Background and Aims Shoulder surgery is commonly performed in the beach chair position (BCP). However, it may cause hemodynamic instability, especially when general anesthesia (GA) with a preoperative interscalene brachial plexus block (ISB) is used. Moreover, Hypotension or Bradycardia episodes (HBE) occurring during the BCP may be associated with an increased risk of neurological complications. The objectives of this study were to investigate the incidence and characteristics of HBEs and their associated factors.
Methods The Institutional Review Board approved this study. We retrospectively reviewed the medical records of patients who underwent arthroscopic shoulder surgery under GA combined with ISB in the BCP between January 1, 2015, and July 31, 2022. HBEs, patient demographics, anesthetic, and surgical factors were collected and analyzed for their association with HBEs.
Results From the identified cohort of 660 patients, 482 (73%) experienced HBEs. The onset of HBEs mainly occurred earlier after patient positioning, as the mean time to the first hypotension and bradycardia episodes were 12.96 ± 18.21 minutes and 10.44 ± 13.13 minutes, respectively. Multivariable analysis showed that increasing age, female gender, and history of hypertension were associated with HBEs. In contrast, bispectral index (BIS) monitoring was associated with a lower risk of HBEs.
Multivariable logistic regression analysis for factors associated with hypotension or bradycardia episodes
The distribution of hypotension episodes onsets
The distribution of bradycardia episodes onsets
Conclusions Age, female gender, and history of hypertension were independent risk factors for HBEs. BIS monitoring, in contrast, was a protective factor. Despite the high incidence of HBEs, no patient in this study suffered from a neurological complication. Further study is required to ascertain the advantages of BIS monitoring during the beach chair position surgery.