Arthroscopic medial meniscus trimming or repair under nerve blocks: Which nerves should be blocked?

BACKGROUND: This study aimed to determine the role of the sciatic and obturator nerve blocks (in addition to femoral block) in providing painless arthroscopic medial meniscus trimming/repair. MATERIALS AND METHODS: One hundred and twenty patients with medial meniscus tear, who had been scheduled to knee arthroscopy, were planned to be included in this controlled prospective double-blind study. The patients were randomly allocated into three equal groups; FSO, FS, and FO. The femoral, sciatic, and obturator nerves were blocked in FSO groups. The femoral and sciatic nerves were blocked in FS group, while the femoral and obturator nerves were blocked in FO group. Intraoperative pain and its causative surgical maneuver were recorded. RESULTS: All the patients (n = 7, 100%) in FO group had intraoperative pain. The research was terminated in this group but completed in FS and FSO groups (40 patients each). During valgus positioning of the knee for surgical management of the medial meniscus tear, the patients in FS group experienced pain more frequently than those in FSO group (P = 0.005). CONCLUSION: Adding a sciatic nerve block to the femoral nerve block is important for painless knee arthroscopy. Further adding of an obturator nerve block may be needed when a valgus knee position is required to manage the medial meniscus tear.

Ropivacaine in ultrasound-guided femoral nerve block: what is the minimal effective anaesthetic concentration (EC90)?

The objective of this study was to estimate the minimal effective anaesthetic concentrations of ropivacaine required to block the femoral nerve in 90% of patients. Forty-five patients who had knee surgery received ultrasound-guided femoral nerve block using 15 ml ropivacaine. The ropivacaine concentration given to a patient relied on the efficacy of the block in the previous patient, using the biased-coin design up-down sequential method. In the event of successful block, the next patient was randomly assigned to receive either the same ropivacaine concentration or a concentration 0.02% w/v less. In the event of a failed block, the next patient received a concentration 0.02% w/v higher. Successful block was defined as complete sensory and motor block before surgery together with pain-free surgery. The minimal effective ropivacaine concentration was estimated to be 0.167% w/v (95% CI 0.14-0.184%). Perineural injection of 15 ml ropivacaine 0.167% w/v under ultrasound guidance can provide successful femoral nerve block in 90% of patients.

Lidocaine use in ultrasound-guided femoral nerve block: what is the minimum effective anaesthetic concentration (MEAC90)?

BACKGROUND: This study aimed to estimate the minimum effective anaesthetic concentrations of lidocaine required to block the femoral nerve under ultrasound (US) guidance in 90% (MEAC90) of patients. METHODS: A minimum of 45 patients who had undergone knee arthroscopy were included in this observational study. All the patients received US-guided sciatic, obturator, and femoral nerve blocks. The femoral nerve block was performed using 15 ml of lidocaine. The lidocaine concentration given to a patient was determined by the response of the previous patient (a biased-coin design up-down sequential method). If a patient had a negative response, the lidocaine concentration was increased by 0.1% w/v in the next patient. If a patient had a positive response, the next patient was randomized to receive the same lidocaine concentration (with a probability of 0.89) or to receive a concentration 0.1% w/v less (with a probability of 0.11). A positive response was defined as complete sensory and motor block. The patients' responses were analysed to calculate the mean MEAC90. RESULTS: Fifty-two patients were required to complete the study; 45 had a positive response and seven had a negative response. The mean MEAC90 was estimated to be 0.93% w/v [95% confidence interval (CI), 0.8-1.03%]. Lidocaine 0.93% w/v was estimated to produce a successful block in 89% (95% CI, 78-100%) of patients. CONCLUSIONS: Perineural injection of 15 ml of lidocaine 0.93% w/v under US guidance could provide successful femoral nerve block in 90% of patients.

Lidocaine vs. magnesium: effect on analgesia after a laparoscopic cholecystectomy.

BACKGROUND: This double-blinded study aimed at evaluating and comparing the effects of magnesium and lidocaine on pain, analgesic requirements, bowel function, and quality of sleep in patients undergoing a laparoscopic cholecystectomy (LC). METHODS: Patients were randomized into three groups (n=40 each). Group M received magnesium sulfate 50 mg/kg intravenously (i.v.), followed by 25 mg/kg/h i.v., group L received lidocaine 2 mg/kg i.v., followed by 2 mg/kg/h i.v., and group P received saline i.v. Bolus doses were given over 15 min before induction of anesthesia, followed by an i.v. infusion through the end of surgery. Intraoperative fentanyl consumption and averaged end-tidal sevoflurane concentration were recorded. Abdominal and shoulder pain were evaluated up to 24 h using a visual analog scale (VAS). Morphine consumption was recorded at 2 and 24 h, together with quality of sleep and time of first flatus. RESULTS: Lidocaine or magnesium reduced anesthetic requirements (P<0.01), pain scores (P<0.05), and morphine consumption (P<0.001) relative to the control group. Lidocaine resulted in lower morphine consumption at 2 h [4.9 + or - 2.3 vs. 6.8 + or - 2.8 (P<0.05)] and lower abdominal VAS scores compared with magnesium (1.8 + or - 0.8 vs. 3.2 + or - 0.9, 2.2 + or - 1 vs. 3.6 + or - 1.6, and 2.1 + or - 1.4 vs. 3.3 + or - 1.9) at 2, 6, and 12 h, respectively (P<0.05). Lidocaine was associated with earlier return of bowel function and magnesium was associated with better sleep quality (P<0.05). CONCLUSION: I.v. lidocaine and magnesium improved post-operative analgesia and reduced intraoperative and post-operative opioid requirements in patients undergoing LC. The improvement of quality of recovery might facilitate rapid hospital discharge.

Addition of clonidine or dexmedetomidine to bupivacaine prolongs caudal analgesia in children.

BACKGROUND: Caudal block is a common technique for paediatric analgesia but with the disadvantage of short duration of action after single injection. Caudal dexmedetomidine and clonidine could offer significant analgesic benefits. We compared the analgesic effects and side-effects of dexmedetomidine and clonidine added to bupivacaine in paediatric patients undergoing lower abdominal surgeries. METHODS: Sixty patients (6 months to 6 yr) were evenly and randomly assigned into three groups in a double-blinded manner. After sevoflurane in oxygen anaesthesia, each patient received a single caudal dose of bupivacaine 0.25% (1 ml kg(-1)) combined with either dexmedetomidine 2 microg kg(-1) in normal saline 1 ml, clonidine 2 microg kg(-1) in normal saline 1 ml, or corresponding volume of normal saline according to group assignment. Haemodynamic variables, end-tidal sevoflurane, and emergence time were monitored. Postoperative analgesia, use of analgesics, and side-effects were assessed during the first 24 h. RESULTS: Addition of dexmedetomidine or clonidine to caudal bupivacaine significantly promoted analgesia time [median (95% confidence interval, CI): 16 (14-18) and 12 (3-21) h, respectively] than the use of bupivacaine alone [median (95% CI): 5 (4-6) h] with P<0.001. However, there was no statistically significant difference between dexmedetomidine and clonidine as regards the analgesia time (P=0.796). No significant difference was observed in incidence of haemodynamic changes or side-effects. CONCLUSIONS: Addition of dexmedetomidine or clonidine to caudal bupivacaine significantly promoted analgesia in children undergoing lower abdominal surgeries with no significant advantage of dexmedetomidine over clonidine and without an increase in incidence of side-effects.