The impact of cognitive load on prefrontal cortical activity in surgeons during laparoscopic surgery

Introduction

Excessive mental workload can hinder surgical performance, but current methods for cognitive load assessment are subjective and post hoc. Functional near infrared spectroscopy (fNIRS) is a portable, non-invasive functional neuroimaging modality which has been used in non-surgical settings to show that greater mental workload increases activation in the prefrontal cortex (PFC). The aim of this feasibility study is to delineate the patterns of brain activation when surgeons are cognitively loaded.

Methods

Surgical trainees (n=5) were assessed during performance of laparoscopic suturing. Participants performed the task under two conditions: 1) in a self-paced manner and 2) under time pressure (order randomised). In both conditions, a 24-channel fNIRS system was used to determine task-induced changes in PFC activation. Technical performance was also recorded using objective measures.

Results

Laparoscopic suturing elicited a typical haemodynamic response in the PFC (Figure 1). In 2 subjects, there was no difference in PFC activation between the two conditions, whilst in 3 subjects there was a less marked PFC response during the time pressure condition (Figure 2). Inferior technical performance was observed in the time pressure condition (mean modified FLS score: 559.6 vs 522.5; mean progression score: 5.9 vs 4.2).

Conclusion

These preliminary findings suggest that some individuals exhibit less recruitment of their PFC when performing a laparoscopic task while cognitively loaded, and that this is coupled with a deterioration in performance. Although further work is required to clarify and understand these trends, fNIRS shows promise in online cognitive state monitoring in surgeons.

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Authors (in order):

Hemel N. Modi (corresponding author hemel.modi12@imperial.ac.uk 07733215000)

Harsimrat Singh

Daniel R. Leff

Guang-Zhong Yang

Ara Darzi

Figure 1. A typical haemodynamic response in the PFC during a laparoscopic suturing task. The grey block represents the task window.

Figure 2. Time course of average changes in haemoglobin parameters in the PFC for one participant during a laparoscopic suturing task performed self-paced (dotted line) and under time pressure (solid line). The grey block represents the task window.