ABSTRACT
Objective To study clinical data retrospectively and demonstrate the optimal injection site of adductor canal block by performing a cadaveric study.Methods Clinical part:clinical data from 19 patients,11 males and 8 females,aged 21 85 years,ASA physical status Ⅰ-Ⅲ,who received ultrasound guided adductor canal block were retrospectively collected.Among whom 9 received a mid-distance injection of 10 ml of 0.5％ ropivacaine and 10 received an injection of the same medication at the outlet of adductor canal.The primary endpoint was complete absence of cold sensation to ice cube on the medial side of calf at 30 minutes and 24 hours after injection.Cadaveric part:40 lower limbs,20 males and 20 females,were finally analyzed in the study.The distances from the anterior superior iliac spine (ASIS) to the medial tibial condyle,from ASIS to the entrance of the adductor canal,from ASIS to the exit of the canal (adductor tendinous opening),from ASIS to the site where sa phenous nerve emerges through the aponeurotic covering were measured respectively.The length of adductor canal,the relative location of adductor canal and the site where saphenous nerve pierces in the lower limbs were calculated.Results Clinical part:all 19 cases were successfully recorded with complete absence of cold sensation at 30 minutes after injection of local anesthetic and complete sensory recovery at 24 hours after injection.Cadaveric part:in all specimens,saphenous nerve enters adductor canal and coursed down until emerging at very close to the distal end of the canal with the saphenous branch of descending genicular artery.The length of the adductor canal was (10.0±2.1) cm.The entrance and the exit of adductor canal and the emerging site of the saphenous nerve located along the (54.7±3.0) ％,(76.0％±3.8) ％ and (74.1±3.2) ％ of sartorius muscle,respectively.Conclusion Performing ultrasound-guided adductor canal block at either the outlet of adductor canal or mid-distance of thigh can achieve comparable blockade of saphenous nerve.Cadaveric study implicated that the optimal injection site for adductor canal block should be the lower one-third of sartorius muscle.Ultrasound-guided injection of local anesthetics next to the descending genicular artery may possibly become a promising new method of saphenous nerve block.
ABSTRACT
BACKGROUND: The ultrasound-guided oblique subcostal transversus abdominis plane (OSTAP) block provides a wider area of sensory block to the anterior abdominal wall than the classical posterior approach. We compared the intra-operative analgesic efficacy of OSTAP block with conventional intravenous (IV) morphine during laparoscopic cholecystectomy. METHODS: Forty adult patients undergoing laparoscopic cholecystectomy under standard general anesthesia, were randomly assigned for either bilateral OSTAP block using 1.5 mg/kg ropivacaine on each side (n = 20) or IV morphine 0.1 mg/kg (n = 20). The intra-operative pulse rate, systolic and diastolic blood pressure and mean arterial blood pressure were monitored every five minutes. Repetitive boluses of IV fentanyl 0.5 microg/kg were given as rescue analgesia when any of the above-mentioned parameters rose more than 15% from the baseline values. Time to extubation was documented. Additional boluses of IV morphine 0.05 mg/kg were administered in the recovery room if the recorded visual analogue score (VAS) was more than 4. Nausea and vomiting score, as well as sedation score were recorded. RESULTS: The morphine group required more rescue fentanyl as compared to the OSTAP block group but the difference was not significant statistically. Time to extubation was significantly shorter in the OSTAP block group (mean [SD] 10.4 [2.60] vs 12.4 [2.54] min; P = 0.021). Both methods provided excellent analgesia and did not differ in postoperative morphine requirements. No between-group differences in sedation score and incidence of nausea and vomiting were demonstrated. CONCLUSIONS: Ultrasound-guided OSTAP block has an important role as part of balanced anesthesia. It is as efficacious as IV morphine in providing effective analgesia during laparoscopic cholecystectomy.