Effect of interscalene block on intraocular pressure and ocular perfusion pressure

Abstract

BackgroundInterscalene block (ISB) is commonly associated with Horner’s syndrome due to spread of local anesthetic to the cervical sympathetic chain. Postganglionic neurons that originate from superior cervical ganglia form the sympathetic innervation of eye. Decrease in sympathetic tone may change intraocular pressure (IOP) and ocular perfusion pressure (OPP). The aim of the study was to investigate whether ISB affects IOP and/or OPP.MethodsThirty patients scheduled for ambulatory shoulder surgery under regional anesthesia with a single-shot ISB (15 mL 0.5% bupivacaine and 15 mL 2% lidocaine) were recruited. The IOP and OPP in both eyes, mean arterial pressure (MAP), heart rate (HR) and end-tidal CO2 (ETCO2) were measured before ISB and 5, 10, 20, 30 and 60 min after ISB in the beach-chair position.ResultsThe baseline IOP and OPP were similar in the blocked and unblocked sides (IOP 17.60 ± 1.69 and 17.40 ± 1.96 respectively p = 0.432; OPP 49.80 ± 8.20 and 50 ± 8.07 respectively p = 0.432). The IOP in the blocked side significantly decreased between 10th to 60th min following ISB, compared to the baseline values (p < 0.001). The OPP in the blocked side significantly increased from 10th to 60th min (p < 0.001) whereas, there were no significant changes in IOP and OPP throughout the measurement period in the unblocked side.ConclusionsISB decreased IOP in the blocked side. ISB could be considered as a safe regional technique of choice in elderly patients at high risk for developing glaucoma.

Adverse heart rate responses during beach-chair position for shoulder surgeries - A systematic review and meta-analysis of their incidence, interpretations and associations

“…Sensitivity analysis revealed that various anaesthetic agents significantly influenced fall in HRs. However, it made little difference to the overall results when study controls[ 29 30 33 34 35 37 39 40 41 42 43 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 ] and randomised trials[ 4 6 12 13 15 16 26 27 28 29 30 33 34 35 37 38 39 41 42 44 45 46 47 50 55 60 61 64 ] were analysed separately [ Table 2 ]. Meta-regression was performed since primary outcomes, characterised by significant heterogeneity, yielded statistically significant omnibus P values for statistical models considering different maintenance agents and opioids.…”

“…With regard to EHR,[ 6 15 16 29 33 34 35 37 38 39 40 42 43 44 45 46 47 49 51 52 54 55 56 57 58 65 ] MHR[ 16 29 33 34 35 36 38 41 43 46 48 49 50 51 53 54 55 56 57 58 59 60 61 62 63 64 66 ] and DHR[ 6 16 29 30 38 43 46 47 49 51 55 56 60 65 ] responses, meta-analysis showed a statistically significant fall in HR in subjects with GA (GA or GA + RA, P < 0.0001). Sensitivity analysis and meta-regressions confirmed that fentanyl significantly influenced the HR drop over time (meta-regression, estimates, 14.8, 9.8 and 16.9; standard error (SE) 5.3, 4.3 and 2.8; P = 0.007, 0.024 and <0.001; for early, mid and delayed periods, respectively) in GA subjects (Omnibus P < 0.001.…”

“…BP responses were analysed from 67 SGs. [ 4 6 12 13 15 16 28 29 30 31 32 33 34 35 36 37 38 40 41 44 45 46 49 50 51 52 53 54 55 56 60 61 64 66 ] Seven subjects were excluded from the primary study[ 16 46 58 66 ] even before surgery due to severe hypotension after BCP. For treatment of hypotension, ephedrine,[ 4 6 12 13 16 28 32 35 36 44 45 49 52 60 ] phenylephrine[ 53 56 60 62 66 ] or combination of both[ 29 39 40 41 42 46 48 54 59 61 63 65 ] were used.…”

Assessment of the changes in cardiac sympathetic nervous activity using the pupil size changes measured in seated patients whose stellate ganglion is blocked by interscalene brachial plexus block

“…The ISBPB-induced reduction in pupil size (miosis is one of the clinical signs of Horner's syndrome) is attributed to the blockade of the stellate ganglion, to which local anesthetic placed around the brachial plexus spreads from the interscalene groove along the prevertebral fascia [3].…”

Repeatability, reproducibility, and agreement of three tonometers for measuring intraocular pressure in rabbits

“…Biomechanical factors may also affect IOP readings, such as corneal thickness and stiffness 8 – 10 , mental stress 11 – 14 , circadian rhythm 15 , 16 , and the type of (e.g. general) anesthesia or sedation 17 – 21 . The use of sedatives is common practice in animal studies and clinical procedures 22 , but the effect of injectable sedatives on IOP has not been fully characterized.…”