The prolongation of pulse transit time after a stellate ganglion block: An objective indicator of a successful block

BACKGROUND: An objective marker of successful stellate ganglion block (SGB) does not exist. Horner syndrome, which is currently used to determine the effect of SGB, is sometimes ambiguous. OBJECTIVE: To investigate the change in pulse transit time (PTT) after SGB, and to evaluate the utility of PTT as an objective measure of successful SGB. METHODS: Eight patients (34 to 62 years of age) underwent SGB for diagnosis or treatment of sympathetically mediated pain of the upper extremities. The success of the SGB was determined according to the presence of Horner syndrome. Electrocardiography, noninvasive blood pressure measurements and pulse oximetry were used to monitor all patients. PTT was measured using data saved on the WinDaq waveform browser. RESULTS: PTT was measured at baseline and 3 min, 5 min and 10 min after the injection of a local anesthetic. At 3 min after SGB, the mean (± SD) PTT was 624.6±20.5 ms. At 5 min after injection, the mean PTT was 630.8±17.5 ms. Prolonged PTT at 5 min was found to return to the baseline value at 10 min (613.6±14.7 ms). According to the Friedman test, the differences from baseline values were significant (P=0.008). CONCLUSION: Measurement of PTT at 5 min after local anesthetic injection can help to objectively determine the success of SGB.