Excitability in free muscle transfers: an optimal method of monitoring tissue circulation?

Abstract

Recent methods of postoperative monitoring of free muscle transfers were used in 4 patients operated on with free revascularized gracilis muscle. The contractility/electromyographic (EMG) activity in response to electrical stimulation was used as an index of viability, i.e., intact circulation. However, during operations it was observed that contractions as well as EMG potentials could be evoked 1 to 2 hours after blood flow had been arrested. Muscle excitability was further studied in the gracilis muscle from a patient who had undergone hemipelvectomy; it was found that contractility and EMG potentials were evoked at least 4 hours after circulatory arrest. It thus seems that loss of muscle excitability is not as early a sign of impaired blood supply as recently has been suggested. Spontaneous EMG activity, which can be recorded 2 to 3 weeks after denervation, is reported to be affected earlier than muscle excitability by circulatory arrest. Thus, the recording of spontaneous EMG activity in previously denervated muscles is proposed as an alternative and simple electrophysiological method for post-operative monitoring of vascularization in free muscle transfers.

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