Operating room efficiency in emergency surgery depends on how preparation, anaesthesia and surgery are timed and coordinated. An analysis of emergency surgical activity at Chongqing Emergency Medical Center examined these relationships through three core durations and four related performance metrics. After data quality checks, more than 3,400 emergency cases were included. Rather than examining timings separately, the framework compared how operating room time was divided between surgical and non-surgical activity and how preparation related to the procedure itself. The results showed clear variation across the full emergency case mix. Caesarean sections also stood out as a useful subgroup for comparing workflow patterns by anaesthesia method and surgical level. Together, these findings show how time-based measures can give a more practical view of operating room performance than duration figures alone.
Measuring Time Across the Operating Room Pathway
The analysis focused on three time intervals. Surgery duration covered the period from the beginning to the completion of the procedure. Surgical preparation duration covered the work before incision, including room setup, patient preparation, team briefings and equipment readiness. Anaesthesia duration covered the period from the start of anaesthetic administration until the patient returned to consciousness. These intervals created a structured picture of how time was distributed during emergency surgical care.
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Four performance metrics were then used to compare these phases more directly. The surgery-to-anaesthesia ratio measured how much of the anaesthesia period was occupied by surgery itself. The anaesthesia-surgery difference measured the amount of non-surgical time spent in the operating room. The preparation-to-surgery ratio measured preparation time against procedure time, while the preparation-surgery difference measured the absolute gap between those two phases. Together, these indicators offered a more operational view of efficiency, showing where time was concentrated and where imbalances appeared across emergency workflows.
Variation Across Emergency Cases
The final sample included emergency cases across a broad mix of surgical grades and incision grades. Average durations showed that anaesthesia lasted longer than surgery, while preparation was shorter and more stable than the other two phases. Most surgery times fell within a relatively limited range, and the same applied to anaesthesia and preparation, although some cases were far longer than the rest. The longest surgery and anaesthesia durations were recorded in the same patient during open reduction of a patella fracture, while the longest preparation duration reached several hours.
Across the full sample, the mean surgery-to-anaesthesia ratio and the mean preparation-to-surgery ratio were both around 0.60. The mean difference between anaesthesia and surgery was just under 68 minutes, while the mean gap between preparation and surgery was just over 72 minutes. Preparation duration showed greater stability than the other timing measures. Correlation analysis also showed that the main indicators did not move together in a simple way. The relationship between the two difference measures was weak, while stronger links appeared between the surgery-to-anaesthesia ratio and the preparation-surgery difference, and a negative relationship appeared between the two ratio measures. These patterns indicate that each metric captured a different aspect of operating room performance.
Caesarean Sections Show Distinct Patterns
Caesarean sections accounted for about 7% of operating room activity and were analysed separately. In this subgroup, all three duration measures were lower than in the broader emergency sample. Mean surgery duration was under 80 minutes, mean anaesthesia duration was just over 127 minutes and mean preparation duration was slightly below the overall average. The mean surgery-to-anaesthesia ratio was 0.61, while the mean anaesthesia-surgery difference was just under 50 minutes. Overall, caesarean sections followed a shorter timing profile than the wider emergency case mix.
Differences also appeared when cases were grouped by anaesthesia method. Most used combined spinal-epidural anaesthesia, while a smaller group used epidural anaesthesia. The surgery-to-anaesthesia ratio was higher under epidural anaesthesia, while the anaesthesia-surgery difference was lower. The preparation-to-surgery ratio was higher under combined spinal-epidural anaesthesia, but the preparation-surgery difference was larger under epidural anaesthesia. Surgical levels II and III accounted for almost all caesarean section cases and added another layer of variation when examined alongside anaesthesia method. Significant differences emerged in anaesthesia duration, surgery duration and preparation-related timing, showing that workflow patterns within a single procedure type could still vary substantially.
Operating room performance in emergency surgery becomes clearer when preparation, anaesthesia and surgery are measured separately and then compared through structured ratios and differences. Across the full sample, preparation duration was more stable than the other main measures, while the performance indicators reflected different aspects of workflow rather than a single shared pattern. Caesarean sections followed a shorter overall timing profile and showed further variation linked to anaesthesia method and surgical level. These findings support the use of time-based process measures to identify variation within operating room workflows and to sharpen attention on where coordination and efficiency may be improved.
Source: BMC Medical Informatics and Decision Making
Image Credit: iStock
References:
Yu H, Yuan Y, Zhang Y et al. (2026) Operating room performance metrics of anesthesia and surgery duration: a descriptive analysis of emergency surgical cases. BMC Med Inform Decis Mak: In Press.
