The effect of operating time on surgeons' muscular fatigue.

INTRODUCTION: A study was completed to determine if operating has an effect on a surgeon's muscular fatigue. SUBJECTS AND METHODS: Six head and neck surgery consultants, two ENT registrars, 20 normal controls from two tertiary referral centres in the West Midlands participated in the study. Electromyography (EMG) measurements were taken throughout a day of operating and fatigue indices were compared to controls performing desk work. RESULTS: The percentage changes in mean frequency of muscular contractions were examined; there was no significant difference in fatigue levels between consultants and registrars. Operating led to an increase in fatigue in all subjects, compared to no increase in controls performing desk work. It was also found that the brachioradialis muscle is used more than the mid-deltoid muscle and, hence, fatigues at a faster rate. CONCLUSIONS: Surgeons should be aware that their muscular fatigue levels will increase as an operation progresses; therefore, if possible, more complex parts of the operation should be performed as early as possible, or, in the case of a very long operation, a change in surgeon may be necessary.

Determination of muscle fatigue using dynamically embedded signals.

This paper explores a new method of analysing muscle fatigue within the muscles predominantly used during microsurgery. The captured electromyographic (EMG) data retrieved from these muscles are analysed for any defining patterns relating to muscle fatigue. The analysis consists of dynamically embedding the EMG signals from a single muscle channel into an embedded matrix. The muscle fatigue is determined by defining its entropy characterized by the singular values of the dynamically embedded (DE) matrix. The paper compares this new method with the traditional method of using mean frequency shifts in the EMG signal's power spectral density. Linear regressions are fitted to the results from both methods, and the coefficients of variation of both their slope and point of intercept are determined. It is shown that the complexity method is slightly more robust in that the coefficient of variation for the DE method has lower variability than the conventional method of mean frequency analysis.

Time dependency assessment of muscular fatigue index and hand tremor under operating conditions.

The aim of this paper is to determine if operating has an effect on a surgeon's muscular fatigue and hand tremor. Electromyography and tremor measurements were taken throughout a day of operating from the brachioradialis (BR) and mid deltoid (MD) muscles of six head and neck surgery consultants and two Ear, Nose, and Throat (ENT) registrars. The percent change in Mean Frequency (MF) of their EMG signal and tremor amplitudes was compared to twenty normal controls performing desk work. It was found that operating led to an increase in the fatigue level and hand tremor in all subjects, compared to very little increase from within the controls study. It was also determined that the BR is used more than the MD muscle and hence fatigues at a faster rate. Surgeons should be aware that their muscular fatigue levels and consequently their hand tremor will increase as an operation progresses, therefore, if possible, more complex parts of the operation should be performed as early as possible.