Clinical Study Of Ultrasound-guided Continuous Femoral Nerve Block For Postoperative Analgesia After Total Knee Arthroplasty

ObjectiveIn recent years, the guided methods of nerve block have fundamentally innovatedwith the development of ultrasound technology. The study is to investigate the effect,adverse event and patient satisfaction of ultrasound-guided continuous femoral nerve block(CFNB) for postoperative pain relief after unilateral total knee arthroplasty (TKA).And tofurther explore the analgesic effect, dosage and patient satisfaction of the administrationmode of different PCA (patient-controlled analgesia, PCA).In order to find a appropriatedelivery model to provide a reference for clinical use.MethodsPart one: Fifty ASA (American Society of Anesthesiologists, ASA)Ⅰ~Ⅲpatientswere selected and the unilateral TKA were done with combined spinal-epidural anesthesia.After the surgery, the patients were scheduled to receive femoral nerve block catheterinsertion under the guidance by using a portable ultrasound systems with a linear6to13MHz transducer and continuous infusion of0.25%bupivacaine for analgesia. Pain wasassessed using a visual analogue scale of4,8,12,24,48,72hours ostoperatively at restand during continuous passive motion of the3day and the grading of muscle strength, theamount of local anesthetic, patient satisfaction and side effects were also recorded.Part two: Sixty ASA Ⅰ~Ⅲ patients for the unilateral TKA with combinedspinal-epidural anesthesia were randomly divided into three groups of different PCAdelivery mode after ultrasound guided femoral nerve cathetertion. Group A:15ml of aloading dose, background infusion2ml/h, each4ml of the PCA, lockout time30min,analgesia lasted for4d; Group B: loading dose of15ml, no background dose, each5ml of the PCA, lockout time30min, analgesia lasted for4d; Group C:15ml of a loading dose,background infusion2ml/h, the PCA of each4ml, lockout time30min, analgesia lastedfor2d followed the mode of no background dose,5ml of the each PCA, lockout time of30min, analgesia lasted for2d. The drugs were240ml of0.3%ropivacaine. The VAS atrest and during continuous passive motion of the three groups were recorded, strengthgrading, the incidence of adverse reactions, the amount of local anesthetic, the times ofPCA and patient satisfaction were also recorded.ResultsPart one: Patient rest VAS scores were lower than3at each time point. Comparedwith rest VAS of4h (0.9±0.4), The VAS of12h at rest (1.8±0.6) and the VAS of the3d during continuous passive motion (1.6±0.8) were higher (P <0.05). Three levels of limbquadriceps strength were achieved and does not affect the patients’ active functionaltraining. The dosage of Bupivacaine was219.9±8.8ml, the times of PCA was9.3±2.2,and6patients required additional analgesic drugs. The incidences of adverse events werelow (urinary retention5/50, nausea3/50) and patient analgesia satisfaction was high.Part two: No significant differences among the three groups were noted in thepostoperative VAS scores at rest and during continuous passive motion (P>0.05). Themuscle strength of the patients in three groups was good with no significant differences(P>0.05). No significant differences of the incidences of urinary retention and nauseaamong the three groups (P>0.05); No case was observed among the three groups aboutvomiting, hypoxia, itching, and cases of local anesthetic toxicity. The total volume ofropivacaine of4d in Group A was more than Group B and Group C (P <0.05), while therewas no significant difference between Group B and Group C. The times of PCA in GroupA were least, Group B were the most and Group C were between Group A and Group B. Inthe periods of0~24h and24~48h, the times of PCA in Group B were more than GroupA and Group C, while in the periods of48~72h and72~96h,the times of PCA in GroupA were less than Group B and Group C. The patients required additional analgesic drugsamong the three groups were no significant differences (P>0.05). The cases of the most satisfaction in Group B were less than Group A and Group C (P <0.05).ConclusionsPart one: After total knee arthroplasty, ultrasound-guided continuous femoral nerveblock with0.25%bupivacaine for postoperative analgesia can provide good pain relief,slight impact on muscle strength, low side effects and high patient analgesia satisfaction,so it is considered to be an ideal analgesia method for TKA surgery.Part two:(1) After TKA, ultrasound-guided continuous femoral nerve block forpostoperative analgesia with0.3%ropivacaine with different PCA delivery modes can allprovide good pain relief with slight impact on muscle strength and low side effects(2) The PCA delivery mode which is provided with the background dose during firsttwo days followed no background dose during the last two days, needs the least amount oflocal anesthetic, receives the high patient satisfaction, is suitable for clinical use.