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Dr. Bin Zheng

The editor of Sutures, the newsletter of the ÌìÑÄÉçÇø's Department of Surgery, interviewed Dr. Zheng about these findings.

Sutures: JAMA Surgery recently published a paper based on data from France examining the role of surgeons’ stress on postoperative complication rates (JAMA Surg. 2025;160(3):332–340. doi:10.1001/jamasurg.2024.6072). Dr. Zheng, could you share your thoughts on this study?
 
Dr. Zheng: Yes, this paper tackles an essential question, i.e., how a surgeon’s stress may impact surgical outcomes. In the study, the authors used a variable derived from heart rate data, called the low-frequency to high-frequency (LF:HF) ratio, to quantify surgeon stress. Patient outcomes included major surgical complications recorded intraoperatively or within 30 days, ICU stays due to organ failure, and 30-day mortality. After performing complex statistical analyses, they reported a surprising finding: higher surgeon stress levels were associated with better patient outcomes.

Sutures: Were you surprised by this conclusion?

Dr. Zheng: In our own research, we’ve repeatedly found that higher stress levels in the OR tend to degrade surgical performance. Working with a team of scientists, we recently reviewed the many intraoperative factors contributing to stress and recommended ways to mitigate them for the sake of patient safety. In that light, the conclusion from this JAMA Surgery study contradicts our findings.

Sutures: Why do you think there’s such a discrepancy? Is this a breakthrough or an outlier?

Dr. Zheng: That question was also on my mind as I read the paper. Several methodological issues stood out. Most notably, they measured the attending surgeon’s heart rate only during the first five minutes of surgery. We know that stress fluctuates throughout an operation, influenced by patient condition, task complexity, and unexpected challenges. A more representative assessment would involve monitoring over a longer time frame, or, at the very least, during a more intense part of the procedure, such as the middle or final stages. Using only the first five minutes seems unjustified.

Sutures: That’s a good point; stress tends to build during surgery, not start high and fade.

Dr. Zheng: Exactly. The method they used to assess stress is also questionable. In our work, we often use validated paper-based tools like NASA-TLX and its surgical adaptation, SURG-TLX. These instruments allow for post-procedure self-assessment of mental, physical, and temporal demands, task complexity, situational stress, and distractions. They are easy to administer and applicable to the entire surgical team, not just the lead surgeon. Other physiological signals, such as pupil dilation, skin conductivity, and respiration rate, are also commonly used. Each has pros and cons. Heart rate, the signal used in this study, can lack specificity and be slow to reflect changes in workload. That’s why multimodal approaches, combining physiological signals with subjective assessments, are increasingly recommended. It’s puzzling that the authors did not include any supplementary measures to strengthen the validity of their stress assessment.

Sutures: In your own research, what tools do you find most effective?

Dr. Zheng: We rely heavily on eye-tracking data. The eyes are windows into human mind. Eye behaviours change almost instantly in response to the change of mental demands. For those interested, there’s a growing body of literature exploring this.

Sutures: Beyond the timing and tools for measuring stress, did anything else concern you in the study design?

Dr. Zheng: Yes. What I found most problematic was the study’s conceptual leap, from measuring stress to drawing conclusions about patient complications, without considering the critical intermediary: surgical performance. The logical progression should be: stress affects performance, and performance affects patient outcomes. Unfortunately, the study included no direct metrics of surgical performance, such as speed, consistency, or error rates. They did report procedure time (incision to closure time in Table 1), but they missed the opportunity to analyze whether early stress levels correlated with operative time. If the stress level measured at the beginning of surgery doesn’t correlate with how the surgery is performed, it’s difficulty to image it can meaningfully predict complications. Even if their statistical model shows an association, we must question its real-world relevance.

Sutures: Given these issues, what’s your vision for an improved study on this topic, particularly within the context of U of A Surgery?

Dr. Zheng: Studying the connection between surgeon stress and patient outcomes is a valuable pursuit, fitting perfectly to the field of Human Factors in Surgery, which I’m deeply passionate about. I believe we’re well-positioned at U of A Surgery to lead such work.
For a more robust study, we’d want to include continuous or full-length monitoring of surgeon stress over entire course of surgery, use multiple bio-signal channels, and incorporate validated subjective instruments. Just as importantly, we’d collect surgeons’ performance data and link it to patient outcomes across various specialties. It will require significant time, coordination, and computational resources to process the volume of data, but it’s feasible. This kind of collaboration between basic scientists and clinical teams has real potential to drive meaningful improvements in surgical care.

Sutures: Thank you, Dr. Zheng. We look forward to seeing collaborative projects from your team that help advance this important line of research.

Links to papers (in past four years)
1. Wu Y, Zhang Y, Zheng B. Workload Assessment of Operators: Correlation Between NASA-TLX and Pupillary Responses. Applied Sciences. 2024; 14(24):11975.
2. Wu Y, Zhang Z, Zhang Y, Zheng B, Aghazadeh F. Pupil Response in Visual Tracking Tasks: The Impacts of Task Load, Familiarity, and Gaze Position. Sensors. 2024; 24(8):2545.
3. Zhang ZS, Wu Y, Zheng B. A Review of Cognitive Support Systems in the Operating Room. Surgical Innovation. 2024 Feb;31(1):111-122.
4. Lee A, Torkamani-Azar M, Zheng B, Bednarik R. Unpacking the Broad Landscape of Intraoperative Stressors for Clinical Personnel: A Mixed-Methods Systematic Review. Journal of Multidisciplinary Healthcare. 2023 Jul 17;16:1953-1977
5. Liu X, Zhang Y, Jiang X, Zheng B (2022) Human Eyes Move to the Target Earlier When Performing an Aiming Task with Increasing Difficulties, International Journal of Human-Computer Interaction, 39(6) 1341-1346;
6. Liu, X., Sanchez Perdomo, Y.P., Zheng, B. et al. (2022) When medical trainees encountering a performance difficulty: evidence from pupillary responses. BMC Medical Education 22, 191 (2022).
7. He W, Jiang X, Zheng B. Synchronization of Pupil Dilations Correlates With Team Performance in a Simulated Laparoscopic Team Coordination Task. Simulation in Healthcare. 2021 Dec 1;16(6):e206-e213.
8. Chainey J, Elomaa AP, O'Kelly CJ, Kim MJ, Bednarik R, Zheng B. Eye-Hand Coordination of Neurosurgeons: Evidence of Action-Related Fixation in Microsuturing. World Neurosurg. 2021 Nov;155:e196-e202.
9. Zheng B, Jiang X, Bednarik R, Atkins MS (2021) Action-related eye measures to assess surgical expertise, BJS Open 5(5) zrab068