Patient Safety Tip of the Week


March 10, 2009     Prolonged Surgical Duration and Time Awareness



Our interest was piqued by a recent article demonstrating a new IT technique for updating of times remaining in surgical cases (Dexter et al. 2009). The authors note that predicting the duration of an ongoing surgical procedure is not always straightforward. For example, most would think that a case booked for 2 hours and currently at 1.5 hours would have 0.5 hours remaining. Not so, according to the authors, and the actual amount differs by type of procedure and other variables.


It is a very interesting technique where complex mathematical formulas are applied to historical data about prior similar cases (by surgeon and procedure) if available, then updated in a running time fashion during the surgical case and incorporating physiologic monitored data to provide an estimate of the time remaining in the current case. Sometimes text messages to and from the anesthesiologists participating in the case may also supplement the estimates. The updated estimates are then available on the “whiteboards” in the OR suite or on the operating room IT system. The updated estimates are very valuable to a variety of perioperative “stakeholders” such as anesthesiologists, surgerons, the PACU, the holding area, the scheduling desk, etc.


The system is touted as a way to significantly improve OR efficiency. And certainly it could. It would provide more accurate estimates to help transition to subsequent OR cases or to facilitate scheduling of add-on cases and improve flow in post-surgical care areas.


But we are intrigued that such a system could have a significant patient safety impact as well. It should certainly help minimze the time a patient would spend in a “holding” area, where staff monitoring the patient may be less familiar with the intricacies of his/her medical problems than would the staff back on the floor the patient came from.


But we wonder whether there might be additional advantages. Prolonged surgery has many potential patient safety complications. Cases that last longer than anticipated are likely more complicated and, as such, expected to have more complications. However, some complications are likely a result of the excessive length of the procedure itself. The longer a surgical procedure is, the higher the risk of surgical site infection and DVT/pulmonary embolism. Other potential complications of prolonged surgery are hypothermia, fluid shifts, nerve compression injuries, compartment syndromes, and rhabdomyolysis. One would expect that some other potential complications of prolonged surgery might include retained foreign bodies and traction-related tissue injuries.


You’ve heard us say before that the OR team, during the surgical timeout or during the presurgical huddle, should discuss issues related to prolonged cases. For example, they should discuss whether intraoperative DVT prophylaxis should begin if the procedure lasts beyond a certain duration. Or discuss at what duration a repositioning of the patient (to avoid nerve compression, compartment syndrome, or rhabdomyolysis) might be wise.


So it could be very useful to use the updated estimate of time remaining to again trigger some discussion on the above issues. In addition to the DVT prophylaxis and repositioning issues, it might raise questions about the need to temporarily ease up on traction. It might direct attention to maintenance of the patient’s body temperature. In a very prolonged case it might raise questions about the need for further doses of prophylactic antibiotics.


Our experience is that most OR teams are not very “time aware”. As cases go on longer, foot traffic in and out of the OR increases, both as staff go on breaks or change shifts and as interruptions for questions, etc. begin to affect the surgeons and anesthesiologists. That increased foot traffic may be one factor that increases the likelihood of surgical site infections (Lynch et al. 2009). Long duration of surgery has long been known to be a factor associated with increased risk of surgical site infection. Particularly in academic/teaching facilities, better “time awareness” might suggest the need for a more senior surgeon to take over a case that is not progressing as smoothly as it should.


Unfortunately, these are mostly just ideas that make sense. We don’t like to provide you with a lot of patient safety ideas that make good sense but have not been based in evidence. We’ve seen too many unintended consequences when we implement “good ideas”. But this paper so wet our appetite that we decided to throw out these ideas in hopes that some of you may pick up on them and perhaps try to develop that evidence base.





Dexter F, Epstein RH, Lee JD, Ledolter J. Automatic Updating of Times Remaining in Surgical Cases Using Bayesian Analysis of Historical Case Duration Data and "Instant Messaging" Updates from Anesthesia Providers. Anesth Analg 2009; 108:929-940



Alterman I, Sidi A, Azamfirei L, Copotoiu S, Ezri T. Rhabdomyolysis: another complication after prolonged surgery. J Clin Anesth. 2007 Feb;19(1):64-6.


Lynch RJ, Englesbe MJ, Sturm L, et al. Measurement of Foot Traffic in the Operating Room: Implications for Infection Control. American Journal of Medical Quality 2009; 24: 45-52








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