The influence of interscalene block technique on adverse hemodynamic events

Abstract

A hemodynamic event such as hypertension after interscalene block (ISB) is a complication that is often overlooked. The irregular spread of local anesthetic would cause a blockade of carotid sinus baroreceptors leading to the adverse event. The purpose of the present study is to compare ultrasound and neurostimulation technique in preventing hypertension after ISB. Thirty patients without hypertension history who underwent arthroscopic shoulder surgery for a rotator cuff tear were enrolled. After preoperative administration of the State Trait Anxiety Inventory questionnaire, patients were allocated to receive ultrasound-guided ISB with 20ml levobupivacaine-HCl 0.5% (group US) and 40ml levobupivacaine-HCl 0.5% with neurostimulation (group NS). The need for antihypertensive drug was recorded. Block onset sensory and motor times were assessed. Systolic and diastolic blood pressures, and heart rate and pulse oximetry (SpO2), were evaluated before the block as well as 2, 5, 10, 15, 20, and 30min after. No differences in patient characteristics and anxiety were found in the two groups. Block onset times were similar. At 15min after block placement, group NS showed significantly higher systolic and diastolic blood pressures compared to group US. No differences in heart rate and SpO2 were found between the two groups. Three patients of group NS required urapidil administration because of hypertension. Ultrasound-guided ISB permits the use of a low volume of local anesthetic and seems to reduce the incidence of hypertension.