Comparison of ultrasound-guided and nerve stimulator-guided interscalene blocks as a sole anesthesia in shoulder arthroscopic rotator cuff repair: A retrospective study.

Ultrasound-guided interscalene block (US-ISB) and nerve stimulator-guided interscalene block (NS-ISB) have both been commonly used for anesthesia in shoulder arthroscopic surgery.This study aims to compare which method provides surgical block as a sole anesthesia. In this retrospective study, 1158 patients who underwent shoulder arthroscopic rotator cuff tear repair surgery under ISB between October 2002 and March 2018 were classified into either the US-ISB or NS-ISB anesthesia groups. Demographic and anesthetic characteristics and intraoperative medications were analyzed after propensity score matching and compared between the 2 groups.There was a 0.5% rate of conversion to general anesthesia in the US-ISB group and a 6.7% rate in the NS-ISB group (P < .001). The volume of local anesthetics used for ISB was 29.7 ±â€Š8.9 mL in the US-ISB group versus 38.1 ±â€Š4.8 mL in the NS-ISB group (P < .001). The intraoperative use of analgesics and sedatives such as fentanyl, midazolam and propofol in combination was significantly lowered in the US-ISB group (P < .001).US-ISB is a more effective and safer approach for providing intense block to NS-ISB because it can decrease the incidence of conversion to general anesthesia and reduce the use of analgesics and sedatives during arthroscopic shoulder surgery.

Cardiac arrest in a patient with anterior fascicular block after administration of dexmedetomidine with spinal anesthesia: A case report.

BACKGROUND: Dexmedetomidine is a sedative and analgesic agent that is administered intravenously as an adjunct to spinal anesthesia. It does not suppress the respiratory system significantly, but has adverse effects on the cardiovascular system, for example, bradycardia and hypotension. We here report a patient who underwent cardiac arrest during spinal anesthesia after intravenous infusion of dexmedetomidine. METHODS: A 57-year-old woman with no significant medical history underwent spinal anesthesia for arthroscopic meniscus resection after rupturing the right knee meniscus. Preoperative electrocardiogram revealed sinus bradycardia (54 beats/min) and a left anterior fascicular block. Spinal anesthesia was performed with 11 mg of 0.5% heavy bupivacaine, and the upper level of sensory loss was at T6. Dexmedetomidine infusion was planned at a loading dose of 1.0 mcg kg min over 10 minutes, followed by 0.7 mcg kg min intravenously, as a sedative. Two minutes after dexmedetomidine injection, her heart rate decreased to 31 beats/min and asystole was observed within 10 seconds. RESULTS: After a few minutes of cardiopulmonary resuscitation, spontaneous circulation returned and surgery was completed under general anesthesia. The patient was discharged, and experienced no complications. CONCLUSION: Dexmedetomidine can decrease blood pressure and heart rate, and may cause asystole in some cases. We suggest that dexmedetomidine should be carefully administered under close observation when the parasympathetic nerve system is activated during spinal anesthesia.

Changes in heart rate variability after sitting following interscalene block.

PURPOSE: Hypotensive bradycardic events (HBEs) occur in 5-28% of patients undergoing arthroscopic shoulder surgery in the sitting position after an interscalene brachial plexus block (ISBPB). The objective of this study was to investigate the effects of the sitting position following ISBPB on heart rate variability (HRV). METHODS: In this prospective case-control study, we evaluated 64 patients undergoing arthroscopic shoulder surgery under ISBPB and 49 nonsurgical control subjects. HRV power spectral analysis parameters were measured (and natural log-transformed) before ISBPB and after changing to the sitting position. The patients experiencing HBEs were assigned to the HBE group, and the remaining patients were assigned to the non-HBE group. RESULTS: HBEs developed in 18 patients (28.1%). Changing from the supine position to the sitting position after ISBPB did not induce a significant increase in the natural log-transformed ratio of low-frequency to high-frequency power (lnLF/HF). A significant decrease in natural log-transformed high-frequency power (lnHF) was observed compared to the control group, who presented a significant increase in lnLF/HF and an insignificant change in lnHF. lnHF was found to be significantly higher in the HBE group compared to the non-HBE group. CONCLUSIONS: Sustained vagal activity with a failed shift in the sympathovagal balance toward sympathetic predominance in response to sitting after ISBPB is associated with the development of HBE.