Tissue Oxygen Saturation Change on Upper Extremities After Ultrasound-Guided Infraclavicular Brachial Plexus Blockade; Prospective Observational Study

Abstract

Background and Objective: The aim of this study was to investigate whether tissue oxygen saturation (StO2) is a reliable and objective method for assessing the adequacy of infraclavicular block and to describe the time course of StO2 changes. Materials and Methods: In this prospective observational study, StO2 was measured in 40 patients planned for elective hand surgery under infraclavicular block. Noninvasive StO2 monitoring was used prior to ultrasound-guided infraclavicular brachial plexus block and during the first 30 min of the blockade. Sensory and motor blocks were evaluated every 5 min followed by pinprick testing and Bromage scale. Results: Preanesthetic median StO2 values of the blocked side and nonblocked side were similar (p = 0.532), whereas the postanesthetic values of the blocked side were higher. At the fifth minute and the following minute, measurements compared to the nonblocked side (p < 0.001). The median StO2 values increased significantly, which increased by 4.5% at 5 min, by another 5.5% at 30 min, and by an average of 1% from 5 to 30 min compared to the baseline values in the blocked side. The responses of the patients to the questions probed in the pinprick test and Bromage scale were fully compatible with the data obtained by the near-infrared spectroscopy (NIRS) method. Conclusions: StO2 monitoring may provide a useful instrument for rapid evaluation of the success of regional anesthesia in the upper extremity.

Keywords: infraclavicular block; near-infrared spectroscopy; regional anesthesia; tissue oxygen saturation; ultrasound.

Figure 1

Changes in tissue oxygen saturation within 30 min in 5 min intervals after initiation of infraclavicular brachial plexus block in blocked side and nonblocked side. StO2 increased from the fifth minute in blocked side (p < 0.05) when block was successful. There was no significant change in nonblocked side compared to blocked side from the fifth minute.