TEACHING COLLECTION

Early Ambulation Strategies with Contrast Management

Michael J. Lim
Michael J. Lim
Efficiency in the cardiac catheterization lab is tied directly to patient recovery time in many institutions due to the limited recovery space and expenses inherent in the personnel required. This must always be balanced against the quality of care provided for the patients within the lab. Useful surrogates that may indicate high-quality care within the cardiac catheterization lab can include a low rate of post-procedural complications (especially vascular), high-quality angiographic images that allow for diagnostic accuracy, and a low total contrast volume per case in order to prevent contrast-induced nephropathy. One potential system that can be employed to improve quality and efficiency in the catheterization lab is the combination of smaller French (Fr) catheters and the the Angiographic Contrast Injection System Technology (ACIST) system (Acist Medical Systems, Eden Prairie, Minnesota). The complication rates of catheterization remains low. In a study looking at almost 8,000 diagnostic catheterizations over a 40-month period, the vascular complication rate was 1%.1 About half of the complications required surgical repair, and the most likely complications were the incidence of hematoma (0.9%) or pseudoaneurysm (0.1%). Diagnostic procedures on 5,046 patients and 1,866 interventional procedures were evaluated from another center, and the vascular complication rates were found to be 0.7% and 3.7%, respectively.3 The performance of coronary intervention was associated with a significantly higher rate of local hemorrhage and pseudoaneurysm compared to a group of patients who underwent diagnostic catheterization only. A recent report from a single center confirmed the higher incidence of local complications in those patients undergoing coronary interventions, which are primarily manifested by a higher transfusion rate (Table 1).3 In an attempt to understand the factors that are associated with complications following coronary angiography, Ammann et al4 evaluated 7,412 consecutive diagnostic catheterization procedures. There was an overall 0.8% complication rate in this patient cohort. Catheter size greater than 6 Fr and increased body weight were identified as the significant risk factors for the development of any major complication or vascular complications. When all of these studies are taken into account, catheter size rises to the forefront of controllable factors associated with vascular complications. Examining the historical trend of catheter sizes reveals that there has been a strong movement toward decreasing French size. In 1990, 8 Fr catheters were primarily used. In 1993 and 1992, 6 Fr catheter use started to take over, and in 1999, 4 Fr and 5 Fr catheter use became the norm and continues today. These smaller sized catheters are also accompanied by a decreased post-procedural period of bedrest and monitoring, making them extremely attractive options. A study of 101 patients tested the 4 Fr versus 6 Fr system for diagnostic angiography.5 All studies were performed via the femoral approach, with a targeted ambulation time of 90 minutes. The study found that 4 Fr catheters reduced compression time in the holding area by 36%. Ambulation time was not different, but that was by design of the protocol. However, the operator trades shorter ambulation times and potentially decreased vascular complications for lower angiographic quality when utilizing 4 Fr catheters. This concern centers around the difficulty in manually injecting contrast through the narrow-lumen 4 Fr catheter. Assessing 4 Fr angiography with manual versus ACIST power injection angiography showed that adequate visualization of the coronary arteries could be achieved with the ACIST system with a significant reduction in overall contrast volume utilized.6 A separate study of 1,114 patients undergoing diagnostic coronary angiography by experienced operators, randomized to 4 Fr to 5 Fr systems,7 showed that the image quality was similar between the smaller and larger catheters. Fluoroscopic time was also similar, but there was a significant increase in difficulty maneuvering the 4 Fr catheters. Many operators have had similar experiences with the 4 Fr catheters, which has decreased the overall enthusiasm for their use in routine angiography. Closure Device Early ambulation strategies can also utilize routine closure device placement in all patients. Many closure devices are available for the femoral artery and all of them allow patients to ambulate more rapidly than if manual arterial compression were utilized for sheath removal. However, it remains unclear whether this type of utilization subjects patients to a higher complication rate. Two recent studies have combined several smaller observational studies that look at routine use of closure devices and whether they increase or decrease complications. One study8 pooled 30 other studies which all had relatively poor methodology and included many different closure devices (Angioseal, Vasoseal, Perclose). This study found that closure devices were associated with an increased rate of hematoma, bleeding, A-V fistulas, and pseudoaneurysms. The hazard ratios for each of these endpoints favored manual compression over a closure device. In a separate meta-analysis, Nikolsky et al pooled 37,066 patients and looked at differences between closure device use and manual compression.9 Like the previous study, the odds ratio for vascular access-related complications favored manual compression (1.3, 0.90 to 1.87; p = 0.19). Therefore, one cannot assume that routine use of closure devices will decrease vascular complication rates. Contrast-induced Nephropathy The other complication that deserves attention is that of contrast-induced nephropathy. Despite its relatively low occurrence rate (0.8% of all catheterizations), operators should be concerned with its prevention because the mortality rate can be as high as 36%. Freeman et al clearly have shown that the incidence of contrast-induced nephropathy is proportionate to the amount of contrast administered.10 The ACIST system has the ability to track the total amount of contrast delivered to the patient in real time, and this amount is displayed for the operator. The system is also capable of delivering less contrast by changing the injection volume and/or the rate of injection for particular pictures. In this way, the ACIST system allows the operator to deliver only the amount of contrast needed for the given procedure. In the study by Khoukaz et al,5 4 Fr ACIST procedures utilized less contrast for ventriculography (32 versus 37 cc; p Conclusion. There is a paucity of data on which to rely in our efforts to improve the quality of care and catheterization lab efficiency. Unlike many areas of cardiology today, there are no large randomized clinical trials that demonstrate the most effective way to manage a catheterization lab and/or how to best administer contrast for coronary angiography. Thus, we must extrapolate from the available data and make individual decisions. Reducing the size of catheters is clearly something that has been universally accepted. Coupling a significant reduction in catheter size with the ACIST power injection system offers equivalent angiographic quality and significant reductions in contrast volume use, making it a combination warranting consideration. (This article is a CME offering in the Journal and is underwritten through an educational grant from Bracco Diagnostics)
References
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