A prospective study of heart rate variability in endocrine surgery: surgical training increases consultant's mental strain.

Background: The aim of this study was to determine whether instructing surgical trainees in technically demanding procedures causes alterations in heart rate variability (HRV) and mental strain in supervising surgeons.
Methods: A prospective study of HRV in two consultant surgeons and three endocrine surgical fellows undertaking 50 total thyroidectomy procedures was performed. Fellows and consultant surgeons performed 50 lobectomies as primary operator and 50 as assistants in a cross-over design. HRV was measured during dissection around the recurrent laryngeal nerve. The overall heart rate, time, and frequency domain parameters of HRV, specifically the low frequency/high frequency (LF/HF) ratio, which was used as a measure of cardiac and mental stress, were correlated with the surgical role, particularly teaching surgical fellows at critical points.
Results: HRV data were collected between October 2009 and March 2010. There was no statistically significant difference in the mean heart rate for either group of participants regardless of role. Energy expenditure was greater for fellows when operating (p = 0.03). Fellows demonstrated a higher LF/HF ratio when acting as the primary operator (p = 0.02). All time domain parameters of HRV increased when attending surgeons were operating, denoting more cardiac relaxation. Similarly, the LF/HF ratio was significantly greater for attending surgeons when teaching (p = 0.05), suggesting an increase in mental strain.
Conclusions: The teaching of complex but common endocrine surgical procedures is associated with a measurable increase in mental strain of consultant surgeons, as determined by HRV. Fellows demonstrated increased levels of stress when acting as primary operators.
(Copyright © 2012 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.)