contrast for digital vascular imaging. Because CO(2) is a gas, it has a unique set of properties that affords certain advantages over iodinated contrast in a variety of settings. However, if CO(2) is used inappropriately, these same properties are associated with a unique set of rare but potentially harmful events. Therefore, it is essential that these unique characteristics be understood in order to employ a few simple precautionary measures. Fortunately, there is a delivery system currently available that is readily assembled and easy to use that ensures the appropriate administration of CO(2). This system, combined with experience, can reduce the greater labor intensity sometimes associated with CO(2) digital subtraction angiography. When it is used appropriately, CO(2) digital subtraction angiography alone or in combination with iodinated contrast offers diagnostic and interventional rewards that are not available with traditional intravascular contrast examinations.

Standardized measurement of the future liver remnant prior to extended liver resection: methodology and clinical associations.

BACKGROUND: There is no agreement regarding the preoperative measurement of liver volumes and the minimal safe size of the liver remnant after extended hepatectomy. METHODS: In 20 patients with hepatobiliary malignancy and no underlying chronic liver disease, volumetric measurements of the liver remnant (segments 2 and 3 +/- 1) were obtained before extended right lobectomy (right trisegmentectomy). The ratios of future liver remnant to total liver volume were calculated by using a formula based on body surface area. In 12 patients, response to preoperative right trisectoral portal vein embolization was evaluated. In 15 patients who underwent the planned resection, preoperative volumes were correlated with biochemical and clinical outcome parameters. RESULTS: The future liver remnants increased after portal vein embolization (26% versus 36%, P < .01). Smaller size liver remnants were associated with an increase in postoperative liver function tests (P < .05) and longer lengths of hospital stay (P < .02). Preliminary data indicates an increase in major complications for liver volumes < or = 25% (P = .02). CONCLUSIONS: A simple method of measurement provides an assessment of the liver remnant before resection. It is useful in evaluating response to portal vein embolization and in predicating the outcome before extended liver resections.

Internal jugular and upper extremity central venous access in interventional radiology: is a postprocedure chest radiograph necessary?

OBJECTIVE: The necessity of obtaining a postprocedure chest radiograph after central venous access using the upper extremity or internal jugular veins and interventional radiologic techniques was evaluated. SUBJECTS AND METHODS: A prospective study of 937 consecutive central venous access procedures in interventional radiology using the internal jugular veins or upper extremities was performed from June 1995 through September 1997. Established interventional radiologic techniques were used to place various ports (n = 34) and tunneled (n = 670) and nontunneled (n = 233) catheters. All catheters were positioned using fluoroscopy and readjusted if necessary before termination of the procedure. Afterward, a chest radiograph was obtained with the patient upright to evaluate catheter position and possible procedural complications. Procedural complications and manipulations or interventions that resulted from the radiographic findings were noted. In addition, nursing time for acquisition of the chest radiograph was recorded. RESULTS: We found seven procedural complications (four air emboli, two pneumothoraces, one innominate vein laceration) significant enough to alter the patient's treatment. These complications were apparent during the examination. Postprocedure chest radiography failed to reveal any unknown complications and revealed only one catheter sufficiently malpositioned to require manipulation. The amount of nursing time to acquire postprocedure chest radiographs ranged from 8 to 40 min (mean, 23 min) per patient. CONCLUSION: When imaging guidance and interventional radiologic techniques are used for upper extremity and internal jugular central venous access, performing postprocedure chest radiography yields little benefit.

CO2 digital subtraction angiography for renal artery angioplasty in high-risk patients.

OBJECTIVE: The efficacy of CO2 digital subtraction angiography for performing renal artery angioplasty in high-risk patients was evaluated. SUBJECTS AND METHODS: From January 1997 to July 1998, 21 high-risk patients underwent 29 renal artery angioplasties using carbon dioxide as the principal contrast agent. Six patients had a known allergy to iodinated contrast material and 15 had elevated levels of creatinine. Iodinated contrast material was used only if necessary. All periprocedural allergic reactions were recorded. Before and 24 hr after the procedure, serum creatinine levels were obtained. If the creatinine level had become significantly elevated (>0.5 mg/dl), the creatinine level was acquired a second time. RESULTS: Twenty-one patients (13 men and eight women) underwent 29 angioplasties (two were bilateral and six were repeated). Four kidney transplantation patients had ostial stenosis and the remaining 17 patients had nonostial stenosis. For all patients except one angioplasty initially was a technical success, as defined by a residual stenosis of less than 30%. Supplemental iodinated contrast material was used in only six patients (average dose, 8.5 ml). A range of 80-200 ml of carbon dioxide per procedure was used (average dose, 114.6 ml). One renal artery dissection occurred, which was unrelated to the carbon dioxide. There were no allergic reactions. The level of serum creatinine remained the same after 11 procedures, decreased after 12 procedures, and increased minimally after four procedures (<0.5 mg/dl). CONCLUSION: On the basis of our preliminary findings in a small group of patients, using carbon dioxide as an intravascular contrast agent to perform renal artery angioplasty in patients who have an allergy to iodinated contrast material or who suffer from renal insufficiency is safe and efficacious.

Comparison of hepatic damage from direct injections of iodinated contrast agents and carbon dioxide.

PURPOSE: This study guides the choice of contrast agent for localization of portal veins during transjugular intrahepatic portosystemic shunt (TIPS) placement or use in percutaneous transhepatic cholangiography (PTC) by providing gross anatomic and histologic comparison of effects from parenchymal injections of iodinated contrast agents and carbon dioxide. MATERIALS AND METHODS: Eighteen New Zealand White rabbits received direct injections of 2-5 mL of either the nonionic contrast agent iohexol 300 mgI or the ionic contrast agent diatrizoate meglumine 60% into one lobe of the liver and the same volume of CO2 into the other lobe. The rabbits were killed at 2-7 days for gross and histologic evaluation of the livers. RESULTS: At the time of injection, the diatrizoate and iohexol sites showed persistent dark discoloration, whereas CO2 sites showed minimal visible changes. On gross examination at death, all diatrizoate sites showed severe scarring and also commonly showed areas of necrosis. CO2 and iohexol sites showed only minimal discoloration and needle-puncture scars (P < .0001). The histologic grade for diatrizoate sites was significantly more severe than paired CO2 sites (P < .016). Iohexol sites showed mild histologic changes similar to paired CO2 sites (P = .375). CONCLUSION: Iohexol and CO2 produce less severe hepatic damage and are preferred to meglumine diatrizoate for hepatic injection.

Carbon dioxide digital subtraction angiography for renal artery stent placement.

PURPOSE: To determine the efficacy of renal artery stent placement with use of carbon dioxide as the primary contrast agent. MATERIALS AND METHODS: Seventeen hypertensive patients with renal ostial stenosis were evaluated and underwent stent placement with use of CO2 digital subtraction angiography (DSA). Besides hypertension, 11 patients had decreased renal function, three had iodinated contrast material allergy, one patient had both, and two had neither. Supplemental iodinated contrast material (25 mL or less) was used in five patients. Preprocedure and postprocedure serum creatinine levels were obtained to evaluate the effect of CO2 on renal function. Arteriography was used to evaluate stent positioning. RESULTS: Twenty-three Palmaz stents were placed in 17 patients. Six placements were bilateral, with a total of nine right and 14 left. No additional stents were required to correct malposition. One patient had a mildly significant, yet transient, rise in the postprocedure creatinine level. This patient received 10 mL of iodinated contrast material in addition to CO2. There were no allergic reactions. CONCLUSION: The utilization of CO2 DSA facilitates the accurate placement of renal artery stents by eliminating the concern for contrast material-associated nephropathy and allergy. These attributes, coupled with the benefit of low viscosity, permit unrestricted imaging, guidance, and precise positioning not afforded by iodinated contrast material.

Interventional radiology placement of twin Tesio catheters for dialysis access: review of 75 patients.

PURPOSE: To evaluate the safety and efficacy of modern interventional radiology techniques and imaging guidance for placement of jugular vein twin Tesio hemodialysis catheters. MATERIALS AND METHODS: Eighty-two sets (75 patients) of twin Tesio catheters were percutaneously placed in the right (n = 70) and left (n = 12) internal jugular veins with use of ultrasound (US) and fluoroscopic guidance. Immediate procedural and late complications were recorded. The efficacy of the Tesio system was also evaluated. RESULTS: With US and fluoroscopic guidance, the technical success for access and catheter placement was 100%. Measured dialysis blood flow rate of greater than 375 mL/min was obtained in 95% of the patients and recirculation averaged 4.6% +/- 5%. An inadvertent common carotid artery puncture occurred in one (0.6%) patient and prolonged exit site bleeding occurred in another five patients (3%). Each of these was successfully controlled with compression. More chronically, catheter thrombosis and exit site infection occurred each at the rate of 0.16 episodes per 100 catheter days. All thrombosis and exit site infections responded to local thrombolysis and antibiotic therapy, respectively. Bacteremia occurred in 20 patients and required catheter removal in five patients. There was no clinical evidence of upper extremity or superior central vein thrombosis. CONCLUSION: Placement of internal jugular, twin Tesio catheters with use of imaging and interventional techniques provides a safe and efficacious means of either short or long-term hemodialysis.

Sonographic guidance when using the right internal jugular vein for central vein access.

OBJECTIVE: The intent of this study was to substantiate the advantages of the use of sonographic guidance for central venous access via the right internal jugular vein. SUBJECTS AND METHODS: Eighty sequential patients requiring central vein access were examined with a hand-held sonography transducer to determine the size, patency, and location of the right internal jugular vein before puncture. Access to the right internal jugular vein was subsequently performed, under sterile conditions, using sonographic guidance. Periprocedural complications were prospectively recorded. Subsequently, we compared our findings with published reports of complications when visible and palpable anatomic landmarks were used for guidance during cannulation of the internal jugular vein. RESULTS: Among these 80 patients, the anatomy of the right internal jugular vein was typical in only 57 (71%). In another 13 patients (16%), sonography showed a medial position of the right internal jugular vein, anterior to the common carotid artery. In three other patients (4%), the right internal jugular vein was positioned laterally by more than 1 cm. In the remaining seven patients (9%), the vein was thrombosed. Its diameter, measured without use of the Valsalva maneuver, also varied, measuring 0.5-2.0 cm. Cannulation was achieved in all 73 patients with a patent right internal jugular vein. One puncture was required in 68 patients (93%); two punctures in three other patients (4%); and three punctures in the remaining two patients (3%). In no case was the common carotid artery inadvertently punctured. Only one periprocedural complication occurred, and it was unrelated to the use of sonographic guidance. CONCLUSION: Sonographic guidance for central vein access via the right internal jugular vein is safer and more efficient than the traditional landmark approach.

Angiography with carbon dioxide (CO2).

CO2 possesses many advantages over conventional iodinated contrast agents used for arteriography. It is nonallergic and lacks renal toxicity. Its unique properties permit use of smaller catheters in diagnostic and therapeutic angiographic procedures, allow optimal vascular imaging of various neoplasm, assist in detection of occult gastrointestinal bleeding, and facilitate TIPS procedures. With digital subtraction techniques and stacking programs, CO2 arteriography is as accurate as iodinated contrast studies in most patients and thus is the preferred arterial imaging technique in patients with contrast allergy and renal insufficiency. CO2 is also extremely inexpensive compared with available contrast agents. Understanding of the effects of buoyancy and compressibility is necessary for safe, controlled delivery of CO2 during arteriography, but only rare complications have occurred in our large experience with CO2 angiography. Thus, use of CO2 as an arterial contrast agent significantly expands the safety and utility of arterial imaging in patients with peripheral vascular disease.

Carbon dioxide (CO2) digital subtraction angiography: 26-year experience at the University of Florida.

Although the vascular system is presently being imaged by multiple high technology modalities, contrast angiography continues to be the gold standard; however, severe complications rarely occur. During the last 25 years (in over 1400 patients), CO2 has proven to be extremely safe (no allergy or renal failure). However, it is imperative to understand CO2's physical properties and potential dangers. Recently, CO2 is being routinely utilized not only because of safety, but for detection of minute amounts of bleeding, better collateral filling, and for most interventional procedures since unlimited volumes of CO2 can be injected between the catheter and guidewire. Presently, safe, reliable and "user-friendly" delivery systems are now commercially available. CO2 DSA images are now nearly comparable to iodinated contrast, and improvement in DSA images are evolving, including "stacking" software.

Examination of renal donors as outpatients using intraarterial digital subtraction angiography and a pigtail catheter.

OBJECTIVE: We performed this study to assess the safety and efficacy of outpatient angiographic renal donor examination using a 3-French pigtail catheter, intraarterial digital subtraction angiography, and a progressively shortened examination time after the procedure. CONCLUSION: For 45 consecutive procedures performed, no complications were reported, and no diagnostic discrepancies were found in patients who proceeded to surgery. Using this method we were also able to eliminate the excretory urogram as well as reduce the total amount of contrast per procedure.

Long-term performance and complications of the Tesio twin catheter system for hemodialysis access.

The Tesio twin catheter system (Medcomp, Harleysville, PA) was developed to overcome the problems with the existing central venous catheters in providing high-efficiency dialysis, such as inadequate blood flows, high recirculation rates, and need for surgical insertion. The relatively large internal lumens and multiple side holes in a spiral pattern allow for high blood flow rates and lower tendency to thrombosis. In this series, 82 catheter pairs were placed in 75 patients and monitored for a period encompassing 231 patient-months. We achieved mean nominal blood pump flow rates of 400 +/- 6 mL/min and an average recirculation of 4.6% +/- 0.5%. In 20 sets of catheters, a nominal blood flow rate of 388 +/- 6 mL/min was measured ultrasonically at 352 +/- 8 mL/min, representing an error of 36 +/- 5 mL/min. Thrombosis of the catheter occurred at a rate of one episode per 21 patient-months, and on all occasions responded to local instillation of urokinase. Despite having two exit sites, the infection rates were comparable to other catheters: exit site infections occurred at a rate of one per 21 patient-months and bacteremic episodes occurred at one per 11.5 patient-months, necessitating catheter removal once per 46 patient-months. Based on these data, we believe that the Tesio twin catheter system is an excellent long- and short-term vascular access for providing high-efficiency dialysis.

Button self-retaining drainage catheter.

To help improve patient acceptance of long-term internal/external catheter access to the biliary tract in those with benign biliary obstruction, a simple design allows the catheter end to remain flush with the skin. It consists of a clothes button affixed to the drainage catheter with a wood screw after the catheter has been cut off at the skin exit. This button/screw device has been used successfully in 22 patients over the last 10 years; catheter exchanges were easily accomplished.