Introduction: Contrast induced nephropathy is a major concern linked to use of iodinated contrast, and strategies for minimizing renal injury have been explored and incorporated into many laboratories that perform coronary angiography. Contrast limits, which denote a threshold below which there is no incremental increase in the risk of renal injury, have been described. Whether or not a priori acknowledgement of these limits as part of a pre-procedural "Time-Out" reduces contrast utilization has yet been established. In this study, we investigate the effect of verbalizing pre-angiography thresholds on contrast utilization and the associated clinical outcomes.
Methods: We retrospectively reviewed 5,265 cases of coronary angiography performed at The Ohio State University Wexner Medical Center between December 2013 and August 2016. Of the patients, 4,281 (mean age 63 ± 12 years) and 984 individuals (mean age 62 ± 12 years) were identified in the pre- and post- implementation phases of the contrast time-out, respectively. There were two primary endpoints: 1) the proportion of procedures that utilized an amount of contrast ≤ threshold, and 2) the median difference between amount of contrast utilized and the contrast threshold. Secondary outcomes incorporated indices of renal function, and included changes in creatinine levels, glomerular filtration rate, and chronic kidney disease stage.
Results: Compared to the pre-"Time-Out" group, the post-"Time-Out" group had a higher proportion of procedures with contrast dose ≤ stated contrast threshold (88% vs. 84%, p<0.002), and a lower amount of total contrast volume (88 mL [IQR 60-136] vs. 78 mL [IQR 53-119], p<0.001). Any increase in post-procedure creatinine was observed in 45% and 36% of individuals before and after the "Time-Out" protocol was implemented, respectively (p=0.04). Change in CKD stages did not differ significantly between the two groups.
Conclusion: Implementation of contrast "Time-Out" as part of cath lab protocol creates heightened awareness of contrast limits among physicians performing coronary angiography. This protocol is associated with reduced overall contrast utilization, and likely minimizes risks of contrast-induced renal dysfunction.