Elizabeth Gleeson, MD, MPH, Hasan Ayaz, PhD, Lucian Panait, MD, Andres Castellanos, MD, Catalin Copaescu, MD, PhD, Victor Tomulescu, MD, PhD. Drexel University College of Medicine, Dept of Surgery, Philadelphia, PA, Drexel University, School of Biomedical Engineering, Philadelphia, PA, Ponderas Hospital, Dept of Surgery, Bucharest, Romania, Fundeni Clinical Institute, Bucharest, Romania.
1. Introduction
Although assessment of cognitive load in human performance and learning has been used in military and civilian settings, its use in surgery lacks validation. Functional Near-Infrared Spectroscopy (fNIR) is a potential tool for these measurements. Cortical hemodynamic response in anterior prefrontal cortex has been shown to be a valid measure of task induced mental load. The objective of this pilot study is to determine construct validity for fNIR spectroscopy measurement of cognitive load during laparoscopic task performance.
2. Methods
Functional Near-Infrared Spectroscopy is a safe, non-invasive and portable optical neuroimaging technology that can be used to monitor hemodynamic changes that occur in the prefrontal cortex, i.e., oxyhemoglobin and deoxyhemoglobin concentrations and changes in blood volume. The mobile fNIR system used in the study is composed of three modules: a flexible sensor pad, which holds light sources and detectors for four optodes; a battery operated and miniaturized control box; and a computer that runs the data acquisition.
Ten general surgery attending physicians with basic laparoscopic skills underwent evaluation of cognitive load during performance of easy and complex laparoscopic tasks using standard laparoscopic instrumentation in an inanimate box trainer. The easy task consisted of touching four corners of a square with laparoscopic graspers while alternating hands. The complex task entailed tying a simple laparoscopic knot. Each task was repeated three times. Prefontal cortex oxygenation changes for each participant during easy and complex task performances were compared using repeated measures ANOVA.
3. Results
Overall, participants’ average prefrontal cortex oxygenation was higher while performing the complex task compared with the easy one. A statistically significant difference due to task difficulty was found in left hemisphere (F1,9=7.86, p< 0.05) in the optode gaining information from the frontal polar area 1 (Fp1 in the International 10–20 System for electroencephalogram electrode placement). These results compare favorably with previous neuroimaging findings of mental workload assessment such as air traffic controllers in which execution of more difficult task appears to induce additional effort and hence higher oxygenation compared with easier/control tasks.
4. Conclusions
To our knowledge, this is the first use of fNIR to assess cortical hemodynamic responses in surgeons. The study validates the use of fNIR in assessing cognitive load in laparoscopy and expands its use to laparoscopic training and education.
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