Complication Rates in Anesthesia.

Abstract

There are relatively few large studies describing perioperative complications in children. In this issue Gleich et al. describe the complication rates after perioperative arterial cannulation in children. In this single-center retrospective study, data were reviewed for all children aged less than 18 yr receiving anesthesia between 2006 and 2016. A total of 5,142 cannulations were performed in 4,178 children. Two-thirds of the cannulations were radial, and about 30% were femoral. There were 11 major complications, all when the femoral artery was cannulated and all in children less than 5 yr of age. Eight of the major complications were vascular, and three were infectious. The vast majority of femoral cannulations were for cardiac procedures. The data would imply that radial cannulation is a relatively safe procedure in children. It might also be inferred that femoral cannulation has a small but relatively high risk of complication, especially in younger children. These data are perhaps not surprising, because complications after femoral artery cannulation have been described before in several small studies where the artery had been cannulated for a variety of reasons. A strength of this study is its size. There are, however, some interesting limitations. The first limitation is that it is single center. Hospitals tend to follow particular practice patterns. At this center there was an unusually high rate of femoral cannulation, which may reflect their high cardiac surgery case load and their preference for femoral cannulation in this particular patient population. This may limit generalizability of their data. The other limitations relate to the retrospective nature of the study. Retrospective studies rely on accurate data entry and coding. Although positive cases can usually be verified by closer inspection of the record, such retrospective studies almost inevitably miss some cases. The true rate of complications was probably higher than that described in the article. The other limitation of retrospective studies is more subtle and particularly applies to rare events, such as complications. Why did the authors do the study? In the introduction they indicate that they did the study “based on clinical observational of several complications related to femoral lines.” In other words, they suspected there was a problem, so they went back and systematically examined the data; and sure enough, they found a high complication rate in femoral lines when compared with radial lines. These data are valid, but are they generalizable? Let’s assume a bunch of hospitals are similar in terms of patient load and anesthesia work practice. If complications are multifactorial, which they often are, we would expect the number of complications to vary randomly across hospitals. Some centers will have more of one type of complication simply owing to chance. Complications in pediatric anesthesia are generally rare and usually examined carefully in morbidity meetings or some form of quality process. A string of complications would attract attention. This could trigger a more detailed review, as happened in this case. So was the string of femoral line complications attributable to randomness, and this center was just unlucky, or did they uncover a fundamental issue with the technique that would be applicable to all centers? In such a single-center retrospective study there is no way of knowing. The fact that the authors looked because they had a suspicion might imply a random cluster of complications had triggered their “The ideal way to quantify complications is through prospective multicenter registries with clearly defined a priori queries that capture complications.”