Hypotensive bradycardic events during shoulder arthroscopic surgery under interscalene brachial plexus blocks

Abstract

Sudden, profound hypotensive and bradycardic events (HBEs) have been reported in more than 20% of patients undergoing shoulder arthroscopy in the sitting position. Although HBEs may be associated with the adverse effects of interscalene brachial plexus block (ISBPB) in the sitting position, the underlying mechanisms responsible for HBEs during the course of shoulder surgery are not well understood. The basic mechanisms of HBEs may be associated with the underlying mechanisms responsible for vasovagal syncope, carotid sinus hypersensitivity or orthostatic syncope. In this review, we discussed the possible mechanisms of HBEs during shoulder arthroscopic surgery, in the sitting position, under ISBPB. In particular, we focused on the relationship between HBEs and various types of syncopal reactions, the relationship between HBEs and the Bezold-Jarisch reflex, and the new contributing factors for the occurrence of HBEs, such as stellate ganglion block or the intraoperative administration of intravenous fentanyl.

Changes in heart rate variability after sitting following interscalene block

“…Therefore, ISBPB appears to cause failure of the sympathovagal balance to shift toward sympathetic predominance after the patients transitions to the sitting position. Horner's syndrome, resulting from ipsilateral stellate ganglion blockade due to extended distribution of local anesthetics from the interscalene groove to the ipsilateral stellate ganglion, is thought to contribute to HBEs [2,25]. A recent abstract attributed the shift in the sympathovagal balance toward parasympathetic tone (decreased LF/HF) both in the supine and sitting position after ISBPB to ipsilateral stellate ganglion blockade [8].…”

Effect of interscalene brachial plexus block on heart rate variability

“…They observed that the total dose of epinephrine in the ISB was greater in patients experiencing BH while the patients who received systemic β-antagonist treatment were protected from these episodes. It has been postulated that endogenous as well as exogenous epinephrine, inducing a β-2 adrenergic effect, play a role similar to tilt-table testing in patients with unexplained syncope [9,16]. Further studies supported these hypotheses.…”

“…More recently, in 63 patients studied retrospectively with a 20.6% incidence of BH, the right operation side clearly favored the appearance of BH (R/L = 12/1 for the BH group vs R/L = 32/18 for the non-BH group) [7]. Recently, this relationship between BH and block side, with a contributing "intermediate" role of the ipsilateral stellate ganglion, is noted in a review addressing hypotensive and bradycardic events during ISB [9] and in an abstract of a prospective study implicating HRV analysis in ISB, where a significant percentage of patients showed Horner's syndrome signs [17]. Both, the review and the abstract were published after our decision to proceed with this study.…”

“…Conflicting data exist about the impact of the use of epinephrine as an additive to the local anesthetic solution [5,7]. As stellate ganglion block is frequently observed along with ISB [6], an association of this block with bradycardia and/or hypotension has been proposed [9]. Furthermore, this extension of the block, from brachial plexus to stellate ganglion, may explain the different incidence of cardiovascular instability between right and left-sided ISBs [2,7].…”

History of syncope predicts loss of consciousness after head trauma: Retrospective study

“…It is well known that injuries, both serious and minor, of other parts of the body than the head may provoke TLOC of reflex origin. Blood drawing, injection, piercing, and orthopedic arthroscopy have been reported to induce vasovagal syncope [4][5][6]. A tilt testing protocol involving subcutaneous insertion of a needle into the dorsum of hand after 10 min of passive tilt has been shown to have similar to conventional tilt protocols sensitivity and specificity [7].…”