Effects of Local Anesthetic Volume (Standard Versus Low) on Incidence of Hemidiaphragmatic Paralysis and Analgesic Quality for Ultrasound-Guided Superior Trunk Block After Arthroscopic Shoulder Surgery.

BACKGROUND: Relative to interscalene block, superior trunk block (STB) provides comparable analgesia and a reduced risk of hemidiaphragmatic paralysis. However, the incidence of hemidiaphragmatic paralysis remains high when a standard volume (15 mL) of local anesthetic is used. This study aimed to evaluate the effects of local anesthetic volume of STB on the incidence of phrenic nerve palsy, as well as its analgesic efficacy following arthroscopic shoulder surgery. METHODS: Patients scheduled for elective arthroscopic shoulder surgery were randomized to receive ultrasound-guided STB using either 5- or 15-mL 0.5% ropivacaine before general anesthesia. The primary outcome was the incidence of hemidiaphragmatic paralysis at 30 minutes after block. The secondary outcomes were pulmonary function, grade of sensory and motor blockade, pain score, opioid consumption, adverse effects, and satisfaction. RESULTS: Relative to standard-volume STB, low-volume STB was associated with a lower incidence of hemidiaphragmatic paralysis after block (14.3 [4.8%-30.3%] vs 65.7 [46.8%-80.9%]; difference 51.4% [95% confidence intervals {CIs}, 29.0%-67.1%]; P < .0001) and at the postanesthesia care unit (9.4% vs 50.0%; difference 40.6 [95% CI, 18.9%-57.7%]; P = .0004). Pulmonary function was also better preserved in the low-volume group than in the standard-volume group. The extent of the sensory and motor blocks was significantly different between the groups. Pain-related outcomes, satisfaction, and any adverse events were not significantly different between the groups. CONCLUSIONS: Low-volume STB provided a lower incidence of hemidiaphragmatic paralysis with no significant difference in analgesic efficacy relative to standard-volume STB for arthroscopic shoulder surgery.

Haemodynamic changes and incisional bleeding after scalp infiltration of dexmedetomidine with lidocaine in neurosurgical patients.

BACKGROUND: The purpose of this randomised controlled study is to compare the haemodynamic changes and the degree of incisional bleeding after scalp infiltration of lidocaine and dexmedetomidine versus lidocaine and epinephrine for patients with hemi-facial spasm undergoing microvascular decompression. METHODS: Fifty-two patients were injected with 5 mL of 1% lidocaine with either dexmedetomidine (2 µg/mL) or epinephrine (1:100,000 dilution) to reduce scalp bleeding. Mean blood pressure and heart rate were recorded every minute for 15 minutes after scalp infiltration. The primary outcome was the incidence of predefined hypotension, which was treated with administration of 4 mg ephedrine as often as needed. The number of administrations and total amount of ephedrine administered were also recorded as a measure of the severity of hypotension. The neurosurgeon scored incisional bleeding by numeric rating scale from 0 (worst) to 10 (best). RESULTS: The incidence of hypotension (68% vs. 34.8%, P = 0.02) and the frequency (P = 0.02) and total dose (P = 0.03) of ephedrine administered were lower in the dexmedetomidine group than in the epinephrine group. In addition, there was no difference in mean blood pressure between the two groups but heart rates were lower in the dexmedetomidine group (P = 0.01). Incisional site bleeding was better with epinephrine (median [interquartile range] of the numeric rating Score: 6 [4] in the dexmedetomidine group and 8 [2] in the epinephrine group; P < 0.001). CONCLUSION: The dexmedetomidine-lidocaine combination may be recommended as a substitute for epinephrine-lidocaine for scalp infiltration in neurosurgical patients, especially neurologically compromised patients.